Untitled - CNRS Guyane

Transcription

Table des matières
Eaux littorales, côtières et estuariennes, forçages environnementaux, Ressources
halieutiques
4
Remotely-sensed sea surface chlorophyll annual bloom characterization in the
Amazon River mouth basin, Milton Kampel [et al.] . . . . . . . . . . . . . . . . .
6
Caracterização Hidrológica e Sedimentológica do Estuário do Rio Cunãni, Amapá
– Brasil, João Paulo Da Silva [et al.] . . . . . . . . . . . . . . . . . . . . . . . . .
7
Hydro-sedimentary processes of a tropical estuary under Amazon influence., Sylvain Orseau [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
Enjeux et contraintes de l’évaluation de l’état écologique des eaux littorales guyanaises, Olivier
Monnier [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Geochemistry and isotope systematic in the groundwaters of French Guiana, Philippe
Negrel [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Liens entre dynamique du stock de crevettes et évolution de l’environnement côtier
en Guyane, Loïc Baulier [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
De la vasière à la mangrove : diversité, fonctionnement, dynamique des communautés et des écosystèmes
13
Responses of mangrove forests to climate change and variability., Mario Soares [et
al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
Fluctuations in the extent of mangroves of French Guiana driven by multi-decadal
changes in North Atlantic climate, Romain Walcker [et al.] . . . . . . . . . . . . .
16
Global patterns of aboveground carbon stock and sequestration on mangroves, Gustavo Estrada [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
Shell Beach Protected Area and Mangrove Forests, Suresh Kandaswamy [et al.] .
20
2
Impact of emersion/immersion cycles on the biogeochemical fluxes in an intertidal
mud bank of French Guiana, Swanne Gontharet [et al.] . . . . . . . . . . . . . . .
22
Bioturbation functional roles exhibited by the mangrove benthic communities in
French Guiana, Adélaïde Aschenbroich [et al.] . . . . . . . . . . . . . . . . . . . .
24
Mangrove Rehabilitation Weg naar Zee Using Sediment Trapping Technique, Sieuwnath Naipal [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
Sedimentary biogeochemical cycling in the Amazon- Guianas mobile mud belt: an
overview., Robert Aller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27
Changing times for mangroves as temperatures rise. Changing phenologies!, Norman Duke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28
Vulnérabilité des paysages littoraux et des eaux côtières, impact sur les ressources
associées
28
Environmental Sensitivity of Coastal Ecosystems from the Perspective of Oil Exploration: The Mouth of the Amazon, Valdenira Santos [et Al] . . . . . . . . . .
30
Transboundary risks associated with oil and gas industry in the Northern Brazilian
coast, Júlio Pellegrini [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
A pesca artesanal como vetor de desenvolvimento local en Oiapoque (Brasil)., Ricardo Pereira [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34
Suivi topographique de profils de plages des trois grandes anses de l’île de Cayenne
: implications sur les flux sédimentaires sableux des parties émergées et intertidales., Pierre Bourbon [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
La dynamique côtière de l’ouest guyanais, Johan Chevalier . . . . . . . . . . . . .
37
Savanes de Guyane : anthropologie des controverses sur le devenir de paysages
culturels, Marianne Palisse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
39
An Investigation of the Impact of Global Sea Level Rise Guyana’s Coastal Zone
and the Current Adaptive Capacity, Paulette Bynoe . . . . . . . . . . . . . . . .
41
Espèces emblématiques, indicatrices et à valeur halieutique. Réseaux trophiques
et contaminants
41
Scénario d’impact du changement climatique sur la pêche côtière et la biodiversité
halieutique, Fabian Blanchard [et al.] . . . . . . . . . . . . . . . . . . . . . . . . .
3
43
Is high biodiversity and complex trophic networks equal to ecosystem stability?:
A comparative study of tropical mangrove estuaries, Maria Ching Villanueva . .
45
Dynamique spatio-temporelle du peuplement de larves de poissons dans l’estuaire
du Mahury (Guyane)., Yann Rousseau . . . . . . . . . . . . . . . . . . . . . . . .
46
Environmental contaminants, oxidative stress and virus outbreaks in frigatebirds
from French Guyana, Manrico Sebastiano [et al.] . . . . . . . . . . . . . . . . . .
48
The influence of mesoscale features on the distribution and the diving behavior of
sea turtles nesting in French Guiana, Philippine Chambault [et al.] . . . . . . . .
50
Méthodes, outils, modèles. Sous-session Modèles économiques
50
Vulnerability versus resilience of small-scale fisheries in French Guiana, Luc Doyen 51
The impact of climate change on the French Guiana Shrimp Fishery, Bassirou Diop 53
The tragedy of ecosystems in open-access, Jean-Christophe Pereau . . . . . . . .
Méthodes, outils, modèles. Sous-session Télédétection
54
54
Bio-optical properties in waters of the lower Amazon River, Aline Valerio [et al.]
55
Utilisation des images satellite dans la définition de la stratégie du réseau de
surveillance DCE en Guyane, Luis Lampert [et al.] . . . . . . . . . . . . . . . . .
57
Aplicação de tecnologia LIDAR no monitoramento de áreas costeiras em diferentes
ambientes: costa amazônica e praias arenosas do Nordeste Brasileiro, Santos André
Luis Silva Dos [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
Détection et suivi des bancs de vase littoraux en Guyane française, Erwan Gensac [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
61
Structure-from-Motion photogrammetry for high-resolution coastal geomorphic
surveys, Guillaume Brunier [et al.] . . . . . . . . . . . . . . . . . . . . . . . . . .
63
Recent Pelagic Sargassum Blooms in Atlantic Equatorial Regions, James Franks .
64
Liste des auteurs
64
4
Eaux littorales, côtières et estuariennes,
forçages environnementaux, Ressources
halieutiques
5
Remotely-sensed sea surface chlorophyll
annual bloom characterization in the Amazon
River mouth basin
Milton Kampel ∗ 1 , Natalia Rudorff , Lucas Freitas , Aline Valerio , Fabio
Dall Cortivo , Maria Zoffoli , João Felipe Santos
1
Instituto Nacional de Pesquisas Espaciais (INPE) – Avenida dos Astronautas 1758 Sao Jose dos
Campos, Sao Paulo, Brasil 12227-010, Brésil
The Amazon River mouth basin (ARMB) is the largest of the Brazilian equatorial margin.
It is limited to northwest with the Demerara Plateau and to southeast with the Para-Maranhao
Basin. It covers an area of approximately 350,000 km2 including the continental shelf, slope and
deepwater region. The Amazon River plume influences coastal and oceanic processes from local to
global scales, particularly with regard to phytoplankton concentration and primary productivity,
bio-optical properties, nutrients input, carbon sink, coastal deposition and erosion. However, the
Amazon River plume is subject to energetic forcing from various environmental factors. This
study uses time series of remotely-sensed sea surface chlorophyll concentration (SSC) from 2002
to 2014 to investigate the phenology of phytoplankton bloom in the ARMB, Western Tropical
Atlantic. The seasonal phytoplankton cycle is the dominant mode of temporal variability. The
use of a Gaussian function to fit the temporal variability of SSC allowed the characterization of
the timing and magnitude of the annual phytoplankton bloom in the slope area. Modeled SSC
showed a few differences in relation to mean MODIS-derived temporal curves. SSC data showed
that the maximum surface bloom occurs in June, having initiated in April. This cycle is typical
of tropical waters of low latitudes where the bloom is initiated at lower vertical stability of the
water column allowing nutrients from deeper layers to fertilize waters of the mixed layer. It is also
known that phytoplankton blooms by the action of eddy upwelling and the dispersal of Amazon
River water. On the continental shelf, modeled SSC data showed a maximum peak around March
and a secondary peak in September-October. But it is also known that the coloration of these
waters is dominated by CDOM, not by chlorophyll pigments contained within living organisms.
Without extensive in situ data it would be difficult to conclusively prove which of the mechanisms
dominates the surface ocean color signal observed. It is expected that the results obtained in this
work are useful for the environmental management and monitoring required ensuring adequate
and Mots-Clés:
sustainable use
of natural
resources
in this
region.
ocean
color remote
sensing,
MODIS,
phytoplankton bloom, chlorophyll, a, Western
Tropical Atlantic, Amazon river mouth
∗
Intervenant
6
Caracterização Hidrológica e Sedimentológica
do Estuário do Rio Cunãni, Amapá – Brasil
João Paulo Da Silva
∗† 1
, Valdenira Santos 2 , Alberto Figueiredo Jr.
1
1
2
Universidade Federal Fluminense (Laboratório de Geologia Marinha - LageMar) – Brésil
Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá, Núcleo de Pesquisas Aquáticas
- IEPA/NuPAq (IEPA) – Rod. JK, km 10, 68902-280, Fazendinha, Macapá, Amapá, Brésil
Os estuários presentes na costa do Estado do Amapá, sofrem forte influência das descargas
hídrica e sedimentar do Rio Amazonas, propiciando um ambiente extremamente dinâmico e com
características únicas. O estuário do rio Cunãni é um dos poucos sistemas estuarinos, ao norte da
foz do Amazonas, na costa do amapá, que desagua diretamente no Oceano Atlântico. O presente
trabalho teve por objetivo, aplicar técnicas hidroacústicas e de mapeamento sedimentológico
para a caracterização hidrológica e sedimentológica do estuário do rio Cunãni. Os dados utilizados neste trabalho foram coletados no periodo de transição entre os regime chuvoso e seco da
região (agosto de 2014). Os dados de descarga líquida foram coletados com auxílio de um ADCP
(Acoustic Doppler Current Profiler) da empresa RDI instruments Teledyne com frequência de
600 KHz. As medições foram efetuadas em dois pontos, localizados entre o médio o baixo curso
do rio, ao longo de todo um ciclo semidiurno de maré (13 horas). Os dados foram processados e
analisados estatisticamente considerando a variação da vazão em função do tempo e a correlação
entre a variação da vazão e velocidade. A intrusão salina foi media utilizando um salinômetro
digital e um CTD RINKO Profiler. As amostras de sedimentos de fundo (143) foram coletadas
com uma draga do tipo van Veen, a cada quilômetro, na margem direita e canal do rio a fim de
verificar a variação nos depósitos da margem e fundo do canal. Para a análise de sedimento em
suspensão, 39 amostras de água superficial foram coletadas a cada 2 km. Os resultados indicam
que o estuário do rio Cunãni é dominado pela maré de enchente, classificando-o como um sistema
importador de sedimento. O prisma de maré alcança 28 Km a jusante, no entanto, a intrusão
salina não ultrapassa os 13 primeiros quilômetros do estuário com diminuição da salinidade (de 7
para 0,2). Os resultados das medidas de salinidade indicam que o estuário é parcialmente misturado tendendo a verticalmente homogêneo. A salinidade intersticial é conservada nos sedimentos
e acompanham o decaimento da salinidade das águas em direção a montante do rio, seguindo a
diminuição da granulometria dos sedimentos de fundo. Enquanto, que a concentração de sólidos
em suspensão, aumenta em direção a foz. Os dados analisados demonstram que existe uma contribuição do aporte hídrico e sedimentar, oriundos do Rio Amazonas, uma vez que ocorre uma
grande concentração de sedimentos de granulometria mais fina na foz e baixa concentração de
salinidade, embora exista a presença das águas oceânicas na desembocadura do rio Cunãni. Tais
características marcam a singularidade do ambiente estudado quando comparado com estuários
descritos
na literatura.
Mots-Clés:
Estuário, Frente Salina, Sedimentos
∗
†
Intervenant
Auteur correspondant: [email protected]
7
Hydro-sedimentary processes of a tropical
estuary under Amazon influence.
Sylvain Orseau
∗ 1
, Antoine Gardel† 2 , Nicolas Huybrechts‡
Lesourd§ 5
3,4
, Sandric
1
CNRS Guyane USR3456 (CNRS) – 2, av. Gustave Charlery 97300 - Cayenne, Guyane française
Laboratoire d’Océanologie et de Géosciences (LOG) – Université Lille I - Sciences et technologies,
CNRS : UMR8187, Université du Littoral Côte d’Opale – 28 av Foch 62930 Wimereux, France
3
Laboratoire Roberval - Unité de recherche en mécanique (LRURM) – utc – Centre de recherche de
Royallieu rue Personne de Roberval - BP 20250 60205 COMPIEGNE CEDEX, France
4
Centre d’études et d’expertise sur les risques, l’environnement, la mobilité et l’aménagement
(CEREMA - DTecEMF) – Ministère de l’égalité des territoires et du logement„ Ministère de l’Ecologie,
du Développement Durable et de l’Energie – 134 rue de Beauvais, CS 60039, 60280 Margny Lès
Compiègne, France
5
Morphodynamique Continentale et Côtière (M2C) – Université de Caen Basse-Normandie, CNRS :
UMR6143 – France
2
French Guiana shoreline is one of the most dynamic coasts in the world, due to the migration
of huge mud banks in shallow waters (5m to 20 m) built with silts originating from the sediment
plume of Amazon River (Brazil) [1]. Even if different studies have focused on mud bank features
[2, 3, 4, 5], impacts of their migration on sediment dynamic of estuaries has not been studied
yet.
For three years a mud bank has been migrating near the mouth of the Mahury estuary where
is located the sole harbor of French Guiana. This migration is inducing a severe siltation of the
navigation channel and providing a new source of fine-sediments for estuarine turbidity maximum system.
In order to characterize the flow pattern and the mud deposit processes more accurately, this
study aims to determine the contributions to sediment fluxes from residual currents and freshwater discharge through in situ measurements.
Multiple measurements of salt intrusion length and location of turbidity maximum allow to
analyze seasonal variation of salt and SPM distribution. Their also allow to establish relationship with freshwater discharge and tidal ranges. Measurements over a tidal and a neap-spring
cycles are performed to quantify how tidal currents and salinity stratification influence sediment
regimes. Then, it provide the basis for estimating sediment fluxes at each seasons and establish
a first insight of hydro-sedimentary processes during siltation phase.
In wet season ETM is confined to the estuary mouth and shifts toward the intermediate portion
∗
Intervenant
‡
§
†
8
of salt length intrusion during dry season. SPM dynamics are mainly due to the resuspension
of soft mud occurring during spring tides. SPM concentrations are higher during flood tide suggesting the sedimentation of mud at the location of the turbidity maximum. In some cases, when
strength of current is significant during ebb tide and high water slack period is short, strongest
resuspension can be noticed.
In dry season, density-stratification occurring in the early flood tides induces the trapping of
sediments in bottom layer. This process can lead to favor mud inflows into the estuary. The
decomposition of residual sediment fluxes underlines a strong landward sediment flux dominated
by advection at spring-tides and for both seasons.
Over several years, natural filling of the Mahury estuary will be enlarge during the migration of
mud bank through the estuary mouth. However, some factors like extreme freshwater discharge
could play a key role on flushing of slightly consolidated deposits. To complete these first interpretations, measurements should be conducted during an inter-bank phase to compare residual
sediment fluxes and quantify the impact of mud bank migration on sedimentation. Future works
also include the built of a numerical model to study long-term morphological changes of the
estuary mouth and surrounding areas.
References
Allison, MA, Lee, MT, Ogston, AS & Aller, RC. Origin of Amazon mudbanks along the northeastern coast of South America. (2000).
Augustinus, P. The influence of the trade winds on the coastal development of the Guianas at
various scale levels: a synthesis. Marine Geology 208, 145151 (2004).
Gardel, A. & Gratiot, N. A Satellite Image–Based Method for Estimating Rates of Mud Bank
Migration, French Guiana, South America. Journal of Coastal Research (2005).
Gratiot, N., Gardel, A. & Anthony, E. Trade-wind waves and mud dynamics on the French
Guiana coast, South America: Input from ERA-40 wave data and field investigations. Marine
Geology 236, 1526 (2007).
Winterwerp, JC, de Graaff, RF, Groeneweg, J & Luijendijk, AP. Modelling of wave damping at
Guyana
mud coast.
Coastal
Engineering
249261 residual
(2007). sediment fluxes, density stratification
Mots-Clés:
Tropical
estuary,
mud bank54,
migration,
9
Enjeux et contraintes de l’évaluation de l’état
écologique des eaux littorales guyanaises
Olivier Monnier
1
∗ 1
, Franck Chow-Toun , Stéphanie Rey
Onema (Direction de l’action scientifique et technique (DAST)) – Office National de l’Eau et des
Milieux Aquatiques (ONEMA) – 5 square Félix Nadar - 94300 Vincennes, France
La directive cadre sur l’eau a pour objectif la non dégradation ou la restauration de l’état des
eaux. En termes de planification, la démarche consiste tout d’abord à délimiter des masses d’eau
sur la base de critères morpho-sédimentaires et hydrologiques. Ainsi, en ce qui concerne les eaux
littorales guyanaises, neuf masses d’eau de transition (estuaires) et une masse d’eau côtière ont
été définies. L’étape suivante consiste à évaluer le risque de dégradation des masses d’eau sur
la base de la connaissance des pressions anthropiques et de leurs incidences. Afin de confirmer
ou d’infirmer les conclusions de cette analyse de risque, mais également pour évaluer sur le long
terme l’état général des masses d’eau, un suivi dans le milieu de certaines substances chimiques
et d’éléments de qualité hydromorphologiques, physico-chimiques et biologiques est à mettre en
place. Les données ainsi acquises doivent permettre cette évaluation directe de l’état des eaux et
des milieux. La DCE a donc besoin d’indicateurs d’état capables de rendre compte de l’impact
des différentes pressions. De tels indicateurs sont donc préférentiellement intégrateurs de la
variabilité naturelle spatiale, de la variabilité naturelle temporelle et de l’impact des différentes
pressions anthropiques.
Dans les eaux de transition des grands estuaires de Guyane, comme dans les eaux marines
proches de la côte, la construction d’outils d’évaluation de l’état écologique constitue une attente
importante pour la gestion, du fait de la concentration des activités et des pressions anthropiques
dans la bande côtière du territoire. Par ailleurs, le littoral guyanais est soumis à une forte
variabilité des conditions naturelles du fait de l’apport de sédiments et d’eau douce en provenance
de l’Amazone. Les mécanismes complexes de transport et de dépôt des vases amazoniennes
induisent une grande variabilité hydro-sédimentaire et hydro-chimique, d’incessants déplacements
des zones d’interface entre terre et mer et une concurrence dans ces zones entre vasières et
mangroves. Face à ces puissants facteurs de variabilité des biocénoses et de gommage des effets
des pressions anthropiques, l’enjeu en termes de recherche est alors de bien appréhender cette
variabilité naturelle afin de s’en affranchir le plus possible, ce qui peut conduire à la prospection
de solutions de développement d’indicateurs alternatives à ce qui se fait traditionnellement dans
le cadre de la DCE. De même, il convient de bien mesurer les enjeux de gestion afin de ne pas
s’investir dans le développement d’outils qui ne répondraient pas à l’objectif premier de la DCE.
Cette présentation a donc pour objectifs de dresser le bilan des expertises sur la pertinence des
éléments de qualité (groupe de travail DCE Guyane), en particulier biologiques, et des études de
développement d’indicateurs de l’état écologique, ainsi que les perspectives de recherche qui en
découlent.
Mots-Clés: Guyane, eaux littorales, DCE, état écologique, bioindication
∗
Intervenant
10
Geochemistry and isotope systematic in the
groundwaters of French Guiana
Philippe Negrel
1
∗ 1
, Emmanuelle Petelet-Giraud
2
Bureau de recherches géologiques et minières (BRGM) – Bureau de Recherches Géologiques et
Minières (BRGM) – 3 Avenue Claude Guillemin, B.P. 36009, 45060 Orléans, France
2
BRGM – Ministère de l’Enseignement Supérieur et de la Recherche Scientifique – France
The long use by the population of French Guiana of untreated river water for drinking
purposes has led to important impacts on public health in the recent periods. Consequently,
groundwater was of major importance as a possible alternative drinking water supply to reduce
these impacts. As part of a major research program to characterize the groundwater resources
in French Guiana over the last decades, several studies have been carried out aimed at constructing a geochemical reference for groundwater quality and water-rock interaction signatures.
Basically, we have characterized atmospheric inputs and chemical and isotopic compositions in
river catchments and in groundwaters throughout French Guiana. Recent research focused on
the geochemistry of ground waters for which the database serve to build up a referential for
this region and were valorized in conjunction with geologic, hydrodynamic, etc., data, as one
main objective is to better define the functioning of French Guiana groundwater resources and
aquifers.
A specific focus was realized on the coastal area where groundwater samples have been collected
from shallow drill holes along the coast, which is the only densely populated area in French
Guiana, and deeper wells in the basement around Cayenne from which groundwater is pumped
from bedrock fractures. Surface water samples were collected from two coastal streams and from
one small inland river, and one seawater sample was collected from near Cayenne.
Major cations show excess due to water-rock interaction; stable isotopes of the water molecule
reveal that most groundwaters fit with both local and global meteoric water lines without evaporation impacts. The strontium isotope ratios indicate the existence of at least three end-members
that corresponds respectively to the drainage of metavolcanic rocks, meta-sedimentary lithology
and plutonic granitoid intrusions. The strontium isotope and cation ratios yield evidence of
increase in the weathering of metavolcanic rocks with the larger divergence between surficial and
deep weathering of about 60%.
We report also Rare Earth elements (REE) contents as well as the isotopic composition of Nd in
groundwaters and surface waters. The contents of individual dissolved REEs and total dissolved
REEs in the investigated waters, vary over several order of magnitude and fall within the range
observed by several authors either in surface or groundwaters. The values appear broadly independent of other parameters such as total dissolved solids and pH but organic matter seems play
a significant role in controlling the dissolved REE contents in waters. REE crustal normalized
patterns exhibited relatively uniform patterns with enrichment in heavy REEs. The neodymium
∗
Intervenant
11
isotope in some ground waters reveals a possible influence of sedimentary deposits in the coastal
area that originate from the Amazon and on the other hand, some groundwaters plot in agreement with the field of parent rocks, suggesting that Nd originates from the weathering of the
bedrock.
Finally, we report on the geochemistry of boron in coastal groundwaters. Large variations in
both the boron content (factor > 10) and boron isotope signature (up to 43%) are recorded.
The different correlations observed between the groundwater geochemistry, the pH and the boron
isotope signatures are related mainly to the dissolution of the silicate host rocks. The French
Guiana coastal aquifers represent the first case history where a 10B enrichment with increasing
pH is evidenced.
This geochemical and multi-isotopic approaches to the groundwater in French Guiana have allowed the origin and complex relationships between the different compartments of the hard-rock
aquifers
to be more
clearly defined.
Mots-Clés:
groundwater,
geochemistry, isotopes
12
Liens entre dynamique du stock de crevettes et
évolution de l’environnement côtier en Guyane
Loïc Baulier
1
∗† 1
, Amira Magraoui , Fabian Blanchard‡
1
Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer) – Guyane française
Le stock de crevettes Farfantepenaeus subtilis de Guyane, autrefois objet de la première
pêcherie locale, a connu ces dernières années un déclin important. Deux chutes de recrutement
se sont succédé en 1999 et 2007, pour conduire à des niveaux de stock historiquement bas.
L’absence de relation stock-recrutement claire ainsi que l’antériorité des baisses de recrutement
sur les baisses de stock adulte conduisent à ne pas considérer la pêche comme la cause première
de la situation actuelle.
Les origines du déficit de recrutement de F. subtilis ont donc été recherchées dans les conditions environnementales. Le milieu littoral guyanais est sous l’influence de nombreuses variables
forçantes, dont certaines sont affectées par le changement climatique, et affiche une dynamique
rapide. Différentes séries de variables, issues de mesures in-situ, de la télédétection ou de sorties
de modèles ont été testées. Parmi ces variables, la concentration de chlorophylle a (reflétant la
production primaire) et les courants marins se sont avérés significativement corrélés au recrutement des crevettes, mais n’expliquent qu’une faible part de sa variabilité au niveau mensuel.
Ces premières conclusions appellent à poursuivre les études en affinant les recherches sur les relations entre les variables ainsi identifiées et le recrutement de F. subtilis, afin de mieux comprendre
le déterminisme
de ce dernier.
Mots-Clés: crevette
brune, recrutement, variabilité environnementale
De la vasière à la mangrove : diversité,
fonctionnement, dynamique des
communautés et des écosystèmes
∗
Intervenant
‡
†
13
Responses of mangrove forests to climate
change and variability.
Mario Soares ∗† 1 , Gustavo Estrada 1 , Viviane Fernandez 1 , Marciel
Estevam 1 , Paula Almeida 1 , Filipe Chaves 1
1
Universidade do Estado do Rio de Janeiro (UERJ) – UERJ, Av. Sao Francisco Xavier, 524,
Maracana, 20550-900, Rio de Janeiro, Brésil
Among the impacts of climate change on mangroves, we can highlight mean sea level rise
(MSLR), the increase in the atmospheric CO2 concentration and changes in temperature, in rainfall patterns, in the incidence of extreme events and in the ocean circulation patterns. Among
these effects, MSLR is considered the one with the greatest potential of impact on mangroves.
The behavior of mangroves in response to MSLR will depend on the balance between sea level
rise and its compensation through sediment deposition and sub-surface processes, as well as on
the existence of areas for a possible retraction of mangroves. This retraction process will also
depend on the competition with non-halophytes communities in the coastal plain and on the
compatibility of the rate of MSLR with the life cycle of mangrove species. As a result, we can
identify three possible behaviors of mangrove forests: erosion, retraction and resistance, which
shall determine three modes of mangrove occurrence: (a) maintenance; (b) exclusion;(c) occurrence in refugees.
In Rio de Janeiro (Brazil), the mangroves of Guaratiba are the target of a long-term monitoring program since 1996, allowing the construction of an unique data series. The results
obtained by this program allowed the identification of a migration process of mangrove forests
toward the adjacent salt flats (hypersaline plains), corroborating conceptual models, according to
which mangroves could migrate toward the continent in response to sea level rise. Over the past
18 years, a migration of ca. 111 meters of the mangrove forests toward the salt flats was detected.
The integrated analysis of the colonization process of salt flats by mangrove species and of
the structural properties of forests established before 1996 allows the identification of a process
of ecological succession. In this process, fringe forests would be at the maturity stage, basin
forests at an advanced stage of early development and transition forests (at the interface with
salt flat) would be at a maturing sequence from initial stages of colonization, going through different stages of colonization, up to initial stages of early development, when natural thinning occurs.
The analysis of the time series of climate data leaded to the calculation of the regional sequential water balance and to a detailed analysis of the influence of water availability in the
soil on the migration process of mangrove forests toward salt flats. It was observed that the
migration of mangrove forests is strongly controlled by water availability in the soil. In wet
periods, with greater accumulation of water in the soil and consequent reduction in water and
∗
†
Intervenant
14
salt stress at the interface with salt flat, higher growth rates of pre-established saplings and the
advance of the colonization process are observed. This pattern is also detected in the analysis
of the time series of satellite images from 1985 and 2006, which reveals that mangrove forests
expand over the salt flats in wet periods. On the other hand, during dry periods,the behavior
of mangrove forests depends on terrestrial freshwater input. In sites with terrestrial input,the
rate of mangrove forests expansion decreases, while in sites without terrestrial input, mangrove
forests retreat and salt flats expand.
The results of the long-term studies in the mangroves of Guaratiba leaded to the identification of
the response of mangrove forests to MSLR as well as to the effect of rainfall and water availability
oscillation on this ecosystem. It was also possible to confirm that the migration of mangrove
forests through the colonization of salt flats by mangrove species is controlled by both sea level
rise Mots-Clés:
and climate Sea
variability.
Level Rise, Water Balance, Colonization, Migration, Salt Flats
15
Fluctuations in the extent of mangroves of
French Guiana driven by multi-decadal
changes in North Atlantic climate
Romain Walcker ∗ 1 , Edward Anthony 2 , Christophe Cassou 3 , Robert Aller
4
, Antoine Gardel 5 , Christophe Proisy 6 , Jean-Michel Martinez 7 , François
Fromard 1
1
Laboratoire Ecologie Fonctionnelle et Environnement (EcoLab) – CNRS : UMR5245, Observatoire
Midi-Pyrénées, PRES Université de Toulouse, Université Paul Sabatier (UPS) - Toulouse III, Institut
National Polytechnique de Toulouse - INPT – 118 Route de Narbonne 31062 Toulouse, France
2
CEREGE – Université Aix-Marseille-CNRS-IRD – Aix en Provence, France
3
Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS) –
CERFACS – France
4
School of Marine and Atmopheric Sciences (SoMAS) – Stony Brook University Stony Brook, NY
11794-5000, États-Unis
5
CNRS : UMR8187, Université du Littoral Côte d’Opale – 28 av Foch 62930 Wimereux, France
6
BotAnique et BioinforMatique de l’Architecture des Plantes (AMAP) – Institut national de la
recherche agronomique (INRA) : UR0931, Institut de recherche pour le développement [IRD], CNRS :
UMR5120, Centre de coopération internationale en recherche agronomique pour le développement
[CIRAD] : UMR51, Université Montpellier II - Sciences et techniques – Bd de la Lironde TA A-51/ PS
2 34398 Montpellier cedex 5, France
7
Laboratoire Géosciences Environnement Toulouse (GET-IRD) – Observatoire Midi-Pyrénées –
Observatoire Midi Pyrénée 14, avenue Édouard Belin 31400 TOULOUSE, France
The ocean surface is crossed by fields of waves generated by ocean surface winds. These waves
travel over basin-wide distances and drive coastal sediment transport when they reach continental margins. In a warming world and over multi-decadal timescales, ocean wave climates may
undergo significant changes, thus leading to potentially serious impacts on the morphology of exposed tidal wetlands. These changes should be observable on the most extensive open-coast tidal
wetlands, and especially on the highly dynamic and pristine mangrove coast of French Guiana.
The goal of our study was to test the hypothesis that ocean wave multi-decadal variability drives
changes in the morphology of French Guiana mangroves. To achieve this objective, we analysed
changes in North Atlantic wave parameters and we quantified changes in the extent of French
Guiana mangroves from 1950 to 2014. We retrieved significant wave-heights (HS), mean wave
periods (TM) and mean wave directions (
thetaM) from the European Centre for Medium-Range Weather Forecasts reanalysis products
and we produced time series of mangrove maps using archival remote sensing images. We used
complex empirical orthogonal function (CEOF) decomposition to extract the main mode of
mangrove surface area (MS) variability and singular value decomposition (SVD) to test the relationships between MS and HS, TM and
thetaM. Our results revealed a multi-decadal fluctuation in MS that is on the order of 15 000 ha
∗
Intervenant
16
over the 1950-2014 period. The SVD results indicated that this fluctuation cross-covaried with
HS, TM and
thetaM over the North Atlantic sector, particularly in the region immediately off the French
Guiana coast that is remotely forced by the North Atlantic Oscillation (NAO) during the winter
season. Our results provide evidence based on linear statistics that variations in the extent of
mangroves are driven by large-scale, low-frequency changes in North Atlantic waves that are
related to an internal mode of climate variability (the NAO), i.e. independent from external
climate drivers such as green-house gases and aerosols (anthropogenic factors) and solar/lunar
variability and volcanoes (natural factors). The mangrove-climate relationship is hypothesized to
operate through wave pounding, which alters the mud substrates on which mangroves thrive and
which varies with the phase of the NAO. The North Atlantic waves are strongly coupled to the
NAO, which lead to strengthening (weakening) of their intensity during positive-NAO (negativeNAO) phases. Increased (decreased) wave heights favour mangrove shoreline landward (seaward)
retreat (expansion). Our study is one of the most comprehensive assessments of changes in the
extent of mangroves over multi-decadal timescales in relation to large-scale atmospheric drivers.
With regards to the functioning of the Amazon-influenced coast, we suggest that alternations of
periods of lower and higher wave energy driven by the NAO are also responsible for the creation
of bank and interbank phases which are at the origin of the mud bank system in the region of
Cabo
Cassipore,Amazon,
Brazil. climate, coastal changes, French Guiana, mangroves, North Atlantic OscillaMots-Clés:
tion, ocean waves, trade winds.
17
Global patterns of aboveground carbon stock
and sequestration on mangroves
Gustavo Estrada
∗† 1
, Mário Soares
2
1
2
Universidade do Estado do Rio de Janeiro (UERJ) – UERJ, R. Sao Francisco Xavier, 524, 4023-E,
Universidade do Estado do Rio de Janeiro (UERJ) – UERJ, R. Sao Francisco Xavier, 524, Maracana,
4023E, 20550-900, Rio de Janeiro, Brésil
In order to contribute to understanding the role of mangroves as carbon (C) stores, the existence of global patterns of variation of C stock and sequestration in the aboveground biomass
(AGB) of mangroves was tested. Data on C stock and sequestration in the AGB of mangroves
from 73 published articles were averaged and tested for the dependence on latitude, climatic
factors (WorldClim), physiographic types (either putative or explicitly classified) and age, using
regression analysis and ANOVA.
Global means of C stock (78.0 ± 64.5 tC.ha-1; max = 418.5 tC.ha-1; min = 0.9 tC.ha-1) and sequestration (2.9 ± 2.2 tC.ha-1.yr-1; max = 9.7 tC.ha-1.yr-1; min = 0.4 tC.ha-1.yr-1) showed that
mangroves are among the forest ecosystems with greater capacity of C storage in AGB. At the
global scale, C stock increases toward the equator (R2 = 0.22; p < 0.01), having distinct means
per latitudinal range (0-10◦ = 103.72 ± 78.97 tC.ha-1; 10-25◦ = 75.47 ± 55.05 tC.ha-1; > 25◦
= 43.39 ± 44.91 tC.ha-1; F = 10.69, p < 0.05). These results reinforces, with additional and
updated data, what other meta-analysis have previously shown before and indicates the influence
of solar radiation and climate (at both global and regional scales) on the AGB of mangroves.
In effect, our results confirm that C stock in AGB is dependent on 13 climatic parameters, but
primarily annual precipitation (R2 = 0.28; p < 0.01), water balance (R2 = 0.23; p < 0.01),
temperature annual range (R2 = 0.23; p < 0.01), minimum temperature of the coldest month
(R2 = 0.21; p < 0.01) and mean temperature of the coldest quarter (R2 = 0.20; p < 0.01).
These results indicate, therefore, that global and regional factors explain 20 to 30% of C stock
variability. Due to the lower number of studies presenting estimates of C sequestration in AGB
(n = 26) and the high variance of the existing data, no significant latitudinal or climatic pattern
was found, although a tendency of increased C sequestration toward the equator is apparent in
the graphical analysis.
In effect, local factors were shown to explain the other 70-80% of the variability not explained by
global/regional factors. When height was integrated as part of the independent variable of the
regression analysis between C stock and latitude (using the latitude/height ratio), the percentage
of explanation increased from 22% to 45% (R2 = 0.45; p < 0.01), indicating the contribution
of local factors. Furthermore, it was shown that C stock and sequestration vary according to
physiographic types (fringe > basin > shrub mangroves), despite of the fact that data came
from different biogeographical regions (both Atlantic-East Pacific - AEP - and Indo-West Pacific
∗
†
Intervenant
18
- IWP), latitudinal ranges, climatic regions and geomorphological settings, indicating the importance of hydroperiod and edaphic factors to the local variability of C stock. However, this pattern
was again only significant for C stock (F = 132.5; p < 0.01). Still at the local scale, C stock
increases (R2 = 0.70; p < 0.01) and C sequestration decreases (p = 0.16) with age, although
this decrease is preceded by an initial phase of increase (ending in the transition of colonization
and early development stages) not captured in the analysis. The age of the forests thus explains
70% of C stock variability, demonstrating the importance of disturbances and forest dynamics
to the local variability of C stock.
Based on recent estimates of global mangrove area and on the global averages presented in
this study, global C stock and sequestration in the AGB of mangroves is estimated at 1.23 ±
0.93 PgC and 0.04 PgC.yr-1, respectively. The concentration of mangrove area (53%) in the
0-10◦ region, where the global average of C stock is the higher one, leads to an even higher concentration of C stock in this region (62%), highlighting the relevance of the equatorial mangroves
as C sinks and thus for global warming mitigation. Adding the best available global averages
of C stock and sequestration in the below ground biomass and in the soil of mangroves to this
estimate, a global C stock of 9.58 PgC (or ca. 6 years of anthropogenic emissions of greenhouse
gases - GHG) and a global C sequestration of 0.142 PgC.yr-1 (or ca. 10% of the annual emissions
of anthropogenic GHG) are reached.
In conclusion, this study has shown that 20-30% of C stock variability in the AGB of mangroves
is explained by global and regional factors while local factors contribute with the other 70-80%
part of the explanation. An increase of the number of studies in the AEP region (3/4 are concentrated in the IWP region) and an improvement of the studies on C sequestration in the AGB
(eg. longer monitoring periods) are two of the main constraints for reducing the uncertainties of
the Mots-Clés:
estimates presented
here.
Global Warming,
Mitigation, Climatic Factors, Physiographic Types
19
Shell Beach Protected Area and Mangrove
Forests
Suresh Kandaswamy∗ 1 , Tana Yussuff
1
†‡ 1
Protected Areas Commission, Guyana (Protected Areas Commission, Guyana) – Georgetown, Guyana
The Protected Areas Commission was established in 2012 under the Protected Areas Act 2011
as an agency of the government. It currently falls under the Department of Natural Resources
and the Environment within the Ministry of Presidency. It is charged with the establishment,
management, maintenance, and promotion of national protected areas in Guyana. The Protected
Areas Commission manages hinterland protected areas in the country and the urban parks in
Georgetown. The hinterland protected areas represent diverse and unique ecosystems. They
include the Shell Beach Protected Area in Region 1 in the northwest part of Guyana, Kaieteur
National Park in Region 8, and Kanuku Mountains Protected Area in Region 9 in the south of
Guyana. The urban parks include the Guyana Zoo, Botanical Garden, and the National Park.
Shell Beach Protected Area (SBPA), established in 2011, is a relatively new protected area. At
SBPA, both the terrestrial and marine environment is important. One of the overarching goals
of SBPA is to protect and conserve biodiversity, including the largest contiguous remaining mangrove and coastal swamp forest and sea turtle nesting beaches in Guyana.
As the name implies, SBPA is important for its beaches that serve as nesting grounds for four
threatened species of sea turtles. It is also important because it is home to the largest intact
contiguous mangrove forest cover in Guyana. 13 percent, or 15,000 ha, of Shell Beach Protected
Area is comprised of mangrove forests, both coastal and riverine, and play an important role in
protection of the shoreline and the associated biodiversity. Mangrove forests occur in a narrow
belt of a few kilometers wide along the Altlantic coast, the lower reaches and mouth of the Waini
River and in a small portion along the Moruca River. Given that the mangrove forests along
the coast east of the Pomeroon River to the border with Suriname has been cut, this stretch of
mangrove is important for Guyana.
The conservation and protection of mangroves at SBPA supports many important national and
international goals. It supports the low-carbon development strategy, the national biodiversity
strategy and action plan, the UN sustainable development goals, and Guyana’s obligations towards the UN Convention on Biological Diversity. The National Mangrove Management Action
Plan also attests to the importance of mangrove protection in Guyana. Protection for mangroves
is accorded through various act such as the Guyana Forestry Act, the Sea Defense Act, and the
Protected Areas Act.
The coastline along the SBPA is dynamic. Shell accretion and erosion is a cyclic process creating
beaches that support nesting sea turtles. The accretion isolates mangrove forests from the ocean.
∗
Intervenant
‡
†
20
When beaches erode, mangrove forests provide the necessary sea defense that help prevent sea
water intrusion into swamps and wetlands further inland and Amerindian community farm lands
from becoming unproductive.
Protected Areas in Guyana, including Shell Beach Protected Area, are considered to be a managed resource protected area, where Amerindian communities can continue to use resources
sustainably for traditional subsistence purposes. There are 11 stakeholder Amerindian communities that live adjacent to the SBPA, and the coast and mangrove forests support various
socio-economic activities for some of these communities. Many depend on it for traditional
subsistence activities such as fishing, catching crabs, and building houses. Bee keeping within
mangrove forests is also suggested by communities to help support alternate livelihoods.
However, there is very little information on the health of the mangrove forests in the SBPA,
which is one of the research priorities in the SBPA management plan completed in 2014. Further research also needs to be done on the impact of erosion on mangrove forests and fresh
water swamps and wetlands further inland. Research is also needed on the use of mangroves by
communities
andMangroves,
their impacts
or conservation
benefits.
Mots-Clés:
Guyana,
Protected areas
21
Impact of emersion/immersion cycles on the
biogeochemical fluxes in an intertidal mud
bank of French Guiana
Swanne Gontharet ∗† 1 , Lionel Denis 1 , Olivier Mathieu 2 , Fernando Gomez
, Luis Felipe Artigas 1 , Sandric Lesourd 4 , Jacinthe Caillaud 1 , Gwendoline
Duong 1 , Jean Lévêque 2 , Marie-Jeanne Milloux 2 , Max Sarrazin 5 , Maxime
Gommeaux 6
3
1
4
6
CNRS : UMR8187, Université du Littoral Côte d’Opale – France
2
Laboratoire Biogéosciences – Université de Bourgogne, CNRS : UMR6282 – France
3
Laboratory of Plankton Systems, Oceanographic Institute, University of São Paulo – Brésil
Morphodynamique Continentale et Côtière (M2C) – Université de Caen Basse-Normandie, CNRS :
UMR6143 – France
5
Laboratoire des Moyens Analytiques (LAMA) – Guyane française
Groupe d’Etude sur les Géomatériaux et les Environnements Naturels et Anthropisé (GEGENA) –
Université de Reims - Champagne Ardenne – France
The French Guiana coast is characterized by the occurrence of unstable mud banks, resulting
in important shore instability with large consequences in its ecology, development and management. These mud banks, originating from the huge Amazon suspended sediment discharge,
migrate northwestward through successive depositional and erosional cycles. These cycles are
controlled by a complex interaction of hydrodynamical (wave action, tidal forcing, wind-forced
currents) and sedimentary (amounts of inorganic and organic materials exchanged between the
coast and the Atlantic Ocean) parameters. These structures might be temporally emerged depending on tidal cycles and their topographic elevation. This temporal emersion permits biological colonization and stabilization by the development of microphytobenthos (MPB) on surface
sediments and of opportunistic mangroves (i.e. Avicennia germinans). Thus, they receive organic matter (OM) from various sources: marine suspended particulate matter (SPM), coastal
mangrove plants and in situ development of MPB mats.
In this frame, the BIOBANK project (PIG CNRS, 2014) aimed to determine, at different airexposure durations, (i) the characteristics of the sedimentary environment and its influence on
the sedimentary OM degradation and release of nutrients for primary producers, (ii) the relative contribution of different OM sources to sediments and the intensity of inorganic compound
fluxes at the water-sediment interface, with emphasis on the role of MPB biofilms, and, (iii) the
variability of the MPB biological and functional diversity. A field campaign was conducted in
July 2014 on the intertidal mud bank near the East of pointe Isere. Three stations were selected according to their distinct topographic elevation and thus to their air-exposure duration,
resulting in diverse degrees of mud compaction and biological colonization. Surface sediments,
sedimentary cores and MPB were sampled, at each station, at the beginning and the end of
∗
†
Intervenant
22
emersion.
Preliminary results indicate that sediments, having homogenous textural and mineralogical compositions, showed an increase in their cohesion with the duration of the emersion period. Isotopic
measurements (13C and 15N values) show that the sedimentary OM was mainly derived from
SPM associated with variable amounts of OM originating from MPB and mangrove plants.
Sediment-water exchanges, as measured by whole core incubation technique, allowed quantifying
a slow uptake of oxygen during immersion (100-350 µmolO2.m-2.h-1), indicating rather limited
mineralization processes. On the contrary, during the emersion period, the MPB production
could reach more than 3000 µmolO2.m-2.h-1 and the relative amounts of chlorophyll a (chl a)
over total pigments were higher than 50 %, showing a good physiological condition of micro-algae.
The relative contribution of MPB to total sedimentary OM was higher during emersion, which
is consistent with the observed increase of the chl a concentrations at the sediment surface. Microscopic observations indicated that, despite a low MPB diversity, the community assemblages
varied significantly depending on the emersion duration.
These results allow a better understanding of the biogeochemical and ecological functioning of
mud banks, and their role for associated pelagic and benthic ecosystems. Further investigations will focus on the relationships between sediment characteristics, OM quality and microbial
diversity
and functionality.
Mots-Clés:
Organic matter, Biogeochemical cycles (C, N), Mud compaction, Microphytobenthos
(MPB), Intertidal mud banks
23
Bioturbation functional roles exhibited by the
mangrove benthic communities in French
Guiana
Adélaïde Aschenbroich ∗ 1 , Emma Michaud 1 , François Fromard 2 , Antoine
Gardel 3,4 , Franck Gilbert 2 , Thomas Stieglitz 5 , Robert Aller 6 , Marcos
Tavares 7 , Arthur Alt 1 , Isabelle Bihannic 1 , Vincent Le Garrec 8 , Gérard
Thouzeau 1
1
Laboratoire des Sciences de l’Environnement Marin UMR 6539 (LEMAR) – Institut Universitaire
Européen de la Mer (IUEM) – Technopôle Brest Iroise, Rue Dumont d’Urville, 29280 Plouzané, France
2
Laboratoire Ecologie Fonctionnelle et Environnement UMR 5245 (EcoLab) – Université Paul Sabatier
(UPS) - Toulouse III – 118 Route de Narbonne 31062 Toulouse, France
3
Laboratoire d’Océanologie et de Géosciences (LOG) – Université du Littoral Côte d’Opale, CNRS :
UMR8187 – 28 av Foch 62930 Wimereux, France
4
CNRS – CNRS : USR3456 – Immeuble Le Relais 2, avenue Gustave Charlery 97300 Cayenne, France
5
Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) – James Cook University,
Townsville Qld 4811, Australia, Australie
6
7
Museum of Zoology, University of Sao Paulo (MZUSP) – Avenida Nazareth, 481, 04263-000, Ipiranga,
São Paulo, SP, Brazil, Brésil
8
Observatoire Séries Faune-Flore UMS 3113 – Institut Universitaire Européen de la Mer (IUEM) –
Technopôle Brest Iroise, Rue Dumont d’Urville, 29280 Plouzané, France
Bioturbation has important effects on intertidal sediment structure and biogeochemical functioning. Bioturbation activities of benthic fauna, through creation of burrows and sediment
reworking, extend the sediment-water interface over which solute exchanges occur and enable
translocation of particles to different depths, thus altering the nature and quantity of resources
available for microorganisms, fauna and plants. The bioturbation ‘performance’ of a species may
be affected by abundance, body size as well as external environmental factors. Whilst individual
species have been studied in great detail, the role of a benthic community comprising multiple
species in ecosystem functioning remains comparatively unknown in mangroves, especially in
French Guiana.
Mangroves in French Guiana grow rapidly in adaptation to recurrent sedimentary perturbations
caused by sediment inputs from the Amazon River. They colonize mud banks which migrate
along the coast leading to the establishment of young mangroves followed by several stages of
mangrove development. How benthic fauna community structure and bioturbation activities are
related to mangrove growth was addressed in this study. Specifically, the latter aimed to (1)
characterize the changes in sedimentary conditions, (2) describe the benthic faunal community
structure (3) and quantify their bioturbation activities along a mangrove growth gradient. Three
stages of mangrove development were thus investigated (i.e., bare mud, pioneer mangrove and
∗
Intervenant
24
young mangrove) in the Sinnamary estuary. In each of these stages, vegetation structure and sediment parameters were studied. Two distinct sampling strategies were adapted to the sampling
scale required for the analysis of community structure and bioturbation activities of the macrofauna and megafauna (crabs). Macrofauna was recovered from sieved sediment cores whereas
the crabs were caught from quadrat plots in order to quantify their abundance, biovolume and
diversity. Inert fluorescent particles (i.e., microspheres) were added at the sediment surface of
additional cores. The amount of sediment buried by the macrofauna was then quantified by
analyzing fluorimetrically the profiles of microspheres in each core. In parallel, the sediment
excavated by crabs for burrow maintenance and pellets resulting from feeding activity were collected to estimate the rate of sediment processed by the megafauna.
Our results showed that the benthic faunal community exhibited structural and functional
changes as mangrove colonization and growth progressed. Change in species diversity from bare
to vegetated muds is accompanied by an increase of the biovolume:abundance ratio indicating
larger body sizes in the young mangrove stands than in earlier stages of mangrove developments.
Such changes are associated with an increase of the rate of sediment reworking (from ca. 20
to 180 g dw/m2 /tidal cycle) and of the diversity of functional groups (biodiffusors, regenerators, conveyors, gallery-diffusors) in the vegetated sediments. Maximum sediment reworking
rate:biovolume ratios are found in the pioneer mangrove stage for both the macrofauna and the
megafauna suggesting the benthic community is highly efficient in processing sediment at the
time of mangrove establishment. Overall, the present study provides insights into the functional
roles and their variations, through sediment reworking activities, of benthic faunal groups for
ecosystem
functioning
duringcommunity
mangrove structure,
growth. functional groups, sediment reworking, mangroves
Mots-Clés:
bioturbation,
25
Mangrove Rehabilitation Weg naar Zee Using
Sediment Trapping Technique
Sieuwnath Naipal
∗† 1
, Steven Gaines 2 , Christa Fung A Loi
3
1
Anton de Kom University of Suriname, Faculty of Technological Sciences, Department of
Infrastructure – Faculty of Technological Sciences, Department of Infrastructure, Suriname
2
Rockbridge Community Forestry, LLC. – Rockbridge Community Forestry, LLC. Lexington, Virginia
USA, États-Unis
3
Anton de Kom University of Suriname, Faculty of Technological Sciences, Department of
Infrastructure – Anton de Kom University of Suriname, Faculty of Technological Sciences, Department
of Infrastructure, Suriname
Coastal areas subjected to the clearing of mangroves are increasingly vulnerable to strong
waves and subsequent erosion. Weg naar Zee resort of Paramaribo is one example, with continuous loss of land over several kilometers of coastline, spanning over a time period of two
decades and counting. Increased flooding, and subsequent damage to crops and infrastructure
are among the impacts putting a burden on the existence and security of coastal communities
and biodiversity. To mitigate this burden, now and in the future, rehabilitation of mangrove
communities is needed to increase coastline resilience. In the case of Weg naar Zee resort, a
sediment trapping unit has been constructed and implemented in the mud bank to harvest sediment travelling through ocean water. This study hypothesizes that sediment deposition will be
increased as a result of the sediment trap. Increased sedimentation will stimulate the growth and
rehabilitation of mangrove communities, which in turn, will halt or reverse the ongoing erosion
pattern. As a result, biodiversity and the well-being of the coastal community will be increased.
This article describes the methodology used in establishing such a sediment trapping unit, the
observed
preliminary
results,
future projections.
Mots-Clés:
climate
change,and
deposition,
erosion, mangroves, mitigation, sea level rise, sediment
∗
†
Intervenant
26
Sedimentary biogeochemical cycling in the
Amazon- Guianas mobile mud belt: an
overview.
Robert Aller
1
∗ 1
The vast Amazon-Guianas dispersal system provides an important model for understanding
elemental cycling along energetic muddy coasts in the modern, ancient, and future ocean. The
flux of sediment from the Amazon River, together with inner shelf currents and waves generated by the Trade winds, drive the continual migration of shore attached mudbanks towards
the Orinoco delta. At any given time and location, each mudbank is composed of multiple
sedimentary facies with distinctive biogeochemical properties. The system as a whole, however,
behaves as a steady advective mud stream and biogeochemical line source – sink interacting
with the larger tropical Atlantic Ocean. Thus, on a wide spectrum of time-space scales, the
coast is a fully 4-dimensional, dynamic reactor. Incorporation of water column plankton, microphytobenthos, and eroded mangroves into the advecting mud promotes extraordinarily high C
remineralization rates and fluxes generally dominated by the marine sources. The mudbelt is a
highly efficient sedimentary incinerator retaining relatively little residual organic C downstream
of the Amazon delta. Despite high C remineralization rates, suboxic Fe reduction – reoxidation
dominates diagenetic properties in fluid and reworked muds, reflecting delivery of weathered
material from the tropical Amazon drainage basin and frequent remobilization –reexposure to
oxygenated water during transport in the dispersal system. The multiple diagenetic facies within
a mudbank complex are derived from the migrating suboxic source material with common initial
biogeochemical properties that are progressively modified during algal mat formation, bioturbation, evaporate deposition, and mangrove colonization and growth. Relatively stabilized deposits
become increasingly sulfidic, punctuated by oxygenated macrofaunal burrows and mangrove rhizospheres. In addition to intense C and nutrient cycling, authigenic clays and carbonates are
continually generated during early diagenesis. For example, the distribution of cosmogenic 32Si
(t1/2 = 140 yrs) indicates that the Amazon-Guianas mudbelt is a sink for _~0.3 Tmol Si/ yr as
authigenic clay, equivalent to _~ 38% of the Amazon River input of dissolved Si to the Atlantic.
The impacts of this system on global biogeochemical cycling are closely tied to Amazon drainage
basin properties, coastal sedimentary dynamics, the Atlantic climate-related wave field, and shelf
– open
ocean water
exchangebiogeochemistry,
processes.
Mots-Clés:
Sedimentary
diagenesis, nutrient cycling, mangrove biogeochemistry,
mudbank dynamics, shelf, ocean exchange
∗
Intervenant
27
Changing times for mangroves as temperatures
rise. Changing phenologies!
Norman Duke
1
∗† 1
Centre for tropical water and aquatic ecosystem research, Australia. – Centre for tropical water and
aquatic ecosystem research, Australia., Australie
In this presentation, I bring attention to the mostly unreported changes taking place in local
mangrove stands, driven by increasing temperatures.
Despite being a numerically small group of around 80 plants, mangroves display a remarkable
diversity of phenological differences; as variable as the relatively large number of genotypes and
derivative families. These differences are exemplified by distinctive dates of peak flowering and
propagule maturation for respective species, dependant also on their individual location and
geography. The changes are further manifest in leafing, shown most visibly by the only deciduous mangrove, Xylocarpus mollucensis. This unusual mangrove produces outstanding orange to
red canopy foliage each winter, shedding all leaves before flowering and leafing a month later –
making this species perhaps the only candidate for tracking seasonal changes in mangroves using
satellite imagery!
A key inference from such notably seasonal patterns, is that the functioning of mangrove plants,
like other plants, are driven by, and decidedly influenced by temperature. And, it is further likely
that such processes have profound affects on distributional endpoints, as barriers to dispersal.
Therefore, as temperatures increase, this will result in not only changes to phenological events,
like dates of peak leafing, flowering or fruiting, but also result in shifts of individual and distinct,
high latitude distributional limits for respective species.
While we acknowledge that global temperatures are increasing, and that phenological patterns
are primarily linked to temperature, then there needs to be urgent attention given to key questions like: what are the changes taking place in mangrove plants; how important are these
changes; and, what are the direct and indirect consequences of such changes?
Evidence of precise phenological times are mostly lacking, but there are a few detailed observations from which we can infer likely changes affecting all mangrove habitats. To demonstrate
these key influences, I review a case study assessment of Avicennia marina before presenting
deductions relevant to Atlantic Avicennia species, as those in French Guiana.
Mots-Clés: mangroves, phenology, climatic change
∗
†
Intervenant
28
Vulnérabilité des paysages littoraux et
des eaux côtières, impact sur les
ressources associées
29
Environmental Sensitivity of Coastal
Ecosystems from the Perspective of Oil
Exploration: The Mouth of the Amazon
Valdenira Santos
2
∗ 1
, Amilcar Mendes
, Odete Fátima Silveira
3
4
5
∗
, Zanandrea Figueira
, Luis Takiyama
1
1
, Laysa Santana
∗
∗
∗
, Arthur Miranda
∗
, Francinete Facundes
1
∗
∗
, Catherine Prost
6
2
, Erica Jimenez
∗
, Ronaldo Almeida
∗
∗
1
1
Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá, Núcleo de Pesquisas Aquáticas
- IEPA/NuPAq (IEPA) – Rod. JK, km 10, 68902-280, Fazendinha, Macapá, Amapá, Brésil
2
Museu Paraense Emílio Goeldi - Coordenação de Ciências da Terra e Ecologia (GOELDI/CCET) –
Av. Perimetral, 1901 - Terra Firme - Telefone: 55 91 3075 6272 - Cep: 66077-830 - Belém - PA - Brasil,
Brésil
3
Universidade Federal do Pará (UFPA-FAOC-LIOG) – in memoriam, Brésil
4
Instituto de Pesca do Amapá (PESCAP) – Macapá-AP, Brésil
5
Universidade Federal da Bahia (UFBA) – Salvador-BA, Brésil
6
Ministério do Desenvolvimento Agrário (MDA) – Delegacia Amapá, Brésil
∗
Intervenant
49
30
The offshore sedimentary basins of Foz do Amazonas (FZA) and Pará-Maranhão are the
most recent coastal areas of Brazil to draw the interest of the petroleum industry. Activity is
especially intense in FZA, where the discovery of oil off the coast of French Guiana led to competition between oil companies to acquire exploration blocks. However, oil exploitation activities
in these areas may be particularly problematic due to the peculiar geo-environmental conditions
and high vulnerability of coastal and marine ecosystems in the Amazon region, generating major
challenges for coastal management. Specifically, macrotidal semidiurnal, strong currents interact
with the Amazon River dispersal system and a wide, shallow continental shelf to trigger high
intensity marine and coastal processes. The effects are further exacerbated by trade winds that
blow constantly towards the coast. Given the recent intensification of oil exploration activity,
understanding these geophysical processes and how they influence the potential vulnerability of
different areas to oil spill is an essential first step towards effective environmental management.
One of the main tools to manage environmental risk is the creation of Environmental Sensitivity
Index (ESI) Maps based on oil spill effects. Such maps incorporate biological resources, socioeconomic activities and resource use, and can be used to guide containment efforts and facilitate
oil removal by identifying the most sensitive areas of coastal and marine ecosystems. Here, we
use this methodology to map the environmental sensitivity of the FZA basin to oil spills. The
maps were generated from the Landsat mosaic, OLI sensor for 2013, using the less cloud cover
and low tide criteria. Images were digitally processed and the coastal environments extracted
by applying the object-oriented classification technique. Mapped patterns were validated by a
combination of field data and overflights. In situ biological resources sensitive to oil, economic
activities and the use of coastal resources were also mapped.
The maps were generated at scales compatible with the three levels of response to an accident: strategic (1: 750,000), tactical (1: 150,000) and operational (1: 25.000). Most of the
mapped coastal segments (mangroves, riverbanks and marsh) had maximum values of ESI due
to the presence of highly productive and sensitive ecosystems, and the intensive use of coastal
and maritime areas for artisanal and industrial fisheries.
The greatest environmental challenges of oil exploration activity in the FZA basin is effectively
protecting resources under threat of contamination and the identification of priority areas for
cleaning and protection. The presence of large muddy areas that are both remote and inaccessible is particularly problematic, since they may act as oil traps with considerable potential to
hamper mitigation actions. Moreover, marine currents have the potential to transport sediments
to neighboring countries, creating both environmental and geopolitical problems. More scientific studies are needed to improve knowledge of coastal and marine currents, and to accurately
quantify
the resilience
these sensitive
ecosystems
in caseBasin
of oilofspills.
Mots-Clés:
Maps ofofEnvironmental
Sensibility,
Maritime
Amazon Mouth, Oil Spilling
50
31
Transboundary risks associated with oil and
gas industry in the Northern Brazilian coast
Júlio Pellegrini 1 , Mario Soares ∗† 2 , Felipe Soares 1 , Gustavo Estrada 2 ,
Gabriel Carvalho 1 , Marcelo Cabral 1 , Maurício Fragoso 1 , Leonardo Cruz 1 ,
Francisco Santos 1
1
Prooceano (Prooceano) – Av. Rio Branco, 311 - Centro, Rio de Janeiro - RJ, 20040-009, Brésil
Universidade do Estado do Rio de Janeiro (UERJ) – UERJ, Av. Sao Francisco Xavier, 524,
2
Due to its high biological importance and environmental characteristics, mangroves are considered the marine ecosystem most sensitive to contamination by oil spills.The predominance of
muddy sediments with low levels of oxygen and high concentrations of organic matter, limits oil
degradation capacity. Also important is the fact that this ecosystem occupies sheltered areas
with low marine energy and reduced capacity of physical removal of the oil.Thus, by controlling
the persistence of oil in the system, these characteristics strongly affect the resilience of the
ecosystem to oil contamination.
The high vulnerability of mangrove forests to oil contamination is associated both to the sensitivity of mangroves species to these pollutants and to the high persistence of the oil in these
environments. However, this vulnerability also depends on the susceptibility to oil spills, that, in
turn, depends on the proximity to potential sources of oil (exploitation areas, transport routes,
oil terminals, refineries and pipelines) and environmental characteristics of the region (oceanographic processes and coastal geomorphology).
The northern Brazilian coast has an area of mangroves of approximately 956,089 ha, which
corresponds to 78% of the Brazilian mangroves.In addition to its great extension, these forests
are also considered those with the greatest structural development and species richness of the
entire Brazilian coast. Furthermore, the mangroves located between São Luis (Maranhão) and
the Amazon River (Pará) comprise the largest continuous mangroves area in the World. However, the dynamics of this region, which is inserted in the Brazilian Equatorial Margin, affects
a wider area, including the mangrove forests and other coastal systems located between Amapá
(Brazil) and Orinoco (Venezuela), as well as part of the Caribbean.
In 2013, the Brazilian National Agency of Petroleum offered several Oil and Gas exploratory
blocks located along the Brazilian Equatorial Margin. The region adjacent to the continental
shelf break and seaward of the 200 m isobaths suffers direct influence of the North Brazil Current,
an intense and persistent current that flows northwestward with mean velocity higher than 0.75
m.s-1. During July and February, a portion of the North Brazil Current separates sharply from
the coast near 6◦-8◦N and retroflects to feed the eastward North Equatorial Countercurrent. In
the continental shelf region, the superficial currents also flow northwestward, but in a much less
∗
†
Intervenant
32
intense manner and subjected to the strong influence of astronomic macrotides.
The analysis of drifters data gave good insights into possible trajectories of oil spill originated
from Oil and Gas exploratory blocks located in the Brazilian Equatorial Margin. The greater
part of observed trajectories was northwestward, reaching oceanic regions adjacent to the Brazilian Equatorial Margin. Along this route, part of these drifters has reached the continental shelf,
where, under less influence of the North Brazilian Current, many drifters were transported towards the coast. Part of the drifters that followed the North Brazilian Current were transported
eastward, under the influence of the North Brazilian Current retroflection, remaining in this direction without reaching the coast even 60 days after they passed through Foz do Amazonas basin.
The observed patterns indicate that oil spills originated in the Brazilian Equatorial Margin
may reach the coast not only in Brazil but also along other South American (French Guyana,
Suriname, Guyana, Venezuela) and Caribbean countries (Trinidad Tobago, St. Lucia, St. Vincent and the Grenadines and Barbados).
Further studies including oil dispersion and fate modeling, considering oil weathering process
and wind drift effects, must be accomplished in order to obtain a more precise evaluation of
oil trajectories and the vulnerability of mangrove forests located along the north coast of South
America
to oil spills.
Mots-Clés:
Mangrove Vulnerability, Oil Spills, Modeling
33
A pesca artesanal como vetor de
desenvolvimento local en Oiapoque (Brasil).
Ricardo Pereira
1
∗ 1
, Viviane Amanajás
∗ †
, Maísa Frazão
∗ ‡
UNIVERSIDADE FEDERAL DO AMAPÁ (UNIFAP) – Brésil
Este estudo apresenta uma abordagem sobre a superposição de múltiplas territorialidades
(conhecimento/identidade) levando a conflitos pelo uso do território de pesca, ameaçando a
atividade pesqueira e o desenvolvimento local. A área de estudo compreende, o município de
Oiapoque, localizado entre o Estado do Amapá (Brasil) e Guiana Francesa (França). Oiapoque
possui parte do seu território sob diferentes tipos de proteção, que abrange as águas costeiras,
com grande potencial de pesca, mas com normativas que regulam os seu uso e acesso. Territorialidades diferentes e sobrepostas, formas de uso dos recursos naturais têm levado ao surgimento de
conflitos entre os vários atores sociais presentes no território, uma vez que têm interesses divergentes. Neste sentido, a pesca desempenha um papel na importância económica, social e cultural
nas comunidades onde atua. Assim, o objetivo deste estudo é investigar os conflitos de pesca
causados pela sobreposição de territórios e territorialidade dos pescadores artesanais e a regulação imposta pelo Estado. Neste trabalho foi adotada como metodologia pesquisa na literatura
sobre o assunto, a pesquisa exploratória e participativa, e a observação direta. Considera-se que
o contato direto com o pescador é uma maneira de obter informações sobre a pesca dentro de seus
próprios contextos locais. Devidos os problemas investigados, o estudo adota uma abordagem
qualitativa
para pesca
analisar
atores conflitos,
sociais, conflitos
desenvolvimento
local
de pesca artesanal.
Mots-Clés:
artesanal,
território,e desenvolvimento
local
e Oiapoque
∗
Intervenant
‡
†
34
Suivi topographique de profils de plages des
trois grandes anses de l’île de Cayenne :
implications sur les flux sédimentaires sableux
des parties émergées et intertidales.
Pierre Bourbon
1
∗ 1
, Ywenn De La Torre 2 , Manuel Moisan
Bureau de recherches géologiques et minières (BRGM) – Direction Régionale Guyane, Domaine de
Suzini, Route de Montabo, BP552, 97333 Cayenne Cedex 2, Guyane française
2
Bureau de recherches géologiques et minières (BRGM) – Guadeloupe
Le littoral de la Guyane est naturellement soumis à des phénomènes cycliques d’érosionaccrétion sous l’influence du passage successif de bancs de vase issus de la décharge sédimentaire
du fleuve Amazone dans l’Océan Atlantique. Dans ce contexte, les variations annuelles de la position du trait de côte sur le littoral sableux de la presqu’île de Cayenne peuvent atteindre 100m
par an. Cette instabilité apporte un certain nombre de contraintes en termes d’aménagement qui
devraient s’accentuer sous l’influence du changement climatique et de l’augmentation du niveau
moyen de la mer. Dans le but de suivre la dynamique de ce littoral, un suivi des plages de l’île de
Cayenne a été mis en place en 2011. Ce dernier consiste à établir des levés topo-morphologiques
au niveau des anses de Montabo, Montjoly et Rémire.
Jusqu’en fin d’année 2012, l’évolution morphologique apparait de manière générale assez modérée
(gains ou pertes en volume[1] inférieurs à 30m3), avec toutefois une alternance de phases érosives
et d’engraissement. La variabilité des pentes des plages considérées, entre 5 et 10 %, semble
corrélée avec le degré d’exposition vis-à-vis des houles dominantes et par conséquent avec les
variations morphosédimentaires observées. Néanmoins, d’une manière générale, les trois anses
étudiées présentent un comportement qui suivent la même évolution sur cette période avec une
tendance à l’engraissement en partie est tandis qu’au centre ou à l’ouest, l’érosion parait plus
marquée.
A partir du mois de novembre 2012, des évolutions plus marquées sont mises en évidence avec des
comportements qui cependant n’apparaissent pas identiques pour les trois anses étudiées, notamment vis-à-vis de la tempête majeure de janvier 2013 (houle de nord/nord-est de 6m de hauteur
maximale). Ainsi, sur la plage de Montabo la tendance antérieure de dérive littorale vers l’est se
confirme avec un transfert de sable de l’ordre de 100m3 entre le centre et l’est de la plage. Un
schéma similaire est mis en évidence au niveau de l’anse de Montjoly avec une perte dans la partie
ouest couplée avec un gain en sable conséquent à son extrémité est, d’environ 350m3 (profil Montravel) En revanche, on observe une autre tendance sur l’anse de Rémire avec des profils en partie
ouest qui évoluent peu lors de cet épisode (disponible sédimentaire déjà très faible sur ce secteur)
et avec un profil fortement déficitaire en partie sud-est avec une perte de 140m3 (profil Gosselin).
∗
Intervenant
35
En octobre 2014, une ” bascule ” semble s’initier au niveau de l’anse de Montabo avec une
perte de sédiment côté est au profit du secteur ouest. Ce phénomène apparait cependant de
courte durée avec une tendance au retour à l’accumulation de sable à l’extrémité est révélée lors
des derniers levés en mai 2015.
La tempête de 2013 constitue un forçage majeur sur la période de mesure avec un déplacement important et généralisé vers l’est du sable sur l’ensemble des trois anses. Des tendances
ponctuelles au retour vers l’ouest sous l’effet du phénomène de rotation de plage sont toutefois
observées sans qu’une alternance saisonnière ne soit clairement établie. La poursuite des levés
permettra d’identifier les évolutions de ces transferts sédimentaires, notamment dans le contexte
de l’arrivée d’un nouveau banc de vase sur l’île de Cayenne depuis l’est via le contournement
de l’embouchure du Mahury. Par ailleurs, les échanges de sable avec la partie immergée de la
plage resteront à éclairer. La poursuite des mesures topobathymétriques et l’interprétation des
données de l’évolution du trait de côte et des relations de causes à effets avec les données de
houles qui seront réalisés dans le cadre de l’Observatoire de la dynamique côtière de la Guyane
devraient permettre de préciser ces différents aspects.
Volume calculé sur un unique profil en considérant de manière arbitraire une largeur égale à 1m.
Mots-Clés: érosion, accrétion, flux, sédiments, dynamique, profils, plages, topographie, morphologie, évolution, trait de côte, Guyane, Cayenne, Rémire, Montjoly, Montabo
36
La dynamique côtière de l’ouest guyanais
Johan Chevalier
1
∗ 1
Réserve naturelle de l’Amana – Guyane française
La réserve naturelle de l’Amana couvre les 60 kilomètres du littoral à l’Ouest de la Guyane.
Depuis la création de la réserve en 1998 cette zone est soumise à une très forte érosion : environ
1 200 hectares de terre ont disparu, soit près de 15% de la superficie terrestre de la réserve.
Face à cette situation, la RN de l’Amana initie une collaboration avec des équipes du CNRS afin
de mieux décrire et comprendre ce phénomène. Cette présentation vise à faire un point sur la
dynamique du littoral, notamment l’érosion dans l’ouest guyanais, à présenter ses implications
socio-économiques ainsi que les perspectives sur ce territoire.
Dans le cadre d’une thèse, le CNRS a réalisé récemment un suivi du recul du trait de côte sur les
plages bordant les rizières de Mana. Sur la zone d’étude, le retrait de la plage a été de 50 m en 6
mois. Il s’agit d’un des taux de recul les plus importants au niveau mondial. L’impact de cette
érosion est considérable tant au niveau économique qu’écologique. En effet, depuis l’ouverture
des rizières sur la mer en 1999-2000, 900 hectares de parcelles ont disparu (soit 16,5% de la
surface totale en rizière à l’Est du pont de Mana) et du fait des entrées d’eau salée une partie
importante des parcelles restantes est devenue inexploitable. De même entre les rizières de Mana
et la crique Organabo, 924 hectares de milieux naturels remarquables ont disparu entre 1999 et
2013 avec un impact très important sur la faune associée à ces habitats.
Sur la plage de Yalimapo, les travaux réalisés ces dernières années dans le cadre d’une autre
thèse menée au CNRS ont mis en évidence une érosion de l’ensemble de la plage, avec un recul
du trait de côte de 5 à 15 m selon les zones entre 2011 et 2014 et une perte moyenne d’environ 1
m de hauteur de sable sur la plage. Sur certaines zones, comme le site de Simili, le recul du trait
de côté est particulièrement important : environ 10 m en moins d’une année (de mai 2013 à mars
2014) avec une perte de près de 3 m de hauteur de sable sur la plage. L’impact écologique de
cette érosion est sensible car il implique un très net déclin de la qualité de ce site pour la ponte
des tortues marines et potentiellement un abandon progressif de cette plage par ces espèces. La
plage de Yalimapo et la ponte des tortues marines étant un des atouts touristiques importants
de la commune de Awala Yalimapo cette évolution risque d’avoir un fort impact économique. Au
cours des dernières années, l’érosion a d’ailleurs conduit à la destruction de certains aménagements d’accueil des visiteurs. De plus le village de Yalimapo étant situé à proximité immédiate
de la plage, la poursuite du phénomène pourrait menacer jusqu’à l’existence même du village.
Ces observations récentes corroborent les travaux réalisés par Créocéan-BRL en 2008 ; le taux de
recul observé sur la zone des rizières s’accélère depuis 2006 avec des vitesses d’érosion entre 140
et 160 m par an sur certaines zones. La poursuite de cette période d’érosion particulièrement
importante est donc très inquiétante, d’autant qu’aucune donnée actuelle ne nous permet de
pronostiquer une inversion de la tendance ou même une stabilisation du littoral dans les années
à venir (arrivée d’un important banc de vase par exemple).
∗
Intervenant
37
Si la phase d’érosion actuelle est probablement en grande partie d’origine naturelle, il semble
que ce phénomène soit amplifié, peut être largement, par certains aménagements humains. Ainsi
les canaux des rizières perpendiculaires à la côte et les casiers dépourvus de végétation semblent
faciliter le processus d’érosion. Par conséquent, la mise en œuvre de certaines actions de gestion
telles que le comblement des canaux proches de la côte ou la favorisation de la mangrove dans
les casiers littoraux permettrait probablement de limiter l’érosion sur cette zone. Face à cette
situation il nous semblerait important de discuter de la faisabilité d’actions techniques visant à
limiter
ces facteurs
amplifiant
de l’érosion afin de préserver ce territoire.
Mots-Clés:
Erosion,
Mana, l’impact
Awala Yalimapo
38
Savanes de Guyane : anthropologie des
controverses sur le devenir de paysages
culturels
Marianne Palisse
∗ 1
1
Centre de recherche sur les pouvoirs locaux dans la caraibe (CRPLC) – CNRS : UMR8053, Université
des Antilles et de la Guyane – Campus univ. de Schoelcher - BP 7209 97275 SCHOELCHER CEDEX,
France
Les savanes sèches de Guyane française représentent moins de 0,3 % du territoire. La plupart
d’entre elles sont situées sur la bande côtière récente, et sont à proximité de la principale route,
la nationale 1, ce qui les rend particulièrement vulnérables. Ces dernières années, les institutions
de protection de l’environnement et les associations écologistes s’inquiètent de voir les surfaces
de savane diminuer et cherchent des moyens de préserver la biodiversité attachée à ces milieux,
qui est jugée exceptionnelle par les spécialistes.
La recherche anthropologique présentée dans le cadre de cette communication a été menée à
Sinnamary et à Iracoubo. Elle a permis de mettre en évidence la profonde imbrication des questions sociales et environnementales concernant les savanes et le caractère politique des débats
sur leur avenir. Les savanes sont depuis longtemps fréquentées par les populations créoles et
amérindiennes vivant à proximité qui s’y livraient jusqu’à récemment à des pratiques diverses :
culture, élevage, chasse, pêche et cueillette. Ces pratiques, liées pour certaines à la technique du
brûlis, avaient une influence sur les milieux. Elles tendent cependant à disparaître ces dernières
années avec les changements de mode de vie et l’exode rural. Or, cette disparition a des conséquences visibles sur de nombreuses zones de savanes qui s’embroussaillent. Dans le même
temps, d’autres modèles agricoles sont apparus en savanes, en particulier de nouvelles formes
d’élevage bovin, qui supposent d’amender les sols et de semer des herbes à pâturage, ce qui a
pour conséquence de transformer profondément la biodiversité. Les savanes sont aussi affectées
par l’apparition d’espèces invasives, parmi lesquelles on peut citer acacia mangium, initialement
utilisé pour restaurer les sites miniers en forêt, et dont le feu favorise la germination.
Il s’avère aujourd’hui que pour préserver la biodiversité des savanes, empêcher certaines pratiques ne suffit pas. Il faut mettre en place des modes de gestion permettant notamment de
limiter l’enfrichement. Or, pour les différents acteurs en présence – habitants, agriculteurs,
agents des administrations, militants associatifs -, cela suppose de trouver des compromis sur les
questions qui font polémique. Faut-il autoriser le brûlis ? Faut-il favoriser la transformation de
certaines savanes en pâtures ? Ces interrogations provoquent des débats qui révèlent des perceptions différentes du territoire, mais aussi du rôle de l’homme et de sa légitimité à transformer les
milieux qu’il habite. La controverse s’étend à la question de l’appropriation du foncier, qui est
récurrente en Guyane, dans la mesure où les anciens usages des savanes étaient très largement
fondés sur une appropriation collective du territoire, tandis que les nouveaux sont généralement
liés à une appropriation individuelle et privative de la terre.
∗
Intervenant
39
Enfin, il est intéressant d’observer que la question des savanes suscite l’apparition de collectifs
qui dépassent les frontières culturelles. Ainsi, si les environnementalistes fondent avant tout
leur action sur la nécessité de préserver la biodiversité pour elle même, les habitants créoles et
amérindiens, plutôt éloignés de cette préoccupation, expriment cependant le désir de transmettre des savoir-faire et des pratiques liées au milieu savane. Aussi, malgré les divergences, ces
deux groupes peuvent trouver un terrain d’entente autour du souhait de conserver de ” vraies ”
savanes.
Mots-Clés: Savanes, anthropologie, biodiversité, agriculture, élevage, espèces invasives, controverses
environnementales
40
An Investigation of the Impact of Global Sea
Level Rise Guyana’s Coastal Zone and the
Current Adaptive Capacity
Paulette Bynoe
1
∗† 1
University of Guyana – School of Earth and Environmental Sciences Leslie Cummings Building
University of Guyana Turkeyen Campus Greater Georgetown, Guyana, Guyana
Sea level rise is one of the most significant impacts of global climate change on many low lying developing States such as Guyana. The Intergovernmental Panel on Climate Change Fourth
Assessment Report (IPCC AR4) indicates that sea level is projected to rise between the present
(1980 to 1999) and the end of the 21st century (2090 to 2099) under the six SRES scenarios1 by
between 18 and 59 centimetres. According to the Guyana Second National Communication, projections of sea level rise (using the HadCM3 and the CGCM2 scenarios for the years 2031, 2051
and 2071) vary from 14 cm (HadCM3) to 26 cm for 2031 using the CGCM2, while for 2051 the
sea-level rise is projected from 21 cm (HadCM3) to 43 cm (CGCM2), and from 25 cm (HadCM3)
to 51 cm (CGCM2) for the year 2071. Given Guyana’s geomorphologic structure, the narrow
coastal plain (coastal zone) is expected to be mostly affected. This area is currently inhabited
by approximately 90 percent of the national population, has the Capital City of Georgetown,
good agricultural lands, almost all the major towns and ports, relatively well developed public
infrastructure, fragile coastal ecosystems, as well as administrative and political centres of the
country.
This study will utilise a mixed methods approach to apply the data collection techniques of desk
review of literature (reports, technical studies reports, national documents, among others), a
survey of two selected coastal communities, and in-depth interviews of key informants such as
representatives of government agencies (including Office of climate Change, Civil Defence Commission, Ministry of Public Infrastructure and Ministry of Agriculture), civil society (Habitat
for Humanity, Red Cross Society, Guyana Association of Professional Engineers, Private Sector
Commission, University of Guyana lecturers) and international organisations (Inter-American
Development Bank, United Nations Development Programme, and the European Union) to
analyse (i) the environmental, social and economic impacts of floods (associated with increased
intensity and frequency of rainfall/precipitation, plus overtopping of sea defences due to high
tides) and (ii) the vulnerability and capacity (physical, eocnomic and institutional) of communities to respond to this hazard. Importantly, a simple flood hazard profile of Guyana’s coast will
be attempted, with the aid of GIS technology.
The study will conclude with concrete recommendations (adaptation practices and options) that
could be implemented to mitigate flood risks at the household, community and national levels
in Guyana
and have
theofpotential
ofLevel,
beingGuyana,
replicated
in the capacity
Guianas.
Mots-Clés:
Impact
Global Sea
Adaptive
∗
†
Intervenant
41
Espèces emblématiques, indicatrices et
à valeur halieutique. Réseaux
trophiques et contaminants
42
Scénario d’impact du changement climatique
sur la pêche côtière et la biodiversité
halieutique
Fabian Blanchard
∗ 1
, Oscar Prado-Merini , Abdoul Cissé , Luc Doyen
1
ifremer – Guyane française
A l’échelle mondiale, face à la perte et à l’érosion de la biodiversité marine dues aux impacts
de la surexploitation des ressources, aux altérations des habitats, au changement climatique,
aux espèces invasives et à la pollution, l’approche écosystèmique pour la gestion des ressources
halieutiques est prônée.
Le Système d’Informations Halieutiques de l’Ifremer a permis de montrer que la pêche côtière
en Guyane représente actuellement environ 150 navires pour une production totale annuelle estimée autour de 3000 tonnes. Cette production se concentre sur une douzaine d’espèces côtières
de poissons, représentant en moyenne au moins 80% de la production totale. Cette production
est écoulée presque totalement sur le marché local. Toutefois, il existe une pression de pêche
supplémentaire exercée par des flottilles côtières d’origine étrangère pêchant illégalement dans
les eaux guyanaises (pêche INN). Les données de l’Action de l’Etat en Mer ont permis de mettre
en évidence l’importance de cette pression, en termes d’effort de pêche et de production, qui est
supérieure à celle exercée par les flottilles côtières guyanaises.
Par ailleurs, sur le plateau continental guyanais, nous avons pu observer via des campagnes expérimentales de chalutage ciblant les peuplements de la macrofaune de fond que ceux-ci étaient
composés à la fois d’espèces sub-tropicales et d’espèces tropicales. La comparaison de la structure
de ces peuplements entre les années 90 et aujourd’hui a révélé que l’abondance et la biomasse des
espèces sub-tropicales ont diminué, tandis que l’abondance et la biomasse des espèces tropicales
se sont maintenues. Ceci est à mettre en regard du réchauffement des eaux qui est équivalent à
celui observé en Atlantique Nord-Est où d’importantes modifications des peuplements de plancton et de poissons ont pu être attribuées à ce réchauffement.
En Guyane, l’augmentation à long terme de la demande en produits de la mer liée à la croissance
démographique d’une part, et les impacts du changement climatique sur la biodiversité marine
déjà observés d’autre part, posent la question de la capacité de l’écosystème à répondre aux
pressions grandissantes pour assurer la sécurité alimentaire de la population guyanaise, garantir
une viabilité économique des pêcheries sans altération de sa biodiversité et des services écosystémiques associés.
Pour contribuer à répondre à cette question, un modèle bioéconomique de la pêche côtière et des
ressources exploitées est en développement. La dynamique des principales espèces est modélisée,
intégrant leurs interactions trophiques, une croissance dépendant de la température du milieu, et
∗
Intervenant
43
un prélèvement par les différentes flottilles de pêche côtière, y compris la flottille étrangère illégale.
Les simulations réalisées montrent qu’il existe des solutions viables pour la biodiversité et la
rentabilité de la pêche : il serait donc possible de concilier à la fois des objectifs économiques et
écologiques dès lors que l’on ne cherche pas à maximiser les captures et/ou les profits. Toutefois,
l’effort de pêche supplémentaire lié à la pêche illégale induirait une disparition précoce de certaines espèces du milieu. De même, l’effet du réchauffement climatique accélèrerait la disparition
de certaines espèces.
La complexité du modèle le positionne comme exploratoire plus qu’opérationnel. Il conviendrait
donc de poursuivre son développement ainsi que la collecte des données biologiques, écologiques
et économiques pour le paramétrer afin de le rendre de plus en plus opérationnel pour la gestion
et leMots-Clés:
développement
durable
de la pêches.
scénarios,
changement
climatique, biodiversité halieutique, pêche artisanale côtière
44
Is high biodiversity and complex trophic
networks equal to ecosystem stability?: A
comparative study of tropical mangrove
estuaries
Maria Ching Villanueva
∗† 1
1
Laboratoire des Biologies Halieutiques, IFREMER Centre de Bretagne, Pointe du Diable BP 70,
29280, Plouzané (Ifremer) – IFREMER – Laboratoire des Biologies Halieutiques, IFREMER Centre de
Bretagne, Pointe du Diable BP 70, 29280, Plouzané, France
Tropical mangrove estuaries are highly productive and complex ecosystems. Estuaries are
fragile ecosystems that are continuously experiencing seasonal hydrodynamic,
geomorphological and ecological changes. These ecosystems are hotspots of biological,
ecological and anthropogenic activities as they provide numerous and significant ecosystem
services. Species occurrence and distribution rely mainly on their capacity to adapt in short or
long-term hydrodynamic and/or anthropogenic-driven changes.
For this study, tropical estuaries in two different continents (Africa and Latin America) were
compared as to their ecosystem structure, functioning and dynamics. Highest trophic level is
close to 4 although in some areas of the estuaries. It is observed that trophic levels decrease
and energetic links either weakens or simplifies between functional groups as a response to
severe environmental and anthropogenic stresses. Mangroves not only provide shelter and
refuge for many estuarine species but also provide considerable primary production sources
that support many functional groups at higher trophic levels, especially when low
phytoplankton levels are observed. Zooplankton and some crustaceans play significant roles
in transferring energy from trophic level 1 to higher trophic levels. Distribution and
occurrence of these secondary consumers are highly conditioned by environmental factors
(i.e., temperature and salinity). In case of severe environmental conditions (i.e., water
hypersalinity, high turbidity, low primary productivity etc.), specialist ecological groups are
replaced by either detritivorous or omnivorous species.
In this study, ecosystem-based indicators were also estimated and compared to determine
ecosystem health and stability. High biodiversity seems to not always lead to an ecosystem’s
stability. In some highly stressed areas in these estuaries, trophic functioning and stability are
maintained through the simplification or shortening of food web links due to biodiversity
decline.
Mots-Clés: tropical estuary, food web, ecosystem indictors, species’ trophic adaptation, climate
change, trophic guilds
∗
†
Intervenant
45
Dynamique spatio-temporelle du peuplement
de larves de poissons dans l’estuaire du
Mahury (Guyane).
Yann Rousseau
1
∗ 1
CNRS Guyane, USR 3456 – CNRS : USR3456 – Résidence Le Relais 2 avenue Gustave Charlery
97300 Cayenne, France
Peu d’études ont été menées sur les communautés larvaires de poissons entre l’estuaire de
l’Amazone et le delta de l’Orénoque, les deux plus grands fleuves d’Amérique du Sud. En
Guyane française, les côtes sont sous influence amazonienne qui sont à l’origine d’un système
dynamique unique au monde de vasières et de mangroves mobiles. Compte-tenu de l’importance
des pêcheries pour la population guyanaise (3ème secteur économique), la présente étude s’est
focalisée sur la structure et la dynamique de l’ichtyoplancton de l’estuaire du Mahury. Des données ont été récoltées sur trois sites de mangroves situés en haut, au milieu et en bas d’estuaire.
Sur chacun des sites, des échantillonnages mensuels ont été réalisés de février 2014 à janvier
2015. Des paramètres environnementaux (température, salinité, oxygène dissous, pH et turbidité) ont été mesurés in situ avec une sonde multiparamètre ExO2. Les larves de poissons ont été
prélevées à l’aide d’un filet à plancton de 500 µm de mailles couplé à un débitmètre. Ce filet a
été tracté horizontalement sous la surface à marée descendante, pendant les périodes de nouvelle
lune. L’analyse des variables environnementales ont permis de mettre en évidence que la salinité
et la turbidité fluctuaient de manière significative dans l’estuaire (indépendamment des saisons).
Par conséquent, la structure du peuplement larvaire a principalement été analysée en fonction
d’un gradient de salinité. Près de 43 000 larves et post-larves ont été recueillies, appartenant à 12
ordres, 29 familles et 67 taxa. Une densité moyenne de 132 individus pour 100 m3 a été observée
sur la période d’étude mais une très grande variabilité a été constatée au cours de l’année (varie
entre 0 et 1385 ind.100 m-3) et selon le site (du haut vers le bas de l’estuaire, respectivement
106, 101 et 190 ind.100 m-3). Comme pour d’autres communautés de poissons estuariens, la
communauté observée est dominée numériquement par un faible nombre d’espèces. La famille
des Engraulidae domine le peuplement, représentant 33,0% (8 espèces) du nombre total de larves
récoltées, suivie par les Gobiidae (21,1%, cinq espèces), les Eleotridae (19,5%, quatre espèces) et
les Sciaenidae (10,5%, huit espèces). Les taxa les plus abondants sont des espèces estuariennes
; une espèce d’Eleotridae Eleotris sp.1, l’anchois Anchoviella lepidentostole et le gobie Ctenogobius stigmaticus comptabilisant à eux trois 47,2% des captures totales. Seules quelques espèces
marines semblent utiliser la mangrove comme site de nursery en Guyane. Cependant, un gradient
dans la structure du peuplement a pu être observé entre les 3 sites. En faisant abstraction des
espèces estuariennes, le site en haut d’estuaire présente des espèces plutôt associées à des conditions d’eau douce, alors que le site en bas d’estuaire possède des espèces ayant des affinités plus
prononcées pour des conditions marines. Les densités de la plupart des espèces sont d’avantage
influencées par le site que par la saison, le site en bas d’estuaire ayant les densités maximales.
∗
Intervenant
46
Les tendances temporelles des espèces dominantes semblent être influencées en grande partie par
les caractéristiques de leur cycle biologique (période de reproduction). Cette étude se poursuit
actuellement en s’étendant à d’autres estuaires répartis sur l’ensemble du territoire (environ 450
km Mots-Clés:
de côtes) de Ichtyoplancton,
manière à avoirmangrove,
une vision
générale
des communautés
de larves.
estuaire,
variabilité
spatio, temporelle,
Guyane
47
Environmental contaminants, oxidative stress
and virus outbreaks in frigatebirds from
French Guyana
Manrico Sebastiano ∗† 1 , Paco Bustamante , Igor Eulaers , Adrian Covaci ,
Malarvannan Govindan , Benoît De Thoisy , Pierre Blevin , Marcel Eens ,
David Costantini , Olivier Chastel
1
University of Antwerp (Universiteit Antwerpen) – Belgique
An organism’s physiological equilibrium is critically reliant on its immune system,
which provides protection against parasites and pathogens and allows recovery from injuries.
There are, however, circumstances under which the immune system is suppressed, making the
organism particularly sensitive to infections. For example, host exposure to environmental
stressors can facilitate the spread, persistence or emergence of diseases or parasites. Such
stressors can be food shortage, increased ambient temperature or environmental contaminants.
Among them, mercury (Hg) is one of the most toxic trace elements affecting wildlife since it
can impair reproduction and disrupt physiology. Human activities, such as coal burning and
illegal gold-mining have increased the release of Hg in the environment, which has become a
major issue in the Amazon basin. Legacy Persistent Organic Pollutants (POPs), as well
emerging contaminants are also present in marine biota, and pause threat to wildlife through
their impact on physiology, behaviour and fitness. However the relationships between
contaminants, immune capacity and disease outbreaks are not well understood. Vertebrates
translate environmentally stressful stimuli into secretions of stress hormones
(glucocorticoids), which activate the physiological stress response. Chronic exposure of
vertebrates to glucocorticoids is also known to induce oxidative stress (OS) through the
increase in production of free radicals and oxidative damage. OS is a complex multifaceted
biochemical stressor for cells, which occurs when there is an increase in oxidative damage to
biomolecules and oxidation of organic molecules that regulate the cell oxidative balance.
Herpes virus infection may be facilitated by a cell state of OS, while increased intake of
antioxidants might prevent replication of the virus. However, it is unclear whether OS is a
mechanism promoting herpes virus infection. Since 2005, a population of Magnificent
frigatebirds Fregata magnificens, a large tropical seabird breeding on Ile du Grand
Connétable, French Guyana, is regularly infected by a herpes virus strain that is likely
indigenous to frigatebirds. Field observations have reported a morbidity rate up to 80-90% in
infected frigatebird chicks. This unique situation offers a rare opportunity to study in deep
relationships between contaminants, immune capacity and disease outbreaks in a free-living
vertebrates. The aim of this talk is to provide the first data on contaminants exposure (Hg,
organochlorine pesticides and PCBs) in adults and chicks of Magnificent frigatebirds from
French Guyana. We will discuss the possible role of the ongoing contamination of heavy
∗
†
Intervenant
48
metals and/or POPs as a mechanism promoting a chronic stress state, which might trigger the
switch
from a latent
to a virus
productive
viruscontaminants/
infection.
Mots-Clés:
mercury/
outbreaks/
persistent organic pollutants
49
The influence of mesoscale features on the
distribution and the diving behavior of sea
turtles nesting in French Guiana
Philippine Chambault
1
2
∗ 1
, Yvon Le Maho 2 , Damien Chevallier
2
Institut Pluridisciplinaire Hubert Curien (IPHC) – CNRS : UMR7178, université de Strasbourg –
France
Département Ecologie, Physiologie et Ethologie (DEPE-IPHC) – CNRS : UMR7178, université de
Strasbourg – 23, rue Becquerel 67087 Strasbourg Cedex 2, France
Driven by complex physical and biological processes, the marine environment is highly heterogeneous leading to resources partitioning at different spatial and temporal scales. To adapt to
such patchiness, sea turtles have developed migration strategies from their nesting sites to their
foraging grounds. In most nesting sites, the lack of resources associated with the energy required
for oviposition constrain turtles to minimize their energy expenditure and stop feeding during
the egg laying season. To replenish the body reserves after this energy-demanding period, sea
turtles may migrate in areas under the influence of mesoscale features (eddies, fronts, etc.) and
then forage in highly productive habitats in order to maximize their foraging efficiency. Assessing the dispersal movements and the habitat used by migrating animals is a key component to
understand their ecology and implement adequate conservation policies, especially when dealing with vulnerable or endangered species. By hosting each year thousands of gravid females,
French Guiana is one of the major rookery of the North-eastern coast of South America for three
of the seven sea turtles species of the world i.e. green turtles (Chelonia mydas), olive ridley
(Lepidochelys olivacea) and leatherback (Dermochelys coriacea). Under the influence of tides,
the Amazon River plume and oceanic currents, the Guiana’s region is one of the world’s most
dynamic ecosystem, leading to specific environmental and hydrodynamic conditions. Therefore,
this study aims to identify the environmental factors affecting the distribution and the diving
behavior of sea turtles during the migration period. Fifty-six satellite tags we therefore deployed
on adult females in French Guiana and Suriname to inform both on their ecology (on-land and
at-sea) and on the oceanographic conditions encountered during their displacements. This large
dataset will provide detailed and complete knowledge on the ecology of the sea turtles nesting
in French Guiana since three two species have different diet and use diverse ecological niches at
sea. Mots-Clés: sea turtles, migration, foraging behavior, mesoscale activity, habitat use
Méthodes, outils, modèles. Sous-session
Modèles économiques
∗
Intervenant
50
Vulnerability versus resilience of small-scale
fisheries in French Guiana
Luc Doyen
1
∗ 1
CNRS (GREThA) – Centre National de la Recherche Scientifique - CNRS, Université de Bordeaux –
France
Reconciling food security with biodiversity protection is among the greatest challenges of the
century. The case of fisheries and marine ecosystems is especially challenging in that regard.
Marine and coastal ecosystems are experiencing accelerating changes with some alarming trends
(extinctions, depletion, ...). Part of these vulnerabilities in biodiversity is due to fishing pressure. These changes in marine biodiversity in turn impact ecosystem services as emphasized by
the current stagnation or decline of global catches despite continuous increasing fishing efforts.
These trends raise key concerns in relation to food security, especially for developing countries
with high demographic pressure. In this perspective, the sustainable management and the resilience of tropical small-scale fisheries is a key issue.
However the conventional approaches for operationalizing sustainability based on MSY, MEY
or the ICES precautionary approach, were globally unable to prevent over-exploitation and fishing overcapacity worldwide. By considering each exploited species separately, these approaches
often fail to account for the multi-species and multi-fleet interactions which play an important
role. The need for Ecosystem-Based Fisheries Management (EBFM) advocating an integrated
management of marine resources is now widely accepted. Such a muti-objectives framework first
requires to account for the complexity of ecological mechanisms that encompass community dynamics, trophic webs, geographical processes and environmental uncertainties (habitat, climate).
Furthermore, by putting emphasis on sustainability, this approach strives to balance ecological
and economic objectives for present and future generations and to handle a large range of goods
and services provided by marine ecosystems. However, implementing such an approach remains
challenging. It requires models, indicators, reference points and adaptive management strategies.
The present presentation proposes to use a bio-economic viability framework as a methodological
tool to explore the implementation of the EBFM. Viability modeling is now recognized by a growing number of scholars as a relevant framework for EBFM. Viability theory strives to identify
‘viable’ paths that ensure the simultaneous fulfillment of several desirable objectives over time.
These objectives, represented through a series of constraints that need to be satisfied throughout
time, capture the multi-dimensional nature of sustainability. Furthermore, because it takes into
account uncertainties, stochastic viability approach appears to be a relevant framework to ensure
robust and resilient management.
In that context, the coastal fishery in French Guiana provides a very relevant case-study to apply
the EBFM together with stochastic viability. This fishery is characterized by various complex
features including a high equatorial fish biodiversity impacted by several non-selective fleets and
a strong demographic pressure, which eventually is likely to affect the productivity of the fishery
and its contribution to local food security. This paper applies a stochastic viability approach
∗
Intervenant
51
to this tropical small-scale fishery. The model is multi-species, multi-fleet. It is calibrated over
the period 2006-2010 using monthly catch and effort data from the French Guiana’s coastal
fishery. Using projections at the horizon 2040, different management scenarios are compared
from a viability viewpoint. The analysis shows that viable options can be identified which allow
fishing intensity and production to be increased to respond to food security requirements and
profitability but with minimum impacts on the marine resources.
Mots-Clés: Fisheries, marine biodiversity, ecosystem approach, vulnerability, viability, ecological
economics, scenarios
52
The impact of climate change on the French
Guiana Shrimp Fishery
Bassirou Diop
1
∗ 1
CEREGMIA (CEREGMIA) – Martinique
This paper deals with the biological and economic eects of climatic change on the French
Guiana shrimp shery that appears to be sensitive to environmental factors. We rst test dierent natural growth functions that integrate the sea surface temperature. The Ricker function
seems to best adjust to the available data. We then use the estimates to consider a centralised
resource management system that is undertaken in various scenarios with respect to the sea
surface temperature trends. Under the most plausible scenario according to which the sea surface temperature increases as over the last decades, the results suggest that prots and biomass
respectively decrease and collapse.
Mots-Clés: Resource management, Global change, Temperature.
∗
Intervenant
53
The tragedy of ecosystems in open-access
Jean-Christophe Pereau
1
∗ 1
pereau (gretha) – CNRS : UMR5113 – France
This paper investigates the role played by cooperation for the sustainable harvesting of an
ecosystem. To achieve this, a bio-economic model based on a multi-species Gompertz
dynamics with interspecific relationships and multi-agent catches is considered. A
comparison between the non cooperative and cooperative optimal strategies is carried out.
Revisiting the tragedy of open-access and over exploitation issues, it is first proved how
harvesting pressure is larger in the non cooperative case for every species. Then it is
examined to what extent gains of cooperation can also be derived for the state of the
ecosystem. It turns out that cooperation clearly promotes the biodiversity when the number
of agents is high. By contrast, when the number of agents remains limited, results are more
ambiguous especially if a species by species viewpoint is adopted. However, an indicator is
proposed at the ecosystem scale to highlight the gain of cooperation in the general case.
Numerical
examples
the analytical
findings.
Mots-Clés:
Fish illustrate
war, Ecosystem,
Biodiversity,
Optimization, Nash equilibrium.
Méthodes, outils, modèles. Sous-session
Télédétection
∗
Intervenant
54
Bio-optical properties in waters of the lower
Amazon River
Aline Valerio
1
∗† 1
, Milton Kampel 1 , Jeffrey Richey 2 , Alex Krusche
3
Instituto Nacional de Pesquisas Espaciais (INPE) – Av. dos Astronautas, 1758 Jd Granja, CEP :
12227-010 São José dos Campos - SP, Brésil
2
University of Washington – University of Washington SEATTLE, États-Unis
3
Centro de Energia Nuclear na Agricultura (CENA) – Brésil
Draining an area of _~6.5 million km2,the Amazon basin represents 20% of all the freshwater
discharge to the global ocean, 15% of global terrestrial gross primary production, and _~25% of
the global evasive CO2 gas flux from inland waters. The lower Amazon region, from Óbidos (PA,
Brazil) to the ocean, is hydrologically relevant as it has already received the contribution of all
the major tributaries of the Amazon River: Negro, Madeira, Tapajós and Xingú rivers. Despite
its importance, the lower Amazon River is a region that has not been well studied, due to its
complexity in terms of width of the river and tide influence. This work is part of the Net Ecosystem Exchange of the Lower Amazon (TROCAS) project, that seeks to unravel the sequences of
processes and sources of terrestrially-derived organic matter that culminate in the immense CO2
outgassing to the atmosphere. A preliminary exploration of unpublished data collected in the
study area is presented here, with the aim to support a bio-optical characterization of the lower
Amazon River by remote sensing. Two cruises were carried out in April-May and November
2014. The first cruise TROCAS I coincided with the historic high flow of the Amazon River,
and the second cruise TROCAS II was conducted at low water. Both cruises were conducted
at the Amazon River and also at the Tapajós and Xingú River. At each mainstream station
surface water samples (n = 30) were collected for bio-optical (light absorption coefficients) and
chlorophyll-a concentration measurements. Remote sensing reflectance was measured using an
above-water and in-water radiometers. During the high water season, at the Amazon River, the
acdom(440) ranged between 1.79 m-1 and 2.57 m-1, and S275-295 ranged between 0.0144 nm-1
and 0.0148 nm-1. The acdom(440) and S275-295 at the Tapajós and Xingú River was 1.56 m-1
and 2.46 m-1, 0.0126 nm-1 and 0.0145 nm-1, respectively. The adet(440), at the Amazon River,
ranged between 1.90 m-1 and 4.40 m-1, and the adet(440) at the Tapajós and Xingú was 0.38
m-1 and 0.65 m-1, respectively. Mean chl-a concentration at the Amazon River was 0.97 mg
m-3, and at the Tapajós and Xingú rivers was 34,3 and 5,3 mg m-3 respectively. During the low
water season, at the Amazon River, the acdom (440) varied between 0.70 m-1 and 2.5 m-1, and
S275-295 ranged between 0.0132 nm-1 and 0.0161 nm-1. The acdom (440) and S275-295 at the
Tapajós was 0.58 m-1 and 0.0188 nm-1 and at Xingú River was 0.65 m-1 and 0.0187 nm-1. The
adet(440), at the Amazon River, ranged between 0.99 m-1 and 1.99 m-1, and the adet(440) at
the Tapajós and Xingú was 0.21 m-1 and 0.42 m-1, respectively. Mean chl-a concentration at
the Amazon River was 1.77 mg m-3, and at the Tapajós and Xingú rivers was 8.7 and 5.9 mg
m-3 respectively. Preliminary analysis of this data set shows that during the high water season,
the Amazon River is dominated by CDOM and detritus, while the Tapajós and Xingú rivers are
∗
†
Intervenant
55
dominated by chl-a and CDOM. During the low water season, the absorption coefficients are well
mixed
at all the bio,
stations,
a slightly
highsensing,
chl-a at
the Tapajós
Mots-Clés:
opticalwith
properties,
remote
Amazon
river River.
56
Utilisation des images satellite dans la
définition de la stratégie du réseau de
surveillance DCE en Guyane
Luis Lampert
1
∗† 1
, Philippe Bryere , Francis Gohin
IFREMER (IFR) – Ministère chargé de l’enseignement supérieur et de la recherche, Ministère de
l’écologie de l’Energie, du Développement durable et de l’Aménagement du territoire – Ifremer
Dyneco-pélagos Pointe du diable 29280 PLOUZANE, France
Le manque de données marines historiques en Guyane n’a pas permis de définir aisément les
stratégies de la Directive Cadre Européenne (DCE) des eaux côtières marines au niveau de ce
qui a été fait en métropole depuis plus de 10 ans. Avec des échantillonnages tel que prévus dans
les procédures DCE, il faudrait un ou deux plans de gestion de 6 ans pour pouvoir statuer sur la
pertinence des stratégies mises en place ainsi que du découpage de la masse d’eau côtière (MEC).
Une façon de résoudre le problème est de mettre en place une base de données issue des images
satellite, avec des données qui peuvent remonter à plus de dix années. Cette démarche permet
d’acquérir les connaissances de base sur l’évolution des paramètres tels que la température, la
turbidité et la concentration en chlorophylle-a sur le plateau continental guyanais (une centaine
de kilomètres) et sur la MEC, qui s’étend sur 2 à 10 km des côtes selon la présence des îlets.
Pour la création de la base de données, diverses plateformes ont été utilisées. Pour la température
de surface de la mer (SST) nous avons fait appel aux résultats des produits OSTIA, Pathfinder,
ODYSSEA ou GRHSST. Pour les paramètres ” turbidité ” et ” chlorophylle ”, les images des capteurs ” couleur de l’eau ” MODIS et MERIS ont été utilisées avec l’application de l’algorithme
OC5, développé à l’Ifremer et bien adapté aux eaux turbides (Gohin et al. 2002).
L’étude pluriannuelle des données en température, nous renseigne sur l’apparition des années
chaudes (2010) ou froides (2002) par rapport à la moyenne 2002-2012. Une augmentation de la
température moyenne de surface de la mer de 0.8◦C sur 27 années est également constatée. Les
concentrations en chlorophylle sur la MEC, malgré la forte turbidité des eaux côtières, restent
assez élevées grâce au fort ensoleillement, avec des moyennes mensuelles de 1.5 à 7 µg/L. La
turbidité évolue par bancs, qui se déplacent vers le nord-ouest sous l’influence de la dérive littorale générée par l’Amazone. Les turbidités néphélométriques côtières observées avec MODIS
oscillent entre 5 et 40 NTU, exceptionnellement avec des pics de plus de 50 NTU. Cet ensemble
de données reste cohérent avec les analyses des échantillons prélevés par la DCE en 2013.
Les comparaisons réalisées entre les valeurs in-situ et satellite, avec les métriques DCE (Percentile 90), montrent une bonne adéquation des valeurs, sauf quand les échantillons ont été
prélevés dans des points trop particuliers et non représentatifs de toute la masse d’eau. C’est
le cas des points ” Béhague ” et ” Les Hattes ” qui sont dans des endroits où les concentrations
∗
†
Intervenant
57
représentent davantage les conditions d’une vasière ou un estuaire plutôt que celles de la masse
d’eau côtière. Les résultats obtenus permettent d’envisager une bonne représentativité de la couverture de la masse d’eau côtière avec le suivi de 4 points in-situ. Deux points près de Cayenne,
un côtier et un autre au large (île du Connétable par exemple), et deux points à Kourou, avec
un côtier et un autre aux îles du Salut.
Sur la base de ces données, il est proposé une stratégie d’échantillonnage nouvelle, avec des points
de suivi et des fréquences qui s’adaptent au mieux à l’évolution de l’ensemble de la MEC observée
par satellite. Il est également proposé des grilles de niveau DCE, adaptées des eaux métropolitaines,
en turbidité
et chlorophylle
qui répondent
auxturbidité,
caractéristiques
des eaux guyanaises.
Mots-Clés:
télédétection,
DCE, SST,
chlorophylle,
Guyane française
58
Aplicação de tecnologia LIDAR no
monitoramento de áreas costeiras em
diferentes ambientes: costa amazônica e praias
arenosas do Nordeste Brasileiro
Santos André Luis Silva Dos
2
3
∗† 1
, Amaro Venerando Eustáquio
, Valdenira Santos
∗
∗
, Santos Marcelo Soares Teles
∗
4
1
Instituto Federal do Maranhão (IFMA) – Avenida Getúlio Vargas, 04 – 65030-005 – São Luis - MA,
Brésil
2
Universidade Federal do Rio Grande do Norte (UFRN) – Campus Universitário - 59078-970 – Natal RN, Brésil
3
INSTITUTO DE PESQUISAS CIENTÍFICAS E TECNOLÓGICAS DO ESTADO DO AMAPÁ IEPA – Brésil
4
Universidade Federal do Sul da Bahia (UFSB) – Rod. Ilhéus - km 39, BR 415, Ferradas – 45613-204 –
Itabuna - BA„ Brésil
As áreas costeiras amazônicas são palco de intensos processos de sedimentação devido a influência da descarga sedimentar do rio Amazonas e do regime de macromarés. Em contraponto,
no nordeste brasileiro, praias arenosas apresentam altas taxas de erosão, sob o impacto direto de
ondas e correntes litorâneas. Mapear as mudanças morfológicas de curto período nestas áreas é
extremamente difícil devido às dificuldades de levantamentos in situ que possam acompanhar a
velocidade dos processos costeiros. Os métodos convencionais utilizando teodolito, nível, estação
total ou GNSS possuem dificuldade para aplicação quer seja pelos altos custos de campo e tempo
de coleta de dados em intervalo de ciclo de preamar. Ademais, na costa amazônica, o acesso é
muito remoto. Assim, são necessárias ferramentas com alto poder de coleta de dados em curto
espaço de tempo e resolução para detecção das mudanças no espaço e no tempo.
Este trabalho mostra o mapeamento de mudanças morfológicas em uma zona de intermaré, no
estuário do rio Araguari, AP e em uma praia no litoral do nordeste brasileiro, comparando
Modelos Digitais de Elevação (MDE) elaborados a partir do uso do LST em diferentes escalas
temporais: trimestral para as praias arenosas (agosto e novembro/2012 e fevereiro/2013) e anual
para os terraços lamosos na costa amazônica brasileira (setembro/2012, novembro/2013 e setembro/2014). O objetivo principal foi verificar a alteração volumétrica causada pelos processos de
∗
†
Intervenant
59
erosão e deposição a partir de uma análise espacial e temporal.
Os resultados indicaram um balanço sedimentar negativo para os terraços lamosos. Nas praias
arenosas foi observada intensa erosão resultante de fatores meteoceanográficos, pois o período
estudado foi característico de intervalo destrutivo com alta taxa de remoção de sedimentos da
praia e pós-praia. Os resultados indicam que para o mesmo tipo de resposta, diferentes processos
podem estar envolvidos. Na costa amazônica, o balanço negativo indicou consolidação de material, enquanto que para o litoral nordestino, processos de erosão. Estes resultados demonstram
que em cenários de mudanças costeiras, a técnica deve ser utilizada acoplado com outros dados
geológicos
e oceanográficos
regionais.
Mots-Clés:
Laser Escâner
Terrestre, Modelos Digitais de Elevação, Costa Amazônica, Nordeste
Brasileiro.
60
Détection et suivi des bancs de vase littoraux
en Guyane française
Erwan Gensac
1
∗ 1
, Jean-Michcel Martinez 2 , Vincent Vantrepotte 3 , Antoine
Gardel 4
Géosciences Marines et Géologie du Littoral (GMGL) – UMR CNRS 6538 LDO-GMGL – France
2
Géosciences Environnement Toulouse (GET) – UMR 5563 (CNRS – France
3
Laboratoire d’Océanologie et de Géosciences (LOG) – INSU-CNRS, UMR 8187 – France
4
Laboratoire d’Océanologie et de Géoscience (LOG) – INSU-CNRS, UMR 8187 – France
L’influence de l’Amazone se ressent jusqu’à l’Orénoque, 1500 km au nord-ouest de son embouchure. Ce littoral sous influence amazonienne, nommé côte des Guyanes, est un espace
extrêmement instable régit par la migration de vastes bancs de vase subtidaux en provenance de
l’Amazone. Ces bancs de vase se forment dans la région des Caps à la frontière franco-brésilienne
et migrent sous l’effet combiné des houles et des courants à une vitesse de 1 à 2 km.an-1. Au
cours de leur migration ces bancs de vase favorisent la progradation de la côte vers le large par
le développement de vasières intertidales rapidement colonisées par la mangrove côtière. Leur
absence favorise quant à elle l’érosion rapide du littoral. Des reculs du trait de côte pouvant
atteindre plusieurs centaines de mètres par an, pour les secteurs à mangrove, ont été mesurés.
Le littoral guyanais, même s’il est pratiquement vierge de toute empreinte humaine, concentre
la majorité des populations et des activités économiques. Les problématiques d’envasement portuaire, d’érosion des habitations et des zones agricoles, l’évolution des surfaces de mangroves
mais aussi des écosystèmes côtiers, sont étroitement liées à la migration des bancs de vase. Ces
problématiques déjà complexes seront exacerbées dans les années à venir par les répercussions du
changement climatique global. Accroître les connaissances sur la morphodynamique des bancs
de vase, dans une vision prédictive, est ainsi un enjeu urgent vis-à-vis du contexte actuellement
contradictoire entre, d’un côté l’augmentation de la pression anthropique sur les zones côtières
et de l’autre côté la montée du niveau marin.
Les travaux de recherche qui seront présentés traiteront des différentes techniques de détection
des bancs de vase en Guyane française développées au cours de ces dernières années. La méthode
reposant sur l’estimation par satellite des matières en suspension (MES) sera plus particulièrement développée. Grâce à cette méthode d’analyse il a été possible d’identifier les bancs de vase
et de suivre leur migration depuis février 2000 au pas de temps mensuel. La zone d’étude ne
se concentre pas uniquement à la Guyane française mais s’étend sur tout le littoral sous influence amazonienne. Jusqu’à présent les études se sont focalisées en Guyane, cependant il semble
essentiel de ne plus se limiter à des frontières administratives mais de considérer le système de
migration des bancs de vase dans sa globalité. Cette vision d’ensemble, de par la multiplication
des bancs de vase suivis, améliore la compréhension de l’influence des forçages hydro-climatiques
et des activités anthropiques sur leur vitesse de migration et leur impact sur la côte (développement de mangrove / érosion). Entre février 2000 et décembre 2014, vingt-neuf bancs de vase
ont été identifié le long du littoral sous influence amazonienne, migrant à des vitesses variant
∗
Intervenant
61
entre 1 km.an-1 et 5,8 km.an-1. Les causes multifactorielles de ces différences de vitesse de migration et leurs influences sur l’évolution littorale seront discutées. Ces résultats améliorent la
compréhension globale du système de migration des bancs de base et permettent d’insérer les
processus géomorphologiques locaux dans un contexte général. Ces travaux constituent une base
de données inédites qui servira de base pour toutes les études en lien avec les problématiques
d’envasements et d’érosion mais aussi pour décrypter l’impact du changement du niveau marin
et des
régimes océano-climatiques
survase,
la migration
bancs de vase.
Mots-Clés:
télédétection, banc de
migration des
sédimentaire
62
Structure-from-Motion photogrammetry for
high-resolution coastal geomorphic surveys
Guillaume Brunier ∗† 1 , Jules Fleury 1 , Edward Anthony 1 , Philippe
Dussouillez 1 , Antoine Gardel 2
1
Centre européen de recherche et d’enseignement de géosciences de l’environnement (CEREGE) – Aix
Marseille Université, INSU, Institut de recherche pour le développement [IRD], CNRS : UMR7330 –
Europôle Méditerranéen de l’Arbois - Avenue Louis Philibert - BP 80 - 13545 Aix-en-Provence cedex 4,
France
2
UMR CNRS 8187 LOG en délégation au CNRS Guyane – CNRS : USR3456 – Immeuble le relai. 2
av. G. Charlery. 97300 Cayenne, France
Photogrammetry is an old remote sensing technique that has undergone significant new developments related to the emergence of new computer-based applications, notably the workflow
technique called Structure-from-Motion (SfM photogrammetry). These innovations facilitate
the utilization of this technique by non-specialists. SfM photogrammetry now enables the production of high-resolution morphometric models and derived products such as digital surface
models (DSMs) and orthophotographs. We conducted three photogrammetric experiments on
the embayed beach of Montjoly in Cayenne during the last phase of rotation, in 2013/2014, that
periodically affects this beach under the influence of mud banks migrating alongshore, and on a
small mudflat sector of a coastal mud bank near the Sinnamary estuary, both in French Guiana.
We developed a simple field protocol based on sub-vertical aerial photography from a microlight
aircraft flying at low altitude (1000 feet). We generated DSMs and other products, including
c software. These SfM implementations
orthophotos, with user-friendly Agisoft Photoscan ()
were aimed at highlighting the subtle morphological variations characterising the beach, such
as erosion scarps, and incipient aeolian dunes and engineering structures, and drainage channels
and ravinement features on the mud flat. We monitored some of the processes involved in morphological change, including beach rotation. The DSMs were produced at a resolution of 5 to
10 cm per pixel and had a mean vertical accuracy less than 10 cm compared to the Real-Time
Kinematic Differential Global Positioning System (RTK-DGPS) control points, with a maximum
of 20 cm in marginal sectors near vegetation and on wet surfaces in the intertidal zone. Low-cost,
user-friendly SfM photogrammetry offers interesting new perspectives in coastal geomorphology
studies requiring high-resolution topographic data. The technique combines the advantages of
the reproducibility of GPS topographic surveys and the high density and accuracy of airborne
LIDAR,
but at very
advantageous cost
compared
the latter.
Mots-Clés:
SfM photogrammetry,
high
resolutiontoDSM,
morphometry, beach, mudflat
∗
†
Intervenant
63
Recent Pelagic Sargassum Blooms in Atlantic
Equatorial Regions
James Franks
1
∗† 1
University of Southern Mississipi – Gulf Coast Research Laboratory Center for Fisheries Research and
Development, Ocean Springs, États-Unis
Since 2011, unprecedented quantities of pelagic sargassum, a complex of two co-occurring
species of floating marine macroalgae (Sargassum natans, Sargassum fluitans; Class Phaeophyceae), have washed ashore on Western Central Atlantic countries, extending from Brazil
to eastern and western Caribbean nations. Back-tracking of sargassum movement (drift) using ocean circulation models revealed the origin of the sargassum influx was equatorial rather
than the Sargasso Sea. Several north Atlantic climate indices with decadal-scale oscillations
reached historical maxima/minima during 2010-2011. A hypothesis is developed using ocean
models together with satellite-tracked ocean drifters to suggest that climate related circulation
changes in the equatorial Atlantic created conditions for increased pelagic sargassum retention
and consolidation, while warm, nutrient-rich conditions fueled by Amazon River outflow, equatorial upwelling, and African atmospheric dust aided its growth and proliferation. The sheer
quantity of sargassum in the invasive events and the frequency of events are compromising living
marine resources and habitats, economies, and community life in affected coastal regions. The
consequences for marine ecosystems are presently unknown. A fundamental understanding of
the dynamics of recent sargassum blooms and coastal incursions is required in order to facilitate development of sargassum event prediction capabilities and response strategies by tropical
Atlantic
nations.Pelagic sargassum blooms, Atlantic equatorial regions
Mots-Clés:
∗
†
Intervenant
64
Liste des auteurs
Aller, Robert, 13, 21, 24
Almeida, Paula, 11
Alt, Arthur, 21
AMANAJÁS, Viviane, 31
André Luis Silva dos, Santos, 56
ANTHONY, Edward, 60
anthony, edward, 13
Artigas, Luis Felipe, 19
Aschenbroich, Adélaïde, 21
Baulier, Loïc, 10
Bihannic, Isabelle, 21
Blanchard, Fabian, 10, 40
Blevin, Pierre, 45
Bourbon, Pierre, 32
brunier, guillaume, 60
BRYERE, PHILIPPE, 54
Bustamante, Paco, 45
Bynoe, Paulette, 38
Cabral, Marcelo, 29
Caillaud, Jacinthe, 19
Carvalho, Gabriel, 29
Cassou, Christophe, 13
Chambault, Philippine, 47
Chastel, Olivier, 45
Chaves, Filipe, 11
Chevalier, Johan, 34
CHEVALLIER, Damien, 47
Chow-Toun, Franck, 7
Cissé, Abdoul, 40
Costantini, David, 45
Covaci, Adrian, 45
Cruz, Leonardo, 29
da Silva, João Paulo, 4
Dall Cortivo, Fabio, 3
DE LA TORRE, Ywenn, 32
de Thoisy, Benoît, 45
Denis, Lionel, 19
Diop, Bassirou, 50
Doyen, Luc, 40, 48
Duke, Norman, 25
Duong, Gwendoline, 19
Dussouillez, Philippe, 60
Eens, Marcel, 45
Estevam, Marciel, 11
Estrada, Gustavo, 11, 15, 29
Eulaers, Igor, 45
Fernandez, Viviane, 11
Fleury, Jules, 60
Fragoso, Maurício, 29
Franks, James, 61
FRAZÃO, Maísa, 31
Freitas, Lucas, 3
Fromard, François, 13, 21
Fung A Loi, Christa, 23
Gaines, Steven, 23
Gardel, Antoine, 5, 13, 21, 58, 60
Gensac, Erwan, 58
Gilbert, Franck, 21
GOHIN, Francis, 54
Gomez, Fernando, 19
Gommeaux, Maxime, 19
Gontharet, Swanne, 19
Govindan, Malarvannan, 45
Huybrechts, Nicolas, 5
Kampel, Milton, 3, 52
Kandaswamy, Suresh, 17
Krusche, Alex, 52
Lévêque, Jean, 19
LAMPERT, LUIS, 54
le Garrec, Vincent, 21
Le Maho, Yvon, 47
Lesourd, Sandric, 5, 19
Magraoui, Amira, 10
Marcelo Soares Teles, Santos, 56
Martinez, Jean-Michcel, 58
Martinez, Jean-Michel, 13
Mathieu, Olivier, 19
Michaud, Emma, 21
Milloux, Marie-Jeanne, 19
Moisan, Manuel, 32
Monnier, Olivier, 7
Naipal, Sieuwnath, 23
Negrel, Philippe, 8
Orseau, Sylvain, 5
Palisse, Marianne, 36
65
Pellegrini, Júlio, 29
pereau, jean-christophe, 51
PEREIRA, Ricardo, 31
Petelet-Giraud, Emmanuelle, 8
Prado-Merini, Oscar, 40
Proisy, Christophe, 13
Rey, Stéphanie, 7
Richey, Jeffrey, 52
Rousseau, Yann, 43
Rudorff, Natalia, 3
Santos [et al], Valdenira, 27
Santos, Francisco, 29
Santos, João Felipe, 3
SANTOS, VALDENIRA, 56
Santos, Valdenira, 4
Sarrazin, Max, 19
Sebastiano, Manrico, 45
Soares, Felipe, 29
Soares, Mário, 15
Soares, Mario, 11, 29
Stieglitz, Thomas, 21
Tavares, Marcos, 21
Thouzeau, Gérard, 21
Valerio, Aline, 3, 52
Vantrepotte, Vincent, 58
Venerando Eustáquio, Amaro, 56
Villanueva, Maria Ching, 42
Walcker, Romain, 13
Yussuff, Tana, 17
Zoffoli, Maria, 3
66
67

Untitled - CNRS Guyane

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