UNDERSTANDING DRASTIC CHANGES IN ZOOPLANKTON AND MEDUSAE COMMUNITIES OVER THE 2003-2011 PERIOD IN THE MEDITERRANEAN SEA (CORSICA)

in 2012 ASLO aquatic sciences meeting : Voyages of discovery (2012, July)

Impact des mouillages forains sur la qualité de l’eau et du phytoplancton : résultats d’une étude préliminaire menée en Baie de Calvi (Corse)

Conference (2012, May 16)

Le plus souvent, l’étude de l’impact des mouillages forains sur l’environnement aquatique concerne l’analyse des dégradations subies par la faune et la flore benthiques. Cependant, dans nos régions, la ... [more ▼]

Le plus souvent, l’étude de l’impact des mouillages forains sur l’environnement aquatique concerne l’analyse des dégradations subies par la faune et la flore benthiques. Cependant, dans nos régions, la grande majorité des bateaux de plaisance construits avant 2008 et de longueur inférieure à 24 mètres ne sont pas équipés d'installations de stockage des eaux résiduaires (eaux ménagères, douches, eaux noires des toilettes) et encore moins de traitement à bord des effluents. Une partie des eaux usées de la plaisance est donc rejetée en mer sans que leur charge polluante et leur impact sur les eaux de surface ne soient connus. De mai à septembre 2011, une étude pilote a été menée dans une zone de mouillage forain de taille moyenne de la Baie de Calvi (site de l’Alga) dans le double but d’analyser la qualité du phytoplancton (biomasse et composition) et la charge en Escherichia coli des eaux de surface. Les données obtenues à l’Alga sont comparées à celles du point de référence DCE pour l’étude du phytoplancton, situé à proximité de STARESO. Les résultats obtenus à l’Alga mettent en évidence les éléments suivants : 1. Biomasse phytoplanctonique totale : la biomasse phytoplanctonique totale de l’Alga est proche de celle mesurée à la station de référence; 2. Composition phytoplanctonique : alors que la composition du phytoplancton du site de référence est constante au cours de la saison estivale, le phytoplancton de l’Alga se caractérise par une augmentation progressive de la concentration en Cyanobactéries, un groupe dont la croissance est favorisée par la présence d’ammonium; 3. Charge en E. coli : des concentrations de 100 à 300 E. coli par 100 ml d’eau sont mesurées de juillet à septembre dans tous les échantillons de surface de la zone de mouillage alors qu’elles sont toujours absentes de la station de référence. Les apports diffus liés aux rejets des eaux usées de la plaisance paraissent donc suffisants pour affecter la composition du phytoplancton et la charge bactérienne des eaux de surface d’une zone de mouillage forain de taille moyenne. Les implications en termes d’impact sur la qualité de l’eau et de l’écosystème seront discutées. Depuis mars 2012, un suivi complet de l’influence de la zone de mouillage forain de l’Alga sur l’écosystème côtier est réalisé dans le cadre du projet STARECAPMED. [less ▲]

Neustonic microplastic and zooplankton in the North Western Mediterranean Sea

in Marine Pollution Bulletin (2012), 64

Neustonic microplastic and zooplankton abundance was determined in the North Western Mediterranean Sea during a summer cruise between July 9th and August 6th 2010, with a break between July 22th and 25th ... [more ▼]

Neustonic microplastic and zooplankton abundance was determined in the North Western Mediterranean Sea during a summer cruise between July 9th and August 6th 2010, with a break between July 22th and 25th due to a strong wind event. Ninety percent of the 40 stations contained microplastic particles (size 0.3-5 mm) of various compositions: e.g., filaments, polystyrene, thin plastic films. An average concentration of 0.116 particles/m² was observed. The highest abundances (> 0.36 particles/m²) were observed in the shelf stations. The neustonic plastic particles concentrations were 5 times higher before than after the strong wind event which increased the mixing and the vertical repartition of plastic particles in the upper layers of the water column. The values rise in the same order of magnitude than in the North Pacific Gyre. The average ratio between microplastics and mesozooplankton weights was 0.5 for the whole survey and might induce a potential confusion for zooplankton feeders. [less ▲]

Response of plankton communities of the Bay of Calvi (northwestern Mediterranean) to climate variation over the past three decades

in Symposium "Vulnerability of coastal ecosystems to global change and extreme events", Biarritz, France, 18-21 October 2011 (2011, October)

Long-term changes of surface plankton dynamics are studied from three decades at a permanent station in the oligotrophic Bay of Calvi (Corsica, northwestern Mediterranean) where water quality is unbiased ... [more ▼]

Long-term changes of surface plankton dynamics are studied from three decades at a permanent station in the oligotrophic Bay of Calvi (Corsica, northwestern Mediterranean) where water quality is unbiased by terrestrial inputs. As a distinctive feature of the Bay, a plurimodal plankton bloom occurs generally between January and April, with very large interannual variability reaching one order of magnitude from one year to another. Later in the season, the plankton biomass remains very low from May to December. Contrarily to the 1979 - 1998 period where a continuous decrease of phyto- and zooplankton biomasses was observed, observations from the last decade (1999 - 2011) emphasize abrupt changes in plankton biomass and bloom duration from one year to another in response to succession of mild and rigorous winters. Studies conducted to understand mechanisms controlling plankton variability emphasize a close relationship between winter wind stress intensity, water temperature, nutrient inputs and phytoplankton biomass. Total phytoplankton biomass is maximum during years characterized by high winter wind stress and low winter water temperature. From a specific point of view, flagellates are always the dominant component of the winter - spring phytoplankton communities. However, diatoms tend to be more abundant during rigorous winter years. Shifts in phytoplankton community structure contribute to control the dynamics of zooplankton that rely on phytoplankton as food and influence the temporal succession of zooplankton assemblages. Time-series results indicate the high sensitivity of the plankton ecosystem to climate change and confirm that the Bay of Calvi reacts rapidly to external perturbations, which are driven by climate variation. [less ▲]

Utilisation de la signature pigmentaire du phytoplancton pour la mise au point d’un indice de composition

Scientific conference (2011, April)

Sur base de la sensibilité du phytoplancton aux apports anthropiques de sels nutritifs, la DCE a retenu un indicateur « Phytoplancton » pour contribuer à caractériser l’état écologique des masses d’eau ... [more ▼]

Sur base de la sensibilité du phytoplancton aux apports anthropiques de sels nutritifs, la DCE a retenu un indicateur « Phytoplancton » pour contribuer à caractériser l’état écologique des masses d’eau. Il est composé de trois indices : la biomasse, l’abondance et la composition. La biomasse et l’abondance sont caractérisées par des métriques qui sont déjà validées ou en cours de l’être au niveau européen. Cette étude cible la composition du phytoplancton et utilise la signature pigmentaire des communautés pour développer un nouvel indice de composition taxonomique (IC Medit). L’indice IC Medit est adapté aux spécificités des eaux côtières méditerranéennes et aux besoins de la DCE. Il 1) caractérise l’évolution naturelle de la distribution saisonnière de 2 grands ensembles phytoplanctonique-clés; 2) incorpore la variabilité interannuelle des communautés; 3) reflète l’évolution de la qualité des masses d’eau; 4) permet d’émettre des hypothèses sur le type de pressions qui modifient la composition phytoplanctonique. [less ▲]

Interannual variability of zooplankton in the Dumont d’Urville sea (139°E – 146°E), east Antarctica, 2004 - 2008

in Polar Science (2011), 5

Spatial and temporal variability of zooplankton was studied during five summers (2004 - 2008) in the Dumont d’Urville Sea, east Antarctica. The species recorded, based on the catch of a 500 um-mesh Bongo ... [more ▼]

Spatial and temporal variability of zooplankton was studied during five summers (2004 - 2008) in the Dumont d’Urville Sea, east Antarctica. The species recorded, based on the catch of a 500 um-mesh Bongo net, were typical of southern continental shelf communities in Antarctica, including Euphausia crystallorophias, polychaetes, pteropods and biomass-dominant copepods. There was a strong degree of temporal variation in abundance, possibly related to the thickness and extent of the sea ice cover during each spring prior to the surveys. Total mean abundance was highly variable between years, with a minimum of 961 ind. 1000 m-3 in 2004 (range 65 - 3407 ind. 1000 m-3) and a maximum of 15627 ind. 1000 m-3 in 2005 (range 5109 - 33869 ind. 1000 m-3). Spatially, within each year, abundances were also variable, and there were no uniform patterns in abundance from year to year. Water column physical characteristics (temperature and salinity) were relatively constant and did not contribute substantially to variation between the years. It is likely that variation in zooplankton distribution was largely related to a combination of localised features, such as the thickness and extent of sea ice cover, the position and extent of the Mertz Polynya, local wind conditions and bathymetric features. [less ▲]

Importance of copepod carcasses versus faecal pellets in the upper water column of an oligotrophic area

in Estuarine Coastal & Shelf Science (2011), 92

Downward flux of zooplankton faecal pellets and carcasses was studied during and after the spring bloom in an oligotrophic coastal area of the Western Mediterranean using a « swimmer-excluding » sediment ... [more ▼]

Downward flux of zooplankton faecal pellets and carcasses was studied during and after the spring bloom in an oligotrophic coastal area of the Western Mediterranean using a « swimmer-excluding » sediment trap. Zooplankton detritus retrieved in the trap were comprised of cylindrical faecal pellets (from meso- and macrozooplankton) and copepod carcasses with a respective carbon flux of 0.05 - 2.69 mg m-2 d-1 and 0.42 - 4.37 mg m-2 d-1. Carbon and nitrogen flux of carcasses always exceeded that of faecal pellets, except at the beginning of the bloom due to a higher contribution of macrozooplankton faecal material. During the peak of phytoplankton biomass, total faecal flux essentially comprised of copepod faecal pellets (68 - 86% of the total faecal carbon), whereas before and after this period, macrozooplankton faecal material dominated (88 - 91% of total faecal carbon flux). Copepod faecal flux was positively correlated with phytoplankton biomass. Estimates of non-predatory biomass mortality rates (from < 0.01 to 0.05 d-1) were negatively correlated with chl a with a time lag of 12 days and were lower than predatory mortality values reported in the same area. The paper discusses the relative importance of carcasses versus faecal pellet flux and of non-predatory versus predatory mortality, as well as the potential role of these zooplankton detritus in supporting the production of benthos in oligotrophic areas. [less ▲]

Multiparametric observations and analysis in the Bay of Calvi (Corsica), an ideal site for studying the human activity effects and climate changes in the Mediterranean Sea; STARESO

Conference (2010, May)

STARESO (Station de REcherche Sous marine et Océanographique) is the marine and oceanographic research station of the University of Liège (Belgium) managed by the French company STARESO S.A.. Constructed ... [more ▼]

STARESO (Station de REcherche Sous marine et Océanographique) is the marine and oceanographic research station of the University of Liège (Belgium) managed by the French company STARESO S.A.. Constructed in 1969, it is located near Calvi (Corsica, Western Mediterranean Sea) in an oligotrophic area chosen for the exceptional quality of its coastal waters STARESO offers to the oceanographers, by diving or with boats, a direct access to the sea. The variety of the accessible ecosystems is remarkable and unique in the Mediterranean basin: -the Bay of Calvi is characterized by healthy and very diverse biocenosis (e.g. Posidonia meadows, rocky and sandy communities, -a steep submarine canyon, with depths greater than 1 000 meters, is accessible in 15 minutes of navigation; -the Liguro-Provençal front, a major hydrologic structure, is situated between 10 and 15 miles of the coast. STARESO is accessible all the year for everybody and is functioning like an oceanographic research vessel. The Station is a platform for all oceanographic disciplines with a scientific expertise widely based on a long tradition of interdisciplinary work, and a direct access to time series of physical, chemical and biological data registered with automated systems and variety of sensors deployed in the Bay of Calvi since 30 years. This platform provides the opportunity to reach coastal, pelagic, benthic, deep systems with a manageable cost and ship requirements in a pristine zone. [less ▲]

Spatial variability of the Siphonophora along the radial Calvi-Nice (Corsican side)

Poster (2010)

The spatial distribution of the Siphonophorae has been examined, in Occidental Mediterranean, along the radial Calvi-Nice, from Calvi up to 30 miles offshore in September 2009. The variation of the ... [more ▼]

The spatial distribution of the Siphonophorae has been examined, in Occidental Mediterranean, along the radial Calvi-Nice, from Calvi up to 30 miles offshore in September 2009. The variation of the abundance of the plankton and of the Siphonophorae was put in relation with the hydrological structures of the Liguro-Provençal front. This structure separates the coastal waters of Atlantic origin from the offshore central Mediterranean waters of deep origin. Globally, the larger abundances of Siphonophorae were present in inshore waters between the front and the coast. Both nectophores (asexual stage) and gonophores and bracts (reproductive stage) of Lensia subtilis occured only in the inshore waters. The nectophores of Chelophyes appendiculata occured at all sampling stations with no significative variation. However, the abundance of the bracts and the gonophores increases when we get closer to the coast. This allows us to hypothesize that the maximum of reproduction is located in waters close to the coast. On the other hand, the larvae abundance of calycophoran siphonophores, in the plankton samples, increase from the coastal waters to the offshore waters with a maximum of abundance at the station located at 25 miles offshore. That contradiction could be explained by plankton net avoidance of small larvae, by current transport or by variable hatching success at the various stations. The larvae of physonect siphonophores are more often found offshore. [less ▲]

Problematic of the Pelagia noctiluca outbreaks in the Bay of Calvi (Corsica)

in Proceedings of the 39th CIESM Congress (2010)

The interannual variations of the Schyphozoan jellyfish Pelagia noctiluca is estimated by weekly measurements in the Bay of Calvi (Corsica) from 2003. The mean annual abundance reaches a dramatic maximum ... [more ▼]

The interannual variations of the Schyphozoan jellyfish Pelagia noctiluca is estimated by weekly measurements in the Bay of Calvi (Corsica) from 2003. The mean annual abundance reaches a dramatic maximum in 2006. The medusae appear by migration of active swarms on the shelf and at the external limit of the Bay. Degraded individuals drift as passive swarms, throughout inner side of the Bay and embayments. [less ▲]