The nutritional quality of non-calcified macroalgae in Guadeloupe (Lesser Antilles) evaluated by their biochemical composition

Biochemical compositions of 15 species and 1 genus of macroalgae were studied. Concentrations of macronutrients were measured to evaluate their nutritional quality. High concentrations of proteins, lipids and soluble carbohydrates generally indicate a high nutritional quality because these compounds are readily metabolically available for consumers and provide a large proportion of energy. Insoluble carbohydrates are more difficult to digest and high concentrations indicate a low nutritional quality. Three groups of macroalgae were identified according to their biochemical characteristics. The first group clusters Ceramium cf nitens, Ulva cf lactuca and Lobophora cf variegata due to their high concentrations of proteins and soluble carbohydrates, and low proportion of ashes. These species presented high nutritional qualities and, according to previous studies, are preferredby herbivorous fishes. A second group constituted by Dictyota cf pulchella, Caulerpa cupressoides, C. sertularioides and Sargassum cf polyceratium presented intermediate nutritional qualities due to higher concentrations of lipids and insoluble carbohydrates. Finally, the others species and genus are characterized by a high proportion of ashes and a low nutritional quality. However, some of these species (Acanthophora spicifera, Padina cf sanctae-crucis or Laurencia cf chondrioides) are cited as preferred macroalgae for some herbivorous fishes. The present study indicates that the biochemical composition in macronutrients only partially explains the food choice made by fishes. The consumption of macroalgae by herbivores depends also on the presence of deterrent molecules, the composition in micronutrients, and their palatability that often decreased with increasing size. Most of macroalgae are preferentially consumed when young and small

L'ichtyofaune des herbiers de phanérogames marines des Antilles françaises : intérêt de leur protection

The fish communities of the seagrass beds of Thalassia testudinum were studied in the bay of Fort-de-France (Martinique) and the lagoon of the Grand Cul-de-sac Marin (Guadeloupe) over a period of two years. Fishes were collected using a seine net in two stations in Martinique and three stations in Guadeloupe. These stations were located near the coastal mangroves and seawards. An overall total of 88 species of fishes was collected in both islands, respectively 64 species in Martinique and 77 species in Guadeloupe. Furthermore, fish abundance was found to be greater in Guadeloupe than in Martinique (2.6 times for number of individuals and about 1.7 for biomass). Correspondence and cluster analyses revealed a different fish community structure in the two types of seagrass beds in both islands: one assemblage is settled near mangroves and another one in the seaward seagrass beds. In number of species, fish abundance and biomass, the fish community was richer near the coast than seawards. In the two types of seagrass fish community, juveniles characterized the majority of the species, including those of commercial interest. These latter represent an important part of the community with higher proportions near mangrove areas (75.5 % in numbers and 69.3 % in biomass) than seawards (41.6 % in numbers and 43.3 % in biomass). These results confirm the role of nursery played by Thalassia testudinum beds in the West Indies and show the necessity to protect that habitat for a sustainable management of resources for coastal fisheriesLes communautés de poissons des herbiers de Phanérogames marines à Thalassia testudinum ont été étudiées simultanément dans deux stations de la baie de Fort-de-France en Martinique et trois stations situées dans la réserve du Grand Cul-de-sac Marin en Guadeloupe. Un total de 88 espèces a été observé dans les deux îles, avec respectivement 64 espèces en Martinique et 77 espèces en Guadeloupe. L'abondance globale des poissons s'est révélée être plus élevée dans les zones de réserve en Guadeloupe qu'en Martinique (2,6 fois en effectifs et 1,7 fois en biomasse). Des analyses factorielles des correspondances ainsi que des classifications hiérarchiques ont permis de mettre en évidence l'existence de deux types de communautés : une communauté installée en bordure de mangrove et une autre présente dans les herbiers situés plus au large. La première communauté est plus riche en espèces, en effectifs et en biomasse. Dans ces deux types d'herbiers, la majorité des espèces est représentée par des poissons juvéniles, espèces d'intérêt commercial comprises. Ces dernières représentent une proportion importante de l'ichtyofaune, plus élevée en bordure de mangrove (75,5 % des effectifs et 69,3 % de la biomasse) qu'au large (41,6 % des effectifs et 43,3 % de la biomasse). Ces résultats confirment le rôle de nurserie joué par les herbiers de Thalassia testudinum dans les Antilles et montrent la nécessité de protéger cet habitat dans le cadre d'une gestion durable des ressources pour la pêche côtière

Trophic relationships in a tropical stream food web assessed by stable isotope analysis

1. Stable isotope analysis, coupled with dietary data from the literature, was used to investigate trophic patterns of freshwater fauna in a tropical stream food web (Guadeloupe, French West Indies). 2. Primary producers (biofilm, algae and plant detritus of terrestrial origin) showed distinct delta C-13 signatures, which allowed for a powerful discrimination of carbon sources. Both autochthonous (C-13-enriched signatures) and allochthonous (C-13-depleted signatures) resources enter the food web. The migrating behaviour of fishes and shrimps between marine and freshwater during their life cycles can be followed by carbon isotopes. Here, shrimp delta C-13 signatures were shown to shift from -16 parts per thousand (for juveniles under marine influence) to -24.7 parts per thousand (for adults in freshwater habitats). For resident species, delta C-13 values partly reflected the species' habitat preferences along the river continuum: species living in river mouths were C-13-enriched in comparison with those collected upstream. 3. Nitrogen isotopic ratios were also discriminating and defined three main trophic guilds among consumers. The delta N-15 values of herbivores/detritivores were 5.0-8.4 parts per thousand, omnivores 8.8-10.2 parts per thousand and carnivores 11-12.7 parts per thousand. 4. Mixing model equations were employed to calculate the possible range of contribution made by respective food sources to the diet of each species. The results revealed the importance of omnivorous species and the dependence of riverine biota on terrestrial subsidies, such as leaf detritus and fruits. Finally, the abundance of shrimps and their feeding habits placed in relief their key role in tropical freshwater food webs. Isotopic analysis provides a useful tool for assessing animal feeding patterns

Dynamics of the Benthic Communities of Pigeon Islets (Guadeloupe Island, Lesser Antilles) from 2012 to 2021 Monitored by a Photo-Quadrats Technique

Since 2012, the benthic communities of the Pigeon Islets (Guadeloupe Island, Lesser Antilles) have been monitored biannually by the National Park of Guadeloupe using photo—quadrats. This monitoring was carried out at 12 coral reef stations distributed around the islets. The data collected from 2012 to 2021 highlight the significant events that disrupted the coral communities of Guadeloupe. Among these remarkable phenomena, an episode of coral bleaching occurred in 2019, followed by the appearance of a new coral disease, Stony Coral Tissue Loss Disease (SCTLD), in 2020. As a result of these threats, a drop of 54% of coral cover was observed in the monitored sites, accompanied by a rise of 16% of the surface occupied by macroalgae. The protocol set up by the National Park of Guadeloupe was found to be efficient to follow the temporal dynamics of benthic reef communities

Detection of Adsorbed Chlordecone on Microplastics in Marine Sediments in Guadeloupe: A Preliminary Study

Plastic pollution in the oceans is recognized as a worldwide problem. Since the 1950s, the production of plastics has been increasing and the first reports of microplastics (particles \u3c 500 μm) in the marine environment began to appear in the 1970s. These particles represent a growing environmental problem due to their dispersion in seawater and marine organisms. Additionally, microparticles in general can adsorb pollutants that will then become bioavailable to organisms by being desorbed during digestion, which could be an important pathway for the contamination of organisms. In Guadeloupe and Martinique, an organochlorine pesticide called “chlordecone” was used from 1972 to 1993 in banana plantations and this very persistent pollutant contaminates soils, rivers, and coastal marine areas and accumulates in marine foodwebs. To examine these issues, we had two goals: 1) to assess the contamination of marine sediments by microplastics surrounding Guadeloupe; and 2) to determine the ability of microplastics to adsorb chlordecone, as has been demonstrated for other organochlorine pollutants. To do so, marine sediments were collected in triplicate from 12 sites in coral reef environments around the island. Microplastics from each sample were then enumerated by size, color and shape under a binocular microscope. The results indicate that microplastics are found in all the studied sites and that their distribution could be linked to marine currents or proximity to areas of significant human activities (port activities, agglomeration, etc.). Finally, our preliminary results indicated that chlordecone could be adsorbed onto microplastics, with a concentration ranging from 0.00036—0.00173 µg/µg of microfilter

Recent evolution of the coral reefs of Guadeloupe and Saint-Barthelemy Islands

The Guadeloupe Archipelago (with Guadeloupe, La Désirade, Marie-Galante, Les Saintes and Petite-Terre Islands), St. Barthélemy and St. Martin are located in the Lesser Antilles between 15°50’and 18°00’ N. Guadeloupe possesses a barrier reef on its northern part, fringing reefs on the windward coast and highly diversified non-reef building coral communities on the leeward coast. The other islands shelter fringing reefs and non-reef building coral communities. The coral reefs of the French West Indies are faced with a common set of threats : high rate of sedimentation, due to deforestation and bad land management, and algal proliferation due to an overload of nutrients in the coastal waters coming from excessive use of fertilizers and poor waste waters treatment. Their coral communities have exhibited a low progressive decline since the beginning of the eighties. Long-term monitoring sites have been implemented in Guadeloupe and St. Barthélemy since 2001. Results indicated the existence of a signifi cant tendency of the coral community to degrade over the study period. Moreover, a severe bleaching event appeared in 2005, when the sea temperature overshoot 29°C from mid May to mid November, with maximum values reaching 31°C. In 2006, in spite of normal seawater temperature conditions, an important delayed mortality affected the corals previously weakened by bleaching. As a final result of the 2005 bleaching event, coral coverage on the reefs of Guadeloupe and St. Barthélemy dropped from 30 to 50 % according to the sites. Fish communities did not exhibit immediate impact of the bleaching eventL'Archipel guadeloupéen (les îles de la Guadeloupe, la Désirade, Marie-Galante, les Saintes et Petite-Terre), ainsi que Saint-Barthélemy et Saint-Martin sont situés dans les Petites Antilles entre 15° 50'N et 18°00' N. La Guadeloupe abrite un récif barrière sur sa côte nord, des récifs frangeants sur les côtes au vent et des formations coralliennes non-bioconstructrices, riches et diversifiées, sur les côtes sous-le-vent. Les autres îles possèdent des récifs frangeants et des formations coralliennes non-bioconstructrices. Les récifs coralliens des Antilles françaises subissent principalement deux types de perturbation: 1) une hypersédimentation liée à la déforestation des îles et à des aménagements côtiers mal réfléchis ; 2) un enrichissement excessif des eaux côtières en nutriments, provenant d'un mauvais traitement des eaux usées et de fertilisants agricoles, qui favorisent le développement exubérant d'algues sur les récifs. Les récifs de ces îles ont montré des signes de dégradation depuis le début des années 80. Depuis 2001, un réseau de stations de suivi de l'état de santé des communautés récifales a été mis en place sur des récifs de Guadeloupe et de Saint-Barthélemy. Les résultats de cette étude mettent en évidence une tendance significative décroissante de l'état de santé des communautés coralliennes. Par ailleurs, en 2005, la température des eaux côtières dans les Antilles a dépassé 29°C de la mimai à la mi-novembre, avec des maxima atteignant 31 °C. Cet événement a provoqué le phénomène de blanchissement des coraux le plus important observé à ce jour dans ces îles. Apparue dès octobre 2005, la mortalité des coraux s'est particulièrement développée en 2006, où elle a constitué, malgré des conditions de température normales, un phénomène retardé. Cet épisode de blanchissement s'est traduit par une diminution de 30 à 50 % du taux de recouvrement des fonds par les coraux en fonction des récifs. Les peuplements de poissons récifaux n'ont pas été affectés de façon immédiate par le blanchissement

Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

BACKGROUND The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.This work was partially supported by salaries from the NOAA Coral Reef Conservation Program to the NOAA Coral Reef Conservation Program authors. NOAA provided funding to Caribbean ReefCheck investigators to undertake surveys of bleaching and mortality. Otherwise, no funding from outside authors' institutions was necessary for the undertaking of this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Siglec-H is a microglia-specific marker that discriminates microglia from CNS-associated macrophages and CNS-infiltrating monocytes

International audienceSeveral types of myeloid cell are resident in the CNS. In the steady state, microglia are present in the CNS parenchyma, whereas macrophages reside in boundary regions of the CNS, such as perivascular spaces, the meninges and choroid plexus. In addition, monocytes infiltrate into the CNS parenchyma from circulation upon blood-brain barrier breakdown after CNS injury and inflammation. Although several markers, such as CD11b and ionized calcium-binding adapter molecule 1 (Iba1), are frequently used as microglial markers, they are also expressed by other types of myeloid cell and microglia-specific markers were not defined until recently. Previous transcriptome analyses of isolated microglia identified a transmembrane lectin, sialic acid-binding immunoglobulin-like lectin H (Siglec-H), as a molecular signature for microglia; however, this was not confirmed by histological studies in the nervous system and the reliability of Siglec-H as a microglial marker remained unclear. Here, we demonstrate that Siglec-H is an authentic marker for microglia in mice by immunohistochemistry using a Siglec-H-specific antibody. Siglec-H was expressed by parenchymal microglia from developmental stages to adulthood, and the expression was maintained in activated microglia under injury or inflammatory condition. However, Siglec-H expression was absent from CNS-associated macrophages and CNS-infiltrating monocytes, except for a minor subset of cells. We also show that the Siglech gene locus is a feasible site for specific targeting of microglia in the nervous system. In conclusion, Siglec-H is a reliable marker for microglia that will allow histological identification of microglia and microglia-specific gene manipulation in the nervous system

Évolution des récifs coralliens antillais sous l\u27influence de facteurs anthropiques et du changement climatique global

L\u27état de santé des récifs coralliens des Antilles françaises a commencé à se dégrader rapidement à partir du début des années 80 à la fois sous l\u27influence des actions anthropiques et des effets liés au changement climatique global agissant en synergie