French Research Institute for Exploitation of the Sea
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Toward the use of innovative environmentally sustainable feed in organic aquaculture: Impact on growth performance, health, and welfare of gilthead seabream (Sparus aurata)
No full textOrganic aquaculture aims to provide sustainable aquatic products, and utilizing innovative aquafeeds with less fish meal is crucial. This study evaluated the impact of a cost‐effective and environmentally friendly diet (51% replacement with plant/animal protein sources like fermented soy, pea, krill, squid, and yeast meals) on gilthead seabream (Sparus aurata) growth, health, and welfare using a multiparametric approach (growth, swimming activity, blood health, and welfare indicators). The innovative diet showed no adverse effects on growth performance and survival. Hematological and biochemical blood indicators demonstrated minimal alterations, with only lactate levels increasing, suggesting no compromise in overall welfare. Immune features indicated a potentially stronger innate immune response in fish fed the innovative diet, as shown by higher levels of total proteins, alpha 1, and beta 1. Finally, a slight difference was observed in swimming activity between diets, but primarily occurred at the end of the day. A comprehensive multiparametric analysis and multi‐criteria decision analysis indicated better global welfare and health status with the innovative diet compared to the control. While the innovative diet showed promising results for gilthead seabream organic aquaculture, further long‐term investigations are necessary to explore the underlying causes of the observed immune parameter changes
Assessment of spatial distribution of organic contaminants and metallic compounds on a tropical island’ coral reef fish communities
No full textThe New Caledonian archipelago is an important hotspot of marine biodiversity. Due to mining activities, urbanization, and industrialization, significant amounts of contaminants are discharged into the lagoon. This study analysed the concentrations, spatial distribution, and potential drivers of 14 metallic compounds and trace elements (MTEs) and 22 persistent organic pollutants (POPs) in ~400 coral reef fish sampled from various sites around New Caledonia, across a gradient from mining centers to remote, uninhabited locations. Boosted regression trees modelling explained between 61 and 86 % of the global variation in MTEs and POPs concentration. Fish body size emerged as the most important correlate of MTEs and POPs concentrations in coral reef fish. Monthly rainfalls were the second most important variable for POPs, whereas the reef area was the second variable explaining MTE concentrations. Our modelling approach allowed us to predict and map the distribution of concentrations at the fish community level for 17 contaminants (9 MTEs and 8 POPs). Predicted concentrations ranged from ~1.5 ng.g−1 (β-endosulfan) to ~11.5 μg.g−1 (Ni), and revealed a widespread contamination throughout the lagoon, from the coast to the barrier reef. Contamination by mining-related elements (Ni, Cr…) were clearly influenced by the surface area of mining registry and to lithology to a lesser extent, whereas Hg contamination strongly depended on biological variables. Our study is the largest of its kind at the archipelago scale, combining data on 36 contaminants in ~400 fish samples with a modelling framework offering insights into underlying processes and spatial data for policy use
Organotropism of metals and Zn Cu isotope ratios in hydrothermal vent mussels (Bathymodiolus) and sea snails (Ifremeria and Alviniconcha): Implications for bioaccumulation mechanisms
No full textThis study investigated metal organotropism and ZnCu isotopic compositions in hydrothermal vent mussels (Bathymodiolus sp.) and sea snails (Ifremeria sp. and Alviniconcha sp.). In mussels, bioaccumulation of Al, V, Cr, Mn, Fe, Co, Ni and Zn occurred mainly in the byssus and digestive gland, whereas Cu, As, Ag, Cd, and Pb were found in the gills, suggesting that bioaccumulation of these metals occurs via the respiratory system. In sea snails, the digestive glands tended to have higher metal concentrations than other organs. Zn showed higher intratissue isotope variability than Cu. For Cu isotopes, the digestive glands of vent mollusks had the highest δ65Cu values. However, while Zn concentrations were consistently elevated in the digestive glands, δ66Zn values did not exhibit a corresponding trend. In vent mussels, during sequenced transport or metal partitioning processes after accumulation via the gills and digestive glands, Zn and Cu concentrations decreased with isotopic fractionation, indicating that lighter isotopes are preferentially used. Both sea snail species differed from mussels in that they preferentially accumulated lighter Zn isotopes in the digestive glands with higher Zn content. The metal and isotopic signatures accumulated in the internal organs of hydrothermal vent mollusks suggest species-dependent dietary strategies and mechanisms of uptake, accumulation, and detoxification. Our findings related to the organotropism of Zn and Cu isotopes offer new insights into the bioavailability and bioaccumulation processes of hydrothermal vent mollusks
Urinary Schistosomiasis: the Corsican file
No full textSchistosomiasis, known as bilharzia, is a parasitic disease caused by trematodes of the genus Schistosoma, found primarily in Africa and pockets of the Middle East. Southern Europe seems to be a breeding ground for urogenital schistosomiasis emergence. Ten and five years have passed since the first and the last cases of urogenital schistosomiasis were identified in Corsica (patients who have bathed in the Cavu and/or Solenzara rivers between 2013 and 2019). Through a literature review, the authors aimed to clarify the epidemiological, clinical and diagnostic particularities of urinary schistosomiasis acquired in Corsica.La schistosomiase, connue sous le nom de bilharziose, est une maladie parasitaire causée par des trématodes du genre Schistosoma, que l'on trouve principalement en Afrique et dans certaines poches du Moyen-Orient. L’Europe du Sud semble être un terrain fertile pour l’émergence de la schistosomiase urogénitale. Dix et cinq ans se sont écoulés depuis que les premiers et derniers cas de schistosomiase urogénitale ont été identifiés en Corse (patients s'étant baignés dans les rivières Cavu et/ou Solenzara entre 2013 et 2019). A travers une revue de la littérature, les auteurs ont cherché à clarifier les particularités épidémiologiques, cliniques et diagnostiques de la schistosomiase urinaire contractée en Corse
Epibenthic communities' structure in St. Pierre Bank revealed by underwater video
No full textGiven the significant ecosystem services provided by benthic communities, monitoring their biodiversity enable to better understand how global changes would affect their structure in a context of biodiversity loss. Using underwater video transect, we characterize alpha and beta diversity of epibenthic communities, their structure and forcing factors in St. Pierre Bank; an area where marine benthos is still poorly documented. Video monitoring enables the detection of 74 different taxa belonging to eight phyla. Results highlighted three spatial entities of benthic assemblages distributed along a bathymetric gradient and primarily influenced by sedimentary types. In the southern and western area, rhodoliths beds substrate shelters the majority of echinoderms. The southern region was dominated by sea cucumber Cucumaria frondosa, whereas in the western area, brittle stars, and the green sea urchin Strongylocentrotus droebachiensis were dominant. Fishing activity was concentrated in the south, due to the presence of exploited sea cucumber. In contrast, the northern region featured patchy fine and soft substrates with a preponderance of giant scallop Placopecten magellanicus and sand dollar Echinarachnius parma. In addition to the contribution of environmental factors to the distribution of communities, this study highlights the complexity of several biotic interactions at the origin of these assemblages
Optimization of the Extraction Protocol for Pacific Ciguatoxins from Marine Products Prior to Analysis Using the Neuroblastoma Cell-Based Assay
No full textCiguatera poisoning (CP) is caused by the consumption of marine products contaminated with ciguatoxins (CTXs) produced by dinoflagellates of the genus Gambierdiscus. Analytical methods for CTXs, involving the extraction/purification of trace quantities of CTXs from complex matrices, are numerous in the literature. However, little information on their effectiveness for nonpolar CTXs is available, yet these congeners, contributing to the risk of CP, are required for the establishment of effective food safety monitoring programs. An evaluation of six extraction/purification protocols, performed with CTX3C spiked on fish flesh and a neuroblastoma cell-based assay (CBA-N2a), revealed recoveries from 6 to 45%. This led to the development of an optimized 3-day protocol designed for a large number of samples, with CTX1B and CTX3C eluting in a single fraction and showing recoveries of 73% and 70%, respectively. In addition, a reduction in adverse matrix effects in the CBA-N2a analyses was demonstrated with naturally contaminated specimens, increasing the sensitivity of the method, which now meets the very low guidance level recommended by international agencies. However, efforts are still required to reduce the signal suppression observed in LC-MS/MS analysis. This optimized protocol contributes to the technological advancement of detection methods, promoting food safety and improving CP risk assessment in marine products
Cross‐ecosystem trophic structure and benthic–pelagic coupling: Effects of depth, body size, and feeding guild
No full textUnderstanding how energy is transferred within and across ecosystems is essential to better understand drivers and future consequences of shifts in energy pathways. We used stable isotope ratios of 1932 fish individuals belonging to the 11 most abundant fish species collected across 300,000 km2 along the English Channel–Celtic Sea continuum. To examine cross‐ecosystem differences in trophic functioning, we assessed the effects of both extrinsic (depth) and intrinsic factors (body size and feeding guild) on resource use and trophic position of fish consumers. Positive relationships between trophic position and body size were observed for zoobenthivore and piscivore fishes, whereas the relationship was negative for benthivore fishes. Body size is thus an important structuring mechanism in the systems. Trophic position decreased with increasing depth for all levels of biological organization. The amplitude of the change between shallow and deep stations was equivalent to more than one trophic level for generalist planktivores and piscivores. In the shallow English Channel, the food web is marked by stronger coupling of benthic and pelagic habitats via diverse pathways, due to the proximity of benthic and pelagic species, whereas in the Celtic Sea, increasing depth leads to a decoupling of benthic and pelagic pathways. For piscivores, a consistent pattern of increasing dependence on benthic subsidies with increasing size and depth highlights the importance of large consumers coupling energy across food web compartments. This study describes the relationship between production and trophic functioning and provides an empirical ecological explanation for cross‐ecosystem differences in observed trophic structures
Regional sea level trend budget over 2004–2022
No full textClosure of the regional sea level trend budget is investigated over the 2004–2022 time span by comparing trend patterns from the satellite altimetry-based sea level with the sum of contributions, i.e. the thermosteric, halosteric, manometric and GRD (gravitational, rotational, and deformational fingerprints due to past and ongoing land ice melt) components. The thermosteric and halosteric components are based on Argo data (down to 2000 m). For the manometric component, two approaches are considered: one using GRACE/GRACE Follow-On satellite gravimetry data and the other using ocean reanalyses-based sterodynamic sea level data corrected for local steric effects. For the latter, six different ocean reanalyses are considered, including two reanalyses that do not assimilate satellite altimetry data. The results show significantly high residuals in the North Atlantic for both approaches. In a few other regions, small-scale residuals of smaller amplitude are observed and attributed to the finer resolution of altimetry data compared to the coarser resolution of data sets used for the components. The observed strong residual signal in the North Atlantic points to Argo-based salinity errors in this region. However, it is not excluded that other factors also contribute to the reported non-closure of the budget in this area
