Station de Recherche Océanographiques et Sous-marines
Recent publications
This study investigated for the first time the oxidative biomarkers responses in all larval stages of sea urchin. The contamination effects were reproduced by using contaminated seawater to concentrations measured in the area adjacent to an old asbestos mine at factors of 5 and 10. The results suggested that the concentrations were not sufficiently high to induce a major oxidative stress. The biometric differences make this method a more sensitive approach for assessing the effects on sea urchin larvae. Measurements of specific activities of antioxidant enzymes at each stage suggested a high capacity of the larvae to respond to oxidative stress. This normal activity of the organism must be considered in future research. This work also highlighted the importance of spawners provenance in ecotoxicological studies. These data are essential to better understand the stress responses of sea urchin larvae and provide baseline information for later environmental assessment research.
The Eastern Corsican Coast (ECC) is distinguished by its shallow sandy shelf, extensive Posidonia seagrass meadows, and the relatively limited exploitation of fish in this region. To understand ECC trophic functioning and the effects of fishing in this region of the Mediterranean Sea, we applied the Ecopath and EcoTroph approaches. Our model encompassed 5 groups of primary producers and detritus, 14 invertebrate groups, two groups of Chondrichthyes, 16 teleost groups, one seabird group, and one group of cetaceans. The ECC ecosystem was structured into five trophic levels, regulated top–down by Sphyraenidae, Epinephelus marginatus, and Dentex dentex. The ecosystem displayed a high degree of benthic–pelagic coupling, confirmed by keystone groups/species located at intermediate trophic levels (Seriola dumerilii, planktivorous teleosts, benthic cephalopods, shrimps, zooplankton). The ECC demonstrated the lowest exploitation rate (F/Z) of all exploited Mediterranean ecosystems, with trawling representing 55% of catches, followed by the lobster net (27%) and fish net (18%) fisheries. Catches often included untargeted groups—often discarded dead—in particular sharks and rays, and several protected species. Moreover, Palinurus elephas, Scorpaena scrofa, and Dentex dentex had elevated F/Z values, highlighting their vulnerabilities to fishing. Although the fishing simulations suggested that the ECC could support a greater exploitation, they also revealed that these fisheries have a marked impact on upper trophic levels. Our study draws attention to the critical habitat the ECC provides for Chondrichthyes, evidenced by the significant biomass for these taxa and the low fishing pressure relative to other exploited Mediterranean systems. This first modelling of the ECC is an initial step towards modelling all Corsican marine ecosystems to serve as a guide for preserving these ecosystems through appropriate management measures.
Health councils recommend a higher consumption of aquatic resources because of the health benefits associated with these kinds of food. Due to its nutritional quality, fish derived from marine environment is one of the major contributors to a healthy human nutrition. This study aims to assess the fatty acid profile and nutritional composition of cultivated and wild sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) from Corsica (Mediterranean region). In both marine species, fatty acid composition showed that total polyunsaturated fatty acids were higher in cultivated fish than in wild fish. Saturated fatty acids were higher in wild fish, which had also a higher level of monounsaturated fatty acids. Regardless of species and origin, the predominant fatty acids were palmitic acid in saturated fatty acids and oleic acid in monounsaturated fatty acids. The polyunsaturated fatty acids in cultivated fish were mainly represented by linoleic acid, followed by eicosapentaenoic and docosahexaenoic acids. The n-3/n-6 ratio in cultivated fish is in accordance with the recommended range for a healthy human diet. Based on the nutritional contribution in terms of eicosapentaenoic and docosahexaenoic acids levels, this study pointed out that sea bass and sea bream cultivated in Corsica are seafood with good nutritional qualities for human health.
Mangrove forests are impacted by a large range of anthropogenic activities that challenge their functioning. For example, domestic wastewater (WW) discharges are known to increase vegetation growth but recent studies indicate that they have negative effects on benthic macrofauna, especially on mangrove crabs, these ecosystem engineers playing a key role on the functioning of the mangrove. In experimental areas regularly receiving WW at low tide (Mayotte Island, Indian Ocean), a drastic decrease in burrowing crab density has been reported. In this context, the individual behavioural and physiological responses of the fiddler crab Paraleptuca chlorophthalmus exposed to short-term (6 h) pulse of WW and ammonia-N (as a potential proxy of WW) were investigated. This species is one of the most sensitive to WW within the mangrove crab community. For the behavioural experiment, crabs could choose between the aquatic and aerial environment. Individual metabolic rate (O2 consumption) was monitored after 6 h of exposure in WW or ammonia-N. Aerobic and anaerobic metabolic markers (citrate synthase and lactate dehydrogenase activities, respectively) were also evaluated. Results indicate that crabs exposed to WW are more active and mobile than controls after 3 h. Crabs actively emersed from WW and reduced their activity and mobility after 6 h. A higher metabolic rate in WW occurred immediately (t = 0 h), 3 and 6 h after WW exposure, with also, a burst in aerobic bacterial consumption in WW, but no effect of ammonia-N. No effect of WW or ammonia-N was observed on enzymatic aerobic and anaerobic metabolic markers. Therefore, short-term pulses with domestic polluted wastewater trigger quick behavioural and metabolic responses that could be deleterious if prolonged. These results could contribute to the understanding of the community-scale changes observed in benthic macrofauna after several years of regular domestic pollution pulses.
Small-scale fishery represents 83% of the Mediterranean fleet. Yet, its evaluation is made difficult by a scattered fishing effort, especially on large islands with remote fishing harbours. Corsica is considered as one of the area with the lowest fishing pressure in the Mediterranean and is mainly characterized by a small-scale fishery (SSF). The present study focuses on the characterization of Corsican SSF main metiers in relation to some key aspects of the fishery such as the targeted species, composition of conserved and discarded catches, factors impacting the catch per unit effort (CPUE) and the estimation of annual production. For this purpose, an intensive 2-year-sampling of 23% of the Corsican fleet was carried out. A total of four main metiers (fish net, spiny lobster net, bottom longline and pelagic longline) were identified and 128 species were recorded. Species composition of conserved and discarded catches of each metier revealed significant differences between all metiers, with pelagic longlines differentiating the most compared to other metiers. The analysis of the influence of different variables (technical fishing specifications, environmental and spatio-temporal parameters) revealed an impact of the fishing time on discarded catch for fish nets and spiny lobster nets and a spatial effect throughout Corsica micro-regions for both conserved and discarded catches for these two metiers. This study provides new knowledge on the characteristics of SSF effort and catch in Corsica as a reference area for the Mediterranean. These data can now be implemented in the assessment of its fisheries resources. The complexity of this fishery should be taken into account for any future management policies of artisanal fishing at a local, national and international scale in the Mediterranean.
The occurrence of microplastics (MPs) was investigated in the Arvand River (Iran). The Arvand River (200 Km) is a major water body that flows through land with diverse use and it meets the Persian Gulf. This study constitutes the first assessment of MP pollution in the Arvand river. MP monitoring has been carried out in 24 stations located along the river. The MP pollution found ranged between 1 and 291 items·L⁻¹ and 70 to 15,620 items·Kg⁻¹ (dw), in water and sediment, respectively. The majority of MPs were fibers, black/Gy and yellow/orange in color, and mainly 250–500 μm and >1000 μm in size. Polyethylene terephthalate (PET), polypropylene (PP), nylon (NYL), high-density polyethylene (HDPE), and polystyrene (PS) were found in sediment samples. All these polymers, except HDPE, were also identified in the water samples. Polyethylene terephthalate (PET) and polypropylene (PP) were dominant in the water samples; whereas PET and polystyrene (PS) were the most abundant in the sediments. The vicinity of urban wastewater effluents could be behind MP pollution in both water and sediments. Significant differences (p < 0.05) of MP concentrations were affected by different land uses when comparing MP levels in undisturbed natural area with urban areas. A strong correlation between MP fibers and fragments found with PCA biplots revealed their similar distribution in water. In the sediment samples, fiber and fragment MP particles were significantly correlated with colloidal particles (e.g., clay and organic matter) suggesting a relevant role of colloidal particles in the aquatic ecosystem of the Arvand River in transporting MPs. This study contributes to the better understanding of the presence of MP in major rivers, which are systems that have been scarcely investigated for this type of pollution, and it can inform interventions to reduce MP inputs to the river and sea.
Several experiments were performed using larvae of Paracentrotus lividus (Lamarck, 1816) in order to determine the consequences of different chronic contamination with mixtures of (i) fifteen trace elements from concentrations measured in the world ocean seawater, and (ii) seven trace elements from contamination resulting from mining. To predict the impact of increased marine pollution, higher concentrations were also used. These bioassays were conducted using spawners collected from Calvi (reference site, Corsica), and Albo (mining area, Corsica). The effects of trace elements have been studied on the entire larval development. The results show wider arms and delayed development as the number and concentration of trace elements increases. Therefore, the synergy between the different trace elements is of paramount importance with regard to the impact on organisms. Probably due to a hormesis phenomenon, larvae contaminated with seven trace elements at average concentrations developed more quickly. This work also highlighted the importance of the origin of spawners in ecotoxicological studies. To our knowledge, this is the first study to investigate the effects of such a broad combination of trace elements for chronic contamination on the entire larval stage of Paracentrotus lividus.
1. Sound production represents an integral part of social communication in many teleost fish; however, few studies have investigated the structure, organization and variability of fish sounds at the community level. 2. Fish acoustic community structure was recorded simultaneously in three sites located along the Mediterranean basin within the endemic habitat of Posidonia oceanica seagrass beds. Acoustic diversity and species-specific sound features were expected to differ between locations. We predicted that, in communities characterized by higher acoustic richness, fish species would specialize in their use of acoustic resources (i.e. realized acoustic niche compression), while the overall allocation of resources within the community signal space would expand. 3. The fish acoustic communities inhabiting Posidonia beds were characterized by the same main contributors (the /Kwa/, Ophidion rochei and Sciaena umbra sound types). However, their relative occurrence, abundances and use of acoustic resources were site-specific. Acoustic diversity differed between geographic locations. The range of spectral and temporal resources exploited by the fish acoustic community was wider in sites where acoustic richness was at its highest score. Ophidion rochei was highly specialized in its use of temporal resources where acoustic richness was higher, whilst S. umbra appeared less efficient in specializing the use of spectral and temporal resources. 4. By showing that the same species can exploit different acoustic resources between locations, this study supports the concept of Acoustic Niche plasticity (i.e. plasticity of acoustic resources allocation within a species). The results suggest that the degree of acoustic niche plasticity might be determined by the species-specific degree of sound-producing system plasticity. In turn, different degrees of acoustic niche plasticity might determine different species-specific levels of acoustic adaptability to changing biotic or environmental conditions.
Plastic debris are accumulating in the marine environment and aggregate microorganisms that form a new ecosystem called the plastisphere. Better understanding the plastisphere is crucial as it has self-sufficient organization and, carries pathogens or organisms that may be involved in the pollutant adsorption and/or plastic degradation. To date, the plastisphere is mainly described at the taxonomic level and the functioning of its microbial communities still remains poorly documented. In this work, metagenomic and metaproteomic analyzes were performed on the plastisphere of polypropylene and polyethylene plastic debris sampled on a pebble beach from the Mediterranean Sea. Our results confirmed that the plastisphere was organized as self-sufficient ecosystems containing highly active primary producers and heterotrophs and predators such as nematode. Interestingly, the chemical composition of the polymer did not impact the structure of the microbial communities but rather influenced the functions expressed. Despite the fact that the presence of hydrocarbon degrader bacteria was observed in the metagenome, polymer degradation metabolisms were not detected at the protein level. Finally, hydrocarbon degrader (i.e., Alcanivorax) and pathogenic bacteria (i.e., Vibrionaceae) were observed in the plastispheres but were not very active as no proteins involved in polymer degradation or pathogeny were detected. This work brings a new insight into the functioning of the microbial plastisphere developed on plastic marine debris.
Mangrove crabs are ecosystem engineers through their bioturbation activity. On Mayotte Island, the abundance of Neosarmatium africanum decreased in wastewater-impacted areas. Previous analyses showed that global crab metabolism is impacted by wastewater, with a burst in O2 consumption that may be caused by osmo-respiratory trade-offs since gill functioning was impacted. As the hepatopancreas is a key metabolic organ, the purpose of this study was to investigate the physiological effects of wastewater and ammonia-N 5-h exposure on crabs to better understand the potential trade-offs underlying the global metabolic state. Catalase, superoxide dismutase, glutathione S-transferase, total digestive protease, and serine protease (trypsin and chymotrypsin) activities were assessed. Histological analyses were performed to determine structural modifications. No effect of short-term wastewater and ammonia-N exposure was found in antioxidant defenses or digestive enzyme activity. However, histological changes of B-cells indicate an increase in intracellular digestive activity through higher vacuolization processes and tubule dilation in wastewater-exposed crabs.
Corsican marine aquaculture is one of the highest contributors of fish production in France, which may result in environmental perturbations caused by organic matter (OM) accumulation under fish farms and impacting natural communities. This study aimed to (1) characterise the environmental conditions at two different fish farms, (2) monitor the response of benthic foraminiferal species to this activity, and (3) assess the accuracy of existing foraminiferal biotic indices. In 2017, sea floor sediment was sampled in transects from two Corsican fish farms for living foraminiferal and sedimentary analyses. Four indices were calculated and compared: exp(H′bc), Foram-AMBI, Foram Stress Index and TSI-Med. A significant increase in total organic carbon (TOC) has been shown, mainly below the fish cages. Communities were characterized by a shift from high density, opportunistic and tolerant species under the cages to lower densities and more sensitive species further away. According to their distribution patterns along the TOC gradient, we propose to update the ecological group classification of seven species to improve Foram-AMBI’s accuracy and sensitivity: Triloculina oblonga and Quinqueloculina lamarckiana to Ecological Group (EG) I; Rosalina bradyi to EGIII; and Bolivina dilatata, Bulimina aculeata and Quinqueloculina stalkeri to EGIV. We recommend prioritising the use of TSI-Med and Foram-AMBI with the updated list to assess ecological quality in coastal waters of the Mediterranean Sea.
Coastal fishes are not only valuable elements of marine biodiversity, but they also play an important ecological role in the functioning of coastal ecosystems: food resource, transfer of nutrients, predators. Therefore, data on the compositions of fish assemblages are of great importance. The objectives of the present study were to (i) define the faunistic characteristics of a typical fish community on the Mediterranean coast; (ii) investigate spatiotemporal changes in fish assemblages. Based on a set of indices (Fast protocol) and a long-term data set (6 years, 612 visual counts, 154 h of diving), changes in coastal fish communities were analyzed. Our results indicated that there was a significant shift in fish community structure, with a general decline of the calculated indices. In our study, part of the observed variability in fish assemblage structure could be due to different factors as site location and sampled year. The changes in the fish assemblages associated with inter-annual fluctuations observed in this study also provide important insights into how fish communities may change under environmental and anthropogenic influences.
The biological processes underlying zinc homeostasis are targets for genetic improvement of crops to counter human malnutrition. Detailed phenotyping, ionomic, RNA-Seq analyses and flux measurements with ⁶⁷Zn isotope revealed whole plant molecular events underlying zinc homeostasis upon varying zinc supply and during zinc resupply to starved Brachypodium distachyon (Brachypodium) plants. Although both zinc deficiency and excess hindered Brachypodium growth, accumulation of biomass and micronutrients into roots and shoots differed depending on zinc supply. The zinc resupply dynamics involved 1893 zinc-responsive genes. Multiple ZIP transporter genes and dozens of other genes were rapidly and transiently down-regulated in early stages of zinc resupply, suggesting a transient zinc shock, sensed locally in roots. Notably, genes with identical regulation were observed in shoots without zinc accumulation, pointing to root-to-shoot signals mediating whole plant responses to zinc resupply. Molecular events uncovered in the grass model Brachypodium are useful for the improvement of staple monocots. This article is protected by copyright. All rights reserved.
In the present study the concentrations of 12 trace elements (TEs): As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn were quantified in muscle and, where possible, liver tissues, of six commercially important marine species including fish (Euryglossa orientalis, Sardinella longiceps, Carcharhinus dussumieri), crustacean (Portunus armatus, Thenus orientalis) and mollusc (Sepia pharanois) collected from the North Persian Gulf. Arsenic, copper, iron, and zinc were observed to be the most dominant TEs in muscle and liver tissues of all the species. In comparing with the maximum permissible limits (MPL) set by international organizations for seafood including FAO (1983), EC (2007), FAO/WHO (2007), and USEPA (2011), the mean concentrations of As, Cd in all the species and Mn, Zn, and Hg in some species exceeded their MPL limits. The relationships between TEs concentration and biometric indices (body length and weight) varied markedly among the TEs within both species and tissues. Estimated daily intake (EDI) results in comparison with values of the tolerable daily intake (TDI) confirmed that consumption of T. orientalis, C. dussumieri and S. pharanois from the sampled locations exceed their maximum values for As, Cd, Hg, and Se established for children.
Marine aquaculture provides undoubted economic benefits and diverts a proportion of fishing pressure on wild stocks. However, it is known to strongly impact marine life with the Mediterranean region, which is densely populated and urbanized with a strong demand for seafood, especially sensitive to marine aquaculture pressures. Marine aquaculture not only has adverse effects on the aquatic environment, but also on the associated biota. Currently available scientific observations cannot clearly identify the positive or negative effects of marine aquaculture on wildlife. Because of this limited scientific knowledge, we felt the time was ripe for a special issue to bring together recent research on the impacts of marine aquaculture on marine biota—with particular emphasis on the Mediterranean as a laboratory in this assessment—and on proposed mitigation measures to reduce the potential negative effects.
This paper presents a new non-destructive sampling technique that consists of cutting all of the leaves of a Posidonia oceanica shoot (with scissors) just above the ligula of the external leaves. Developed in an undisturbed meadow in Corsica (France) at depths of 12–15 m, this sampling technique is called the Non-Destructive Shoot sampling Method (NDSM). The results of using this method indicate that most biometric parameters and relevant water quality indices can be measured and calculated from seagrasses sampled using the NDSM. It was determined that sampling shoots using the NDSM ensured a 100% survival rate. Notably, the NDSM allowed sampled shoots to grow back to lengths similar to those of an adjacent control meadow within three months. Biochemical analyses indicated that meadow portions and seagrass leaves regrown after NDSM sampling differed little in chemical composition (C, N and P and essential metal micronutrients Fe, Cu, Zn, Mn, Ni and Mo) to control seagrasses. Thus, the NDSM limits the negative effects of the sampling. Although not lethal to the plant, sampling seagrasses according to the NDSM requires exemption from the competent authority according to local, regional or national regulations for each protected species.
Although Argyrosomus regius (Asso, 1801) counts among the most appreciated and increasingly consumed fish species in Europe, little information is available on its flesh quality. This research concerns both healthy aquatic resource diversification and good nutritional quality. It is the first study to evaluate the quality of A. regius flesh from Mediterranean aquaculture. It aims to assess the concentration of 19 trace elements and to determine the fatty acid profile of this fish farmed in the Mediterranean Sea and to discuss human exposure risks. The nutritional intake of oligoelements (selenium (Se), zinc (Zn), and chromium (Cr)) and the mean concentrations of contaminants (arsenic (As), barium (Ba), cadmium (Cd), lead (Pb), and tin (Sn)) in A. regius muscles are, respectively, above and below recommended regulatory standards set by the international legislation. Additionally, the low fat content in its muscle mass and its high level of docosahexaenoic acid (C22: 6 n-3; DHA) and, to a lesser extent, eicosapentaenoic acid (C20: 5 n-3; EPA) confers satisfying nutritional qualities. This study allowed to conclude that meager can be considered as a source of seafood with good nutritional qualities for human health.
1 There is concern across the International Council for the Exploration of the Sea (ICES) region that a consideration of vulnerable components and the wider support mechanisms underpinning benthic marine ecosystems may be lacking from the process of marine protected area (MPA) designation, management and monitoring. 2 In this study, MPAs across six European ecoregions were assessed from a benthic ecology perspective. The study included 102 MPAs, designated by 10 countries, and focused on three aspects regarding the role of the benthos in: (i) the designation of MPAs; (ii) the management measures used in MPAs; and (iii) the monitoring and assessment of MPAs. 3 Qualitative entries to a questionnaire based on an existing framework (EU project ‘Monitoring Evaluation of Spatially Managed Areas’, (MESMA) were collected by 19 benthic experts of the ICES Benthic Ecology Working Group. A pedigree matrix was used to apply a numerical scale (score) to these entries. 4 The results showed clear differences in scores between ecoregions and between criteria. The designation-phase criteria generally achieved higher scores than the implementation-phase criteria. Poor designation-phase scores were generally reiterated in the implementation-phase scores, such as scores for assessment and monitoring. 5 Over 70% of the MPA case studies were found to consider the benthos to some extent during selection and designation; however, this was not followed up with appropriate management measures and good practice during the implementation phase. 6 Poor spatial and temporal coverage of monitoring and ineffective indicators is unlikely to pick up changes caused by management measures in the MPA. There is concern that without adequate monitoring and adaptive management frameworks, the MPAs will be compromised. Also, there could be an increased likelihood that, with regard to the benthos, they will fail to meet their conservation objectives. 7 This assessment was successful in highlighting issues related to the representation and protection of the benthos in MPAs and where changes need to be made, such as expanding the characterization and monitoring of benthic species or habitats of interest. These issues could be attributable to an ongoing process and/or an indication that some MPAs only have ‘paper protection’.
Coastal vegetated wetlands—mangroves, saltmarshes, and seagrass beds, hereafter called coastal wetlands—are marine ecosystems constituted of rooted macrophytes living intertidally or subtidally. They occupy a narrow fringe along the shores of all continents except Antarctica. They are profoundly important to human livelihoods and the regulation of physical, chemical, and biological processes, and thus for coastal resilience. Nevertheless, ongoing declines in the cover of coastal wetlands will undoubtedly diminish the ecosystem services they provide. Lack of research knowledge in many areas of coastal wetland functioning hampers decision-making processes concerning their management. We felt the time was ripe for a special issue to bring together recent research into the functioning of coastal wetlands.
The current study examined the concentrations of ten trace elements (TE) (nickel, chromium, cadmium, iron, zinc, manganese, aluminum, copper, selenium and lead) in the edible tissue of the Ark shell Arca noae (L. 1758) from a Mediterranean coastal lagoon, the Bizerte lagoon during 2013–2014. The analysis of several redox status biomarkers, metallothioneins (MTs), malondialdehyde (MDA), glutathione peroxidase (GPx), reduced glutathione (GSH) and acetylcholinesterase (AChE), was monitored as a response to TE bioaccumulation and environmental parameters variability. Significant differences (p < 0.05) were observed between mean seasonal TE concentrations in A. noae soft tissue. The highest TE concentrations in A. noae soft tissues were recorded during summer, which coincided with the increase of body dry weight (BDW) and the gonad index (GI). During this season, biomarker responses were enhanced, revealing significant increases of MTs, MDA and GSH levels as well as GPx activity in A. noae tissues, while a decrease of AChE activity was observed. The levels of TE analyzed in A. noae and several parameters used to assess the potential human risk (estimated weekly intake, target hazard quotient and target hazard risk) were lower than the permissible limits for safe seafood consumption. Consequently, this shellfish can be considered safe for human consumption. This preliminary study presents prospects for the valorization of this seafood product in Tunisia’s food sector. It also gives basal information for future environmental assessment studies in which A. noae could be used as early warning tools in the field of biomonitoring programs and confirms the usefulness of biomarkers to monitor the health status of aquatic organisms.
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