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Alfonso, S., Gesto, M., & Sadoul, B. (2020). Temperature increase and its effects on fish stress physiology in the context of global warming. J. Fish Biol., .
Résumé: The capacity of fishes to cope with environmental variation is considered to be a main determinant of their fitness and is partly determined by their stress physiology. By 2100, global ocean temperature is expected to rise by 1-4 degrees C, with potential consequences for stress physiology. Global warming is affecting animal populations worldwide through chronic temperature increases and an increase in the frequency of extreme heatwave events. As ectotherms, fishes are expected to be particularly vulnerable to global warming. Although little information is available about the effects of global warming on stress physiology in nature, multiple studies describe the consequences of temperature increases on stress physiology in controlled laboratory conditions, providing insight into what can be expected in the wild. Chronic temperature increase constitutes a physiological load that can alter the ability of fishes to cope with additional stressors, which might compromise their fitness. In addition, rapid temperature increases are known to induce acute stress responses in fishes and might be of ecological relevance in particular situations. This review summarizes knowledge about effects of temperature increases on the stress physiology of fishes and discusses these in the context of global warming.
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Blondeau-Bidet, E., Hiroi, J., & Lorin-Nebel, C. (2019). Ion uptake pathways in European sea bass Dicentrarchus labrax. Gene, 692, 126–137.
Résumé: Ion uptake mechanisms are diverse in fish species, certainly linked to duplication events that have led to the presence of a multitude of paralogous genes. In fish, Na+ uptake involves several ion transporters expressed in different ionocyte subtypes. In the European sea bass Dicentrarchus labrax, several key transporters potentially involved in Na+ uptake have been investigated in seawater (SW) and following a 2 weeks freshwater (FW) acclimation. Using gel electrophoresis, we have shown that the Na+/H+-exchanger 3 (nhe3, slc9a3) is expressed in gills and kidney at both salinities. Quantitative realtime PCR analysis showed a significantly higher nhe3 expression in fresh water (FW) compared to SW. Its apical localization in a subset of gill ionocytes in freshwater-acclimated fish supports the role of NHE3 in Na+ uptake. Interestingly, NHE3-immunopositive cells also express basolateral Na+/K+/2Cl− cotransporter 1 (NKCC1) and are mainly localized in gill lamella. Among the three nhe2 (slc9a2) paralogs, only nhe2c shows differential branchial expression levels with higher mRNA levels in SW than in FW. The increased branchial expression of the ammonia transporter rhcg1 (Rhesus protein), nhe3 and cytoplasmic carbonic anhydrase (cac) in FW could indicate the presence of a functional coupling between ion transporters to form a Na+/NH4+ exchange complex. Acid-sensing ion channel 4 (asic4) seems not to be expressed in sea bass gills. Na+/Cl- cotransporter (ncc2a or ncc-like) is about three times more expressed in FW compared to SW suggesting coupled Na+ and Cl− uptake in a subset of gill ionocytes. Besides the main pump Na+/K+-ATPase, branchial NCC2a and NHE3 may be key players in ion uptake in sea bass following a long-term freshwater challenge.
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Cardoso de Melo, C., Cavalcanti Soares, A. P., Pelage, L., Eduardo Nole, L., Fredou, T., Lira, A. S., et al. (2020). Haemulidae distribution patterns along the Northeastern Brazilian continental shelf and size at first maturity of the most abundant species. Reg. Stud. Mar. Sci., 35, 101226.
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Chiarello, M., Auguet, J. - C., Bettarel, Y., Bouvier, C., Claverie, T., Graham, N. A. J., et al. (2018). Skin microbiome of coral reef fish is highly variable and driven by host phylogeny and diet. Microbiome, 6, 147.
Résumé: Background: The surface of marine animals is covered by abundant and diversified microbial communities, which have major roles for the health of their host While such microbiomes have been deeply examined in marine invertebrates such as corals and sponges, the microbiomes living on marine vertebrates have received less attention. Specifically, the diversity of these microbiomes, their variability among species, and their drivers are still mostly unknown, especially among the fish species living on coral reefs that contribute to key ecosystem services while they are increasingly affected by human activities. Here, we investigated these knowledge gaps analyzing the skin microbiome of 138 fish individuals belonging to 44 coral reef fish species living in the same area. Results: Prokaryotic communities living on the skin of coral reef fishes are highly diverse, with on average more than 600 OTUs per fish, and differ from planktonic microbes. Skin microbiomes varied between fish individual and species, and interspecific differences were slightly coupled to the phylogenetic affiliation of the host and its ecological traits. Conclusions: These results highlight that coral reef biodiversity is greater than previously appreciated, since the high diversity of macro-organisms supports a highly diversified microbial community. This suggest that beyond the loss of coral reefs-associated macroscopic species, anthropic activities on coral reefs could also lead to a loss of still unexplored host-associated microbial diversity, which urgently needs to be assessed.
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Cresson, P., Fabri, M. - C., Bouchoucha, M., Brach Papa, C., Chavanon, F., Jadaud, A., et al. (2014). Mercury in organisms from the Northwestern Mediterranean slope: Importance of food sources. Science of The Total Environment, 497-498, 229–238.
Résumé: Mercury (Hg) is a global threat for marine ecosystems, especially within the Mediterranean Sea. The concern is higher for deep-sea organisms, as the Hg concentration in their tissues is commonly high. To assess the influence of food supply at two trophic levels, total Hg concentrations and carbon and nitrogen stable isotope ratios were determined in 7 species (4 teleosts, 2 sharks, and 1 crustacean) sampled on the upper part of the continental slope of the Gulf of Lions (Northwestern Mediterranean Sea), at depths between 284 and 816 m. Mean Hg concentrations ranged from 1.30 ± 0.61 to 7.13 ± 7.09 μg g− 1 dry mass, with maximum values observed for small-spotted catshark Scyliorhinus canicula. For all species except blue whiting Micromesistius poutassou, Hg concentrations were above the health safety limits for human consumption defined by the European Commission, with a variable proportion of the individuals exceeding limits (from 23% for the Norway lobster Nephrops norvegicus to 82% for the blackbelly rosefish Helicolenus dactylopterus). Measured concentrations increased with increasing trophic levels. Carbon isotopic ratios measured for these organisms demonstrated that settling phytoplanktonic organic matter is not only the main source fueling trophic webs but also the carrier of Hg to this habitat. Inter- and intraspecific variations of Hg concentrations revealed the importance of feeding patterns in Hg bioaccumulation. In addition, biological parameters, such as growth rate or bathymetric range explain the observed contamination trends.
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