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Navarro, J., Albo-Puigserver, M., Coll, M., Saez, R., Forero, M. G., & Kutcha, R. (2014). Isotopic discrimination of stable isotopes of nitrogen (δ15N) and carbon (δ13C) in a host-specific holocephalan tapeworm. Journal of Helminthology, 88(03), 371–375.
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Le Pape, O., DELAVENNE, J., & VAZ, S. (2014). Quantitative mapping of fish habitat: A useful tool to design spatialised management measures and marine protected area with fishery objectives. Ocean & Coastal Management, 87, 8–19.
Résumé: The delineation of essential fish habitats is necessary to identify, design and prioritize efficient marine protected area (MPA) networks with fishery objectives, capable, in addition to other possible objectives and functions of MPAs, of sustaining the renewal of marine living resources. Both the methods available to map essential fish habitats and the usefulness of these maps are discussed in this paper. Generally, the first step to obtain maps of essential fish habitats consists in choosing one of the numerous existing statistical approaches to build robust habitat suitability models linking relevant descriptors of the marine environment to the spatial distribution of fish presence or density. When these descriptors are exhaustively known, i.e. maps are available for each of them, geo-referenced predictions from these models and their related uncertainty may be imported into Geographic Information Systems for the quantitative identification and characterization of key sites for the marine living resources. The second part of this paper deals with the usefulness of such quantitative maps for management purposes. These maps allow for the quantitative identification of the different habitats that are required for these marine resources to complete their life cycles and enable to measure their respective importance for population renewal and conservation. The consequences of anthropogenic pressures – not only fishing but also land reclamation, aggregate extractions or degradation of habitat quality (e.g. nutrient excess or xenobiotics loadings, invasive species or global change) – on living resources, may also be simulated from such habitat models. These quantitative maps may serve as input in specific conservation planning software based on the systematic conservation approach. Fish habitat maps thus may help decision makers to select relevant protection areas and design coherent MPA networks which objectives are to sustain fishing resources and fisheries.
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Johnson, K. E., Perreau, L., Charmantier, G., Charmantier-Daures, M., & Lee, C. E. (2014). Without Gills: Localization of Osmoregulatory Function in the Copepod Eurytemora affinis. Physiological and Biochemical Zoology, 87(2), 310–324.
Résumé: The Pancrustacea, which include crustaceans and hexapods, have successfully colonized marine, freshwater, and terrestrial habitats. While members of the class Malacostraca (e.g., crabs, shrimp) often display immense osmoregulatory capacities, more basally branching crustaceans (e.g., copepods, branchiopods) tend to possess less-specialized osmoregulatory structures that have been poorly characterized. Remarkably, some of these more basal taxa have also colonized diverse habitats. For instance, the copepod Eurytemora affinis has recently invaded freshwater habitats multiple times independently but lack obvious osmoregulatory structures. To explore localization of ion exchange, we performed silver staining, immunohistochemical staining, and transmission electron microscopy. Our results revealed localization of ion transport within the maxillary glands and on four pairs of swimming legs. Silver staining revealed ion exchange at the maxillary pores and on the endopods and exopods of swimming legs P1 through P4. Immunohistochemical assays localized ion transport enzymes V-type H+-ATPase and Na+/K+-ATPase in the maxillary glands and swimming legs as well. Finally, transmission electron microscopy identified specialized ionocytes within these anatomical regions. These investigations uncovered novel osmoregulatory structures at the swimming legs, which we designate the “Crusalis organs.” Our findings identified specific tissues specialized for ion transport, potentially enabling this small crustacean to rapidly transition into freshwater habitats.
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Fouilland, E., Tolosa, I., Bonnet, D., Bouvier, C., Bouvier, T., Bouvy, M., et al. (2014). Bacterial carbon dependence on freshly produced phytoplankton exudates under different nutrient availability and grazing pressure conditions in coastal marine waters. FEMS microbiology ecology, 87(3), 757–769.
Résumé: The effects of grazing pressure and inorganic nutrient availability on the direct carbon transfer from freshly produced phytoplankton exudates to heterotrophic bacteria biomass production were studied in Mediterranean coastal waters. The short-term incorporation of (1)(3)C (H(1)(3)CO(3)) in phytoplankton and bacterial lipid biomarkers was measured as well as the total bacterial carbon production (BP), viral lysis and the microbial community structure under three experimental conditions: (1) High inorganic Nutrient and High Grazing (HN + HG), (2) High inorganic Nutrient and Low Grazing (HN + LG) and (3) under natural in situ conditions with Low inorganic Nutrient and High Grazing (LN + HG) during spring. Under phytoplankton bloom conditions (HN + LG), the bacterial use of freshly produced phytoplankton exudates as a source of carbon, estimated from (1)(3)C enrichment of bacterial lipids, contributed more than half of the total bacterial production. However, under conditions of high grazing pressure on phytoplankton with or without the addition of inorganic nutrients (HN + HG and LN + HG), the (1)(3)C enrichment of bacterial lipids was low compared with the high total bacterial production. BP therefore seems to depend mainly on freshly produced phytoplankton exudates during the early phase of phytoplankton bloom period. However, BP seems mainly relying on recycled carbon from viral lysis and predators under high grazing pressure.
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Espinoza, P., & Bertrand, A. (2014). Ontogenetic and spatiotemporal variability in anchoveta Engraulis ringens diet off Peru. Journal of Fish Biology, 84(2), 422–435.
Résumé: In this study, historical data available since 1954 were used to get new insight to ontogenetic and spatiotemporal variability in Peruvian anchovy or anchoveta Engraulis ringens diet. Whatever the period, E. ringens foraged mainly on macrozooplankton and the importance of euphausiids in E. ringens diet appears directly related to euphausiids abundance. This bottom-up effect is also observed at smaller scale because the euphausiids fraction increased with E. ringens total length and euphausiids accessibility. Selecting the largest prey, the euphausiids, provides an energetic advantage for E. ringens in its ecosystem where oxygen depletion imposes strong metabolic constraints on pelagic fishes. This study illustrates the plasticity of E. ringens that allows it to cope with its highly variable environment.
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