Trophic resources of the bivalve,Venus verrucosa, in the Chausey archipelago (Normandy, France) determined by stable isotopes and fatty acids

Abstract

-In the Chausey archipelago, growth of the burrowing bivalve Venus verrucosa (Mollusca: Veneridae) has been shown to be highly variable between closely located sites (<1 km). To explain this small-scale spatial variability, we tested the trophic hypothesis using both fatty acid markers, and carbon and nitrogen stable isotopes (δ 13 C and δ 15 N). Environmental parameters, including substrate, were also analysed to discriminate their effects on potential trophic differences. Results of isotopic fractionation and lipid profiles of water column and digestive gland samples both showed a large contribution of phytoplankton to the diet of V. verrucosa. More surprisingly, the same results suggest that Phaeophyceae and Rhodophyceae macroalgae could contribute to the nutrition of V. verrucosa as dissolved exudates. Whereas site differences were not observed between the food sources of V. verrucosa, we showed that growth performance index was correlated to wave height. Thus, we hypothesized that the high local growth variability could be controlled by the hydrosedimentary dynamics. In addition, although no significant growth differences were found between intertidal and subtidal populations, better condition index and more total lipids were found in the digestive gland of intertidal V. verrucosa, suggesting potential compensatory growth mechanisms.

Spatial and temporal dynamics of nano‐ and pico‐size particulate organic matter (POM) in a coastal megatidal marine system

“…Lower concentrations of PUFA-rich picoeukaryotes may explain the lesser trophic resource potential of this site. Results may also be related to large wave amplitude, which has been suggested to cause relatively slower bivalve growth (Perez et al 2013).…”

“…In the English Channel, seasonal phytoplankton dynamics are well documented; smaller phytoplankton are abundant year‐round (Not et al ; Widdicombe et al ) and contribute significantly to algal biomass and primary production (Not et al ; Widdicombe et al ; Masquelier et al ), while larger sized phytoplankton (e.g., diatoms, dinoflagellates) have intense and ephemeral seasonal blooms (Irigoien et al ; Henson et al ; Van Oostende et al ). While these previous works underline seasonal patterns of nano‐ and picoplankton in this region, there is a paucity of information on POM dynamics in this size range, particularly in regions with tight benthic‐pelagic coupling, such as the western English Channel, where POM is strongly influenced by both living and nonliving phytoplankton and macroalgae (Perez et al ).…”

Trace element fingerprinting of cockle (Cerastoderma edule) shells can reveal harvesting location in adjacent areas

“…Most studies have relied on molecular techniques, including PCR1112, FINS1314 and DNA barcoding1516, for species identification. Molecular tools, particularly microsatellites1718, as well as biochemical methods, such as fatty acids192021 and stable isotopes212223, have also been used to assess geographical origin of bivalves. Trace element fingerprinting (TEF) of bivalve mineral structures may also be useful to distinguish populations or stocks242526.…”

Trophic niche partitioning of dominant North‐Atlantic krill species, Meganyctiphanes norvegica, Thysanoessa inermis, and T. raschii

“…FATM were divided into three groups: (i) markers for phytoplankton, 20:5n3 for diatoms (eicosapentaenoic acid [EPA]; Dalsgaard et al ) and 22:6n3 for dinoflagellates (docosahexaenoic acid [DHA]; Kharlamenko et al ); (ii) macrophytes and terrestrial matter classically marked by the long‐chain saturate FAs (Perez et al ), 18:3n3 and 18:2n6 (Budge and Parrish ); and (iii) markers for copepods with the sum of 20:1 and 22:1 isomers (n11, n9, n7, and n5) for calanoid copepods (e.g., dominant in Calanus spp. ; Lee ; Fraser et al ) and 18:1n9 for Pseudocalanus spp.…”