Seasonal stratification leads to changes within the benthic food web of the Gulf of Lions (northwestern Mediterranean) - Agropolis Access content directly
Preprints, Working Papers, ... (Preprint) Year : 2023

Seasonal stratification leads to changes within the benthic food web of the Gulf of Lions (northwestern Mediterranean)

Abstract

Like most continental shelves, the Gulf of Lions in the northwestern Mediterranean Sea provides multiple ecological services and is subject to multiple natural and anthropogenic pressures. In this context, this marine habitat must be described to monitor its evolution and ensure its protection. We used carbon and nitrogen stable isotope analysis to describe the structure of the benthic food web. Two sampling campaigns, corresponding to two contrasting situations in terms of water stratification, were carried out in 2018. One in April when the water column was still well mixed and the annual peak of phytoplankton production had already occurred, the other in September after several months of thermal stratification and low primary productivity. Results revealed that the structure of the food web changed in terms of range, extent and degree of trophic diversity. Between the two sampling dates, isotopic niches of the taxa remained evenly distributed but the niche space shrunk. Temporal changes in stable isotope compositions were greater for active suspension feeders, surface deposit feeders and their direct predators than for other functional groups feeding deep in the sediment or hunting a wider range of prey. The increase in nitrogen isotope ratios of primary consumers is either the result of a fasting effect due to reduced food availability or a change in feeding behavior due to reduced digestibility of primary food sources.
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Dates and versions

hal-03924675 , version 1 (10-01-2023)

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François Charles, Céline Labrune, François Lantoine, François Le Loc’h, Lyvia Lescure, et al.. Seasonal stratification leads to changes within the benthic food web of the Gulf of Lions (northwestern Mediterranean). 2023. ⟨hal-03924675⟩
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