Trophic niche of the invasive gregarious species Crepidula fornicata , in relation to ontogenic changes

Type Article
Date 2020-01
Language English
Author(s) Androuin ThibaultORCID1, 2, Dubois StanislasORCID2, Hubas CédricORCID3, Lefebvre Gwendoline4, Le Grand Fabienne4, Schaal GauthierORCID4, Carlier AntoineORCID2
Affiliation(s) 1 : ISMER, UQAR, Rimouski, Canada
2 : IFREMER, DYNECO-LEBCO, Technopole Brest-Iroise, CS10070, Plouzané, France
3 : UMR BOREA, Muséum National d’Histoire Naturelle, Concarneau, France
4 : UMR CNRS 6539, LEMAR-IUEM-UBO, Plouzané, France
Source BioRxiv (Cold Spring Harbor Laboratory), 2020-01 , P. Version 4 (35p.)
DOI 10.1101/2020.07.30.229021
Note This is a preprint. It has not been certified by a journal but peer reviews are available
Keyword(s) Crepidula fornicata, trophic niche, ontogenic shift, fatty acids, stable isotopes, pigments, Bay of Brest

The slipper limpet Crepidula fornicata is a common and widespread invasive gregarious species along the European coast. Among its life-history traits, well documented ontogenic changes in behavior (i.e., motile male to sessile female) suggests a potential shift in feeding strategy across its life stages. Considering the ecological significance of this species in colonized areas, understanding how conspecifics share the trophic resource is crucial. Using fatty acids (FA) and stable isotopes (SI) as complementary trophic markers, we conducted a field survey between late winter and spring to investigate the trophic niche of three ontogenic stages of C. fornicata that bear different sexual (male/female) and motility (motile/sessile) traits. Potential trophic sources were characterized by their pigment, FA and SI compositions and discriminated well over the study period. We showed that the biofilm covering C. fornicata shells harbored a higher biomass of primary producers (i.e., chlorophytes and diatoms) than the surrounding sediment surface. Over the study period, we observed a covariation between the three ontogenic stages for both FA and SI compositions which suggest that the trophic niche of C. fornicata does not change significantly across its benthic life. During periods of low food availability, slipper limpets displayed an opportunistic suspension-feeding behaviour, relying on both fresh and detrital organic matter, likely coming from superficial sedimentary organic matter. During high food availability (i.e., spring phytoplankton bloom), all ontogenic stages largely benefited from this fresh supply of organic matter (pelagic diatoms in this case). However, the three ontogenic stages showed consistent differences in FA composition, and to a lesser extent in SI composition. These differences persist over time, as they originate more likely from ontogenic physiological changes (e.g., differential growth rates, metabolic rate or gametogenesis) rather than diet discrepancies.

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