@article {7215, title = {Trophic niche of the invasive gregarious species Crepidula fornicata, in relation to ontogenic changes}, journal = {bioRxiv}, year = {2021}, pages = {2020.07.30.229021}, type = {ver. 4 peer-reviewed and recommended by Peer Community In Ecology}, abstract = {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) suggest 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 showed well discriminated compositions over the studied 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. Over the studied 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. However, 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). 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 from ontogenic physiological changes (differential growth rates, metabolic rate or gametogenesis) rather than diet discrepancies. This study revealed that multiple trophic markers allow high complementary to characterize organic matter as well as food partitioning between conspecific organisms.
Recommended by PCI Ecology : https://ecology.peercommunityin.org/articles/rec?id=140}, doi = {10.1101/2020.07.30.229021}, url = {https://www.biorxiv.org/content/10.1101/2020.07.30.229021v1.abstract}, author = {Androuin, Thibault and Stanislas Dubois and C{\'e}dric Hubas and Lefebvre, Gwendoline and Le Grand, Fabienne and Gauthier Schaal and Carlier, Antoine} } @article {5176, title = {Interplay between abiotic factors and species assemblages mediated by the ecosystem engineer Sabellaria alveolata (Annelida: Polychaeta)}, journal = {Estuarine, Coastal and Shelf Science}, volume = {200}, year = {2018}, abstract = {

Sabellaria alveolata is a gregarious polychaete that uses sand particles to build three-dimensional structures known as reefs, fixed atop rocks or built on soft sediments. These structures are known to modify the local grain-size distribution and to host a highly diversified macrofauna, altered when the reef undergoes disturbances.
The goal of this study was to investigate the different sedimentary and biological changes associated with the presence of a S. alveolata reef over two contrasting seasons (late winter and late summer), and how these changes were linked. Three different sediments were considered: the engineered sediment (the actual reef), the associated sediment (the soft sediment surrounding the reef structures) and a control soft sediment (i.e. no reef structures in close proximity). Univariate and multivariate comparisons of grain-size distribution, soft sediment characteristics (organic matter content, chlorophyll a, pheopigments and carbohydrate concentrations) and macrofauna were conducted between the different sediment types at both seasons and between the two seasons for each sediment type. A distance-based redundancy analyses (dbRDA) was used to investigate the link between the different environmental parameters and the macrofauna assemblages. Finally, we focused on a disturbance continuum of the engineered sediments proxied by an increase in the mud present in these sediments. The effects of a continuous and increasing disturbance on the associated fauna were investigated using pairwise beta diversity indices (S{\o}rensen and Bray-Curtis dissimilarities and their decomposition into turnover and nestedness). Results showed a significant effect of the reef on the local sediment distribution (coarser sediments compared to the control) and on the benthic primary production (higher in the associated sediments). At both seasons, S. alveolata biomass and sediment principal mode were the environmental parameters which best differentiated the engineered, associated and control sediment assemblages. These two parameters are under the ecosystem engineer{\textquoteright}s influence stressing its importance in structuring benthic macrofauna. Furthermore, in late summer but not in late winter, presence/absence and abundance based beta diversity were positively correlated to our disturbance proxy (mud content) a tendency driven by a species replacement and a rise in the associated fauna density.
Our first set of results highlight the importance of S. alveolata reefs as benthic primary production enhancers via their physical structure and their biological activity. The results obtained using beta diversity indices emphasize the importance of recruitment in structuring the reef{\textquoteright}s macrofauna and {\textendash} paradoxically {\textendash} the ecological value of S. alveolata degraded forms as biodiversity and recruitment promoters.

}, doi = {doi.org/10.1016/j.ecss.2017.10.001}, url = {https://doi.org/10.1016/j.ecss.2017.10.001}, author = {Auriane Jones and Stanislas Dubois and Nicolas Desroy and J{\'e}r{\^o}me Fournier} } @article {5611, title = {Marine sublittoral benthos fails to track temperature in response to climate change in a biogeographical transition zone}, journal = {ICES Journal of Marine Science}, year = {2018}, abstract = {

Species ranges are shifting globally to track temperature changes in response to climate warming, with substantial variability among taxa. In
the English Channel, a biogeographical transition zone between the cold temperate and warm temperate provinces of the North-East Atlantic, distribution shifts have been relatively well documented for plankton, fish and intertidal benthic organisms, but little information is available on sublittoral benthos. Following a description of the magnitude of the sea bottom temperature (SBT) rise, the changes in the distribution and occupancy of 65 benthic invertebrate species were analysed by comparing data collected throughout the English Channel at more
than 200 stations sampled during a cool period in the 1960s{\textendash}1970s and at present in 2012{\textendash}2014. A non-uniform rise in SBT for the last three
decades was observed at the regional scale, varying from 0.07 to 0.54C per decade. This rise differs from that reported for sea surface temperature
(SST) in stratified areas suggesting that SBT should be used rather than SST to analyse responses of subtidal organisms to climate change. Despite shifts in both minimum and maximum sea bottom isotherms (2.5 and 3.2 km.year1, respectively), the distribution centroid shift of most species remained \<1.0 km.year1, regardless of the average temperatures they usually experience. Conversely, decreases were observed in the occurrence of most cold-water species and increases were found in the occurrence of most warm-water species. These results suggest that ongoing climate change could lead to a decrease in benthic biodiversity at range limits, especially where connection routes are lacking for new migrants.

}, doi = {doi:10.1093/icesjms/fsy095}, author = {Fran{\c c}ois Gaudin and Nicolas Desroy and Stanislas Dubois and Caroline Broudin and Louis Cabioch and J{\'e}r{\^o}me Fournier and Franck Gentil and Jacques Grall and C{\'e}line Houbin and Patrick Le Mao and Eric Thi{\'e}baut} }