[en] Echinoids are common members of Antarctic zoobenthos, and different groups can
show important trophic diversity. As part of the ANT-XXIX/3 cruise of RV Polarstern,
trophic plasticity of sea urchins was studied in three neighbouring regions (Drake
Passage, Bransfield Strait and Weddell Sea) featuring several depth-related habitats
offering different trophic environments to benthic consumers. Three families with
contrasting feeding habits (Cidaridae, Echinidae and Schizasteridae) were studied. Gut
content examination and stable isotopes ratios of C and N suggest that each of the
studied families showed a different response to variation in environmental and food
conditions. Schizasteridae trophic plasticity was low, and these sea urchins were bulk
sediment feeders relying on sediment-associated organic matter in all regions and/or
depth-related habitats. Cidaridae consumed the most animal-derived material. Their
diet varied according to the considered area, as sea urchins from Bransfield Strait
relied mostly on living and/or dead animal material, while specimens from Weddell Sea
fed on a mixture of dead animal material and other detritus. Echinidae also showed
important trophic plasticity. They fed on various detrital items in Bransfield Strait, and
selectivity of ingested material varied across depth-related habitats. In Weddell Sea,
stable isotopes revealed that they mostly relied on highly 13C-enriched food items,
presumably microbially-reworked benthic detritus. The differences in adaptive
strategies could lead to family-specific responses of Antarctic echinoids to
environmental and food-related changes.
Research Center/Unit :
MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
