Trophic niche overlap between native bivalves and the invasive Corbicula fluminea
Conference Paper
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abstract
Freshwater native bivalves have declined in recent decades and are considered one
of the most threatened faunistic groups worldwide. Many mechanisms can be
responsible for this declining trend, being competition for resources with invasive
bivalve species one example. When in sympatry with native species, invasive
bivalves may be superior competitors regarding food acquisition due to more flexible
diets, higher abüity to find food resources or use it with higher efficiency. However,
their potential for food competition is poorly known. In this study, we aimed to
evaluate the potential overlap in resource use by bivalve species (native and
invasive) living in sympatry in the Tua basin (NW-Iberian Península), by identiíying
and quantifying the contribution of different organic matter (OM) sources to their
biomass. To accomplish this objective, the C (ÕiaC: "C/i^C) and N (Ô"N: "N/xN) stable
isotope ratios of bivalves and its potential OM sources were analyzed. Special
attention was given to the possible overlap between native bivalve species Anodonta
anatina, Unio delphinus and Potomida littoralis, and one of the most pervasive
invasive species in European aquatic ecosystems, the Asian ciam Corbicula
fluminea. The stable isotope analysis suggests that C. fluminea and P. littoralis rely
on "C- and "N- enriched sources such as microphytobenthos or other microbial
enriched material and that the potential for resource competition is high because
their trophic niche overlaps. Contrarily, the potential for competition with A. anaüna
and U. delphinus is likely lower because both native species were in general more
"C- and isN- depleted than C. fluminea indicating the consumption of more i3C- and
"N- depleted food sources such as pelagic OM.
