Author: Holly A Wellard Kelly,  Researcher (University of Minnesota Duluth)

Description:
Small nearshore fish compose an important part of lacustrine biodiversity and functional diversity and link pelagic and benthic habitats by serving as prey to larger nearshore and offshore fish. However, the trophic complexity of these small nearshore fish is often unrecognized and detailed studies of their food webs are often lacking or focus on larger predator or game fish. Here, we examined niche space patterns of small nearshore fish species using Bayesian analyses of carbon and nitrogen stable isotope data in nine Minnesota inland lakes. We found considerable intraspecific variability in fish niche areas and niche overlap across species. At the assemblage level, there is less niche overlap (average diet overlap of all species pairs at a lake) as whole-lake species richness increases, possibly indicating a greater degree of resource specialization in more speciose lakes. Overall fish niche space was weakly, but significantly, related to niche space of their invertebrate prey. Although littoral benthic resources contributed to fish diets in all lakes, all fish species also had non-negligible and variable contributions from pelagic zooplankton. We concluded that there was generally high inter- and intraspecific variability in niche space of nearshore fishes. Multi-level trophic complexity in these lakes may be important for functional diversity and resilience to ecosystem changes that may alter basal resources and intra- and interspecific interactions.

Category: Scientific Program Abstract > Special Session > CS23 Aquatic food webs