Prey use of wetland benthivorous sunfishes ontoge

Authors: Jacob W Bransky Nathan J Dorn

Publish Date: 2013/02/12

Volume: 96, Issue: 12, Pages: 1329-1340

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Abstract

The intensity of competitive interactions between fishes is partly determined by prey use and ontogenetic niche shifts In a wetland where distinct habitat shifts are missing we compared prey use of three generalist benthivorous sunfishes to look for evidence of ontogenetic interspecific and “seasonal” variation in prey composition Diet analysis revealed evidence of diet ontogeny in warmouth Lepomis gulosus 30–152 mm standard length SL but not in bluespotted sunfish Enneacanthus gloriosus 30–47 mm SL or dollar sunfish Lepomis marginatus 30–60 mm SL Bluespotted and dollar sunfishes consumed small dipteran and amphipod prey and had similar diets in both seasons suggesting a potential for strong interspecific competition In the dry season warmouth shifted from using smaller insect prey to larger decapod and fish prey with increasing size This shift to prey types that were little used by the other species reduced dietary niche overlap with the other sunfishes After drought and reflooding in the wet season decapods and small fish were less abundant in the wetland and the warmouth ontogenetic shift was less distinct When matched for gape width prey composition differed between warmouth and both dollar and bluespotted sunfishes in the wet season suggesting differences in sunfish foraging modes but prey use differences were less clear in the dry season when prey were abundant Both warmouth ontogenetic diet shifts and seasonal variation in prey use probably mediated by prey abundance had strong influences on diet overlap and therefore the potential for intra and interspecific competition between sunfishes in this wetland ecosystemWe thank N Knorp R Boyle C van der Heiden M Kobza M Crider and J Johnson for help with fieldwork Three anonymous reviewers improved this manuscript We would also like to thank E Cline and the South Florida Water Management District for the use of the experimental macrocosms at LILA and various forms of sampling gear Research protocols were approved by the Florida Atlantic University Institutional Animal Care and Use Committee

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