Meeting Abstract

P1.35  Saturday, Jan. 4 15:30  Feeding preferences of a freshwater amphipod for aquatic vascular plants and macroalgae SCRIBER, KE; MCCLINTOCK, JB*; AMSLER, CD; Univ. of Alabama at Birmingham; Univ. of Alabama at Birmingham; Univ. of Alabama at Birmingham mcclinto@uab.edu

Many factors influence the palatability and feeding preferences of predators for their prey. The present study tested the null hypothesis that the common freshwater amphipod Hyallela azteca presented three species of vascular plants and two species of filamentous algae displayed feeding rates indicative of no differences in prey palatability. Differences in prey palatability were found and pairwise-choice feeding assays were conducted and preferences for particular foods established. Subsequent feeding bioassays using standard techniques demonstrated that tissues of the vascular plant Vallisneria americana were chemically defended against amphipod grazing, and that extracts from this vascular plant could inhibit feeding by amphipods on other species of vascular plants and algae. Tissue toughness, measured by penetrometry, indicated all three vascular plants likely rely on structural defense. There was no correlation between nutritional value (protein content) and prey palatability or preference for a given prey. The findings of this study emphasize the importance of the direct contribution of vascular plants and algae to freshwater food chains, an important topic in freshwater benthic ecology that has been largely overlooked.