Potential Direct and Indirect Effects of Omnivorous Shrimp on Mayfly Naiads in a Tropical Island Stream: A Laboratory Study

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The goal of this project was to gain a preliminary insight into the effects of the omnivorous freshwater shrimp Xiphocaris elongata on the growth rate and resource selection of a predominant mayfly (Ephemeroptera: Leptophlebiidae). Mayfly growth was measured in laboratory microcosms in the presence and absence of shrimp using four diet treatments (Periphyton, Leaves, Periphyton + Leaves, No Resource). Growth trials lasted 5 d where mayfly pre-and post-trial body lengths were recorded. To determine the effects of Xiphocaris on resource selection, a behavioral experiment was conducted where mayflies were subject to two resource/substrate choices (Periphyton covered rocks vs. Leaves). Diel observations were performed and individuals visible on natural substrates were recorded. There were no differences in mayfly growth in the presence or absence of Xiphocaris (p = 0.16). However, growth was highest when both resources were available (Periphyton + Leaves) and there were significant differences in growth between resource treatments (p = 0.03). In behavioral trials, mayflies showed preference for periphyton covered rocks and patterns were more noticeable in the absence of the shrimp.


North American Benthological Society Annual Meeting (NABS)


Providence, RI