Odonate Predation on Cyprinodon nevadensis shoshone

Authors: Bridger Scraper, Sekhar A., Brian Wisenden, Craig Stockwell

Year: 2024

Abstract

We investigated the population-level effects of dragonfly nymph, Anax junius, presence on Shoshone pupfish, Cyprinodon nevadensis shoshone, in an ex-situ mesocosm experiment. Experimental mesocosms were established in twenty 1136-L stock tanks at the North Dakota State University (NDSU) North Dakota Agricultural Experiment Station (NDSU IACUC #A18054). Each mesocosm was outfitted with river rock substrate, artificial structures (FisHiding®), aeration, and screened covers to block birds and adult odonates. Tanks were stocked with six adult Shoshone pupfish (four females, two males) drawn randomly from a holding tank, and arranged linearly in experimental blocks. Mesocosms were randomly assigned to one of two treatments: pupfish in allopatry (control) or sympatry with 30 dragonfly nymphs (dragonfly treatment). After 6 wk, tanks were drained, and surviving dragonfly nymphs, pupfish larvae, and adult pupfish were counted. Shoshone pupfish juvenile production was higher by a factor of 2.8 times for control mesocosms (265.9 ± 54.63; mean ± SE) compared to mesocosms with dragonfly nymphs (94.5 ± 35.09). These data show that dragonflies may be an important predator on small-bodied fish and thus may select for anti-predator traits.