Pond drying cues promote cannibalism in larval Anax junius dragonflies
Persistent URL
Author(s)
Gillespie, Catherine M.
Mumme, Ronald L.
Wissinger, Scott A.
Date Issued
July 10, 2020
Abstract
Global climate change is expected to shorten hydroperiods and accelerate drying of ephemeral freshwater habitats, a shift that is likely to increase intraspecific competition and cannibalism in the aquatic animals that rely on those habitats. We experimentally examined the effects of simulated pond drying, tank size (initial larval density), and body size on survival and cannibalism in larvae of the dragonfly Anax junius, a species known to show frequent size-structured cannibalism. Thirty tanks of 3 different sizes were each stocked with 8 A. junius larvae (6 small, 1 medium, and 1 large) along with Enallagma damselfly larvae as prey. Anax junius survival and cannibalism were documented daily for 16 d. For tanks in the permanent hydroperiod treatment, we maintained water depth at a constant 14 cm for all 16 d, while we gradually reduced depth in the temporary hydroperiod tanks from 14 to 2 cm to simulate pond drying. We found that cannibalism was strongly size-dependent, as 31, 7, and 0% of small, medium, and large larvae, respectively, were cannibalized. Tank size (initial larval density) and hydroperiod treatment both affected larval survival and cannibalism. However, the effects of simulated pond drying were more pronounced than those of tank size. In addition, hydroperiod treatment was a predictor of daily risk of larval cannibalism, but daily volumetric larval density (number of A. junius alive divided by water volume present that day) was not. Our results, therefore, indicate that 1) pond drying can substantially increase cannibalism in larval odonates beyond its simple effect of producing high-density populations as water levels recede and 2) the effect of drying cues on the behavior and life-history characteristics of aquatic invertebrates merit increased attention from freshwater ecologists.
Journal
Freshwater Science
Department
Biology
Environmental Science / Studies
Citation
"Pond drying cues promote cannibalism in larval Anax junius dragonflies
Catherine M. Gillespie, Ronald L. Mumme, and Scott A. Wissinger
Freshwater Science 2020 39:3, 576-583"
Publisher
University of Chicago Press
Version of Article
Published article
Embargo
This version of the article is available for viewing to the public after July 10, 2021.
DOI
10.1086/710110
ISSN
2161-9549
2161-9565
Rights
© 2020 by The Society for Freshwater Science.
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