Habitat distribution, dietary composition and life history characteristics of odonate nymphs in a blackwater coastal plain stream

摘要

The ecology and life histories of odonates were studied in a headwater, sand-bottomed coastal plain stream in Virginia. Quantitative sampling of odonates in sand and silt sediments, on submerged snags and in debris dams was conducted monthly for 13 mo. Six species of odonates were common in the stream. Calopteryx maculata (Calopterygidae) had a univoltine life history, whereas Boyeria vinosa (Aeshnidae) Cordulegaster maculates (Cordulegastridae), Gomphus cavillaris, Hagenius brevistylus and Progomphus obscurus (Gomphidae) were semivoltine. The odonates were most abundant in debris dams, less abundant in silt and sand sediments and least abundant on snags. Habitat-specific production of odonates was 1.3 g m(-2) y(-1) in debris dams and 0.1 - 0.3 g m(-2) y(-1) in the sand, silt and snag habitats. The production to biomass ratio (P/B) for Calopteryx was 5.9, whereas ratios for semivoltine species ranged from 2.0 - 4.0.