| dc.description.abstract | Pond permanence is thought to be the single most important abiotic factor influencing insect community structure in small ponds. In permanent ponds (ponds that hold water for years at a time) containing fish, fish act as size selective predators, reducing the number of large insect taxa, such as dragonflies. In semi-permanent ponds (ponds that dry periodically), the absence of fish allows for an increase in abundance of large-bodied, predatory insects, e.g. dragonflies, which replace fish as the top predators in the system. Although it is well established that insect communities are different in permanent and semi-permanent ponds because of fish predation, little is known about aquatic insect succession and emergence in human made semi-permanent ponds after it has dried and then refills. The objective of this study was to examine insect emergence in small, human-made permanent ponds that continuously hold water and in human-made semi-permanent ponds that were dried and refilled with water. We conducted the present study in six human-made farm ponds at LBJ Grasslands, North Texas. Emergent insects were collected for one week, June 15 - 22, 2018 for all six ponds to assess the impact of pond permanence on emergence. Two pyramid-shaped floating emergence traps were used per pond to sample adult emerging insects. The traps funneled emerging insects into a collecting bottle containing 95% ethanol. All individual insects collected from a given pond were identified and counted. Eight taxonomic groups of insects were captured in adequate numbers for analyses; Diptera: Chironomidae: Chironominae and Orthocladiinae (primarily herbivorous chironomids), Diptera: Chironomidae: Tanypodinae (predatory chironomids), Diptera: Chaoboridae (phantom midges), Trichoptera: Hydroptilidae (micro-caddisflies), Ephemeroptera: Baetidae (mayflies), Odonata: Zygoptera (damselflies) and Anisoptera (dragonflies). There was a greater average emergent insect abundance from semi-permanent ponds than permanent ponds for all taxa although only the emergence of Odonates was statistically different between pond types. Pond permanence and the presence of fish affects insect emergence from human made ponds. | |
