Life history and production of a semi-terrestrial limnephilid caddisfly in an intermittent Platte River wetland

Abstract

The life history and ecosystem significance of a recently discovered species of Ironoquia (Trichoptera:Limnephilidae) were examined in a riparian slough of the central Platte River, Nebraska, USA. Monthly benthic samples were collected for 1 y and adult emergence was monitored to examine I. plattensis life history in this harsh, intermittent habitat. Ecosystem significance of this caddisfly was assessed by estimating larval secondary production and consumption of coarse particulate organic matter (CPOM), biomass exported from the slough during larval migration onto land, and adult emergence production from the riparian prairie where pupation occurred. The life cycle of I. plattensis appeared intimately linked to the hydroperiod, with larval migration to land and adult emergence coinciding with drying and inundation of the slough, respectively. Total larval production in a 20-m reach of slough, adjusted for average wetted area during sampling intervals, was 429-536 g ash-free dry mass (AFDM)/y, depending upon the method of calculation. Biomass that left the slough via larval migration to land was estimated at 109 g AFDM (~O23% of larval production), and total adult emergence was 69 g AFDM (~16% of larval production). Turnover rate of larval biomass was 1012/y. CPOM consumption estimates indicated that larvae in the study site consumed 8690 g AFDM/y, ~13% of the annual average CPOM standing stock in the site. Results demonstrate that this leaf-shredding trichopteran is a productive component of this prairie wetland system, representing an abundant invertebrate food resource for aquatic and terrestrial predators and facilitating decomposition processes. However, its distribution along the central Platte River may be limited because of habitat destruction and its adaptation to a specific hydrologic regime.