Experimental tests of eggs-tinction! Shortages of adults or egg-laying habitat cause oviposition failure for aquatic insects in dammed and undammed rivers.

Abstract

For organisms with complex life cycles, shortages of females or egg-laying (oviposition) habitat can limit egg densities, recruitment of offspring and abundances of later life stages. Hence, the determinants of oviposition success may be critical for understanding how human activity impacts stream ecosystems. Many aquatic insects require clean, emergent rocks that project from streams as places to land and lay eggs. In undammed rivers, high nutrient loads and low summer flows can result in dense growths of algae on rocks (algal encrustment) which may inhibit oviposition. Downstream of dams, water impoundment may intensify algal encrustment or strand rocks above the waterline, potentially lim..