The effects of velocity and discharge on the size, morphology, and density of nets spun by Ceratopsyche sparna.

Abstract

The effects of flow and discharge on net construction of caddisfly larvae were examined. Nets spun by hydropsychid caddisfly larvae (Ceratopsyche sparna) were measured in eight model streams varying in current velocity (high-low) and total discharge (1000-200 cm3/s). Measurement of net width, depth, and density were recorded and net area and shape were calculated. We found no significance between velocity and : net density (t=0, def=6, p=1), net area (t=-0.35, df=6, p=0.74), or length:width ratio (t=0.97, df=6, p=0.37). There was no significance between discharge: and density (F=0.17, df=3, p=0.91), net area (F=1.52, df=3, p=0.34), or length:width ratio (F=0.33, df=3, p=0.81). Our observations were made in spite of several studies which have shown otherwise.