Food quality and hydropsychid caddisfly density in a lake outlet stream in Glacier National Park, Montana, USA
Valett HM and Stanford JA. 1987. Food quality and hydropsychid caddisfly density in a lake outlet stream in Glacier National Park, Montana, USA. Canadian Journal of Fisheries and Aquatic Sciences. 44(1):77-82
This article examines how changing water characteristics affect the food quality for hydropsychid caddisfly and the density of the insect's larvae. Hydropsychid caddisfly larval density averaged 6500/m2 in the lake outlet, but decreased to 1427 and 209/m2 at a distance of 200 and 3400 m downstream. Food quantity, measured as the concentration of particulate organic carbon in grab samples of seston, differed significantly between sites on only 3 of 13 sampling dates. But food quality variables (i.e. protein and ATP content of seston) were significantly higher in the lake outlet during months of higher lake productivity; monthly values of particulate protein regressed negatively with distance downstream. We concluded that stable substrate, discharge, and temperature regimes, combined with a plentiful supply of high-quality food, maintained high densities of filter-feeding hydropsychids in the lake outlet. Downstream populations were limited by comparatively greater abiotic variation (i.e. discharge, substratum, diet temperature) arid by a concomitant decrease in seston food quality.
- Type
- Journal Article
- Authors
- Valett, H; Stanford, Jack
- Units
- GLAC , WRD
- Keywords
- Animal Studies, Food Availability, Lakes & Ponds, net-spinning caddisflies (Trichoptera: Hydropsychidae), Population Density