Allometric Models of Simuliid Growth Rates and Their Use for Estimation of Production

Abstract

Growth rates of Prosimulium mixtum/fuscum, Stegopterna mutata, and Simulium vittatum are described in relation to individual mass, water temperature, and seston quality in the outlet of Lake Orford (southern Quebec) in the winter of 1985–86. Growth rates in mass (G, per day) of the three species were similar and inversely related to dry mass (DM, micrograms) following the power relationship G = 0.11 DM−0.28; neither water temperature nor seston abundance and quality varied sufficiently during the study period to have a significant influence on growth rates. The allometric model was used to estimate production of the three species, and the resulting estimates are compared with cohort methods and size–frequency estimates. Large larvae were responsible for most of the production, and most of the production occurred before the spring rise in water temperature. Measured growth rates in winter are significantly lower than those reported for simuliids in warmer waters. A reanalysis of published data shows that growth rates of simuliids increase as the square root of water temperature (T, degrees Celsius) (G = 0.08 DM−0.21 T0.48).