Dynamique des populations larvaires et régime alimentairede Rhyacophila tristis Pictet (Trichoptera: Rhyacophilidae)dans un ruisseau de haute montagne

Abstract

Rhyacophila tristis Pictet has been studied for three consecutive years in a Pyrenean river (altitude 1930 m, maximum temperature 17° C in August, snow cover 4-6 months per year).The larvae are essentially carnivores, feeding chiefly on chironomids. Larval development takes two years. Growth occurs chiefly in the period when there is no snow. Between the first and second winter of larval life, the growth rate (in terms of dry weight) has a mean value of 2.25 % day-1. During this period, the population loss-rate has a mean value of 1.6 % day-1. Instantaneous rates of growth and mortality remain similar from one generation to the next. Production has been estimated at 240 mg m-2 year-1 (meen annual production to biomass ratio = 3.1). © Masson, 1984.