Effects of a total solar eclipse on invertebrate drift in Snobs Creek, Victoria

Abstract

The effect of the total solar eclipse of 23 October 1976 on invertebrate drift in Snobs Creek, Victoria, was investigated by taking hourly drift samples in two drift nets between 1300 and 2000 h (Eastern Standard Time) on 22, 23 and 24 October. Paramoera fontana (Amphipoda) and terrestrial arthropods exhibited no pattern in their occurrences in the drift. Nymphs of Baetidae (Ephemeroptera) and Trinotoperla (Plecoptera) were rarely found in the drift except after sunset, but exhibited no increase related to the eclipse. Four taxa, namely helodid (Coleoptera) larvae, the larvae of two species of Leptoceridae and one species of Conoesucus (Trichoptera), were more abundant in the drift after sunset and also exhibited an eclipse-related increase in abundance in the drift. Cricotopus (Diptera) larvae were less abundant in the drift after sunset and also exhibited an eclipse-related decrease in abundance in the drift. The results suggest that light intensity has an effect on the occurrence in the drift not only of dark-active invertebrates but also of some light-active invertebrates.