Diversity and seasonality of adult caddisflies (Trichoptera) captured by light-trapping beside streams in the Darwin region of northern Australia

Abstract

Caddisflies comprise a major component of the macroinvertebrate diversity of streams throughout the world. We studied temporal variation in the abundance and diversity of caddisflies of six streams in the monsoonal wet-dry tropics of northern Australia. Abundance and diversity of adult caddisflies were highly seasonal with most activity within wet season months from January to April, with a synchronous pulse of activity in the mid-dry season in two of the three years of study at some sites. Modelling of species richness showed variability among sites in the seasonal patterns of species richness. Multivariate analysis identified seasonal change in assemblage composition. These results are relevant to the design of biodiversity studies on seasonally flowing streams. Surveys of caddisfly diversity are most effectively undertaken during and after the wet season: repeated surveys are required to maximise the detection of the full suite of species occurring at a site.