MACROINVERTEBRATE STREAM DRIFT – AN AUSTRALIAN EXAMPLE

Abstract

The flow of organisms in lotic environments is known as Macroinvertebrate Stream Drift: a phenomenon that has long fascinated freshwater ecologists. Stream-dwelling organisms are often transported downstream in the water column in substantial numbers. Because they have limited swimming ability and the movement is apparently passive, the process is referred to as drift. This study assesses drift fauna in a lotic environment upstream from the Australian inland city of Wagga Wagga, looking at the abundance and diversity of invertebrates over sampling times spanning daytime, dusk and nighttime. Not only did the abundance of individual macroinvertebrates increase from daytime to nighttime, but the diversity of taxa also increased. Although not as sharp as the increase in individual numbers, the diversity of taxa however did more than double from the dusk sampling period to the first night sampling period.