A rapid assessment method for an invasive mollusc in an Irish lake

Abstract

A rapid assessment method to evaluate the relative impact of zebra mussel, Dreissena polymorpha, was undertaken in a 11.5 km2 temperate lake within an Irish drumlin landscape. The lake was divided into three assessment units: the north lake, the south lake and a river section situated downstream of the two lake assessment units. Survey work was conducted as a single survey in September 2011. Following an evaluation of the mussel abundance and distribution range within each assessment unit, the Biological Pollution Level (BPL) was calculated. Additional environmental information was obtained from historical monitoring conducted by the Irish Environmental Protection Agency. The zebra mussel was rated as having a high abundance and distribution range in one lake assessment unit, was absent in the second lake assessment unit, and had a low abundance and distribution range for the river assessment unit. Ninety-three stations were surveyed in two and a half days illustrating a practical approach to monitoring which can meet legislative requirements.