摘要：The zebra mussel, Dreissena polymorpha (Pallas, 1771), invaded Lough Sheelin in the midlands of Ireland in 2001. In order to assess the status of the mussel population in the lake, the distribution, extent of colonisation, abundance, biomass and sizefrequency structure of post-settlement stages were studied in 2005 and 2006. In addition, changes to water quality parameters in the lake post-establishment were assessed with reference to the pre-invasion period. Zebra mussels were found throughout the lake at most sites on all main categories of substrates examined (stony and soft substrate; submerged vegetation: Characeae, Elodea spp., Cladophora spp., Potamogeton spp. and Myriophyllum spp., and emergent vegetation: Phragmites australis and Schoenoplectus lacustris ). Overall, increases in density and biomass of mussels were recorded from 2005 to 2006. Analysis of physiochemical data show a reduction in chlorophyll a with an increase in water transparency, however the total phosphorus concentration remains high. This paper highlights the common misconception that zebra mussel introductions lead to overall improvements in water quality.
