The potential for inferring trophic state of Lake Wairarapa using zooplankton community composition

Abstract

The use of biotic responses to infer lake trophic state (i.e., the bioindicator approach) is commonly neglected in favour of chemical and physical methods. Duggan et al. (2001a, 2001b, 2002) found that trophic state was the main determinant of rotifer distribution among North Island, New Zealand, lakes. Based on these responses developed a quantitative bioindicator index, using rotifer community composition, to infer Trophic Lake Index (TLI) values (sensu Burns et al. 1999). This approach was recently used successfully to infer trophic state changs in lakes of the Auckland region (Duggan & Barnes 2006). In this report I evaluate whether Lake Wairarapa would be a suitable candidate for monitoring trophic state using zooplankton during Wellington Regional Council's regular quarterly sampling, and what the number of net samples would be required during monitoring (i.e.., to collect greater than 300 individual zooplankton).