Aquatic fauna and water quality at Lake Chandala
Tuesday, 01 December 2009
Found between Muchea and Gingin, on the Swan Coastal Plain north-east of Joondalup, Lake Chandala is listed on the Directory of Nationally Important Wetlands. Lake Chandala is an important site for several wetland bird species, and as one of a limited number of wetlands with darkly stained waters remaining on the Swan Coastal Plain (SCP), is of regional significance too. The wetland consists of a permanent lake, which over winter and spring expands to inundate the surrounding melaleuca and eucalypt woodlands. In Spring 2009 surveys of water quality and fauna were examined at Lake Chandala. Funding was provided by Tiwest in partnership with the Department of Environment and Conservation’s (Department of Environment and Conservation) nature conservation program in the Perth Hills District, and the project taken up by ECU with surveys carried out as a third-year student research project by Neisha McLure, with Pierre Horwitz and the Department of Environment and Conservation’s Robert Huston. Results from water testing indicate elevated nitrogen and phosphorus levels at Lake Chandala. While the levels present would usually be expected to be accompanied by very high primary productivity, often associated with algae blooms, at the time of testing chlorophyll 'a' levels (used as an indicator for primary productivity) were lower than expected. This trend has been noted in other coloured wetlands on the SCP, with the colour and properties of the tannin rich waters linked to reduced light, highlighting the importance of maintaining vegetation around the margins of wetlands. Surveys also showed the wetland supports a relatively diverse assemblage of aquatic invertebrates and a high proportion of regionally endemic species. Species composition variedsignificantly between sites, reflecting the different habitats, water quality and water permanence across the wetland. The shield shrimp Lepidurus apus, a species not previously recorded on the SCP was also found during surveys. Some of the other exciting finds during surveys of Lake Chandala include the discovery of two freshwater fish, Bostockia porosa and the restricted and threatened Galaxiella nigrostriata (Black-striped minnow), and a fresh water sponge. Results of water testing also appear to back up the belief that the northern part of the wetland contains permanent water, possibly fed by spring. A trip to the lake is planned for this summer to investigate further.