Biological and physical parameters of water quality in the Mulloon Creek catchment, NSW
Macroinvertebrates of freshwater can serve as an indicator of water quality as well as the changes that occur to water over a season. The types of macroinvertebrates are considered to vary in water as a result of differences in the groups that are present with regards to their ability to cope with the differing physical parameters of the water in which they dwell. The major physical changes in water are those that can affect the life cycle of the invertebrates, as well as their ability to survive over the short term. Normally, the physical aspects that are measured are the water temperature, as that determines the rate of growth of the invertebrates, but also influences the oxygen that can be dissolved in the water.
In this report, ANU present information regarding the macroinvertebrate communities that are present at six sites along Mulloon Creek over 9 months (October 2015-May 2106) along with the physical conditions that were present along the stream at that time. ANU examine how the physical parameters may influence the composition of invertebrates at the various locations as well as how stable the communities are over the period of measurement. This study will be a baseline for understanding how future work and development along Mulloon Creek may affect the various macroinvertebrate communities.
Overall, 3439 macroinvertebrates were identified, falling into 60 different taxa (see Appendix 2 for complete list). The largest number of invertebrates was collected in January, although the pattern differed somewhat among the sites. The number of taxa tended to increase as number of individuals increased, but that was dependent upon site. Peter’s Pond was the source of the highest number of individuals collected (January) and the most taxa collected (April). Sandhills Creek had the fewest number of individuals collected over the study period, and was generally depauperate.
To assess how the macroinvertebrate collections indicated the state of the various sites, two different methods for comparing the sites were undertaken, SIGNAL and PCA. The first method was the calculation of SIGNAL scores, and compared to previous study in 2006-08 at Mulloon Creek Natural Farms pilot project area. The principal component analysis (PCA) gives a slightly different picture of the sites compared with the SIGNAL analysis. Sites of similar physiochemical properties tended to have similar results, and highly related to seasonal changes in temperature and flow rates. Additionally, PCA analysis indicated differences in biological macroinvertebrate assemblages. The full results showed how these relationships and trends over the seasons reflected species diversity and numbers.
Image - Calamoceratidae (Trichoptera), courtesy of ANU.