Is biomonitoring really effective?

The purpose of freshwater biomonitoring is to provide an indication of a stream’s, river’s, or lake’s health, typically in order to make a connection between a human activity and resulting effects. CPG has been undertaking biomonitoring annually within the Waitangi Stream since 2001 to assess possible impacts of landfill leachate and wastewater discharge originating from the Waiouru Military Camp and settlement. This paper discusses preliminary results from analysis of a seven-year longitudinal biomonitoring study to assess the impacts to Waitangi Stream from these discharge activities. Data was analysed using two approaches including one which examines variations and differences in each individual quantity measured and one which instead analyses the entire data set at once using principal components analysis (PCA). The two approaches provide different perspectives, however with consistent outcomes. As expected, the integrated approach (PCA) provided a broader perspective on the factors most influential in description of site disposition. Landfill control and impact sites were clearly differentiable in terms of habitat, but this did not manifest in large differences in macroinvertebrate health, whereas wastewater control and impact sites were not greatly different in terms of habitat, but the impact site did show evidence of compromised macroinvertebrate health. In conclusion, despite the inherent variability of biological data, biomonitoring is effective in understanding the inter-yearly variability between control versus impacted sites. The approach described herein, and related approaches, will help ensure that biomonitoring can be used to maximum utility.