Pearson, R. (2009). Foraminifera of the Avon-Heathcote Estuary. University of Canterbury.

Prepared in 2009 for Environment Canterbury and the Avon-Heathcote Estuary Ihutai Trust as part of the University of Canterbury Summer Scholarship Programme, this report aimed to systematically map the distribution and species diversity of Foraminifera in the Ihutai estuary in relation to environmental variables. This created a baseline dataset which could be used to identify future changes or map natural developments and anthropogenic influences in the estuary over time.

Foraminifera are small protozoans that form species assemblages in marine and brackish surface sediments. Their distribution can be an important environmental indicator as they are common in Aotearoa New Zealand estuaries and respond to environmental variables such as water depth, tidal exposure, salinity, temperature, organic matter content, sediment characteristics, water chemistry, and oxygen supply. Overall, this study took grain size and foraminifera samples from twenty-six locations in the Ihutai estuary. Results revealed a low foraminifera abundance and species diversity across the estuary, and high proportions of juveniles. The researcher suggested that the low abundance of tests (shells) found may have been caused by poor preservation conditions, however, the high juvenile proportions likely indicated that foraminifera were not surviving to maturity in Te Ihutai. The report suggested that the low species diversity was likely caused by several environmental factors, including pollution, sediment input changes, eutrophication, and algal blooms. Consequently, it was concluded that further investigation was required to fully assess possible contaminants and causes of foraminiferal distribution in Te Ihutai.