Assessing the Impact of Suspended Sediments on New Zealand Coastal Fish: A Focus on Notolabrus celidotus and Arripis trutta

Global warming has been shown to have globally variable effects on weather. Increases in storm frequency, rainfall, and wind have the potential to increase suspended sediment concentrations in coastal oceans. Suspended sediments can have variable impacts on marine species, changing in severity for different species and age classes. Uncertainty about how suspended sediment concentrations may change and how marine species may be affected, makes this an important area of research. In New Zealand, we know very little about the effect of suspended sediment on marine species, and what is known is restricted to species of high economic value such as the New Zealand snapper, Pagrus auratus. This study aims to provide insight into the effect of suspended sediments on New Zealand coastal species. Specifically, I aim to understand the severity of the impact that suspended sediments may have on an endemic coastal fish, Notolabrus celidotus (Spotty). In addition, I also provide a guide to creating suspended sediment experiments suitable for small tomedium-sized fish, including those that require enough space to school, like Arripis trutta, (Kahawai). To do this, I firstly ran a systematic investigation of different possible experimental systems used to suspend sediment and house fish for experimentation, using Arripis trutta as my focal species. Following this, one-month long suspended sediment trials were preformed, monitoring changes in weight, body condition and gill condition in Notolabrus celidotus. The results of this study showed no statistically significant differences in weight gain or body condition to confirm detrimental effects of suspended sediment on N. celidotus. While gill histology analyses did reveal significant results, they were later rejected due to suspected processing errors. Despite this, and due to indicative trends in results, I hypothesize that N. celidotus experienced changes in its natural behaviour in response to increasing suspended sediment, and that with greater sample size and longer experimentation, results may have been statistically significant and concluded negative impacts of sediment on N. celidotus health.