Insights into Monitoring Turbidity and Nutrient Dynamics in a Large Mesotidal Estuary

Abstract With the increase of climate change and local stressors on estuarine ecosystem health, there is an increased interest and demand for better understanding of estuarine physical and biogeochemical processes. New Zealand estuaries experience a high sediment input and are often undersampled. The large fine re-suspendable sediment pool is expected to interact with nutrients within the water column and therefore the Estuary Turbidity Maximum (ETM) is expected to play a large role in estuarine biogeochemical processes. Here we present our experience in setting up a measurement scheme in a large, shallow, mesotidal and undersampled estuary. We monitor turbidity, salinity, and nutrients both via transects and deployments. This provides a spatial and temporal snapshot of general trends and relevant processes within an estuary tributary. In addition, this method allowed the localization of the ETM and subdivision of the tributary into zones to assist in future sample site selection and post-processing.