Photo: A plume of fine suspended sediment is discharged to the Kaipara Harbour by the Hoteo River, March 2011 (M. Pritchard, NIWA).

Cloudy, Murky, Opaque and Nutrified. A scientific project to map and better understand water quality in the Kaipara Moana.

The Kaipara Moana and its estuaries form a significant ecosystem that is a meeting place between ocean and river water, and one which is deeply connected to the surrounding land and catchment. Estuaries have a powerful filtering effect, which cleanses river water of sediments and nutrients prior to it entering the open ocean, helping ensure a thriving estuarine and marine ecosystem.

With KMR’s backing and support from the University of Auckland, Anne-Fleur van Leeuwen will begin her PhD in early 2024 on the effects of river sediment and nutrient dispersal in the Kaipara Moana, focusing on the Hōteo river mouth and Ōruawharo estuary arm.  In February, you might spot Anne-Fleur and colleagues collecting water, sediment, and zooplankton samples. These samples will be used together with existing data and satellite images to understand:
(1) where riverine nutrients and sediments go under different tidal and weather conditions, including storms,
(2) how the sediment and nutrient concentration change within the river plume and
(3) if river plume dynamics can be linked to zooplankton species and mangrove accretion.

Anne-Fleur’s research will provide new and important knowledge to better understand which areas are affected by river material and how this will change with climate change and remediation efforts.

In future, with KMR’s support, Anne-Fleur would like to present her research plans to the people of the Kaipara Moana. In the meantime, if you have any questions or comments about Anne-Fleur’s research, please email her at avan519@aucklanduni.ac.nz.

For some interesting pictures on Hōteo River see below – https://www.planet.com/stories/hoteo-river-plumes-I3_TJM4Ig