Understanding the effects of mussel aquaculture on denitrification

Report: TR 2024/17

Authors: Emily Douglas, Jenny Hillman, Drew Lohrer (NIWA)

Waikato Regional Council engaged NIWA to complete a survey and comparison of nitrogen removal rates beneath and outside mussel farms in Manaia Harbour in the Firth of Thames in late summer and spring 2023. The purpose of this work was to investigate the influence of mussel aquaculture on benthic processes to help inform spatial management. A key aim was to investigate the potential influence of mussels on the seabed that have fallen from the lines above, on ecosystem functions and services.

In collaboration with colleagues at the University of Auckland, we conducted field surveys and benthic chamber incubations beneath and outside mussel farms at two sites (inner and outer harbour) in March and November 2023.

This report presents the results of this work, including discussion and comparison with nitrogen removal rates and environmental drivers measured elsewhere