Understanding oxygen dynamics and the importance for benthic recovery in Macquarie Harbour - Progress Report

This report provides an ongoing update on the status of dissolved oxygen (DO) and benthic conditions in Macquarie Harbour. It follows on from the results previously outlined in the IMAS reports released through 2017 - 2019. These reports first described the deterioration of benthic and water column conditions in spring 2016, early signs of faunal recovery in the following autumn, when oxygen levels had improved, and the subsequent decline in benthic conditions when oxygen concentrations in middle and bottom waters returned to very low levels in spring 2017. In the January 2019 report we noted that the decline in oxygen levels in Spring 2018 wasn’t as low as observed in the previous two springs and didn’t continue for as long. Faunal abundance and diversity was less affected as a result. This report presents the results and preliminary interpretation of a repeat survey of benthic communities in June 2019 and DO monitoring data up until November 2019.