Latest progress report on research into Macquarie Harbour environmental conditions

IMAS researchers today released the latest results of surveys of environmental conditions in Macquarie Harbour, carried out as part of a research project studying oxygen dynamics and conditions on the bottom of the harbour.

The report presents the results and preliminary interpretation of dissolved oxygen (DO) monitoring data up until the beginning of January 2018 and a repeat survey of benthic communities in October 2017.

IMAS Research Fellow Dr Jeff Ross said regular updates are being provided on the project, which is designed to inform the long-term sustainable management of the harbour.

“Our surveys in October 2017 found that oxygen levels in Macquarie Harbour had returned to the very low levels experienced 12-months earlier,” Dr Ross said.

“This decline led to a fall in faunal numbers in the deeper central area of the harbour.

“However, the more abundant and species rich assemblages in the shallower regions of the harbour appear to have been little changed.

“Soon after the October 2017 benthic survey there was a significant oceanic recharge of oxygen in the bottom waters that continued through much of the summer.”

Dr Ross said the project’s previous progress report in September 2017 had found improved bottom water oxygen conditions, a retraction in the spread of the bacterial mat Beggiatoa around leases and some encouraging signs of faunal recovery.

“But that report also noted the potential for dissolved oxygen levels to return to very low levels in spring, the same time of year that oxygen levels reached very low levels the year before, so these latest results are not unexpected.

“While the results from the middle of last year highlighted the capacity for benthic recovery, sustained faunal recovery in the deeper regions of the harbour will likely depend on the return of more stable and higher oxygen levels in the mid-bottom waters of the harbour,” Dr Ross said.

The project is funded by the Australian Government’s Fisheries Research and Development Corporation (FRDC), the Tasmanian Government, and Tasmanian Salmon aquaculture companies, and will now continue for a further two years until 2020 to allow a better understanding of the oxygen dynamics and interaction of Salmon farming in Macquarie Harbour over a longer period.

The latest report, together with those released in September, May and January 2017, can be found here.