News

Assessing reef health in the southern D’Entrecasteaux Channel

An increase in human activity in the southern D’Entrecasteaux Channel has triggered an investigation about how the related sustained low-level organic enrichment will affect the health and function of the region’s rocky reef ecosystems.

Temperate reef ecosystems in south-eastern Tasmania have intrinsic natural biodiversity and conservation value. They are also important for tourism and recreation, and fisheries harvests such as abalone, rock lobster and scalefish.

To better understand the functional health of reefs in the lower Channel, IMAS researchers have established a baseline in this region against which future monitoring data can be measured.

Lead author of the recently-released reef assessment report, Dr Camille White, said the ability to identify when temperate reefs are under stress is a significant challenge for managing these ecosystems.

“Our IMAS team has been developing and trialling methods to detect when reef ecosystems are changing due to organic enrichment, with a focus on regions where salmon farming is expanding,” Dr White said.

“We are trialing a Rapid Visual Assessment (RVA) method and Abalone Recruitment Modules (ARMs), which both give important, but very different insights into aspects of reef function.

“The RVA method suits a more integrated assessment of reef health, while monitoring the recruitment of a commercially important species using ARMs addresses an industry focus.

"Choosing the method to use in any ongoing reef monitoring program will depend on the management question of interest.”

From the project, researchers have established new reference sites of importance to the abalone industry, including Mouldies, Black Reef, Middle Ground and George III, as well as building a baseline to detect any future change in the southern Channel region.

“Ongoing monitoring of these sites could provide greater resolution of natural variability and help to develop indicator thresholds for a loss of ecosystem function,” Dr White said.


The Rapid Reefs project was funded by the IMAS Sustainable Marine Research Collaboration Agreement (SMRCA) program. Visit our Salmon Interaction Team website, or read the report here.

Images:

  • Top right: IMAS diver uses the Rapid Visual Assessment (RVA) method to document reef parameters.
  • Centre left: Callipers are used to measure abalone length to the nearest millimetre and the data is then used for abalone recruitment modules.
  • Bottom: To better understand the functional health of reefs in the lower Channel, IMAS researchers have collected the data to establish a baseline in this region against which future monitoring data can be measured.

Published 26 May 2021

Authorised by the Executive Director, Institute for Marine and Antarctic Studies
May 26, 2021