Urchins threaten seagrass

NOORAMUNGA Marine and Coastal Park has a prickly problem.

The native purple sea urchin, Heliocidaris erythrogramma, has multiplied into such high numbers in areas of the park, it is now devouring seagrass and creating bare areas of sand called urchin barrens where the seagrass once grew.

Nooramunga Marine and Coastal Park is part of the Corner Inlet Ramsar Site, a wetland of international significance under the Ramsar Convention and is the only place in Victoria where Broad-leaf seagrass, Posidonia australis, forms large seagrass meadows, making it a unique and special place.

The loss of seagrass caused by the over-abundant urchins may have a significant impact on the park’s biodiversity, as the seagrass is a key part of the local marine ecosystem, supporting a range of marine life including species important in the local fishery.

To prevent potential impacts, Parks Victoria undertook an innovative trial in autumn 2017 involving Victorian Fisheries Authority and a dedicated group of volunteers.

The team snorkelled their way through the shallow waters and incredibly hand-culled more than 57,000 urchins in just two days.

This initial trial was deemed successful with evidence of seagrass returning in the areas the urchins were culled. There are now plans in place for another operation to be conducted in September 2018.

In the meantime, due to their commercial viability and to expedite the removal of the pesky sea urchins during the winter, Parks Victoria has formed a partnership with the Victorian Fisheries Authority for the commercial collection for urchins through issuing of special permits to authorised commercial fishermen within a specified timeframe.

Parks Victoria marine pest officer Jonathon Stevenson said, “Urchin barrens are a new issue in Victorian seagrass meadows. We don’t really know what is causing it but action to control them is vital before they completely extinguish the seagrass.”

“Because this is a novel environmental problem, we haven’t got other examples or studies to inform us. We are pioneering a control program using science and adaptive management.

“Our partnership with Victorian Fisheries Authority in providing limited special permits provides an opportunity to achieve both conservation outcomes and a commercial product.”

Victorian Fisheries Authority director- fisheries policy, management, science and licensing Dallas D’Silva said, “The research permits being offered at present provide a great opportunity for the industry to work together to improve fish habitat and productivity in the inlet.”

Keeping watch: Steffan Howe, Parks Victoria marine science manager, studies the spread of urchins in Corner Inlet.

Under attack: prolific spreading of urchins is threatening seagrass meadows in Corner Inlet.

Short URL: http://thestar.com.au/?p=24960

Posted by on May 23 2018. Filed under News. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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