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Keep Watch Seagrass

08 March, 2017

Scientists undertaking seagrass research have been busy diving and sampling in Geographe Bay as they continue to monitor the Bay’s seagrass meadows over time to determine if impacts such as poor water quality from the catchment are affecting seagrass health.

The “Keep Watch” seagrass monitoring project, coordinated by Busselton based Community NRM group GeoCatch and funded by Water Corporation has been keeping a keen eye on Geographe Bay’s seagrass meadows since 2012.

GeoCatch has recently secured additional funding from Watercorp to continue the monitoring program for another five years (to 2021).

“We are really pleased to have Watercorp’s ongoing support to continue this important program, GeoCatch Chair Will Hosken said. “The Geographe Catchment is under pressure from increased population growth and intensifying agricultural and horticultural landuse, so nutrient enrichment is a real threat to local waterways and marine ecosystems”, added Mr Hosken.

Nutrients enter the bay from rivers and drains and come from a variety of sources including garden and agricultural fertilisers. Excess nutrients can enhance growth of epiphytes and algae which grow on the seagrass leaves, reducing growth and shoot density. If the seagrass meadows do not remain healthy, the marine fauna that live there will be threatened.

Under the Keep Watch program, research scientists from Edith Cowan University, in partnership with the Department of Parks and Wildlife, monitor the Bay annually. As more annual data is collected to assess change over time at each site, a number of assessment triggers are utilised to indicate if there are any concerns.

Seagrass shoot density is measured as the indicator of seagrass health and a number of other variables are collected to help interpret this indicator, including observations of algal epiphyte cover and seagrass leaf nutrient content.

“Over the past five years, more sites are increasing in shoot density, particularly those sites in the centre of the bay. Changes in shoot density are common from year to year and unless there are large declines or continual declines over time, it is not of concern” said Dr Kathryn McMahon from Edith Cowan University.

Results from the past five years of the program are promising, showing the Bay’s seagrass meadows, which are predominantly the seagrass species Poisidonia sinuosa, to be in overall good condition.

The 2016 Keep Watch report is available on the GeoCatch website https://geocatch.asn.au/resource-category/marine-and-coast/. Stay tuned for the 2017 report -currently a work in progress.