Bryant, C., Davies, J., Sankey, T., Jarvis, J., and Rasheed, M. (2014) Long Term Seagrass Monitoring in Port Curtis: quarterly seagrass assessments & permanent transect monitoring progress report 2009 to 2013. Report. TropWATER, James Cook University, Cairns, QLD, Australia.

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Abstract

Key findings:

Long-term monitoring at permanent transects revealed that seagrasses in the Western Basin and Rodds Bay underwent distinct seasonal changes as well as significant inter-annual changes in seagrass distribution, abundance and species composition.

Over the duration of the monitoring program (since November 2009), Gladstone has received higher than average rainfall during the majority of wet seasons, punctuated by two of the most extreme flood events on record.

Significant declines in seagrass abundance occurred at all sites during the monitoring program, particularly following the 2010/2011 floods. Some sites showed substantial recovery, particularly in the outer harbour; however inner harbour sites have yet to recover to pre-flood levels.

In January 2013, the Calliope River discharged at record levels and declines in seagrass were detected across most of the monitoring sites. Recovery over the 2013 growing season varied with some sites (e.g. Pelican Banks South) remaining atypically low in seagrass cover.

During 2013 seagrass C:P, N:P and C:N ratios declined at outer harbour sites, indicating that seagrasses were existing in a nitrogen limited, low light and nutrient rich environment following the January flood event.

Seed banks for Halophila ovalis and Zostera muelleri were detected at some locations in the harbour from which recovery could be initiated when conditions are favourable for germination, seedling survival and for subsequent clonal growth and colonisation.

Gladstone seagrasses were capable of rapid clonal growth and the production of flowers, fruits and seeds. However this varied substantially between meadows and time of year. It is likely that propagule limitation at some sites may be inhibiting seagrass recovery.

It is estimated that the major area of dense seagrass in Gladstone, the intertidal Zostera muelleri meadow at Pelican Banks, incorporates up to 0.69 grams of carbon m¯² day-1 into its above-ground biomass, which translates to more than 4 tonnes of carbon per day for the meadow at peak distribution and density.

The most recent survey (November 2014) has revealed significant recovery at the out of Port reference sites at Rodds Bay. In the absence of another extreme wet season in 2014/2015, we expect to see further increases in Rodds Bay and the Western Basin region.

Item ID:	39665
Item Type:	Report (Report)
Keywords:	seagrass, monitoring, assessment
Additional Information:	This report is confidential and cannot be made public.
Funders:	Gladstone Ports Corporation Limited
Date Deposited:	28 Aug 2015 06:00
FoR Codes:	05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 50% 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 50%
SEO Codes:	96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50% 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 50%
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