Thomas, R., Rasheed, M.A., and McKenna, S.A. (2005) Long term seagrass monitoring in Cairns Harbour and Trinity Inlet: December 2004. Report. Department of Primary Industries and Fisheries (DPI&F), Cairns, QLD, Australia.

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Abstract

This was the fourth annual survey in the Cairns Harbour and Trinity Inlet long term seagrass monitoring program. In this survey, seagrass area and biomass continued the general trend of recovery that was established last year following the significant declines that had occurred in 2002. Changes to seagrass meadows were different between intertidal and subtidal meadows with recovery generally occurring in intertidal areas and declines in subtidal meadows. The largest increase in area occurred in the large Bessie Point meadow in eastern Trinity Inlet with significant recovery in biomass and area also occurring in the intertidal meadows at Ellie Point and the Esplanade.

The observed changes to seagrasses appear to be strongly linked to prevailing climate conditions. The higher temperatures, increased solar irradiance and lack of significant wetseason rainfall thought to have triggered the losses of intertidal seagrasses leading up to 2002 had all returned to more "normal" levels during 2004.

The substantial increases in density and area of dense Zostera capricorni meadows in Cairns were likely to have a flow-on effect to local fisheries. The increase in these important tiger prawn nursery habitats coincided with an increased commercial catch in the far north area. In central Queensland where similar Zostera meadows declined there were no increases in the commercial tiger prawn catch. Increased seagrass abundance was also likely to have positive effects for endangered dugong and turtle in the area with substantial increases in preferred food species occurring in 2004.

The changes observed for seagrasses in Cairns in 2004 were similar to other Queensland locations, such as Mourilyan and Karumba, where seagrass monitoring programs were also conducted. The common changes between locations suggested that regional climate rather than local factors were the major driver of seagrass change in 2004.

Recovery of seagrass habitats in Cairns Harbour and Trinity Inlet indicated the marine environment was relatively healthy in 2004. The monitoring program is strengthening our understanding of the relationships between seagrass abundance, climatic changes, anthropogenic disturbance and fisheries productivity, and assisting in the management of port and urban activities that will have minimal impacts on important marine habitats.

Item ID:	39889
Item Type:	Report (Report)
ISSN:	0727-6273
Keywords:	seagrass habitats, port management, recovery, resilience, dredging, marine monitoring, environmental monitoring
Funders:	Trinity Inelt Waterways, CRC Reef Research Centre
Projects and Grants:	DPI&F Marine Ecology Group (MEG)
Date Deposited:	25 Aug 2015 05:40
FoR Codes:	05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 50% 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 50%
SEO Codes:	96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 50% 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50%
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