Long-term seagrass monitoring in the Port of Mourilyan: November 2010

Fairweather, C.L., McKenna, S.A., and Rasheed, M.A. (2011) Long-term seagrass monitoring in the Port of Mourilyan: November 2010. Report. Department of Employment, Economic Development and Innovation (DEEDI), Cairns, QLD, Australia.

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This report details results from the October/November 2010 seagrass monitoring for the Port of Mourilyan, conducted as part of the annual long-term monitoring program. The program was developed following a baseline survey in December 1993 and examines selected representative seagrass meadows in Mourilyan Harbour. Total area of each monitoring meadow, species composition and seagrass density (above-ground biomass) were measured for comparison with previous surveys. The program is used to assess the marine environmental health of the port and as a tool to ensure that port operations and maintenance do not have an adverse effect on the marine environment and forms a key location in the assessment of the health of Queensland’s seagrass and fisheries habitats.

In 2010 seagrasses in Mourilyan Harbour had declined to a critical level. Three of the five monitoring meadows were no longer present and the two remaining meadows only consisted of isolated remnant patches. These losses have added to declining trends for seagrasses in Mourilyan that have occurred over recent years, resulting in seagrasses reaching their lowest area and abundance recorded in the monitoring program. Of greatest concern is the complete loss of the previously dense and highly productive Zostera capricorni seagrass meadow that has been a permanent feature of Mourilyan Harbour during the 17 years of monitoring. The causes of the continued seagrass declines were potentially related to another season of high rainfall and catchment water quality issues. However, in the absence of any local water quality monitoring information, it is difficult to define the exact causes of decline. It is highly unlikely that port activities were behind the seagrass changes as there have been no significant changes in port operations in recent years. However, due to the fragile condition of seagrass in Mourilyan Harbour extra caution should be applied to future activities that have the potential to impact on seagrass communities.

The highly vulnerable state of seagrasses in Mourilyan Harbour in 2010 means that measures to reduce further impacts to their health and resilience may be required to assist in their longer term protection and recovery. The relationships observed between seagrass biomass and climate variability are indicative only, and the monitoring program would be enhanced in the long-term with additional investigations and monitoring measures. Further investigation into water quality within the Port of Mourilyan for example would greatly assist in determining whether land-based run-off is influencing the decline of seagrasses within the port. Given the fragile state of seagrasses, continued monitoring as well as further investigations of the drivers of seagrass change, capacity for recovery and indicators of stress are recommended to ensure their longer term recovery and to effectively manage these marine habitats.

Item ID: 39703
Item Type: Report (Report)
Keywords: seagrass habitats, port management, recovery, resilience, dredging, marine monitoring, environmental monitoring
Funders: Far North Queensland Ports Corporation (FNQPC) trading as Ports North, Qld Department of Employment, Economic Development and Innovation (DEEDI)
Projects and Grants: DEEDI Marine Ecology Group (MEG)
Date Deposited: 25 Aug 2015 05:51
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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