Port of Weipa Long Term Seagrass Monitoring: September 2010

McCormack, C.V., Rasheed, M.A., and Unsworth, R.K.F. (2011) Port of Weipa Long Term Seagrass Monitoring: September 2010. Report. Department of Employment, Economic Development and Innovation (DEEDI), Cairns, QLD, Australia.

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Seagrass habitats provide important ecological functions in the coastal zone including provision of primary productivity in the marine environment and nursery habitat for key fisheries species. The wide distribution on seagrasses in Queensland, and their capacity to show measurable responses to changes in water quality make them ideal candidates for monitoring the health of the marine environments. A network of long term seagrass monitoring sites has been established at various port locations throughout Queensland to assist Fisheries Queensland and port managers in planning and management to ensure port activities are having a minimal impact on the marine environment and fish habitats. The program is also used to help separate natural from anthropogenic change to seagrass meadows.

This report details the results of the September 2010 monitoring program in the Port of Weipa. Seagrasses in the Port of Weipa remained in a reasonable but vulnerable condition. Several meadows that had shown a long term declining trend since monitoring began in 2000 recorded a significant increase for the first time in 2010. The declines were likely associated with natural shifts in tidal exposure and changes in light and temperature associated with local climate conditions. The declines had been particularly concerning for Enhalus acoroides meadows, especially the large intertidal meadow opposite Lorim Point, where biomass reached a record low in 2008. In response to the declines, North Queensland Bulk Ports (NQBP) and Fisheries Queensland conducted an additional survey in both April 2009 and May 2010 to determine whether the large Enhalus meadow was in a healthier state outside of the regular survey period. The additional survey found that biomass was also significantly lower than found in past assessments at a similar time of year.

During the regular September 2010 monitoring survey, mean above-ground biomass in the large Enhalus meadow of most concern had increased significantly from the previous year and was significantly higher than the past five years of monitoring. The intertidal Halodule uninervis meadow on the Western bank of the Hey River had also re-established after disappearing in 2009. Changes in biomass for these meadows over the course of the monitoring program are significantly correlated with the amount of daytime tidal exposure in the month prior to the survey as well as the amount of solar radiation in the twelve months prior to monitoring.

Seagrasses appear to have been resilient to the impacts associated with regular port maintenance dredging during the life of the current monitoring program. However, despite the positive signs of recovery for Enhalus meadows in the port, they are still in a potentially vulnerable state. An examination of light and temperature conditions at vulnerable seagrass meadows established in the port after the September 2010 survey will significantly enhance the ability of the monitoring program to pinpoint the causes of seagrass change. These data are currently being collected and results will be included the 2011 report.

Item ID: 45812
Item Type: Report (Report)
Keywords: recovery, resilience, management, environmental monitoring, marine monitoring, marine water quality, seagrass, reproduction, seagrass habitats, Port of Weipa, port development, dredging
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Funders: North Queensland Bulk Ports Corporation (NQBP), Fisheries Queensland (FQ), Department of Employment, Economic Development and Innovation (DEEDI)
Date Deposited: 21 Sep 2016 23:01
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 50%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 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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