Port of Abbot Point seagrass, algae and benthic macro-invertebrate community survey: March 2005
Other Publication ResearchOnline@JCUAbstract
This report details the results of a survey of seagrass, algae and benthic macro-invertebrate communities in the northern section of the Abbot Point port limits conducted in March 2005. The survey was commissioned by the Ports Corporation of Queensland (PCQ) as a joint project with the Department of Primary Industries and Fisheries (DPI&F) and the CRC Reef Research Centre to aid in planning for future port expansion with minimal impacts on sensitive fisheries and benthic habitats. PCQ is currently investigating the possibility of expanding the coal loading facilities at Abbot Point to increase port efficiency. A range of survey techniques were used to describe the benthic communities that occurred in the port and included a real time camera system and sled with mini-trawl net towed behind a research vessel and visual assessments by divers in shallow coastal areas. The techniques employed integrated a large area of seafloor at each site and were ideal for describing patchily distributed benthic habitats that typically occur in offshore areas of Queensland's ports. Seagrass communities were the dominant benthic habitat feature with no significant areas of habitat forming benthic macro-invertebrates and only a very low percent cover of algae in the survey area. While seagrass was the dominant habitat, its distribution was confined to the inshore half of the port limits with most seagrass found inshore of the Abbot Point wharf. The northern (offshore) half of the port limits that included the potential wharf expansion areas and the existing spoil ground was characterised by open substrate with no significant benthic communities present. The large areas of seagrass mapped in Abbot Point were likely to play a role in fisheries productivity and contribute significantly to the overall ecological productivity of the area. Many of the seagrass meadows were of a type preferred as food for dugong and may provide an important food source for dugong moving along the coast between nearby Dugong Protection Areas (DPA's) to the north and south of the port. Benthic habitats in the port were typical of those found in other regions that have been surveyed between the mainland and the Great Barrier Reef. There were no areas of unique or unusual benthic life discovered within the survey area. The survey was undertaken at a time that would likely capture seagrass at its seasonal high point and the results in this report provide a good representation of the probable maximal seagrass distribution in the port area. Planned expansion for the Abbot Point wharf would be likely to have minimal impacts on seagrass, algae and benthic macro-invertebrate communities as no seagrass or significant benthic communities occurred within the footprint of proposed extensions. Turbidity plumes associated with dredging operations at the berth pocket have the potential to impact on nearby coastal seagrasses, however there are a number of factors which would help minimise any impact. Offshore currents in the port generally flow parallel to the coast and turbidity plumes would not be expected to migrate significantly into inshore seagrass areas. In addition, dredging for the new wharf is currently predicted by PCQ to take only 2-3 weeks, which is a short duration unlikely to have any significant long-term impact even if the turbidity plume did reach seagrass areas. This was the first time that seagrass and benthic communities have been examined at this scale in Abbot Point so direct historical or seasonal comparisons were not possible. The survey provides a good indication of the location of significant communities in the port but it is likely that many of the communities described would be variable seasonally and between years. This survey provides a baseline from which future comparisons could be made. The port contained several seagrass meadows that would be suitable for ongoing monitoring to assist in assessing any impacts of port activities and to provide an overall picture of marine environment "health" for the port.
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QI05044
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0727-6273
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31
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Department of Primary Industries and Fisheries (DPI&F)
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Cairns, QLD, Australia
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