Port of Gladstone (Port Curtis) and Rodds Bay Dugong Protected Area baseline seagrass monitoring surveys (B1.13)

Task leader: Dr Michael Rasheed, Queensland Department of Primary Industries & Fisheries.

Task associate: NA.

Large seagrass meadows were identified in coastal areas within the Port of Gladstone during broad-scale surveys of the east coast of Queensland in 1988 (Figure 1) (Coles et al. 1987). The value of these seagrasses as nursery habitat for juvenile prawns and commercial fish is well recognized (see Watson et al. 1993). Seagrasses in Queensland are also an important food resource for dugong and sea turtles. Recently the value of seagrasses in the Port of Gladstone area to dugong has been recognized by the declaration of the Rodds Bay Dugong Protected Area (DPA). The Rodds Bay DPA encompasses the majority of the port limit area (Figure 1).

Seagrasses can be used as a tool to monitor the environmental health of ports and coastal areas as they show measurable responses to changes in water quality (Dennison et al. 1993). The DPI/CRC-Reef Marine Plant Ecology Group (MPEG) have established seagrass monitoring programs in a number of Queensland ports including Mourilyan, Karumba, Weipa, Thursday Island and Cairns. Seagrass mapping and monitoring in these ports has aided in the planning of dredging programs and port developments as well as assisting in the assessment of effects of port maintenance and development operations on the marine environment. MPEG has also conducted seagrass resource assessments for other Dugong Protected Areas in the region (Upstart Bay, Newry Region, Sand Bay, Llewelyn Bay, Ince Bay and Clareview) (Coles et al. 2002). The results of these surveys had direct implications for the management of dugong within these DPA’s.

Gladstone Port Authority (GPA) is committed to maintaining the health of the marine environment within the port limits, and recognizes that seagrass meadows comprise an important and sensitive component of the marine habitats within the port. GPA have been monitoring seagrasses at 2 locations in the port, Fisherman’s Landing and Wiggins Island, bi-annually since 1997, but there has been no comprehensive survey of seagrasses within the port since 1988 and detailed fine-scale surveys of seagrasses within the port have never been conducted. Seagrass distribution in the deeper offshore areas within the port limits, including the dredge spoil ground is unknown, although deepwater seagrasses are known to occur to the north and south (DPI in prep). Similarly seagrass in areas of the Rodds Bay DPA that lie outside the Gladstone Port Limits have not been investigated since the 1988 broadscale surveys and have not been mapped as part of a fine scale survey.

At the request of Gladstone Port authority we have developed this proposal for fine scale surveys of seagrass resources in the Gladstone port area. The proposed study will provide information required to aid in planning of port development and maintenance programs that will have minimal effects on the marine environment as well as information for more effective management of dugong within the Rodds Bay DPA. The proposed surveys will also provide a baseline from which seagrass monitoring programs can be developed for the Port of Gladstone and Rodds Bay.