Long-term monitoring of Port of Mourilyan seagrass (B1.15)

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

Task associate: NA.

An initial four-year seagrass monitoring program was undertaken in the Port of Mourilyan from 1994-1997 (McKenzie et al. 1996;1998). This monitoring program found large areas of seagrass in Mourilyan Harbour, and established a range for seasonal and inter-annual variation in seagrass abundance and distribution. At the completion of the initial monitoring program, DPI recommended continued surveying of seagrasses in Mourilyan Harbour every three years or after a natural event (e.g. cyclone, flooding) that had the potential to impact seagrasses in the harbour. As part of a long term monitoring strategy, PCQ commissioned seagrass monitoring surveys for the Port of Mourilyan in July 2000 and December 2000. Those surveys indicated seagrass distribution and abundance had greatly reduced since that last survey in 1997, most likely due to flooding from higher than average rainfall in the Moresby River catchment during the 1999 and 2000 wet seasons (Thomas and Rasheed 2001). No surveys were conducted during 1998 or 1999 so it was not possible to determine whether seagrass declines occurred during this time. A re-survey of seagrass meadows in December 2001, following 12 months of 'average' rainfall patterns, indicated substantial recovery of the seagrass meadows had occurred since December 2000 (Thomas and Rasheed 2002). In the report for the December 2001 survey, DPI recommended that future seagrass monitoring surveys for the Port of Mourilyan be conducted on an annual basis (Thomas and Rasheed 2002). Annual surveys would enable better interpretation of changes occurring in the seagrass meadows, particularly when discerning impacts of port activities from other environmental (climatic) impacts.