Port of Karumba long-term seagrass monitoring: October 2010

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, such as seagrass habitats. 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 of 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. This report details the results of the October 2010 monitoring program in the Port of Karumba. Seagrass meadows in the Port of Karumba were found in 2010 to be in a healthy and productive state with dugong feeding trails seen in 57% of the sites that had seagrass. Although meadow area declined in 2010, the meadow remains spatially expansive and dense, with biomass and area values above the 17 year averages. The variability in biomass and distribution seen in the Karumba monitoring meadow throughout 17 years of monitoring have been linked to river flow, air temperature and long-term tidal exposure cycles (Rasheed and Unsworth 2011). Above-ground biomass had a positive correlation with river flow, while air temperature was a negative correlate with biomass. Meadow area was observed to have a positive correlation with the number of hours of daylight tidal exposure (Rasheed and Unsworth 2011). Results of the 2010 survey indicate that the marine environment of the port was in a healthy condition and that anthropogenic activities including dredging and other port and urban activities are unlikely to have had a significant impact on seagrasses in Karumba over the previous 12 months. Although currently in a healthy and robust state, natural conditions have the capacity to reduce seagrass resilience, to the point where they may become vulnerable to impacts such as dredging. This monitoring program provides the tools to assess the vulnerability of seagrass and take appropriate actions if required