Long term seagrass monitoring in Port Curtis and Rodds Bay, Gladstone: October 2007

This report details findings of the 2007 annual seagrass monitoring survey for Port Curtis and Rodds Bay. The program was developed from a baseline survey conducted in 2002 and from recommendations of the Port Curtis Integrated Monitoring Program (PCIMP) review.\ud \ud In 2007 seagrasses in Port Curtis were in the healthiest condition recorded since the inception of the monitoring program. Most of the monitoring meadows were at or near their highest recorded density and area. This was particularly true for intertidal seagrass meadows which in several cases had more than doubled in biomass from 2006. However the three subtidal monitoring meadows did not exhibit the same trends. While they remained relatively healthy they had either declined in biomass or area from the previous year.\ud \ud The changes to seagrasses observed in the monitoring program appear to be largely linked to a combination of climate factors and tidal exposure and the natural resilience and capacity for recovery in individual seagrass meadows. Changes observed were consistent between seagrasses within the port infrastructure area and at reference sites in nearby Rodds Bay as well as other Queensland locations where seagrasses are monitored.\ud \ud The presence of seagrass meadows and dugong activity in intertidal areas adjacent to port facilities and infrastructure has implications for port management. Some of the most utilized seagrass meadows also appear to be those in closest proximity to major port infrastructure and proposed areas of expansion. Future port infrastructure developments would require careful management to ensure minimal impacts on these communities. The fact that "healthy" seagrass meadows and dugong activity have continued to exist within the port indicates that these important habitats can co-exist with well managed port activities and development.\ud \ud Increases in density of the highly productive Zostera capricorni meadows over the past two years had positive implications for local fisheries production as these meadows are especially valuable as nursery habitat for juvenile tiger prawns and other commercial and recreational fish species.\ud \ud Post the October 2007 seagrass survey the Gladstone area experienced substantial rainfall and related turbid plumes within the port area which were likely to have a negative effect on seagrasses. The very healthy condition of seagrasses recorded prior to these events may have provided the meadows with a high resilience and potentially greater capacity to recover from flood related impacts.\ud \ud This was the fourth survey in the established annual monitoring program and we have already identified some of the likely climate related drivers of seagrass change. A recent expansion of the seagrass monitoring program within PCIMP has led to a series of turbidity, light and temperature loggers and monitoring stations being established in the seagrass meadows late in 2007 by the Centre for Environmental Management at CQU. With the aid of this new data we will be in a far stronger position to determine the major drivers of seagrass change and will be better able to assess any anthropogenic (human induced) impacts to seagrass meadows that may arise in the future