Port of Townsville Seagrass Monitoring Program: 2019

This report presents the results of the first year of the Channel Upgrade Seagrass Monitoring Program and builds on the Long-term Seagrass Monitoring Program established in 2007. The Townsville region was affected by heavy rainfall and flooding in February 2019 and concerns were raised about the impact these events had on seagrasses. The May 2019 whole-of-port senescent season survey indicated that these floods and the associated sediment plume did not have as great an impact on seagrass as was expected, with seagrass found throughout much of the Townsville port limits. The October 2019 whole-of-port peak season survey indicated that there may have been a ‘lag effect’ or legacy of the February floods, with seagrass density(biomass) at coastal meadows not returning to ‘typical’ peak season levels. The area of coastal seagrass meadows was similar to that previously recorded in peak season surveys, despite the overall density of coastal seagrass being lower than previous years. A significant deep-water seagrass meadow was recorded in the peak season survey with seagrass observed at 14.4m (below mean sea level). Such an extent of deep-water seagrass has not been recorded in Townsville since 2008. The overall condition of seagrass in the meadows monitored as part of the previously established Long-term Seagrass Monitoring Program was satisfactory in 2019. Dugongs and their feeding trails in seagrass meadows were observed during both 2019 field surveys. Continued persistence and growth of seagrass in Townsville will be contingent on environmental conditions being favourable, particularly during the 2019/20 wet season.