Port of Abbot Point long-term seagrass monitoring: annual report 2013-2014

Key Findings:\ud \ud This report presents the latest findings of the long-term seagrass monitoring program for the Port of Abbot Point that has been conducting quarterly assessments of seagrass since 2008.\ud \ud 1. After 19 months of declines following Tropical Cyclone Oswald and associated rainfall, high winds and flooding, offshore seagrasses (Halophila species) showed significant increases in biomass in September and December 2014;\ud \ud 2. Inshore monitoring meadows have yet to show substantial recovery, however the presence of Halodule uninervis and Zostera muelleri at some of the inshore meadows are positive signs of initial re-establishment and recovery;\ud \ud 3. The first ever recorded occurrence of Halophila tricostata in the Abbot Point/Bowen area was made in the September 2013 survey. Halophila tricostata was again present in the September 2014 survey.\ud \ud 4. Light and climate conditions were favourable for seagrass growth and the delay in recovery observed is likely a reflection of previous large scale declines limiting the availability of propagules from which recovery could be initiated and sustained;\ud \ud 5. Initial light requirement thresholds were developed for Halophila species and Halodule uninervis derived by a review of the literature, ongoing studies and analysis of in situ data on light and seagrass change collected at Abbot Point between 2013 and 2014;\ud \ud 6. Future plans for incorporating light based triggers for seagrass management at Abbot Point should remain flexible to allow additional information from ongoing data collection on site, or any additional new studies to be incorporated in refining the initial threshold;\ud \ud 7. Assessments of seagrass seed banks and their viability will be a key addition to the monitoring program to understand their resilience to impacts and potential for recovery;\ud \ud 8. The declines in Abbot Point seagrasses over recent years mean that they likely have a reduced resilience to further impacts and stressors. The cumulative impacts of natural stressors need to be considered in conjunction with future developments associated with port expansions in formulating management strategies to protect seagrasses and allow for their continued recovery