Dispersion of seagrass propagules and connectivity among meadows in the Great Barrier Reef World Heritage Area, Queensland, Australia

Recent severe storms and floods in north- eastern Australia damaged or destroyed seagrass meadows along hundreds of kilometres of coastline. The subsequent deaths of turtles and dugong have led to the very status of our iconic... [ view full abstract ]

Recent severe storms and floods in north- eastern Australia damaged or destroyed seagrass meadows along hundreds of kilometres of coastline. The subsequent deaths of turtles and dugong have led to the very status of our iconic Great Barrier Reef World Heritage Area being questioned. How and when will these meadows recover and should on-ground interventions such as re planting be considered? We examined how meadows may re-establish from the dispersion of propagules floating in the water or moved by feeding herbivores. We conducted a study based around Townsville and Abbot Point in North Queensland using a 2 dimensional numeric model developed for studying water movement. We used a decision rule approach releasing propagules in the model between August and November 2011 with actual wind data. Model results suggest connectivity between offshore meadows and inshore meadows is likely to be low, limiting their ability to provide a reservoir of propagules. Time of year, location of release and the location of the propagule (surface or sub-surface) influenced propagule movement. Over 8 weeks propagule movement in excess of 400 kilometres was common. An initial analysis of “fragility” identified hotspots where propagules from many source meadows accumulate and re-establishment would be more likely. We report on the value of this exercise and management implications.