Long-term effects of flooding events on the resilience and recovery of tropical seagrass habitats

In the summer of 2010/2011 Queensland experienced some of the worst floods on record. Plumes associated with flooding have the potential to negatively impact seagrass habitats through high nutrient loads, burial, sediment destabilisation, reducing light availability and lowering salinity. Over the last 17 years a network of long-term monitoring sites have been established around Queensland to examine the condition and trend of the state's valuable seagrass habitats. Results have shown major declines in seagrass across the east coast of Queensland since the 2010/2011 floods. Many of these seagrass communities were already in decline prior to the 2010/2011 floods meaning that these communities were likely to be less resilient to further impacts and may have had a reduced capacity for recovery. Our long-term monitoring data has previously demonstrated seagrass loss related to flood events, however tropical seagrass meadows have shown a capacity for recovery returning to pre-flood levels within 4 months to 5 years. Recovery was dependent on the presence of locally available propagules and established seed banks from which recovery could occur. While seagrasses along the urban east coast were in poor condition, in other regions of the state including northern Cape York, the Torres Strait and the Gulf of Carpentaria seagrass remained in relatively good condition. The vulnerable state of seagrass habitats on the east coast of Queensland, and differences between regions underscores the need for continued monitoring across regions to ensure the long-term viability of these ecologically important marine habitats and appropriate management of the resource. Long-term monitoring programs can play an important role in providing quality data on seagrass status which can assist managers to make decisions on how to respond with greater confidence