Effects of climate and human activities on mangrove wetland evolution.

Mangrove wetlands are one of the most significant and vulnerable ecosystems in the world, providing a wide range of services including habitat, flood control and carbon storage, among others. Their vulnerability under climate change scenarios has been well documented, but recent works have shown that coastal wetlands have the capacity to accrete following the trend of SLR under particular circumstances. Suspended sediment concentration (SSC) plays a critical role in the accretion mechanisms that support wetland survival.

Wetlands in the Pacific Islands are among the most vulnerable areas to climate change and they receive considerable sediment from croplands (sugarcane) of their inland catchments. This contribution focuses on mangrove wetlands at the mouth of rivers draining into the Great Sea Reef. The objectives of our research are to evaluate the sediment loads from the catchment upstream of the coastal wetlands and to model the ecogeomorphological feedbacks among catchment, wetland and coastal reef lagoon under current conditions and future climate change scenarios. The methodology simulates the hydro-sedimentological behaviour of the watershed, under current and future scenarios with changes in land use (cropland expansion/management) and extreme events (cyclones). The output of this simulation constutute the input for the eco-geomorphological coastal wetland modelling.

This integrated modelling approach provides a better understanding of the main processes and feedbacks among vegetation, sediments and hydrodynamics within the coastal wetland, considering its interactions with the adjacent terrestrial (catchment) and aquatic (reef lagoon) ecosystems.