Standard Presentation Australian Marine Sciences Association 2026 Conference

Earth observations of mangrove forests of the Gulf of Carpentaria reveal spatio-temporal scale of environmental drivers and lateral space available for adaptation are crucial for interpreting sea-level rise risk to mangrove forests (139722)

Rogerio Gonsalves 1 , Emma Asbridge 1 , Jeffrey Kelleway 1 , Kerrylee Rogers 1 2
  1. School of Science and Environmental Futures Research Centre, University of Wollongong, Wollongong, NSW, Australia
  2. School of Geosciences, University of Sydney, Sydney, NSW, Australia

Earth observation records spanning more than five decades reveal mangrove forests fringing the Gulf of Carpentaria are highly dynamic, yet remarkably resilient. The Gulf comprises broad, geomorphologically complex coastal floodplains experiencing high rates of relative sea-level rise, but remains largely undeveloped, with minimal direct anthropogenic disturbances. This study synthesises mangrove forest changes in response to multiple environmental pressures operating across spatial and temporal scales. Mangrove extent increased over the late 20th century, with episodic dieback causing short-term contractions in 1990, 1994, 2016 and 2019; these declines in extent were followed by periods of recovery. The most pronounced dieback of 2015/16 coincided with climatic and tidal oscillations operating across the region, highlighting the sensitivity of mangroves to compound environmental forcing rather than single drivers. Stochastic events that influence mangrove forest condition, particularly cyclones, exhibited a smaller spatial footprint and while recovery may be slow or limited, the return frequency of stochastic events is low. For example, Cyclone Owen disturbed ~8.3km2 of mangrove at Limmen Bight, representing only 0.4% of the baseline mangrove extent across the Gulf. Geomorphological processes influencing sediment supply further shape mangrove forest extent and zonation, often supporting shoreline progradation and mangrove forest extension at the seaward margin. This study emphasises the resilience of mangrove forests to multiple environmental drivers operating stochastically and/or episodically. While future mangrove forest persistence will depend on sustained sediment accumulation to maintain seaward margins, the extensive coastal floodplains of the Gulf provide substantial capacity for landward retreat should sea-level rise as anticipated. Reframing mangrove dieback and the ecological effects of sea-level rise in the context of spatio-temporal scale of environmental drivers and accounting for the lateral space available for reorganisation of mangrove forests as they adapt to environmental drivers is critical for communicating risk and implementing restoration activities.