Speed Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Bio-Physical Determinants of Sediment Accumulation on Coral Reefs (#88)

Sterling B Tebbett 1 , Jodie A Schlaefer 2 , Casey L Bowden 1 , William P Collins 1 , Christopher R Hemingson 3 , Scott D Ling 4 , Juliano Morais 1 , Renato A Morais 5 , Alexandre C Siqueira 1 , Robert P Streit 1 , Sam Swan 1 , David R Bellwood 1
  1. James Cook University, Townsville City, QLD, Australia
  2. Commonwealth Scientific and Industrial Research Organisation (CSIRO), Townsville, QLD, Australia
  3. Department of Marine Science, The University of Texas at Austin, Port Aransas, Texas, United States of America
  4. University of Tasmania, Hobart, Tas, Australia
  5. University of Perpignan, Perpignan, France

Sediments are found on all coral reefs around the globe. However, reef sediment dynamics, and associated bio-physical drivers, are rarely examined simultaneously over matching spatial and temporal scales. This has resulted in a partial and uncertain understanding of how sediments and living reef systems are connected. In this talk, I will explore the implications of a multidisciplinary study in which we simultaneously quantified seven sedimentary processes and associated bio-physical drivers across seven different reef habitats/depths. In the study, we found that a substantial load of suspended sediment passed over the reef; a load theoretically capable of replacing the entire standing stock of on-reef turf sediments in just eight hours. However, quantification of actual sediment deposition suggested that just 2% of this passing sediment settled on the reef. The data also revealed a marked disconnect between patterns of sediment deposition and accumulation on the benthos, with the ‘post-settlement’ fate of sediments dependent on local hydrodynamic conditions and reef geomorphology. From an ecological perspective, the data suggests key contextual constraints (wave energy and reef geomorphology) may predispose some reefs or reef areas to high-load turf sediment regimes, which carry important implications for how these locations function in a changing world.