Standard Presentation (15 mins) Australian Marine Sciences Association 2022

Field-Validating Coral Larval Connectivity Models To Inform Spatial Planning For Reef Restoration (#317)

Robert A. B. Mason 1 , Clothilde Langlais 2 , Julian Uribe-Palomino 1 , Bec Gorton 2 , Mark Tonks 1 , Frank Coman 1 , John Andrewartha 2 , Kinam Salee 1 , Pascal Craw 2 , Peter Mumby 3 , Anthony J. Richardson 1 3 , Russ Babcock 1 , Christopher Doropoulos 1
  1. CSIRO Oceans and Atmosphere, St Lucia, Queensland, Australia
  2. CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia
  3. University of Queensland, St. Lucia, Queensland, Australia

Marine spatial planning of tropical coastal systems often relies on understanding coral larval connectivity among reefs, which is increasingly being incorporated into reef restoration planning. Sophisticated hydrodynamic models that can simulate larval dispersal through Lagrangian particle tracking have become the standard technique to estimate connectivity within reef systems. Whilst the physical basis of such modelling is mature, few connectivity models have been field-validated, and the proportion of coral larvae transitioning to settlement on a reef is mostly unknown. To support restoration planning on the Great Barrier Reef, we modelled coral dispersal and ground-truthed predictions using high intensity spatial and temporal sampling of larvae and newly settled recruits following the 2021 mass spawning in the Capricorn-Bunker Group. Early results suggest that particle tracking simulations successfully predicted the relative rate of larval arrival at several field sites, but not all. Moreover, while daily settlement rates closely matched the relative planktonic abundance of coral larvae, accumulated settlement over a two-week period diverged from larval arrival rates – a possible signature of selectivity in settlement or early post-settlement mortality. To explain these outcomes and improve connectivity modelling, the influence of larval competency rates, localised environmental conditions, and benthic composition are being further investigated.