Assessing the sensitivity of coral connectivity modelling to mesh resolution in the Great Barrier Reef (or "How fine is fine enough?")

Saint-Amand, Antoine;Hanert, Emmanuel;Lambrechts, Jonathan
(2019) 92nd Australian Coral Reef Society Conference — Location: Moreton Island, Queensland, Australia (7.May.2019)

Files

No attached file found for this publication.

Details

Authors
Abstract
Over the past decade, constant efforts have been put in modelling the connectivity between the 3000+ individual reefs composing the Great Barrier Reef (GBR). However, the computing cost of such models compared to the vastness of the GBR often results in using coarse-resolution models or to work on limited areas. In this study, we use the 2D unstructured-mesh coastal ocean model SLIM (slim-ocean.be) to assess the impact of mesh resolution on model results. SLIM uses unstructured meshes that offer the flexibility to vary the spatial resolution so that computational resources can be allocated where they are most useful: the level of detail is set at a high precision near reefs, islands and along the coast. On the other hand, resolution is coarser in deeper areas, where SLIM is coupled with eReefs model (3D, 4 km fixed resolution). In this work, we assess the effect of mesh resolution on connectivity estimates. For this purpose, we built five different meshes for which the maximum resolution ranges from 250 m to 4 km. For each setup, we model ocean currents to simulate larval dispersal over the whole GBR. We then compare the effect of mesh resolution on different connectivity indicators (local retention and self-recruitment, average connectivity length, community structure...). Our results suggest that with a too coarse resolution (typically >500 m), most of the local processes happening in the wake of reefs are missed by the model. Indeed, those local processes are more likely to retain larvae close to the source reef. A too coarse resolution will thus lead to over- estimate long-distance connectivity and hence under-estimate local retention and self- recruitment.
Affiliations

Citations

  • APA
  • Chicago
  • FWB

Saint-Amand, A., Hanert, E., & Lambrechts, J. (2019). Assessing the sensitivity of coral connectivity modelling to mesh resolution in the Great Barrier Reef (or “How fine is fine enough?”). 92nd Australian Coral Reef Society Conference, Moreton Island, Queensland, Australia. https://hdl.handle.net/2078.5/117530