Determine coral larval dispersal in the Arabian Gulf by modelling reef connectivity

Details

Supervisors

Hanert, Emmanuel ; Scherpereel, Colin

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences et technologies de l'environnement, à finalité spécialisée

Abstract

enThe Arabian Gulf hosts coral reefs that persist under some of the most extreme thermal and salinity conditions endured by scleractinian corals worldwide, yet recurrent mass bleaching events have driven a sustained decline in live coral cover and a structural flattening of the reef framework. In such a semi-enclosed, disturbance-prone basin, the persistence of the remaining reef populations depends on larval connectivity, the demographic backbone of coral metapopulations. The only previous basin-scale assessment covered only the eastern half of the basin and was further restricted to a single spawning event and a generic larval parametrization. Here we show how a three-dimensional high-resolution hydrodynamic model coupled with a Lagrangian Particle Tracker can resolve coral larval connectivity across the entire Gulf, over four consecutive spawning seasons (2022–2025) and for three species with contrasted life-history strategies (Acropora downingi, Platygyra daedalea, Porites harrisoni). Connectivity is characterised through reefscale indicators and a Leiden-based community-detection analysis. Out-degree, in-degree and restoration-index hot-spots are consistently confined to tidally-forced nearshore environments across the eastern Qatar–UAE shelf, the Saudi Arabian coast and the Bahrain area, while the highest weighted connectivity lengths align with the Hormuz islands and the central Iranian coast. The Saudi coast emerges as both a continuous stepping-stone corridor and the principal topological connector of the basin-wide larval network. At the basin scale, inter-community fluxes outline a counter-clockwise larval transport interrupted by a connectivity gap between Bahrain and northern Qatar, identifying this sector as a conservation priority of basin-scale consequence. The ethodological framework developed here is transposable to comparable semi-enclosed basins, and the connectivitymatrices constitute a reusable dataset for sector-specific studies within the Gulf. To our knowledge, this work provides the first whole-basin, multi-year and multi-species assessment of coral connectivity in the Arabian Gulf.