Assessing the response of Seychelles fish biodiversity to protection status and seascape conditions

Details

Supervisors

Hanert, Emmanuel ; Dobbelaere, Thomas

Faculty

Faculté des bioingénieurs

Degree label

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

Abstract

Marine protected areas (MPAs) are a common tool used worldwide to enhance the protection of marine biodiversity. In recent years, MPAs and MPA networks have begun to include the question of connectivity, which manifests through the movement of juveniles and adults, in their creation with the goal to enhance population stability and diversity in and out of MPAs. In this study, we investigate the connectivity of the current MPA network located on the Mahé Plateau, Seychelles with the goal to identify the dispersal dynamic of fish larvae and potential gaps in the network. To do so, we use a three-dimensional ocean model, SLIM3D, over a seven-month period. We couple it with a larval dispersal model based on the behaviour of Lutjanus sebae, a key commercial and overexploited fish in the Seychelles. Larvae behaviour is divided into five main life stages: egg, pre-flexion, flexion, post-flexion and settlement. We then conduct a connectivity analysis on the MPAs and reefs located on the Mahé plateau. Our results suggest that the varying dynamic of the currents has an impact on the direction of exchanges of larvae between the inner islands and outer reefs of the plateau as well as on the percentage of settling larvae which reaches a peak in January (12.5%). We find that the probability of exchange between MPAs currently reach up to 2.8% and identify potential locations of new MPAs on reefs with a high potential of exporting and receiving larvae around Mahé island.