Western Indian Ocean Marine Science Association

A molecular consideration of Western Indian Ocean marine fish connectivity and differentiation at multiple spatial and temporal scales and its implications for conservation and resource management

Lead Institution: South African Institute for Aquatic Biodiversity (SAIAB)
Project Country:
Investigators: Gavin Gouws
Project Summary:

Effective conservation and management measures are necessary for the conservation and sustainable use of marine resources in the Western Indian Ocean (WIO) region. One such measure is the designation of Marine Protected Areas. The current MPA network in the WIO
is ineffective for conserving diversity and protecting resources.
· Such interventions need to be underpinned with the understanding of the historical and contemporary processes that influence the fauna, at the relevant spatial scale, and need to consider a region-wide approach to provide recommendations at this scale.
· There is insufficient understanding of the contemporary, ecological connectivity among MPAs across the region, whether these represent demographically open or closed systems (sources and sinks) and the extent to which these provide an export of larvae or adults to areas outside. This hampers the integration of MPAs into an effective reserve network.
Further, the lack of clarity on the biogeographic and historical origins of the WIO fauna, and little knowledge of phylogeographic and biogeographic breaks precludes an understanding of the features that influence connectivity

What were the problems the project intended to address?:

There is insufficient understanding of the contemporary, ecological connectivity among MPAs across the region, whether these represent demographically open or closed systems (sources and sinks) and the extent to which these provide an export of larvae or adults to areas outside. This hampers the integration of MPAs into an effective reserve network.
Further, the lack of clarity on the biogeographic and historical origins of the WIO fauna, and little knowledge of phylogeographic and biogeographic breaks precludes an understanding of the features that influence connectivity.
With the difficulties in studying connectivity directly, a genetic approach provides a valuable and widely accepted, indirect means of examining connectivity across the region.

Project Objectives:

This study aimed to examine connectivity and regional intraspecific differentiation in several reef fish species across the WIO at various spatial scales, considering processes over ecological and evolutionary timeframes. Specifically, patterns of fine-scale genetic structure and scales of connectivity were investigated in three species of importance to regional fisheries, in order to identify open and closed systems and localities that are critically isolated. Broad-scale patterns of differentiation and relationships among the regions of the
WIO were investigated in nine reef species, with a view to revealing unique biogeographic regions in the WIO

Study Sites:
Publications:

1. Muths D, Tessier E, Gouws G, Craig M, Mwale M, Mwaluma J, Mwandya A and Bourjea J. In press. Restricted dispersal of the reef fish Myripristis berndti at the scale of the South-West Indian Ocean. Marine Ecology Progress Series.
2. Muths D, Tessier E, Gouws G, Mwale M, Mwaluma J, Mwandya A and Bourjea J. Accepted (pending major corrections). Genetic connectivity of the reef fish Lutjanus kasmira at the scale of the West Indian Ocean. Canadian Journal of Fisheries and Aquatic Sciences.
Papers Under preparation:
3. Muths D, Tessier E, Gouws G, Mwale M, Mwaluma J, Mwandya A and Bourjea J. In prep. Hierarchic genetic differentiation in the grouper Epinephelus merra from the Indo-Pacific
scale to the within West- Indian Ocean scale.
4. Gouws G, Mwale M, Bourjea J, Muths D, Mwaluma J, Mwandya A and Gon O. In prep. Persistence of geographically restricted lineages of Abudefduf vaigiensis against a backdrop of little differentiation.
5. Gouws G, Mwale M, Bourjea J, Muths D, Mwaluma J, Mwandya A and Gon O (and possibly others). In prep. Lack of genetic structure across the Indo-Pacific barrier in the ember parrotfish
(Scarus rubroviolaceus).
6. Gouws G, Mwale M, Bourjea J, Muths D, Mwaluma J, Mwandya A and Gon O (and possibly others). In prep. The lack of genetic structure across the WIO in the domino (Dascyllus trimaculatus).