It’s all in the genes: using coral genetics to assess population structure and connectivity between KZN’s MPAs

By: Jessica Gilmore and Dr Dave Pearton

Corals reefs constitute a very small percentage of ocean habitat but play a disproportionately large role by providing important refuge, nursery and feeding grounds for up to 25% of marine species. They are also under huge pressure from numerous threats including climate change, pollution and overfishing. Marine Protected Areas (MPAs) are critical tools in helping to protect these vulnerable ecosystems. One of the most important criteria for the success of MPAs are whether they provide sufficient protection for a variety of ecosystem while maintaining population connectivity. One way to ensure this is to design MPA networks of interconnected areas that are more resilient than the single MPAs would be on their own. The Connectivity And disPersal beTween prOtected aReas (CAPTOR) project funded by the National Research Foundation (NRF-DST) and ACEP (African Coelacanth Ecosystem Programme) seeks to determine whether the network of new and existing MPAs along KZN and Eastern Cape coast fulfils this criterion. For this component of the larger CAPTOR programme we are looking at whether the current MPA network in KZN does this effectively for critical habitat forming benthic species. In this case we are studying a hard coral (Stylophora pistillata) and a soft coral (Sinularia brassica) which were known to be present in all of our sample locations. Samples have been collected using SCUBA and Remotely Operated Vehicles (ROVs) at three MPAs (iSimangaliso Wetland Park, Aliwal Shoal and Pondoland) as well as representative reefs located in the “gaps” between MPAs. We have used modern genetic methods, including some cutting edge genetic sequencing techniques, to look at how populations of corals in these different areas are related to each other and whether coral larvae can move between areas. This study has revealed a fascinatingly complex picture where populations that are physically close to each other are not necessarily the most related and where coral larvae can move over 300 km from the warm subtropical iSimangalio Wetland Park to the much cooler Aliwal Shoal MPA.