South Africa’s coral reefs stretch for approximately 150 km along the northern KZN coast from north of Cape Vidal to the Mozambique border. The reefs are separated into 3 groups termed the northern, central and southern complex and are situated in the Maputaland Marine Reserve and St Lucia Marine Reserve. Combined these two marine parks form part of the iSimangoliso Wetland Park, which was proclaimed a World Heritage Site in 1999. Although all of the coral reefs lie within marine protected areas (MPA) they do not have the same levels of protection i.e certain reefs are located within sanctuaries while others are designated multiple-use zones.
Why are MPAs necessary?
Unless managed sustainably, the uses and users of marine ecosystems can threaten, change and destroy the very processes and resources that they depend on.
Marine protected areas help protect important habitats and representative samples of marine life and can assist in restoring the productivity of the oceans and avoid further degradation. They are also sites for scientific study and can generate income through tourism and sustainable fishing. MPAs provide a range of benefits for fisheries, local economies and the marine environment.
South Africa is very fortunate that all of its coral reefs are situated within MPAs. However, there has been limited research conducted on the affects of human activities in the different MPA zones. Do these activities influence the fish communities and if so, to what extent?
For the past three years a PhD study was conducted by Camilla Floros from the Oceanographic Research Institute to assess whether there were differences in the fish communities on reefs in the different MPA zones. The overall aim was to compare the fish communities on sanctuary reefs where there are theoretically no human activities to reefs that experience varying levels of human activities i.e. fishing and diving. The study included all the reefs at Sodwana (excluding Five-mile), Rabbit Rock in the north and the two sanctuary reefs in the south. Fish communities were assessed using underwater visual census techniques.
The results indicate that human activities are having an influence on the fish communities. The sanctuary reefs were recorded to have higher abundances of fish and greater biomass (average fish length) of predators. Predators such as kingfish and green jobfish are targeted by fisherman and consequently these species are expected to have lower abundances on reefs open to fishing. Such results were found on Seven and Nine-mile reef where fishing is permitted. However, two other important predator species, the potato bass and twinspot snapper, also had lower abundances on the Sodwana reefs compared to the sanctuary reefs. These two species are protected from fishing at Sodwana and it is unclear why their abundances are lower on these reefs. Fish communities are highly variable and there are numerous questions that arose during this study. The baseline data collected during this study will hopefully aid in addressing those questions and generate future research.
Two things are clear from this study; 1) South Africa’s coral reefs are unique because they are subtropical reefs yet support a high diversity and abundance of Indo-Pacific fish species compared to many other reefs in the Western Indian Ocean, and 2) the sanctuary reefs represent undisturbed ecosystems and should remain no-take and no access zones in light of the global pressures that affect coral reefs.
By Camilla Floros