Up until the 1990’s, ocean areas within Tonga were declared as open access for all Tongans, in the hopes of allowing everyone equal and fair sharing of its resources.
Over the years this caused a serious downfall in the status and health of the marine habitats, fish and invertebrate resources, that the communities heavily rely on for both subsistence and commercial activities. Coupled with increasing populations, land based pollution, run off, impacts from cyclones and storms, habitat destruction, the increasing threat of climate change and the rapid development of the coastal areas. The marine habitats suffered greatly, in some areas in Vava’u were reduced to less than 10% coral cover.
Marine habitats such as coral reefs, mangroves and seagrass all play an important ecological benefit to the marine resources offering habitat, food and shelter for the reef fish and invertebrates. Reef builders are the important component, these hard corals and coral building algaes (crustose coraline algae) are the developers of the coral reefs with secondary lesser benefits provided by soft corals, sponges and seagrass. Both live hard coral cover and species diversity of hard corals are needed for a reef to provide multiple ecosystem services.
With weakend coral reefs, the overfishing of important ecological species such as groupers, snappers, emperorfish and other high carnivores and piscivores, as well as roving herbivores such as parrotfish and surgeonfish, can create a more dominant algae shift on the coral reefs. These fish are also the important species for human consumption causing a downward shift in fishing potential.
Many macro algaes alongside turf algae and cyanobacteria are reef competitors, meaning they can take over coral reefs, smothering the ability for the corals to photosynthesise and feed.
For coral reefs to survive, develop and to have larval recruitment of corals, the impacts have to be reduced. Ecosystems and species are heavily intertwined, and each species has its role.
When the ecosystem balance shifts from continuing impacts, dominance of lesser ecologically important species takes over, causing further inbalance in the coral reefs. This not only ecologically affects the coral reefs but also impacts the other services that are provided including food sources for consumption, domestic economic benefits, tourism benefits and providing shelter from waves.
Its not all doom and gloom though, Tonga and Vava’u are making important decisions in the management of their near-shore resources. We will talk more about this in the upcoming weeks as well as other important ocean information!