Declining coral abundance is often accompanied by an increase in another benthic organism that is better adapted to cope with environmental shifts and habitat degradation. Regime shifts are best known from studies in the Caribbean where algae have become dominant on reefs once dominated by corals. In the Wakatobi however, the Sampela reef system has seen an increase in sponge densities over the past ten years and a decrease in live coral cover of approximately 20%. The increase in sponge densities is driven by one phototrophic sponge, Lamellodysedia herbacea, but it also has a large population of the giant barrel sponge, Xestospongia testudinaria. Recent experimental evidence has shown that sponges appear much more resilient to ocean warming and acidification than coral, so are likely to be a greater feature of coral reefs in the future. Dissertation projects in this area will build on long-term datasets to track sponge assemblages on sites around the Hoga/ Kaledupa channel. Projects investigating the feeding behaviour of spongivorous fish will help to ascertain the role of predation on controlling sponge populations. Other projects will investigate competitive interactions between corals and sponges as sponges are known to utilise chemical warfare and direct overgrowth as competitive strategies. Greater effort is needed to understand the interactions between corals and sponge and the consequences of sponge dominated systems for coral reef biodiversity. Research activity will also allow us to explore the potential management interventions needed to prevent future regime shifts.
There is a triangle of reefs in Eastern Indonesia that have the highest diversity of hard coral genera, the proxy commonly used to assess overall diversity of coral reefs anywhere in the world. Both the marine research stations being used by the Opwall teams are in the centre of this triangle. The South Buton Marine Training and Research Centre has established a series of standard monitoring sites on reefs south of Bau Bau and around the surrounding small islands, with the objective being to use the data to develop plans for conserving these reefs. The Hoga Island Marine Research Station is located in the heart of the Wakatobi Marine National Park. Over the last 20 years, a series of scientists have been based at this site during the Opwall survey seasons and as a result, this is now the most published site in the Coral Triangle. For the last 14 years a series of constant monitoring sites around Hoga and eastern Kaledupa have been monitored for macroinvertebrates, fish communities, coral cover and community structure. The 2019 season will complete this monitoring plus some additional research projects.
The South Buton marine research centre opened in 2013 and has established a series of standard monitoring sites on reefs south of Bau Bau and around the adjacent islands. These are being monitored annually and it is hoped to use the data to demonstrate that a number of the reefs in this area are of high conservation value. Preliminary social studies have commenced as of 2017, involving interviewing fishermen and other local stakeholders to gauge areas of high fishing pressure and the preferred catch methods. The next step is then to begin implementing some conservation management strategies involving all of the local stakeholders in the near future. There is also a small team at this site working in collaboration with the Global Fin Print Project, which monitors shark and ray populations through the use of baited remote underwater video systems.
The Hoga Island marine research station is located in the heart of the Wakatobi Marine National Park. Over the last 20 years a series of scientists have been based at this site during the Opwall survey seasons and have built up the publications emanating from the site to a level which is unsurpassed by any other marine research site in the Coral Triangle. These data and publications have been used to promote the biodiversity value of the Wakatobi, raise its profile internationally and in particular enable it to be designated as a Biosphere Reserve. For the last 12 years a series of constant monitoring sites around Hoga and eastern Kaledupa have been monitored for fish communities, coral cover and community structure and macro-invertebrates. In addition annual fisheries monitoring is being completed to assess changes in the fisheries particularly as some of the management initiatives developed by Opwall (e.g. buy outs of fishing licences and carrageenan extraction) begin to hopefully have an impact. Alongside these long-term monitoring projects there are also newer projects such as a coral restoration program and seagrass monitoring to provide a wide range of opportunities to all.
At the marine sites during the day, the weather is normally sunny and warm (around 30 degrees Celsius), and the night temperatures drop to around 20-25 degrees Celsius. Being on the coast means there is often a pleasant breeze so it does not always feel this hot. It rains rarely, but when it does it tends to be very heavy for short periods of time.
Fitness level required
Low-Moderate. Some fitness is required for in water activities, but conditions are relatively easy.
Facilities on Hoga are comfortable, but very basic – the site has shared huts with beds and mattresses and a mandi style bathroom (squat toilet and bucket shower) attached. There is very limited cell phone signal which can usually only be used with an Indonesian SIM card and no Wifi access.