Research Focus...coral reefs
When describing coral reefs, only superlatives will do: they are the richest marine habitat, the biggest living structures (some are visible from space), the oldest ecosystem on earth, and one of the most beautiful and colourful habitats known.
The list is endless. Unfortunately, superlatives are also called for when describing the global status of reefs, as they are the most threatened marine habitat, facing a suite of threats ranging from global climate change to destructive fishing practices.
The International Coral Reef Initiative (ICRI) has designated 2008 as the International Year of the Reef. This worldwide campaign aims to raise awareness of the importance of reefs and the threats to their future. The ultimate goal of this initiative is to motivate people to take action to protect reefs.
What are coral reefs?
Corals are animals that belong to the same group as jellyfish and sea anemones, the Cnidarians. Each individual coral animal is called a polyp; polyps typically live in colonies. Corals fall into two main groups - soft corals and hard or ‘reef-building' corals. Hard corals are found in tropical and subtropical waters. They build calcium carbonate (limestone) exoskeletons which accumulate over time to form a reef. Coral reefs form massive, complex habitats for thousands of other species and are sometimes dubbed the ‘rainforests of the oceans' in reference to their staggeringly rich biodiversity.
The polyps of reef-building corals contain single-celled algae known as zooxanthellae; the algae and coral have evolved a symbiotic relationship - one that benefits both the algae and the polyp. The algal cell carries out photosynthesis and produces excess nutrients that are used by the coral; in fact, around 90 per cent of a coral polyp's nutrients are obtained from the algal cell. This relationship allows corals to grow much faster than they would be able to otherwise.
Importance of reefs
In addition to providing a home to thousands of other species of plants and animals and representing one of the most biologically rich habitats in the world, coral reefs are important as they provide many economic and environmental goods and services. An estimated 500 million people around the world rely on coral reefs for their livelihoods and food.
Their beauty and diversity makes coral reefs important tourist attractions. Sustainable tourism brings in money to local communities and creates jobs. Reefs are essential to local fisheries and they also provide coastlines with a natural protective barrier to wave action, erosion, storms and tsunamis.
Threats to reefs
Although coral reefs have survived for tens of thousands of years, they are currently in crisis as a result of long-term global changes combined with local-scale human-induced stresses. Roughly one quarter of all reefs are considered to be irreparably damaged, with a further two-thirds at serious risk.
Overfishing disturbs the natural balance of the myriad complex ecological interactions between reef species that have taken thousands of years to develop. Such an imbalance can result in unpredictable outcomes, such as a boom in the growth of seaweeds which can then smother the reef and result in coral death. Destructive fishing practices like dynamite or cyanide fishing are also highly damaging to reef structures and the species they support.
Reefs are being poisoned by pollution from urban and industrial waste, oil pollution, sewage and agrochemical run-off. Sedimentation from mining, logging, farming and construction can cover corals and smother them by blocking out the light required by zooxanthellae for photosynthesis. The destruction of coastal mangrove forests compounds the problem of sedimentation, as intact mangroves trap large amounts of sediment. Once the mangrove forests are removed or damaged, however, the sediment is deposited directly onto coral reefs.
Other threats include coral mining, a highly destructive practice that involves the removal of live coral to be used in construction and road building. Corals are also widely sold as curios and in jewellery. Unsustainable tourism is a large problem around the world, with boats dropping anchors on reefs, or divers touching, breaking or collecting coral.
Climate change poses a serious threat to coral reefs, as corals can only tolerate certain temperature limits. When sea temperatures rise, corals are subjected to coral bleaching, in which they expel their symbiotic zooxanthellae as a result of the stress induced by the heightened sea temperature; the colour is lost from the reef structure as a result, hence the term ‘bleaching'. Following a bleaching event, coral polyps typically die in large numbers. Climate change also poses a threat as increased carbon dioxide in the air affects the chemistry of the sea, causing an increase in the acidity of the seawater; this reduces the ability of corals and other marine invertebrates to build their limestone skeletons.
Earthwatch reef projects
Earthwatch supports a number of projects that enable volunteers to take part in reef research, working alongside top reef researchers and in-country NGOs to increase understanding of the status of reefs, the threats facing them, and to gather information to inform their conservation management.
In Belize, Earthwatch works with two local NGOs, Toledo Institute for Development and Environment (TIDE) and Toledo Association for Sustainable Tourism and Empowerment (TASTE) on the expeditions Coastal Ecology of Port Honduras and Coastal Ecology of the Sapodilla Cayes, respectively. Both expedition sites are located on the outstanding Meso-American Barrier Reef World Heritage site, the second largest reef in the world after the Great Barrier Reef in Australia.
Coastal Ecology of Port Honduras aims to develop a long-term monitoring programme for the Port Honduras Marine Reserve to develop short and long-term management plans for the reserve and to identify any emerging threats that may require action. The results from the 2007 field season indicate that the management of the various habitats in the reserve is having a positive effect, but that much more must be done for key species to recover. TIDE engages and involves the local community in the research and management of the reserve in a number of ways, including a community ranger scheme.
Coastal Ecology of the Sapodilla Cayes aims to monitor coral health, establish baseline data on the extent of coral bleaching in the reserve, record physical and biological features that may influence bleaching events, and develop a strategy to monitor and provide an early-warning system of future bleaching events.
Results from the 2007 field season have enabled the project team to develop a baseline on the status of the shallow reefs in Sapodilla Cayes Marine Reserve (SCMR). This will be important for a number of reasons: locally it gives managers a better idea as to the current status of the reefs in the SCMR and will allow them to better track changes in reef health. On a national and international level it is helping to improve knowledge about the impacts of global climate change and other factors influencing reef health. Within Belize, the SCMR has always been regarded as a site of high coral diversity, but also at high risk of degradation. The results will allow for improved monitoring and expand the knowledge about this critical ecosystem. TASTE hopes the data collected by Earthwatch volunteers will be directly used for improved management at a site and national level. To ensure management is directly addressing issues of sustainability and ecosystem health, it is necessary to have a complex understanding of the current status, and if possible past history, of the coral reefs.
This expedition, supported by the Mitsubishi Corporation, is located on Silhouette and Desroches Islands in the Seychelles. Volunteers work alongside Dr. David Smith (University of Essex and Director of the Coral Reef Research Unit), Dr. David Barnes (British Antarctic Survey, Cambridge University, UK), Dr. Richard Barnes (Cambridge University and Coral Reef Research Unit), Dr. Justin Gerlach (Nature Protection Trust of Seychelles and Cambridge University) and Dr. David Suggett (University of Essex, Coral Reef Research Unit).
The project is establishing the first baseline survey of the animals found in the intertidal zone. Coral surveys aim to record all species of coral and fish on the surrounding reef, and to understand the impact of the 1998 El Niño related bleaching event. Data gathered by Earthwatch volunteers have identified coral species that are tolerant and sensitive to bleaching. The tolerant species were less dependent on the photosynthesis of their symbiotic zooxanthellae and were able to adapt their metabolism. This fascinating information is critical for the future management of reefs in light of climate change.
Volunteers taking part in this expedition join scientists John Rollino, Garriet Smith (University of South Carolina at Aiken) and Thomas McGrath (Corning Community College) on San Salvador Island in the Bahamas to take part in the fourteenth year of this project, which aims to improve understanding of the reefs and the causes of coral afflictions. This is one of the longest-running coral research projects in the world and has documented two large-scale bleaching events (1995/1996 and 1998) and the subsequent mortality and recovery of the plants and animals that inhabit the reef. The project has also shed light on a range of emerging coral diseases.
Bahamian reef survey is also available as a teenager-only team.
Coral reefs of Southeast Asia are the most diverse on Earth and the most threatened of any region, with more than 80 per cent at risk from coastal development and fishing-related pressures.
Reef Check, a non-profit organisation, has been monitoring and surveying coral reefs around the world to provide baseline data to management organisations since 1996. Earthwatch volunteers on this expedition join Dr. Georg Heiss and Kim Obermeyer of Reef Check in the Gulf of Thailand and Andaman Sea, to gather long-term coral reef health data at several important sites around the country that lack any survey data, and to monitor the effects of marine protected areas and for signs of recovery from the 2004 tsunami. The information resulting from the project will allow government agencies and local communities to better manage and conserve these beautiful reefs. Reef Check also works with local communities to provide training in coral reef management and sustainability.
While much research has been carried out on growth, reproduction, mortality, and distribution of reef fish, relatively little is known about the role that parasites and disease play in their survival, and how a changing climate will affect these dynamics. Marine ecologists Paul Sikkel and Donna Nemeth are working on St. Thomas and St. John in the U.S. Virgin Islands, using Caribbean reef fishes such as surgeonfishes and damselfishes to explore host-parasite dynamics and their relationship to habitat. Sikkel and Nemeth work closely with local and federal agencies managing these reef systems.
This expedition is available as a teenager-only team
Truk Lagoon (Federated States of Micronesia) was an Imperial Japanese Naval base during World War II. In February 1944, the US and its allies began an intense aerial bombing campaign. More than 50 naval and merchant ships were sunk in Truk Lagoon, along with up to 100 aircraft. The submerged military remains attract colourful and diverse marine life, some of it unique to the area. Maritime archaeologist Bill Jeffery, materials scientist Dr. Ian Macleod, and marine ecologist Maria Beger aim to document and help protect Truk Lagoon's rich historic and biological heritage. The site is believed to be the world's largest group of artificial reefs, with significant marine ecology. Biological and archaeological surveys are combined in this fascinating multidisciplinary expedition. The results of the surveys will be used to identify priorities for biological and archaeological conservation.