Friday 11 July, 2008
Coral Reefs - the Rainforests of the Oceans
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 facing their future. The ultimate goal of this initiative is to motivate people to take action to protect 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 most colourful habitats known.
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.
What are coral reefs? Corals are animals and 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. Coral fall into two main groups, soft corals and hard or ‘reef-building’ corals. Hard corals are found in tropical and subtropical waters and 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 called zooxanthellae; the algae and the coral have evolved a symbiotic relationship – a relationship 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% of a coral polyp’s nutrients are obtained from the algal cell. This relationship allows corals to grow much faster than they would otherwise be able to.
Importance of reefsIn 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 and the goods and services that coral reefs provide have been valued at $375 billion per year.
Due to their beauty and diversity, coral reefs are important tourist attractions. Sustainable tourism brings in money to the local community and creates jobs. Reefs are essential to local fisheries and they also provide a natural protective barrier for coastlines from wave action, erosion, storms and tsunamis.
Threats to reefs Although coral reefs have survived for tens of thousands of years, they are currently in danger from global changes combined with 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 thousand of years to develop. Destructive fishing practices such as dynamite fishing and cyanide fishing are also highly damaging.
Reefs are being poisoned by pollution from urban and industrial waste, oil pollution, sewage and agrochemical run-off. 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 and careless tourism is a large problem around the world, with boats dropping anchors on reefs, 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. Following a bleaching event, coral polyps typically die in large numbers.
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 and threats facing them and to gather information to inform their conservation management.
Bahamian Reef Survey
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.
Reef Fish of the Virgin Islands
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.
Coral Reefs of Thailand
Coral reefs of Southeast Asia are the most diverse on Earth and are the most threatened of any region, with more than 80% 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 joining 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.
Diving World War Two Wrecks of Truk Lagoon
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.