Conserving Island & Coral Reef Biodiversity

Biodiversity has become a buzzword, largely because of our planet's extinction crisis, which is rapidly increasing the rate of species loss. But while every continent has many endangered plants and animals, the majority of these extinctions have taken place on the world's islands. Over the past 400 years, since records have been kept, more than half of all animal extinctions have occurred on islands, which cover only 5 percent of the Earth's land surface.

Why are islands the sites of so many extinctions? Islands are centers of biodiversity, and many island species are particularly sensitive to change. The geographic isolation of islands allows species to evolve with fewer competitors and predators resulting in endemic species—or highly unique plants and animals found nowhere else on earth—such as Madagascar's lemurs.

Not only are islands home to endemic species, but they contain some of the world's richest ecosystems.

Many islands in the tropics are island chains formed from coral reefs that encircle a lagoon. These reefs are teeming with biodiversity; covering less than 1 percent of the Earth's surface, they are home to at least one third of marine species. But coral reefs are also one of the most endangered habitats, putting the thousands of species they harbor at risk as well.

Today, coral reefs face multipronged threats to their biodiversity:

  • Pollution permeates the oceans. Exhaust from ships, discarded plastics and chemical runoff from fertilizers, pesticides and industry waste create toxic conditions. Large wastes, like plastic, can choke or entangle birds and fish, while chemical emissions from exhaust and land effluents are just as dangerous to marine life as they would be for humans to breathe or drink. Excessive nitrogen and other chemicals from fertilizer runoff can cause algal blooms (rapid growth of algae), which can cloud waters and prevent corals, seaweed and other species from receiving adequate sunlight.

  • Overfishing of the oceans wreaks havoc on coral reefs and other marine ecosystems. Large predators like tuna, sharks and swordfish have become dangerously overfished, disrupting the carefully balanced food chain of the marine ecosystem. The depletion of these larger species causes the mid-sized fish on which they prey to explode in number, which in turn diminish the populations of smaller prey. Since many coral reefs are close to land, their rich biodiversity is an easy target for fishermen; many reef ecosystems are severely disrupted by overfishing.

  • Climate change has also caused detrimental impacts to island and reef biodiversity. The rising waters caused by melting polar ice caps are putting many low-lying islands and coral reefs in danger. Usually found in shallow waters, reefs can be impacted by the changes in temperature, water composition and amount of sunlight caused by even slight changes in water level. Many scientists now believe that climate change will bring with it increasingly intense flooding and storms, which will have disastrous impacts on the sensitive wildlife and ecosystems of islands and coral reefs.

  • Ocean acidification is another major effect of the greenhouse gases that cause climate change. Much of the carbon dioxide released by the burning of fossil fuels is absorbed by the oceans, but these pollutants have disrupted the normal pH balance of the oceans, creating increasingly acidic marine environments. Sensitive species like corals are unable to produce sufficiently strong skeletons in such toxic conditions, resulting in extremely weakened reefs. Similarly, many reef species that build calcium carbonate shells are unable to produce full shells in acidic waters, leaving them highly vulnerable to predators, pollution and other threats.

Twenty percent of the world's coral reefs have already been destroyed. At the current rate, all reefs could be gone by the end of this century. Equally sobering statistics describe the current state of the open oceans, rainforests, mangroves and many other natural habitats.
What can be done?

There are many different approaches that organizations are taking to try to mitigate these threats to island biodiversity and the world's coral reefs. Some organizations have taken the scientific approach, researching and collecting data to devise measures to help curb the effects of climate change, ocean acidification and pollution. Others are working to develop policies on both the national and international level to establish sanctuaries and enact regulatory measures for emissions, overfishing and pollution. Some have taken the hands-on approach, organizing beach cleanups, farming coral reefs and teaching environmental education programs. Seacology is applying yet another approach: working directly with the local communities that experience these environmental changes firsthand to create locally-managed marine and terrestrial reserves. Using a grassroots approach, Seacology collaborates with local interests to ensure protection of wildlife and ecosystems through the establishment of quality reserves.

One of Seacology's projects involves working to protect the Muri Coral Reef of Rarotonga, one of the Cook Islands. The island is surrounded by a lagoon, which is separated from the ocean by the island's many coral reefs. Rarotonga's famously picturesque coastline contains stretches of sandy beaches and beautiful palm trees, making them popular tourist destinations; however, in recent years increasing development and tourism have threatened the lagoon and coral reef.

The community members of Muri Village on Rarotonga wish to protect their local reef, lagoon and beaches against the many threats they face. At the same time, they desperately needed improvements to their community center, which serves numerous purposes including a cyclone evacuation site, cultural arts center, youth gymnasium and health clinic. Seacology stepped in to help them on both fronts, providing funding for the needed renovations in exchange for a commitment to set aside 413 acres of their lagoon and coral reef as a protected area, where harvesting of coral, mammals, birds and any nonsubsistence fishing is strictly prohibited. Seacology's direct collaboration with Muri Village is respectful of local needs and traditions while reaching a mutually beneficial outcome that protects their fragile coral reefs. Working with the local people ensures that the new reserve is truly protected—the locals are responsible for establishing and monitoring the reserve, and they have a vested interest in maintaining its integrity.
What Can You Do?

  • Dive responsibly. When exploring coral reefs and other marine ecosystems,don't remove shells or other items, and do not touch coral.

  • Fight climate change by lowering your carbon footprint with greener eating choices, transportation methods and purchasing habits.

  • Consume sustainable seafood. Lessen the effects of overfishing by making sustainable choices when you eat fish. See the Monterey Bay Aquarium's Seafood Watch Guide.

  • Support Seacology and other organizations that are working to protect the vibrant biodiversity of our oceans and terrestrial environments. A little bit goes a long way; for example, with Seacology's Save an Acre program, you can save one acre of the Muri coral reef for just $40.
About Seacology
Seacology has over 200 projects like the Muri Reef Conservation project on 116 islands in 45 nations around the planet. It is this grassroots approach that can ensure sensitive ecosystems with rich biodiversity like coral reefs survive for future generations. Learn more at