Ocean ecosystems have already experienced the collapse of regional fisheries, notably the overexploitation of cod fisheries in the northern Atlantic Ocean. Oceans contain over 80 percent of life on earth. Unfortunately, according to the Worldwide Fund for Nature, approximately 90 percent of the world's large fish have been fished out, with over 70 percent of the world's fisheries either fully exploited or overexploited. Without changes to fishing practices, fisheries of most food species are expected to collapse by 2050.
Coral reefs are unique, biologically diverse ocean ecosystems. Coral reefs are extremely sensitive to environmental changes, pollution, overfishing and invasive species. Currently, over half of the planet's coral reefs are threatened, including the Great Barrier Reef in Australia, reefs in Hawaii, Jamaica, Virgin Islands, and many reefs throughout Indonesia, India and Africa. In many locations, fishing practices using explosives and cyanide hasten the destructive process. Global warming is a growing threat, as many reefs will be unable to survive warmer water temperatures.
Worldwide, thousands of acres of rainforest are cut down every hour, and 93,000 square miles each year, mostly due to logging activities and to clear land for agriculture. Over half of all species of land animals live in rainforest. Rainforest covered approximately 14 percent of the planet at the dawn of civilization; currently, only two percent of the Earth is rainforest. Destruction of this biologically rich ecosystem represents a massive and irretrievable loss of much of the world's biodiversity.
Defenders of Wildlife identified 21 endangered ecosystems that represent some of the most unique and biologically diverse ecologies in the United States. Large streams and rivers throughout the lower 48 states and Hawai'i are threatened by dams, overharvesting of water and pollution, with more than 80 percent of river fish communities degraded. Old growth forests throughout the country are in trouble, including the majestic redwood forests of the northwest. The nation's wetlands have been dramatically reduced in size, drained for agriculture or residential development.