To commemorate World Wildlife Day in 2020, take a look at 14 species that are key to their ecosystems and face endangerment from human activity, including…
SEA TURTLES: These marine reptiles are some of the oldest creatures on Earth, and can be found around the world in tropical and subtropical areas. Though they lay their eggs in sandy coastal areas, they spend their entire lives at sea, feeding on seagrass and foraging in coral reefs. Demand for their eggs, meat, skin, and shells has led to a rapid decline in their populations. Sea turtles are also threatened by coastal development and human disruption of nesting sites, becoming bycatch in fishing nets and lines, mistaking plastic pollution for food, and global warming.
CRUSTACEANS: These creatures with exoskeletons are some of the oldest animals on Earth. More than 50,000 known species can be found in fresh and saltwater habitats, playing an important role as food sources for marine animals, recycling nutrients as filter feeders, and decomposing dead organisms. Crustaceans are also economically important: blue crabs in the Chesapeake Bay of the U.S. generated an estimated $78 million in 2009 alone. They are threatened by ocean acidification which weakens their shells, loss of habitat on coral reefs, overfishing, and plastic pollution — ingesting microplastics that can travel up through the food chain.
SHARKS: Humans are the greatest threat to these apex predators, which have no known marine predators. Sharks maintain the balance of marine populations below them in the food chain. Without sharks, mid-level species would overconsume creatures at the bottom of the food chain. It can also affect human food supply: when sharks disappear, fish stocks that humans rely on for industry also collapse. Between 2000 and 2010, some 100 million sharks were killed annually — many hunted for their meat and fins or caught by trawling boats as bycatch. Climate change alters their habitats, affecting their ability to reproduce and find food.
FISH: There are an estimated 32,000 different species of fish worldwide, 33 percent of which are being fished at unsustainable levels. Overfishing is a destabilizing force in marine ecosystems that affects the entire aquatic food web. Fish are also an economic driver, with some 120 million people dependent on these species for their incomes. Climate change disrupts their migration, reduces their sizes and threatens the reefs and other habitats that they shelter in. Pollution is also a major threat, with chemicals, waste, fertilizer and oil spills causing harm to fish populations and affecting the seafood that humans eat.
WHALES: These marine mammals are facing steep population declines worldwide. Their role in ocean ecosystems is complex: they recycle nutrients by feeding at lower depths and releasing them near the surface, and become food for bottom-dwelling species when they die and sink to the ocean floor. Their dung provides nutrients for photosynthesizing plankton — scientists estimate that nearly half of the oxygen we breathe comes from this process. These creatures are believed to possess intelligence comparable to humans, with social organization, empathy, speech, and knowledge-sharing. Whales are threatened by water and noise pollution, becoming entangled in commercial fishing equipment, commercial hunting, collisions with watercraft and climate change.
CORAL REEFS: These tropical and subtropical features, found in the Atlantic, Pacific and Indian oceans, are home to more than a quarter of the planet’s marine life — and have a key role for eco-tourism and fisheries. They are threatened by ocean acidification from climate change; pollution from sunscreens, agriculture, sewage and chemicals; coastal development; overfishing; and tourism-related destruction from stepping and anchoring on reefs. Twenty-five percent of reefs around the world are considered damaged beyond repair, and close to 65 percent are under serious threat.
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