Garbage that is dumped or washed into the sea poses a major threat to ocean health worldwide. Wildlife often become entangled in abandoned fishing gear or mistake trash—particularly plastic—for food. In the Pacific Ocean, scientists are studying an area the size of Texas that has become laden with floating garbage, especially plastic pieces from items like bottles, bags, fishing floats, and cigarette lighters.
Mangroves, salt-tolerant trees that thrive in swampy areas along many tropical and subtropical coasts, are rapidly being displaced by development, industrial activity, and aquaculture. Normally, their dense forest canopy and extensive root systems provide many benefits to humans and wildlife. But if current trends continue, scientists believe that mangroves could disappear completely within a century.
Among the biggest threats to ecosystems near the poles, including the Arctic and Southern Oceans, is rapid climate change. As greenhouse gasses trap more of the sun's heat, the waters are warming and becoming more acidic, sea ice is melting, and native communities are struggling with unpredictable weather and hunting seasons.
The deep ocean fish known as orange roughy became a popular seafood item during the 1980's. Because we did not understand the fish's slow reproductive cycle when heavy fishing began, we have overharvested orange roughy, and stocks have declined rapidly. This stands in contrast to another deep ocean species called sablefish, which is well studied and managed sustainably.
Scientists found the rapa whelk, a sea snail native to Asia, in the Chesapeake Bay in 1998. It probably arrived as larvae in a ship's ballast water and has now established a population in the bay that poses a serious threat to the Chesapeake clam fishery. The invading snail may also compete for food with the native species, such as knobbed and channeled whelks.
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