2 . Scientists often compare coral reefs(珊瑚礁) to underwater rainforests, yet unlike the leafy plant base of a forest, corals are animals. The soft creatures are naturally half-transparent and get their brilliant color from algae(藻类) living inside them. When corals experience stress from hot temperatures or pollution, they halt the interdependent relationship with algae, typically pushing them out and turning white. Corals are still alive when they are white, but they're at risk and many eventually die, turning dark brown.

Scientists around the world are looking for means to protect and maybe increase corals. One common option is to create more protected areas — essentially national parks in the ocean. Beyond nature preserves, some conservationists are looking to more hands-on methods. One research center in the Florida Keys is exploring a form of natural selection to keep corals remaining. The reef system in the Keys has been hit hard by climate change and pollution, which is especially tough, because corals there help support fisheries worth $ 100 million every year.

To keep the wild ecosystem alive, Erinn Muller, the center's director, and her team are harvesting samples of the corals that survived the environmental stress naturally, keeping them to make them reproduce, and then reattaching them to the reef. They have 46,000 corals on plastic frames under the sea. So far, the center has regrown over 70,000 corals from five different species on damaged reefs.

In The Bahamas, Ross Cunning, a research biologist at Chicago's Shedd Aquarium, focuses on corals with genes that could make them natural candidates for restoration projects. He published a study of two Bahamian reefs, one that survived an extreme 2015 heat wave, and one that didn't. "We think their ability to deal with these higher temperatures is built into their genes," says Cunning. There's evidence of corals evolving more quickly to resist rapidly warming climate. The big question scientists need investigate, adds Gunning, is how much more heat corals can adapt to.

4 . About 12 million tons of plastic wastes are entering the oceans every year. This garbage pollutes the water, kills wildlife and breaks down into small pieces that fish and other creatures eat.

Now a group of Spanish fishermen will receive economic support to catch plastics. It is part of a new project. Carlos Martin is one of the fishermen taking part in the project. He and his partners collect the plastic in the ocean and bring it back to land every week. Martin thinks rivers carry a lot of plastics to the sea. He says his most concern is no more than that the plastics often get caught in the nets, which makes nets not work properly. They take on mud（泥）, causing the nets to break because they weigh so much.

Under the new programs, one million pounds will support ocean cleanup efforts for fishermen like Martin. The money is coming from the European Union and the Catalan government. Sergi Tudela, the General Director of Catalonia Fisheries, is responsible for the cleanup project. He said, "We are hopeful that if we are successful in this project, we can apply it to other areas in the Mediterranean（地中海）."

Government reports show that the amount of plastic wastes washing up along the Spanish coastline has grown by 65 percent in just six years. Fishing equipment makes up a large part of the about 8 to 12 million tons of plastics left in the world's oceans every year.

Martin says the fishing community now understands how big the problem is. He says, "In the past we didn't see it that way. We took the plastic garbage and threw it back into the water. I think that after a few year here we have realized the problem. Nothing is thrown into the water; we collect everything and bring it to shore.