Key Largo , Florida ( CNN ) -- It was more than 40 years ago , but Ken Nedimyer still remembers the first time he went diving in the Florida Keys . `` It was just the most magical place I 'd ever been to , '' said Nedimyer , 56 . `` The coral reefs were so pretty . So many fish and so many neat things to see . '' Nedimyer became a commercial fisherman and tropical fish collector , working in the ocean nearly every day of the year . But by the mid-1980s , he noticed a troubling trend . Two of the region 's most important corals , staghorn and elkhorn , were in drastic decline . The corals -- tiny , stationary marine animals that make up the reefs -- were dying because of many reasons , including climate change , pollution and overfishing , experts said . Today , they 're on the endangered species list . `` The coral reefs of the Florida Keys are the most threatened and the heaviest-used coral reefs in the world , '' said Billy Causey , southeast regional director of the National Marine Sanctuaries , an entity of the National Oceanic and Atmospheric Administration . Reefs are often referred to as the rainforests of the sea . They attract more marine life than anywhere else in the ocean because of the natural shelter they provide . But they 're declining worldwide , not just in Florida , and some scientists fear that they could all be gone by 2050 . `` Coral reefs provide protection for our coastal areas , habitat for fish and recreational opportunities for millions and millions of people , '' Nedimyer said . `` It 's very important to protect that whole ecosystem . '' Reefs also have great economic value . Many people around the world depend on fisheries and the ocean for their livelihood . In the Florida Keys alone , more than 50 percent of the local economy is connected to a healthy marine environment . `` If coral reefs died completely , entire economies would be disrupted , '' Nedimyer said . As Nedimyer saw reefs die over the years , he became very concerned . `` It became a consuming passion ( for me ) to try to find ways to protect and restore coral reefs , '' he said . That passion led to Nedimyer starting the Coral Restoration Foundation , which has grown more than 25,000 staghorn and elkhorn corals in underwater nurseries . He and his staff of volunteers work three days a week maintaining the nurseries just off Key Largo . The nurseries cover more than an acre of the ocean floor . `` Ken 's coral nursery is the largest in the wider Caribbean , '' Causey said . `` It 's probably 10 times larger than any others that I know of . '' Do you know a hero ? Nominations are open for 2012 CNN Heroes . Nedimyer 's methods for growing corals have evolved over the years , but they 're all simple , easily duplicated and can be taught to anyone who can dive , he said . After the corals spend about a year growing in the nursery , they are transplanted to a reef in the wild . The goal is to get them to reproduce on their own and repopulate an area where they no longer exist . `` We 've been able to recreate one of the biggest thickets in the Florida Keys of staghorn coral , and that 's something we can duplicate throughout the Keys and throughout the Caribbean , '' Nedimyer said . Through education and awareness , Nedimyer has built a community committed to bringing coral reefs back to the Keys . His organization often collaborates with other groups , including the NOAA and the Nature Conservancy , a nonprofit conservation group . Nedimyer also spends a lot of time showing high school students his methods and working with them at his nurseries . `` This is n't just about me , '' Nedimyer emphasized . `` It 's about engaging a lot of people and training people , and I think it has a lot of hope . '' The impact is already noticeable in areas where corals have been transplanted . Fish and other marine life are starting to come back , and Nedimyer is hopeful that in time , the Keys ' ecosystem will recover . `` Most people think coral takes forever to grow , but some of these corals grow really fast , '' he said . `` They grow fast enough that we could make a big difference in a lifetime or less . '' Nedimyer 's most ambitious project is just ahead . Within the next five years , the Coral Restoration Foundation plans to grow and transplant 50,000 corals in the Keys , which he says is the largest effort of its kind in Florida and the Caribbean . `` Before , I felt helpless watching corals die , '' Nedimyer said . `` Now I think there 's a way for everybody to get involved . There 's hope . '' Want to get involved ? Check out the Coral Restoration Foundation website at www.coralrestoration.org and see how to help .
Ken Nedimyer is helping to restore dying coral reefs in the Florida Keys . He and his group are growing coral in nurseries before transplanting them to the wild . Hide Caption 1 of 6 Photos:Coral reef restoration efforts around world Coral reefs are critical to marine life , many economies . Do you know a hero ? Nominations are open for 2012 CNN Heroes .