A new study finds that more than 70 percent of these protected zones are exposed to high levels of wastewater pollutants, making corals and other marine life more vulnerable to climate change.By Teresa TomassoniMarine protected areas are designed to conserve coral reefs and other ocean ecosystems by restricting human activity within their boundaries. But most don’t account for one of the most severe and widespread threats to marine life that originates on land: sewage.