While investigating the effects of climate change on nitrogen cycling in temperate coastal systems, Rhode Island researchers made the first scientific link between warming and fundamental changes in nutrient cycles. Researchers found that the observed estuary shifted from acting as a nitrogen filter to acting as a nitrogen source—which has a profoundly negative impact on marine ecological systems. Previously, when denitrification (removal of nitrogen) dominated the cycle, coastal marine sediments cleansed the water of excess nitrogen. When nitrogen fixation, the process of converting nitrogen into a biologically usable form of nitrogen (such as ammonium or nitrate), dominated the cycle, more nitrogen was brought into the system. Researchers discovered that the sediments added more than 1.5 times the amount of nitrogen from the land and atmosphere combined. If this process is happening in other places, the sediments can produce large amounts of nitrogen, which could have significant consequences for offshore systems. The investigator who led the research is now examining nitrogen cycling in the Louisiana wetlands to determine whether similar conditions exist.