FSU researchers find most nitrogen in Gulf of Mexico comes from coastal waters

Researchers from Florida State University discovered that almost all of the nitrogen used to fertilize the Gulf of Mexico's open ocean is transported into the gulf by nitrogen from the coasts.Nature Communications published the work. It is essential to understand the food web of the ecosystem. This is where many commercially important species of fish spawn, including the Atlantic Bluefin Tuna, which was the focus of the research.Michael Stukel, associate professor in the Department of Earth, Ocean and Atmospheric Science and co-author of this paper, stated that the open-ocean Gulf of Mexico was important for many reasons. It's an ocean desert with few predators that threaten larvae. This is why it's a good spawning ground to several species of mahi-mahi and tuna. You will find many other organisms out there in the open ocean.Phytoplankton is the foundation of the food web in Gulf of Mexico, which supports new larvae and other organisms. Like plants on the ground, phytoplankton needs sunlight to grow. Researchers wanted to find out how nitrogen was getting into the gulf.A few hypotheses were considered. The first was that nitrogen might have come from the deep sea. Another possibility was that the larvae were being supplied by a phytoplankton called a nitrogen fixer. They also considered the possibility that nitrogen could be entering the ocean from the coast's shallower regions.They combined measurements taken at sea during research cruises in 2017- 2018 with data from satellite observations and models to find that organic matter from the coasts accounts for more than 90% of the nitrogen entering the open ocean in the Gulf.Scientists knew from the beginning that large, swirling currents act as slow-moving storms in oceans and move water from the coast to the interior of the Gulf. Researchers believe that the nitrogen is likely to be moved by those eddies. However, they did not answer this question in their study.Climate change has an impact on how water at the surface and deeper waters mix. It is difficult to understand how climate change will impact these lateral currents.This is an important aspect of the ecosystem because it's crucial to understand. Currents that connect coastal areas with the nutrient-poor open sea are key to the survival of larval fish species like tuna and other species found in the open-ocean Gulf of Mexico."If we are to understand how the ecosystem will react to climate change in the future, we must understand how all of these lateral transportations work within the ocean," Stukel stated. Scientists who study biogeochemical balances, especially those that are enclosed by productive coastlines like the Gulf of Mexico, should be aware of how lateral transport impacts these ecosystems.###Thomas Kelly, a recently graduated FSU doctoral candidate, led this work. The National Oceanic and Atmospheric Association and the National Science Foundation supported this work. This study was co-authored by researchers from Scripps Institution of Ocology and University of Hawaii at Manoa.