Photosynthesis in the ocean is the infrastructure upon which complex webs of marine life are built. The hydrocarbon structures made by photoautotrophs are the base of most food webs, the oxygen they produce makes water livable for aerobes like fish crabs and mollusks, and carbon dioxide they consume moderates sea pH and temperature. In oceanography, photosynthesis has been widely studied and is recognized as an important process. However, relatively little is known about the photosynthetic activity of microalgae adapted to living on the seafloor. These algae are of particular importance as they could be a critical source of oxygen and organic matter to benthic communities, and they may be a major sink for carbon dioxide in the world ocean.
The focus of my work is the oxygen production done by microalgae, mostly diatoms (fig. 1) and cyanobacteria, on permeable sands on the seafloor of the continental shelf off Florida’s Big Bend region in the Gulf of Mexico. This region is important to this research because it is an exceptionally broad area of shelf comprised of seafloor exposed to sunlight able to support photosynthesis. My field sites are 3 stations along a transect line that goes 18 miles off the coast from FSU’s Coastal and Marine Laboratory (fig. 2). The shallowest site is 5m deep, the next is 10m deep, and the deepest site is 18m deep. The sites represent not only increasing depth but an increasing distance from the shore and nutrient loading from estuaries.