Nature-based nutrient reduction for seagrass restoration

Abstract

Seagrasses provide the following benefits worldwide. ● Habitat for Marine Life ● Ocean Acidification Control ● Nursery for Juvenile Fish ● Oxygen Production ● Food ● Sediment Erosion Control ● Biodiversity ● Nutrient Cycling ● Carbon Storage (Blue Carbon) Seagrass loss has been persistent for the past 100 years and is now accelerating at 7 percent (21,000 square kilometers) per year. We are addressing seagrass loss resulting from nutrient pollution which is about one third of the total. The technical objective is to remove at least as much total nitrogen from the sediment and bottom waters to allow restoration with the subsequent successful planting of seeds from nearby meadows. Our nature-based process starts with the eutrophication-induced restriction on the process to remove excess nitrogen from the top layer of sediment, coupled nitrification denitrification (CND). Decaying organic matter and biogeochemical processes consume enough oxygen to reduce the efficiency and capacity of the CND process. The solution is to increase the rate of dissolved oxygen flux in the bottom waters. Although science has known this for 20 years, how to do it has been a mystery. To facilitate oxygen dissolution, we will use nanoscale oxygen bubbles mixed with bottom water and delivered to the water/sediment interface.