The ocean is like a tapestry of interconnected relationships which require balance to thrive. This story starts with phytoplankton. Phytoplankton are microscopic algae (plants) that can only be seen individually under a microscope. Like terrestrial plants phytoplankton photosynthesise, taking in carbon dioxide and producing oxygen. 50% of the world’s oxygen supply comes from the respiration of phytoplankton. These little organisms are the basis of all life on earth. They provide food for tiny zooplankton, which in turn are the food source for most juvenile fish and for some of the largest creatures on the planet like the Blue Whale. Balance is key to a healthy ocean. Too much phytoplankton (also known as an algae bloom) causes murky water preventing other important species like seagrass to thrive. Seagrass is one of earths most efficient sequesters of atmospheric carbon dioxide with the ability to lock carbon away at a rate up to 35 times greater than the rainforest. Oysters feed on phytoplankton and filter the water continuously. One oyster filters about 190 litres of seawater a day which helps keep an algae bloom in check. The carbon absorbed by the plankton is used to build the oyster shells as the oysters feed. This locks the carbon away for hundreds of thousands of years. Simple, efficient, cool!
By feeding on phytoplankton, oysters also sequester nitrogen from the ocean that stems from water running off the land. In doing so, they process nitrous oxide which is a greenhouse gas 300 times more damaging to the Ozone layer than carbon dioxide.