The amount of nitrogen fixed in the ocean is estimated to be around 100-150 million tons per year. This is a significant amount of nitrogen, and it is essential for the growth of marine plants and animals. Nitrogen fixation is a process that converts atmospheric nitrogen into ammonia, which can then be used by plants and animals. This process is carried out by bacteria that live in the ocean, and it is thought that these bacteria may be responsible for as much as half of the nitrogen that is fixed in the ocean.