Phytoplankton are some of Earth’s most critical organisms and so it is vital study and understand them. They generate about half the atmosphere’s oxygen, as much per year as all land plants. Phytoplankton also form the base of virtually every ocean food web. In short, they make most other ocean life possible.
Through photosynthesis these organisms transform inorganic carbon in the atmosphere and in seawater into organic compounds, making them an essential part of Earth’s carbon cycle. Because they take up carbon dioxide from the atmosphere, when they die they sink they carry this atmospheric carbon to the deep sea, making phytoplankton an important actor in the climate system. Phytoplankton growth is often limited by the scarcity of iron in the ocean. As a result, many people are discussing plans to fertilize large areas of the ocean with iron to promote phytoplankton blooms that would transfer more carbon from the atmosphere to the deep sea.
Harmful Algal Blooms
Phytoplankton have a direct impact humans and other animals. Dense blooms of some organisms can deplete oxygen in coastal waters, causing fish and shellfish to suffocate. Other species produce toxins that cause can cause illness or death among humans and even whales that are either exposed to the toxins or eat shellfish that accumulate toxins. Such harmful algal blooms (HABs) cause significant economic loss every year in the seafood industry and in tourist communities, and scientists are working to understand the causes of these blooms and to devise ways to predict and prevent them.