They are the producers present in the aquatic ecosystem. Phytoplankton is the plant like organisms of the water that carry outphotosynthesis and float in the upper areas of the world’s ocean. Phytoplankton, also known as microalgae, are similar to terrestrial plants in that they contain chlorophyll to capture sunlight, and they use photosynthesis to turn it into chemical energy in order to live and grow. Phytoplankton is responsible for most of the transfer of carbon in the carbon dioxide from the atmosphere to the ocean. Worldwide, this “biological carbon pump” transfers about 10 gigatonnes of carbon from the atmosphere to the deep ocean each year. Even smallchanges in the growth of phytoplankton may affect atmospheric carbon dioxide concentrations, which would feed back to global surface temperatures.

A wide variety of adaptations help them stay afloat. Some have their flagellas, fins and spines that act as water wings. Some othersstore extra food as oil, which buoys them up near the surface. When phytoplankton becomes full of oil, they die and sink to the bottom. They become buried under mud and sand. Over millions of years, heat and pressure within the earth transforms the oil from the algae into crude-oil deposits that can later be used by humans. During normal years, the Earth’s oceans go through a process known asupwelling in which the easterly winds blow across the equator and drag the warm surface water with them. Then the denser, colder water from the depths of the ocean rises, restoring oxygen and allowing mineral nutrients to return to the surface where phytoplankton can use them once again.

The two main classes of phytoplankton are Diatoms and Dinoflagellates. When too many nutrients are available, dinoflagellates can bloom or explosively grow to huge numbers and form harmful algal blooms, these blooms can produce extremely powerful bio-toxincompounds that can kill marine life and people who eat contaminated sea food and results in Red tide. Diatoms are dominant members of the phytoplankton, they are especially common in temperate, coastal and polar regions. Dinoflagellates are found throughout the world’s oceans, but tend to prefer warmer areas.