One group of creatures produces 70% of the earth's oxygen and also consumes carbon dioxide at an astonishing rate. They are phytoplankton, mostly microscopic, single-celled organisms.
Phytoplankton come in many shapes and forms. The majority are single-celled plants, but some are bacteria, and others are protists. Common types of phytoplankton are cyanobacteria, green algae, diatoms, dinoflagellates, and coccolithophores.
Phytoplankton play an essential role in human life in that they produce 70% of the oxygen we breathe, much more than terrestrial plants.
They are part of the carbon cycle, as they consume atmospheric carbon dioxide (CO2). CO2 resides naturally in the atmosphere, but human beings, mostly through the burning of fossil fuels, have released ever greater amounts into the atmosphere.
Along with CO2, phytoplankton need sunlight and other nutrients to survive.
Aside from providing oxygen, phytoplankton are a significant part of the food chain which includes everything from other tiny zooplankton to shrimp, fish, and whales.
At certain times, phytoplankton grow at an explosive rate for days or weeks, creating what is called a 'bloom.' These blooms may last several weeks, even though individual phytoplankton live for only a few days. Despite being microscopic individuals, phytoplankton blooms can be hundreds of square miles and seen from outer space.
Pollution can trigger an algae bloom. Such as when raw sewage is dumped into the local waters, a common occurrence in New York/New Jersey Harbor Estuary.
It sets off the process of eutrophication. Bacteria and other runoff stimulates the overgrowth of algae, these eventually die, and the bacteria eating the dead algae or plankton use up the oxygen in the water. Thereby creating hypoxia, the suffocation of other species living in the water.
Sometimes phytoplankton overgrowth can produce biotoxins, killing marine life and people who eat this marine life. 'Red tide' is a type of toxic algal bloom.
By providing most of our oxygen and being a major food source, these tiny creatures are indeed a fascinating link in the chain of life