Case Study: Phytoplankton

What is phytoplankton?

• Phytoplankton are plant organisms that live in the water and which produce organic compounds from inorganic molecules through the process of photosynthesis. Essentially, these organisms acts like land plants by producing oxygen and absorbing carbon dioxide (http://www.sciencedaily.com/articles/p/phytoplankton.htm).
• Sunlight is crucial to phytoplankton's production of oxygen (through the process of photosynthesis), therefore these organisms live in the surface waters of oceans and lakes, in both fresh and salt waters (http://earthobservatory.nasa.gov/Features/Phytoplankton/).
• Phytoplankton are vital to the food web in all water environments/ ecosystems; they are the base of the food chain for aquatic animals ranging from microscopic zooplankton to some of the largest whales in the oceans.

- Responsible for much of oxygen present in Earth’s atmosphere (1/2 of total amount produced by all plant life)
- Slowly declining annual numbers of about 1% per year in total population
- As of 2010 is equivalent to a 40% decrease in population since 1950
- Growth depends on amount of CO2, sunlight, and nutrients. (nitrate, phosphate, silicate, and calcium at various levels.... water temp?... water depth, wind, and predators)
- Life span = a few days
What chain reaction would result from the decline of phytoplankton in the world?
-A decline in phytoplankton in the Earth’s waters would greatly affect larger systems in our world. Not only would a large portion of the base of the food chain decline, but so too would a vast amount of carbon dioxide absorption and oxygen production.
- Because phytoplankton are at the base of the food chain in the ocean environment, a decline in their existence would severely affect the rest of the food chain, including humans (http://www.sciencedaily.com/releases/2010/07/100728131705.htm).
- Whales and small fish eat plankton... Then, bigger fish eat smaller fish etc.
- Chain continues on to humans eventually (we eat fish)
- Without plankton smaller fish and crustaceans would be out of a food source and die causing a linear chain reaction of death and extinction of bigger fish and other mammals
- Ozone layer contribute to decline? Yes, by not absorbing all of the radiation and UV rays it kills off plankton because plankton are sensitive to the sun’s radiation
How would this effect the supply of oxygen on the Earth?

• Plankton takes in Carbon Dioxide and gives off Oxygen (previously said) during their process of respiration, which they contribute for HALF of Earth’s oxygen in it’s atmosphere, directly affecting the survival of all living things on Earth.
• A HUGE loss of oxygen in the atmosphere would be felt. An increase in Carbon Dioxide, which would cause an increase in temperature, causing a chain reaction of events leading to the struggle of survival of many of the Earth’s food chains.
• If a drastic decline in plankton, there will be more CO2 in the air and less oxygen, meaning hotter temperatures. Resulting in contributions to global warming.