Posted by admin | 07.02.2014 | Marine Science

Photosynthesis

Breathing is something we do every day. We inhale oxygen and exhale carbon dioxide; this is a process that sustains and regulates all life on earth. Over millions and millions of years, the biological processes of earth’s organisms helped to create a favorable atmosphere for large animals to flourish. This idea was coined the “Gaia Theory” by James Lovelock in the 1960s. Without life on earth, the atmosphere would contain only trace levels of oxygen, levels not suitable to sustain the species that exist today. While it is tempting to credit trees and other large plants for producing the oxygen we breathe, it is actually tiny microorganisms that are deserving of the credit.

About 2.4 billion years ago, before photosynthesis (the process of converting sunlight, carbon dioxide, and water into sugar and oxygen) evolved, the oceans and atmosphere were anaerobic, containing little or no free oxygen. As photosynthetic organisms evolved, the oceans began to fill with oxygen and this oxygen gradually transferred to the atmosphere. We must thank the bacteria, protozoa, and phytoplankton for the oxygen we breathe. Today, the majority of the oxygen in the earth’s atmosphere comes from these microorganisms.

These phytoplankton are responsible for the majority of primary production on earth. Primary production is the process of using carbon dioxide to produce organic matter. These organic compounds provide the necessary energy to sustain life higher up the food web including, large fish, birds, mammals, and people. Many of these primary producers are single celled plankton that colonize in the ocean to form seasonal algae blooms. Phytoplankton are then rapidly consumed by copepods. Copepods are a zooplankton that ferociously graze on phytoplankton. To put it in scale, a copepod can be likened to a T. Rex, and a phytoplankton can be likened to a rodent or small mammal. To me and you however, copepods are tiny and can barely be seen with the naked eye! These copepods are consumed by anchovies, sardines, mackerel, and other animals. These are the fish that then feed the tuna, salmon, and mahi you might find on your dinner plate.

So next time you sit down to a scrumptious plate of seafood, or the next time you take a long deep breath, you can thank the primary producers, namely the phytoplankton!