Ireland and UK – June 4th, 2013
Phytoplankton are possibly the most important group of organisms on the planet as they generate most of the oxygen that we breath. Also, as they convert inorganic nutrients and sunlight into vegetative matter, most marine food chains depend on their presence as a primary food source.
Most individual phytoplankton are too small to be seen with the naked eye. When present in high numbers however, their presence may appear as dramatic discoloration of the water, as is the case in this image of a bloom southwest of Ireland. This population growth can be rapid, and typically occur when temperature and nutrient levels rise, usually in late Spring and Autumn. The colour of a bloom can vary from a green to a dark red colour depending on the phytoplankton present.
While blooms can provide more food to organisms higher up the food chain, too much phytoplankton can also do harm. Dissolved oxygen becomes rapidly depleted as the phytoplankton die, sink to the bottom and decompose. This can result in the death of other organisms including shellfish, crabs and fish (click here for more information).