Importance of Phytoplankton

Phytoplankton bloom (water that looks turquoise) near the
 coast of Vancouver Island, British Columbia, Canada.
 Image collected by MODIS.
 Picture courtesy of Sound Waves Newsletter.

What are Phytoplankton?

Phytoplankton are tiny microscopic organisms that live near the surface of ocean water. Diatoms, dinoflagellates, green algae and cyanobacteria are amongst some of the most common phytoplankton. Like Plants, phytoplankton also have chlorophyll to use sun energy and turn it into chemical energy via photosynthesis. They use the CO2 from the atmosphere and turn it into oxygen, which then is used by humans and the marine life in the ocean. (1)

Importance of Phytoplankton:

While these organisms may be tiny in size, the impact they have on the surrounding ecosystem is phenomenal. As the main primary producers for marine life and important for the ocean biology and climate change, any changes in their productivity can have negative impacts not only on ocean biodiversity, fisheries, human food supply, but it can also increase the pace what global warming is occurring. (Richardson & Schoeman)

Picture Courtesy of Health Totem

Temperature and Phytoplankton in the Northeastern Pacific Ocean:

Phytoplankton’s growth depends on the available nutrients such as nitrate, phosphate, carbon dioxide and sunlight. (Richardson. Et al) While they are able to get the carbon dioxide and sun light from the atmosphere, in needs the nitrate and phosphate from the either runoffs or from lower layers of the water. Thus mixing of the different water layers is critical for nutrients being brought up from lower layers of the ocean to the surface where phytoplankton lives.

As ocean temperature increase, and water layers becoming more stratified changes in the abundance of different phytoplankton species can also alter- leading to one specie of phytoplankton being more abundant than others. (Richardson. Et al) Alteration of certain phytoplankton species can lead to tropic mismatch among plankton and other marine species. (Edwards &Richardson) Data from Monterey Bay Research Institute showed that with temperature changes (increase) in 2003 saw a decrease in Diatoms and saw an increase in Dinoflagellates. (MBARI) Diatoms blooms are dependent on day length or light compared to Dinoflagellates, whose cues are independent of the temperature or day length. (Richardson &Edwards) As temperatures increase and the ocean becomes more stratified, the diatoms have to move lower in the column in order to reach cooler waters and thus decreasing their nutrient availability compared to the dinoflagellates which can swim all along the column. (Richardson et. Al, Edwards & Richardson)

Data showed as temperature increased, shallow water column became stratified due to reduction in local upwelling winds leading to centric diatoms dying off and dinoflagellates blooming. Research also shows as the temperature increases, changes in blooming time for certain phytoplankton species are also changing. (Edwards & Richardson)  During summer meroplankton had moved forward collectively by 27 days and dinoflagellates by 23 days. (Edwards & Richardson) Diatoms on the other hand showed variety in its phenology, with certain taxas occurring both earlier and later during the spring and autumn blooms. (Edwards & Richardson) Changes in bloom times can lead to potential risk of desynchronizing trophic linkages between primary and secondary consumers and primary producers. (Thackery) Such disruption could have catastrophic environmental consequences and affect delivery of important ecosystem services, especially on food production ( Portner &Farrell)

The last time dinoflagellates were predominate were during the Late Paleocene Thermal Maximum which occurred 55 million year ago was associated with a rapid carbon release into the atmosphere and oceans. (MBARI) Results of this rapid carbon release led to mass extinction of various species. This switch in abundance of different plankton species in 2003 off the coast of California suggests that anthropogenic release of CO2 has crossed a tipping point in climate. (MBARI)

Picture from MBARI.org