Hello everyone! This past week was really busy for me so this week’s post is just a short one. Next week I will pick back up with our new species of the month.

What Are They?

The species I wanted to bring attention to this week is the single-celled microalgae called phytoplankton. Similar to land plants, phytoplankton convert sunlight into energy through a process called photosynthesis. This is why phytoplankton are found floating in the upper part of the water column, because sunlight can only penetrate the ocean so deep. 

Phytoplankton require carbon dioxide, sunlight and inorganic nutrients like nitrates and phosphates. These nutrients are converted into proteins, fats and carbohydrates. We observe high amounts of phytoplankton in areas with excess nutrients. This excess nutrients can come from naturally occurring upwelling like La Niña events or runoff of pollutants. When there are too many nutrients available, phytoplankton populations can grow out of control resulting in Harmful Algal Blooms (HABs). HABs have devastating effects on the surrounding species in the area including fish, birds and humans. There are many different kinds of HABs with algae that can produce toxins or use up all the oxygen in the water. 

There are two main classes of phytoplankton: dinoflagellates and diatoms. Diatoms have a rigid, interlocking silica cell wall and depend on ocean currents to move around. Dinoflagellates on the other hand, have a cellulose cell wall and rely on their flagella -a whip-like tail- to move through the water column. 

Why Are They Important?

Phytoplankton are an important part of the marine ecosystem. They are a major food source for many marine species including whales, small fish and invertebrates. They are also responsible for transferring carbon dioxide from the atmosphere into the ocean. During photosynthesis, carbon is stored in phytoplankton where it either returns to the surface to be consumed by a predator or if the phytoplankton dies, it sinks into the deep ocean. According to NASA, phytoplankton transfers 10 gigatonnes of carbon from the atmosphere to the ocean each year. However, continued warming due to carbon emissions will cause oceans to be more stratified over the next century. This means there will be less upwelling and phytoplankton populations are predicted to decline. 

---

References

Bopp, L. (2005). Response of diatoms distribution to global warming and potential implications: A global model study. Geophysical Research Letters,32(L19606).

Gaines, S., & Airame, S. (n.d.). Background: Upwelling. NOAA Ocean Explorer Website: Sanctuary Quest. Retrieved May 20, 2010.

Lindsey, R., & Scott, M. (2010). What are Phytoplankton? Retrieved September 27, 2020, from https://earthobservatory.nasa.gov/features/Phytoplankton