Hunger to the Ocean: The Decline of Phytoplankton

By Laura Acevedo, Juan David Gaitán, María Paula Gómez, Jorge Gutiérrez, Luis Daniel Rojas, Laila Saud, Mariana Uscategui

Editor’s note: This poster is one of three selected from projects done by senior students at St. George’s School in Bogotá, Colombia.

The decline of phytoplankton relates to a most important consequence to the North Pacific ecosystem: A significant reduction of phytoplankton implies the decline of all other species in the ecosystem and their possible extinction, caused by changes in the carbon cycle and food web.

Phytoplankton is one of the most important organisms for sustaining oceanic life due to its role in the oceanic food chain as a primary producer and cornerstone in the nutrient and carbon cycle. However, according to a recently published NASA study, diatoms, the most common type of phytoplankton, have decreased during the last 15 years with significant losses taking place in the northern hemisphere, especially in the North Pacific region where the concentration of diatoms has declined nearly 1 percent per year since 1998. This decline is mainly attributed to a decrease in the availability of nutrients due to a shallowing of the mixed layer which has been apparently affected by an increase in photosynthetically available radiation (PAR). From this the following question arose: How has climate change affected the phytoplankton concentration in the North Pacific during the last 15 years, and has the decrease of phytoplankton posed a risk to the ecosystem in that area?

In order to approach these questions the following objectives were stated: Describe the research and findings of the NASA study, use the information provided by the SeaWifs and the MODIS/Terra satellites to corroborate the magnitude of the diatom decline based on oceanic chlorophyll concentration, describe the importance of diatoms for the North Pacific ecosystem in both biotic and abiotic aspects, remark on some of the consequences that will arise if this decline continues, and describe how climate change is a directly related to such trends. The research, conducted by Cecile S. Rousseaux and Watson W. Gregg under NASA’s initiative, was extensively consulted for this project. In addition, some data regarding basic oceanic conditions and ecosystem structure are presented as well.

EZ1 Poster (11A - 1) v2-AD
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