Students Research Presentations: Assessing trends in phytoplankton phenology of the global ocean

Year:

2022

Source:

Ocean Sciences Meeting, Virtual

Abstract:

Large-scale climate events- such as climate change or ENSO (El Nino Southern Oscillation)- will have a resulting impact on the phytoplankton phenology of the global ocean. Phytoplankton serves as the primary energy source for virtually all pelagic marine ecosystems. Therefore, changes in phytoplankton bloom events will affect energy transfer to higher trophic levels that could lead to critical changes in marine fisheries. The threshold for a phytoplankton bloom event is region-specific. Regions with an annually high amount of chlorophyll production (e.g. The North Atlantic) will have higher criteria for a bloom event than areas of low annual chlorophyll production (e.g. North Pacific). Using daily OC-CCI chlorophyll-a data from the years 1998-2020 we have defined bloom criteria globally. Within a bloom, there are several key events: Initiation of growing period (bⁱ), Timing of maximum intensity (b^t), Termination of growing period (b^e), and Intensity of the growing period (b^a). Using bloom criteria and the average intensity of the growing period we were able to assess the productivity of a region regardless of phytoplankton population size. Attempting to visualize changes in phenology of phytoplankton productivity we chose to define our methods within the North Atlantic. Our linear regression outputs indicate at 0.05 significance level there is an earlier bloom initiation and longer bloom duration. We calculated an earlier bloom initiation in the North Atlantic of about 6 days per decade. The project’s next steps with be to iterate these methods globally and produce a summarized figure of significant trends for the past two decades.

Mentors:

Greg Silsbe, Ph.D.

Students:

Emilia Lepe, California State University, Monterey Bay