Decadal changes in global phytoplankton compositions influenced by biogeochemical variables

Area of Science:

• Marine ecology
• Oceanography
• Climate science

Background:

• Global environmental changes challenge ocean ecosystem structure and function.
• Understanding phytoplankton dynamics is crucial for ocean ecosystem health.
• Long-term trends in phytoplankton biomass and composition are needed.

Purpose of the Study:

• Investigate decadal trends (2002-2015) of phytoplankton composition and biogeochemical parameters.
• Analyze trends across the Global Ocean (GO), Southern Ocean (SO), and Arctic Ocean (AO).
• Identify factors controlling phytoplankton variability.

Main Methods:

• Utilized ocean color remote sensing data.
• Employed assimilated data from NASA's Ocean biogeochemical model.
• Analyzed phytoplankton composition, Chlorophyll-a concentration (Chl-a), and biogeochemical parameters.

Main Results:

• Diatoms dominate phytoplankton in the SO and AO; coccolithophores dominate the rest of the GO.
• Nitrate is not limiting in the SO and AO, while PAR limits phytoplankton.
• Increased Chl-a and diatoms in SO and AO; decreased in GO due to rising sea surface temperatures.

Conclusions:

• Phytoplankton community shifts occur on regional and global scales.
• These shifts have significant implications for climate change and marine ecosystems.
• Co-limitation by iron and PAR affects phytoplankton growth in the SO.