Macroscale patterns of oceanic zooplankton composition and size structure.

Area of Science:

• Marine ecology
• Oceanography
• Plankton dynamics

Background:

• Ocean plankton are crucial for ecosystem function and marine services like fisheries and carbon sequestration.
• Plankton community composition and traits, such as body size, influence these vital services.
• Previous research focused on smaller plankton, with less understanding of larger zooplankton community-level traits and their environmental drivers.

Purpose of the Study:

• To investigate how zooplankton community composition and size structure vary with latitude, temperature, and productivity in the global surface ocean.
• To understand the controls on community-level traits in marine ectotherms.
• To predict the impact of changing ocean conditions on marine services.

Main Methods:

• Utilized the Tara Oceans dataset, a comprehensive global survey of marine plankton.
• Analyzed zooplankton community composition and median body size.
• Correlated these parameters with environmental covariates including latitude, temperature, and productivity indicators.

Main Results:

• Zooplankton abundance and median size decreased in warmer and less productive ocean regions.
• Observed shifts in copepod composition were identified as a primary driver for these changes.
• Some zooplankton clades exhibited inverse relationships, potentially due to diverse feeding strategies.

Conclusions:

• Zooplankton communities are predicted to become smaller in future, warmer, and more stratified oceans.
• The shift towards smaller zooplankton may reduce their effectiveness in the biological carbon pump.
• Understanding these community-level changes is essential for predicting the future of marine ecosystem services.