Predictors of long-term variability in NE Atlantic plankton communities

Area of Science:

• Marine ecology
• Oceanography
• Environmental science

Background:

• Anthropogenic pressures, including climate change and nutrient pollution, are rapidly altering marine environments.
• Plankton are crucial indicators of ecosystem health due to their rapid response to environmental shifts.
• Lifeform categorization aids in understanding ecological patterns and assessing pelagic habitats.

Purpose of the Study:

• To investigate how plankton lifeform abundance trends correlate with environmental changes.
• To identify the relative influence of various human pressures on plankton communities in the North-East Atlantic.
• To inform sustainable management practices for marine ecosystems.

Main Methods:

• Analysis of 29 years (1993-2021) of Continuous Plankton Recorder data from the North-East Atlantic.
• Utilizing random forest models to predict plankton lifeform abundance variability.
• Examining trends in lifeform abundance against environmental gradients.

Main Results:

• Random forest models explained 57-80% of lifeform abundance variability.
• Inter-lifeform correlations and shared environmental responses were prevalent, suggesting bottom-up control.
• Key environmental predictors included longitude, bathymetry, mixed layer depth, nitrogen-to-phosphorus ratio, and temperature.
• Contrasting responses were observed: small copepods increased with warming, while meroplankton, large copepods, and fish larvae declined or remained stable.

Conclusions:

• Changes in stratification (mixed layer depth) and nutrient ratios significantly impact North-East Atlantic plankton communities.
• Addressing climate change and reducing nutrient pollution are essential for improving pelagic habitats.
• Continued monitoring and research are vital for understanding and managing marine ecosystems under pressure.