PH1: Changes in Phytoplankton and Zooplankton Communities

Phytoplankton and zooplankton form the base of marine pelagic food webs and directly or indirectly support fish, shellfish, and seabirds. Because of their short life cycles and sensitivity to nutrients, temperature, salinity, and hydrographic conditions, they respond rapidly to environmental change. These environmental drivers reflect both natural climatic variability and anthropogenic pressures such as nutrient enrichment.

Plankton composition and abundance fluctuate in space and time due to physical, chemical, and climatic conditions. Human-induced pressures like climate change, pollution, eutrophication, and selective fishing can further alter plankton communities. Different species respond uniquely to environmental changes, so these pressures can shift community composition and structural attributes like diversity, dominance, and size distribution.

Understanding plankton dynamics is essential for ecosystem-based management and assessing ecosystem health. Community variance over time and space indicates ecological state, with stable sites showing low variance and disturbed or recovering sites showing high variance. Tracking changes in variance helps identify shifts toward species-poor states or ecological improvement in pelagic communities.

OSPAR Commission. (2023). Changes in plankton diversity. OSPAR Quality Status Report 2023. Retrieved from https://oap.ospar.org/en/ospar-assessments/quality-status-reports/qsr-2023/indicator-assessments/changes-plankton-diversity/

Contact

Credits

Project partners:

• Rune Lagaisse (VLIZ)
• Willem Boone (VLIZ)
• Felipe Artigas (CNRS ULCO)
• Ankita Vaswani (Hereon)

The PH1 calculations are based on the work of Matthew Holland.
Holland, M. M., & McQuatters-Gollop, A. (2022). PH1_PLET_tool (Version 2.0) [Computer software]. https://github.com/hollam2/PH1_PLET_tool