Pelagic Habitats Assessments

Phytoplankton 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.

PH3: Changes in Phytoplankton and Zooplankton Communities

Pelagic Habitat Indicator 2 (PH2) evaluates changes in phytoplankton biomass and zooplankton abundance, using copepods as a representative zooplankton group. It identifies statistically significant increases, decreases, or no change by comparing a pre-2015 baseline period with 2015-2019 data. The assessment is conducted at a regional scale across OSPAR Regions II, III, and IV using COMP4 units. PH2 detects anomalies relative to natural variability and helps interpret potential impacts on ecosystem structure and functioning.

PH3: Changes in Phytoplankton and Zooplankton Communities (PH2)

Pelagic Habitat Indicator 3 (PH3) focuses on changes in plankton lifeforms to assess community-level responses to environmental pressures. It examines both short-term fluctuations and long-term trends that may signal ecosystem shifts. At the North-East Atlantic scale, plankton changes are closely linked to water column characteristics such as depth, stratification, and freshwater influence. Together, PH2 and PH3 provide complementary insights into spatial and temporal patterns of environmental change in pelagic habitats.

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/