Ospar Commission
OSPAR's Quality Status Report 2023 Friday Ocean Findings Issue 36
Plankton (microscopic algae and animals) form the base of marine food webs, making them important indicators of ecosystem state. Short generational times, small size and, for phytoplankton, direct dependence on dissolved nutrients, make plankton well-suited for detecting environmental change. Changes in plankton communities can affect higher food web levels, such as shellfish, fish, and seabirds, which are supported either directly or indirectly by plankton.

Our 3 plankton Indicator assessments featured in this week's Friday Ocean Findings contribute to our 2023 Quality Status Report which, when viewed together, build a picture of the overall condition of the marine environment of the North-East Atlantic and progress towards achieving our vision of a clean, healthy and biologically diverse North-East Atlantic Ocean, which is productive, used sustainably and resilient to climate change and ocean acidification. The results will also be used by OSPAR Contracting Parties to inform policy decisions.

We hope you enjoy these Indicator Assessments. Please contact us with any comments at [email protected]
Changes in Phytoplankton and Zooplankton Communities

Between 2015 and 2019 plankton functional groups experienced significant changes in abundance, reflecting a continuation of long-term trends. Larvae of benthic invertebrates increased, while other groups mostly decreased. Observed changes were primarily linked to rising temperatures within offshore areas in the North-East Atlantic, and to nutrients in some coastal areas.

Changes in Phytoplankton Biomass and Zooplankton Abundance

Phytoplankton biomass and zooplankton abundance changed significantly (2015-2019), most likely driven by climate change and nutrients. Both components decreased in oceanic habitats (Bay of Biscay), and variable salinity and shelf habitats (Greater North Sea, Celtic Seas). Plankton experienced contrasting trends in all coastal habitats and shelf habitats of the Bay of Biscay and Iberian Coast.

Changes in Plankton Diversity

No significant trends in plankton diversity were detected during 2015-2019 in the Celtic Seas (common indicator assessment), Greater North Sea (pilot assessment), and Bay of Biscay and Iberian Coast (pilot assessment). However, significant but transient changes occurred in one Celtic Seas (2015) and some Greater North Sea (2016, 2019) assessment units.

Further information

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OSPAR Commission
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