ORCID

Abstract

Pseudo-nitzschia and Dinophysis are two commonly occurring phytoplankton genera along Europe’s Atlantic coast. Species within these genera can produce toxins that accumulate in shellfish and pose health risks if consumed. Sustained monitoring of shellfish growing waters has generated decades-long time-series for these two genera, which have been considered for use in statutory biodiversity assessments as proxies for diatoms and dinoflagellates. There is also evidence that distributions are shifting; It is important to document these changes to anticipate risks for shellfisheries, and higher trophic levels. We assessed whether Pseudo‑nitzschia and Dinophysis data could support statutory biodiversity assessments and quantified distributional change through time. We compared seasonal and interannual variability in Pseudo‑nitzschia and Dinophysis with total diatom and dinoflagellate abundance at two UK stations (L4, English Channel; Stonehaven, Scotland) and used Continuous Plankton Recorder data (1960–2020) to map decadal distributions. A notable spring increase in Pseudo‑nitzschia occurred in the southern/eastern North Sea since ∼2000, followed by a post‑2010 reduction. Dinophysis remained largely summer‑restricted and declined after 2000 in parts of the eastern North Sea. Station and CPR data were complementary, but not directly comparable, reflecting differences in spatial variability and capture efficiency. We found limited evidence, however, to support proxy potential for either genus. While there were some localised seasonal correlations, they were generally inconsistent or weak. Our results show that neither genus is suitable as a proxy for diatom or dinoflagellate lifeforms in statutory biodiversity assessment, but both are potentially valuable as evidence for HAB pressure when interpreted alongside toxin measurements.

Publication Date

2026-04-30

Publication Title

Harmful Algae

Volume

156

ISSN

1568-9883

Deposit Date

2026-05-26

Funding

We are grateful for the funding received from the UK Department for Environment, Food & Rural Affairs (Defra) through the marine arm of their Natural Capital and Ecosystem Assessment (NCEA) programme (NC34 Pelagic program-“PelCap”). The marine NCEA programme delivered evidence, tools and guidance to integrate natural capital approaches into decision making for the marine environment. Find out more at https://www.gov.uk/government/publications/natural-capital-and-ecosystem-assessment-programme. AMG would like to thank the United Kingdom National Environmental Research Council (UKRI-NERC) for support through the NERC Knowledge Exchange Fellowship Scheme (NE/R002738/1). MF acknowledges funding from Defra, the University of Plymouth, and The Alan Turing Institute’s Enrichment Scheme. Current funding that supports data collection by the CPR survey in the North Atlantic includes: the UK Natural Environment Research Council; Atlantic Climate and Environment Strategic Science (AtlantiS) NE/Y005589/1, Department for Environment Food and Rural Affairs UK ECM_64770, National Science Foundation USA A101666/83643000, NERACOOS N21A01303, Fisheries and Oceans Canada F521A-210734/001/HAL, Horizon 2020: 862428 Atlantic Mission and AtlantECO 862923, IMR Norway and Ireland Marine Institute SERV-22-FEAS-090. L4 plankton data were provided by the Plymouth Marine Laboratory’s (PML) Western Channel Observatory (https://www.westernchannelobservatory.org.uk), which was funded as part of the UK’s Natural Environmental Research Council’s National Capability Single Centre Science Programme, grant number NE/R015953/1. Marine Directorate Scottish Coastal Observatory data was collected under ADP#703. The Marine Directorate Scottish Coastal Observatory Stonehaven site is funded as part of ADP#703.

Keywords

Climate change, Diatoms, Dinoflagellates, Dinophysis, Harmful algae, Phytoplankton, Plankton monitoring, Pseudo-nitzschia, Time-series

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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