Marine scientists in Plymouth have led a major study highlighting the effects of climate change on the plankton populations in UK seas. Published as part of a wide-ranging report by the Marine Climate Change Impacts Partnership (MCCIP), it shows there have been extensive changes in plankton ecosystems around the British Isles over the last 60 years.

It says climate variability and ocean warming have had negative impacts on plankton production, biodiversity and species distributions, which have in turn affected fisheries production and other marine life such as seabirds.

The study was written by world-leading researchers from the University of Plymouth, Marine Biological Association (MBA) and Plymouth Marine Laboratory, along with colleagues at Marine Scotland Science and the Centre for Environment Fisheries and Aquaculture Science.

It forms part of the MCCIP Report Card 2020, which summarises 26 individual, peer-reviewed scientific reports to provide detailed evidence of observed and projected climate change impacts and identify emerging issues and knowledge gaps.

Among the key factors highlighted in the plankton report are:

• There has been a shift in the distribution of many plankton and fish species around the planet.
• The North Sea populations of previously dominant and important zooplankton species (the cold water species Calanus finmarchicus, a major food source for fish, shrimp and whales) have declined in biomass by 70% since the 1960s.
• Species with warmer-water affinities (e.g. Calanus helgolandicus) are moving northwards to replace the species, but are not as numerically abundant.
• The decline of the European cod stocks due to overfishing may have been exacerbated by climate warming and climate-induced changes in plankton production.
• Future warming is likely to alter the geographical distribution of primary and secondary open ocean (pelagic) production, affecting ecosystem services such as oxygen production and the removal of carbon dioxide from the atmosphere.

Professor Martin Edwards, a senior scientist at the MBA and Professor of Ocean Ecology at the University of Plymouth, led the report on plankton. He said: “There have been extensive changes in plankton ecosystems around the British Isles over the last 60 years, mainly driven by climate variability and ocean warming. For example, during the last 50 years there has been a northerly movement of some warmer water plankton by 10° latitude in the North-east Atlantic and a similar retreat of colder water plankton. Future warming is likely to alter the geographical distribution of plankton abundance and these changes may place additional stress on already depleted fish stocks, as well as having consequences for mammal and seabird populations.”

Dr Abigail McQuatters-Gollop, Associate Professor of Marine Conservation at the University, is the lead scientist for pelagic habitats policy for the UK and North Atlantic within the Marine Strategy Framework Directive. She added: “Plankton are vital for many aspects of our lives. Their health affects that of the entire marine ecosystem, they create half of the oxygen we breathe and are crucial for the global food web. To ensure they thrive in the future, we need to understand why changes in the marine biodiversity are happening so policy makers can be prepared and manage for them. This study gives us an overview of what is happening in UK seas and is a key step in evaluating the environmental status of the pelagic habitat.”

Dr Angus Atkinson, Senior Plankton Ecologist at Plymouth Marine Laboratory, commented: “This report documents the profound changes in the plankton that have occurred over the last 50 years. While we know that these are related to our warming climate, it is only by building on our UK network of time series data that we can understand the exact mechanisms behind the changes observed. With time series’ spanning multiple decades we can start to differentiate the climate signal from the natural seasonal patterns observed in the plankton. At our Western Channel Observatory's L4 sampling station, we have generated over 30 years of weekly plankton data, which form an important contributor to this important new assessment.”

The MCCIP Report Card 2020 highlights the current and future impacts of climate change on UK seas, dependent industries and society, and features contributions from more than 150 scientists at over 50 leading research organisations across the UK.

It shows that climate impacts for UK coasts and seas are varied and far-reaching, supporting findings reported at a global level by the Intergovernmental Panel on Climate Change (IPCC) in their Ocean and Cryosphere in a Changing Climate report last year.

This information is crucial to not only help develop adaptation measures and management actions to support vulnerable marine life and habitats, but also to help UK industries and wider society prepare for and adapt to these far-reaching marine climate impacts.

Story by the University of Plymouth