Plymouth scientists highlight effects of climate change on UK’s plankton

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 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.

Emergence of a cold-water ‘blob’ in the North Atlantic sub-polar gyre region

Martin Edwards, 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.”

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.

Get the report here:

Warming drives ‘fundamental’ changes to ocean.

Climate change has wrought major changes to ocean stability faster than previously thought, according to a recent study, raising alarms over its role as a global thermostat and the marine life it supports.

The research published in the journal Nature looked at 50 years of data and followed the way in which surface water “decouples” from the deeper ocean.

Climate change has disrupted ocean mixing, a process that helps store away most of the world’s excess heat and a significant proportion of CO2.

Water on the surface is warmer — and therefore less dense — than the water below, a contrast that is intensified by climate change.

Global warming is also causing massive amounts of fresh water to flush into the seas from melting ice sheets and glaciers, lowering the salinity of the upper layer and further reducing its density.

This increasing contrast between the density of the ocean layers makes mixing harder, so oxygen, heat and carbon are all less able to penetrate to the deep seas.

Long-term responses of North Atlantic calcifying plankton to climate change

Study on calcifying plankton and climate change published in Nature Climate Change

Abstract:

The global increase in atmospheric carbon dioxide concentration is potentially threatening marine biodiversity in two ways. First, carbon dioxide and other greenhouse gases accumulating in the atmosphere are causing global warming. Second, carbon dioxide is altering sea water chemistry, making the ocean more acidic.

Although temperature has a cardinal influence on all biological processes from the molecular to the ecosystem level, acidification might impair the process of calcification or exacerbate dissolution of calcifying organisms.

Here, we show however that North Atlantic calcifying plankton primarily responded to climate-induced changes in temperatures during the period 1960–2009, overriding the signal from the effects of ocean acidification. We provide evidence that foraminifers, coccolithophores, both pteropod and non-pteropod molluscs and echinoderms exhibited an abrupt shift circa 1996 at a time of a substantial increase in temperature and that some taxa exhibited a poleward movement in agreement with expected biogeographical changes under sea temperature warming. Although acidification may become a serious threat to marine calcifying organisms, our results suggest that over the study period the primary driver of North Atlantic calcifying plankton was oceanic temperature.

more information: https://www.nature.com/articles/nclimate1753