Change in plankton communities can affect the functioning of marine ecosystems. Plankton play a critical role in global oxygen production (one out of every two breaths we take was produced by phytoplankton!), are integral to nutrient and carbon cycling, and form the base of the entire marine foodweb. Marine ecosystems can be profoundly altered when plankton communities change, whether from direct human pressures or climate alterations (also called ‘prevailing conditions’). We therefore need to understand changes in plankton communities so that the associated human activities, such as nutrient inputs or fishing, for example, can be managed.  

Like all European countries, the UK must ensure that our marine habitats and species are in ‘Good Environmental Status’ under the EU Marine Strategy Framework Directive. As the key component of the pelagic habitat, plankton can provide insight into the state of pelagic ecosystems. We are fortunate that in the UK we have an extensive plankton monitoring programme (Fig. 1) which collects plankton samples throughout our waters, and which can enable to us to assess the status of our pelagic habitats. The UK plankton monitoring programme, however, is made up of a diverse suite of sampling surveys that collect and analyse plankton in different ways. Because of this variability, we developed an indicator that enables us to use all of these datasets together to examine change in UK plankton.

The ‘lifeform indicator’ is based on plankton functional groups, or ‘lifeforms’. Plankton lifeforms are groups of plankton which perform a similar ecosystem role or respond similarly to ecosystem change (Fig 2). When lifeforms are examined in ecologically-relevant pairs, they can provide information about the functioning of the pelagic habitat. The advantage of using plankton lifeforms for the indicator rather than individual plankton species, is that plankton lifeforms are grouped based on biological traits (diet, habitat, etc), so species-level data is not required. This means that data from plankton monitoring surveys that analyse some taxa to the family- or group-level rather than the species-level can still be used to populate the indicator. From a policy perspective, it’s important to use as much data as possible so that the evidence base used to make decisions about managing human activities is as strong as it can be.

This work is the first time that the pelagic plankton community has been assessed on a UK-wide scale using a common indicator throughout UK waters. Our results suggest the UK’s plankton community is changing, but changes are not uniform throughout UK waters, with different regions and lifeform pairs changing to different extents (Fig. 2). Further work is needed to interpret the observed changes and link them to possible management measures. Some of this work will take place under our new ICEGRAPH project.

 The lifeform indicator is also an OSPAR common indicator (PH1/FW5: Changes in Phytoplankton and Zooplankton Communities) which was used for the regional OSAPR 2017 Intermediate Assessment. Here we included further UK datasets in the analysis to develop a more complete picture of the status of UK pelagic habitats. As we refine and interpret the lifeforms indicator, adding additional datasets and expanding the number of years examined, our understanding of change in UK plankton communities will increase, allowing us to better understand links between plankton and other parts of the foodweb and enabling policy makers to better manage human pressures on the pelagic habitat.

Abigail, Plankton and Policy

Read more:

McQuatters-Gollop, A., Atkinson, A., Aubert, A., Bedford, J., Best, M., Bresnan, E., Cook, K., Devlin, M., Gowen, R., Johns, D.G., Machairopoulou, M., Mellor, A., Ostle, C., Scherer, C. and Tett, P., (2019). Plankton lifeforms as a biodiversity indicator for regional-scale assessment of pelagic habitats for policy. Ecological Indicators, 101: 913-925.