The Continuous Plankton Recorder device is towed in surface waters and occupies a similar space to a marine mammal. It has been used to monitor the oceans since 1931. Credit: Marine Biological Association.

Leading experts from the UK and Europe have said the pairing of old and new technologies could unlock advances in plankton science.

Advances in technology – such as microscopic imaging and molecular techniques – have the potential to transform our understanding of global ocean health, according to the authors of a new study.

However, they should not be employed at the expense of long-term plankton monitoring programmes, which continue to provide an essential role in tracking how our seas are shifting in the face of a changing global climate and are essential for informing routine assessments of marine biodiversity required by international law

The scientists, working at universities and government organisations in the UK, France, Sweden and the Netherlands, say novel techniques do offer means of collecting and analysing select types of plankton data more efficiently than traditional methods.

They also have the potential to fill knowledge gaps and generate more complete pictures of plankton dynamics, factors which have led to them being proposed as possible alternatives to current monitoring programmes.

Complement

However, the authors say that the old and new methods come with different advantages and costs, while their uses and benefits – across marine management and scientific communities – can actually complement each other.

As such, they believe more effective ways should be found for old and new programmes to integrate with each other, combined with greater efforts to retain the specialist taxonomic skills needed to accurately assess plankton species and diversity.

Four examples of instruments currently used for automated imaging methods in plankton monitoring: A) The Plankton Imager (Pi-10; Plankton Analytics), consists of a high-speed camera that images all passing particles in a flow of pumped seawater. Images are identified in real-time and uploaded via satellite. B) The ZooSCAN (Hydroptic) uses a flatbed scanner with specialised lighting and a watertight scanning chamber to record high-resolution images of zooplankton samples. C) The Imaging FlowCytobot (McLane Labs) is an automated submersible imaging flow cytometer that captures high-resolution images of particles (triggered by fluorescence) in situ. D) FlowCam is a flow imaging microscope that captures high-resolution images of microscopic particles as they pass through a flow chamber. Credit: University of Plymouth.

Long-term

Many of them are directly involved in long-term monitoring programmes that have been running for more than six decades, and the development of new monitoring technologies, as well as advising on the management of our ocean and seas.

Study lead author Dr Matthew Holland, Research Fellow at the University of Plymouth, said: “Plankton support the entire marine food web and generate much of the oxygen we breathe.

“As such, we need to generate any information possible to ensure we know of changes in plankton communities and the impacts they could have on commercial fish stocks, sea birds, and the general health of the planet.

“There are amazing technologies coming on stream that can help with that – but existing monitoring has provided us with hugely valuable insights over the past six decades, and remains essential in tracking long-term changes in ocean health.”

Growing appreciation

The new study has been published at a time when there is growing global appreciation of plankton.

In September 2024, the Ocean Stewardship Coalition – an initiative of the UN Global Compact – launched a global Plankton Manifesto, which sought to emphasise the critical role of plankton in addressing the interlinked global crises of climate change, pollution, and biodiversity loss.

Senior author Dr Abigail McQuatters-Gollop, associate professor of marine conservation at the University of Plymouth and one of 30 international scientists to work on the Plankton Manifesto, added: “Plankton data are integral for understanding changes in our ocean.

“The new technologies being developed for monitoring plankton are exciting, but it is critical they are integrated with standard methods, many of which use a simple net and have been in place for over a century.

“They rely on people with years of experience in plankton science and research, and it is only through combining this human component with the monitoring methods that we can fully understand the implications of plankton change for marine ecosystems.”

Continued excellence

As part of the study, the authors make a series of recommendations which they believe will enable the scientific community to embrace novel technology, while also ensuring the continuity of standard monitoring time-series. They include:

• Gradual integration and intercalibration: We need to conduct parallel studies which apply novel methods alongside standard plankton monitoring to calibrate, align and verify novel data types against standard microscopy methods to ensure compatibility, consistency, and reliability;
• Rethink how we value and employ taxonomists: The need for skilled taxonomists is increasing, rather than declining, since their skills underpin an expanding suite of sampling methods. We need a much wider realisation of this taxonomic need, at all levels spanning from funder to that of individual institutes;
• Incentivise open data practices: Make data from both standard and novel methods more readily available for public use;
• Improve communication: The message that long-term time series are valuable for climate change research is still not fully recognised, and we need to better communicate the value of long-term science to policymakers, funders and the public, as well as establishing a better understanding of the true costs and benefits involved with the various standard and novel methods; and
• Streamline/reprioritise standardised methods: We need to establish standardised data collection and analysis protocols that integrate standard and novel methods to ensure time-series remain comparable across sites and over time.

The study is published in Ocean & Coastal Management.