Surveying 4 million miles of ocean!

The Continuous Plankton Recorder (CPR) survey was set up by Sir Alister Hardy in 1931 and has since evolved into a unique marine monitoring programme that provides the scientific community with its only measure of the state of oceanic plankton for the North Sea and North Atlantic.

CPRs towed behind volunteer ships have collected over 200,000 plankton samples from the North Atlantic

The self-contained automatic plankton recorders continuously collect plankton from a standard depth of 7 m and are towed at monthly intervals by ships-of-opportunity along a number of routes.

Using this simple but highly cost-effective technique, CPRs have been towed by volunteer ships for over four million nautical miles, resulting in the collection of nearly 200 000 plankton samples from all over the North Atlantic. On certain standard routes there now exists a virtually unbroken monthly coverage going back to 1948. The CPR survey is run by the Sir Alister Hardy Foundation for Ocean Science (SAHFOS). this will provide more opportunities to catch fish.

'The experiment I want to make from this college consists of running a number of these instruments on definite steamship routes across the North Sea…." Sir Alister Hardy talking at University College, Hull, in 1929, prior to setting up the survey in 1931.

A unique record
Perhaps the real legacy of Sir Alister Hardy's initial foresight in setting up the survey, is the collection of a unique, biologically diverse dataset (of approximately 400 taxa) that is capable of monitoring and detecting environmental change in a world which has become increasingly affected by man's impact. The long-term time-series of CPR data acts as a baseline against which to measure and distinguish between natural and human related changes.

Using CPR data
Research using CPR data has focused on establishing the existence of large-scale variability across the North Atlantic, which also extends to fish and other marine life.

As the CPR record has lengthened, our understanding of natural variability within the marine environment has also increased. Evidence from CPR records suggests that the plankton integrates hydro-climatic signals and responds sensitively to climate change.

In line with current environmental concerns, the CPR data have been increasingly called upon to address such issues as eutrophication and global warming. Other recent applications of CPR data have included providing information on harmful algal blooms, monitoring and documenting the spread of non-indigenous plankton species, and providing information on changes in marine biodiversity.

This shows how the CPR survey has adapted to a changing world and continues to provide a valuable contribution to management and science, after seven decades of operation. Without such programmes, there would be no information about changes in ecological health over large areas of the ocean and hence no means of assessing measures designed to protect the marine ecosystem from human impacts.

Free access to data
In 1999, SAHFOS adopted a new open-access data policy, which allows free use of CPR data by the international scientific community. The aim of the new policy is to encourage the widest possible use of CPR data and products, by scientists and environmental managers.

CPR survey becomes global
The scale of change observed in the North Atlantic over the last few decades emphasises the importance of maintaining existing programmes and establishing new, long-term and wide-scale monitoring of the world's oceans. With this view in mind, the CPR survey has been incorporated into the initial Observing System of GOOS and has recently been deployed in the Mediterranean, Indian Ocean, Baltic, the Gulf of Guinea, the Southern Ocean and, since 2000, in the North Pacific.

Author

Martin Edwards
Sir Alister Hardy Foundation for Ocean Science
The Laboratory
Citadel Hill
The Hoe
Plymouth PL1 2PB, UK

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