Continuous Plankton Recorder in Irish waters

Ireland has obligations under the EU Marine Strategy Framework Directive to deliver food web indicators under Descriptor 4. Specifically, the following elements must be met for at least 3 trophic guilds:

1. The diversity (species composition and their relative abundance) of the trophic guild is not adversely affected due to anthropogenic pressures.

2. The balance of total abundance between the trophic guilds is not adversely affected due to anthropogenic pressures.

3. The condition of the habitat type, including its biotic and abiotic structure and its functions (e.g. its typical species composition and their relative abundance, absence of particularly sensitive or fragile species or species providing a key function, size structure of species), is not adversely affected due to anthropogenic pressures.

Of the three required trophic guilds, at least one must be a primary producer, and another must be a secondary producer. The Continuous Plankton Recorder provides a survey of two such trophic guilds (phytoplankton and zooplankton). These are the only available time series for these guilds. Time series of these data exist in Irish waters, but were discontinued in 2017. The purpose of this project is to continue Transect Route D south (see map), which begins 450 nautical miles out and usually finish around the southernmost tip of Ireland. Occasionally the north transect route may be used as an alternative due to bad weather.

These data also populate two OSPAR common indicators; FW5/PH1 OSPAR common food webs indicator (Changes in average trophic level of marine predators and PH2 OSPAR common pelagic habitat indicator (Plankton biomass and/or abundance). OSPAR common indicators are designed to align with the MSFD but have the added value of covering Ireland’s food-web contributions to the 2023 OSPAR Quality Status Report (QSR) for the NE Atlantic.

The Continuous Plankton Recorder (CPR) Survey began in the North Sea in 1931, operating out of the University College of Hull. It has continued to collect plankton for almost, 90 years and has steadily grown in scope, collecting plankton from all major ocean basins. Since 1990, the Marine Biological Association in Plymouth has hosted the Survey. The MI had been making a contribution to the cost of the programme undertaken by PML, and using the data to feed into Irelands MSFD report (which requires measurement of the status of ocean food webs in Irish waters). However, due to cutbacks incurred several years ago, PML curtailed transects in the Irish zone and this has given rise to the need to resurrect the time series before too big a hiatus opens up in it. The EMFF CPR project reopened the time series and demonstrated its feasibility as a long-term indicator.

Samples continue to be collected from around the globe; however, core monthly sampling is focused in the North Atlantic and North Pacific. Whilst maintaining consistent methodology throughout, to date, the Survey has sampled over seven million nautical miles of ocean, resulting in over half a million CPR samples with corresponding sample data. 

Being the largest, most geographically extensive marine monitoring program in the world, the CPR Survey not only has a wealth of experience, but has helped to pass this knowledge on to other countries (e.g. Canada, Japan, Australia, New Zealand and Brazil), by establishing several successful sister Surveys under the umbrella of the Global Alliance of CPR Surveys.

The collection of continuous plankton data on a consistent annual basis will also feed into the data needs for informing on how plankton abundance and distribution may be changing under the pressures of global climate and ocean change.