Western Channel Observatory

NERC National Capability of the Plymouth Marine Laboratory and Marine Biological Association


L4 flow cytometry data

These plots show data generated using flow cytometry since April 2007. The data can be downloaded from the Pangaea website as files for each year from 2007 – 2011 and from the BODC website from 2012. Once you are ininto either site, type Tarran L4 into the search box to find out how to access the data. Flow cytometry involves using a laser-based machine, to count particles and measure light that they scatter as well as fluoresce. A copy of the protocols can be downloaded here. Different groups of particles have different light scattering and fluorescence properties. This makes it possible for us to distinguish different groups of algae (phytoplankton) in live samples of seawater from L4 because the chlorophyll inside them fluoresces red when the laser beam shines on them. We can also count different groups of bacteria and tiny single celled zooplankton (heterotrophic nanoflagellates) by staining the same seawater samples with a dye that attaches to the DNA in the cells and fluoresces green when the laser beam shines on them. These measurements are taken every week by collecting seawater samples from 4 depths at station L4, bringing them back to the laboratory and then analysing them on the flow cytometer. We then have measurements of the plankton abundance as cells per millilitre of seawater through the water column which we use to see how their abundance changes with time as shown in the example plots below. In all plots the green and orange/red colours show where the abundance is highest.

Whilst 2018 was a year of extremes in terms of some of the groups of plankton analysed by flow cytometry, 2019 was a very quiet year, with all groups attaining at or below average abundances. For example, coccolithophores, which reached a time series high in 2018 (3500-4500 cells per mL), only managed a maximum of 221 cells per mL in June 2019. Nanoeukaryote algae had a single, narrow period of higher abundance (up to 6000 cells per mL), limited to July. During the rest of the year abundance remained at a few 100 cells per mL. Another group with a single period of higher abundance was the picoeukaryote algae, in June-July. This contrasts with previous years in which there have been 2 peaks in abundance in spring and summer.

Concentrations of Coccolithophores Concentrations of Nano Eukaryotes Concentrations of Pico Eukaryotes

About Us

The WCO is a partnership between the Plymouth Marine Laboratory and the Marine Biological Association.

How are we funded?

The core work of the WCO is funded as part of the UK Natural Environment Research Council's National Capability.

Contact Information

For more details about the WCO please contact:

Dr Tim Smyth
Western Channel Observatory
Plymouth Marine Laboratory
Prospect Place
email: tjsm@pml.ac.uk