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.

In 2017, coccolithophores at Station L4 were consistently low throughout the year reaching a maximum of only 286 per mL in February and generally remaining below 100 per mL from mid-April – September. However, at Station E1, further out in the English Channel there was a peak in coccolithophore abundance at the beginning of October with maximum abundance at the surface of 800 cells per mL. Unlike coccolithophores, cryptophytes at Station L4 had a good year, with abundance at around 1000 per mL from mid-September to late November. Highest abundance during this period was at 10 m but there was still relatively high abundance through the water column compared with other years. Phaeocystis spp., detected as single cells by flow cytometry, bloomed at the same time as in previous years, with cells first being detected in the upper 10 m at similar concentrations to previous years. However, unlike previous years, there was no accumulation of cells near the seabed which is generally associated with the senescence, sinking and breaking up of colonies.

Concentrations of Coccolithophores Concentrations of Cryptophytes Concentrations of Phaeocystis

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