Collecting Plankton

Carboys and Emma

A few weeks ago I went to collect some lovely plankton off the coast of Great Yarmouth. The company were I used to work before (Gardline Environmental), is kindly helping me in my quest for it.

Emma and I went out on one of their fast cats. It was a very clear day and thankfully very calm! I do suffer of seasickness and unfortunately, I am one of the very unlucky ones that really cannot get over it; doesn't matter what I do. But I love the sea so much and I will keep going back.

Emma's version of the event is here:  http://sowhataboutseaweed.wordpress.com/2011/04/11/monday-media-copepod-hunting/

WP2 Bongo net 0.2mm mesh.
AMT20 zooplankton pre-dawn cast

We deployed our nets not too far from the coast in the cold water (8 degrees!) and collected some little zooplankton and copepods for me.

There are different ways of collecting plankton, mainly because it depends on what plankton you want to sample. As I mentioned in my previous post "introduction to plankton", the is quite a variety  of plankton and plankton sizes which can effect the selection of the sampling method. Plants and animals are collected usind different equipment and separately.

I am interested in MESO - zooplankton. This means I want to target animals and in the size range of 0.2-20 mm.

Plankton net cleaning

I also have to consider the environmental conditions of where I want to sample. In the North Sea for example, the water is quite shallow and murky and a little bit colder than in the English Channel. The zooplankton population here tends to be a little bit smaller. For instance, very abundant around here is a copepod species called Temora Longicornis, adult females are about 1mm in length.

The standard way of sampling mesozooplankton is to deploy a 0.2mm mesh sized WP2 plankton net. "WP2" stands for the type of net, it defines the net diameter (usually 57cm) and the proportions of the net. Combining 2 nets together like in the pic to your left makes a "bongo" net.

However I selected a smaller net with a 0.12mm mesh. The picture above shows the little net I used and the  "anatomy" of a plankton net .

We towed the net slowly for a few minutes and then we recovered the sample.  Copepods are delicate and sensitive to light, I need them to stay alive for my experiments so I took a few measures to limit the stress as much as possible. I delicately emptied the cod end into a darkened carboy and made sure the copepods had plenty of water to swim about. Soon I will show you a few pictures of my little ones.

Back at the lab I started sorting them out under the microscope and I set up a culture. They are now reproducing and swimming in my buckets.