These in turn can pollute shellfish and cause shellfish poisoning. Some species produce light and if you ever paddle at night along the waters edge, you may see the sea sparkle as it is disturbed, this is called bioluminescence. Let's start with the phytoplankton, they are the oceanic equivalent of grass. The picture shows a chain of diatom cells, which are very common in the Southern Ocean. Each cell is an individual plant, encased in a glassy shell - if each were the size of a squash ball, a krill would be about the size of a bus.
Phytoplankton have an important role in the marine ecosystem.
These in turn are eaten by grazing animals such as copepods and krill. Each day during summer, phytoplankton accumulate about 1 gram of carbon for each square metre of sea surface. In this survey we are mapping the distribution of phytoplankton in relation to the environment and the dependant zooplankton. We measure the amount of phytoplankton by extracting and quantifying the chlorophyll from water samples. This is done continuously by a special instrument which takes water samples from the sea surface as we move along.