The fascinating world of dinoflagellates

A sure way to bring a conversation to a full stop is to mention an interest in algae, plankton and dinoflagellates. These are miniscule creatures living in all the world’s oceans on which we are dependent. As with terrestrial vegetation, the plankton make oxygen through photosynthesis, and therefore without them there would be no life on earth. One of the smallest creatures on earth and we are dependent on them for our existence!

Most people won’t even notice algae, plankton and dinoflagellates until they suddenly bloom and are visible, for example, in the form of ‘red tides’. As they are so minute the only way to study them is by examining them under a powerful microscope in a laboratory.One of the areas of research of the Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer – French Research Institute for Exploitation of the Sea is to find out  why algae suddenly bloom, and when they  do, why they are sometimes toxic and sometimes harmless. Ifremer also looks at the effects on the surrounding ecosystems and human population. Ifremer’s chief lab technician, Marie-Pierre Crassous, took us through the process of identifying toxic algae.

Why research toxic algae?
Phials of water gathered from various locations are carefully brought to the laboratory and are kept in a controlled environment. Small samples are taken for examination under the electron microscope. Today Marie-Pierre was looking specifically for the dinoflagellate Alexandrium minutum, which is responsible for toxic blooms in Brittany. With a magnification of ‘only’ 200 times, they were clearly visible. In turn, these toxic blooms are linked to Paralytic Shellfish Poisoning which makes the shellfish unfit for human consumption. Her sample contained a number of Alexandrium minutum and, by counting the total in the 50 ml sample, she can calculate how many there are in a given area.

Ifremer’s research also looks into why similar toxic algal blooms occur in different locations, and whether they arise independently or they have in one way or another been transported between locations. For information for a film about the role of ballast water in transporting species we met with Patrick Gentien, an expert on toxic algae and how they spread. Patrick was a fount of information, and talked us through the issues around the transport of species. Not only that, but we also got a glimpse into the complexity of the issue and what factors have to be considered during research.

Our visit to Ifremer was very fruitful, and we are looking forward to collecting samples while at sea on the Morgan so that we can examine them under our own small microscope.

With thanks to Annie Chappelle for briefing us so well and for organising our visit.
With thanks to Marie-Pierre Crassous for taking us through the laboratory process.
With thanks to Patrick Gentien for his time and trouble in helping us see through a mass of information.

Photo:
Alexandrium minutum, © Copyright E. Erard IFREMER