Genetic identification and classification of single cell parasites in marine zooplankton

Genetic identification and classification of single cell parasites in marine zooplankton

Associate professor Alf Skovgaard, Ph.D., Department of Algae Phycology, Institute of Biology, University of Copenhagen 

Although the oceans are today well explored, there remain organisms in the sea plankton of which we know very little. One of the groups of such organisms, which have for years evaded the attention of scientists, is the single-cell parasites in marine zooplankton. The microscopic zooplankton, which especially encompass fish larvae and their most important diet, copepods, or a type of water fleas, are a fundamental staple of the marine food chain and have for any years been known to be the hosts of the parasites. Nonetheless, we know very little of the extent of parasitism in zooplankton; indeed, we do not even know to which groups of organisms these parasites belong. Certain recent scientific research has shown that almost half of the eggs and new-hatched fish larvae of such important species as sardine, mackerel, cod and turbot are infected with microscopic single-cell parasites that cause the death of the new-hatched fish larvae. Also the most prolific group of marine animals, the copepods, or water fleas, are infected by parasites that presumably belong to highly diverse groups of organisms. The purpose of this project is to classify the above-mentioned parasites by analysing their DNA. Such a classification is important in future for being able to understand the extension and the effect of parasitism in the marine zooplankton. Parasitism is without doubt able to explain a great deal of the natural mortality of water fleascopepods and fish larvae and thus has significance for the size and health of the fish stocks. With our current shortage of fundamental knowledge of these organisms’ biology, it is not possible to assess the extent of parasitism in zooplankton, let alone assessing the factors that regulate the parasites of zooplankton.