Recent research has shown that diatoms exhibit great genetic differences and that they occur in discrete populations, which means that they multiply sexually to a greater extent than previously believed. What makes diatoms special is that if the environment they live in becomes too inhospitable they form resting spores, which gather in sediment at the bottom of the sea. When conditions improve, the spores can be revived.
The study concerned is based on a sample of sediment from a highly eutrophic Danish fjord on the east coast of Jutland, Mariager Fjord, whose anoxic bottoms and bottom sediments today do not show any signs of life. After dating the different layers of a sediment core, the researchers took small pieces of sediment from various depths and transferred them to an environment favourable to diatoms. This enabled them to revive resting spores.
”We revived hundreds of genetic individuals of diatoms and induced them to start dividing again and to form cloned cultures. The oldest are more than 100 years old, the youngest quite fresh. We then identified the revived individuals genetically," says Anna Godhe of the Department of Marine Ecology at the University of Gothenburg.
”We found certain differences between the algae that went into a state of rest at the start of the 20th century compared with those that formed resting spores when the eutrophication was at its worst and the freshest ones of all, but the individuals are for the most part very homogeneous throughout the sediment core, that’s to say 40 000 generations of diatoms.”No traces of genetic impact over 100 years
The article Hundred years of genetic structure in a sediment revived diatom population has been published in the scientific journal Proceedings of the National Academy of Sciences of the United States of America (PNAS). The study has been conducted by Karolina Härnström and Anna Godhe at the University of Gothenburg in cooperation with Marianne Ellegaard and Thorbjørn J. Andersen at Copenhagen University.Contact:
Helena Aaberg | idw
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