Le microplancton de la rivière d'Auray

The sample data of the microplankton collected in the Auray River between 1961 and 1963 enabled us to establish the permanent or seasonal character of numerous organisms, many of which are unevenly distributed between downstream and upstream.Tides and currents, temperature and salinity are some of the factors that are responsible for the distribution of micro-organisms. This is the reason why fresh water or brackish water types are mostly found in the upper part of the river-which is subject to rises in water level-whereas oceanic types are more numerous next to the mouth of the river.An extended drop of the temperature favours the development of cold water elective types. The composition of microplankton, its relative abundance and its distribution in the Auray River depend on physico-chemical factors that are conditioned by the climate or the topography....