Periodicity and distribution of brackish Vaucheria species from non-tidal coastal areas in the S.W. Netherlands

Data are given on periodicity and distribution of fourteen Vaucheria species in saline inland areas in the S.W. Netherlands. Periodicity was studied by monthly sampling of permanent sample plots measuring 50 x 50 cm2 during the years 1970-1972. Salinity and soil-moisture content of the upper soil layer were measured near the sample plots. Periodicity and distribution of Vaucheriae were found to be correlated with soil-moisture and salinity conditions. Vaucheria growth as a whole attains optimum development in the colder seasons. Two species occur in all seasons, and two species show optimum summer occurrence. Germination of oospores takes place mainly under low-salinity conditions. The pattern of distribution shows a similar zonation as described earlier for a brackish area in the northern part of the Netherlands.