Diatom species are specific to the salinity that they require. This is the main reason for their division into fresh water and marine species. The characteristic species found in ocean currents at a certain time are mainly due to their different salinity requirements.
Temperature and salinity also affect the extent of an ocean current
and therefore the distribution of diatoms. temperature also influences
the kind and abundance of species, this is also because of the effect of
temperature on the nutrient content of the water. Temperature is also the
main factor which causes the different species of diatoms found at
different latitudes. An ocean current can be characterized by a number
of specific species of diatoms because it contains the specific salinity,
gas content, and temperature necessary for the development of those species.