Revision of Kolbe's System der Halobien Based on Diatoms of California lagoons

Abstract

The six categories proposed are: freshwater stenotopic, freshwater eurytopic (oligohaline), marine stenotopic (marine), marine eurytopic (polyhaline), mesohaline and holeuryhaline. The first three, which are more or less specialized, are well-established; but the last three, which consist of more or less generalized species, are either not recognized, or in need of redefinition. Holeuryhaline species, representing retention of evolutionary euryhalinity, can live in the entire range of mixohaline water, from freshwater to hyperhaline, as found in southern California coastal lagoons; the mesohaline category is not very different, but lacks hyperhaline tolerance; the polyhaline, tolerant of all but freshwater, also has lost little of the primitive lability. Stenotopic species are limited to environments with slow, small and predictable changes. The species of other categories require eurytopy for life in waters where changes can be rapid, large and random. The holeuryhaline category is the only addition to the classificatory scheme of Kolbe whose other categories are redefined on the basis of tolerance to many factors rather than on Kolbe's criterion of centers of distribution determined by salinity at maximum abundance.