Original paper
Evolutionary Euryhalinity of Diatoms in Changing Environments
Carpelan, Lars H.
Nova Hedwigia Band 29 Heft 3-4 (1978), p. 489 - 526
46 references
published: Nov 24, 1978
DOI: 10.1127/nova.hedwigia/29/1978/489
ArtNo. ESP050002903005, Price: 29.00 €
Abstract
Four coastal lagoons (mouths of intermittent streams) located in San Diego County, California were sampled every other week during a one-year ecological survey which included taking routine plankton samples and recording salinity, pH, temperature, dissolved oxgygen, ammonia and phosphate. Salinity ranged from 2 to 96 ‰ in poikilohaline waters in which salinity conditions ranged from fairly stable to extremely unstable; the latter condition seemed to be a case of the exceptional conditions to which Dahl (1956) stated that accepted salinity intervals of brackishwater classifications cannot be applied: more than half of 86 identified species of diatoms were holeuryhaline, a class not recognized by current classifications. However, taxonomic records from Europe, where most brackishwater studies have been made, showed differences of opinion among diatomists: the class or salinity interval to which a species was assigned, in systems such as that of Kolbe (1932) or of the Venice Symposium (1959), varied from one investigator to another. These opinions were tabulated, together with the salinity ranges observed for each of the species in the California lagoons. Using new knowledge and theory advanced since the accepted salinity classifications were proposed, it is possible to interpret the assembled data from several points of view. In this paper taxonomic comments are used to illustrate the concept of evolutionary euryhalinity (Hutchinson 1960 and 1967) and expanding it to include species which are tolerant of both fresh and marine waters; the discussion is based on strategies, both mono- and poly-morphic, presented by Levins (1968) for evolution in changing environments (which the lagoons exemplify); and incorporating current ideas of cellular osmoregulation (Florkin and Schoffeniels (1969). The comments include mention of a proposed salinity classification which would apply to all brackishwaters including those with unpredictable changes. The proposed scheme adds a holeuryhalobe category, encompassing the meso- and poly-halobe categories of previous classifications. Another paper (to be published elsewhere) takes an ecological viewpoint to present the proposed classification which is based on the prior schemes of Heiden (1902), and Kolbe (1932), and of Hustedt (1953), incorporating the poikilohaline/homoiohaline continuum concept of Dahl (1956).
Keywords
coastal lagoons • salinity • plankton samples • diatoms • holeuryhaline • San Diego County • California