Salinity as a Factor Limiting the Potential Taxonomic Richness of Crustaceans in Ecosystems of Hypersaline Reservoirs around the World (Review)

Abstract

Crustaceans (Crustacea) are one of the most diverse and successful groups in the biosphere, having also mastered different extreme habitats (in addition to freshwater and marine). Based on our own data and >200 literary sources, the way in which the degree of environmental extremeness can limit a potential taxonomic richness of crustaceans has been analyzed using the example of hypersaline waters. It is demonstrated that, with an increase in salinity, the number of classes and orders of the subtype Crustacea decreases linearly; the number of genera and species decreases exponentially. With an increase in environment salinity, the contribution of Arthropoda species to a total species richness of animals in hypersaline waters increases from 49 to 100%, the contribution of Crustacea species to the total species richness of Arthropoda increases from 66 to 78%, and the contribution of Branchiopoda to the species richness of Crustacea increases from 19 to 71%. In hypersaline reservoirs of Crimea in the range from 35 to 120 g/L, salinity is not the main factor determining the species richness and composition of the fauna. A combination of all other factors (first and foremost biotic) plays a more important role, and salinity becomes a tough environmental filter only at higher values (>100–120 g/L).