Gradients of salinity stress, environmental stability and water chemistry as a templet for defining habitat types and physiological strategies in inland salt waters

Abstract

The search for pattern in the geographic occurrence of salt lake flora and fauna often reveals strong associations of specific taxa with certain types of water chemistry. Solute composition, along with salinity and habitat stability, may provide a templet shaping the distribution of many organisms inhabiting saline lakes. A review of studies demonstrating habitat associations, specific solute tolerance, and ionic and osmotic adaptations provide evidence of fidelity to particular conditions of environmental chemistry across a wide taxonomic spectrum. Under low salinity conditions, some species show osmoregulatory adaptability to varied solute composition but the capacity for such flexibility is reduced with increased salinity and only certain taxa are found in hypersaline waters dominated by a particular solute. Anionic ratios of chloride, bicarbonate-carbonate, and sulfate appear to be especially important determinants of distribution. Specific solute tolerance presents an alternative explanation to disrupted hydrographic connections in describing how biogeographic distributions may be restricted to certain aquatic habitats in arid regions. Physiological adaptations to chemistry, exemplified in the brine fly genus Ephydra, may be an integral part of the evolution, ecology and diversification of saline water organisms.

Salinity and freshwater discharge determine rotifer distribution at the Mossoró River Estuary (Semiarid Region of Brazil)

“…Due to the well-known negative influence of salinity on many zooplankton species (e.g. Hammer, 1993;Lansac-Tôha and Lima, 1993;Keller and Conlin, 1994;Williams, 1998;Epifanio and Garvine, 2001;Herbst, 2001;Ara, 2002;Derry et al, 2003;Toumi et al, 2005), one would expect to find lower rotifer richness and abundance at zones with higher salinity, but the opposite pattern was observed for the present study, salinity, richness and abundance showing higher values in the UZ. However, seasonally, salinity and rotifer numbers showed major contrasting patterns which were the most critical structuring forces on rotifer distribution in the present study.…”

“…Miracle and Serra, 1989;Hammer, 1993;Lansac-Tôha and Lima, 1993;Keller and Conlin, 1994;Onwudinjo and Egborge, 1994;Williams, 1998;Epifanio and Garvine, 2001;Herbst, 2001;Ara, 2002;Derry et al, 2003;Toumi et al, 2005;Fontaneto et al, 2006;Zakaria et al, 2007). However, despite these previously accomplished studies, new questions frequently arise and contrasting results suggest that the influence of environmental factors on species composition is site-dependent.…”

Zooplankton diversity and its relationship with environmental changes after the filling of a temporary saline lake in the semi-arid region of La Pampa Argentina

“…On the other hand, it is well known that there is an inverse relationship between zooplankton richness and abundance and the concentration of total dissolved solids (Hammer, 1986;Green, 1993;Williams et al, 1998;Hall & Burns, 2003;Ivanova & Kazantseva, 2006), due to the increasing environmental stress produced by the increase in salinity (Herbst, 2001), but in saline lakes, biomass tends to be higher due to the occurrence of large-sized zooplankton species that can thrive since the environmental stress causes lack of fishes (Evans et al, 1996).…”

Biology of Boeckella poopoensis Marsh, 1906 (Copepoda, Calanoida) in natural conditions in temporary saline lakes of the central Argentina

“…Salinity is an abiotic factor that can determine the zooplankton assemblage of South American aquatic ecosystems (Hurlbert et al 1986, Williams et al 1995, De los Ríos & Crespo 2004, Vignatti 2011, Battauz et al 2013, and therefore, one reason why B. poopoensis was recorded as present from October onwards, might be due to the recorded presence of Boeckella gracilis until the previous month, which is a much less salinity-tolerant species but a potential competitor of B. poopoensis. In these environments, which generate high physiological stress to organisms, species such as B. poopoensis might possess an adaptive advantage, since their ability to tolerate increased salinity allows them to find refuge against competition or predation by some fish (Herbst 2001, Santangelo et al 2008, but not by flamingos (Battauz et al 2013). Therefore, B. poopoensis could be considered a typical species for when temporary lakes have become relatively stable and not for the period of succession that occurs when a new hydroperiod begins.…”