Salinity and the Ecology of Dunaliella from Great Salt Lake

Abstract

S U M M A R YStudies are reported on the distribution and salinity tolerances of populations of Dunaliella, a eucaryotic alga, in Great Salt Lake, Utah, U.S.A. This lake provides salinities varying from about 10 % (w/v) NaCl to saturated (greater than 30 % w/v). The alga is found throughout this salinity range, although population density varies markedly, mainly because of the influence of grazing animals in waters of low salinity. Enrichment cultures were set up using a range of salinities ; at the lower salinities a wide variety of algae grew, but at the higher ones only Dunaliella was obtained. However, cultures derived from saturated brine and grown at salinities of around 25 % (w/v) were not optimally adapted to these conditions, but grew and photosynthesized better in 10 to 15 % (w/v) NaCl. A natural population from a saturated brine also had an optimum at a lower salinity than its habitat. It is concluded that although this eucaryotic alga is able to grow in saturated brine better than any other alga, it is not optimally adapted to these conditions and is apparently able to maintain populations at high salinity only because it meets no competition from other algae. I N T R O D U C T I O NMembers of the eucaryotic algal genus Dunaliella are widespread in saline environments (Teodoresco, 1905(Teodoresco, , 1906Hof & Fremy, 1933; Lerche, 1937;Volcani, 1944;Smith, 1950; Butcher, I959), and have been much studied, perhaps because of the striking pink to red coloration which they sometimes impart to waters and sediments. The genus Dunaliella was first separated from Chlamydomonas by Teodoresco ( I 905) on morphological grounds, and since then a number of species have been described (Butcher, 1959). These occur in diverse habitats, from almost fresh water to saturated brine, although the salinity requirements of different species have not been specified. Most attention has been paid to cultures able to grow in media of greater salinity than sea water. The mechanism by which Dunaliella withstands high salt concentrations differs from that of the halobacteria (Kushner, I 968 ; Larsen, 1967). In the latter, it appears that the salt concentration (primarily potassium, with some sodium) inside the cell is higher than the external one, permitting water to flow in, and the enzymes of the bacteria are unusually resistant to high concentrations of salt. In Dunaliella, high concentrations of glycerol are synthesized intracellularly through photosynthetic processes (Wegmann, I 971) and the alga maintains an intracellular glycerol concentration such that the intracellular osmotic pressure is higher than the extracellular pressure (Ben-Amotz & Avron, 1g73), thus permitting the alga to take up water even when growing at high salt concentrations. The intracellular salt concentration is lower than the external concentration, and intracellular enzymes of Dunaliellu are actually inhibited by high salt concentrations (Johnson et al. 1968).Despite the evolutionary and ecological interest in this alga, little work has been done in ...

The protozoa of a Western Australian hypersaline lagoon

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“…At NaCl saturation only a few organisms are able to grow successfully (Nixon 1970;Larsen 1980), the two most prominent being D. salina and the halobacteria. While the salt tolerant D. salina is able to grow at salinities from near sea water levels to saturation (Masyuk 1973;Brock 1975) the halobacteria are not able to grow at salinities lower than about 12% NaCl. Even these organisms do not grow best at saturation but have an optimum somewhat below that (Fig.…”

The Great Salt Lake Ecosystem (Utah, USA): long term data and a structural equation approach

“…This is not to say that hypersaline environments have gone unstudied: recent microbial work in hypersaline ponds , Paerl and Yannarell 2010 and concern over the conservation of saline lakes (Williams 1993a(Williams , b, 1998(Williams , 2002 are notable. However, after an extensive bibliographic compilation of saline lake and inland sea literature (.1200 papers dated prior to 1994, Larson and Belovsky 1999), we found few studies available on the Great Salt Lake ecosystem and its biota (e.g., Hayes 1971, Wirick 1972, Porcella and Holman 1972, Stephens 1974, Brock 1975, Stephens 1990, Post 1975, Stephens and Gillespie 1976, Cuellar 1990, Collins 1977, Felix and Rushforth 1977, Rushforth and Felix 1982, Stephens and Birdsey 2002, Wurtsbaugh 1988, Wurtsbaugh and Berry 1990, and these were short term and very limited in scope. In addition, most of the extensive and long term studies of other hypersaline lakes were for much smaller lakes with very different environmental patterns (e.g., Mono Lake, USA, a deep lake basin: Dana et al 1990Dana et al , 1993Dana et al , 1995; Lake Grassmere, NZ, a seaside lagoon lake: Wear and Haslett 1986, 1987).…”

Formation of algae growth constitutive relations for improved algae modeling.

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