The Great Salt Lake is actually two lakes. A highly saline (330-gml(-1)) northern arm and a moderately saline (120-gml(-1)) southern arm separated by a semipermeable rock causeway. The lake, particularly the northern arm, has a massive accumulation of organic matter resulting from more than 100,000 years of productivity, cycling from a freshwater to a saline lake, plus the influence of human industry and agriculture in more recent times. The north arm planktonic and attached community consists principally of, in order of biomass: bacteria of at least two genera,Halobacterium andHalococcus; two algae,Dunaliella salina andD. viridis; the brine shrimp,Anemia salina; and, two species of brine fly,Ephydra gracilis andE. hians and possibly one more species. The algae and the bacteria appear to depend on each other for nutrients. The bacteria use organic matter produced by the algae and the algae use ammonia produced by the bacteria and possibly the brine shrimp. The production of ammonia appears to be the rate-limiting step although there is no shortage of other forms of nitrogen in the north arm. Based on aquarium studies, the potential for biomass production of algae and bacteria is much higher than actually observed in the north arm, leading to the postulation of two additional factors controlling population; the grazing of the algae by invertebrates with the excretion of compounds rich in nitrogen, and the effect of a low habitat temperature and winter cold on the bacteria, reducing their metabolic activities to nearly zero. Some aspects of the various organisms and their metabolism are discussed. A comparison is made with recent work on the Dead Sea.

Hutt Lagoon, 28" 1 I'S, 1 14" 15'E, 600 km north of Perth, Western Australia and lying 5 m below sea level is the site of a pilot plant erected by Roche Algal Biotechnology for growing and harvesting the alga Dunaliella salina. The lagoon is filled to a depth of 50-75 cm by rainfall (18% w/v salinity or above) during the winter months and is desiccated to a 5 cm or more thick crust during the summer. Salt from the crust used to prepare a growth medium for D. salina introduced a number of protozoa to the cultures, some of which made great inroads on the algal population. Most of the protozoa in the crust are presumed to be in the form of cysts and originate from more or less permanent seeps and pools (>5% w/v salinity) resulting from the inflow of water from the Indian Ocean on the west and from continental ground water on the east. The salt of the crust is thus a mixture of athalassic and thalassic origin. Only the lower reaches of the seeps are inundated by the winter water rise.Fourteen ciliates, 10 zooflagellates and 4 sarcodines were observed frequently enough in brines of over 15% (w/v) salinity to identify. At least one parasite of D. salina is included in the flagellate group. Although no concerted effort with the phytoflagellates was made, the rarely seen species D. peircei, D. jacobae and Ochromonas cosmopolitus were noted, as well as a Gymnodinium sp. The ciliates include the bacteriophagous Trachelocerca conifer, Metacystis truncata, Chilophrya utahensis, Rhopalophrya salina, Uronema marinum, Condylostoma sp. and Palmarella salina. Those eating both bacteria and algae were Nassula sp., Fabrea salina, Blepharisma halophila, Cladotricha sigmoidea, and Euplotes sp. Ciliates feeding on other ciliates include Podophrya sp. and Trematosoma bocqueti. Among the zooflagellates were several species of Monosiga, Rhynchomonas nasuta, Phyllomitus sp., Tetramitus salinus, T. cosmopolitus, Bodo caudatus, B. edax and 3 other distinctive Bodo species, one being parasitic on D. salina. All of the sarcodina fed on both algae and bacteria, except for the smallest amoeba (4 pm diameter rounded) which did not feed on algae, and included Heteramoeba sp. with both flagellate and amoeboid phases, an orange amoeba, an orange filopodforming organism and a colorless filopod-forming organism, the last three of unknown genus.The relationship of these protozoa to the lagoon and to D. salina culturing is discussed.

No abstract

No abstract

Individuals of Artemia salina, the brine shrimp, were captured from the Great Salt Lake, a highly saline (330--340 g (see formula: solids content) terminal lake in Utah. Electron microscopy revealed the presence of intracellular procaryotic symbionts in the epithelial lining of the midgut. Fine structure and possible role of the symbiont are discussed.

No abstract

Sodium hexametaphosphate (HEX), the solvent of calcium alginate wool used in swabbing inanimate surfaces was studied relative to its effect on various bacterial populations, both pure cultures and wild. It was found that bacteria in wild populations were greatly inhibited, and that a percentage reduction of count was directly related to concentration of HEX. Most gram-positive bacteria were prevented from growing on a medium containing 0.1% HEX. This, or a higher concentration, occurred in the final medium when the method recommended in Standard Methods for the Examination of Dairy Products was followed. Growth of Sarcina lutea occurred on media with higher concentrations than that of inhibition (0.05%), if MgSO 4 ·7H 2 O was incorporated in the medium. Gram-negative bacteria were capable of growing in higher concentrations, even up to 10% HEX. A large percentage of the cells of some strains (represented by Pseudomonas fluorescens ) were lysed on contact with HEX. Lysis could be prevented by the addition of NaCl or MgSO 4 ·7H 2 O. The evidence presented suggests that HEX, a phosphate-glass water-softening sequestrant, interferes with divalent cation metabolism, notably magnesium ion, and possibly others, producing cell division inhibition and loss of cell-wall integrity. The mechanism of action was not elucidated.

No abstract