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Saline Systems

, 1:11

First Online: 15 December 2005Received: 04 August 2005Accepted: 15 December 2005


This is the first in a series of experiments designed to characterize the Salt Plains National Wildlife Refuge SPNWR ecosystem in northwestern Oklahoma and to catalogue its microbial inhabitants. The SPNWR is the remnant of an ancient ocean, encompassing ~65 km of variably hypersaline flat land, fed by tributaries of the Arkansas River. Relative algal biomass i.e., chlorophyll concentrations attributed to Chlorophyll-a-containing oxygenic phototrophs and physical and chemical parameters were monitored at three permanent stations for a one-year period July 2000 to July 2001 using a nested block design. Salient features of the flats include annual air temperatures that ranged from -10 to 40°C, and similar to other arid-semi-arid environments, 15–20-degree daily swings were common. Shade is absent from the flats system; intense irradiance and high temperatures air and sediment surface resulted in low water availability across the SPNWR, with levels of only ca. 15 % at the sediment surface. Moreover, moderate daily winds were constant ca. 8–12 km h, sometimes achieving maximum speeds of up to 137 km h. Typical of freshwater systems, orthophosphate PO4 concentrations were low, ranging from 0.04 to <1 μM; dissolved inorganic nitrogen levels were high, but spatially variable, ranging from ca. 250–600 μM NO3 + NO2 and 4–166 μM NH4. Phototroph abundance was likely tied to nutrient availability, with high-nutrient sites exhibiting high Chl-a levels ca. 1.46 mg m. Despite these harsh conditions, the phototrophic microbial community was unexpectedly diverse. Preliminary attempts to isolate and identify oxygenic phototrophs from SPNWR water and soil samples yielded 47 species from 20 taxa and 3 divisions. Our data indicate that highly variable, extreme environments might support phototrophic microbial communities characterized by higher species diversity than previously assumed.

Electronic supplementary materialThe online version of this article doi:10.1186-1746-1448-1-11 contains supplementary material, which is available to authorized users.

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Autor: Kelly M Major - Andrea E Kirkwood - Clinton S Major - John W McCreadie - William J Henley


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