Date of this Version
Reprinted from The Amerlcan Midland Naturalist, Vol. 84, No. 1, July 1970, pp. 59-68. University of Notre Dame Press, Notre Dame, Indiana
Ecological studies on the distribution of fairy shrimps have been made from 246 sites in the sandhills region of Nebraska. New records for Nebraska have been established for Artemia salina, Branchinecta campestris, B. lindahli, B. mackini and Cyzicus mexicanus. Seasonal populations of shrimp have been located in habitats containing permanent fish populations. Water mineralization was the dominant environmental condition related to the distribution of phyllopods with sodium and potassium compounds predominating in the strongly alkaline lakes. Several of the Artemia lakes were classified as hydroxide sites. Many of the alkaline ponds, where B. lindahli and B. campestris flourish, are chemically different from the sodium chloride waters common throughout the western United States.
The Nebraska Sandhill Region, an area of about 20,000 sq miles, is a plains environment that has been extensively modified by wind. It is a region of vegetated sandhills, sandy basins and valleys, with numerous exposed ground-water lakes and marshes of a permanent or seasonal nature (Fig. 1). An extensive limnological inventory of the aquatic habitats of the sandhills was undertaken between 1954 and 1961. This inventory was used to formulate a management program for sport fisheries (McCarraher, 1961). About 1640 lakes were investigated and an additional 850 permanent, smaller lakes less than 10 surface acres were recorded. In addition to permanent water, numerous seasonal pools were found. Periodic sampling of these permanent lakes and numerous seasonal ponds was carried out during all months of the year over a 12-year period from 1954 to 1968. This paper reports on the distribution of phyllopods in alkaline lakes of Nebraska and describes the quality of water and associated biota. The inland mineral waters of arid regions of the western United States have been designated as saline since sodium chloride is the principal solute with a pH value normally less than 8.8. In Nebraska's alkaline waters chloride salts occur in insignificant quantities. For this reason the term "salinity," used in describing marine or inland chloride and sulfate waters, is employed here as a collective term for all dissolved ionic constituents, with concentrations expressed as parts per million (ppm) .
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