Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XXIII (1927)
Harring, H. K.; Myers, F. J.
The rotifer fauna of Wisconsin. IV. The Dicranophorinae, pp. -Plate 49 ff. PDF (41.5 MB)
Letters. s then with nce became l to compare (gton and in rences were o how to ac- be found on e important Toidable; no e to prevent zrences were stances pres- re was very We knew Washington coastal Plain !olumbia, ac- ashington, is teau and the olidated cre- transported r e generally able amounts . The New ition of the nd; the sur- its extremely tV water is m carbonate, rmination of -bon dioxide. mned doubtful The differ- could always igin at once. ; entirely too ices between rotifers that Ith the varia- , I I Harring & Myers-Rotifer Fatna, of Wi.scov'sin.-IV. 673 The opportunity to study the rotifers of the state of Wis- consin offered a welcome opportunity to check what had already been learned. Geological conditions here are sub- stantially parallel to both Washington and Atlantic City; the southern part of the state is covered with Silurian and Ordovician limestones and dolomites, and the surface waters are hard. In the northern counties the last stage of glaci- ation removed all soils down to the Archean and Protero- zoic bed rock which the retreating glaciers eventually buried under 200-800 feet of till, derived from the siliceous Arch- ean rocks in adjacent portions of Canada; the water in the numerous lakes and ponds is everywhere soft. The re- sults of the rotifer collections agreed generally with what had been observed at Washington and in New Jersey; it was evident that rotifer distribution could not be correlated with dissolved calcium carbonate or total available carbon dioxide. About this time our attention was called to the work of Coville and Wherry on soil acidity and plant distribution. This seemed to offer a promising line of attack. Hydro- gen ion concentration was being demonstrated as very im- portant in physiological processes and, if it plays a part in plant distribution, the same effect might hold good for roti- fers. That this is really the case has been abundantly proved since systematic measurements of hydrogen ion con- centration have been made, and we believe that we are jus- tified in stating that rotifer distribution is directly depend- ent on it. Neutrality, or pH 7.0, seems to be the dividing line; above this, in alkaline waters, are found all the "cos- mopolitan" rotifers, enormous numbers, but relatively few species. A complete change occurs when the reaction drops below pH 7.0; the number of individuals is much smaller, but there seems to be no end to the number of spe- cies. This continues until the acidity becomes very pro- nounced, and at pH 4.0 but very few species of' rotifers re- main. Some numerical comparisons of acid and alkaline waters may be of interest. During three months collec- tions were made daily in alkaline waters of southern Cali- fornia, and 106 species were found; a single trip to Lenape Lake, near Atlantic City, made for the purpose of checking, netted 84 species. Exactly 100 species were collected in 43 I I
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