Juday, Chancey (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XXI (1924)
Baker, Frank Collins
The fauna of the Lake Winnebago region, pp. -146 PDF (11.3 MB)
130 Wisconsin Academy of Sciences, Arts, and Letters. and bordered by marsh vegetation. Aquatic plants grow in the shallower parts of the river. Mollusks were most numerous near the shore on a sand or mud bottom in water 0.5 to 1 meter in depth. The Naiades are mostly different from the lake species as noted under Lake Winnebago species. The gastropods are mostly of species living in quiet habitats and there is not the variety found in the lakes, the latter being 50 per cent richer in species. Of the population of the river habitats Sphaerium striatinum makes up 67 per cent, forming great beds bordering the shore in many places. QUANTITATIVE ANALYSES OF THE FAUNA On rocky shores, a number of boulders were measured, the total animal life removed, and the area computed to the square meter unit. In the vegetation stations the total area covered by the plants was computed to the same unit. In several cases, as in Scirpus habitats, the unit included a column from surface to bottom. The population of Lake Winnebago compares favorably with that of any lake studied, being exceeded only by Oneida Lake among American inland lakes. The average number of animals per unit area on the different kinds of bottom in the two lakes mentioned is shown in table 2. It will be seen that among the Mollusca, Oneida Lake is 59 per cent richer, while among associated animals, Lake Winnebago is 9 per cent richer in individual population. The small population of the vegetation habitats in Oneida Lake is due to the fact that much of the population is included in the bottom areas which had an algal covering. Table 3 shows that Oneida Lake has a greater population per unit of area in the shallower water, but that Lake Winnebago has a greater population in the deeper water. Lake Mendota has a very small population in the shallow water as compared with the other lakes. Lake Butte des Morts has the largest population in the deeper water as well as the largest total population per unit area. The molluscan fauna of the Winnebago region is one of the most extensive and varied of any similar area yet studied. A total of 114 species and varieties of fluviatile and lacustrine forms were found, including three forms believed to be new to science. Table 4 shows the relative abundance of the molluscan fauna in the dif- ferent parts of this region.
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