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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. [109]-146 PDF (11.3 MB)

Page 130

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.
  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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