134 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



shallow water near the shore is always much roiled by even moderate waves, appar- 

 ently by reason of line particles of clay suspended in it. A zone of this roiled water 

 extends for perhaps a quarter of a mile from the shore and disappears only in very 

 quiet weather. The temperature of the, water in August and September was 65° or 

 GG° F. There was but little difference between the bottom and top temperatures. 

 In the deepest water the difference was about 1°. 



The entire bottom of the lake is clothed with vegetation. The plants are, for the 

 most part, stoneworts of several kinds. There are also some flowering plants and 

 alg», all of them enumerated in the report of the botanist. * Together they make a 

 dense green carpet which appears to vary in thickness from 2 or 3 to G or 8 inches. 

 It harbors a rich bottom fauna and should be good pasture ground for such bottom- 

 feeding fish as the carp. 



As for the smaller animals and plants found in the lake the following summary is 

 sufficient. The net drawn at the surface showed usually S or 10 species of protozoa, 

 about 15 species of pelagic rotifers, 5 or species of Crustacea (cladocera and cope- 

 poda), and about 20 species of diatoms and other algai. A few fish larvae of unknown 

 species were taken, and occasionally there occurred a hydra, some insect larva? or pupa 

 skins, a snail or a worm, all evidently wanderers from the bottom. Alga?, rotifers, 

 cladocera, copepoda, and protozoa make up nearly the whole of the surface life. 



If the net be run in mid water or near the bottom, but in such a way as not to stir 

 up the bottom vegetation, very nearly the same result is obtained. The algae, the 

 protozoa, and the rotifers are, with few exceptions, of the same species as those living 

 in the surface water. A few ostracoda are now added to the Crustacea taken, and 

 occasionally an amphipod, both probably caught by the net as they left, for a moment, 

 their hiding-place among the plants of the bottom. An occasional annelid also 

 appears. 



If a dredge be used which stirs up the water plants and harrows up the bottom 

 the result is far different. All the forms previously noted are of course brought up 

 but in addition there are many that are peculiar to the bottom. The larger plants 

 growing on the bottom in deep water have already been mentioned. They are mostly 

 characea*, with some elodea, naias, and valisneria. A larger list of alga' is found and 

 includes several filamentous forms. The number of protozoa is greater and the list 

 of rotifers grows from 15 to about 60. It includes many fixed forms. Among the 

 Crustacea there is now a preponderance of ostracoda and amphipoda, though the 

 other groups are still well represented. The dredge brings up several sorts of 

 animals never found in the free water above. First are the mollusks, mussels which 

 are partly imbedded in the bottom, and many species of snails which are crawling 

 about over the plants on the bottom. Secondly, many sorts of insect larva', especially 

 those of the dragon-fiies and may-flies are dragged from their hiding-places on the 

 bottom. A third sort of animal found only in the bottom dredge are the water 

 spiders or hydrachnids. There are probably 3G sorts of these voracious little can- 

 nibals, and they are very numerous in individuals. In the fourth place, many worms 

 are found, some nematodes, many small oligoclweta, and a few leeches. A few 

 hydras and an occasional sponge or bryozoon complete the list of the bottom fauna. 

 Its striking elements are the mollusca, the insect larva', the water spiders, the worms, 

 the amphipod and ostracod Crustacea. 



*To be published in the Botanical Gazette and also as a bulletin of the Michigan Fish Commission. 



