418 Wisconsin Academy of Sciences^ ArtSf and Letters. 
PAET III. ECOLOGY OF THE LAKE. 
I. ECOLOGICAL ZONATION. 
The general ecological zonation has been discussed in part I 
of this paper. But for the sake of comparison the following 
summary of the vertical and horizontal sections of the lake is 
offered: 
Area 
fEulittoral 
(Euphytal) 
Littoral 
(Phytal) 
Aphytal. 
Sublittoral 
. (Dysphytal) 
Vertical Section 
Depths 
fl. Shore line (inch 
bars) 
0— Im. 
—Shoals 
4-1 m. 
2. Surf line 
(Rachion) 
1 m. 
Upright 
14-5 
13. Vegeta- 
tionZone 
Recum¬ 
bent 
4-6 m. 
.Barrens 
Patches 
—Rock Reefs 
3-8 
4. Shell Zone 
6-8 
5. Aphytal Zone 
7-25 
Horizontal Section 
Rocky—barren 
Stony—barren 
Sandy—barren 
Sandy—sparse veg. 
Stony—barren 
Potamog-eton, Najas, 
Vallisneria 
Chara, Myriophyllum, 
Ceratophyllum, Pota- 
mogeton. 
Plant, marl., sand, 
stones 
Rock, with encrusta¬ 
tion 
Shell, sand, mud-barren 
Mud, with admixture of 
deflux, (shell, ooze, 
etc. organic and cop- 
rogenic sediment) 
Practically the entire macrofauna of the lake, except the fish, 
is bound to one or other substratum; fish, too, show certain habi¬ 
tat preferences conditioned through food, or through reproduc¬ 
tion, which delimit their distribution. Since the physical agents 
operate on the substrata, it is through the latter that we must 
study the ecological habitat. 
In a study such as the present it becomes necessary to make 
sweeping statements without considering possible, and more 
probable, exceptions in the way of habitat preferences and asso¬ 
ciations. These preferences are deduced largely from the quan¬ 
titative averages. While a quantitative method tends toward 
exactness, it carries with it an element of uncertainty in that it 
necessarily restricts itself to the exploration of a very definitely 
circumscribed area; hence qualitative catches have been used to 
supplement the findings. 
