Cunnington (1920) in his work upon the African lakes 

 decided this question as follows: "There is finally 

 the problem of deciding whether forms recorded from 

 the neighborhood, but not actually from the waters 

 of a particular lake, are to be reckoned as belong- 

 ing to that lake 's fauna or not. I have dealt with 

 the difficulty in what seems the most common sense 

 way, by definitely including all forms recorded from 

 the drainage area of a lake as belonging to it. " The 

 same decision is adopted here and the localities out- 

 side of the lake itself may be designated first as the 

 mouths of tributary creeks and rivers, directly con- 

 nected with the lake, of which there are many a- 

 long both the American and Canadian shores. Then 

 there are small ponds, more or less removed from 

 the lake, whose outlets run into these tributary 

 creeks or rivers, and thus the ponds certainly be- 

 long to the drainage area of the lake. Neither the 

 tributaries nor the ponds appear upon the map, but 

 in the text the tributaries are designated by their 

 names and the ponds by the name of the creek or 

 river into which they empty. 



Breeding Areas of the Marginal Zone 



It has already been stated that the total bulk of 

 the plankton is large enough to feed a stock of fish 

 fry much larger than exists in the lake at the present 

 time. That statement is correct, but it is equally 

 true that a sufficient number of young fish by con- 

 stant eating could consume the original supply al- 

 though it might be exceptionally large. To obviate 

 this there must be some method of rendering the sup - 

 ply inexhaustible through a continuous replacement 

 of its elements as fast as they are used. This mar- 

 ginal zone supplies a sufficient number of natural 

 breeding grounds where both copepods and cladoc- 

 erans can and do multiply continuously under the 

 most favorable conditions. These areas are indicated 

 in figure 58 by hatched lines and it will be seen at 

 once that they practically surround the entire lake. 

 They separate naturally into 3 groups. 



There are first a large number of small areas in 

 the lake itself and close to the shore, whose shallow 

 waters contain abundant aquatic vegetation varying 

 with the depth of water and the kind of bottom. In 

 general these are more numerous and relatively larg- 

 er along the Canadian shore than on the American 

 side. Nearly every point which protrudes into the 

 lake from the Canadian shore is fringed on one or 



both sides with reeds and rushes or similar vegeta- 

 tion. And these furnish exceptionally good breed- 

 ing grounds for the cladocerans and for many of the 

 copepods, especially the Cyclo ps species. Examples 

 of such breeding areas are the eastern side of Point 

 Abino between Buffalo and Port Colborne and the 

 eastern side of Turkey Point on the shore of Long 

 Point Bay. At both places the lake is shallow for a 

 long distance from the shore, the bottom is hard and 

 solid so that the water seldom gets muddy, dense pat- 

 ches of rushes afford ample protection, and numerous 

 open spaces furnish the requisite amount of free- 

 swimming areas. Three copepods and 18 cladocerans, 

 besides many ostracods, amphipods, and insect larvae 

 were obtained ftom the Point Abino station. In the 

 open water at Turkey Point 4 species of Cyclops and 

 Diaptomus ashlandi were in considerable abundance. 

 The reeds and rushes, which extend far out into the 

 bay, sheltered 13 cladoceran species and numerous 

 insect larvae. 



These smaller areas, however, are not confined 

 to the Canadian shore; one is located at Stony Point, 

 Michigan. Epischura and Dia ptomus o regonensis were 

 exceptionally abundant there. Six species of Cyclops , 

 4 of Dia p tomus , a few Epischura , 12 cladocerans, and 

 a wealth of insect larvae, especially mayflies and 

 caddisflies were collected in the rushes. When we re- 

 flect that there are literally hundreds of similar small 

 areas scattered along the marginal zone around the 

 entire lake, we realize that they must make an im- 

 portant contribution to the permanence of the plankton. 



In addition to these smaller areas there are 3 very 

 large natural breeding grounds, which are also a part 

 of the lake itself, 2 on the Canadian and 1 on the 

 American shore. Together they represent an area of 

 more than 100 square mUes. The first of these is the 

 inner portion of Long Point Bay, which is designated 

 as "Inner Bay" upon large maps. This area is 8 miles 

 east and west and 5 miles north and south, with Port 

 Rowan at about the center of the western shore. The 

 deepest place in the area is charted as 6 feet, and 

 most of it is 3 feet or less in depth and very large 

 portions of it are covered with reeds and rushes. Near- 

 er the shore the aquatic vegetation includes cattails, 

 arrow -leaf, etc. , and is so dense that it is very dif- 

 ficult to penetrate for the collection of plankton. 

 Nine species of copepods and 23 cladocerans were ob- 

 tained from this bay, all of them in active breeding; 

 tows were taken at 3 different localities. To the 



149 



