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 GASES DISSOLVED IN THE WATERS OF 
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 From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
 Proceedings of the Foiirth International Fishery Congress : : Washington, 1908 
 
 WASHINGTON :::::: GOVERNMENT PRINTING OFFICE 
 
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Digitized by the Internet Archive 
 in 2011 with funding from 
 The Library of Congress 
 
 http://www.archive.org/details/gasesdissolvedinOObirg 
 
GASES DISSOLVED IN THE WATERS OF 
 WISCONSIN LAKES ^ ^ ^ ^ ^ 
 
 From BUIvIvETlN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
 Proceedings of the Fourth International Fishery Congress : : JVashington, ipoS 
 
 }H^ 
 
 WAvSHINGTON 
 
 GOVERNMENT PRINTING OFFICE 
 
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 BUREAU OF FISHERIES DOCUMENT NO. 718 
 Issued May, 1910 
 
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 GASES DISSOLVED IN THE WATERS OF WISCONSIN LAKES 
 
 By Edward A. Birge 
 
 Secretary Wisconsin Commission of Fisheries 
 
 Paper presented before the Fourth International Fishery Congress 
 held at Washington, U. S. A., September 22 to 26, 1908 
 
GASES DISSOLVED IN THE WATERS OF WISCONSIN LAKES. 
 
 By EDWARD A. BIRGE, 
 
 Secretary Wisconsin Comtnission of Fisheries. 
 
 In the following paper I propose to sketch briefly a small part of the work on 
 lakes which the Wisconsin Geological and Natural History Survey has been 
 carrying on during the past four seasons. During 1907 and 1908 our investi- 
 gations have been aided by a grant of money from the United States Bureau 
 of Fisheries, which has enabled us to extend our field work much more than 
 would have been possible without this assistance. 
 
 LAKE DISTRICTS OF WISCONSIN. 
 
 The accompanying sketch map (fig. i) roughly indicates the position of 
 the lakes that have been studied. Wisconsin contains many hundreds of small 
 lakes, most of them lying in the moraines and found in hollows occasioned by 
 the melting of blocks of ice left during the glacial period. They occur in three 
 pretty well-defined districts, in the southeastern, the northeastern, and the 
 northwestern parts of the state. The water of the lakes in each district, though 
 varying much, shows a very definite general character, especially in the matter 
 of dissolved carbonates. 
 
 The southeastern lake district, as studied by us, extends from Waupaca 
 on the north to Lake Geneva on the south, and from the lakes at Madison to 
 Lake Michigan. Nearly 50 lakes in this district have been studied by our 
 survey, and almost without exception they contain considerable quantities of 
 dissolved carbonates, represented by 30 cubic centimeters to 50 cubic centi- 
 meters or more of carbon dioxide. Most of the work has been done upon these 
 lakes. Very numerous observations have been made upon Lake Mendota at 
 Madison, the headquarters of the survey, and some htmdreds of series of deter- 
 minations have been made on this lake at all seasons of the year. Much less 
 frequent observations have been made on a dozen or more other lakes in the 
 same region, giving a general picture of the annual cycle of gas changes of these 
 lakes, though not in the same detail as for Lake Mendota. '^ 
 
 a The diagrams accompanying this paper have been selected from a great number which have 
 resulted from the work of this survey, and are intended to illustrate some points in the distribution of 
 temperature, of the various gases, and of dissolved carbonates of lime and magnesium in the waters of 
 Wisconsin lakes. In all diagrams the vertical spaces represent the depth in meters. The horizontal 
 spaces represent either degrees centigrade in the case of temperature, or cubic centimeters of gas per 
 liter. The line marked " T" indicates the temperature; oxygen is marked " O " ; nitrogen, " N " ; carbon 
 dioxide, "C"; and carbonates, "Cb." In the diagrams which show nitrogen, both*his gas and oxygen 
 were determined by boiling. In those without nitrogen, the oxygen was determined by titrating 
 according to Winkler's method. The alkalinity or acidity of the water were determined by titrating 
 
 1275 
 
1276 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 In the northeastern part of the state is a district somewhat triangular in 
 shape, measuring roughly some 30 miles on each side, and containing several 
 
 3. I. — Sketch map of Wisconsin, showing lake distric 
 directly north of "G". The Oconomowoc di 
 ary. Hammills Lake in northwestern Wisconsin 
 
 . Green Lake lies 
 the southern bound- 
 
 with Standard solutions of HCl or Na^COg, with phenolphthalein as an indicator. The result is expressed 
 in the diagrams in cubic centimeters of CO2 per liter, acidity being shown as free CO,, while alkalinity- 
 is represented by platting the number of cubic centimeters of COo that would be required to bring about a 
 neutral reaction. Where the line indicating the CO2 passes to the left of the zero line, it indicates that 
 the water is alkaline. 
 
 The amount of dissolved carbonates was determined by titrating with HCl, with methyl orange as 
 an indicator. It is represented in the diagrams by the number of cubic centimeters per liter of CO2 set 
 
GASES. IN WATERS OP WISCONSIN LAKES. 
 
 1277 
 
 
 
 8101 
 
 N 34 36 38 40 
 
 14 16 16. ^0 22 
 
 hundred small lakes. About 60 of the more important and deeper lakes 
 in this region have been studied during the summer. The survey has found 
 that the month of August and the early part of September represent the 
 critical period for the distribu- 
 tion of gas in lakes, and that „ ^n^ 9 
 from observations made at this °r 
 time the general history of a lake 
 may be inferred when the cycle 
 is known in detail from a num- 
 ber of lakes which may serve as 
 standards. The lakes of north- 
 eastern Wisconsin contain, in gen- 
 eral, soft water, the carbonates 
 being much lower than in the 
 southeastern lakes — frequently 
 not more than one-sixth as great 
 and not infrequently less than 
 one-tenth. 
 
 The lakes in the northwestern 
 district are scattered in two some- 
 what ill-defined elongated seiies 
 extending north and south for a 
 distance of 70 miles or more. 
 Between 50 and 60 of these lakes 
 also have been examined. Their 
 water is intermediate in character 
 between that of the two other 
 districts, the content in carbon- 
 ates averaging nearly one-half 
 as great as that of the south- 
 eastern lakes. 
 
 "iG. 2. — Lake Mendota. Vertical distribution of gases, carbonates, 
 and temperature, January 26, 1906. C, carbon dioxide ; C 
 ates of lime and magnesia; N, nitrogen; O, oxygen; T, tempera tu 
 See footnote. 
 
 GASEOUS CHANGES IN LAKE MENDOTA. 
 
 Let me begin my account by a short sketch of the cycle of changes in Take 
 Mendota. Figure 2 shows the condition under the ice in early winter. The 
 
 free from the monocarbonates. Since, in the lakes of southeastern Wisconsin, the amount of dissolved 
 carbonates is considerable, the numeration of the horizontal scale is interrupted in order not to make 
 the diagram too large. For instance, the numbers at the top of figure 2 change abruptly from 22 to 34. 
 The larger numbers refer solely to the line Cb, indicating the number of cubic centimeters of COj 
 represented in the monocarbonates. A similar arrangement will be seen in other diagrams. 
 
 The points at which observations were taken are indicated by small circles in the lines of the dia- 
 grams. The lines are drawn directly from one point of observation to the next, no attempt being 
 made to round ofT the curves. 
 
1278 BUIvLETiN OF THE BUREAU OP FISHERIES. 
 
 temperature is nearly the same at all depths, rising from less than one degree 
 just below the ice to something over one degree at the bottom. The water con- 
 tains about 9 cubic centimeters of oxygen per liter, except in the bottom, where 
 it has begun to disappear under the action of decomposition. Nitrogen is present 
 to about the amount required to saturate water at the given temperature. The 
 reaction of the water is neutral or slightly alkaline at all depths. Carbonates 
 
 are present to an amount rep- 
 resented by about 38 cubic 
 centimeters of carbon dioxide 
 per liter. 
 
 As the winter advances (fig. 
 3) some changes occur under 
 the ice . The temperature rises 
 slowly at all depths, but most 
 rapidly at the bottom. Slow 
 decomposition goes on in the 
 deeper water, where also the 
 greater part of the fish are 
 found. There thus results a 
 reduction of the amount of 
 oxygen, which may nearly or 
 quite disappear at the bottom, 
 and a corresponding develop- 
 ment of carbon dioxide, so 
 that as winter advances the 
 bottom water may contain 
 considerable quantities of free 
 carbon dioxide. The reaction 
 of the upper water becomes 
 much more markedly alkaline 
 than in the early winter, a 
 change probably due to the in- 
 fluence of the growing plants. The carbonates may or may not decrease in the 
 water immediately below the ice. If a diminution is found (and such decrease 
 may be very pronounced, as in fig. 4), the change is due to the accumulation 
 beneath the ice of water resulting from the melting of the ice or snow and 
 containing, therefore, less dissolved matter than the water of the lake usually 
 holds. As the season advances a rapid growth of algae may take place beneath 
 the ice, resulting in a considerable increase of the oxygen, which may carry 
 it beyond the point of saturation. This increase is usually accompanied by a 
 considerable increase in the alkalinity of the water (fig. 4) . 
 
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GASES IN WATERS OF WISCONSIN LAKES. 
 
 SPRING AND SUMMER. 
 
 When the ice has disappeared in the spring (fig. 5) , the water is once more 
 mixed throughout the entire depth, and uniform conditions are again estab- 
 Hshed. The reaction becomes almost or quite neutral. Oxygen is present to 
 about the point of saturation, although, in figure 5, some trace of the winter's 
 diminution of oxygen is still present at the bottom. Carbonates and nitrogen 
 are distributed about uniformly at all depths. As the spring advances and the 
 algae begin their spring growth, the reaction of the water becomes increasingly 
 
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 Tk;. 4. — Lake Mendota, March 29, 1906. 
 
 alkaline. (Fig. 6.) The temperature rises, and soon the surface gains so 
 rapidly in warmth that the wind is unable to distribute the surface water 
 throughout all depths; the circulation becomes increasingly restricted, and sum- 
 mer conditions begin to develop. The temperature curve (fig. 7) shows a 
 marked difference between surface and bottom temperatures, and indicates a 
 temporary thermocline at the depth of 10 meters or more. Corresponding to 
 this stratification of the water and consequent shutting off of the lower water 
 with direct contact with the air, the oxygen in the lower water begins to decline 
 
I28o 
 
 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 and free carbon dioxide begins to appear there. This process is accentuated as 
 summer approaches. (Fig. 7 and 8.) The amount of free carbon dioxide 
 increases, the thickness of the stratum of the water whose reaction is acid 
 increases also, and the oxygen steadily and rapidly declines in the lower water. 
 By the early part of July the permanent summer conditions of temperature are 
 found. (Fig. 8.) The regular summer thermocline is found lying, in general, 
 between 5 meters and 10 meters. Oxygen has disappeared wholly from the bot- 
 tom waters, and is rapidly going from 
 all parts of the lake below the ther- 
 mocline. The water has divided into 
 an upper warm stratum containing 
 an abundance of oxygen and with an 
 alkaline reaction, and a lower, colder 
 layer with free carbon dioxide, and 
 little or no oxygen except in the ex- 
 treme upper part. 
 
 LATE SUMMER AND AUTUMN. 
 
 By the first of August this con- 
 dition has reached its maximum. 
 (Fig. 9) . The lake contains no oxy- 
 gen below a depth of 10 meters. 
 Above that level, in the warm water 
 and in the uppermost part of the ther- 
 mocline, there is abundance of oxygen 
 for animal life. Beneath that depth 
 no active animal life is found in the 
 water,'' though the inhabitants of the 
 mud remain alive through this period, 
 some of them in an inactive condi- 
 tion and some in a partially active 
 state . The carbonates show the char- 
 acteristic summer condition, in which 
 the upper water contains a smaller amount than the lower, the transition coming 
 in rapidly at the thermocline. This condition persists through August and early 
 September for a period varying with the warmth of the season. As the tem- 
 perature of the water begins to fall, the thermocline moves downward under 
 the action of the wind, and this process increases the extent of circulating water 
 and in like degree the thickness of the layer containing oxygen. Figure 10 
 illustrates this condition in early October. The cold weather and winds which 
 are apt to occur at about this time soon bring about a complete mixture of the 
 
 « Except Corethra larvae, whose presence is an apparent rather than a real exception. 
 
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 —Lake Mendota, April 8, 1906. 
 
GASES IN WATERS OF WISCONSIN LAKES. 1 28 1 
 
 water (fig. 11) ; and with it returns the condition of uniformity which we found 
 at the opening of winter. From this time until the lake freezes the temperature 
 declines almost uniformly at all depths; the amount of oxygen increases as the 
 capacity of the water to hold it rises with the fall in temperature; and the 
 water becomes almost or quite neutral as the vigor of the growing algse 
 declines and as decomposition becomes slower in the cooling water. 
 
 From this brief account it is plain that the cycle of gas changes in Lake 
 Mendota is a very important factor in determining the conditions and possibilities 
 of life in that lake. Here is an inland lake, one of the largest in Wisconsin, 
 
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 Fig. 6. — Lake Mendota, May 4 
 
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 . — Lake Mendota, May 21 
 
 Cb 
 
 about 9 kilometers in length and 6 kilometers in breadth, with a maximum 
 depth of 24 meters and an average depth of about 12 meters, the lower half 
 of whose water is wholly uninhabitable during middle and late summer and 
 early fall. This water in the early spring is saturated with oxygen, as is the 
 lower water of all lakes, but the supply is not great enough to meet the demands 
 which are made upon it. The lake is peculiarly rich in plankton, and the 
 decomposition of the great amount of animal and vegetable debris which is 
 showered down from the upper waters into the lower soon exhausts the oxygen 
 supply and renders the lower water unfit for the maintenance of higher life. 
 
1282 
 
 BUIvIvETlN OF THE BUREAU OF FISHERIES. 
 
 Thus the vital conditions in one part of the lake very sharply limit the possi- 
 bilities of life in another portion. None of those fish which demand a refuge 
 in the cold bottom water during the summer can live in Lake Mendota, nor is 
 it possible to find there those members of the plankton which belong only in 
 the deeper and colder water. 
 
 It is perhaps unfortunate for some reasons that Lake Mendota was necessarily 
 the lake on which the most numerous observations were made, since this lake 
 offers an extreme case in the matter of loss of oxygen from the lower water. 
 The oxygen disappears more quickly and fully than in any other Wisconsin lake 
 
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 Fig. 8. — Lake Mendota, July 2, 1906. 
 
 of approximately equal size and depth. The area of the lake is so large that the 
 bottom water has necessarily a relatively high temperature, and the plankton 
 is so abundant that the lower water is continually receiving great quantities of 
 decomposable matter. Moreover, the thermocline lies comparatively deep 
 because of the large size of the lake, so that the volume of the cooler water is 
 correspondingly reduced. All of these causes combine to make the disappearance 
 of the oxygen very complete and unusually rapid. This lake therefore affords 
 less opportunity than do other bodies of water for the study of the process in its 
 details. 
 
GASES IN WATERS OF WISCONSIN LAKES. 
 
 1283 
 
 GASES AND CARBONATES OF OTHER LAKES IN SOUTHEASTERN WISCONSIN. 
 
 We may contrast the summer conditions in Lake Mendota with those that 
 obtain in the deepest inland body of water in Wisconsin, Green Lake. This 
 has a maximum depth of 72 meters, with length of about 12 kilometers and a 
 breadth of 4 kilometers. Figure 12 shows the conditions found in Green Lake 
 on October 4, 1906. The volume of water is so great that summer conditions 
 of temperature still remain, and cooling has proceeded to no great depth. The 
 water shows the characteristic summer condition of an alkaline upper stratum. 
 
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 Fig. 9. — Lake Mendota, August i, 1906. 
 
 with the cooler water acid. The dissolved carbonates are low in the warmer 
 waters, rapidly increasing at the thermocline, and then remaining nearly con- 
 stant till the bottom of the lake is almost reached, where there is again an 
 increase. The oxygen shows a marked diminution in the thermocline (ii 
 meters to i6 meters) ; it then slowly increases in quantity with the depth until 
 a maximum is reached at about 40 meters, which remains for some 10 meters; 
 and the amount of the gas then declines until it is nearly or quite exhausted at 
 the bottom. The diagram shows plainly the effect of life and death on the 
 oxygen where it is found in abundance in a large volume of water. The oxygen 
 
BULLETIN OF THE BUREAU OF FISHERIES. 
 
 1284 
 
 curve shows that two of the regions where chemical action is going on most 
 vigorously are the thermocline and the bottom water. The accumulation and 
 decomposition of the plankton in the lower water is a sufficient explanation 
 for the changes which take place there. The reduction at the thermocline is 
 apparently due to the fact that the algae, as they begin to die and sink, often 
 remain for some time at the thermocline. The cool water apparently causes 
 their life to be prolonged, and while certain parts of the filaments are dead 
 and decomposing, others still retain sufficient vitality ,to keep the plant from 
 ^. sinking. When this period is 
 
 .0. - - ,0 _ ._._.. .T _ 30 32 34 36 38 40 passed, the plant sinks steadily 
 
 and rather rapidly to the bot- 
 tom, thus consuming compara- 
 tively Httle oxygen on the jour- 
 ney. Many forms of plankton 
 animals also accumulate in the 
 thermocline, finding there more 
 food than in any other part 
 of the cool water. Both these 
 causes, then, lead to a diminu- 
 tion of the oxygen at this point. 
 It must not be supposed that 
 there has been no loss of oxygen 
 in the lower water where it is at 
 a maximum. In early spring 
 this water would have corftained 
 between 8 cubic centimeters and 
 9 cubic centimeters per liter, so 
 that at least one-third of the 
 original stock has been con- 
 sumed. 
 
 Green Lake is the only lake 
 in Wisconsin that shows so small 
 a reduction of the oxygen of the 
 lower water. Lake Geneva, near the southern boundary of the state, has about 
 the same dimensions as Green Lake; it is the second deepest lake in the State, 
 having a depth of 41 meters. The late summer conditions are shown in figure 
 13, where the same general facts are visible as in Green Lake; but the oxygen is 
 much more reduced and shows only a trace, or is altogether absent, from the 
 depth of 33 meters to the bottom. In North Lake, one of the Oconomowoc 
 group, consumption of oxygen at the thermocline goes on more rapidly, and 
 sometimes leads, as is shown in figure 14, to the disappearance of the oxygen 
 from that stratum, while some of the gas still remains at a greater depth. 
 
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 —Lake Mendota, October 8 
 
GASES IN WATERS OF WISCONSIN LAKES. 
 
 1285 
 
 This lake has an area of about 51 hectares (126 acres) and a depth of about 
 22 meters. It contains an abundance of oxygen in the water above the ther- 
 mocHne; then follows a stratum in which the gas has almost or quite disap- 
 peared; then comes one containing a small amount, but sufficient for the 
 maintenance of a large number of plankton animals; and beneath this to the 
 bottom the water contains no oxygen. A little later, in September, all of the 
 oxygen will have disappeared from the lower water, and the region beneath the 
 thermocline will become uninhabitable by animal life. 
 
 LAKES OF NORTHEASTERN WISCONSIN. 
 All of these illustrations are taken from the lakes of southeastern Wiscon- 
 sin, where, as shown by the diagrams, the dissolved carbonates are present 
 in large quantities, and where the 
 
 CO T 
 
 Cb 
 
 28 30 32 J4 36 
 
 plankton life is correspondingly abun- 
 dant. In the lakes of northeastern 
 Wisconsin, where the carbonates are 
 low, the average quantity of plank- 
 ton is much less than in the hard- 
 water lakes. It is not true that the 
 plankton of every soft-water lake is 
 smaller than that of every hard- water 
 lake. The lakes of both types differ 
 among themselves very greatly, but on 
 the average the statement is entirely 
 correct. European observers have 
 found the same thing for the fish in 
 the lakes of Switzerland that we have 
 found for the plankton in Wisconsin. 
 We have also found that there are 
 fewer fish in the northern lakes than 
 in the southern, hard- water lakes. In 
 these northern lakes, therefore, with 
 their poorer plankton, the oxygen per- 
 sists longer than in the southern ones. 
 It may disappear entirely , but it usually 
 lingers late, and in the deeper lakes it 
 is apt to remain throughout the season. 
 
 The diagrams of Thousand Island Lake and Stone Lake (fig. 15, 16) show 
 the summer condition in two of the larger and deeper lakes of this type. The 
 carbonates in both are low, representing about 9 centimeters and 3 cubic 
 centimeters of carbon dioxide, respectively. The upper water is acid, or nearly 
 neutral, the acidity increasing below the thermocline. The oxygen curve of 
 Thousand Island Lake closely resembles that of Green Lake, having a depression 
 
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 —Lake Mendota, October ii, 1906. 
 
1286 
 
 BUI^IvETlN OF THE BUREAU OF FISHERIES. 
 
 at the thermocline, and an increase in the deeper waters, followed by a gradual 
 decrease to the bottom, where the oxygen is nearly or quite exhausted. This 
 Thousand Island Lake is one of the lakes in northeastern Wisconsin that contain 
 
 lake trout {Cristivomer namaycush). 
 The fish inhabits the bottom water 
 during the summer, and seems to be 
 found native only in lakes which carry 
 an abundance of oxygen to the bot- 
 tom. The oxygen curve of Stone 
 . Take (fig. 1 6) shows another interest- 
 ing fact which is observable in many 
 inland lakes, namely, an increase of 
 oxygen in the upper part of the ther- 
 mocline. This is due to the presence 
 of algae at this depth, which still re- 
 ceive sufficient light to manufacture 
 starch, and liberate oxygen in that 
 process. This phenomenon is very 
 commonly found in our lakes, but by 
 no means universally. The crops of 
 algae, which produce oxygen, are not 
 necessarily continuous ; nor is oxygen 
 produced in quantities beyond con- 
 sumption at all periods of their growth. 
 The thermocline may lie so deep or 
 the water may be so opaque that 
 algae in the cool water do not get 
 light enough to enable them to produce 
 starch. Neighboring lakes, therefore, 
 which seem quite similar, may or 
 may not show this rise of the oxygen. 
 In the same lake it may appear and 
 disappear during the season, and 
 although usually present at a corre- 
 sponding time in successive seasons 
 may vary greatly in amount. One 
 common result of this process is the 
 using up, at this point, of the carbon 
 dioxide, the fact being shown by a reduction of the acidity, or an increase 
 in the alkalinity, of the water. The contrast between the carbon dioxide 
 curves in Thousand Island and Stone lakes is sufficiently noteworthy, and this 
 difference is apparently due to the activit}'- of the algae at a depth of 9 meters 
 
 
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 — Green Lake, 
 
6 4 2 2 4 
 
 GASES Ii-^ WATERS OF WISCONSIN LAKES. 1 287 
 
 and 10 meters in Stone Lake, and the consequent using up of the supply of free 
 carbon dioxide. 
 
 MANUFACTURED OXYGEN. 
 
 In other lakes this process goes on much more vigorously than it did in 
 Stone Lake. An illustration may be given from Beasley Lake, a little body 
 of water in the Waupaca chain (fig. 1 7) , where the oxygen at the thermocline 
 rises to the maximum of about 15 cubic centimeters, and where its presence 
 is accompanied by a marked increase of the alkalinity of the water. 
 
 It must be remembered that ^^ 
 
 both the amount of oxygen and 
 of alkalinity represent the al- 
 gebraic sum of numerous com- 
 plicated processes . The amount 
 of oxygen is determined not 
 only by the quantity manu- 
 factured, but also by that con- 
 sumed, and the quantity or 
 deficiency of carbon dioxide 
 depends on the relation of the 
 rate of the manufacture of 
 starch to the rate of the de- 
 composition of the plankton. 
 The two processes are not nec- 
 essarily parallel, and we not in- 
 frequently find, as is shown in 
 figure 18, a great excess of 
 oxygen, while the carbon di- 
 oxide curve shows no traces of 
 the process which has manufac- 
 tured it . In the soft- water lakes 
 whose reaction is usually acid, 
 the manufacture of oxygen in 
 the cooler water may cause a change in the reaction of the water. This is 
 illustrated by Silver Lake (fig. 19), a small pond in northeastern Wisconsin, 
 where the oxygen maximum occurs at 7 meters, and at the same depth the 
 reaction changes from a positive acid to an equally positive alkaline one. It 
 returns to a slight acidity at 9 meters, and from this point the amount of free 
 carbon dioxide rapidly increases. 
 
 In the smaller and shallower lakes the presence of this manufactured oxygen 
 at the thermocline region is often of great importance in extending the inhab- 
 itable region. Beasley Lake is perhaps the best illustration of this fact. The 
 
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 Fig. 13. — Lake Geneva, September 2 
 
BULLETIN OF THE BUREAU OF FISHERIES. 
 
 lake contains a great amount of fermentable material, and the oxygen disappears 
 from the bottom water early in the spring. The lake is so small that the ther- 
 mocline lies very close to the surface, remaining at 4 meters or above until late 
 in the summer. Were it not for the manufactured oxygen, the entire body 
 of water below the thermocline would be uninhabitable. The maintenance of 
 the stock of this gas by the presence of the algae doubles the thickness of the 
 habitable stratum during the summer and the early part of the autumn. Figure 
 1 7 also shows the effect of the manufacture of oxygen on the dissolved carbon- 
 ates; but that matter is too complex to be discussed here. 
 
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 —North Lake, east part, July 30, 1906. 
 
 I have spoken of Thousand Island Take as a characteristic " lake-trout lake." 
 So far as our observations go, the lake trout in northeastern Wisconsin is found 
 only in lakes of this type; yet observations made in the summer of 1908 in north- 
 western Wisconsin show that the fish can exist in lakes of a type which would 
 seem to be unfavorable to it. I give a diagram of the conditions in Hammill's 
 Lake (fig. 20) , a small body of water in northwestern Wisconsin, which contains 
 a few lake trout that have been introduced. Their presence in the lake shows 
 that they can exist in a body of water in which the oxygen extends some distance 
 
GASES IN WATERS OF WISCONSIN LAKES. 1 289 
 
 into the cooler stratum, although the bottom water is practically or wholly devoid 
 of the gas. Their presence in small numbers shows that such a lake is not suited 
 to the species, and that, while it can adjust itself and survive under these unfa- 
 vorable conditions, it is unable to thrive. It is not known whether it spawns 
 tmder these conditions. There can be little question that the continuance of the 
 species in this lake is due to the fact that the cool water still retains a certain 
 amount of oxygen throughout the season. 
 
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 Fig. 16. — Stone Lake, 2 
 
 CONCLUSIONS. 
 
 I have selected for illustration these series from among the hundreds of 
 similar observations that have been made by the Wisconsin Geological and Nat- 
 ural History Survey. I have not attemped to give any complete picture of the 
 story of the gaseous changes in any lake, and many of the most important rela- 
 tions and results have been left unmentioned. I have brought these cases to 
 your attention in order to illustrate two conclusions which are of importance. 
 The first is that the cycle of the gaseous changes in a lake illustrates more 
 readily and more conspicuously than perhaps any other facts could do what 
 maybe called the "annual life cycle" of the individual lake, showing both the 
 
1 290 
 
 BUIvLETiN OF THE BUREAU OF FISHERIES. 
 
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 underlying resemblances of that cycle as found in different lakes and also some 
 small part of the infinite variation in its details. These diagram.s from late 
 summer represent the culminating point of an annually recurrent series of defi- 
 
 nite changes through 
 C 36 38 40 42 44 which the lakes pass with 
 
 the season as certainly as 
 the season returns. These 
 changes result from the 
 interrelation of the living 
 beings of the lake with an 
 environment strictly lim- 
 ited in its space and con- 
 taining only definite 
 amounts of food and of 
 oxygen, to which only 
 small additions can be 
 made from the outside. 
 The story of these changes 
 is legible to him who will 
 closely follow it. Its de- 
 tails differ, indeed, in each 
 lake from those found in a neighboring lake, but on the whole it always follows 
 along certain great lines and shows that lakes can be grouped into classes 
 according to its maj or vari- _ , 
 
 ants. Only a little of this C _ _ Q ^ _ . . . T_ _ 34 36 
 
 story is now known, and 
 many years of detailed 
 work will be needed be- 
 fore even its larger facts 
 are fully ascertained and 
 justly interpreted. But 
 from the few diagrams 
 which I have given one 
 may see that lakes present 
 to the student a vital 
 story, as definite, as vari- 
 able, and as complex as 
 is that of a living organ- 
 ism; a story to be followed by means like those needed to work out biological 
 life histories, and one whose interest is such as to claim far more attention 
 from science than it has received. 
 
 Fig. 17. — Beasley Lake, August 4, 
 
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 —otter Lake, August 4 
 
GASES IN WATERS OF "^^SCONSIN LAKES. 
 
 I29I 
 
 PRACTICAL IMPORTANCE OF THE SUBJECT. 
 
 If this scientific interest were all that the story affords, however, I should 
 not have brought it to the attention of this congress, whose interest rightly lies 
 in the fisheries. But these changes, which go on in the water of the lake, affect 
 not only the life of lower organisms but also that of the higher ones, including 
 the fish. No facts of environment show more clearly than do these how life 
 determines its own conditions. On the presence of a large or a small quantity 
 of plankton in the upper waters may depend the conditions which make the 
 lower water habitable or uninhabitable. The relation between the volume of 
 the lower water and the quantity of decomposing matter discharged into it 
 
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 Fig. 19. — Silver Lake, August 2 
 
 determines whether this lower water shall be filled with animal life and support 
 a relatively abundant population of lake trout and whitefish, or whether life of 
 all kinds shall cease abruptly at the thermocline, or whether a scanty plankton 
 shall indeed leave abundance of oxygen in the lower water but provide a supply 
 of food for a scanty higher life. Thus the annual history of the lake discloses 
 facts that are fundamentally important in determining the amount and kind of 
 life which the lake may support and that which may wisely be introduced into it ; 
 and it becomes plain that a knowledge of them is indispensable to an intelligent 
 use of the waters of the lake by those concerned in increasing the supply of fish. 
 In other words, it seems clear that a knowledge of lacustrine physics and 
 chemistry is just as necessary to the best economic utilization of the waters of 
 
1292 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 the lakes as a knowledge of soil physics and chemistry is to the best agricultural 
 use of the land. The problems of the lakes are complex and are not easily 
 solved, but they are far less complex and much more easily solved than are the 
 corresponding problems of the soil. This nation and the several states are 
 spending hundreds of thousands of dollars annually in studying the soil. This 
 expenditure is fully justified, not only by its scientific results but also by its 
 practical consequences. Little or no time or money is now devoted to the 
 similar study of the waters of the lakes. Yet no one who has followed investi- 
 gations of this kind can doubt that if the lakes could be studied on the same 
 large scale and with the same careful methods as those applied to the study 
 of soils, results of great economic value would be obtained. It was years before 
 the study of physics and chemistry of soils promised large economic results. 
 Valuable practical hints have already come from the brief and imperfect study 
 of the lakes which our survey has made, and the present situation of our knowl- 
 edge indicates that a wider and more systematic study than we have been able 
 to undertake would ultimately lead to far larger and more important con- 
 clusions. Such a study is greatly needed. The culture of fish in the innumer- 
 able inland lakes of this country should rest on the basis of scientific knowledge 
 at least as broad and as complete as that which underlies the cultivation of our 
 farm products. We who have in charge the maintenance of a public interest 
 so extensive and valuable as is that of the fisheries are most of all concerned 
 in the acquisition of that knowledge which is the only true guide of practical 
 affairs. 
 
DISCUSSION. 
 
 Mr. J. J. Stranahan (U. S. Fisheries Station, Bullochville, Ga.). I would like to 
 ask Professor Birge a question or two. It is not closely related to this subject, although 
 not entirely foreign. I desire to ask if you have had any experience as to the plankton 
 and the relative amount of crustaceans and other animal life that is in soft and hard 
 waters. 
 
 Professor BirgE. Yes; although the matter can not be finally settled. It is a 
 condition well known to European investigators. The hard-water lakes are much 
 richer in plankton on the average than the soft -water, but you can not make the state- 
 ment that every hard-water lake has more plankton than any soft-water. 
 
 Mr. Stranah.an. At Guilford, in England, south of London; at Castalia, in Ohio; I 
 think at Northville, in Michigan, and wherever I have known of exceedingly hard water, 
 full of lime and other salts, there has been an excess of plankton. I collected plankton at 
 CastaUa to take to the World's Fair at Chicago, and with pretty carefully conducted 
 weights the amount of crustaceans exceeded the amount of mosses and aquatic plants 
 in which they were congregated when taken from the water. That water is so rich in 
 lime and magnesia that it makes stone of a shingle in a year, and that is probably the 
 greatest trout preserve in the world. At Bullochville, Ga., where I am now, our water is 
 practically aqua pura; we can use it in photographic processes; it is exceedingly soft. 
 We have put mollusks in it, but the different little periwinkles and other shell-covered 
 species die in a few months, and it is not conducive to fish culture. We took two 
 carloads of cement and buried it in our spring, and we thought we could see a marked 
 increase in the growth of some kinds of vegetation, to say nothing of small water animals 
 that grow in it. So I am a great stickler for the idea that we ought not to put fish 
 hatcheries where there is not a large amount of calcareous material in the water. 
 
 Professor Birge. I wanted to talk about that, but with the Hmitations on the 
 time I could hardly get to that part of the subject. 
 
 Doctor NoRDOvisT. Those investigations Professor Birge has made are of the 
 greatest importance in fish culture in lakes. I am of the same opinion as Professor 
 Birge, that many of the disappointments that we have in fish culture are due to lack of 
 knowledge about the amount of oxygen and the biological conditions of the lakes. 
 
 I would only ask Professor Birge about some slight points here in his investi- 
 gations. At what time in the day was the amount of oxygen determined? 
 
 Professor Birge. We have made a great many attempts to discover diurnal 
 variations in oxygen, but it is a very rare thing to find any difference in the results 
 obtained from tests made in early morning, late afternoon, and late evening. We 
 have continued the tests throughout the twenty-four hours. We have found very 
 small, hardly perceptible, diurnal differences. I have received, since I came to this 
 congress, a letter from my assistant, Mr. Juday, to whom much of this work is due, 
 telling me that he had found such a difference in Lake Mendota. 
 
 Doctor Nordovist. That is just what I mean with reference to the investigations; 
 it ought to show a dift'erence, and I think that the curve that you have given in many 
 of your lakes at the depths of six, seven, to ten meters may perhaps 
 
 Professor Birge [interrupting]. We have spent from two to three weeks hunting 
 for diurnal changes right on that point. I put a party on those lakes — Otter Takes — 
 and we got negative results all the time; the curve remained substantially the same. 
 
 1293 
 
1294 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Doctor NoRDQVisT. It is very interesting to hear that. Then I would be glad to 
 learn in what way the oxygen was determined. 
 
 Professor BirgE. In two ways: One diagram showed an oxygen line determined 
 by boiling; and in the other it showed oxj'gen by Winkler's method of titration, or by 
 one of the modifications of Winkler's method, which is a standard in the books. 
 
 Doctor NoRDOVisT. Oxygen by the Winkler method? 
 
 Professor BirgE. Yes, depending on the liberation of iodine and sodium at the end. 
 
 Doctor NoRDOViST. How was the water taken up? 
 
 Professor BirgE. The water was taken up by a pump and hose, the latter being 
 lowered to the proper depth, and the water brought up and kept completely out of 
 contact with the air, so that where there was no oxygen we had like results always. 
 
 The President. Are there others who will contribute to the discussion of this most 
 interesting paper? 
 
LIBRARY OF CONGRESS « 1 
 
 III 
 
 10 029 714 161 2! 
 
 
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