Sewage Works Planning
EASTERN WISCONSIN LAKES AS RELATED TO FERTILIZATION
II. Productivity
By Jam es B . Lackey
S e n io r B io lo g is t, U n ite d S ta te s P u b lic H e a lth S e rv ic e , C in cin n a ti, Ohio
Those unused plants we term weeds, growing on a tennis court or in a cotton field, have a high, easily recognized nuisance quality. The sur
face waters of lakes frequently support a huge crop of floating or sus
pended microscopic plants, along with occasional minute animals.
These may be weeds as far as their nuisance quality is concerned. By definition such floating or suspended forms are termed plankton; there is a standing crop of plankton in lake waters at all times, and local or short-lived dense aggregates are usually referred to as blooms. Some plankton is desirable; some blooms are highly objectionable. Blooms usually occur in lakes that are relatively small, moderately hard and shallow. There is some evidence that blooming is rare except in tem
perate zone lakes. Because of the ability to reproduce quickly, plank
ton may develop into a bloom within a few hours from a practically in
visible standing crop. Blooms usually consist of a single species.
Plankton plants and animals lead three types of existence. If color
less, such as animals, bacteria or other fungi, they may be holozoic (in
gest solid food) or saprophytic or saprozoic (absorb dissolved food, either organic or inorganic). If green, blue-green, brown, yellow, olive green, red or purple, they practically always contain chlorophyll and are holophytic in habit, capable of living on inorganic food. Among these lower plants and animals the exact nutritional requirements are very imperfectly known. We are also ignorant of the precise nature of many associations which occur too frequently to be without significance.
Such imperfect knowledge explains why plankton blooms have so long been a puzzle. It is unnecessary to cite the abundant literature dealing with it. Welch (1) sums up the matter by saying there is no single index of productivity for lakes, and Hutchinson (2) concluded that “ in general, clear-cut correlations between chemical conditions and the qualitative composition of the plankton are not to be expected. . . .”
Under these conditions, and with findings showing the cosmopolitan distribution of mici’oscopic plants and animals, it is easy to conclude that almost any large body of water contains all the necessary materials to support some of practically every plankton species. Therefoie, it may be expected that, if sufficient nutrient material be present, large growths will occur. The correctness of this is seen in the use of sewage fn Germany to fertilize fish ponds, in the enrichment of plankton for shell-fish by the use of commercial fertilizer (3), in the large plankton
796 SEWAGE WORKS JOURNAL July, 1945
increase reported by Juday (4) in Weber Lake, Wisconsin, following the application of soy bean and cotton seed meal, in the great increases of river plankton (5) below cities whose treated or untreated sewage enters the rivers.
Since the obnoxious blooms in the Madison lakes consist of chloro
phyll-containing plants it might be inferred that they are at least partly due to fertilization with N -K -P compounds, much as commercial ferti
lizer of this type is used for a successful cotton crop. Sawyer has shown in the first section of this paper that such fertilization is indeed a fact.
*Mendota... 264 15.20 39.7 145-180 0.06 0.36 0.01 0.03
*Wingra... 6 0.75 8.9 144-250 0.07 0.53 0.01 0.02
*Monona... 32 5.44 27.5 155-194 0.07 0.91 0.01 0.10
* Waubesa..., . . . 46 3.18 16.1 150-230 0.19 2.49 0.24 0.57
*Kegonsa... 71 4.91 15.1 150-236 0.07 2.03 0.16 0.35 Como... 9 1.45 6.5 178-261 0.09 0.19 0.01 0.01 Delavan... 35 2.83 26.2 126-182 0.06 0.87 0.01 0.07 Geneva... 36 8.76 64.7 118-182 0.05 0.14 0.01 0.01 Koshkonong... 2,533 14.80 — 119-292 0.12 1.32 0.01 0.06 La Belle... 14 1.77 10.8 168-203 0.07 0.26 0.01 0.01 Lauderdale (Mill)... 12 0.46 8.2 150-212 0.06 0.20 0.01 0.01 Nagawicka... 46 1.43 36.1 144-218 0.08 0.88 0.01 0.03 Nemahbin (Upper)... — 0.42 39.5 160-199 0.05 0.65 0.01 0.02 Oconomowoc... 3 1.27 29.8 161-196 0.04 0.15 0.01 0.01 Okauchee... 10 1.65 39.6 143-206 0.05 0.21 0.01 0.01 Pewaukee... 20 3.59 12.8 165-215 0.06 0.21 0.01 0.01 Rock... 11 1.91 20.0 1.51-182 0.07 0.11 0.01 0.01
* Madison, Wisconsin, lakes.
In v e s t ig a t io n a n d Fin d in g s
Five lakes at Madison and eleven in Southeastern Wisconsin were studied. Table 1 gives certain physical and chemical characteristics ior these lakes and for three rivers used for comparison. Koshkonong Lake is considered as a river for it is virtually an enlargement of the Rock River. All of them are of moderate hardness, all are small, and only Geneva exceeds 40 feet in mean depth. Mendota alone has a large drainage area. Only three of them, Monona, Waubesa and Kegonsa, receive large urban drainages, and these last two are the indirect, but quick recipients of urban drainage from Monona, the distance between the three being very short. The Madison lakes were studied inten
sively, but samples from the other lakes were taken once monthly, or less. Therefore, only six sets of samples from each lake are herein con
sidered. For the Crawfish River only three werq available. These were taken in April, May, July, August, October and November.
Chemical analyses at these times showed enough nitrogen and phos
phorus to support some plankton.
Figure 1 shows the number of plankton species present in each of species. Little if any significance can be attached to the number of spe
cies present, and it is highly probable that, if a larger number of samples had been examined, as many as 90 per cent of the species would have been found in each lake. The greater number for the rivers is largely due to the current; some species which in lakes would normally be found
011 the bottom are swept into suspension by the current in rivers, and appear in the samples. This is not invariably tru e; a few species seem to be characteristic of rivers, while a few lake species have not thus far been encountered in rivers. Due to the small number of samples con
sidered herein, it is easy to note certain species which occurred in only one of the lakes or rivers. This was true for the following groups:
Blue-green Algae... 4 species
798 SEWAGE WORKS JOURNAL July, 1945
A few of these may be termed rare organisms, but the greater part of them are common, and would eventually have been found in most if €> ' •> ^ not all of the waters under study. Some, however, are probably pe
culiar to the situation where found. Thus Diplostauron pentagonum has never been seen by the writer except in the waters of Monona, Waubesa and Kegonsa, although other workers have recorded it else
where. To summarize, however, the list of species is large and does not indicate marked differences between the several lakes examined.
The number of occurrences of single species and of all species was also recorded. Here too there are many factors to be considered.
Some organisms, for example, would not be found except according to
• well defined seasonal behavior. An example is the diatom Diatoma hiemale, which, as its name indicates, is a winter form. It was wide
spread in its occurrence, but was found only in the April samples, when the water was still cold. The Cryptophyceae are found at all seasons of the year, and they likewise were widespread; but whereas there were but 12 occurrences of Diatoma liiemale, Cryptomonas erosa occurred 100 times. With such behavior on the part of the various species, not too much dependence can be placed on the number of occurrences of a single species or a group of species. But unsuitable waters would tend to have less organisms, hence the chance of finding a species in a small sample would be less. There is also a succession; winter species die out, but new ones replace them. Figure 1 also shows the number of occurrences of all species in each lake or river; the rivers have the high
est numbers, and the three fertilized lakes, Monona, Waubesa and Ke
gonsa, are next. Actually the Crawfish River is lower than these three lakes, but it is to be recalled that only half as many samples were taken from it.
If fertilization is successful for all or certain species, then the num
bers of individuals for all or certain species should increase in Lakes Monona, Waubesa and Kegonsa. This constitutes the real test of the question. There are available four different checks on this statement, as follows:
(a) Total number of all organisms counted.
(b) Total volume of all organisms counted.
(c) The number of blooms occurring in the various situations.
(d) The comparative numbers of certain species.
The total number of all organisms will not alone suffice, because of the great divergence in size of various ones. Clirysococcus rufescens, for example, is a sphere 5 microns in diameter, while certain Strombidia may be thought of roughly as spheres 50 microns in diameter. The volume of the former would be about 65 cubic microns, of the latter about 65,000 cubic microns, or a thousand times greater. Even greater discrepancies occur in regard to the amounts of Microcystis aeruginosa which may be present. This organism forms irregular clumps which may vary from a mass of ten or twenty cells, each about 5 microns (2.5
Vol. 17, No. 4 PLANKTON PRODUCTIVITY. II 799 microns to 6.0 microns variation) in diameter, to masses three or four millimeters in diameter.
Figure 2 shows the total numbers of all plankton organisms counted.
Monona and Waubesa exceed all other lakes and rivers, although Kosh- konong (Rock River) virtually equals Waubesa. Kegonsa is lower, being exceeded by the river stations and by Wingra. However, in April there was a bloom of the diatom Fragitaría capuchina, a chain- forming type, in Kegonsa, and because of the numbers of this the sample was set aside to count this one species later. This sample was lost be
fore the count was ever made, but this single bíoom would have brought the total numbers in Kegonsa up to a considerably higher figure.
F ig u re 2.—The total number of organisms in samples examined from Wisconsin lakes and rivers. For each station, except the Crawfish River, 6 samples taken from April to November are represented.
The total volume of the organisms tabulated has not been fully worked out, as it. is a long and laborious process. Monona, T\ aubesa and Kegonsa seem to have more of the larger organisms than the other lakes: such large forms as the diatom Stephanodiscus astraea, the blue- green algae Anabaena spiroides and Microcystis aeruginosa, the Volvo- cale Pandorina morum, and the large olive green flagellate Crypto- in onas ovata were more abundant in the samples fi om these lakes than the others. Preliminary figures indicate for Monona a volume of about five times the highest figure for any other lake except Wingra. Wau
besa and Kegonsa seem to have about four times as great a volume of
800 SEWAGE WORKS JOURNAL July, 1945
plankton as any other lake except Wingra. These are rough figures, but will not be subject to much modification.
The third consideration, the number of blooms occurring in the lakes, is also difficult to evaluate critically. There is no definite crite
rion as to what actually constitutes a bloom, and it is easily possible for blooms to be missed when they last only a day or so. For purposes of this work, it was decided that, when an organism reached or exceeded 500 per ml. of raw water, it would be termed a bloom. For very small organisms, as Chlorella sp., this might not he noticeable in the water, but for organisms such as Ceratium hirundinella or Pandorina morum vivid discolorations of the w ater‘would be evident. Neither would blooms be noticeable to the layman if they did not produce some nui
sance. For the various lakes surveyed, some information was obtain
able as to blooming, by questioning individuals living adjacent to the lakes, and by determining whether copper sulphate treatment had been resorted to or not. According to this evidence blooming, if it occurred at all, in the lakes other than the Madison lakes, was negligible.
According to the samples examined, and using the figure 500 organ
isms per ml., the blooms noted in all the lakes were as follows:
Lake No. Blooms Constituent Genera
Como 1 Dinobryon
Delavan... 3 Chlamydomonas, Cryptomonas, Rhodomonas Geneva... 5 Fragilaria, Phormidium, Synedra
Nagawicka 1 Fragilaria
Nemahbin... 1 Fragilaria
Oconomowoc 1 Oscillatoria
Pewaukee... 2 Anabaena, Fragilaria
Wingra... 14 Ankistrodesmus, Aphanizomenon, Chlamydomonas, Cryptomonas, Dinobryon, Fragilaria, Gompho- sphaeria, Melosira, Microcystis
Monona... 10 Ankistrodesmus, Cryptomonas, Cyclotella, Dictyo-sphaerium, Fragilaria, Phormidium, Scenedesmus Waubesa... 19 Ankistrodesmus, Chlamydomonas, Cryptomonas, Cy
clotella, Fragilaria Melosira, Navicula Phormidium, Rhodomonas, Scenedesmus
Kegonsa... 12 Anabaena, Chlamydomonas, Cryptomonas Cyclothlla, Fragilaria, Melosira, Microcystis, Rhodomonas
This list is very instructive. Each of the three fertilized lakes showed a variety of organisms attaining high numbers in the course of the study, whereas the remaining lakes, except Wingra, did not re
motely approach these three. Six of them, including Mendota, did not have a single genus which showed 500 individuals per ml. in the samples examined, although in all of the samples from Mendota, which includes many more than those reported in this paper, there were four genera which attained or exceeded 500 per ml. 011 8 occasions. W ingra is somewhat of an enigma in its productiveness; there is 110 satisfactory accounting for it thus far.
In addition to the tendency noted above, it should be mentioned that Monona, Waubesa and Kegonsa each had a bloom of Microcystis aeru
Vol. 17, No. 4 PLANKTON PRODUCTIVITY. II 801
ginosa during the study. This is not shown, because the clumps of Microcystis were relatively few in number, but their large size more than compensated for counts below 500.
Finally, the evidence for high production in Monona, Waubesa and Kegonsa is found in the numbers of Cryptomonas erosa. This olive green flagellate is common, and occurred- in all of the lakes and rivers.
In addition it occurs during most of the year. It is found in clean water, but highly polluted waters are unfavorable to it. Present data indicate that its maximum occurrence is in the zone downstream from sewage treatment plants, where mineralization is practically complete, hut where some traces of organic matter may still be found and where there is a B.O.D. range between 1.0 and 4.0 parts per million. Table 2
T a b le 2.— N um bers o f Cryptom onas erosa in E a ch o f the L a k e s and R ive rs E xa m in e d
Lake or_ River CryptomonasCountTotal Per Cent Occurrence
Como... ... 898 100 Delavan... ... 1,788 100 Geneva... ... 351 100
La Belle... ... 370 100 Lauderdale... ... 528 83 Nagawicka... ... 161 100
Nemahbin... ... 156 100
Oconomowoc... ... 268 100 Okauchee... ...264 100 Pewaukee... ... 146 83 Rock... 384 67 Mendota... ... 251 100 Wingra... 1,696 100 Monona... 3,113 100 Waubesa... ... 4,852 100 Kegonsa... ... 3,266 100
Koshkonong (River)... ... 5,700 100 (7 samplings) Rock River... ... 928 100 (7 samplings) Crawfish River (3 samples)... 402 100 (3 samplings)
shows the numbers of this one species in all the samples taken. It is a suitable organism since its occurrence was 100 per cent in all but three of the lakes. The high numbers in Monona, Waubesa and Kegonsa indicate the fertility of these three lakes, there being almost two or three times as many of these flagellates in these three lakes as in Dela- van while Waubesa had about 33 times as many as Pewaukee. Since Monona, Waubesa and Kegonsa are the highest lakes as to inorganic nitrogen and inorganic phosphorus content, any comment seems unnec
essary. It might be noted, however, that Koshkonong and Delavan, also high in numbers of this flagellate, are correspondingly high in in
organic nitrogen and phosphorus. Wingra is a warning against pur
suing this reasoning too far, and indicates there are other factors which should be considered.
802 SEWAGE WORKS JOURNAL July, 1945 Su m m a r y
The facts cited tend to support certain general views, 1. All of the lakes contain about the same species of plankton algae and protozoa, hence all contain the minimal necessary fertilizing elements. 2. Even using samples as small as half a liter or less, the frequency of occur
rence of each species is great for each lake. 3. The actual numbers of all organisms in any lake is a poor criterion of production because of the great discrepancy of organism size. 4. The number of blooms, or of high peaks of production, for any or all species, appears to coincide with the amounts of plant nutrient material available. 5. Those lakes receiving the greatest amounts of nitrogen and phosphorus, and by inference other plant nutrients as well, tend to show the greatest total number of organisms', the largest number of blooms, the greatest vol
ume of animals and plants, and the greatest number of any particular species.
References
1. Welch, Paul S., “ Limnology.” McGraw-Hill Book Co. Inc., xiv + 475. New York. 1935.
2. Hutchinson, G. Evelyn, “ Limnological Studies in Connecticut. VII. A Critical Examina
tion of the Supposed Relationship between Phytoplankton Periodicity and Chemical Changes in Lake W aters.” E c o lo g y , 25, 1 (March 26, 1944).
3. Loosanoff, Victor L., and James H. Engle, “ Use of Complete Fertilizers in Cultivation of Micro-organisms.” Science, 95, 488 (1942).
4. Juday, Chancey, “ The Summer Standing Crop of Plants and Animals in Four Wisconsin Lakes.” Trans. W ise. A cad . Sci., A rts , L e tte rs, 34, 103 (1943).
5. Lackey, James B., “ Plankton Studies.” In: U. S. Public Health Bull. 276, 80-99, Govt.
Print. Office, Washington, D. C. (1941).