F URTHER LIMNOLOGICAL OBSERVATIONS ON THE
FINGER LAKES OF NEW: YORK 3:0 9:02 4, #4:
+ 2: +: By Edward A. Birge and Chancey Judy
From BULLETIN OF THE BUREAU OF FISHERIES, Vol. XXXVII, r9i9=20
2 yeument Now go5 Bars res) Shere aoe ek dashes lh Teowed Octoera, 1921
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http://www.archive.org/details/cu31924003012949
FURTHER LIMNOLOGICAL OBSERVATIONS ON THE
FINGER LAKES OF NEW YORK
: ; = @ 4 By Edward A. Birge and ee ce
From BULLETIN OF THE BUREAU..OF ‘FISHERIES, Vol. XXXVII, 1919-20
Document No. 905 : 3: 3 & fos os 3 2 : 2: : : : : Issued October8, 1921
PRICE, 10 CENTS
Sold only by the Superintendent of D: s, Gover t Printing Office, Washington, D.C.
WASHINGTON ;: +: -; >: : 3: GOVERNMENT PRINTING OFFICE : : : 0:0: 2 20: 9: 3 19%
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CONTENTS.
&
Page
THPOD UCI as eae dosha gastalati ea dr oink Seadoo ais aie e RR an erated vented racace. ol eeATensbaun amis audee AGES 21
Temperatures and heat budgets. ............ 0... c ccc c cence eee eee enn e eens easseree 2I1
Surface and bottom temperatures. ........... 0.0 cee c cece ee eee eens eontvavesatesdr Sioa 212
Thermal, regions i csccosd va wesaneney ans ye naadineead ae uleh witnesses 5g) spo Sitetuentgenaswaets sees 213
Summer’ heat incomesc: es vs.ccavueese ¥ernns ends oA eeaeNes Ss FR Lee Mat Ae Ehee a ees eaiacees 2r5
Distribution of heats scxce ce eacysdoeee ss gemseecacses eaOReRTOREN RUSS eae es ESSER sallosniste chavatans 218
Direct WOrkisaccsn queens Gos jcceras aad caced Ae Rateaaaieowhesg ke ENON Reeser 219
Distr tite dd: Works occ. oracise saciid 5 veosnal di cae, ddedidineduennngaty gctegonaeedalscond tie eS See SR a ea 221
SEIDEL ACEO Mi (CHEV ES ci sats icsce,crsishiexecien telesales Gacutransrc SedUipnmin ais deh child sadacResinees e oalucsnneanayane ETS 221
Heat and work as measured at depth...... 0b eee eee n enn ees 222
JADSOIptiOn OF SUIS CHET Y ioe tie sas easete een ciaraenstarese enacts Moma ie Ale tduncbe Becluili’s Sone aie e udherasnnena aly 223
Work: of thé: Sut (itt disttibiiting Neat. 05 csccscsvsnnd tings var ctvann ott atapyehtraal edn erk wae ahaha See 232
Ph ati tO 8s sey Gases iter seeagrevene irises ene enn Rai ad Wc ab Ms cucldca en eR RMR eeeKaenl gia Soy Gian dain Avera lgua Se 235
IMe th ods aise tieesacteeecre tenon sc ae enn fav citee er cxchit tacian teen cian Rau CeIn accnnen i 235
Net plankton’ cis :.ccnewoay cu gdaaiegaiadeanewan ide Segnn ia Gmaaweoenant cad weyeaeenese 236
Phytoplankton. :so.c00s cones utiareosaeees es igitiseGtan avenge anes bearaessxHEs 236
Zooplankton ycvss sus vacate vawgoraws canis o4 ve Reena wueMeae start MHMaERe Te RENE NET TOS 236
Nannoplankton vvececs sean ss esdavaneendeaeaesaes Gee Fouses ead ate OA eRe 24
Plankton Cables), jccsceudxndareveare ns Sst baits createed Ss souseran rapa hdyaieesa\ goku soe oid egusteentnadescatiserastigda teed 243
Botton: fatina 1c. 2ecusan sect Cee led aihce iS nua ceedt actin Sid auisudcnatios andnaitursatbdtdy A Davaysvtidud Wariharaeed oe 250
TAGS Hagbt tr CLC hs sy ache cans gies av sg pbs siamese a Geo chvc) ase eib ase cgeaed oh ecpac vara MeaumUR SAGES Meare Taare 252
210
FURTHER LIMNOLOGICAL OBSERVATIONS ON THE FINGER
LAKES OF NEW YORK.
ed
By EDWARD A. BIRGE and CHANCEY JUDAY,
Wisconsin Geological and Natural History Survey, Madison, Wis.
&
INTRODUCTION.
In 1910 and 1911 the U. S. Bureau of Fisheries enabled the authors of the present
paper to spend some weeks in the study of the Finger Lakes of New York. ‘The results
of this work were published in the Bulletin of this Bureau for 1912 (Birge and Juday,
1914). In this expedition there were applied to the study of the New York lakes
methods that had already been tried on the lakes of Wisconsin, which are much
smaller and shallower than those of New York. The resulting report dealt with the
hydrography of the lakes, their temperatures and heat budgets, their content of dis-
solved gases, and their net plankton. Since that study was made, the Wisconsin
survey has increased the scope of its observations on lakes. In particular there has
been devised and used extensively a new instrument, the pyrlimnometer, designed for
measuring the transmission of the sun’s radiation through the water of a lake; numer-
ous determinations of the weight of the individual members of the net plankton have
been made; an elaborate study of the nannoplankton, both numerical and quantitative,
has been completed; and it is now possible to make a rough correlation between count
and weight of both net plankton and nannoplankton.
The Bureau of Fisheries authorized a second expedition to the New Vork lakes
in July and August of 1918, in order to apply these newer methods to them. The
following paper reports the results of the observations.
The authors are indebted to Hobart College, Geneva, for the free use of its labora-
tories during their stay on the lakes, and to Prof. E. H. Eaton, of the same college, for
unwearied assistance in their work. Much of the success which was reached. was due
to this aid. All recorded series of temperatures between 1911 and 1918 were taken
by Prof, Eaton, as also were those taken after August 1, 1918.
This report comes from both of its authors, as was the case with their former paper
on the same subject. Mr. Juday, however, has prepared the part which deals with
the plankton and Mr. Birge that. which relates to temperatures and transmission of
radiation.
TEMPERATURES AND HEAT BUDGETS.
The temperatures of the Finger Lakes were discussed in our former paper (Birge and
Juday, 1914, pp.: 546-575), and it is untiecessary to repeat what was said there. Addi-
tional observations have been. made and the discussion can be enlarged, therefore, at
certain points..
aii
212 BULLETIN OF THE BUREAU OF FISHERIES.
Table 1 shows the dates at which series of temperatures have been taken for usein
computing the summer heat income. A five-year mean of August temperatures may be
obtained for Canandaigua and Cayuga Lakes and a four-year mean for Seneca Lake.
Additional observations are not likely to make essential changes in the results thus
obtained.
SURFACE AND BOTTOM TEMPERATURES.
Observations of the surface in August and early September show in Canandaigua
Lake a mean of 21.4° C., ranging from 20.7 to 21.7°; in Cayuga Lake the mean is 21.1°,
ranging from 19.8 to 22.6°; in Seneca Lake, 20.4°, ranging from 20.0 to 21.1°- These
must not be taken as the maximum surface temperatures, which undoubtedly are likely
to come earlier in the season. Seneca Lake was visited on July 24, 1918, in the after-
noon of a clear, hot day and at the close of a hot and windless period. The surface
temperature in water 40 m. deep was 25.0° C. A heavy shower with violent squalls
occurred later in the afternoon. The surface temperature on July 25 was 20.8° and
there was a marked rise of temperature above that of the 24th at all depths between
5 and 30 m.
TABLE 1.—DaTES OF TEMPERATURE SERIES: SURFACE, BOTTOM, AND MEAN TEMPERATURES.
Lake and date. Surface. | Bottom. | Mean. Lake and date. Surface. | Bottom. | Mean.
CANANDAIGUA LAKE. CAYUGA LAKE—continued.
"€. °C. °¢. 9C: be 2 °C,
Aug. 20, r910 21.7 5.4 1x05 |] AUG. 16, IOT7. oe cece eee e eres 22.6 43 9. 44
Sept. 4, r91r..... wad 20.7 43 10.02 |} AUg. 30, IQT8.... eee eee ee eee 22.0 4.2 9. 66
Aug. 27, 1914. . siete 21.6 45 10. 11
Aug. 31, 1916. . 21.6 5.0" 1x. 57 | Bi (0s eee 25.1 4.2 9. 43
July 27, 1918. . wile 23.1 5 1x.9r |}.
Sept: 3; 1918.55 seca seneserseves 21.5 5.0 II. 42 SENECA LAKE.
Meat} 205.058 desguteenes 21.4 48 10.95 |} AUG. 3, IQTO.... ee eee eee ee aes 20.2 4.2 7.91
Sept: 2) TOLTssiisciceeate os deeuig 20.0 4.0 7.34
CAYUGA LAKE. Sete. Fp: TQ a iescicisieieiniwions cia ose stare 2I.I 4.0 8.27
AUg. 29, 1918... ..-.. cece ee eee 20. 8 4.0 8.07
gue EK, EQUOvecsaivenicmaniovaernes 19.8 43 9. 24
ER, TOME: sos iaasadavsraraiaverae 20.0 4-1 8.93 Meaticccsncdedreteiss weneaies 20. °!
Sept. 4, 1914........00ee eee ee ee 21.4 4 9. 65 4 Se us
Bottom temperatures average 4.8° C. in Canandaigua Lake (84 m. deep), ranging from
4.3 to 5.4°; in Cayuga Lake (133 m.) they average 4.2° with a range from 4.1 to 4.3°; in
Seneca Lake (188 m.) the mean is 4.05° and the range from 4.0 to 4.2°. The reading was
4.0° in three of the four series.
In most of these cases the observations were made with a Negretti and Zambra deep-
sea thermometer divided to 0.5°. Such an instrument gives approximate but not very
exact results. In 1918 the attempt was made to ascertain whether the water of Seneca
Lake might not be below 4.0° C. at the bottom. The temperature of maximum density
is lowered by pressure, as pointed out by Hamberg (1911, pp. 306-312). Since the
depth of Seneca Lake is 188 m. the pressure at the bottom is about 19 atmospheres, and
maximum density would be reached between 3.3 and 3.4°.
A special thermometer was used, ranging from — 2.0 to + 14.0° and divided to 0.1°.
This instrument read exactly 4.1° when at the temperature of the surface water, 19.3°.
Correction for the expansion of the mercury. shows that the true temperature at the
bottom was 3.88° and, therefore, below 4.0°, though decidedly above the temperature
FINGER LAKES OF NEW YORK. 213
of maximum density for the depth. Hamberg (loc. cit.) quotes examples of similar
temperatures from Lakes Ladoga and Mjésen. It is worth noting that the temperature
in both these lakes at the depth of 190 m. was between 3.8 and 3.9°. The observations of
Huitfeld-Kaas (1905, p. 4) in Mjésen give temperatures at 200 m. which rise as high as
4.1° in November and as low as 3.65 or 3.75° in April and May. At the bottom, 400
m. or more, 3.60 and 3.75° were oa: 6 20-
found. At this depth the tempera- ° i
ture of maximum density is slightly ™ oe
i
J
q
above 3.3°. [
It is very probable that the J
temperature of Seneca Lake, record-
ed in 1910 as 4.2°, was really close to J
4.0°, and that all readings of 4.0° at i
$
Vv
the bottom indicate temperatures as ,,
low as 3.8 or 3.9°. It is not worth
while, however, to apply an estimated . 7 H
correction to these readings. There Lv: ¢ rf
is no reason to believe that the bot- y i 7
tom temperature of Cayuga Lake is / at”
below 4.0° in late summer. J A f
THERMAL REGIONS. a A _s
i
Table 2 shows the thermal / Hf
regions of the several lakes. The al
epilimnion of Canandaigua Lake was
11 or 12 m. thick; the thermocline VA
was 4 to 8 m. thick, averaging 6 m. | i
In Cayuga Lake the epilimnion was
13 to 15 m. thick and the thermocline
4 to 5 m. thick.
There was more variation in |
Seneca Lake. The epilimnion was |
15 to 19 m. thick and the thermocline
4to6m. On August 1, 1918, the
epilimnion at Hector Point was only
rom. thick; on August 29, at Kashong, it was determined at 20 m. But since Kashong
is near the north end of the lake and the readings were taken on the day following a hard
south wind, the epilimnion was no doubt thicker there than observations at the center of
the lake would have shown. In computing gains of heat, therefore, the thickness of
the epilimnion for 1918 was taken as 15 m.
On July 24, 1918, at the north end of the lake in 40 m. of water the epilimnion was
only 7 m. thick. This was at the end of nine days of hot and calm weather and is an
exceptional condition. ‘The thickness of the epilimnion rapidly increased to 14 or 15 m.
in the course of the following week and was subject to considerable fluctuations.
so
Fic. 1.—Curves of mean temperature to 34m.depth. A, Canandaigua
Lake; B, Cayuga Lake; C,Seneca Lake. (See Tabie x, p. 212.)
214 BULLETIN OF THE BUREAU OF FISHERIES.
TABLE 2.—DISTRIBUTION OF SUMMER Heat INCOME TO THERMAL REGIONS OF LAKES.
[Nore.—Mean is derived irom mean temperatures. Extent=vertical thickness of region in meters; R. ‘T.=reduced thickness
of region, i. e., the thickness in meters of the region when reduced to the area of the surface of the lake. It is computed by
dividing the volume of the stratum expressed in meters by the area of the surface of the lake expressed in square meters;
T=gain of heat above 4.0°, i. e., the summer heat income expressed in degrees centigrade; Cal.=gram calories per square
centimeter of lake surface; P, ct.=per cent.] ‘
CANANDAIGUA LAKE.
1910 ‘ I9Ir
Thermal region.
Extent. | R. T. Ty Cal, P. ct. Extent. | R. T. aT, Cal. P. ct.
o-12 10.0 16.8 16, 800 61.8 o-12 10.0 15.5 15, 500 66. 4
12-20 5.6 9.3 5, 200 19.1 12-20 5.6 9.2 5, 200 22.0
20-84 23.1 2.73 5, 200 19.1 20-84 23.1 1.04 2, 400 11.6
Meanortotal....].......... 38.7 7.07 Fy BOO | sccreusiecase’s Sallie Pes aneeces 38.7 5.99 23, 200 |e. eereenee
194 1916
Thermal region.
Extent. R. T. Tv. Cal, P.ct. | Extent. R. T. T Cal. P. ct.
Epilimnion.... O-Ir 9. 34 aI.o 15, 830 58.6 o-12 10.8 aI.2 17, 420 59.3
Thermocline. 11-18 5. OL 14.0 5, O10 18.6 12-20 5.64 13.3 5, 270 17.9
Hypolimnion.. 18-84 24. 45 6.5 6, 160 22.8 20-84 23. 08 6.9 6, 680 22.7
Meanortotal....].......... 38. 8 10. 96 27,000 |.ccesecersfesesves pis 39. 52 IX. 57 995370: |asisee ea vee
1918 Mean.
Thermal region.
R. T. T. Cal, P.ct. | Extent.| R. T. ne Cal, P. ct.
* 9.34 20.7 15,610 54-3 O-Ir 9. 34 20.8 15, 660 58.0
2.91 16.4 3, 560 12.4 II-17 7.18 15.9 4,970 18.4
26. 25 7 9, 600 33-3 17-84 25. 82 16.5 6, 350 23.6
38.5 Il. 42 BO AAO) | deciaysispajagaca.c aches iis as praia 42. 34- 10.95 26, 980 |........08
CAYUGA LAKE.
1910 IQIr
Thermal region.
Extent R. T. T Cal. P.ct. | Extent. R. T. T. Cal. P. ct.
Epilimnion.. ois 11.8 18.5 18, 300 64. 2 o-16 12 15.2 19, 000
Thermocline. . ves) 19722 4.62 10. 3 4, 800 16.9 16-21 3-3 ; a a 300 a 4
Hypolimnion.......... 22-133 38.3 I. 41 5,400 ' 18.9 21-133 38.7 r.14 4, 400 16.5
Meanortotal....].......... 54-72 5. 26 BB) S00: | sisiarhase airs shales doers 54.5 4-94 26, 700 |........05
, I9l4 I9l7
Thermal region. ;
Extent. | R. T. T. Cal. P.ct. | Extent. | R. T. T. Cal. P. ct.
o-Is II.97 21.2 20, 624 66. 8 O-13 10, 56 21.0 17, 60.
15-20 3.35 16.7 4, 266 13.8 13-17 2.76 15.6 3» oe ro. i
20-133 39. 27 5.5 5,980 19. 4 17-133 14. 29 6.1 8, 542 28. &
Meanortotal....J.......... 54-59 9. 65 BO; BIO: Pare seers nile avesevaroronre’s 0 27.61 9.44 29,720 |... eee seas
1918 Mean.
Thermal region.
R.T. T. Cal. P.ct | Extent.| R.T. T. Cal, P. ct.
Il.97 20.4 19, 734 63.9 o-I5 11.9 20. » 538
270) mo | ao} 88] x20 | “s3s| tea | ‘geas| a
39. 94 6.1 8, 460 27.3 20-133 39. 27 5.6 6, 309 2a
Meanortotal....].......... 54. 61 9. 66 39, 910 |..... indies a 54. 59 9. 40 29, 480 |......
FINGER LAKES OF NEW YORK. 215
TABLE 2.—DISTRIBUTION OF SUMMER Heat INCOME To THERMAL REGIONS oF LakES—Continued.
SENECA LAKE.
' ee be T910 IQII
Thermal region.
Extent. | R. T. T. Cal, P.ct. | Extent. | R.T. T. Cal. Pct.
o-12 Ing 15.4 17, 700 53.8 ors 13.8 15.4 21, 200 7. 5
u I 12-20 6.2 10.2 6, 400 19.5 15-22 6.0 8.6 5, 200 17.5
Hypolimnion... 20-188 70.9 I. 21 8, 800 ar.7 22-188 68. 8, 0. 47 3 300 11.0
Meanortotal....].......... 88.6 372 325.900) ll isoag vertices aeacismacarers 88.6 3-35 29,700 |oc...eee ae
wr 1914 1918
Thermal region. ae y
. Extent. | R.T. Tv. Cal. Pct. | Extent.| RT. T. Cal, P. ct.
o-I9 16. 92 20.0 27, 000 971.2 o-rs 13. 60 20.0 22, 420 62.2
19-25 4. 83 13.9 4, 780 12.6 I§s-19 3.32 14.6 3,510 9.8
25-188 » 66. 85 49 6, 090 16.2 19-188 71. 68 54 10, 030 27.9
Mean or total..../.........- 88.6 8.27 B37 870: | ccisteda ca ada te axe 88.6 8.07| 36,060 ]..........
Mean.
Thermal region.
Extent. RT. T. Cal. P. ct.
Dili rninn lone ciscisis tes winiuiatnwreines ns vovieedaislaigavents a bales dardsqaislars bo dda Saeceaanvamanes ees ois 13. 60 19.8 2%, 410 63.0
Thermocline is scissiciseeiivians oe sglaneararnas tg a Aeldieeelat ede eet doo nagunamas 93 2 Y 15-20 4.13 14.8 4,450 13.1
PEYPOUMIIION, socsi ria nemnewss ya eesoaseeecs rien past mlneiaeg ee senateaarsiade ns he sta 20-188 70. 87 5.2 8, 160 24.0
Mean or totals crseuavas careeeuss ve aeuesanss veeenneas taunmeuse vaalnnnas § ee 88.6 $84 | 34,890 [rrcowerves
SUMMER HEAT INCOME.
The summer heat income represents the gains in heat of the water of the lake
above the temperature of 4°. This notion was put forward in our paper on the New
York Lakes (Birge and Juday, 1914, p. 562) under the name of “ wind-distributed
heat.” In the following year (1915, p. 167) I proposed the name ‘‘summer heat in-
come’’ for the same gains of heat, preferring a term which does not imply any theory
as to the method of distributing such heat. For reasons discussed in the same paper
(1915, p. 186) the summer heat income of lakes can be used as an index of their heat
exchanges in much the same way as the annual heat budget. The heat income, like
the heat budget, is stated in gram calories per square centimeter of lake surface. For
the sake of brevity it is ordinarily stated as so many calories without adding in every
case the qualifying terms. The whole question of heat budgets and the methods of
computing them is discussed in the paper already referred to (Birge, 1915).
Table 2 shows the summer heat income of the three lakes concerned. Canandaigua
Lake shows a mean income of nearly 27,000 cal./cm.’, ranging from 23,000 to more
than 29,000 cal. Cayuga Lake has an income of about 29,500 cal., ranging from less
than 27,000 to nearly 31,000 cal. The income of Seneca Lake is about 34,000 cal.,
ranging from less than 30,000 to nearly 38,000 cal. The smaller income of Canandaigua
Lake is mainly due to the thinner epilimnion, which, in turn, is due to the smaller size
of the lake and to the protection from wind afforded by its high shores. So far as
area goes, Cayuga Lake is as well off as Seneca and its depth is ample to secure as large
anincome. But while the epilimnion in both lakes is 15 m. thick, its reduced thickness
is nearly 12 per cent less in Cayuga Lake than in Seneca. ‘This fact is due to the large
extent of shallow water at the north end of the lake, which causes a corresponding reduc-
216 BULLETIN OF THE BUREAU OF FISHERIES.
tion in the amount of heat as stated in terms of units of surface area. The upper 20
m. of these lakes contains 75 to 80 per cent of the total quantity of heat, and the reduced
thickness of this stratum in Cayuga Lake is nearly 14 per cent less than in Seneca Lake.
(See Table 3.) The slightly higher temperature of the stratum in Cayuga Lake is not great
enough to compensate for this difference in thickness (cf. Birge and Juday, 1914, p. 574).
A longer series of years would undoubtedly change the figures stated above. But
it is not probable that such a series would greatly alter them or that it would change
the general relations of the heat income of the several lakes to each other. The smaller
lake has the smaller income, largely because of its thinner epilimnion. Cayuga Lake
has less heat than Seneca, largely because of the smaller ratio between maximum and
mean depth. ‘The differences are not so great but that the series of budgets overlap,
the largest heat income of Canandaigua being larger than the smallest of Cayuga, and
Cayuga’s series overlapping in a similar way that of Seneca. The largest heat income
in the series is that of Seneca in 1914, nearly 38,000 cal.
Table 2 also shows the distribution of heat to the three thermal regions of the
lakes. ‘The epilimnion contains about 60 per cent of the summer heat income, ranging
from 53 to more than 70 per cent. ‘This stratum, together with its thermal depend-
ency, the thermocline, contains from 70 to nearly go per cent of the heat. Thus in Seneca
Lake, which may be nearly 200 m. deep, a surface stratum occupying little more than
the upper one-tenth of the depth contains from three-fourths to nine-tenths of the heat
accumulated from the sun during the season.
Table 3 shows the distribution of the summer heat income by 10 m. intervals.
It shows the same facts as Table 2 but in another form. It makes especially clear the
small amount of heat which can be carried to considerable depths. In Canandaigua
Lake, for example, the total quantity of heat transmitted below 50 m. during the season
does not exceed the quantity delivered to the surface in one summer day; and even in
the much larger and deeper Seneca Lake it does not exceed two days’ supply.
TABLE 3.—DISTRIBUTION OF TEMPERATURES AND OF CALORIES OF SUMMER HeEaT INCOME.
[NotE.—R. T.=reduced thickness of stratum in meters; T.= temperature in degrees centigrade; Cal. =calories of summer heat
income, i. e., gain of heat above 4°; P. ct.=per cent of heat income in stratum.]
CANANDAIGUA LAKE.
. I9Io Igir I9I4
Depth in meters. R. T.
as Cal. P. ct. T. Cal. P. ct. T Cal. P. ct
8. 56 21.2 14,720 53-3 19.9 13, 610 58.2 21.r 14,640 56.3
7.16 14.3 7,370 27.0 14.2 7, 300 31.5 13.6 , 870 26. 4
6. 43 24 2,190 8.0 6.1 I, 350 5.6 2A 2, 190 8.4
5-71 6.2 1, 260 47 49 510 2.4 6.3 I, 310 5.0
4. 88 5.8 880 3-3 4.6 290 2 5:4 6! 2.6
3. 65 5.6 580 2.3 45 180 8 4.8 290 LI
I. 90 55 280 I 4.35 70 3 46 110 +4
+53 5.4 70 3 43 2O [a ncncnccee 45 20 oe 4
bie since sates II. 05 27,350 100.0 10, 02 23, 330 100. 0 10. 71 26, 110 100, 3
1916 1918 Mean.
Depth in meters. R. T.
T; Cal. P. ct. T. Cal. P. ct. x, Cal. P. ct.
O10. ee eacesmiees 14 ie 8. 56 21.4 14, 890 50. 7 20.8 14, 380 50.0 20,
. 9 14, 450 rt
FOK8O eects csnhine erin exe 7.16 14.9 7, 800 26.6 14.9 7, 800 27.1 14.4 a he a 2
ec 6. 43 8.6 3,420 11.6 8.9 3,150 Ilo 7.8 2, 460 9.1
5-71 6.6 1, 480 5.0 6.8 1, 600 5.6 6.1 I, 230 46
4 88 5.9 930 3.2 5.9 939 3.2 as 740 2.7
3. 65 SS | 550 19 5.6 570 2.0 5.2 430 16
1.90 5.3 250 8 5.4 270 one) 5.1 200 4
+53 5.0 _§0 +2 5.3 70 +2 4 40 a
isle Reinte ne IL. 57 29, 370 100, 0 II. 42 28,770 100. 1 10. 95 26, 980 99. 9
FINGER LAKES OF NEW YORK. F 217
TABLE 3.—DISTRIBUTION OF TEMPERATURES AND OF CALORIES OF SUMMER HEAT INcomE—Con.
CAYUGA LAKE.
‘ 1910 we IQII 914
Depth in meters. R. T.
Fr T. Cal. P. ct. sb Cal. P. ct. T. Cal. P. ct.
8. 42 19. 2 12, 800 44.8 19.9 13, 400 40. 8 21.3 14, 600 47-3
6. 88 | 17.7 9, 400 32.9 17.1 9, 000 33-5 18,8. I0, 200 33-0
6.27 8.8 3, 000 10.5 8.2 2,600 9.7 9.6 3, 500 11.3
5-79 6.4 1,400 49 5.6 900 34 6.2 I, 300 4a
5.12 5.4 7oo 24 47 350 1.3 5.2 600 1.9
4 52 49 400 1.4 44 180 +7 4.6 290 “9
4.93 4.6 250 “9 44 140 “5 44 160 +5
3-60 45 190 +6 43 130 +S 43 ro) +3
5. 89 45 290 1.0 4.2 120 4 4-1 go 3
4.09 44 170 a) 42 80 3 41 4° ope
54. Or 9. 24 28,600 |.......... 8.93 26, QO! Pesos cetneies, 9. 65 30, 870 ai
e I9I7 1918 Mean.
Depth in meters. R. T.
T Cal. P. ct. T. Cal. P. ct. T Cal P. ct.
8. 42 21.3 _ 14, 600 49.2 aur 14, 400 46. 6 20.6 14,000 ALS
6. 88 16.1 8, 300 28.0 16.4 8, 500 27.5 17.3 9, 100 31.0
6.27 8.8 3, 000 10.1 9-1 3, 200 10. 4 9.0 3, 100 10. §
5.79 6.9 I, 700 57 toes 1, 800 5.8 6.4 I, 400 48
5.12 5-7 880 3.0 6.3 I, 200 3-9 5.5 77° 2.6
4 52 49 410 u4 57 759 24 49 410 14
4.03 48 320 Li 5r 44° L4 46 260 9
3: 60 4s 180 6 47 250 8 45 160 5
5. 89 4a 210 “7 45 290 x) 43 190 “7
4.09 43 120 4 42 80 <3 42 go <3
* 54. 61 9. 44 29,720 |.......... g. 66 30, 910: | ii vanteces 9. 40 29, 480 |.....006 se
SENECA LAKE.
ae I9I0 I9IL 1914
Depth in meters: R. T.
T. CaL P. ct. T Cal. P. ct. T Cal P. ct.
9. 35 19. 6 14, 600 444 19.6 14, 600 49. 5 20.3 15, 200 40.1
8. 40 15.7 9, 600 29. 2 16, 2 10, 200 34-5 19.2 12, 800 33-8
7. 86 8.7 7.3 2,600 8.8 Il. 4 5, 800 15.3
7.41 6.4 5.8 800 2.7 7.1 2, 300 6.1
6. 92 5.5 4.6 400 13 5.4 970 2.6
6.49 49 44 280 I.0 47 450 a
5. 89 4.8 43 160 6 44 240 6
5. 52 4.6 43 160 -6 42 110 “3
g. 82 AS 4.2 ates fs
12.14 42 41
5. 76 4.2 4.0
3. 22: 42 40
eta Sarise 77% 82,900 |..1....... 7.34 29,600 |......:... 8.27 BI BIO Ns ie. areslaises
1918 Mean.
Depth in meters. R. T.
ae Cal. P. ct. T. Cal P. ct.
9.35 20.5 5,400 42.7 19.9 14,900 43.8
8. 40 17.2 II, 100 30.8 17.1 10, 960 32.4
7. 86 9-9 4, 600 12.7 9.3 4, 200 12.4
74 6.8 2, 100 5.8 6.3 I, 700 5.0
6. 92 6.0 I, 400 39 5.4 940 2.8
6. 49 5.2 760 2.0 46 420 12
5. 89 44 230 16 45 270 8
5.52 43 160 +4 4.3 180 7S
9. 82 4.2 190 8 4.2 260 8
12.14 4.1 120 +3 41 130 «4
5. 76 ar 4.0 40 eS
3.22 4.0 BO iasce's s avorinn
sige we 7.84 34,020 |.......85
46104°—21——-2
218 BULLETIN OF THE BUREAU OF FISHERIES.
DISTRIBUTION OF HEAT.
The radiation from the sun which enters a lake is rapidly absorbed by the strata of
water near the surface. Even in very clear lakes only 20 per cent of the total radiation
passes the 1-meter level, and only about ro per cent passes the 3-meter level. (See p.
228.) All of the warming of the deeper water and most of the warming of that which
lies below the surface meter is due not to insolation but to mixture of warmer water
carried down from near the surface. This mixture of warm surface water with the
cooler water below is effected by the wind for all temperatures above 4°. It involves
work against gravity, since the warmer water is lighter than the cooler. This work may
be measured and may be conveniently stated in gram-centimeters per square centimeter
of lake area. These facts were stated in our paper on the New York Lakes (Birge and
Juday, 1914, p. 562). The principles underlying these ideas were later published as a
special paper (Birge, 1916, pp. 341-391) and were applied to Lake Mendota. It was
there shown that about 1,210 gram-centimeters of work per square centimeter of area
are needed to distribute 18,400 gram-calories of heat per square centimeter of area
through the waters of a lake 24 meters in maximum depth and 12.1 meters in mean depth.
It is understood that in this statement the term “‘work’”’ is not used in an exact sense;
since in it are included both the action of the wind in distributing heat, which is properly
work; and also the direct effect of insolation, which does not involve work. (See Birge
and Juday, 1914, p. 574; Birge, 1916, p. 360.) This division of the distribution of heat
between sun and wind is discussed later in the paper. For the present, however, the
matter is discussed as though the entire distribution of heat were due to wind.
TABLE 4.—TEMPERATURE (T) IN DEGREES CENTIGRADE AND GRAM CENTIMETERS (G. CM.) oF WorK
NECESSARY To DISTRIBUTE THE SUMMER HEAT INCOME.
[Nore.—This table shows the “direct curve of work,” i. e., the work necessary to carry the warmed water from the surface to
the stratum in question. It is stated in gram centimeters per square centimeter of surface of the lake.]
CANANDAIGUA LAKE.
Igto IQII 91g 1916 1918 Mean.
Depth in meters.
T. G. cm. ey G. cm. r G. cm. Ts G. em. T. G. cm. T. G, em.
236. 2 20.0 224.0 215 240. 8 2u.5 240. 8 aur 224.0 2I.1 224.0
582.0] 19.6 505.3 20.7 574.1 21.3 613.0] 20.6 568. 1 20.6 568. 1
630.7] 17.5 589. 5 16.9 539-3 17.8 612.4] 17.0 548.4] 17.5 589. 5
199. I 10. 6 199. I 10. 2 176. 6 12,0 288. 3 12.5 309.6 | 11.2 235.5
100. 4 6.2 25.8 74 62.7 9.2 149. 8 . 8 191.9 8.2 100. 4
60. 8 5.4 13.7 6.9 56.5 8.0 106. 1 8.0 106. 1 Rt 64.2
75.2 49 13.9 6.3 83. 2 6.6 104.9 6.8 122.8 6.1 69.3
57.2 4.6 6.6 54 35-2 5.9 63.8 5.9 63.8 5-5] 39.6
42.0 45 4.0 4.8 10.0 5.5 36.0 5.6 42.0 5.2 24.0
22.3 44 I.2 4.6 37 5.3 17-4 54 19.8 5.1 12.4
6.7) 4.5 +4 45 18 5.0 3-3 5-3 5.8 4.9 2.9
Vievaee 2,022.6 |.......] 1,583.5 |...-...] 1,782.9 ].......] 2,235.8 |.......| 2,202.3 |....... 1,929.9
FINGER LAKES OF NEW YORK. 219
TABLE 4.—TEMPERATURE (T) IN DEGREES CENTIGRADE AND GRAM CENTIMETERS (G. Cm.) oF WoRK
NEcESSARY TO DISTRIBUTE THE SUMMER Heat INcomE—Continued.
CAYUGA LAKE.
IgIo Igir 194 IQI7 1918 Mean.
Depth in meters.
oh G. om. E. G. cm. 3 G. cm. T. G. cm. t. G. cm. T. G. cm.
19. 6 187.6 | 20.0 195.4) 21.4 229.8] 21.8 239.8) 214 237.5 20. 8 ams.3
19.6 488. 4 19.9 497.1 21.4 598. 2 20.7 554.9 | 20.8 560.7} 20. 540. 4
19.4 727,6| 19.6 745-3 | 209 864.4 | 18.8 674.7) 19.3 718.8 | 19.6 745-3
16.0 603.6 | 14.9 503.4 16.7 673.9 13.2 363.9 13.4 379.1 14.8 494.6
9.9 189. 6 9.0 137-9 | 11.0 264. 2 9.8 183.8 | 10.0 | 196. 1 9.9 89.6
7.8 95.0 6.9 56.0 8.0 105. 2 4 9°. 7 8.2 115.3 7 90. 7
6.4 94.9 5.6 30.3 6.2 70.7 6.9 133-3 7.1 147-5 6.4 92.9
5.4 41.6 47 5.8 5.2 20.8 5:9 53.1 6.3 97.0 5.5 41.6
49 17.4 4.4 5.0 4.6 6.2 4.9 17-4 5-7 54.8 49 17-4
4.6 9.2 44 2.6 4.4 2.6 4.8 13.1 5.1 26. 2 4.6 9.2
4:5 5:4 4.3 2.7 4.3 2.7 4.5 5.4 4.7 12.1 45 4.0
4.5 10.6 BoD hase saad Beh, | oa de Seka es 44 5.3 4.5 10.6 4-3 53
44 72 Bie Wh sats Savdind Bk. esheets 4:3 4.8 Aza lies oe anceeas Boga || ern weyeies
as Rianie 2,478.10 |.......] 2,181.5 |.....-6| 2,838.7 [o....0e] 2,340.2 |... ee] 255527 [eee e ee 2, 446. 3
SENECA LAKE.
1910 IQIr 1914 1918 Mean.
Depth in meters,
T. G. cm. a G. cm T. G. cm. T G. cm ye G. em
OB senna sa Amaia days vi 19. 8 205.9 19.7 203.5 20.4 220, 2 20.6 20. I
5-I0..... 19. 4 552.8 19.2 539-4 20. 2 603. 0 20.5 19.8
IO-IS..... 17.8 718, 2 17.8 718. 2 20, I 959. 4 20. 2 19. 2
15-20..... 13.3 457-8 14.0 526.3 18.0 996. 4 14.0 14.8
20-25..... 9.3 . 80 112.2 13.4 585. 5 IL. 5 10.6
25-30..... 7.9 6.3 44.9 9.4 237-5 8.2 8.0
3O-40.,... 6.4 5.8 67.6 qt 195.0 6.8 6.3
40-50..... 5.5 4.6 9.3 5-4 49.8 6.0 5:4
50-60..... 49 44 3.5 4:7 14.0 5.2 4.6
60-70..... 4.8 434, 3-8 44 3.8 44 4.5
7o-80..... 4-6 43 5.5 Be 2 Vocsuvswietesa oe 4.3 4.3
80-100 45 Be 2 lecegeinasas BO betestrguss eae 4.2 4.2
T00-130.... 4.2 ALD leienieentes AO: lesions sans 4.1 |. 4-1].
130-150... 4.2}. As O leases AiO! |eexsaeycezis 40]. 4.0].
150-188 4.2 AEG: |icicctass ony 450 basse ca. es 4.0 4.0
errs ener) STO. |. ovemandes 2,234.2 |occeseeeee| 3,864.6 |.......006 Bere rere irs
DIRECT WORK.
Table 4 shows the distribution of heat for the lakes under consideration. The
resuits of the computation only are given; the details of the method being quite similar
to those illustrated in the paper before referred to (Birge, 1916) and also in Table 5,
page 220, of this paper. Taking the means only it appears that in Canandaigua Lake
about 1,930 g. cm. of work per square centimeter of the area of the lake are needed to.
distribute about 27,000 cal. of heat through the water, the depth of which is 84m. In
Cayuga Lake about 2,450 g. cm. of work distribute 29,500 cal. in water, the maximum
depth of which is 133 m.; in Seneca Lake 2,880 g. cm. distribute 34,000 cal. in water
the maximum depth of which is 188 m.
The amount of work needed to carry the heat to the corresponding stratum of the
several lakes varies with the loss of density of the water due to rise of temperature
and with the quantity of water in the stratum. The latter factor is represented by
the reduced thickness of the stratum. (See Table 3.) The first factor is the more
220 BULLETIN OF THE BUREAU OF FISHERIES.
variable in these lakes, and to it are due most of the striking differences in the work
required to warm the deeper strata: In the 30 to 4o m. stratum of Canandaigua Lake,
for instance, it required about 70 g. cm. to put 1,230 cal. into place. In the corre-
sponding stratum of Cayuga Lake it required 93 g. cm. to place 1,400 cal. The
difference in calories is about 14 per cent, in work over 30 per cent. This is mainly
due to the difference in loss of density. At 6.1°, the temperature of Canandaigua Lake,
this is 35 points,! and at 6.4°, the temperature of Cayuga Lake, it is 46 points, or over
30 per cent greater.
Table 4 shows that a great amount of work is necessary to produce by mixture
the high temperature of the upper strata; it shows also that an almost incredibly small
amount of work is needed to carry considerable heat to great depths if only it involves
but little rise of temperature. Note, for example, Seneca Lake, where 42 cal./cm.?
of surface are transported to a mean depth of 55 m. for an expenditure of about 1 g. cm.
On the other hand, in the corresponding stratum of Canandaigua Lake, each gram
centimeter of work transports only about 18 cal. The difference is due to the much
greater rise of temperature in the smaller lake—reaching 5.2° instead of 4.5° in Seneca
Lake.
TABLE 5.—DETAIL FoR SENECA LAKE OF THE Facts oF DisTRIBUTION oF MEAN SUMMER Heart INCOME.
{Norg.—T.=temperature in degrees centigrade; 1-D=loss of density due to warming; RTXZ=factor, reduced thickness
multiplied by depth. Direct=work done in behalf of stratum in question; Dist.=work done im stratum in question; Cal.=
calories of summer heat income in stratum. All expressed in units per square centimeter of lake surface. See fig. 3, p.
229; also Birge, 1916, p. 349,355.) .
Direct work.
Depth in meters. T. =D. |RTXZ. Cal. in G.cm. | Cal.
0. 001853 1,624 ©} 2,874.4} 34,020
181g 1, 588 1] 2,589.8 } 32,396
1815 1,555 2 | 2,323-3 | 30,808
1790 I, 530 3 | 2,074.5 | 29,253
1770 1, 504 4] 1,843.0] 27, 723
1770 1, 488 5 | 1,629.4] 26,219
1749 1,447 6 | 1432-4 | 24,73
1729 1,422 7 | 1,251.6 23, 284
1708 1,382 8 | 1,086.7 21, 862
1708 1,366 9 937-1 20, 480
1688 1,357 Io 802. 5 19,114
1668 1,333 Ir 682. 7 17,757
1628 1,316 12 577-5 | 16,424
1519 1,258 13 486.6 | 15,108
L491 1,241 14 4lo.1 | 13,850
1269 1,126 15 345-5 12,689
1030 996 16 292.5 11,483
0844 896 17 249. 2 10, 487
0674 787 18 213-6 9) 59L
0475 648 19 184.3 8, 804
0328 2,653 20 159: 7 8,156
0124 1,560 25 78.9 5 503
0042 1,714 30 43-2 31943
0016 969 40 13-7 2,229
0003 485 50 4.6 1,260
e002 263 60 7 775
O00T 165 70 “4 512
diate 347 Bo +O 347
2,874.4 34,020 |]........ a asuseayenbeba lieve ae! wane
1 By a “‘point”’ is meant a decrease in density of one part per million. The density of water at 6.1 as compared wi
at 40° is 0.999965. ‘The loss in density is, therefore, 0.000035 and this represents the loss in weight of the ienrersiince ake af
6.r°, and, therefore, is one factor in determining the work to be done in pushing it down into deeper and cooler strata. For con-
veniense in computation this factor is taken as a positive quantity and a whole number is stated as 35 points. (See Birge, 1916,
PD. 391. * — :
FINGER LAKES OF NEW YORK. 221
DISTRIBUTED WORK.
Table 4 deals with the direct curve of work. It gives for each stratum the amount
of work necessary to convey the warmer and lighter water from the surface to the
depth in question, assuming that the lower water has a temperature of 4.0°. In warm-
ing all strata below that at the surface most of the work is performed in the strata
above that for the benefit of which the work is done. If the work for each stratum is thus
distributed to the several strata above it, we derive the curve of distributed work. (See
Birge, 1916, p. 355). This is shown for the mean of each lake in Table 6 and for Seneca
Lake in figure 3. The numbers for each stratum show how many gram centimeters
are necessary to distribute through the stratum the heat retained in it and to convey
through it the heat which goes on to lower strata. The table shows how shallow is
the stratum which receives most of the work of the wind. More than 94 per cent of
this work is expended in conveying the heat through the upper 20 m. of the lake. While
the effect of the wind extends to the bottom, even in Seneca Lake, the work done in
the deeper water is very small, as measured by the fall in density due to increased tem-
perature. In the upper 5 m. are found from 43 to 50 per cent of the work and in this
stratum the largest deductions from the apparent work are to be made for the influence
of direct insolation.
TABLE 6.—DISTRIBUTED WorRK, MEAN.
- [NotE.—This shows work done in each stratum in distributing the heat brought to it, and in carrying on to the next stratum the
heat which passes through it. This is computed only for the means of the lakes.)
Canandaigua Lake. Cayuga Lake. Seneca Lake.
Depth in meters.
G.cm. |Percent.| G.cm. | Per cent.} G.cm. | Per cent.
+
on
<a Ss SE eS
HORKHODHUO
4
a
>
an
1,245.0
826.9
Hh
eS
wa
°
La BE Oe BS
ewWOHMNDO OP
SUBTRACTION CURVES.
Table 7 shows the data for the mean subtraction curves of the three lakes. (See
Birge, 1916, p. 384.). It shows the number of calories which pass through the several
levels of the lakes and the amount of work needed to distribute them through the water
below these levels. Comparison of the data at the surface shows that 12 to 14 cal. of
heat are distributed through the subjacent water by 1 g. cm. of work. At lower levels
the temperature declines and the decrease in density falls off even more rapidly with
the result that an increasingly large number of calories -is distributed by 1 g. cm. of
work. At the depth of 10 m. the ratio is 25 to 30 cal. to 1 g. cm.; at 20 m. the ratio
rises to 40:1 or 50:1; at 30 m. in Seneca Lake and at 4o m. in the others it has risen
nearly or quite to 100:1. This relation explains how in lakes of great depth a large
quantity of heat is carried in spring to the lower water. The great quantity of work
222 BULLETIN OF THE BUREAU OF FISHERIES.
needed for distribution in the upper water as the temperature rises equally makes clear
the reason why the lower water soon ceases to gain heat as the season advances.
In Seneca Lake work amounting to only 0.4 g. cm. is needed to distribute 512 cal.
to depths below 70 m., while no appreciable amount of work is needed to distribute 347
cal. through the water below80m. The last statement is obviously not strictly accurate,
but it is not worth while to compute the work in those cases where the decrease in den-
sity due to increase of temperature is less than one part per million.
TABLE 7.—SUBTRACTION CURVE Means: AMOUNT AND PER Cent or Heat in SUMMER Heat INCOME
AND OF WorRK NECESSARY TO DISTRIBUTE THIS Heat FOUND AT THE SURFACE AND AT DIFFERENT
DEPTHS OF THE SEVERAL LAKES.
[Nore.—Stated in units per square centimeter of the surface of the lakes.]
Canandaigua Lake. Cayuga Lake. Seneca Lake.
Depth in meters. = 7
Cal. P.ct. |G.cm.| P. ct. Cal. P.ct. |G.cm.| P. ct. Cal. P. ct. |G.cm.], P. ct.
34,020
26, 220
29, 480 100.0 2,446
15,480 52-5 47 19, 120
9,980 33-8 280 12,610
6, 380 21.6 143 8, 160
3,280 II-t 46 3,960
1,880 6.4 18 2, 260
1,110 3-8 8 I, 320
700 2-4 4 900
440 1-5 2 630
280 1.0 ° 45°
90 2S fewcscoee 190
HEAT AND WORK AS MEASURED AT DEPTH.
In Table 7 the data are given in terms of the surface of the lake—so many calories,
or gram centimeters, per square centimeter of surface. If the datum plane is taken
as the area of the lake at the depth in question, the number of calories and gram
centimeters at each level will be increased proportionally to the decrease of area as
compared with that of the surface; but the ratio between the amounts of work and of
heat would remain unaltered. ‘This relation is shown in Table 8. Perhaps the most
interesting fact shown by it is the very close agreement between Cayuga and Seneca
Lakes in both heat and work after the surface level is passed. Approximately equal
quantities of heat pass through the 5 to 4o m. levels of both lakes. Cayuga Lake shows
at the surface considerably less heat per unit of area than Seneca has, but this is largely
due to the great area of shallow water at the north end of Cayuga Lake. No such area
is found anywhere in Seneca Lake. The area of Cayuga Lake at 5 m. is about 79 per
cent of the surface area, while that of Seneca Lake at the same depth is 87 per cent of
the surface. The area of the 10 m. level in Cayuga is about 92 per cent of that at 5 m.,
and in Seneca about 93 per cent of the 5 m. level, a very close correspondence, which
shows itself in the heat and work. The large area of shallow water in Cayuga Lake
adds nothing to its effective area in absorbing heat, nor does it seem to diminish the
efficiency of the lake. Canandaigua Lake, however, is plainly less efficient than either
of the others. Its smaller area and higher banks cause this condition, since both factors
lessen the efficiency of the wind. (See Birge and Juday, 1914, Pls. CXIII, CXIV, CXVI.)
FINGER LAKES OF NEW YORK. 223
TaBLE 8.—AmoUNT OF Heat In SUMMER Heat INcoME AND WorK NECESSARY TO DISTRIBUTE I’.
{Nore.—Expressed in units per square centimeter of the depth in question; not (as in other tables) in units per square centimeter
of the lake surface.)
Canandaigua Lake. Cayuga Lake. Seneca Lake.
Depth in meters.
Cal. G. cm. Cal. G. cm. Cal. G. em.
ONS as 24 SERA bE Te Aare as eae See amt Gak eed 26, 980 1,929 29, 480 2,446 34) 020
LURID ee ae Cet ter Race Meret cK ROMP noe ney re wear 22,970 1,150 275750 1,710 28, 000
EO sires is: ate’ Soe elesataretengeteiibe wie a: loqnaeaclalstclosnenenes Ve Gar Gene eb ealevasavegenegsbayees Stasi gusi det 16, 540 549 21) 440 892 21,900
. 14, 530 406 14, 900
9, 800 220 10, 100
51420 76 5,190
31440 33 3,150
2,330 17 1,980
1,640 9 1,480
1,150 5 I,IIo
“B20 fives ci na ves 840 |...
r 420 |..
wee sgeae 2 ; 170 |..
‘ go }..
Sioa Re AGS Rie Hee eee ae °
ABSORPTION OF SUN’S ENERGY.
Observations were made in 1918 on Seneca, Cayuga, and Canandaigua Lakes in
order to ascertain the rate at which the energy of the sun’s rays is absorbed by the
water of the lakes. The instrument is described in another paper (Birge, 1921),
and the description will not be repeated. It consists of a receiver containing 20 small
thermal couples which can be lowered into the lake to any desired depth and alternately
exposed to the sun and covered. ‘The electrical effect of the sun’s radiation on the ther-
mal couples is proportional to the energy in its rays, and the resulting electrical cur-
rents are measured by the deflections caused in a d’Arsonval galvanometer. The
galvanometer is kept on shore and is connected with the receiver by an insulated cable
100 m. long. :
The observations on the three lakes afford excellent illustrations of the results
obtainable by this instrument, and also of the difficulties which necessarily attend
observations of the kind if made in the course of a short visit, when every opportunity
must be fully used. The general results from each lake are clear and unmistakable,
but in each case the details are affected by special conditions of sky or water.
A part of the observations on Seneca Lake is given in Table 9 in order to show the
nature of the data.
224 BULLETIN OF THE BUREAU OF FISHERIES.
TABLE 9.—TRANSMISSION OF SUN’S ENERGY BY THE WATER OF SENECA LAKE OrF HECTOR PoINnT,
. Y., Au. 1, 1918.
[NorE.—1.so to 2.23 p. m., Government time=12.40 to 1.11 sun time, ‘Transparency 6.8 m.]
Depth Depth
Hour, p. m. ae Zero. gag ae Hour, p. m. een | Zero. Pog oe
meters. meters.
on lee re FES | ROPe accuse aeunemnveanatan aceetye 400 ee 8 17-5
25 me ie 9053) || B00 esha yo ce aseeae Ges Sasa 500 oe 7 one 11-9
50 a as 640, ||Sottascuiseind neuigenamerds oem 600 ie aoe 8.3
100 ee pee 96% ll BEd ss rdarniadecssiaeas Joo ees pe 5:9
150 ine ae } eg Bie: | any coda save ssaueyinaneektend oe sieves 800 aes oe 4.0
200 bi pone SSPE No .18 catia sa siotesewbinntay salwene goo a te : 2.9
oof 2) 4001} as ae
300 ine ie 242 |i y 2B acai nd HateMeGies 445 aera 1,000 aa 4 te 2.2
sof jer] serif 2° ea cae
NOTES ON ABOVE TABLE.
a. Sky perfectly clear and sun’s radiation steady; no clouds; practically no haze. Light south
air, causing ripples on surface. Some swell from wind of yesterday and of early morning. The
swell caused irregularities of reading in upper water, as it raised and lowered the boat. At 100 cm.
the scale moved over 4 to 5 divisions, and reading had to be estimated under these conditions. This
effect became less as depth increased. Ripples cause a quivering of the reading i in the gelvatiometer
but are too small to cause swings of the scale.
2. In reading the direct sun a shunt coil is included in the circuit in order to keep the reading
within the limits of the scale. This coil is cut out by a switch when the receiver is used in water. The
reading in air must be multiplied by 1.89 to reduce it to the same scale as those in the water. Its value,
therefore, on this occasion is 221 divisions. One division equals 0.059 cal./cm.?/min., so that the sun
was delivering about 1.30 cal./cm.?/min.
3. The observations not reported included a repetition of several of the readings, and'a second
reading in the air, which gave a value of 116.2 divisions, or substantially the same as the first reading.
4. The numbers in the columns headed zero, reading, deflection, indicate divisions of the scale of
the galvanometer.
From these readings may be computed the value of the energy delivered by the
sun at different depths of the lake, as is shown in the following table:
TABLE 10.—CALORIES PER SQUARE CENTIMETER PER MINUTE FouND at VARIOUS DEPTHS OF SENECA
Lake, AUG. 1, 1918.
Depth in centi- Cal./em.?/ Depth in centi- 4 Cal./cm.2/ Depth in centi- Cal./cm.?2
meters. Per cent. | “min. meters. Per cent. | “iin. meters, Beticent: oe :
100. 0 1.30 12.8 O17 2,27. 0.035
31.8 +4 10.9 +14 18 +023
29.0 38 9.0 12 L3 O17
a1. 4. 28 7-7 10 10 013
17.4 +23 5.4 o7
15.0 -20 3.8 +05
FINGER LAKES OF NEW YORK. 225
TABLE 11.—TRANSMISSION OF SUN’S ENERGY PER METER OF DEPTH.
(Nore.—Per cent of the energy found at the upper surface of each 1 m. stratum which is present at the lower surface of such
stratum.]
Trans- Trans- Trans-
Stratum in meters. mission, Stratum in meters. mission, Stratum in meters. mission,
per cent. per cent. per cent,
OOD iid nastics aio’ 83s Se atwroaund oe 24 6956: |] BHGiss secrsisesconss waver lat 72.2
70.2 69. 8 |Get is. smeaccins cae ce ainanenaGiet 75-9
72.6 91.1
71.0 67.8
Table 11 is given as it stands in order to bring out the various small variations in
percentage which are inherent in the observations. In all cases the fraction of a
division of the galvanometer scale must be estimated and is, therefore, subject to error.
The value taken as zero is not a fixed one and in any observation may be recorded
slightly too low, or more probably a little too high. The motion of the boat, due to
the swell, as stated above, might introduce some errors in this case, especially in the
readings from the upper water. In figure 2 the results are plotted and a smooth curve
a-a is drawn through them. All of the observations are very close to the curve. It
is plain that there was transmitted through each 1 m. stratum of water below the surface
meter about 71 per cent of the energy received at its upper surface. It is not probable
that the higher transmission indicated in the 9 to 10 m. stratum has any significance.
A reading of 2.1 divisions of the scale at 10 m. instead of 2.2 divisions would bring this
interval into line with the others.
Lake water differs widely from pure water in the quantity of energy transmitted.
If we assume a solar energy curve corresponding to a path of the rays in the air of 1.5
atmosphere, with about 0.5 cm. condensable water in the atmosphere, about 47 per
cent of the solar energy will be left after passing through 1 m. of pure water. The water
of Seneca Lake, therefore, cuts off about 25 per cent more than does pure water and adds
one-half to the loss due to pure water. Pure water transmits through the 1 to 2 m.
stratum nearly 80 per cent of the energy reaching its upper Jevel and over go per cent
passes through all deeper 1 m. strata, the loss per meter rapidly declining to a minimum
of about 2 per cent of the energy incident on the upper surface of the stratum. At
5 m., therefore, there would remain about 29 per cent of the original energy of the sun
and about 23.4 per cent at 10 m. instead of 5.4 per cent and 1 per cent found in Seneca
Lake. This wide difference between pure water and the lake water is probably due
chiefly to matter suspended in the water of Seneca Lake, since there is very little stain
present in the water. The suspended matter is partly organic but chiefly fine silt
derived from the soft shales that constitute much of the shores.
In pure water the transmission through the 1 to 2 m. stratum is much smaller than
in those below. This is due to the rapid absorption of the rays of the red end of the
spectrum as compared with the slow absorption of the shorter waves. No such effect
uuseems to be present in the Jake, nor is it ordinarily demonstrable in lakes. Sometimes,
but not commonly, the deeper strata of a lake show a transmission 1 or 2 per cent higher
than the 1 to 2 m. stratum, but in general the transmission in that stratum is nearly
the same as in those immediately below. This means that the large nonselective ab-
46104°—21——-3
226 BULLETIN OF THE BUREAU OF FISHERIES.
sorption due to turbidity and the selective absorption due to stain obscure the selective
absorption of the water, as water, after the first meter has been passed. In that meter
of water is absorbed practically all of the energy contained in that part of the spectrum
Per cent 6 10 16 20 26 30
y
s tif
/
tL
if
/
4
|
—~
ol
Fag. 2.—Curves of transmission of sun’s radiation, Seneca Lake, Aug. 1, 1918. ‘The vertical axis gives depth and the horizontal
axis gives per cent of the total radiation of thesun. A-A, direct observations; B-B, verticalsun; C-C,mean sun. Thesun’s
rays passed through a thickness of 100 cm. water of the lake at the depth of94em. Dotsare placed corresponding to this depth
on the curve A-A, and from these is plotted the curve B-B, for thesun in the zenith when depth and stratum traversed by
rays are equal. ‘The rays pass through a mean distance of 115 cm. during the warming season in reaching a depth of 100 cm.
These points are marked on the curve B-B, and from them is plotted the curve C-C or the curve of meansun. (See Table
12, Pp. 228.)
lying below the A line which is commonly taken as the lower limit of the visible spec-
trum.
The general result of these observations is, therefore, plain. Under the conditions
of the time and place 21 to 22 per cent of the sun’s energy delivered to the surface was
FINGER LAKES OF NEW YORK. 227
present at a depth of 1m. In the deeper 1 m. strata there was a loss of 28 to 29 per
cent of the energy present at the upper surface of the stratum. At 5 m. depth there
remained about 5.4 per cent, and at 10 m. about 1 per cent of the energy delivered to
the surface.
We may infer from such a set of observations the penetration of the sun’s rays
during the whole day or during a longer period, assuming that the turbidity and color of
the water remain unchanged. In such a process it is not hard to secure results which
are correct in general, but it is impossible to secure minute accuracy. Certain, though
not all, of the facts which prevent minute accuracy will be mentioned.
1. Sunlight is a mixture of the direct rays of the sun and of rays reflected from the
sky. The percentage of sky radiation is very variable, being sometimes as low as 8 per
cent of the total radiation and rising nearly to 100 per cent when the sun barely shines
through haze or cloud. The quantity of energy reflected from a unit area of sky is also
variable and differs with the nature of the sky and the proximity of the area to the sun.
The mean percentage of sky radiation reflected from the surface of the water differs
from that of the direct rays, and the mean path in water of the rays from the sky differs
from that of the direct rays. It is practically impossible, under the conditions of ob-
servations on lakes, to determine either the amount or the distribution of the sky radia-
tion. It is, therefore, impossible to make full correction for the elements in the mixture
of direct and diffuse rays at the time of observations.
2. It is also impossible to make such corrections for longer periods, since the aver-
age amount of sky radiation is still quite unknown for most places, and is not accurately
known anywhere.
3. No correction has been made in the observations for radiation reflected from the
surface of the water, but the readings at 1 m., etc., have been compared directly with the
reading in air. The direct sun radiation, at the altitude of the sun when the observa-
tions were made, would lose about 2.1 per cent by reflection. The sky radiation would
lose 17.3 per cent if equal quantities came from equal areas of sky. ‘This loss at the
surface, which can not be known accurately, has been balanced against the opposite
effect of the hemispherical glass cover of the sunshine receiver. There would be about
4 per cent of the sun’s radiation reflected from this in air and about 0.5 per cent in water.
In computing a standard curve of absorption for Seneca Lake, all radiation has
been referred directly to the sun, and the path of the rays in the water has been computed
on that basis, from the following elements:
Time of observations, August 1, 1918, 12.40 to 1.11 sun time.
Corresponding altitude of sun, August 1, 64.1 to 62.3°-
Depth at which sun’s rays pass through 1 m. of water, at first observation, 94.5 cm; at last observa-
tion, 93.7 cm.; mean 94.1 cm.
On the curve of direct observations (A—A, fig. 2) are noted the readings at the dis-
tances corresponding to this path of the rays in water. These periods are plotted and
connected by a new curve, B-B, the curve for vertical sun. In this curve, which assumes
a sun in the zenith, the depth below the surface equals the length of path of the rays in
reaching that depth. This constitutes a standard curve, from which may be derived
the energy which remains at given depths below the surface at any time of the day or
year, provided the altitude of the sun is known and the corresponding length of the
path of its rays in water. It must be assumed also that all radiation comes directly
228 BULLETIN OF THE BUREAU OF FISHERIES.
from the sun, or at least that the value of the sky radiation is the same as at the time
of observation.
The results are stated in Table 12, vertical sun.
The mean distribution of sunshine and cloud at Seneca Lake is not known, but at
Madison, Wis., the mean daily supply from sun and sky during the five months April
1 to August 31 is 398 cal. The mean path of the rays during this period to reach a depth
of 100 cm. below the surface is 115 cm. In this computation allowance is made for
reflection from the surface in excess of 2.1 per cent; all radiation is supposed to come
from the sun; and the form—though not the area—of the solar energy curve is supposed
to be constant.
The points corresponding to this distance of 115 cm. per 100 cm. of depth are noted
on the curve for vertical sun, carried up to their proper place, and a third curve, C—C,
figure 2, is drawn, which is the curve for mean sun (Table 12).
TABLE 12.—TRANSMISSION OF SuN’S Rays BY WATER OF SENECA LAKE, AUG. 1, 1918. (See fig. 2, p. 226.)
Per cent radiation remaining Per cent radiation remaining
at depth indicated. at depth indicated.
Depth in centimeters. Computed per cent. Depth in centimeters. Computed per cent.
Observed Observed
per cent. | Vertical Mean per cent. | Vertical | Mean
sun, sun, sun. sun.
21.4 21.9 20.7 3.8 44 3-3
15.0 15.6 14.3 ler 3.2 2.3
10.9 IL § 9.9 18 2.3 1.6
7 8.3 6.8 tg) 7 1.0
5.4 6.0 47 Lo Ez “7
This curve of mean sun and Table 12 show that in Seneca Lake at 1 m. depth there
is found an average of about 20.7 per cent of the incident radiation and that each 1 m.
stratum below transmits less than 70 per cent of the radiation received by its upper
surface. The water has absorbed 99 per cent of the incident energy at about 9 m. as
compared with about 10 m. for the observed curve and 11 m. or more for the curve of
vertical sun.
The difference in the three curves are not striking in this case; but if the observa-
tions had been made at an hour farther from noon, or later in the season, the difference
would have been correspondingly larger.
It must not be supposed that this mean sun curve represents exactly the mean con-
ditions actually present during the period when the lake is warming. ‘The transparency
of the water is variable and the sun’s penetration varies with it. No account is taken
in this curve of the energy received during cloudy hours. Yet after all deductions are
made it remains true that the curve gives a generally correct picture of the actual direct
delivery of the sun’s radiation to Seneca Lake so far as a single observation can give
this. Hardly more than 20 per cent of the incident energy is delivered to water below
the surface meter. Not over 5 per cent is delivered to a greater depth than 5 m. and not
over 1 per cent below 10m. Evena considerable increase in transparency would leave
these figures, not unchanged, but of the same order of magnitude.
Observations such as these are ordinarily made at times when the sky radiation is
relatively small—near noon of clear days. When, therefore, such an observation is
FINGER LAKES OF NEW YORK. 229
used as the basis of larger conclusions and when in computing the results all radiation
is assumed to be direct, the effect of the direct rays of the sum in warming the lake is
placed at a maximum. In the preceding paragraph all radiation is supposed to come
directly from the sun. In fact at Madison about 16 per cent of the total radiation
Oo __G.em. 60 100 180 200 250 B_ 200
a
—
—0
mn. —
2K
o
10 L
1B 7”
35.
FEC
Fic. 3.—Work curves of Seneca Lake, mean temperature. The vertical axis shows depth; the horizontal axis shows gram centi-
meters of work per meter of depth and square centimeters of surface of lake. OCC, curve of direct work. About rq5 g. cm.
of work, for instance, are necessary to carry the heat of the 9 to 10 m. stratum from the surface and put it in place. BDE,
curve of distributed work, derived from OCC, showing the amount of work done in each 1 m. stratum. The area OBEFO
(distributed work) is equal to the area OCCFO (direct work). ODD shows the contribution of the sun in distributing the
sun’s energy. The area ODDBO gives the contribution of the sun, and that of the wind is represented by the area ODEFO.
(See Table 16, p. 235.) :
received April 1 to August 31 comes during cloudy hours, and about 16 per cent more
comes from the sky during sunny hours. The direct sun, therefore, supplies only about
two-thirds of the radiant energy received by the lake. It may be assumed that during
cloudy hours equal areas of sky supply equal amounts of energy to a surface normal to
the rays. On this basis, and allowing for reflection from water surface, the mean path of
230 BULLETIN OF THE BUREAU OF FISHERIES.
the diffuse radiation in reaching a depth of 100 cm. would be about 126 cm. as compared
with 115 cm. for the direct rays. The mean path for sky radiation during sunny hours
would be between the numbers given above, depending on the relative amount of the
sky radiation coming from areas close to the sun and, therefore, having approximately
the same length of path in the water as the sun’s rays have.
In the absence of knowledge of the amount of sky radiation at Seneca Lake, either
general or on the date of observation, no correction can be made for sky radiation.
Such correction can be made where observations are so numerous that it may safely be
assumed that sky radiation was the mean amount. ‘This is the case with Lake Mendota,
and the best computation that can be made shows that the mean path of all rays to reach
a depth of 100 cm. in the period of April 15 to August 15 is about 118 cm. No essential
difference, therefore, is made in the results if all radiation is attributed to the sun with
a mean path of 115 cm., as has been done in the previous paragraphs.
The observations on Canandaigua and Cayuga Lakes may be treated much more
briefly. They were taken at the same intervals as on Seneca Lake but to the depth of
5 m., which is ample for the determination of the rate of absorption. The results are
shown in figures 4 and 5, and summarized in Tables 13 and 14.
TABLE 1 3.—TRANSMISSION or RapraTIon BY WatER oF CayuGa LAKE, SHELDRAKE Porn’, Juuy 29,
1918, 1.45 TO 2.45 P. M., GOVERNMENT TIME. (See fig. 4.)
(Nove.—Sky with cumulus clouds drifting across; clear between clotids. Transparency of water 6.2m. ‘Transmission per
meter about 66 per cent.)
Per cent radiation remaining at depth Per cent radiation remaining at depth
indicated. indicated,
Depth in centi- Computed per cent. Depth in centi- Computed per cent.
meters. Mean meters: M
Mean
eal Observed : apace observed
"| per eent.| Vertical | Mean per cent: | ber cent.| Vertical | Mean
sun. sun. sun. sun.
|
Ig. 2 IQs 4 19-9 17-9 : 6
WOO. cece c ee cec ene 19.6 \ FOO cece cece eer eee { ou } 5:5 6.1 49
13-4 : 3-6
BOO echieayenslaiak 5% 85 II-3 12.8 13-3 11.9 H 34
II-4 | BOOK. 4 dsianciscnntagsns vas 36 3-6 aol 3-1
8.1 8.4 9.1 7.6 ; 8 H
BOG va eitacireinainaiaas Be 8.6 : .
i
oO Gen. 80 100 150 200 20 =B a00
— ——
~ a Lo
Fic. 4.—Work curves for Cayuga Lake. (See explanation, fig. 3.)
The observations on Cayuga Lake are rendered somewhat irregular by the fact
that numerous white cumulus clouds were passing over the sky and work had to be
done when the sun was in the spaces between the clouds. Under these conditions the
FINGER LAKES OF NEW YORK. 231
radiation from the sun is sure to be variable; the approach to the sun of a white cloud
momentarily raises the radiation and unnoticed wisps of cloud may reduce it. In
the series it is clear that the mean of the readings at 200 cm. is too low as compared
with all of the others, since.the transmission in the 1 to 2 m. stratum should be about
the same as below. The value of 12.8 per cent has been assumed, therefore, for the 200
cm. level and a mean transmission of about 66 per cent per meter. Under these condi-
tions about 99 per cent of the sum’s energy would be delivered to the upper 8 m. of
water, somewhat more than 80 per cent going to the first meter, or with mean sun about
82 per cent.
It will be noted that corresponding with the smaller transparency of the water, as
compared with Seneca Lake, the transmission of radiation is decidedly lower.
TABLE 14.—TRANSMISSION oF SUN’s ENERGY BY WATER OF CANANDAIGUA LAKE, JULY 27, 1918, 11.37
A. M. TO 12.03 P. M., GOVERNMENT TIME. (See fig. 5.)
[Nore.—Sky hazy. Transparency of water 4.4m. Transmission pet meter about 60 per cent.]
| Per cent radiation remaining Per cent radiation temaining
at depth indicated. at depth indicated.
* =~ LJ
Depth m cetitimeters. Computed per cent. ||. Denth in centimeters. Computed per cent.
Observed Observed
per cent. | Vertical | Mean per cent. | Vertical | Mean
sun, sun, sun. sun,
BOG oo schnacshaiaiortaye dd odtornrbateruie aie 18.7 19.4 OE AO sited dine Aan aRaWaemaine Hine 4.2 4.8 3.7
BOs sis aa srareraverauajare ace bieie setae rales es 11.3 12.2 TO. 7 |] SOO... cere cece ee eter eens 3.1 3.1 2.2
BOO a ois sadeershatna teased Getieareltiecsiares @ 6.9 8 6.3
O_G.cm. 50 100 180 200 B_ aso
a oe eee er ene oe
Cm
“J
mY
} D
A
‘ Lh
4,
we
iA
10 sant
Fic. 5.—Work curves for Canandaigua Lake. (See explanation, fig. 3.)
The observations on Canandaigua Lake were also somewhat irregular, not on
account of clouds, but haze. The sky was cloudless, but the hills a few miles up the
lake were nearly invisible in the haze which filled the valley. Under such conditions
the value of the sun’s radiation is much reduced, and it was found to be about 0.95
cal./cm2/min. as compared with 1.30 cal. in the case of the two other lakes. The read-
ings of the sun at the beginning and end of the observations in the lake were in close
agreement. The readings of the first series taken in the water—those taken while
the receiver was going down—were also in close agreement and indicate that 18 to
19 per cent of the radiation in air was present at 100 cm. depth and that each meter
below that depth transmitted about 60 per cent of the radiation received by its upper
232 BULLETIN OF THE BUREAU OF FISHERIES.
surface. At 500 cm., however, the reading rose so that the transmission seemed to
rise to about 74 per cent. The second set of readings—those taken while the receiver
was being raised—again indicated about 60 per cent transmission but showed at all
depths a higher percentage of the radiation at the surface, amounting at 100 cm. to
21 per cent. Comparison with the other lakes shows that the lower value at 100 cm.
is to be chosen, as the transparency of the water is decidedly less than in either Cayuga
or Seneca Lakes. ‘The haze must have become slightly thinner during the later readings
in the water but thickened again before the second reading in the air. The accuracy
of the value at 100 cm. must remain somewhat uncertain under the conditions of sky
then prevailing. Since the value of the radiation may alter during haze almost from
minute to minute with no visible indication of change, such as cloud offers, it would
need a very large number of readings to show whether 18 to 19 per cent or a slightly
lower figure should be taken as the value for mean sun at 100 cm. ‘The error is not
likely to exceed 1 per cent in any case, nor is it large enough to affect general relations
of sun to the distribution of heat.
Under these conditions 99 per cent of the sun’s energy would be delivered to the
upper 6.5 m. of water.
We may now put togetlier the general results from the three lakes in which observa-
tions were made.
TABLE 15.—TRANSPARENCY AND TRANSMISSION OF RADIATION—VERTICAL SUN.
Trans- | Per cent pe
parency at 100 sat
a centi- | Mission
meters. | meters. ater
Seneca Lake 21.9 72
Cayuga Lake... ... 6.2 19.9 66
Canandaigua Lake. 44 19. 4 60
In these cases there is some parallelism between the percentage of transmission
and the transparency of the lake. This is due to the fact that all these lakes have water
which is only slightly stained and which does not differ greatly in color. In general
there may be little correlation between transparency and rate of transmission.
WORK OF THE SUN IN DISTRIBUTING HEAT.
From the data at hand it is possible to make a general estimate of the part which
the sun plays in distributing the heat gained by Seneca Lake as its summer heat income.
We have as data (a) the amount of heat so gained as the mean of four seasons; (b) the
amount and the distribution of the work necessary to carry this heat through the lake,
assuming that all work is done by the wind; (c) the actual amount of heat delivered
into the water of the lake directly by the sun on one date, and the conclusions drawn
from these observations in the preceding paragraphs. We lack as data (a) the total
amount of heat delivered to the lake during the period when the summer heat income
is gained; (b) the losses of heat during this period from different strata near the surface.
The absence of the data specified and others as well make it impossible to state
the réle of the sun with any approach to exactness. But it is possible to make esti-
FINGER LAKES OF NEW YORK. 233
mates which will show the general situation and in our almost complete ignorance of
the subject, such statements are not without value.
We take, therefore, as the summer heat income of Seneca Lake 34,000 cal./cm.?
of surface. Of this sum, 32,400 cal. are found below 1 m.; 28,000 cal. below 5 m.;
and 21,900 cal. below 10 m. These figures are based on the calories found per square
centimeter of the depth in question, and not those per square centimeter of the
surface. In computing the relative work of sun and wind these figures must be
used, since the sun’s radiation which passes through the shallow water is absorbed by
the bottom of the lake.
The distribution of this heat, attributing all work to the wind, requires about
2,874 g. cm. of work per square centimeter of the lake’s surface. This work is distrib-
uted (fig. 3) at the rate of about 290 g. cm./cm.? of the surface at the surface; 270
g. cm./cm.? at 1 m. depth; 202 g. cm./em.? at 5 m.; and 125 g.cm./em2 atiom. In
the upper 5 m. there is done about 45 per cent of the total work; about 33 per cent
in the 5 to 10 m. stratum, both of which are within reach of the direct influence of the
sun; about 20 per cent more of the work comes in the 10 to 15 m. stratum.
Applying the experience gained from observations on Lake Mendota, it may fairly
be assumed that Seneca Lake receives about 65,000 cal./cm.? of surface during the
period of the summer heat income. ‘The lake loses, therefore, about one-half of the
incident heat.
If we apply the mean sun data of Table 12 to this gross income, the sun delivers
during this period about 13,400 cal. to the depth of 1 m.; 3,000 to 5 m.; and 450 to
10m. ‘These numbers are, respectively, 41 per cent, 11 per cent, and 1.9 per cent of
the quantity of heat which passes through these levels. (See Table 7 for quantity of
heat.)
The work attributed to the wind at these depths would be diminished by the aid
of the sun in the same ratio that the heat delivered by the sun bears to the total amount
of heat passing through those levels. Computed on this basis, the sun does all of the
work of distributing heat at the surface, 41 per cent at 1 m. depth, 11 per cent at 5 m.,
etc. These quantities may be plotted as on figure 3 (p. 229) and the points connected
by acurve. Then the area ODBO is proportional to the total work done by the sun
under the conditions assumed. ‘This area may be measured with a planimeter. It is
equal to about 16 per cent of the area representing the total work. The part of it
below 1 m. is about 10.9 per cent of the work done below 1 m. of depth.
This represents the maximum possible aid which, under the conditions assumed,
the sun can give in the distribution of heat, for it assumes that the entire loss of inci-
dent radiation by the lake, amounting to one-half of that received, falls on the wind-
placed heat and that no loss falls on the sun-placed heat. This assumption is evidently
not correct. If, instead, we assume that the sun-placed heat suffers equal losses with
that distributed by the wind, the aid of the sun will be reduced to about 8 per cent
of the total work done and to about 5.5 per cent of the work done below 1 m.
Probably the assumption of equal losses is unfair to the sun. A great part of the
lost heat is in that which is absorbed by the thin stratum at the surface and is used in
evaporation, lost to the air at once or during the following night, etc. Almost all of
the heat in the longer waves of the spectrum is absorbed by a much thinner layer of
234 BULLETIN OF THE BUREAU OF FISHERIES.
water than 1 m. Schmidt (1908, p. 240) computes that about 27 per cent of the solar
energy is absorbed by 1 cm. of pure water and about 45 per cent by 1 dm. He uses
Langley’s energy curve for the solar spectrum, which makes his figures somewhat
larger than would be the case in a curve for moderately high sun. In the curve which
we have used as standard (path of rays equals 1.5 atmospheres) about 43 per cent of
the energy would be absorbed by 25 cm. of pure water and 49 percent by 50cm. While
no great accuracy can be claimed for the figures shown by Seneca Lake of about 67 per
cent absorption for 25 cm. and 72 per cent for 50 cm., they are probably not greatly
in error. The differences between them and the data for pure water are much the
same as for greater depths. Thus more than one-half of the sun’s energy is delivered
to the upper centimeters of water from which loss to the air is easy. But much of the
heat so delivered is distributed by the wind from the surface strata to deeper water,
especially in the early part of the warming season when the lake is gaining heat rapidly.
From this source comes the greater part of the heat which the lake gains below 1 m.
in excess of that delivered by the sun. This heat amounts to 19,000 cal./em.’ and much
of it must come from the 40,000 cal./cm.?, or more, absorbed by the upper 25 cm. of
the lake. During bright and windy days there must be thus moved down into the
lake by the wind much héat which is lost during cool periods when the whole upper
water of the lake cools down.
It is true that on the whole the heat delivered by the sun to strata below the surface
is more likely to be retained, as the water above a stratum must be cooled to a lower
temperature than the deeper water before any heat can be lost by the latter. But
several times each season there is a general cooling of the upper water, when much
heat is lost, that placed by the sun as well as that placed by wind.
At present, therefore, no accurate estimate can be made of the loss of sun-placed
heat at various depths. The subject must be left here with the general statement
that between 84 and 92 per cent of the work done in distributing heat through the water
of Seneca Lake is performed by the wind, on the assumption that conditions of trans-
parency, etc., on August 1 were average ones. The amount really attributable to the
sun is probably as much as 10 to 12 per cent. More than this can not be said, both in
view of considerations presented above, and also in view of one other consideration
which the study of Lake Mendota has shown. In the early part of the warming period,
when gains of heat are rapid and when the deeper water is securing most of its heat,
the sun plays a small part in distributing the heat. Later in the summer the sun has
a much larger share of the work, when the epilimnion is forming, when gains of heat
are small (perhaps only 5 to 10 per cent of the incident radiation), and when these
gains are confined to the surface strata.
The foregoing paragraphs have dealt with Seneca Lake alone. ‘The same methods
may be applied to the other lakes with similar results. It is unnecessary to give the
details of the computations; the results are shown in Table 16 (p. 235) and figures 4
and 5 (pp. 230, 231).
FINGER LAKES OF NEW YORK. 235
TABLE 16.—DIvISsION oF DistRIBUTION OF SUMMER Heat INCOME BETWEEN SUN AND WIND IN THE
LAKES AS A WHOLE AND IN THEIR SEVERAL Strata. (See figs. 3, 4, 5, and text.)
(Nore. —In this table, as elsewhere in this paper, “‘ work’ means the total work which would be needed to distribute the heat
from the surface of the lake through the adjacent water, computed on the assumption that all heat is put into place by the
wind mixing the warmer surface water with the cooler water below. In the division of the task of distributing heat between
sun and wind it is also assumed that all losses of heat fallon wind-placed heat. This evidently attributes too large a share
» pe oni Pia a fair estimate would be to allow to the sun all that it does below 1 m., i. e., about 10 to 11 per cent
ol e tol
Canandaigua Lake. Cayuga Lake. Seneca Lake.
Sun. Wind. Sun. Wind. Sun. Wind.
Per cent, | Per cent. | Per cent, | Per cent. | Per cent. | Per cent.
"Total work sighs sich seeecisostsihy aa ps aaacene de da aa see lela ys des pasiepete 16.9 83.1 15.0 85.0 15.8 84.2
Work, otosm... isa 31.6 68. 4 33-1 66.9 32.0 68.0
Work, 5 to 1om 2.9 97.1 4.6 95-4 6.6 93-4
Work, otorm. 62.3 37-7 60. 8 39. 2 58.3 5I.7
Work, below x m. 10. 5 89. 5 10.0 90. 0 Ilr 88.9
Work, below 5 m 7 98. 3 2.4 97.6 33 96. 7
Total work of sun and wind.............0..000006 cece eee 1,929 g. cm. 2,446 g. cm. 2,874 2. cm.
PLANKTON.
The fresh-water organisms which constitute what is known as the plankton may be
separated into two groups, namely, (a) those forms which are large enough to be captured
readily with a regular plankton net whose straining surface is made of bolting cloth,
size No. 20 (new No. 25) and (6) those forms which are so small that they readily pass
through the meshes of this bolting cloth. The former constitutes the net plankton and
the latter may be called the nannoplankton. The latter term has been applied specifi-
cally to those organisms whose maximum diameter does not exceed 25 4; but it is pro-
posed to extend the meaning of this term to include all of the material that passes through
the meshes of the net. The terms “macroplankton” and ‘‘microplankton’’ have been
used to designate these two groups.
METHODS.
The net plankton was obtained by means of a closing net which has been fully
described in a previous paper so that it is not necessary to consider it further here (Juday,
1916). ‘The coefficient of this net is 1.2; that is, about 80 per cent of the column of water
through which it is drawn is strained. The catches from the different strata were
concentrated in the plankton bucket; the material was then transferred to 8-dram vials
and preserved in alcohol. In the enumeration the volume of the catch was reduced to
ro cm.?; after shaking thoroughly 2 cm.* were removed with a piston pipette and the
crustacea and rotifers contained therein were counted with a binocular microscope.
The number thus obtained multiplied by the factor five represents the total of such
organisms in the catch. When only a few of the larger crustacea were present, the total
number was ascertained by direct count. The smaller organisms, such as the Protozoa
and alge, were enumerated by placing 1 cm.’ of the material in a Sedgwick-Rafter cell
and ascertaining the number of the various forms in the usual manner by means of a
compound microscope.
Samples of water for a study of the nannoplankton were obtained by means of a
water bottle. ‘The minute organisms were secured from these samples by means of an
electric centrifuge having a speed of 3,600 revolutions per minute when carrying two
236 BULLETIN OF THE BUREAU OF FISHERIES.
15 cm.’ tubes of water. The sedimentation was usually completed in about six minutes.
The material was then transferred to a counting cell with a long pipette and the organ-
isms were enumerated with a compound microscope having a 16 mm. objective and a
No. 8 ocular. Many of these organisms, more especially the minute flagellates, are de-
stroyed by the various preserving agents, so that it is necessary to have the living material
for these enumerations; such counts must be made, therefore, as soon as possible after
the samples of water are obtained.
The results obtained in the various enumerations are shown in Tables 17, 18, and 21.
The figures indicate the number of individuals per cubic meter of water at the different
depths. For purposes of comparison the results obtained for net plankton on Canandai-
gua, Cayuga, and Seneca Lakes in 1910 are shown in Table 18. Observations were made
on the net plankton and nannoplankton of Green Lake, Wis., in 1918, soon after these
were made on the Finger Lakes, and these have been included in Tables 17 and 21 for
comparative purposes also.
NET PLANKTON.
Phytoplankton.—Table 17 shows that the green and blue-green alge were scarce in
the three Finger Lakes at the time of the observations in 1918. Only three forms were
present, namely, Anabaena, Microcystis, and Staurastrum. In Canandaigua Lake a
relatively small number of colonies of Microcystis was found in the upper 10 m. and
Staurastrum was noted in the ro to 40 m. stratum. In Cayuga Lake Anabaena was
obtained in the upper 5 m. and Microcystis in the upper 10m. In Seneca Lake this group
was represented only by a few colonies of Microcystis in the 10 to 15 m. stratum. A
comparison with Table 18 shows that fewer forms were present in 1918 than in 1910 and
also that the number of individuals was much smaller in the former year. The two
sets of catches on Canandaigua Lake present the most marked difference in this respect.
The net catches from Green Lake, Wis., contained a much larger algal population
than the Finger Lakes, owing to the presence of a large number of filaments of Oscil-
latoria. This form was unusually well represented in the upper 15 m., a maximum of
nearly two million filaments ver cubic meter of water being found in the o to 5 m.
stratum.
_- Inthe Finger Lakes the most abundant diatom, both in 1910 and 1918, was Aster-
ionella, while Fragilaria was second in importance both years. In Canandaigua Lake
the diatom population was substantially the same in these two years, while in Cayuga
Lake the number was much larger in the former year. In Seneca Lake, on the other
hand, the number was larger in 1918 than in 1910.
In Green Lake Asterionella was the only diatom noted, a few individuals of this
form being present in two catches.
Zooplankton.—Uroglena was fairly abundant in the upper 30 m. of Canandaigua
Lake and a few colonies of Epistylis were noted in the 5 to 10 m. stratum. In 1910
Ceratium was the most abundant protozoan in this lake; but it was not found in 1918.
In Cayuga Lake Actinosphaerium and Ceratium were about equally numerous in
1918, both being most abundant in the upper 15m. ‘The former was not found in 1910.
and the latter was much more abundant in this year than in 1918, the number reaching
more than a million and a half per cubic meter in the o to 5 m. stratum. Dinobryon
was not as abundant in 1918 as in 1910 and Mallomonas was not noted in the former
year.
FINGER LAKES OF NEW YORK. 237
In: Seneca Lake Ceratium and Dinobryon constituted the protozoan population.
A relatively small number of the latter was noted in the 5 to ro m. stratum. Ceratium
was distributed through the upper 20 m. but was most abundant in the upper 5 m.
The rotifer population was largest in Cayuga Lake and smallest in Canandaigua
Lake in 1918. In the latter lake rotifers were most numerous in the upper ro m. while
in Cayuga and Seneca Lakes the largest number was found in the upper 15 m.
The maximum number of individuals in the rotifer group was noted for Synchaeta
in Cayuga Lake, where it reached 44,700 per cubic meter of water in the 10 to 15 m.
stratum; the average number in the upper 15 m. was 35,950 individuals. This form
was not found in the other two lakes.
Polyarthra was noted in the catches from each of the three lakes in 1918, but it
was most numerous in Cayuga Lake, reaching a maximum of 21,000 individuals per
cubic: meter in the 5 to 10 m. stratum. The maximum number in this lake in 1910
was a little more than ten times as large as this.
Conochilus was also found in the catches from each of the three lakes, but it, too,
was most abundant in Cayuga Lake, reaching a maximum of 33,750 per cubic meter
in the o to 5 m. stratum.
A few individuals of Anuraea cochlearis were found in the upper water of Canan-
daigua and Seneca Lakes, but this form also was distinctly more numerous in Cayuga
Lake. The catches from Canandaigua Lake contained a few specimens of Notholca
longispina, and the material from Cayuga Lake showed the presence of a few individ-
uals of Asplanchna and Ploesoma in the upper water.
The rotifer population of Canandaigua Lake was substantially the same in 1918
as in 1910. (See Tables 17 and 18.) In Cayuga Lake Polyarthra was not nearly as
abundant in 1918 as in 1910, but the other forms were more numerous, in general, in
the former year. In Seneca Lake not so many forms were represented in 1918 as in
1910, but those that were present were more numerous, so that the total rotifer popu-
lation was somewhat greatef in the former year.
In Green Lake the rotifers were more abundant than in Canandaigua Lake, but
they were not as numerous as in Cayuga Lake; the number in the upper 20 m. was
substantially the same as that of this stratum in Seneca Lake.
Copepod nauplii were most abundant in the upper 20 m. or 30 m. of each Jake,
but they were present in the lower strata also. A larger number was found in Seneca
Lake than in the other two lakes and the number in Seneca Lake was larger in 1918 than
in 1910. In the other two lakes they were more numerous in the latter than in the
former year. ‘They were more abundant in Green Lake than in any of the Finger Lakes.
Three genera of copepods were represented in the net catches from each of the
three Finger Lakes, namely, Cyclops, Diaptomus, and Limnocalanus; while a fourth,
Epischura, appeared in the 5 to 10 m. stratum of Canandaigua Lake. By far the greater
portion of the copepod population consisted of Cyclops and Diaptomus, the former
being numerically greater than the latter in each of the lakes. Both of these forms
were more abundant in Seneca Lake than in either of the other Finger Lakes. In the
former the maximum number of Cyclops was 25,100 per cubic meter in the o to 5 m.
stratum, with an average number of 21,460 in the upper 15 m. The maximum number
of Diaptomus was 9,810 per cubic meter in the 15 to 20 m. stratum of Seneca Lake.
Limnocalanus was present in the catches from each of the three Finger Lakes, but was
confined to the deeper water.
238 BULLETIN OF THE BUREAU OF FISHERIES.
In Canandaigua Lake the Copepoda were more numerous in 1910 than in 1918,
but the reverse was true of the other two lakes. ;
The number of Diaptomus was larger in the upper strata of Green Lake than in
any of the Finger Lakes, but Cyclops reached a larger number than in Seneca Lake
only in the o to 5 m. stratum.
The Cladocera consisted of representatives of Sida, Diaphanosoma, Daphnia,
Ceriodaphnia, and Bosmina. Bosmina was the most abundant form, and it was present
in the water of Cayuga and Seneca Lakes in much larger numbers than in Canandaigua
Lake. The maximum number obtained was 19,100 per cubic meter of water in the
10 to 15 m. stratum of Seneca Lake. The average number in the upper 15 m. of Cayuga
and Seneca Lakes was 12,770 and 11,200 individuals per cubic meter, respectively.
' Ceriodaphnia was found only in the 5 to 10 m. stratum of Cayuga Lake and Sida
only in the o to 5 m. stratum of this lake. Diaphanosoma was noted only in the o to 5
m. stratum of Canandaigua Lake.
Daphnia retrocurva was obtained from the upper 30 m. of Canandaigua Lake, and
a few young of this species were present in the 5 to 15 m. stratum of Cayuga Lake and
in the 10 to 15 m. stratum of Seneca Lake.
In Canandaigua and Cayuga Lakes Cladocera were more abundant in 1910 than
in 1918, while the reverse was true of Seneca Lake.
The Cladocera were more numerous in Green Lake than in Canandaigua Lake, but
they did not reach as large a number as in Cayuga and Seneca Lakes.
The numerical data serve to give a reasonably accurate notion of the plankton popu-
lation of these lakes, but such data alone do not give an adequate idea of the relative
value of the various forms as a source of food for other organisms. When they are
combined with data relating to the weights of the different organisms their value is
very greatly enhanced. By means of small platinum crucibles and a sensitive assayer’s
balance the weights of the more important crustacean constituents of the plankton
were obtained and the results of such determinations are shown in Table 19. Such
data have also been secured for various constituents of the plankton of Wisconsin lakes
and where such results were not obtained for some of the forms from the Finger Lakes,
those from the former lakes have been used in computing the data shown in Table 20.
The dry weight was obtained for all of the material and the wet weight as well for
a few of the forms; after taking the dry weight the material was ignited in an electric
furnace for the purpose of ascertaining the percentages of organic and inorganic matter.
In computing the data for crustacea in Table 20 the number of crustacea per cubic
meter of water in astratum was multiplied by the volume of that stratum and the total
for the lake was ascertained by adding the numbers in the various strata. This total
multiplied by the weight of the particular organism under consideration gave the
amount of such material in the entire lake; this quantity divided by the surface area
of the lake gave the weight per unit area, which is expressed in the table in kilograms
and pounds per square kilometer and acre, respectively.
The amount of material per unit of surface is larger in the deep water than in the
shallow water, but the sides of these lakes have such steep slopes that the results would
not be altered very materially by taking this fact into consideration. Also it must
be borne in mind that these figures are based upon a single set of catches in each lake
FINGER LAKES OF NEW YORK. 239
and that a more extended series of observations might have yielded somewhat different
results. The data in hand, however, are sufficient for a fairly good estimate. No
organisms were weighed in 1910, but for purposes of comparison the data obtained in
1918 have been applied to the numerical results of the former year.
In 1910 Canandaigua Lake possessed the largest amount of crustacean material,
having about 2,579 kg./kim.? of surface, while Seneca Lake was second with slightly
more than three-quarters of this amount. Cayuga Lake, however, was less than 10 per
cent below Seneca Lake. The greater portion of the material consisted of copepods
in Canandaigua and Seneca Lakes; in the former they comprised about 67 per cent of
the total amount of crustacean material and in the latter about 79 per cent.
In Cayuga Lake, however, about 72 per cent of the material consisted of the clado-
ceran Bosmina. Of the cladoceran material in Canandaigua Lake in 1910, Daphnia
retrocurva furnished about 30 times as much as Bosmina and about 4 times as much as
Diaphanosoma. Bosmina was the only representative of this group that was obtained
from the other two Finger Lakes in 1910. Among the copepods Diaptomus was the
most important form in this year and Cyclops ranked second.
In 1918 Canandaigua Lake possessed only about a third as much crustacean material
as in 1910 and Cayuga Lake only about four-fifths as much. Seneca Lake, on the other
hand, showed a much larger amount in the former year, the amount exceeding that of
the latter year by about 62 per cent. ‘Thus Seneca Lake in 1918 had almost four times
as much crustacean material as Canandaigua Lake and more than twice as much as
Cayuga Lake. Daphnia retrocurva was again the chief cladoceran element in Canan-
daigua Lake, but it was greatly exceeded by Bosmina in the other two lakes. Diaptomus
furnished the largest amount of crustacean material in Canandaigua and Cayuga Lakes,
but Cyclops was the chief constituent in Seneca Lake.
Green Lake, Wis., possessed a larger amount of crustacean material in 1918 than
was found in the three Finger Lakes either in 1918 or in r910.. It was almost 10 per
cent greater than that of Seneca Lake in 1918, which was the maximum for the three
Finger Lakes. ‘The copepods formed a much larger proportion of the material in Green
Lake than in the Finger Lakes, because the Cladocera constituted a little less than 3
per cent of the total in this lake. Nearly two-thirds of the entire amount of crustacean
material in Green Lake was furnished by Diaptomus.
Table 19 shows that the ash constitutes from 13 to 19 per cent of the dry weight
of the crustacea of the Finger Lakes. In addition, also, it has been found that plankton
crustacea contain from 4 to 9 per cent of chitin, which has no food value. In round
numbers, then, it may be said that about 20 per cent of the dry weight of the plankton
crustacea from the Finger Lakes consists of ash and chitin, while about 80 per cent
may be regarded as actual food material. In the living state from 85 to 90 per cent
of the mass of these organisms consists of water, so that the live weight would be ap-
proximately 10 times as large as the figures given in the dry weight column of Table
20, page 248.
In the crustacea from Green Lake the ash was much smaller, averaging somewhat
less than 6 per cent; adding to this about 6 per cent for chitin leaves about 88 per cent
of food material. The latter figure is higher than that for the Finger Lakes, which
is due to the higher percentage of ash in the material from these lakes.
240 BULLETIN OF THE BUREAU OF FISHERIES.
No determinations of the weight of the rotifers were made for the Finger Lakes,
but such results have been obtained for three species from Wisconsin lakes, namely,
Asplanchna brightwellit, Brachionus pala, and Conochilus volvox. ‘The weight of ‘these
forms has been used as a basis for estimating the weight of the various rotifers in the
plankton catches from the three Finger Lakes, N. Y., and from Green Lake, Wis. The
computations are based on the relative volumes of the different forms, so that they
are to be regarded as estimates and not the results of actual weighings. These estimates
are shown in Table 20.
Cayuga Lake had the largest amount of rotifer material both in 1910 and in 1918,
with 111 kg./km.? (1 pound per acre) in the former year and 145 kg. (1.3 pounds)
in the latter year. It had 43% times as much as Seneca Lake in 1910 and about 3%
times as much in 1918; it had 12 times as much as Canandaigua Lake in 1910 and
about 52 times as much in r918. Green Lake had just half as much rotifer material
as Cayuga Lake in 1918.
In the rotifers that have been weighed the ash averaged about 7.4 per cent of the
dry weight, ranging from a minimum of a little Jess than 6 per cent to a maximum
of a little more than 9 per cent. Thus between go and 95 per cent of the dry weight
of these rotifers may be regarded as organic matter, but what proportion of this is
indigestible has not been determined. Also it has been found that from 90 to 94 per
cent of the living rotifer consists of water, so that the weight of the live organisms
would be somewhat more than 10 times as large as the figures given in the table.
The relative importance of the crustacea and the rotifers as sources of organic
matter which will serve as food for other organisms is shown in Table 20. In Canan-
daigua Lake, which had a very small rotifer population, the ratio of the organic matter
in the rotifers to that in the crustacea was 1:256 in 1910 and 1:292 in 1918. Owing to
the very much larger rotifer population in Cayuga Lake the ratio there was 1:13 in
1910 and about 1:9 in 1918. In Seneca Lake these ratios were about 1:70 each year.
In Green Lake the crustacea contributed about 49 times as much dry organic matter
as the rotifers in 1918.
The dry weight of the crustacea and rotifers combined amounted to 2,588 kg./km.?
(23 pounds per acre) in Canandaigua Lake in 1910; this was the maximum quantity
found in the three Finger Lakes in that year. The minimum amount was noted for
Cayuga Lake, namely, 1,945 kg. (17.3 pounds). (See Table 20, p. 248.)
In 1918 the maximum for these two groups of organisms was found in Seneca Lake
and it amounted to 3,267 kg. of dry matter per square kilometer (29.1 pounds per
acre). Canandaigua Lake possessed the minimum amount for this year, namely, about
852 kg. (7.6 pounds). This was only about one-third as much as this lake yielded
in 1910.
In Green Lake these two groups of plankton animals yielded about 3,458 kg. of
dry matter per square kilometer of surface (31.6 pounds per acre) which was about
10 per cent larger than the amount in Seneca Lake in 1918.
No attempt was made to determine the weight of the alge in the net plankton,
but as the catches appeared under the microscope by far the greater portion of the mate-
rial consisted of rotifers and crustacea, probably three-quarters of it or more. Adding
25 or even 50 per cent to the above figures would still leave a relatively small amount
FINGER LAKES OF NEW YORK. 241
of material per unit of surface. In general, these lakes may be regarded as poor in net
plankton, the usual characteristic of lakes as large and as deep as these.
‘The figures given in the various tables represent the amount of material that is
present on a particular date—that is, the standing crop at that time—but they do not
indicate the quantity of such material that is produced annually. Production and
destruction are processes which continue throughout the year, so that it is a very difficult
problem to ascertain just how much net plankton is produced annually by a lake.
NANNOPLANKTON.
The nannoplankton includes the various forms of plants and animals which are so
small that they readily pass through the meshes of the bolting-cloth strainer in the plank-
ton net and are lost. These small organisms are easily obtained with a centrifuge.
The results obtained in these enumerations on the three Finger Lakes of New York
and on Green Lake, Wis., are shown in Table 21.
The Protozoa were represented by rhizopods, flagellates, and ciliates. The rhizo-
pods consisted of Amoeba and some other forms which were not definitely identified.
A minute Monas-like form was the most numerous flagellate found, while Cryptomonas
was present in considerable numbers in Canandaigua and Seneca Lakes. A disk-shaped
flagellate was noted in the upper strata of Cayuga and Green Lakes. Synura was also
present in the surface stratum of Canandaigua Lake.
The only representative of the ciliates was Halteria. It appeared in the upper
strata of Canandaigua and Cayuga Lakes.
The green and blue-green alge consisted of Scenedesmus, Oocystis, and Aphanocapsa.
A colonial form composed of very minute cells, 25 to 100 or more, embedded in a gelat-
inous matrix, has been referred to the genus Aphanocapsa. It appears to be widely
distributed, geographically, since it has been found in all of the Wisconsin lakes from
which nannoplankton has been obtained, and also in the three Finger Lakes. This alga
has usually been fairly evenly distributed throughout the entire depth of the various
lakes. This phytoplankton and the monads constitute the most common elements,
numerically, of the nannoplankton.
The water bacteria belong to this group of plankton organisms, but they were not
taken into consideration in these investigations.
No attempt was made to determine the amount of nannoplankton by weight, but
some results that have been obtained'on Lake Mendota, Wis., will serve as a basis for
making a rough estimate for the Finger Lakes. The studies on Lake Mendota covered
a period of more than two years and they consisted of both gravimetric and numerical
determinations. ‘The dry organic matter of the nannoplankton varied from a mini-
mum of approximately 0.8 gr. to a maximum of 3.1 gr. per cubic meter of water. The
numerical determinations which correspond most closely to those of the Finger Lakes
average about 1.0 gr. of dry organic matter per cubic meter of water, so that this figure
may be taken as a basis for estimating the amount of nannoplankton material in the
latter. The results of this estimation are shown in Table 22, and also the results for
total plankton. In the latter it has been assumed that the crustacea and rotifers
furnished 75 per cent of the organic matter of the net plankton. Green Lake has not
242 BULLETIN OF THE BUREAU OF FISHERIES.
been included in this table because its net plankton contained a larger percentage of
vegetable material.
These computations seem to indicate that the nannoplankton of Seneca Lake
contained somewhat more than 234 times as much dry organic matter as the net
plankton, while in Canandaigua Lake the former was more than 4 times as great as
the latter. These differences are of the same magnitude as those that have been
obtained on Lake Mendota in midsummer. On an average, also, it may be considered
that this material weighs at least 10 times as much in the living state, since most of
these organisms, when alive, are made up of 90 per cent or more of water.
The results shown in this table represent only a single phase of the annual cycle,
and hence they do not give any indication of the yearly production of such material.
This latter question involves the actual turnover in stock each year and includes the
various relations of the organisms to each other and to their environment; the chief
phases of this question are the rate of reproduction of the various forms at different
seasons of the year, and the relations of the consumers and their foods. The whole
problem is very complex and would require an extended investigation for an adequate
solution.
These quantities of dry organic matter in the total plankton of the Finger Lakes
are very much smaller than those that have been obtained for Lake Mendota, Wis., in
midsummer. In this latter lake the average amount for the month of July in 1915
and in 1916 was 40,630 kg./km.? of surface (362.4 pounds per acre) in that portion of
the lake having a depth of 20 m. or more; the average for August of these same years
was 31,560 kg. (281.5 pounds). The average for Lake Mendota in July is more than
three times the amount shown in this table for Seneca Lake and more than eight times
that for Canandaigua Lake.
Comparisons have been made between the productivity of the land and of the
water, but such comparisons have been based upon the production of beef on the one
hand and of fish, or oysters, or other edible aquatic forms on the other hand. These
materials are what may be termed the “finished products,” and statistics relating to
them give no idea of the relative amounts of food required or available for their pro-
duction. This is accounted for by the fact that data concerning the quantity of food
available, either directly or indirectly, for aquatic organisms have been for the most
part wholly lacking and at best only fragmentary in character.
The quantitative results given above for the plankton, however, enable one to
make direct comparisons with the land on material which is not an end product. The
grass produced by a pasture is probably the best land crop for such a comparison, be-
cause it is less subject to artificial conditions resulting from cultivation than the grain
crops. Henry (1898, p. 180) cites an experiment in which a pasture consisting of blue
grass and white clover yielded 165,827 kg. of dry organic matter per square kilometer
(1,477 pounds per acre) between May 1 and October 15. This quantity is just a little
more than four times the average amount of organic matter maintained by the deeper
water of Lake Mendota in July. In other words, a fourfold turnover in the stock of
plankton maintained by Lake Mendota during this month would have yielded as much
organic material annually as the pasture in the above experiment. During the vernal
and autumnal maxima of the plankton the difference is distinctly less than fourfold.
The roots were not included in this yield of grass and, taking them into consideration,
FINGER LAKES OF NEW YORK. 243
we may say that the average difference for the year would be substantially fourfold.
The differences are much greater in the Finger Lakes, ranging from about fourteenfold
in Seneca Lake to almost thirty-fivefold in Canandaigua lake. (See Table 22, p. 250.)
The dry organic matter of the grass was made up of about 25.4 per cent crude
protein, 4.7 per cent ether extract, while the remainder consisted of carbohydrates.
The plankton of Lake Mendota, however, was distinctly richer in nitrogenous material
and in fats; the average for the crude protein was 45.1 per cent of the dry organic
matter and for the ether extract 8 per cent.
Attention should also be called to the fact that the plankton does not represent
all of the food material that is produced by a lake; the bottom fauna and the large
aquatic plants growing in the shallower water make notable contributions to this mate-
rial. The quantity of plankton is not as large per unit of surface in the shallower water
as it is in the deeper water, but the larger bottom population in the former region tends
to counterbalance this deficiency when the question of the total production is con-
sidered.
PLANKTON TABLES.
Tables 17 and 18 show the vertical distribution of the various organisms consti-
tuting the net plankton, giving the number of individuals per cubic meter of water in
the different strata. The members grouped in the different columns are indicated as
follows:
CLapocERA.—B=Bosmina, C=Ceriodaphnia, D=Daphnia, Di=Diaphanosoma, L=Leptodora,
P=Polyphemus.
CopErrpopa.—C=Cyclops, D=Diaptomus, E=Epischura, L=Limnocalanus.
NAvpPLu.
RotirERA.—A=Asplanchna, A.a.=Anuraea aculeaia, A.c.=Anuraea cochlearis, C=Conochilus,
N=Notholca, P=Polyarthra, Pl=Ploesoma, R=Rattulus, S=Synchaeta, T=Triarthra.
Protozoa.—A=Actinosphaerium, C=Ceratium, D=Dinobryon, E=Epistylis, M=Mallomonas,
U=Uroglena, V=Vorticella.
GREEN AND BLUE-GREEN ALGAj.—An=Anabaena, Ap=Aphanocapsa, Coe=Coelosphaerium,
G=Gloeocapsa, L=Lyngbya, M=Microcystis, O=Oscillatoria, S=Staurastrum.
Diatoms.—A=Asterionella, F=Fragilaria, M=Melosira, S=Synedra, T=Tabellaria.
TaBLE 17.—ANALYSIS OF NET PLANKTON, 1918.
CANANDAIGUA LAKE, JULY 27, 1918.
mn : Green and.
Depth in meters. Cladocera. | Copepoda.| Nauplii. | Rotifera. | Protozoa. blue green Diatoms,
alge.
U 13, 600 M 13,600 .F 6,800
5 arctsraeverersens E 130
BATOsisi3 disisiae dd SAMARAS Ba EROS ad sc 2,485 U 13,600
cho ae 10 rd 330 city 7, com s 10, 200 ¥ gace.
20m 30LS. as 14 Semebnincecesan en ariemepieds os 65 U 20, 400 S 3,400
Labsoniee a
Ec eT. | Cis i Soe aes : :
100
HOrOOsshisnriadraadanr ps cecueada: aa deien ss
244
BULLETIN OF THE BUREAU OF FISHERIES.
TABLE 17.—ANALYSIS OF Net PLANKTON, 1918—Continued.
CAYUGA LAKE, JULY 30, rorx8.
Green and
Depth in meters, Cladocera. | Copepoda.| Nauplii. | Rotifera. | Protozoa. plas treed Diatoms.
alge.
B 10, 200 Crp 2008 | ea asanceienes ASOTG: Ix acess ceiesnriterss [termes arecaatsieaea ses Avie wnaeevdes
C5 Bi SBO: lhe ic adevetens ese Unenncask hs woeesonen sasnadeetan ocd BENS
C 33,750 | A 108,800 | An 13,600 A 13; 600
P17, 400 | C129, 200 M 6, 800 F 20, 400
Pl. 150 |.. P :
S$ 25,770 |..
AAT; 180: | sense a haces
A... 4, 580 A 34,000 |............ A 27, 200
C 17, 265 102,000 M 6, 800 F 27,200
SENECA LAKE, AUG. 1, 1918.
C 25, 100
L
POOntA.vO
BEES3
Lal
w
FINGER LAKES OF NEW YORK. 245
TaBLE 17.—ANALYSIS OF NET PLANKTON, 1918—Continued.
GREEN LAKE, WIS., AUG. 20, 1918.
, Green and
Depth in meters. . Cladocera. | Copepoda. | Nauplii. | Rotifera. | Protozoa. aria Diatoms.
algee.
B 1,570 © a6, 868 Ih oy caverns C 5,100 C 20,400 | An 27,200
OS ba icioa exis cuartone yale ndeminacis wameinienee D 302 D 33,225 87,900 N 3, rfo D 6,800 |O 1,822,400 |...
C8, 765 |... . cece ee
eorith Vin iguidisist.ye talento 48 ame ae ) D 21,715
' P 2, 485 |..
. |A.e. 10,725 |..
7 TABLE 18.—ANALYSIS OF NET PLANKTON, IgI0.
CANANDAIGUA LAKE, AUG. 20, 1910.
.
Green and /
Depth in meters. Cladocera, | Copepoda. | Nauplii. Rotifera, | Protozoa, aiearet Diatoms.
algae.
C 4, g00 18, 500
D 14, 200 |. A
Coe 3, 800 ae
246
BULLETIN OF THE BUREAU OF FISHERIES.
TaBLE 18.—ANALYSIS OF NET PLANKTON, rg10o—Continued.
CAYUGA LAKE, AUG. 12, r9r0.
Green and :
Depth in meters. Cladocera. | Copepoda. | Nauplii. | Rotifera. | Protozoa. Bing aieett Diatoms.
alge.
A 2, 105, 300
F 812, yoo
T 54, 200
‘A’ 3, 204, 000
928, 800
C 665, 600
D 15, 500
V 260
T 108, 300
A 2, 182, 700
F 944, 300
T 123, 800
M 3, 800
T 27,000
F 7, 700
T 7, 700
9, 600
T 15, 200
An 1,900
M 7,700
A 310,700
F 5,800
FINGER LAKES OF NEW YORK. 247
TABLE 18.—ANALYSIS oF NET PLANKTON, rg9r0o—Continued.
SENECA LAKE, AUG. 2, 19:0—Continued.
: : Green and
Depth in meters. Cladocera. | Copepoda.| Nauplii. | Rotifera. | Protozoa. | blue-green| Diatoms.
alge.
00.
M 9,600
TABLE 19.—WEIGHTS OF DIFFERENT Forms oF CRUSTACEA FROM THREE FINGER LAKES, N. Y.,
AND FROM GREEN LAKE, WIS.
CANANDAIGUA LAKE.
: Wet weight in Dry weight in
Organism: milligrams. milligrams.
Per cent.| Per cent. Remarks.
= of water.| of ash. *
Name. No. | Total. Each, Total. Each.
Daphnia ac. sewaivcantaaiasca oie dase -25 | 0.0230 |.......... 22.40 | Adults.
Diaptomus.................665 id TA Bh 64 BOOB | aypionsicesarers iets 13-4 : f
Limnocalanus it 14 HOSAS Lseueniqaee niece 5.45 | Mixed sizes.
MY Sissi 255 ps cretmagnias os se ous one -20 | 1T00 [.....-.60. 12. 02 _ Do.
BOSMING, ¢ o. ce caw sass eg conewie on on gee +90 200296 |.........- 31.11 | Chiefly adults.
Polyphemus...........56 00sec eee eee eee -78 SOLOI. | evra Ya osx 21.80 | Mixed sizes.
BOA. laidscsiy eked awe oe ANS 1.89 | 0.0047 |.......... 12.70 | Chiefly adults.
250 saicxcussdes vigrsielfsts Shel ans Gina 12-75 SORIO: fi sae srrneis 3-78 | Large.
532 23- 46 0. 0441 2-34 +0044 90. 00 15-38 | Chiefly adults.
SENECA LAKE
Diaptomus........... 05 eee eee ern ee 200 12.16 0. 0608 1.26 | 0.0063 89. 64 15. 08
Limnocalanus ..| 108 37°77 +3497 5-14 +0476 86. 40 6.61 5 7
Daphitia....... 26. ceeds bance eee n een es GOO. | vvattcaernes seclllereadnes teeine 2.56 POO§T |. sa egesiees 15-62 | Mixed sizes.
GREEN LAKE.
Diaptomus. ..........0 66. c eee e ee ene BOO Neserey ca caveats aiceshaveicness 3:69 | 0.0074 |.......6.. 5.15 | Chiefly adults.
Limnocalanus G50 lscea os oxste| soreness 17.88 2O325> |basiivaieynrans ofa 3°75
248 BULLETIN OF THE BUREAU OF FISHERIES.
TABLE 20.—DRY WEIGHT AND ORGANIC MaTTrER OF PLANKTON CRUSTACEA AND RotImrERSIN THREE
Fincer Lakes, N. Y., AND IN GREEN LAKE, WIS.
CANANDAIGUA LAKE.
I9Io 1918
Dry weight. ‘Organic matter. Dry weight. Organic matter.
Organism.
Kilograms Kilograms Kilograms Kilograms
per square | Pounds | per square | Pounds | per square} Pounds | per square| Pounds
kilometer | per acre. | kilometer | per acre. | kilometer | per acre. | kilometer | per acre.
of surface. of surface. of surface. of surface.
15. 80 O14 27.70 0. 25 19. 10 O17
517.70 4. 61 94. 70 84 73. 50 65
154. 70 1. 38 16. 30 +14 15. 30 -13
182. 60 1. 62 38. 50 +34 33. 60 +30
I, 094. 15 9.74 385. 10 3-43 333-50 3.00
158. 80 I. 42 271. 20 2.41 256. 40 2. 28
afeaieneieangaesg: > fies isabstane eee 10. 10 .o9 9. 50 +08
72. 21 64 5.30 +05 4.60 +04
2,195.96 19. 55 848. 90 7-55 745- 5° 6.65
8. 56 O74 2.76 024 2.55 022
CAYUGA LAKE.
Plankton crustacea
Bosmina sciatic “apd oiatayrsepretsasione 263 200 f00eI I, 320. 25 11.75 909. 52 8.10 459. 43 4.09 316. 57 2. 82
14. 38 «13 II. 20 .I0
374. 61 3. 33 327. 00 2.90
519. 00 4. 60 449. 40 4.00
36. 13 «32 34.70 28
68. 00 -60 59. 20 +52
Total... cic cece. ddsdabeyeleraie SiGe 1, 834. 14 16. 32 1, 356. OL 12.07 I, 471.55 13. 07 1, 198, 07 Io. 62
RROGHETS s 62: f5-d ised dee aeadrnsiev 483 T10. 91 I.00 102. 78 +92 145. 24 1.30 134. 50 I. 20
SENECA LAKE.
421.00 3-75 290. 00 2.60
16. 70 -14 13. 00 .I0
I, 491. 60 13-30 1, 262. 00 II. 30
I, 192. 00 10. 60 I, O13. 20 9. 00
69. 00 . 61 64. 40 +57
35-70 «32 30. 30 27
Totalasi ci iv dase pctmiuiaanan: 1, 992. 04 17. 72 1, 625. Bo 14. 45 3, 226. 00 28.72 2,672.90 23. 84
Rotilersi.wiwssos ah owe diaumaeawnes 24. 58 22 22. 78 20 41. 28 +37 38. 22 +34
GREEN LAKE.
24.00 oO. 21 22.44 oO. 20
59-35 +53 50. 00 +44
20. 60 «18 19. 30 +17
809. 00 7.20 760. 50 6. 80
2,034. 31 18, 10 I, 929. 54 17.16
104. 20 +92 100. 30 - 88
424. 00 3:77 400. 68 3-55
Teta) chops cebu se Savivnestet teat avacecal Wea mens yrs see allan ecg neha al San dse Besrendas | eradoeansictinate st 3,475. 46 30. 91 3, 282. 76 29. 20
PROtHOTS ss ciancealers iets ws wremin Sictarcapretnare ale cabintameatelecs ate Lareiaio® Vie diced lop etiemmigranonces | monieasineyen 92.70 65 67. 32 . 60
FINGER LAKES OF NEW YORK.
249
Table 21 shows the vertical distribution of the organisms 1n the nannoplankton,
The forms are as follows:
indicating the number of individuals per cubic meter of water at the different depths.
Protozoa—A=Amoeba, C=Cryptomonas, F=unidentified asymmetrical flagellate, H=Halteria,
M=monads,. R=unidentified rhizopods, S=Synura,
GREEN AND BLUE-GREEN ALGai—Ap=Aphanocapsa, Oo=Oocystis, Sc=Scenedesmus
Diatoms—N=Navicula, S=Stephanodiscus, Sy=Synedra.
TABLE 21.—ANALYSIS OF NANNOPLANKTON.
CANANDAIGUA LAKE, JULY 28, r918.
* Depth in Green and blue- . Depth in Green and blue- HH
meters. Protozoa. green alge. Diatoms. meters. Protozoa. green alga. Diatoms.
or eee |
C 31, 242,000 | Ap 135,382,000 | * S 15,621, 000 36 e { C 5,207,000 | AP 98,933,000 N 10, 414, 000
Tn - See 52,000, C00 Carre | aac as M 10,414,000 |... ..... ee eee eees ee naoc ieee
VOTH. SSB 9 DOO OOO Wess aso siniscaiieseie eyoiene) siartiemrainiere piste Oy 414, 000
oe “Ap 182, 245,000 S 36, 449, 000 || 30---+ +++ M 31,242,000 | Ap 130,175,000 K{ S 8830 oe
Bees aw Hl 5,200,000 |. ........ 00.05 Sy 10,414,000 C 15,621,000 | Ap 135,382,000 5) 207,000
ci M 15,621,000 |....... et eee AOS ee M 15,621,000 |.......0.ecseeee | § 10,414,000
C 5,207,000 | Ap 187,452, . S 31, 242,000 C 5,207,000 | Ap 130,175,000 s 26,035,000
Biacvigaces 5;200,000 |..... a Sy 5,207,000 M 20,.484;000 | congeses vx enntechorisasawen 2 asin
Mi:90;828; 000% |e -aaniaitnresc cessiallaisaniiiciaeacin soma: [|| OSe.swrevamaveleneae sa bracnaeies AP 229, 108, 000 § 10, 414, 000
C 20,828,000 | Ap 156, 210, N ro, 414,000
WS scocivcanoms H 5; 200, 000 Sc 20, 828, 00 S 57,277,000
Mi 20;414; S001 bs dutetevastor vn conalemmeanesshen ei
CAYUGA LAKE, JULY 30, 19178.
F395) 242900" | s4 anceniss oc ananassae eres M 20,828,000 | Ap 62,484,000] $5,207,000
H_ 5,207,000 | Ap 93, 726,000 N 5, 207,000 M 26,035,000] Ap 67,691,000 |- S 5,207, coo
bosseueaeiy, Onan piaititie M 26,035,000 Sc 20, 828, 000 S 5,207, 000 M 26,035,000 | Ap 52,070,000 S 5,207, 000
R 20, 828. 15,621,000 AD 62, 484,000 |.........5 000008
z 26, 035,000 { 10,414,000 | Ap 67,691,000 S 5,207,000
Geis teen M 20, 828, c00 R 5,207,000 |........ pesplaistese #1058 nc ville pacneiankssrents
R 52,070, 000 \
C 5,207,000 | Ap 78,105,000 |............0065
Bias wieavacess M 36, 449, 000 Sc ro, 414,000 S 5,207,000
R20;8285006) |iss vidiccsscav ss saan laswsimaninsan i &
SENECA LAKE, AUG. :, 198.
C 41,656,000 | Ap 72,898, 000 S 15,621,000 C 5,207,000 | Ap 36,449,000 |........... 0.08 te
NN Osseeter sel) OM 4s) 800,000 Oo 5,207,000 Sy 5,207,006 |] 3o......... M 36,449,000 | Oo 10,414, 000 S 10, 414, 000
C 15,621,000 | Ap 161,417,000 S 15,621,000 FRG 5,207, 000) [ied nes distars cig cictonraiel|tie eee barremesiaine: ‘
Somes errs M 119,761,000 O0 10, 414,000 |.... 2. cece eee GO sss vas tis se M 20, 828,000 | Ap 62, 484, 000 S 5,207,000
5,207,000 | Ap 62,484,000 S 15,621,000 |] 75......... M 5,207,000 | Ap 72,898,000 10, 414, 000
BOR eats M 20,828,000 | Oo 15,621,000 M 15,621,000 | Ap 67,691,000 S 10, 414; 000
C 5,207,000 AP 67, 691, 000 M 10, 414, 000 AP 46, 863, 000 S 5, 207,000
M 10, 414,000 Qo 26,035,000 5) 207, 000 APD 67, 691, 000 S 5,207,000
5,207,000 | Ap 36,449, 000
M 10, 414, 000 Oo 10, 414, 000
GREEN LAKE, WIS., AUG. 20, 1918.
F 5,207,000 |... .....0.e0e eee S 5,207,000 |} ,, { M 20,828,000 | Ap 72,900,000 S 5,207,000
M 14,000 | Ap 145,800, 000 Sy 20,828,000 || ““"""""""°** 15512070008 os se Siete eaniays tall ewnere’s pintulaueiae Sm
Te F254, 008 Ramat steed sina Bic ot'| | eects ks M 5,207,000 | Ap 46,800,000 S 5, 207, 000
F 10, 414,000 | Ap 145,800, 000 S 5,207, 000 A 5,207,000 | AD 57,200, 000 5) 207,000
AO ria eS S86 R 5,207,000 |........e.0e wees] S¥ 5; 207,000
M 10, 414,000 |.......-00.ee ee eel, Sy_15, 621,000 [ 5) 207, iiss 207,
15,621,000 | ADP 130, 200, 000 S 5,207,000 || 50......... [5,207,000 | Ap 67, 700, IO) 414,000
M 26,035,000 |.......... eee noes Sy_15, 621,000 || 65......... M 5,207,000 | Ap 62,500, 000 S 5,207,000
M 10, 414, 000 AD 52,070,000 $y207,000 ff fa ee eee eee eee eeehi omens sulearanreea Sy 5,207,000
250 BULLETIN OF THE BUREAU OF FISHERIES.
TABLE 22.—ESTIMATES FOR QUANTITY OF NANNOPLANKTON AND TOTAL PLANKTON IN THREE FINGER
LAKES IN 1918.
[Norx.—Total plankton equals net plankton plus nannoplankton. Quantities are shown in kilograms of dry organic material
per square kilometer of surface and pounds per acre. Living material would weigh about 10 times as much as is indicated
in the table.)
Nannoplankton. Total plankton.
Lake. ‘ ; r “ft
Kilograms Pounds Kilograms Pounds
per square | or acre. | Per sauare | oor acre
kilometer. kilometer.
3, 877.3 34.5 4, 809. 2 42.8
5, 450.0 48.5 6, 947.5 61.6
8, 859. 4. 78.8 12, 200. 5 108. 6
BOTTOM FAUNA.
Samples of the bottom at different depths were obtained in the three Finger Lakes
and also in Green Lake by means of an Ekman dredge. ‘This mud was sifted through
a fine meshed net and the organisms found therein were enumerated. The dry weight
and the ash of four of these bottom forms were ascertained. ‘The results of these dredge
hauls are shown in Table 23. The observations were far too few in number to give
anything more than a fragmentary idea of the density of the bottom fauna, since only
two hauls each were made in Canandaigua and Cayuga Lakes and but four in Seneca
Lake; in addition to this they were taken only in the deeper water. Hundreds, or
better still, thousands of observations, covering the bottom of each lake in various places
from the shore line to the greatest depths and extending through the different seasons
of the year, would be necessary to give an adequate idea of the character and abun-
dance of their bottom fauna.
Only four forms have been included in the table because they constituted by far the
greater portion of the material obtained. A few nematodes and an occasional estracod
and bivalve mollusk were noted in the shallower depths, but they were not present in
sufficient numbers to obtain their weights.
A few larve of Protenthes were obtained in the 32 m. haul in Seneca Lake and in
the 45 m. haul in Green Lake, but these were the only instances in which this larva
was noted.
Chironomid larvee were found in all of the hauls except the one made at 32 m. in
Seneca Lake. They were most abundant in Cayuga Lake, where they constituted by
far the most numerous form at a depth of 113 m. In the other three lakes, however,
they formed only a minor element of the bottom population, both in numbers and
in bulk. Earlier in the season they were probably more numerous, because many had
undoubtedly transformed to the adult stage by the time these observations were made.
In Canandaigua and Seneca Lakes the relict amphipod Pontoporeia was second in
importance, while it was third in Cayuga Lake and first in Green Lake. It was most
abundant at a depth of 45 m. in Green Lake, where it furnished the largest amount of
dry organic material that was found in any of the hauls, namely, about 8,214 kg./km.?,
or nearly 75 pounds per acre.
Oligocheta were found in all except one haul; that is, the one at 34 m. in Cayuga
Lake. In half of the hauls they furnished the greater portion of the organic material.
FINGER LAKES OF NEW YORK 251
~The largest amount was obtained at 32 m. in Seneca Lake, where it reached 1,693 kg.
of dry material per square kilometer, or a little more than 1 5 pounds per acre.
The deepest haul in Cayuga Lake yielded a larger amount of organic matter than
the deepest haul in any of the other lakes, while the one at 34 m. was the poorest of all,
due most probably to the fact that it was made on a very steep slope. Green Lake
showed the second largest amount of material in its deepest water and Canandaigua
Lake was third. In Seneca Lake the amount at 110 m. was only about three-quarters
as great as at 172 m. In general, it appears that the bottom fauna in the deeper water
of Green Lake yields a larger amount of dry organic matter per unit area than these
three Finger Lakes. :
TABLE 23.—NUMBER OF INDIVIDUALS AND WEIGHT OF Bottom Fauna OBTAINED AT DIFFERENT
DEPTHS IN THREE FINGER LAKES, N. Y., AND IN GREEN LAKE, WIS., IN 1918.
CANANDAIGUA LAKE, JULY 28, 1918.
Number Dry weight. Organic matter.
Depth in ‘ per
meters Organism. ae: teever of Kilograms | Pounds | Kilograms | Pounds
bottom, | Per sauare per per square per
kilometer. | acre. | kilometer. | acre.
(Chironomus 800 219.2 1.95 155.0 1.38
BOL cies a bd Pontoporeia... f 977 469.0 4017 352-0 3-13
Oligochaeta. .. 1,420 522-9 4-65 459-1 4.08
(Chironomus... 45 12.0 XI 8.5 +07
Di cre wyeie Sea Pontoporeia... ‘ 844 405-1 3-60 303-8 2.70
OM OCHA ene. sjs'eo dis csi ndereisesiors: ive aunrahaceieseierd ai ge wveigceidoandiage as tbe don 890 326.8 aor 286.9 2.55
CAYUGA LAKE, JULY 30, 1918.
133 36-4 +33 25-7 +23
178 85.4 +76 64.0 -57
3, 863 1,058.5 9. 42 784-4 6.66
710 340.8 3-03 255.6 2.24
1,288 474-0 4-22 416.2 3-70
4 SENECA LAKE, AUG. 4, 1918.
Protenthes ..cijceieac's s itenauavs wa cat saanaiaieis sanmware aes ee gia -28 28.8 26
Aierss ak bee Trectes: 532-8 4:74 399-6 3-55
Oligochaeta... 1,928.0 17.16 1,692.8 15.07
BTocstke cas Chironomus... 158.0 1.40 IIl.7 99
Pontoporeia . 405-1 3-60 303.8 2.70
Oligochaeta. 489-4 4°35 429-7 3-84
Chironomus. 120.6 1.07 85.3 76
p> (- aS Pontoporeia. 170.4 1.54 127.8 1.14
Oligochaeta. 147-2 1.31 149.2 1-15
(Chironomus. 12.0 eI 8&5 °7
DID uiiaivined Pontoporeia. 63-8 57 47-8 “44
Oli aeta... 473-2 4.ar 41s-5 3-76
‘Chironomus 27-7 +25 26.6 +24
Protenthes.... 10. 5 +09 7 ot
AS seas: ie > Pontoporeia... 9)910-0 88. 26 8,213.6 74-93
Oligochaeta... 4 4535 464.0 4.13
(Chironomus. .. 181.3 1. 6r 374.0 1.5!
66 Pontoporeia.... 661.0 5-90 561-2 5+ Ot
Pie a Oligochaeta,........0.eceeeee eens 542-2 4.83 515-1 458
252 BULLETIN OF THE BUREAU OF FISHERIES.
LITERATURE CITED.
Brrce, Epwarp A.
191s. The heat budgets of American and European Lakes. ‘Transactions, Wisconsin Academy
of Sciences, Arts, and Letters, Vol. XVIII, pp. 1-47. Madison.
1916. The work of the wind in warming a lake. Ibid., pp. 341-391.
1921. Limmnological apparatus. Ibid., Vol. XX (now in press).
Birrce, Epwarp A., and CHANCEY JUDAY.
1914. A limnological study of the Finger Lakes of New York. Bulletin, U. S. Bureau of Fish-
eries, 1912, Vol.X XXII, pp. 525-609. Washington.
HAMBERG, AXEL.
1g11. Dichteunterschiede und Temperaturverteilung hauptsichlich der Binnenseen. Peter-
manns geographische Mitteilungen, Bd. 57, Pp. 306-312. Gotha.
Henry, W. A.
1898. Feeds and feeding. 657 pp. Published by the author, Madison, Wis.
HuitFeLp-Kass, H
1905. Temperaturmessungen in dem See Mjésen und in drei anderen tiefen Norwegischen Seen.
Archiv for Mathematik og Naturvidenskab, Bd. XXVII, No. z, pp. 1-6. Kristiania.
Jupay, CHANCEY.
1916. Limnological apparatus. Transactions, Wisconsin Academy of Sciences, Arts, and Letters,
Vol. XVIII, p. 566-592. Madison.
Scumipt, WILH.
1908. Uber die Absorption der Sonnenstrahlung im Wasser. Sitzungsberichte der kaiserlichen
Akademie der Wissenschaften, Bd. CXVII, pp. 237-253. Wien.
&
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