Reprinted from LIMNOLOGY AND OCEANOGRAPHY
VOL IV, No. 2, April, 1959
Printed in U.S.A.
Seasonal Changes in Bluegill Metabolism'
DONALD E. WOHLSCHLAG
Department of Biological Sciences, Stanford University, California
AND
ROGELIO 0. JULIANO
Department of Zoology, University of the Philippines, Quezon City, P. I.
ABSTRACT
A one-year study of bluegill metabolism in a California reservoir indicated that field
determinations of oxygen uptake rates and multivariate analyses of results with respect
to weight, activity, and temperature during each season were feasible in the form,
Y, = constant ±
b2X2
b3X3,
where Y, is the expected log milligrams of oxygen consumed per hour, X, is the log weight
in grams, X2 is the swimming velocity in meters per minute, X, is the temperature in degrees centigrade, and where b1 , b2, and b3 are the respective partial regression coefficients.
By delimiting "seasons" on the basis of thermal and related limnological characteristics,
the data yield the equations:
Apr.-June
July-Aug.
Sept.-Dec.
Jan.-Feb.
Y, = —0.6954 -E 0.8036X1
Y, = —2.1951 ± 1.0621X 1
Y, = —0.9242 ± 0.8494X 1
Y, = —1.9310 ± 0.8624X 1
0.0250X 2
0.0138X2
0.0142X2
0.0427X 2
0.0069X 3
0.0567X 3
0.0198X 3
0.1153X 3
The multiple correlation coefficients for these equations are highly significant as are all
the partial regression coefficients, excepting the low spring b3 = 0.0069.
The weight relationships expressed by b1 are remarkably close to Krogh's constant of
approximately 0.85 except in the summer when the calculated higher rate may be due to
the spawning condition of the larger fish and the post-spawning condition of the smaller
fish.
There are similar relationships of respiratory rates with respect to swimming movements
over the spring, summer, and autumn seasons, but during winter it appears that relatively
higher oxygen consumption is required for comparable swimming activity.
The respiratory rates with respect to temperature appear to be of the same order during
spring and autumn when they are lower than in summer and much lower than in winter.
The high respiration-temperature regressions in winter, and possibly in summer, may be
due to excessive spontaneous activity not reflected as swimming motion at temperature
extremes.
Females during each season have higher metabolic rates than the males over the range
of temperatures and activities encountered, but the differences are not statistically significant.
Groups of fish during the spawning season have higher than average respiratory rates
than do single fish, other conditions being equal. Limited data suggest that social facilitation exists during the summer after spawning.
Variations in Felt Lake limnological conditions are considered from the standpoint of
about a 50 per cent reduction in volume from spring to autumn, the absence of a well developed littoral zone, and the rather drastic spring to autumn and winter declines in bottom
fauna and average weights of the larger fish. A comparison of the above regressions over
average spring and autumn conditions reveals that metabolic rates would be about equal,
This study was supported in part by a grant from the National Science Foundation.
The constructive criticisms offered by Dr. Shelby D. Gerking, Indiana University,
and by Dr. Austin Pritchard, Oregon State College, are gratefully acknowledged.
1
195
196
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
althoughinspringthefishgrowrapidlyandspawn,whileinautumnandwintertheylose
weight.Similarlythecalculatedwintermetabolicratesarehigheratcomparabletemperaturesthanthoseofspringorautumnduepossiblytocoldadaptation.
WhilethepotentialgrowingseasoninFeltLakewouldbeabouttwiceaslongasthat
forthenorthernportionofthenativebluegillrange,thegrowthratesareofthesameorder.
ThebiologicalproductivityofthebluegillinFeltLakeandsimilarwesternU.S.watersis
interpretedtobemuchpoorerthanineasternareasbecauseofthelongergrowingseason
withoutadequatefood(especiallybottomfauna)productionandbecausethereappearsto
benoadaptivemechanismforloweringthemetabolicrequirementsduringseasonsofpoor
foodsupplies.
INTRODUCTION
Thepurposeofthisstudyistodescribe
quantitativelyseasonalchangesinrespiratoryratesofthebluegill, Lepomis macrochirus (Centrarchidae),inrelationto
seasonallimnologicalvariationsofFeltLake,
asmallCaliforniareservoir.
Includedamongthephysiologicaland
limnologicalfactorswhichinfluencethe
respiratory(oxygenconsumption)rateare:
thedirecttemperatureeffect,effectoftemperatureacclimation,oxygenandcarbon
dioxidecontentofthewater,bodyweight,
bodyfatcontent,cruisingspeedoractivity,
recencyandamountoffeedingordegreeof
starvation,extentofsocialfacilitation,sex,
sexualdevelopmentandspawning,excitement,injury,shock,parasitism,disease,and
perhapsmanyotherfactors.Fry(1957)
hasgivenacomprehensiveaccountofthe
literaturedealingwiththeeffectsofthese
factorsonfishrespirationandmetabolism,
andWohlschlag(1957)hasnotedthatbody
weight,swimmingvelocity,andtemperature
accountedformostofthevariabilityin
oxygenconsumptionratesofanarcticwhitefish.Gerking(1954)hasemphasizedthe
importanceoffishmetabolismdatabyshowinghowmetabolismandbiologicalproductionarerelatedinanaturalenvironment.
Customarilyrespiratoryratesareexpressedaslogoxygenconsumedperhour,
andmetabolicratesareexpressedaslog
oxygenconsumedperhourperkilogramof
bodyweight,eitherintotalweightorin
proteinweightunits.Respiratoryormetabolicratesarealsoexpressedas"standard"
rateswhichapproachbasalrates,as"active"
rateswhichpertaintofishwithsustained
"maximum"swimmingvelocities,andas
"routine"orintermediaterateswhichpertaintofishexhibitingspontaneousactivity
otherthanswimming(Fry1957).Mostof
thepublisheddataonfishmetabolismrefer
todeterminationsforfishcarefullyacclimatedtocontrolledlaboratoryconditions,
althoughPritchard(1955)hasmadedeterminationsfortwosmallmarinespeciesheld
inconcretecisterns,andWohlschlag(1957)
hasmadedeterminationsonwhitefishin
theirnaturalhabitats.Thereisverylittle
informationavailabletosuggesttowhat
extentmetabolismoffishvarieswith
seasonallimnologicalconditions.
Ontheassumptionthatbluegillsintheir
naturalstatewere"acclimated"tocurrently
existinglimnologicalconditions,afieldstudy
wassetupatFeltLaketoevaluateany
seasonalchangesthatmightoccurinthe
respiratoryrateswithrespecttobody
weight,variousswimmingrates,temperature,sex,andgrouping.
DESCRIPTION OF FELT LAKE
FeltLakeisareservoir,retainedbyan
earth-filldam,ontheStanfordUniversity
campus.ItisaboutfivemileswestofPalo
0
Alto,California,atLat.37 24'NandLong.
122°14'W.Theinflowisviaaone-half
milediversionditchfromLosTrancos
Creek.Abovethediversionthedrainage
basinconsistsofabout5.4squaremiles;
immediatelytributarytothelake,the
drainagebasinconsistsofabout110acres.
Rainfalltotheextentofabout15inches
peryearoccursmostlyfromNovember
throughMarch.Thesewinterrainsmaintainthereservoirata300milliongallon
capacitywithasurfaceareaof46acresuntil
aboutMay.Theleveldeclineswithirrigationneedsabout10-12feetbylatesummer
whenthevolumeisabout125million
gallons.In1956-57thelakewasfullfrom
MarchtoJune.FromJunetoOctoberthe
leveldroppedregularlyatotalof10feet.
SEASONAL CHANGES IN BLUEGILL METABOLISM
DuringtheverydryNovemberandDecemberperiodtheleveldroppedonlyonefoot.
Thelake filledduringJanuaryandFebruary,1957.
The1956-57surfacewatertemperatures
rangedfrom8.0-26.5°C.Formationofa
partiallystablethermoclineinsummerand
partialhypolimneticoxygendepletioncan
occur;however,theoxygencontentofthe
surfacewatersremainednearsaturation
levelsduring1956-57.
Fromspringthroughautumnthelittoral
areastendtohaveafairlydensegrowthof
weedswhichfollowlakewardthedeclining
waterlevel.Consequentlythelittoral
fauna,whichreachesitspeakinlatespring,
ispoorlydevelopedincomparisontolakes
withconstantlevels.Itisestimatedthat
anaveragevolumeofstomachcontentsfor
springandearlysummerwouldbeatleast
1-2cc.Frymire(unpublishedM.S.thesis)
hasshownthatthebottomfaunaasafood
supplyforbluegillswhoseforklengthswere
125mmandoverisseverelycurtailedby
autumnwhentheaveragevolumeofstomachcontentsdeclinedto0.20ccperfish.
Byearlywintertheaveragevolumehad
declinedto0.17cc,withmolluskandplant
remainsmakingupalargeportionofthe
stomachcontents.BylateMarchinsects
wereagainimportantfoods,andtheaverage
volumeofstomachcontentsroseto0.52cc.
Onthebasisofseveralhundredlength
andweightmeasurementstakeninearly
MayandagaininearlyNovember,1956,
forfishinthefork-lengthclassesof125149mmand150mmandover,itisapparent
thatthereisamarkeddeclineincondition
(weightperunitlength).Inthespringthe
smallerclasshadrespectiveaveragesof
lengthandweightof138.4mmand54.8g,
whiletherespectiveaveragesforthelarger
classwere158.5mmand90.1g.Thecorrespondingdataforautumnwere139.7mm
and50.5g,and157.4mmand75.5g.
Thebluegillisthedominantspeciesinthe
lake.Fromunpublishedpopulationdynamicsstudies,thegrowthandrecruitment
israpidonlyinthespringandearlysummer
whenthepopulationoffishwhosefork
lengthsare125mmandovervariesfrom
20to25thousand.Followingthelatesum-
197
merandautumnperiodsofpoorgrowthand
highmortalityratesaccompaniedbyahigh
incidenceofparasitism,thispopulationis
reducedbyasmuchasone-half.TheadversewinterconditionspersistuntilMarch
warmingwhenthesmallerfish,especially,
starttogrowrapidlyandbegintospawnin
ApriltoMay.Thelargerbluegillsstartto
growsomewhatlaterandbegintospawn
fromMaytoJuneandcontinuespawning
aslateasAugust.
FeltLakealsohasasmallpopulationof
largemouthbass ( Mieropterus salmoides)
andverysmallpopulationsofthebrown
bullhead (letalurus nebulosus) andthesculpin (Cottus asper).
FIELD PROCEDURES
Bluegills wereobtainedby seiningor
trappinginsurfacewaters.Theywere
retainedinalivecarforaperiodofatleast
onehourbeforemeasurementoftheir
respiratoryratesinarespirationchamber.
Allrespiratorymeasurementswerecarried
outinthefieldfromMarch,1956,through
February,1957.
Therespirationchamber,describedby
Wohlschlag(1957),isacircular,completely
enclosed,transparentplasticchamberwhich
canberotated.Rotationwaseffectedby
suspendingthechamberfromaninverted,
spring-wound,phonographmotorwhose
velocitycouldbecontrolledbyamanually
regulatedgovernor.Intheearlierdeterminationsthemotorandchamberweresuspendedfromafour-leggedderricksetupin
shallowwaternearshore.Laterdeterminationsweremadewhentherigwassuspendedthroughadeckhatchofaraft
locatedatthecenterofthelake.Approximatedimensionsofthechamberare:outside
diameter,45cm;insidediameter,25cm;
depth,10cm;andvolume,10,400ml.A
completerevolutionbyaswimmingfish
wouldequaladistanceofaboutonemeter.
Foreachdeterminationfreshsurfacelake
waterwasaddedtothechamberthrougha
funnel-likereservoirandconnectingplastic
tube.Fishwereintroducedthroughalid
whichwasthensealed.Runsweremade
withsinglelargefishduetospacelimitations
withinthechamber,butsmallerfishwere
198
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
oftenusedingroupsoftwotoeighteen
dependingupontheirsizeandavailability.
Bubbleswereremovedthroughtheconnectingtubeofthereservoirandtheentire
chamberwasloweredbyapulleysystemso
thatitwasbarelyimmersedinthelake.
Thechamberwasthenrotatedatwhatever
approximatelyconstantvelocitythefish
wouldtendtomaintain.
Samplesofwaterforoxygenanalyses
werewithdrawnthroughanoutlettube
afterthechamberwasraisedabovelake
level.Simultaneouslyfreshwaterfrom
thereservoirreplacedthewithdrawnwater
withouttheintroductionofbubbles.These
samplesweretakeninitiallyandat10to15-minuteintervalsoveraperiodof
one-halftoonehour.Theoxygencontentsofthesamplesweredeterminedby
themodifiedWinklermethod.Exceptfor
thespringmonthsof1956alloxygenanalyseswerecompletedinthefield.
Whilerespiratoryratedeterminations
wereunderway,temperatureandrotation
velocitieswereperiodicallyrecorded;after
therunthesedatawereaveraged,thefish
wereweighed,andnotesweretakenonsex,
sexualdevelopment,stomachcontents,and
visibleparasites.
RESULTS AND COMPUTATIONS
Field data
Todeterminetherateofoxygenconsumption,orrespiration,theoxygencontentof
thechamberwascalculatedforthetimeof
eachwatersampling.Asystematiccorrectionwasmadetoallowfortheadditional
oxygenintroducedintothechamberby
thefreshwaterwhichreplacedthewithdrawnwater.Foreachrespirationrunthe
correctedoxygencontentsofthechamber
wereplottedagainstelapsedtime.The
leastsquarescalculationoftheslopeofthe
beststraightlinethroughthesefouror
fivepointsyieldedtherespiratoryratein
milligramsofoxygenconsumedperhour
forthetotalweightofthefish.InAppendixTablesA—Darelistedtherespiratory
ratesinlogarithms(Y),thelogtotalweights
( X 1 ), theswimmingvelocityinmetersper
minute(X2),thetemperatures(X3),and
themetabolicrates(Y1)expressedaslog
milligramsofoxygenconsumedperhour
perkilogram.Thefour"seasons"into
whichthesedataareseparatedarearbitrary
delimitationsof:(1)aperiodofrapidlyincreasingtemperatureandspawningactivityinspring;(2)awarmsummerperiod
withdecliningwaterlevels;(3)along,late
summerand autumnperiodoflowwater
levelcharacterizedbydecliningtemperatureandbenthosandbyarisingincidence
ofstarvationandparasitism;and(4)a
coldwinterperiodofwinterrainswithhigh
andturbidwaters.
Multiple regressions
Theinterrelationshipsoftheexpectedlog
oxygenconsumption(Y e),whichisdependentonthelogbodyweightingrams
(X1),theactivity(X2)inmetersperminute,
andtemperature(X3)indegreescentigrade,
canbeexpressedasamultipleregression
(Wohlschlag1957).Routineprocedures
inmoststandardstatisticsbooks, e.g.,
Goulden(1952)andSnedecor(1956),are
availableforthecalculationofthemultiple
regression,
b1
Ye = constant ±
b2 X2 ±
b3 X31
whereb1isthepartialregressioncoefficient
ofYonX1withconstant X2 and X3,b2 is
thepartialregressioncoefficientofYon
X2 withconstant X1 and X3, andb3isthe
partialregressioncoefficientofYon X3
withconstantX1and X2.
TheregressionsbasedondatainAppendixTablesA—Dhavebeencalculated
intwoways.Thefirstmethodinvolvedthe
valuesYandX1astabulatedforthetotal
oxygenconsumedforthetotalweightof
fishinthechamber;thesecondmethodinvolvedYasthelogaveragemilligramsof
oxygenconsumedperhourperfishand X 1
asthelogoftheaverageweightperfishin
caseswheremorethanonefishwasenclosed
inthechamber.Regressionsbasedonthe
firstmethodaregiveninEquations1-5in
Table1,whiletheregressionscalculatedon
a"perfish"basisaregiveninEquations
6-11.Calculatedvalueshavebeenrounded
tofourdecimalplaces.Reasonsforthe
variousseasonalbreakdownsarediscussed
below.Otherusefulregressionstatistics
SEASONAL CHANGES IN
BLUEGILL METABOLISM
199
TABLE 1. Regression equations for Felt Lake bluegills relating log oxygen consumption rates (Y,) to
log body weight (X 1 ), swimming velocity (X2), and temperature ( X3)
Number of
determinations
Season
Regression equation
For total weights
March-June
Apr.-June
July-Aug.
Sept.-Dec.
Jan.-Feb.
31
23
22
40
22
Apr.-June
July-Aug.
Sept.-Dec.
Jan.-Feb.
Jan.-Feb.
(active fish)
Jan.-Mar.
23
22
40
22
15
Y, = -0.7248 ± 0.8232X1 + 0.0158X 2 ± 0.0132X 3 (1)
17 , = -1.6459 ± 1.3132X1 + 0.0167X2 ± 0.0107X 3 (2)
Y, = -1.9808 ± 0.9571X 1 + 0.0140X2 ± 0.0557X 3 (3)
Y, = -0.6912 + 0.7167X1 ± 0.0107X 2 ± 0.0235X 3 (4)
Y, = -1.7517 + 1.2167X 1 + 0.0091X 2 ± 0.0439X3 (5)
For average weights
Y, = -0.6954 ± 0.8036X1 -I- 0.0250X2 + 0.0069X3 (6)
Y, = -2.1951 + 1.0621X1 + 0.0138X 2 ± 0.0567X 3 (7)
V. = -0.9242 ± 0.8494X1 ± 0.0142X2 + 0.0198X 3 (8)
17 , = -1.0603 + 0.9630X 5 - 0.0002X2 ± 0.0251X 3 (9)
Y, = -1.9310 ± 0.8624X 1 ± 0.0427X 2 + 0.1153X 3 (10)
30
Y, = -0.6799 + 0.8235X1
0.0063X3
0.0107X 3 (11)
TABLE 2. Felt Lake bluegill oxygen consumption regression statistics
(See Text and Table 1.)
Standard errors of estimate,
Equation
Dzeleosin of
Stoafnetridin:r
t reor
Log wt., xi
R.123
1
2
3
4
5
6
7
8
9
10
11
27
19
18
36
18
19
18
36
18
11
26
0.1351
0.1472
0.1021
0.1662
0.1742
0.1737
0.0582
0.1631
0.1932
0.1119
0.1547
sb,
Multiple correlation
0.7010
0.6070
0.8414
0.5867
0.5970
0.9067
0.9914
0.8468
0.6495
0.8787
0.5943
P
<0.01
<0.05
<0.001
<0.01
<0.05
<0.001
<0.001
<0.001
<0.05
<0.001
<0.01
for these equations are given in Table 2
with probabilities (P) indicated for the
overall multiple correlation (RŸ.123) and the
individual partial regression coefficients
(b1, b2, and b3 ). Probabilities are referred to
tabulated values at levels 0.001, 0.01, 0.02,
0.05, and 0.1 to 0.9 by tenths.
Sex and metabolic rates
While the experiments on single fish were
not designed specifically for a comparison
of male and female metabolism, the following
schedule for the comparisons of the Y1
(log 02 consumption rate per unit body
weight) in the Appendix is of interest:
P
sbi
0.1872
0.4786
0.2413
0.3174
0.4336
0.1274
0.0337
0.1037
0.3432
0.2050
0.2393
<0.001
<0.02
<0.001
<0.05
<0.02
<0.001
<0.001
<0.001
<0.02
<0.01
<0.01
for partial regression coefficients
Activity, x,
sb2
0.0060
0.0082
0.0063
0.0067
0.0170
0.0113
0.0035
0.0070
0.0188
0.1054
0.0084
P
Temp,
P
sò 3
<0.02 0.0099
<0.10 0.0123
<0.05 0.0170
<0.20 0.0071
<0.70 0.0327
<0.05 0.0161
<0.01 0.0095
<0.05 0.0076
>0.90 0.0366
<0.02 0.0316
<0.50 0.0093
Average
xs
<0.20
<0.40
<0.01
<0.01
<0.20
<0.70
<0.001
<0.02
<0.60
<0.01
<0.30
Yi
Season
Males
Females
Apr.-June
July-Aug.
Sept.-Dec.
Jan.-Feb.
2.2378
2.2942
2.1674
2.1006
2.2590
2.4693
2.2209
2.1598
In all seasons the females have the higher
metabolic rates, but none of the differences
between sexes is statistically significant.
Effect of grouping
Indirect comparisons between oxygen
consumption rates (Y) of single fish and of
200
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
two or more fish may be made by utilizing
the Table 1 regressions (based on average
weights) to calculate the expected values of
oxygen consumption for the experiments
in which groups of fish were used. A
comparison of expected Y e and observed
Y. values is then possible.
For example, in the April-June period
Y e values may be calculated from Equation
6 (Table 1) and compared with the observed
rates Ye in Appendix Table A as follows:
Experiment No.
11
18
19
20
23
26
27
28
29
30
Yo
Yo
1.143
1.312
1.258
1.332
1.277
1.088
1.034
1.352
1.336
1.241
1.050
1.118
1.056
1.114
1.143
0.970
0.987
1.118
1.205
1.078
comparisons for the July-August period
obtain:
Experiment No.
47
48
49
50
Yo
Y,
1.075
1.481
1.268
1.300
1.207
1.569
1.277
1.258
Only the comparison for Experiment No.
50 indicates a higher value for the Ye, and
this is very likely explained by the agitation
among the three fish which included a
small ripe male and a small ripe female.
The September-December comparisons
based on Equation 8 and Appendix Table C
data are:
Experiment No.
Yo
Y,
56
57
64
65
69
76
78
95
96
1.353
1.105
1.192
1.268
1.100
0.989
1.108
1.157
1.118
1.111
0.872
1.170
1.161
1.140
1.053
1.078
1.065
1.196
All ten observed values are higher than
expected.
By utilizing Equation 7 (Table 1) and
the data of Appendix Table B, the following
30.
201,
A.
lot
0 2.
13
12
B.
11 -
0-
-'
9
/
7
2.5-
C.
\
2.4-
.
2.3-
•
2.22.12.0M
I
A
1
m
I
J
/
j
I
A
1
S
1
0
I
N
1
D
I
J
I
F
FIG. 1. Trends of 1956-57 Rat Lake averages for selected days. Surface temperatures in degrees
centigrade (Panel A), milligrams oxygen per liter at surface (Panel L), and log milligrams oxygen
consumed by blueells per hour per kilogram (Panel Cp.
SEASONAL CHANGES IN BLUEGILL METABOLISM
That six of the nine Y. are higher than expected hardly provides a significant indication of difference.
The January—February data contained
only one group determination. The March
data were inadequate due to temperature
variations.
Limnological conditions
Shown in Figure 1 is the trend of averages
of Felt Lake surface temperatures and oxygen contents and of the bluegill metabolic
rates for the days during 1956-57 when
field determinations were made.
EVALUATION OF DATA
Methodology
Fry (1957) gives excellent critiques of
laboratory methods for measurement of
respiration or metabolism. Wohlschlag
(1957) gives a critique of the field methodology pertinent to this study. There
appears no evidence to indicate that manipulation of gear or determination of the oxygen
consumption rates should involve any
systematic biases.
The oxygen content of the chamber
declined linearly on the average during each
run, and ordinarily did not drop below about
70 per cent of saturation. There was thus
no indication that respiratory rates decreased with time due to lower oxygen
tension as might be expected with relatively
large fish (Job 1955, Fry and Hart 1948a,
Fry 1957) or with relatively very active fish
(Graham 1949). The initial oxygen consumption rate during the first 10-15 minutes was not higher than average due to
excitement (Black et al. 1939), nor did the
fish show any symptoms of irritability
except in winter. In January—February
some of the inactive fish tended to have
excessively - high respiratory rates (see
Equations 9 and 10, Table 1). Otherwise
the bluegills were fairly placid whether
swimming or not.
There is the possibility that hour-tohour oxygen consumption rates could vary
with endogenous daily cycles as demonstrated by Clausen (1936) and others for
standard metabolic rates. However, all
observations in this study were from day-
201
light hours and are quite likely comparable.
Another source of hour-to-hour variation
occurred during the March, 1956, determinations when the respiration chamber was
in shallow water, and shoreline water temperatures increased rapidly during the day
to the extent of 2-3° above the temperatures
to which the fish were acclimated. From
Fry's (1957) review of thermal stimulation
and acclimation data related to metabolic
rates, it would appear that the March data
are apt to be unusually variable. A comparison of the January—February with the
January—March regressions (Equations 9
and 11) or a comparison of the March—June
with the April—June regressions (Equations
1 and 2) based on Table 2 statistics indicates the pronounced effects of the March
data. Hence it would seem desirable to
omit these data from further consideration.
From Figure 1 it will be observed that
April and May metabolic rates fluctuated
with surface water oxygen contents. The
significance of this relationship is unclear.
Since the oxygen contents for each run were
initially above 7 mg 02/L, it is unlikely that
respiratory dependence on oxygen would
be involved.
Linearity
Not only would interseasonal variation be
expected for some of the partial regression
coefficients, but there would also be expected intraseasonal variation over the
individual seasonal ranges of limnological
conditions. Should intraseasonal variations
be pronounced, curvilinear and time-series
analyses of the data would be necessary.
However, there are several reasons why the
linear analysis used here is satisfactory.
It is well known, at least since the time
of Krogh's (1916) studies, that the log
oxygen consumption rate plotted against
log weight is nearly linear. There may be
some exceptions at extremes of size ranges
(Zeuthen 1947, 1953), temperatures, activities, and low oxygen levels. Fry (1957)
discusses these interrelationships at length.
Since extremes were not encountered, and
since the partial regressions coefficients b1
are highly significant (Table 2), there is
good reason to consider the log oxygen
202
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
consumptionrate-logbodyweightrelationshipsessentiallylinear.
Linearityofthelogoxygenconsumptionswimmingvelocityrateishardertoevaluate.Afewworkers, e.g., Spoor(1946)and
Sullivan(1954),haveutilized"spontaneous
activity"measurementsofrelativelystationaryfish.Spoor'sdatawouldbeessentiallylinearifoxygenconsumptionrates
wereplottedlogarithmically,whileSullivan'sdatawouldnot.Mostotherworkers
haveconsideredactivityasbeingnegligible
indeterminationsof"standard"or"resting"
metabolismorasbeingmaximalona
sustainedbasis.IntheAppendixitwill
benotedthattherangeofactivityissmall
andthatthemaximumswimmingvelocities
aremuchlowerthanwouldbeexpectedhad
thefishbeenstimulatedtomaximumpossibleactivity.Becausetherangeofswimmingvelocitiesissmallandofaloworder
thelogoxygenuptake-velocityregressions
appearessentiallylinear,eventhoughthe
relationshipsoverawiderrangeofpossible
activitiesandtemperatureswouldbecurvilinear(FryandHart1948b).Onepronouncedexceptiontoalinearratedid
occurduringtheJanuary—Februaryperiod
whensomeofthenon-swimmingfishappearedespeciallyirritable.Forthe22
observationssummarizedbyEquations5
and9(Table1)thepartialregressioncoefficientsb2andthemultiplecorrelation
coefficientshavealowerorderofprobability
(Table2)thantheydowhentheseveninactivefish(AppendixTableD)arenot
consideredasinEquation10.Theobservedoxygenconsumptionratesforfive
ofthesevennon-swimmingfisharehigher
thantheexpectedvaluesfromEquations
9or10.Besidesappearingirritableand
refusingtoswim,fourofthesesevenfish
weredefinitelythinnerthantheaveragefor
thisseasonwhentheirphysiologicalconditionwasalreadypoor.Thusitwould
seemdesirableduringthecolderperiodsto
considerforregressionanalysisonalinear
basisonlythefishwhoseactivitiescanbe
measured.
Besidesitseffectonactivity,temperature
alsoinfluencesdirectlytheoxygenuptake
rateofpoikilotherms.Fromdatabasedon
standardandroutinemetabolismassembled
byFry(1957)itwouldappearthatthelog
metabolicorrespiratoryratesplotted
againsttemperaturemightbeatleast
slightlycurvilinearoverawidetemperature
range.Theannualtemperaturerangeat
FeltLakeisfairlysmall,andbybreaking
upthedataintoseasons,eachwithastill
smallertemperaturerange,itisreasonable
thatthelogoxygenconsumption-temperatureregressions b2areessentiallylinear.
Fromtheaboveconsiderationsonthe
effectsoflogweight,swimmingvelocity,
andtemperaturevariablesonthelogoxygen
uptake,fromtherelativelyhighmultiple
correlationcoefficients,andfromtheindividualpartialregressioncoefficientswith
smallstandarderrors(Table2)itmaybe
concludedthatthesevariablesmayjustifiablybetreatedonalinearbasis.
Total versus average weights of fish
Forthedeterminationsinvolvingmore
thanonefishinthechamber,aquestion
arisesonthesoundnessoftreatingthedata
eitherintermsofthetotaloxygenconsumedfortheaggregateweightofthefish
orintermsoftheaverageamountofoxygen
consumedperaverageweightoffish.If
totalsareusedtheregressions(Equations
1-5)arerestrictedtosmallerweightranges
thanisthecasewhenaveragesareused
(Equations6-11).Ifaverysmallsingle
fishwereinthechamber,itsoxygenconsumptionratewouldhavebeentoosmall
foradequatedetection.Ifaveragesfor
smallfisharecomparedwithindividual
measurementsforlargerfish,aquestion
arisesastothevalidmeasurementof
statisticalprecision.Bytheseason,comparisonsofequationsbasedontotalswith
thosebasedonaveragesofYandX1(Tables
1and2),indicatethatequationsbasedon
averagesare"better"withrespecttothe
statisticalsignificanceofparameters.Howeverillusorythestatisticaladvantagesof
thechoicemaybe,Equations6,7,8,and
10areselectedasbestrepresentingseasonal
relationshipsamongthevariables.
LIMNOLOGICAL CONSIDERATIONS
ThechoiceandinterpretationsofEquations6,7,8,and10ofTables1and2becomesimplifiedifthelimnologicaldataof
SEASONAL CHANGES IN BLUEGILL METABOLISM
Figure1andtheseasonalchangesinthe
behaviorofbluegillsareconsideredtogether.Theseequationsapplyonlywithin
therangeoftabulatedvaluesintheAppendixTablesA—D,andtheyapplyto
"populationaverages"undernaturalconditionsincontrasttomostpublishedinformationonlaboratoryacclimatedfish.
Seasonal delimitations
Forthe1956-57period,theutilizationof
watertemperaturechangeorstabilityas
criteriaforseasonalgroupingofthedata
isnotaltogetherarbitrary,sincechangesin
waterlevel,abundanceofaquaticinvertebratefoodsupply,andconditionofthefish
alsocorrespondedcloselytothethermal
characteristics.Sincelittleisknownof
seasonalchangesinrespiratoryormetabolic
ratesoffishes,itisthusprematuretouse
changesintheseratesthemselvesascriteria
fordelimitationof"physiologicalseasons."
Seasonalvariationinrespirationhasbeen
reportedbyWells(1935),andendocrine
changesassociatedwithgonadaldevelopmentandspawning,whichisseasonalfor
thebluegill,wouldundoubtedlyinfluence
metabolism(seereviewbyHoar1957).
Althoughsomeoftheindividualpartial
regressioncoefficientsdochangefrom
seasontoseason(Table1),usefulnessofthe
seasonalbreakdownisevidentfromthe
relativelyhighmultiplecorrelations(Table
2),whichwouldnotoccuriftherewere
largeintraseasonalvariationsinrespiratory
rates.
Effects of weight
Thepartialregressionsb1ofEquations
6,8,and10relatinglogoxygenconsumptionratetologweightareremarkablyclose
tothestandardvaluesof ca. 0.85givenby
Kroghandmanylaterworkers.Scholander
et al. (1953)observedapproximatelythe
samevalueforawidevarietyoftropical
andarcticpoikilotherms.Thesummer
valueof1.06(Equation7)ishigh,quite
possiblybecauseseveralofthelargerfish
wereinspawningconditionandmighthave
highermetabolicratesthanthesmaller
fishwhichhadpassedtheirspawningseason
(Fry1957,Hoar1957).Forfuturestudies
thefeasibilityofaddinganotherindependent
203
variable,suchasgonadweight,toprovidea
measureofsexualdevelopmentshouldbe
investigated.
Therearemanyargumentsforexpressing
weightsonanitrogenorproteinweight
basis(Gerking1952,1954,1955;Prosser
et al. 1950;Zeuthen1947,1953),especially
forthepurposeofreducingvariabilitydue
towideseasonalvariationsinfatcontent.
Sincetherespiratoryquotientforfatis
lowerthanforprotein,therespiratory
rateofafatfishwouldbelowerthanfora
leanone,allotherconditionsbeingequal
(Prosser et al. 1950).Inthisstudy,however,themagnitudeofseasonalvariations
inrespiratoryratesisperhapsbetterclarified
bytheuseoftotalweightswhichreflect
seasonalvariationsassociatedwithgrowth
conditions.
Effects of swimming velocity
Therelationshipsofthelogoxygenconsumptionratetoswimmingvelocity (b2
inEquations6,7,and8)areapproximately
thesame,consideringthefairlylargestandarderrorsinvolved.Fortheseequations,
thespring,summer,andautumnaverage
velocitiesare3.43,9.06,and6.85metersper
minutecorrespondingtorespectiveaverage
temperaturesof19.51°,24.07°,and15.30°C.
Noattemptwasmadetocalculateawinter
averagevelocitydueto"spontaneous"
activityofthenon-swimmingfish.Direct
observationsfromspringthroughautumn
indicatethatactivityofthefishfollowsthis
samepattern.Thespringincreasein
activity,whilecoincidingwithrisingtemperatures,mayalsobeinfluencedbythe
increasedoutputofgonadstimulating
hormones.Hoaret al. (1955)notethatthis
phenomenoncanincreaseswimmingactivity
andtherebyincreaseoxygenconsumption
ratesinsteadofincreasingmetabolism
directly.Theapparentlyhighrateof
swimmingintheautumnisarealphenomenonpossiblyassociatedwithincreased
effortsinseekingforthedwindlingfood
supply.Althoughswimmingvelocityvaries
considerablyoverthespring-autumnperiod,
thefactthatthepartialregressionscoefficientsdonotisapointofconsiderable
interest,inasmuchasthesamelevelof
respirationwithrespecttoswimming
204
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
movementsisimpliedoverthisperiod.
Thehighcoefficientforthewinterperiod,
however,maymeanthatmovementcan be
accomplishedonlyattheexpenseofamuch
higherrelativerespiratoryrate. Job's
(1955)datafor Salvelinus fontinalis show
thatthestandardrateasapercentageof
theactiverateofoxygenconsumptionat
5°Cisconsiderablylessthanthecorrespondingpercentagefortemperaturesupto
about14°C.IfJob'sactiveratesarefor
similarswimmingvelocitiesatthesetwo
temperatures,thentheregressionofoxygen
consumptiononswimmingvelocityfrom
standardconditionstoagivenactiveconditionwouldalsohavetobegreateratthe
lowertemperatures.
Effects of temperature
Fromtheconsiderableliteratureontemperatureacclimationandpreferendait
wouldappearthatthepartialregression
coefficientsb3wouldvarysomuchthatthey
couldbestatisticallysignificantonlyifthe
bluegillswereactuallyacclimatedtothe
temperaturesatwhichtherespiratoryrates
weredetermined.Thisconditionappears
tobegenerallyrealizedexceptforthespring
data.SincetheMarchdataareinadequate
becauseofwidetemperaturefluctuations
fromhourtohour,itisimportanttoexaminealsothetemperatureconditions
duringtheApril—Juneperiodforwhichthe
temperaturecoefficient0.0069isnotsignificantandisprobablytoolow.Duringthis
periodbluegillswillremainovertheshallow
spawningbedsinspiteofwideday-to-day
orhour-to-hourtemperaturevariations.
Unlessthereisadequatewind-drivencirculationofsurfacewaters,theseshallow
waterscanvaryanestimated5°Cdiurnally
fromhotcalmdaystocoolnights.That
spawningfishactuallyconfinethemselves
tothespawningbedsduringsuchfluctuationsisevidentfromobservationsduring
MayandJune,1955,whentherewasan
extensivekillduetooxygendepletionin
theinshoreareasofthelake.Atthistime
onlyspawningbluegillswerekilled;the
non-spawninglargemouthbassandbluegillswerepresumablyneitherkillednor
confinedtotheareasoftemporaryoxygen
depletionandwidetemperaturefluctuation.
Thusthereisgoodreasontobelievethat
spawningbluegillsduringthespringperiod
arenotalwaysthermallyacclimatedinthe
classicalsenseoflaboratorydeterminations.
FromacomparisonofEquations6,7,8,
and10inTables1and2,itappearsthat
thelogoxygenconsumptionrate-temperatureregressionsaredefinitelygreater
duringthesummerandwinter.Fry
(1957)discussesthisphenomenoninterms
ofroutineandactivemetabolismfor
Salvelinus fontinalis acclimatedtovarious
temperatures.Job's(1955)andSullivan's
(1954)dataforthisspeciesshowthat
oxygenconsumptionratescanberelatively
higherattemperatureextremes.Frybelievesthatthephysiologicalbasisforthis
conditionattemperatureextremesispossiblyduetoincreasesinspontaneousmovementswhicharenotreflectedinincreased
swimmingvelocities.Irritabilityandan
increaseinspontaneousmovementsmentionedabovedidoccurinthewinterbut
werenotespeciallynoticeableduringthe
summerfieldworkattemperaturesof
about23-26°C.Ahighlevelofspontaneousmovementsdidoccur,however,for
bluegillsinanaquariumatabout30°C.
Effects of sex
Thereislittleintheliteraturetoindicate
thatsexoffishhasanappreciableeffect
onmetabolism.However,muchofthe
experimentalworkappliestosexuallyimmaturefish.Formanylargerfishinthe
laboratorytherewouldalsonotbeexpected
theusualseasonalsexualcyclethatoccurs
innature.Fromtheinconclusiveresults
ofthisstudy,itwouldseemthatanyeffect
ofsexonmetabolismcouldbeestablished
inthefieldonlybyconfiningexperimentsto
morelimitedenvironmentalfluctuations.
Effects of grouping
Thephenomenonof"socialfacilitation"
foranimalsincludingfishesisgenerally
recognized(Alleeet al. 1949)atleastonthe
basisoflaboratoryexperimentation.From
thefieldstudyofbluegills,however,it
wouldappearthattherespiratoryratesfor
groupsarenotcorrespondinglylowerthan
SEASONAL CHANGES IN BLUEGILL METABOLISM
theratesforsinglefishinallseasons.The
groupsofbluegillsduringthespringand
theonegroupinthesummerthatcontained
sexuallymaturespecimenshadhigherthan
averageoxygenconsumptionrates.The
otherthreesummergroupsconsistingof
immatureorpost-spawningfishhadlower
thanaverageoxygenconsumptionratesas
wouldbeexpectedonthebasisofgoldfish
experimentsbySchuett(1934),Escobar
et al. (1936),andShlaifer(1938,1939).
Pritchard(personalcommunication)found
thatgroupsofbluegillsinlatesummer
consumedoxygenperunitweightatsignificantlylowerratesthandidsinglefish,
whileinwintertherewasnodifferencein
theratesbetweengroupsandindividuals.
Directobservationsofbluegillsandinformationfromseiningindicatedthatboth
spawningandnon-spawningfishofall
sizeslargelyconfinedthemselvestoshallow
watersduringthespringandearlysummer
inconcentrations10to100timesdenser
thaninlatesummerand autumnwhenthe
fishtendedtodisperse.Earlierinthe
seasonthefishwerewaryandantagonistic
towardeachother;later,wheninloose
schoolsandmorewidelydistributed,they
appearedmuchmoreplacid.BothSchuett
andShlaifernotedthatthenumbersinthe
groupswithinagivenvolumewouldinfluencetherateofoxygenconsumptionbut
notinastraightforwardinverserelationship.
Shlaifer(1939)foundthatvisionwasdirectlyinvolved.Whiletheresultsfrom
thebluegillexperimentswouldappearto
agreewithdirectobservationsundernatural
conditions,theresultsareinsufficientto
indicateeffectsofvaryingnumbersandthe
possibilitiesofacclimatingthespringand
earlysummerfishwithinthechamberso
thattheywouldexhibitsocialfacilitation
ratherthanantagonism.
SEASONAL EFFECTS ON BIOLOGICAL
PRODUCTIVITY
Gerking(1954) hasshownhowdatafor
bluegillmetabolismandpopulationdynamicscanbecombinedforanestimateof
thetotalproteinturnoverinapopulation.
Hedefinedproteinturnoverastheamount
ofproteinthatisrequiredbythepopulation
205
forgrowth,forthemetabolicexpenditure
ofenergy,andforthereplacementofproteinsbrokendownduringthenormalcourse
ofliving.Althoughtheweightdatainthis
studyareexpressedasliveweight,andnot
asproteinweight,Gerking'sconceptscan
beappliedatleastqualitativelytoaninterpretationofEquations6,7,8,and10
(Table1)withrespecttolimnological
variablesaffectingtheFeltLakebluegill
population.
Inageneralwaytheseasonaltrendof
metabolicratesvarieswiththetemperature
(Fig.1).Yetinthespringandearly
summerthefishnotonlygrowrapidlyand
getfatter,buttheirgonadsalsodevelop
rapidlyincontrasttotheautumnperiodat
similartemperatureswhenthefishtendto
loseweight.Sincetheobviouscauseof
theweightdeclineinautumnandwinteris
lackoffood,itwouldseemthatthepopulationcouldmaintainweightatthistime
ifmetabolic"efficiency"increased,if
metabolicratesdropped,orifthepopulationdecreasedsothatcompetitionfor
foodwaseliminated.Onlythelastconditionappearstobeevenpartiallyrealized,
andthereisnoevidencetoindicatethat
adverseautumnandwinterconditions
reducethereproductivepotentialinthe
spring.Iftherewereanykindof"metabolicadaptation"(akintohibernationor
aestivation)totheseseasonalextremes,it
wouldseemthatthemetabolicrateswould
thuschangemarkedlyfromspringthrough
autumnandwinter.
AcomparisonofEquations6and8for
anintermediatespringorautumntemperatureof,say,17°Cforobservedweights
andactivitiesyieldsexpectedrespiratory
(ormetabolic)ratesofthesameorderfor
thetwoperiods.Furthermore,theexpectedrates,calculatedfromEquations6,
8,and10overpertinentweightandactivity
rangesforawintertemperatureof,say,
10°C,arealsoofcomparablemagnitude.
Therethusisnoevidencefromtheseequationsthattherespiratoryormetabolic
ratesdeclineduringtheadversegrowing
seasonsmuchmorethanwouldbeexpected
solelyonthebasisofthedeclineintemperature,andpossiblyactivity.Thereis,
206
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
however,somephysiologicalbasisforthe
apparentlackofmetabolicadaptationto
poorfoodconditions.
Inthespringtheadditionoffatcanbe
explainednotonlybytheincreasedfood
suppliesandthegreaterfeedingintensities,
butalsobythefactthatatincreasedfeeding
ratestheretendstobeanincreaseinfat
content(Gerking1955).Gerking(1954)
reportedthatfatcontentcouldriseto
about33percentfornorthernIndiana
bluegills.Onthisbasisandonthebasis
thattherespiratoryquotientsforcarbohydrate,protein,andfatarerespectively
1.00,0.79,and0.71(Prosser et al. 1950),
adjustmentofthespringratesforfatfish
(Equation6)toaproteinbasiswouldbe
butslightlyupward.Inasimilarmanner
theincreasedplantconsumption(and
carbohydrateintake)intheautumnand
wintermightberesponsibleforhigherrates.
However,thereappearsnoconclusiveevidencethatcarbohydrateisactuallydigested,
althoughtheherbivorouspropensitiesof
thebluegillduringfoodshortageshave
beenwidelyreported(Ball1948,among
others).Gerking(1952)alsonotedthat
whiletwocentrarchidsabsorbedprotein
efficientlyatallages,youngerfishutilized
proteinforgrowthmoreefficientlythandid
olderfish.Inasmuchasmostallofthe
fishinthisstudywereafullgrowingseason
olderintheautumnandwinterthaninthe
spring,this"aging"phenomenonwould
alsoaccountforhigherratesbytheend
ofthegrowingseason.WhenEquation10
forwinterisusedtoestimaterespiratory
ratesatspringorautumntemperatures,itis
evidentthatthecomparablyhighrates
areprobablyexplainedby"coldadaptation"asdefinedbyScholanderet al. (1953).
Withaging,withcoldadaptation,and
withtheincreasingcarbohydrateconsumptionalongwithapoorerproteindietand
decliningfatreserves,itislikelythatthe
metabolicratesofbluegillsonaliveweight
basiswouldtendtoincreaseduringautumn
andwinter,otherfactorsbeingconstant.
Fromthestandpointofbiologicalproductivity,itmaybenotedthattheannual
growthratesofFeltLakebluegillsare
estimatedtobeofthesameorderasthose
reportedfornorthernIndianabluegills90
millimetersandlongerbyGerking(1954).
FromFigure1data,itappearsthatthe
PeltLakegrowingseason(attemperatures
above15-16°C,say),duringwhichthe
environmentisreducedtoabouthalfits
maximumwithanaccompanyingdecrease
intheproductionofbottomfauna,is
potentially atleasttwiceaslongasinnorthernIndiana.Allowingfortheinherent
dangersinbasingcalculationsonvariously
deriveddata,ageneralizedcomparisonof
Gerking's(1954)GordyLake,Indiana,
proteinturnoverdatawithcalculatedvalues
fromFeltLakeispossibleassumingthatthe
annualgrowthofthelargerbluegillsin
thesediverseenvironmentsisofthesame
order.Thisassumptionisjustifiedtothe
extentthatFeltLakebluegillsfromagesI
toIVhaveinstantaneousgrowthrates
roughlyequivalenttothoseofagesIItoV
inGordyLake(Gerking1954,Fig.2).
WhileFeltLakebluegillsgrowasmuchin
theirfirstyearasGordyLakebluegills
growintheirfirsttwoyears,thepoor
feedingconditionsandthehighmortality
ratesmakesurvivalandgrowthratesbeyondageIVverypoor.Hencetheaverage
instantaneousgrowthrateineachpopulationwouldbeofthesameorder.
ForanaverageGordyLakesummer
populationof8979fishweighing420.0
kgtheaverageweightofafishwouldbe
46.78g.ByinterpolationfromGerking's
(1954)TableIandFigure3,afishofthis
sizewouldrequireabout19gproteinfor
seasonalgrowthata31percentefficiency
ofproteinutilizationforgrowthalone.
Onthisbasis,forgrowth,metabolicenergy
expenditure,andproteinreplacementthe
totalseasonalproteinrequirementwould
beabout61gfora46.78gfish.Since
thereare,crudely,5.65Cal/gproteinand
1Loxygenconsumedingenerating4.82
Calupontheoxidationofmixedprotein
(Brody1945),thereareconsumed1.172
Loxygenpergramofoxidizedprotein.
Thustheoxidationof61gproteinperfish
wouldrequireabout71Loxygen.Since
Gerking'sgrowthexperimentswithpresumablyinactivefishatatemperatureof
25.9°Cindicatedthat150dayswouldbe
SEASONAL CHANGES IN BLITEGILL METABOLISM
required to account for the seasonal growth,
a direct comparison with Equation 7 (Table
1) for Felt Lake is possible. From this
equation the log mg oxygen uptake per hour
for a 46.78 g fish at 25.9°C and zero velocity
would be 1.0472, or 11.14 mg/hr, or 7.803
cc/hr. At the average summer swimming
velocity of 9.06 m/min in Felt Lake, the
oxygen consumption would be increased to
10.41 cc/hr. In 150 days 28 L oxygen
would be consumed at zero velocity or 38 L
at the average observed velocity. Both
of these Felt Lake values are much lower
than the 71 L calculated for Gordy Lake and
indicate that Felt Lake bluegills with a
long potential growing season have a much
lower production rate per unit weight of
fish.
Therefore, without apparent mechanisms
for suppressing maintenance metabolic requirements after the growing season or for
maintaining adequate food supplies to
allow for potential growth over the entire
growing seaon, the biological productivity
of the bluegill in western U. S. waters of
the Felt Lake type would be necessarily
poor compared to the productivity attained
in its native eastern U. S. habitats.
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BALL, R. C. 1948. Relationship between available fish food, feeding habits of fish and total
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BLACK, E. C., F. E. J. FRY, AND W. J. SCOTT.
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BRODY, S. 1945. Bioenergetics and growth.
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Reinhold, N. Y. xii
CLAUSEN, R. G. 1936. Oxygen consumption in
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207
tion of temperature to oxygen consumption
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208
DONALD E. WOHLSCHLAG AND ROGELIO 0. JULIANO
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APPENDIX TABLE
(I)
21 IV 56
5 V 56
12 V 56
19 V 56
2 VI 56
23 VI 56
(2)
x1
(4)
(3)
APPENDIX TABLE A:
(I)
(2)
1
2
3
4
24 III 56 5
6
27 III 56 9
10
7 IV 56 11
12
13
14
14 IV 56 15
16
17
12 III 56
(3)
1.493
1.534
1.533
1.312
1.292
1.316
1.330
1.008
1.143
1.127
1.112
1.624
1.234
1.131
1.148
xl
(4)
APPENDIX TABLE
0)
7171156
13171156
21 171156
28171156
14)711156
March-June Data
Xi
(5)
2.511 0.0
2.339 7.8
2.210 10.1
2.072 12.0
2.137 1.5
1.924 5.5
2.225 1.5
2.025 0.0
1.973 1.5
1.954 0.0
1.892 1.1
1.924 7.7
2.045 6.0
2.021 6.0
1.954 1.0
X3
(6)
(7)
14.8
17.8
17.8
17.0
17.6
15.5
16.4
15.0
17.7
19.3
18.5
18.5
14.0
14.9
14.9
1.982
2.197
2.322
2.240
2.155
2.393
2.104
1.983
2.170
2.173
2.219
2.700
2.189
2.109
2.194
yI
(8)
4
3
2
2
2
2
3
5
15 VIII 56
Xs
(5)
X3
(6)
(7)
(8)
18 1.312 2.072 0.5 19.7 2.240 5
19 1.258 2.004 0.0 20.5 2.254 8
20 1.332 2.065 0.0 21.9 2.269 5
21 1.022 1.881 8.5 18.8 2.141
22 0.946 1.944 0.0 19.0 2.001
23 1.277 2.124 0.0 19.0 2.154 5
24 1.229 1.982 1.1 17.0 2.247 1
25 1.206 1.954 6.7 21.0 2.252
26 1.088 1.863 1.2 20.0 2.224 8
27 1.034 1.903 0.6 20.0 2.131 7
28 1.352 2.076 0.0 21.0 2.276 6
29 1.336 2.000 5.8 21.5 2.336 3
30 1.241 2.009 0.0 23.0 2.233 2
31 0.925 1.924 8.5 22.8 2.000
32 1.452 1.978 12.5 22.8 2.474
33 1.511 1.982 10.3 23.0 2.529
APPENDIX
Felt Lake bluegill data tabulations by
seasons. Code for Tables A to D.
Column 1-Date of experiment.
Column 2-Experiment number.
Column 3-Log milligrams oxygen consumed per hour.
Column 4-Log weight of fish in grams.
Column 5-Activity of fish (meters per
minute).
Column 6-Temperature of water (°C).
Column 7-Log milligrams oxygen consumed per hour per kilogram.
Column 8-Sex: M, male; F, female; or
number of small fishes (usually immature).
A-Continued
(7)
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
Y
(3 )
B: July-August Data
Xi4
( )
Xs
(5)
Xa
(6)
(7)
(8)
1.4542.100 8.4
1.0601.845 1.0
1.3521.833 1.0
1.4681.99112.4
1.4261.99114.4
1.3931.914 9.7
1.3241.973 3.0
1.4781.88611.5
1.4912.00413.0
1.4611.96112.3
1.4281.88112.0
1.4932.01711.7
1.5492.000 6.7
1.0751.748 9.3
1.4812.083 9.7
1.2681.875 8.7
1.3031.908 9.3
1.2601.924 9.3
0.8681.785 8.3
1.3271.79211.7
1.2242.025 7.0
1.1031.833 9.0
23.5
24.2
24.5
23.1
23.2
24.5
24.5
25.8
25.0
25.2
25.2
26.0
26.5
25.0
25.0
24.0
22.9
22.0
22.2
22.2
22.5
22.5
2.353
2.214
2.519
2.477
2.435
2.480
2.351
2.592
2.487
2.497
2.547
2.473
2.549
2.327
2.398
2.393
2.391
2.336
2.083
2.535
2.199
2.270
F
AI
Al
F
F
AI
F
F
F
F
F
F
F
10
18
5
3
F
AI
F
AI
AI
Y1
September-December
Data
APPENDIX TABLE C:
(1)
17 IX 56
(2)
56
57
58
59
60
Y
(3 )
X%
(4)
A's
(5)
1.3531.806 5.3
1.1051.602 0.0
1.299 1.919 14.3
1.294 1.935 13.3
1.264 1.778 11.3
X2
(6)
21.5
22.0
22.0
22.0
22.4
Y1
(7)
(8)
2.547
2.503
2.380
2.360
2.486
8
9
F
F
M
209
SEASONAL CHANGES IN BLUEGILL METABOLISM
(1)
(2)
Y
(3)
XI
(4)
C-Continued
X2
(5)
Xa
(6)
APPENDIX TABLE 1):
January-February
Data
Y1
GO
00
(1)
18 DC 56
20 )C 56
3 )CI 56
17 )CI 56
1
1
13 )CI 56
1 X1156
13 )CII 56
14 )CII 56
61
62
63
64
65
67
68
69
70
71
72
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
1.1081.813 8.3
0.9351.83310.7
1.2291.82011.3
1.1921.924 7.3
1.2681.869 9.7
1.1981.833 6.7
1.2341.93510.3
1.1001.973 0.0
0.96011.892 0.0
1.2501 1.863 6.0
0.9381.792 1.3
1.0571.83910.7
1.2991.83310.7
0.9891.851 9.0
1.3411.820 7.3
1.1082.000 2.0
0.8311.81311.3
0.9441.75610.0
0.9211.82012.3
1.1171.799 5.7
0.7201.748 8.7
1.0461.973 7.0
1.0181.929 4.3
0.5551.845 0.3
0.9951.839 6.0
1.1091.845 8.0
1.1041.869 6.3
1.2071.92410.7
1.0461.898 4.3
1.0322.017 0.3
1.1631.903 0.0
0.4271.826 2.8
1.1571.973 5.3
1.1182.097 7.0
1.1661.869 8.2
21.3
21.5
22.0
18.0
18.2
19.0
19.1
19.6
14.9
15.0
15.5
13.9
13.9
14.0
13.9
13.9
12.0
12.0
12.5
12.5
12.5
11.0
11.1
11.9
12.5
12.5
12.0
11.7
12.0
12.3
12.3
11.4
12.0
12.1
12.2
2.295
2.102
2.410
2.268
2.399
2.366
2.300
2.127
2.068
2.387
2.146
2.218
2.466
2.138
2.521
2.108
2.019
2.189
2.102
2.317
1.972
2.073
2.089
1.709
2.156
2.264
2.235
2.283
2.148
2.015
2.260
1.601
2.184
2.021
2.297
Al
F
1
11
2
F
N4
2
F
NI
F
F
A4
2
AI
2
F
F
Al
F
NI
F
NI
Al
NI
NI
F
F
AI
AI
F
AI
2
2
F
12 I 57
(2)
98
99
16 I 57 100
101
102
103
104
105
25157 106
107
108
109
911[57 110
111
112
22 II 57 113
114
115
116
117
118
119
(3)
0.995
1.097
0.795
1.131
1.095
0.938
0.964
0.977
0.953
0.630
0.663
0.940
1.057
1.073
0.806
1.125
1.082
0.638
1.162
0.985
1.141
0.899
Xt
(4)
1.881
1.826
1.845
2.076
1.785
1.813
1.869
1.806
1.881
1.716
1.732
1.699
2.025
1.833
1.792
1.863
1.833
1.806
1.875
1.903
1.857
1.748
X2
(5)
9.0
0.0
5.3
1.7
6.3
0.7
4.3
4.5
6.7
2.7
5.0
6.2
1.7
0.0
0.0
0.7
0.8
0.0
0.0
0.5
0.0
0.0
(8)
8.2
8.4
9.0
9.1
10.0
10.0
10.0
9.5
8.5
8.5
8.4
8.5
9.2
9.2
9.4
11.9
12.0
12.0
11.9
11.9
11.9
11.9
(7)
2.114
2.271
1.950
2.055
2.310
2.126
2.094
2.170
2.072
1.914
1.930
2.241
2.031
2.241
2.013
2.262
2.249
1.832
2.287
2.082
2.284
2.150
(8)
4ft14't Ti't444't't4w
,
t44't
,
t, t4
,
t4
,
APPENDIX TABLE