MEASUREMENT AND PREDICTION OF PRIMARY PRODUCTION
AT AN OFFSHORE STATION IN LAKE ONTARIO l
by
P. Stadelmann and J. E. Moore
CANADA CENTRE FOR INLAND. WATERS
GREAT LAKES BIOLIMNOLOGY LAB.
867 Lakeshore Road, P.O. Box 5050
Burlington, Ontario.
This is the 6th report of work done by Great Lakes Biolimnology
Lab on Great Lakes.
1. The study was undertaken as part of the International Field Year
for the Great Lakes, a joint Canadian-U.S. contribution to the
International Hydrological Decade program.
1
Abstract
Photosynthesis rates using the 14C technique were
measured in situ in Lake Ontario and simultaneously in a
shipboard incubator.
There was good agreement between
maximum in situ photosynthesis rate and that obtained in
the incubator.
Empirical factors were computed by compar-
ing the photosynthesis rate obtained during a 4 hr. experiment (10 A.M. - 2 P.M.) with that for the whole daylight
period.
This relation showed that 36-58% of the daily
production occurred during this 4 hr. period.
At an off-
shore station annual production was estimated (185 g C m- 2
year-I) .
Daily photosynthesis rates using the "reference integral"
method were computed and compared with in situ daily rates;
both methods gave similar values.
80
Lake of Lucerne (47°N latitude - Gaechter 73)
------------ Lake Ontario (43°45' N latitude)
70
zto- 60
w
""0..
U
0:
W
D..
50
,,
0
,,
,,
,,
,,
,
40
~"
" "tr__
~;
0
//
/~
-------o.---o ... ~ LAKE
/
/
/
/
/
/
/
/
/
/~
/
...
-0---..
ONTARIO
30 -t---,-----.---,----,---,------r--,--'--,-----.------r--,---+
Jan
Feb Mar
Apr May
Jun
Jul
Aug Sep Oct
Nov Dec
FIG.
1
2/
Fraction of total daily photosynthesis (mg elm day) to be
expected during 4 hr. exposure (10: 00 -14: 00)
1972
1973
2000.,------------'----------------------------------,
OFFSHORE STATION (OOPS Stn.19 IFYGLl .
o measurement during the whole day
{', extrapolated values from 4 hrs. experiments
1500
>-
--E
t1l
U
1000
()
OJ
E
I:
500
0+----,-Apr
FIGURE
May
2
= 185 g Cm- 2 year·'
..... ··T
Jun
Jul
Aug
·····--·....,-·-·-....,·---,----··-1
Sep
Oct
2
Nov
Dec
···-·-T··-··-·..----··--··-
Jan
Feb
Mar
Daily carbon uptake rates (mg Cm- day -1) in Lake Ontario (offshore station)
3
Our main object during the International Field Year
for the Great Lakes was to'I'measure daily photosynthesis rates
at an inshore and offshore station in Lake Ontario in order
to estimate annual production.
In situ 14C measurements were
conducted on short-time intervalS-(2-4 hrs.) over the whole
day at various depths to 25 metres.
(For details see Stadelmann et. al. 1974) Photosynthesis rates obtained during noon
at the offshore station are shown in Table 1. Daily photosynthesis rates per m2 were determined by integrating the
observed values over depth and time and summing the results
for consecutive exposures.
When 14 C measurements were conducted only during a
4 hour period (10:00-14:00 EST), empirical factors were used
to convert results to daily production rates.
The values for
this factor as a function of season are shown in figure 1.
This relation shows that 36-58% of the daily production
occurred during this 4 hour period; the values for Lake
Ontario were lower than those found by Gaechter (1973) in
Lake of Lucerne.
In figure 2 daily photosynthesis rates per
m2 , based on measured and extrapolated values, are shown for
the offshore station. The daily production was integrated
over a period of one year (April 1972 to April 1973);, this
resulted in a primary production rate of- 185 g C m- 2 year-I.
Gaechter (1973) tested different mathematical relations to calculate daily production rates from short time
in situ measurements.
He found that the reference integral
method introduced by Vollenweider (1965) gave good agreement
between measured and calculated photosynthesis. Vollenweider's
expression gives daily production as a product of p t £ and
op .
E
an integral function which depends only on I'
(
)/I'k
o max
•
Best agreement was found using the following reference integral,
which takes into account inhibition of photosynthesis in layers
close to the surface.
.
Productlon
m- 2 day -1
=
J
I' o
11+
(x)/I" k
r.::' 0
. dx
(x)/2. 6
where:
=
production rate at light optimum (mg C m- 3 hr- l )
= day length (hr)
-E
= average extinction roefficient of the photosynthetically
useful spectrum (m- )
(1 )
4
I' o
= subsurface light intensity (ergs m-2 hr -1 )
I' k
= light intensity at the intersect between initial linear
slope and the height of the saturation plateau given by
Popt.
I' o (max) = highest light intensity at noon.
Fee (1971) has tabulated this reference integral
for different I'o/I'k values.
I' o (max ) can be determined from the relation
I'
o
(max)
=
2 E'
0
(2 )
Q,
provided that the daily insulation is symmetrical with respect
to mid-day and can be approximated by a cosine function.
E'
is the radiation energy input during one day, which can be ~o
measured with a shipboard pyranometer. The values I'k and E
can be obtained by plotting the relative photosynthesis (p/p
t)
op
on a semilogarithmic scale against depth. For a given production
curve - ~ssuming homogeneous distribution of phytoplankton and
all other environmental factors (with exception of light) in
the euphotic zone - and a known subsurface intensity (1'0) we
can directly obtain E and I'k (Vollenweider 1965, Fee 1971,
Gaechter 1973).
In Table 2 rand I'k values are shown for
the offshore station; the assumption of homogeneity was
verified by checking biomass parameters such as chlorophyll
a and particulate nitrogen. Daily carbon uptake rates were
computed by the method of "reference integral" and compared
with the in situ daily production. There was good agreement
between calculated and measured values, although during stratification temperature and nutrients were not always distributed
homogeneously in the euphotic zone and the solar radiation
was not always symmetrical with respect to midday.
In situ measurements of photosynthesis are tedious
and expenSIve for comprehensive studies or large bodies of
water such as the Laurentian Great Lakes, thus only few
stations can be investigated intensively over one year, and
alternative procedures are desirable.
Various approaches have been made in the Great Lakes
to avoid extensive in situ measurements; this was accomplished
by the use of light-rncubators on board ship. Saunders et ale
(1962) reviewed problems of surveying photosynthesis rates
on large areas. They extrapolated daily production rates
per m2 by determining (1)
the absolute photosynthesis rate
of a surface sample, which was exposed in an incubator providing optimal daylight conditions, (2) a correction ff~tor
for transparency of ·the water column using an in situ
C
experiments with surface phytoplankton as "photometer",
5
FIGURES 3 and 4 over
.)'
....
......
C')
20
I
i
•
•
/
•
x
20
r = 0.849
y = 1.01
•
-.
•
30
i
30
i
Popl. - mgC/m 3/ hr
10
I
. /.
•
STATION 11
•
20
i
r = 0.987
y=1.10x
Popl. - mgC/m 3/hr
10
••
•
I
i
FIG.3 RELATION BETWEEN CARBON UPTAKE
RATES IN SITU (popt.) AND IN INCUBATOR
(pinc.)
o
oI
~J
E
oOJ
E
........
C')
.......
J::
....
30j
o
oI
0:: 10
c
u
E
OJ
c? 20
E
J::
30
STATION 19
W
if)
~
IW
a:
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1%
OOPS STATION 19 (IFYGL)
10%
100%
•
FIGURE:'; VARIATIONS OF OPTICAL PROPERTIES AT THE OFFSHORE
STATION. THE PERCENTAGE TRANSMISSION OF THE
SPECTRUM 400 - 700 n m ( QSM READINGS )
~
I
0.1%
o
0'\
7
(3) a correction factor for inhomogeneous distribution of
the algae at different depths.
The final calculated profile
curve was obtained by multiplication.
Fee (1971) used a
light incubator on Lake Hichigan, in which C1 4 experiments
were conducted at four light_~nte~~ities ~100%, 30%, ?% and
5% of about 46.10 11 ergs
m
hr -).
USlng Vollenwelder's
photosynthesis model (1965) the carbon uptake rates obtained in incubator were converted to integral production and
related to the actual irradiance in order to estimate daily
production.
Glooschenko et al. (1974) estimated primary
~roduction using a shipboard--fncubator with a constant light
lntensity (8 klux = approx. 11.5'10 11 ergs m- 2 hr- l ).
~hey
extrapolated average daily production from pooled data on 32
Lake Ontario and 25 Lake Erie stations.
The prediction was
Performed by correlating incubator 14 C experimen·ts and Secc~i
depth readings wi·tIl results from in ~.:!:..tu experiments.
Incubator experiments (40.10 11 ergs m- 2 hr- l ) were
conducted simultaneously with the in situ photosynthesis
measuremen·t during noon in Lake Ontarioduring IFYGL.
Comparison of the maximum in situ photosynthesis rates at
light sa·turation (p . '
)-~/vitl~-rates obtained in the
,
b.j...
(,p,
.. op-clffium
f rom samp~es
. 1
t a k.en Wl
. ' th an
lncu
a~or
'
t
\
- lncuDa' or)
integrating sampler (O-··J. Om) indicated good agreement as
shown in figure 3.
The statistical relation between Pincubator
versus p t'
at the offshore station was P,
= 1.10p op t .
op lInum
lnc.
(r = 0.99).
The linear regression line at the inshore station
was p.lnc. = 1.01 P op t
(r = 0.85)
If P op't'lmum can be simulated
0
in the incubator and the vertical extinction coefficient for
the photosynthetically useful. energy in the water column and
the daily energy input of energy input is recorded, then the
only unknown is the value of I k" The information of I' k can
be obtained using different lignt intensities in the
incubator and the daily photosynthesis rates can be estimated
using only incubator measurements (Fee, 1971).
I
The variation of the underwater optical conditions
at the offshore station are given in figure 4; the data were
obtained using a spectrophotometer (Quantaphotometer Incentive
Res. & Div. A.B., Broma, Sweden.) From these -transmission
curves average extinction coefficient can be calculated.
The following are some recoI~mendations for primary
production measurements in the Great Lakes:
1.
If in situ carbon uptake measurement can be conducted
the:most efficient way is to choose a standard time exposure
(10:00-14:00) and to use empirical factors in order to get
day rates per square meter.
'~his procedure has the advantage that neither the radiation energy input nor the
extinction coefficient has to be determined (Gaechter, 1973).
Assuming homogeneous distribution of the phytoplankton in
the euph.otic zone the "reference integral" method will give
good results, if the light energy input during a day (E'o)
8
t'
, -E and Ilk are
op lmum
obtained graphically from an in situ photosynthesis profile.
is recorded.
2.
The parameters p
If carbon uptake rates are measured with an incubator
only, Feels method is recommended (Vollenweider 1970).
Samples from the euphotic zone should be collected with
an integrating sampler (Schroeder 1969) and exposed 2 to
4 hrs. to different light intrnsities (100%, 50%, 10%, 5%1 2%
of about 50.10 11 ergs m- 2 hr- ).
Fluorescent lamps are now available, which simulate natural
outdoor light (Vita-Fluorescent, Duro Test Corporation, North
Bergen, N. J. 07047).
The vertical extinction coefficient of the photosynthetically active spectrum in the water columns should be
measured with an underwater photometer and the incident light
intensity should be recorded.
9
REFERENCES
Fee, J. F., 1971. A numerical model for the estimation of
integral primary production and its application to Lake
Michigan. Milwaukee, University of Wisconsin, Centre
for Great Lake studies. Thesis l69p.
Gaechter R., 1973. Determination of the daily rates of the primary
production of phytoplankton. Models and measurements
in situ (in German) Swiss J. Hydrol., 35: 1Glooschenko, W. A., J. E. Moore, M. Hunawar and R. A. Vollenweider,
.
1974. Primary production in Lakes Ontario and Erie:
a comparative study. J. Fish. Res. Bd. Can. (in press) .
Saunders, G. W.! ~. B. Trama az;d R. W. Bachmann, 1962. Evaluation
of a mod1.f1.ed 1 4 C techn1.que for shipboard estimation of
Great Lakes Research
photosynthesis in large lakes.
Division, Publication No.8.
Schroed~r,
R., 1969. A summarizing water sampler.
aydrobiol.
66: 241-243.
Arch.
Stadelmann P., J. E. Moore andE •.Pickett, 1974. Primary
production in relation to light conditions, temperature
structure and biomass concentration at an inshore and
offshore station in Lake Ontario. J. Fish. Res. Bd.
Can. (in press).
I·
I
I.
,.
I·
Vollenweider, R. A., 1965. Calculation models of photosynthesis
depth curves and some implications regarding day rate
estimates in primary production measurements. Mem. 1st.
Ital. Idrobiol., 18 Suppl.,425-457.
Vollenweider R. A., 1970. Models for calculating integral
photosynthesis and some implications regarding structural
properties of community metabolism of aquatic systems.
IN: Prediction and measurement of photosynthetic
produGtivity proceedings of the IBP/PP Technical meet~ng,Trebon, Centre for Agricultural Publishing and
IDocumentation, Wageningen, Netherlands, 455-473 •
.
.
'
12/4
9:4514:00
(0.04)
0.74
0.63
(0.08)(0.08)
20
30
3.65
1.92
0.27
1.60
1.41
15
Incubator
mgCin- 3hr- 1
1.94
2.41
2.50
10
35.3
1.68
2.64
2.19
2.01
2.43
7
E mgCm- 2hr- 1 35.3
2.19
2.24
2.15
1.96
5
-
30.5
0.68
2.43
1.60
46.3
2.91
29.2
(0.04)
0.21
1.14
(0.27)
0.47
2.32
1.29
2.30
L30 _ .. 2.4L._ .. 1.18
1. 58
3
2.72
1. 74
0.29
1.54
0.25
0.69
34.3
16:08
30/5
14:00-
0.34
0.12
147.5
25/5
10:4214:38
1
0.57
41. 7
19/4
10:2313:57
0.10
-
141.0
13: 55
10:05-
18/4
0
Depth in
metres
xl0 1 ergs
m- 2 hr- 1 127.6
Enerp'
Date
Time EST
TABLE 1:
2.20
40;5
(0.17)
0.76
1. 58
2.42
2.70
2.63
1.86
0.70
0.24
106.5
3.26
50.5
0.08
0.60
1. 32
3.19
3.58
3.99
3.34
1. 53
0.67
61. 3
1 9 7 2
21/6
31/5
10:209:5514:00
13:55
2.69
35.2
0.05
0.61
1.62
2.74
1.94
1. 33
6.83
39.9
0
0.17
0.89
2.25
1.87
2.57
4.15
0
23.56
131.0
0
0.37
6.54
19.38
9.38
5.97
12.98
-
(2.46)
8.72
94.4
19/7
9:30
13:20
4.24
16.5
30/6
9:4613:46
0.87
76.0
29/6
9:5613:49
19.95
134.0
0.02
0.23
4.03
9.59
12.33
18.00
17 .68
11.09
86.2
25/7
9:47
13: 42
17 .87
86.2
0.03
0.25
1.40
4.67
6.99
14.00
14.00
9.31
64.8
26/7
10:05
13:50
-3 hr -1
Carbon uptake rates during noon at the offshore station, mg C m
(OOPS STATION 19, IFYGL)
I-'
C>
3.48
7.33
4.58
13.08
3.58
1.25
0.22
87.5
33.30
19.35
7.16
1.67
0
0.03
-
175.4
33.7
19.9
7.3
1.5
0.4
0
-
3
5
7
10
15
20
30
mgC~-3hr-1 33.75
incubator
Lm6Co-2hr-i 178.0
5.57
8.63
24.50
26.91
26.3
1
34.4
10.02
28.6
0.12
0.69
10.41
53.9
0
0.03
0.27
1. 34
3.07
5.24
10.2
Depth
0
23.18
82.5
23.6
106.0
102.3
Energy
7.59
51.0
44.7
8.36
-
0.19
0.62
1. 83
3.11
4.54
-
0.05
0.22
1.02
2.07
6.17
8.16
5.67
5.36
22.0
25/10
10:1214:07
Page 2
7.79
10.1
24/10
10:2514:03
19/10
10:4014:36
13/9
10:0414:00
-
Date
Time
TABLE 1
1972
12/9
7/9
10:35- 10:0114:35 13:47
1.88
24.8
Q
0.12
0.54
0.98
1.87
2.36
2.53
1.82
0.76
37.9
22/11
10:3014:20
1.81
36.3
0.07
0.54
0.81
-
-
-
20.4
8.4
17 .4
0.22
0.65
0.07
-
0.04
0.09
1.05
1. 53
0.44
0.28
1.63
1.49
0.58
70.0
7/3
10:1114:19
0.69
1.00
1.14
11.1
19/1
9:5914:04.
0
-
0.80
2.46
1. 61
1.10
1. 47
1.19
13.6.
1973
16/1
10:4714:25
2.54
2.95
1. 33
52.3
29/11
10:3515: 00
2.18
25.6
0.01
0.09
0.45
1.38
2.23
2.84
2.25
0.33
99.8
15/3
10:1514:00
35
2.00
23.4
0.05
0.20
0.57
1.
1.95
2.14
2.22
0.94
53.0
16/3
10:0013:50
I-'
I-'
15.2
-
814.7
786.0
144.8
-
64.0
-
14.5
-
14.9
14.1
15.0
14.8
-
12.6
12.5
-
9.0
9.2
-
-
8.4
-
11. 0
11. 5
21/16/72
29/6/72
30/6/72
25/7/72
26/7/72
7/9/72
12/9/72
13/9/72
19/10/72
24/10/72
25/10/72
22/11/72
29/11/72
19/1/73
7/3/73
15/3/73
16/3/73
614.0
407.0
111.6
70.8
-
31. 6
14.2
-
-
63.8
32.1
Ill. 5
-
106.2
109.0
23.5
97.6
-
106.1
200.5
702.6
-
165.4
272.3
-
768.9
-
31/5/72
-
-
47.2
30/5/72
294.9
12.5
153.8
0
-E
0.29
0.22
0.15
0.20
0.14
0.21
0.20
0.25
0.29
0.62
0.51
0.53
0.32
0.30
-
0.18
0.19
0.17
0.19
0.20
0.17
l' max =
E'o 2/ Q,
19/4/72
0
1031. 0
E'
13.4
£
-- -
k
12.0
6.6
21. 0
6.9
23.5
11. 4
9.9
7.1
30.9
7.0
14.0
12.8
23.3
27.6
-
8.6
10.4
13.2
10.6
7.5
15.1
Ii
5.89
8.03
9.30
10.72
3.33
2.20
2.22
3.22
3.18
2.00
2.67
4.59
8.21
7.99
4.56
3.95
-
11.34
-
6.29
10.18
Ii o II' k
647.5
1. 369
2.84
2.22
1. 63
1.14
2.95
2.53
6.17
8.16
1. 796
1. 836
1.193
0.914
0.919
1.193
1.174
0.861
1. 046
107.7
116.0
193.4
213.0
47.6
194.0
237.0
58.0
344.0
333.2
283.8
52.1
262.0
252.9
893.0
1443.0
1156.0
1241. 0
468.0
446.0
470.0
273.0
379.0
measured
f-'
tv
293.0
697.9
494.0
1. 413
24.50
8.63
1429.9
822.7
886.4
1186.2
-
418.0
398.1
1. 738
1. 727
900.0
-
226.8
230.3
240.1
152.0
computed
348.0
Q;
190.0
E
Popt·
1. 318
-
1. 843
1.565
1. 729
1. 581
1. 832
J
33.30
33.70
14.00
18.00
4.24
2.74
3.99
2.70
2.30
2.43
2.41
Popt
Comparison between computed daily production using the
"refeience integral" method (Vollenweider 1965) and
measured daily production in Lake Ontario (offshore station,
OOPS Station 19, IFYGL).
18/4/72
Date
TABLE 2
-