CLEAR TECHNICAL REPORT NO-255-P
00605-
255-P
905R82101
A PRELIMINARY REPOR"
ON THE DISTRIBUTION OF
CLADOPHORA IN THE
WESTERN BASIN OF
LAKE ERI E
Prepared by
Mark E0 Monaco
Richard Co Lorenz
Charles ED Herdendorf
Prepared for
UoS. Environmental Protection Agency
Great Lakes National Program Office
Region V, Chicago, Illinois
Grant No, R005555-02
Project Officer: Clifford Risley, Jr.
OHIO STATE UNIVERSITY
CENTER FOR LAKE ERIE AREA RESEARCH
COLUMBUS, OHIO
JUNE 1982
U.S. Environmental Protection Agency
GLNPO Library Collection (PL-12J)
77 West Jackson Boulevard,
Chicago, IL 60604-3590
-------
I
TABLE OF CONTENTS
I Page
• LIST OF TABLES ii
LIST OF FIGURES ii
I INTRODUCTION 1
Cladophora Survey of the Western Basin 1
I
I
I
I
I
I
I
I
I
I
I
I
I
LIGHT GRADIENT EXPERIMENT 2
DISCUSSION 2
-------
LIST OF TABLES
Page
1. Western Basin Cladophora Survey Observations, 1980 and 1981 ... 5
2. Cladophora Filament Length (CM) Increase During The Light
Gradient Experiment . 6
3. Comparison of Observed Depth of Cladophora Colonization to
Predicted 50 y E/m2 sec Depth 7
LIST OF FIGURES
Page
1. Western Lake Erie Cladophora Survey Station Locations 8
3. Cladophora Light Gradient Experiment, Filament Length Increase
at the Various Light Levels 9
n
-------
INTRODUCTION
Cladophora is usually associated with eutrophic waters and is referred
to as a nusiance alga, even though recent works indicate the important role
it plays in the nearshore community. The alga grows profusely in the
nearshore region of western Lake Erie and it commonly colonizes many different
substrates both natural and artificial, such as boats and breakwalls.
Recently a considerable amount of knowledge on the growth dynamics and
potential management of Cladophora in the Great Lakes has been gained. As
part of the Great Lakes International Surveillance Plan (GLISP) the Lake
Erie Cladophora Surveillance Program (LECSP) was initiated in 1979. The
Center for Lake Erie Area Research has investigated the growth dynamics of
Cladophora for the past three years at two routinely monitored sites visited
bimonthly from April to November. This paper is a part of the western
Lake Erie program that was sponsored by the USEPA.
The two routinely monitored sites are located at Stony Point, Michigan
and at South Bass Island, Ohio. To expand on this study, a survey of the
western basin of Lake Erie was conducted in late June of 1981 to determine
the areal and vertical distribution of Cladophora.
Cladophora Survey of the Western Basin
The survey was conducted using a coordinated effort consisting of a
boat, SCUBA tecniques and low-level aircraft to identify the major areas
of colonization (fig. 1). At 10 of the 23 stations visited, light was
measured as Photsynthetic Active Radiation (PAR) in units of y^/n2sec,
Secchi disk transparency, surface water temperature, biomass filament
length, % coverage, and maximum depth of growth was determined. At the
other stations, the presence of Cladophora and other major epilethic
filamentous algae were additionally notedT
A major portion of the western basin does not have suitable substrate
to support Cladophora. Much of the United States shoreline is low-lying,
consisting of unconsolidated sediments and the Canadian side has steep
erodable bluffs. The largest extent of bedrock is located in the Island
region of the basin.
Exposed bedrock is found along the shorelines and as shelves in the
eastern sides of most of the islands and as isolated peaks on the tops of
the major reefs.
Survey results identified Cladophora on the vast majority of all
suitable substrate in the western basin, including rocky shorelines, sub-
merged shoreline shelves, reefs and man-made structures such as concrete,
stone, wood and metal breakwalls, buoys and ships. In areas with unsuitable
natural substrate, the alga was observed on man-made structures, such as '
breakwalls and buoys.
-------
The depth to which Cladophora was found on the island shelves and
reefs varied with location (Table"!). Depth of colonization was generally
greater the further north the site was located. Correspondingly, Secchi
transparencies were greater and the extinction coefficients of light (K)
were smaller at the northern sites. Depth distribution of Cladophora
was greatest on the isolated reef areas, not located near land.
From the data generated during the survey and the three years of routine
monitoring, a field light value of approximately 50 yE/m2sec or less was
hypothesized to be limiting the vertical distribution of Cladophora
colonization in the western basin of Lake Erie.
LIGHT GRADIENT EXPERIMENT
To investigate the hypothesis that light levels of approximately
50 yE/m2sec or less are limiting Cladophora growth, a light gradient experi-
ment was performed in the laboratory at South Bass Island. The light
gradient experiement was designed to quantify the requirement to sustain
Cladophora growth, under conditions as close to the natural lake environ-
ment as possible. These values were then compared to the survey results.
The gradient consisted of ten 114 liter tanks with a flow through
water system. Water was pumped from the lake into the lab at a flow rate
of 57 1/hr. Water temperature was maintained at 15° C. and each tank
was agitated by two air lines venting near the bottom to provide water
movement and a constant temperature. Light levels were regulated in the
tanks from 0-170 yF_/m2sec. Light was measured using a Li-Cor Corporation
quantern light meter with a spherical sensor. Phosphorous and nitrogen
were routinely monitored and were not found to be limiting.
Values of PAR capable of supporting Cladophora growth were assessed
by the increase in filament length. The data presented in Table 2 represents
the average increase in filament length on a weekly basis under the various
light levels. After one week, growth was evident at light levels of
approximately 50 yE/m2sec and greater (fig. 3).
Two growth regimes are evident in fig. 3. At light levels of
approximately 50 yF_/m2sec and greater a much higher rate of growth was
obtained than at the lower light levels. Light levels of approximately
30-50 yE/m2sec supported a minimal amount of growth, as evident by the
steeper slope of the plots. At values less than 30yE/m2sec, growth was not
supported. From this data it was concluded that under laboratory conditions
that 30-50 yE/m2sec represented the minimal critical light value capable
of supporting Cladophora growth.
DISCUSSION
In extrapolating the results from the light gradient experiments to the
natural environment, several factors must be considered. The light levels
-------
in the gradient were constant for the total 14 hour light period being
instantly turned on or off resulting in either 100% light or darkness. The
14 hour laboratory photoperiod, as compared to the natural environments twi-
light effect results in a 40% greater total daily illumination in the lab.
If the light value of 50 yE/m2sec, which was generated from field obser-
vations is corrected for the 40% reduction due to the twilight effects, the
equivalent of the field value to a constant light intensity is 30 yE/m2sec.
This value correlates with the minimum light level of 30 yE/m2sec observed
to support growth in the laboratory experiment. Thus a light level of
approximately 30 yE/m2sec is limiting to growth under the constant light level
conditions in the laboratory which corresponds to a light value of 50 yE7m2sec
under natural daylight conditions.
To test the hypothesis that a value of approximately 50 yE/m 2sec would
be expected to occur under average conditions for the site. I has been
shown that,
, Iz = I0 e-KZ (1)
where: Iz = PAR at depth Z
IQ = incident PAR
K = extinction coefficient
Z = depth
The extinction coefficient (K) for each site was calculated from light
profile data taken at each site. Equation 1 may be rewritten as follows,
to solve for K.
K = InI0 - Inlz (2)
Once the extinction coefficient is know the depth at which 50 yE/m2sec will
occur at each site can be calculated by rewriting Equation 1 as,
Z = InI0 - Inlz (3)
K
where: K is site specific calculated value
Iz is 50 yE/m2sec, the minimum light value for growth
I0 is indicent light
-------
An average incident light (I0) value of 2000 yE;/m2sec was used in all cal-
culations to eliminate the variability between sites sampled at different
times of the day and under different weather conditions. The 2000 yE/m2sec
recorded at the two routinely monitored sites, from May - July, 1980.
Equations 3 thus becomes,
Z = In2000 - In56 (4)
site specific K
where: Z represents the depth at which PAR will be 50 y£/n2sec.
If 50 vi E/m2 sec is the minimum level of PAR capable of supporting
Cladophora the calculated depth from Equation 4 should be similar to the
field observed depth of deepest colonization at that site. The calculated
depth at which 50 y E/m2 sec was obtained and actual depth to which the alga
was observed compated well (Table 3). The several reef areas where the
50 y. E/m2 sec depth was greater than the observed depth of growth can possibly
be explained by the movement of sediment on and off deeper portions of the
reefs. For example, areas of sand were encountered on Chickenolee Reef.
Cladophora filaments may also have detached at the deeper depths prior to
the time of the survey in late June. Old holdfasts were evident at the
deeper deptsh of Gull Island Shoal.
The results of routine monitoring, the light gradient experiment, and
the survey of the western basin all support the theory that Cladophora in
western Lake Erie is light-limited at PAR levels below approximately
50 y E/m2 sec. The depth at which light attenuates to 50 y E/m2 sec in
the western basin varies from less than 2 m to over 7 m. The increase in
the turbidity of western Lake Erie over the past century that has contributed
to the decline of aquatic vascular plants (Stuckey 1979) may also have
decreased the total colonizable substrate available to Cladophora. If in
the future the turbidity of the basin decreases in response to decreased
loadings and phosphoros levels remain above 1 yg P/l the quantity of
Cladophora would increase due to a greater vertical distribution.
-------
CJ i-O
u o —
•o c.
"- E
J- CJ
CO
o
CO
en
00
z
o
or
LcJ
CO
CO
o
LU
>
c:
ZD
00
C-
o
CJ
on
<
CO
CJ VI •
wo ^
-i-i O
t/1
CJ JZ JC
Q. •*-»•*->
cj n. 3:
CJ CJ O
en
O
to i cc **•- d? oD 1 i r~^ vo *r r—< CA
• i ....ii
•—i I O O •—* O I ' O O O ••"" *—*
O LO CD CD CD UO LT> Ln O LO U~> O O
ooooooooooouc
C3 CJ CD CD OJC3CDC3CDC2a CJC3
CD CD CO
CJ Q?G? dOOJCJC.'CJ CI
cojccojccccccajc
oocjooajcjcjQjajcjocj
i co en
I CO •=•
I • •
I O O
o in o
to a\ c\j
CO VO
«j u o
ooo
j_ i. i_
•o TCI -a
QJ o ai
CD ca a
o cj cj
c c c
ooo
J-» JJ 4-*
VI l/> H
CJ CJ OJ
E e s
o
•o
o
10
.— o
C. O •
-a
c •—
-C 10 -o n>
JCCIJ
C •«—« ~" »-^ CJ VI V* CJ ^^ ^~
O ^J i/1) VI p-* -—• l_ •—» CJ "O v»
Q.CVI — *->
» — • — *O O t/» WO
•c —
^- 10 V.
v> O 2)
^- -C CJ
•/I
>i c: w
i— ia •—
c:
cj
CJ
o
o
o
i C3 Cu CJ v\ c
»Q i ^ ^— ' • (j j » "^^ ^_> (j "C3 *J C C3 ^^ *"^ U
• * v^ ^-^ f .*— vi T3 v* ^•~" ^3 Z3 • O fr*> irt ^^ *^
^ *O 3 C _^T CJ "~ ^ O *^~ O -^ Cn *O 3 *~
r :
5 >
-------
LU
_J
ca
LU
U1
«C I—
LU 2:
C£ LU
LU
*-» CX
2! x
O LU
h- LU
C3 •—•
o:
CD
LU
ca
CL.
o
CD
I— E
O U
CM
CO U
CO
CSJ U
1
10
£
o
o
ro
o
J_
10
U
0)
ui
CM
ir>
ur> LO
o
o
o
n
in
in
in
Csl
in
in
ir>
O O O r-«
oooooo
LT)
CM un
C\J
ID
-------
TABLE 31- .
COMPARISON OF OBSERVED DEPTH OF CLADOPHQRA COLONIZATION
TO PREDICTED 50^E/m2.sec DEPTH
LOCATION
1981
Marblehead Peninsula
East Kelly's Island
Gull Island Shoal
North Bass Island
Chickenolee Reef
East Sister Island
Colchester Reef
Middle Ground Shoal
Stony Point
South Bass Island
1980
Gull Island Shoal
*
Chickenolee Reef
Stony Point
South Bass Island
K
1.59
0.89
0.78
0.73
0.68
0.74
0.61
0.48
1.90
1.13
0.88
0.49
1.87
0.95
PREDICTED
Z50 ,uE/mZ.sec (n.)
2.3
4.1
4.7
5.1
5.4
5.0
6.1 **
7.7
1.9
3.3
4.2
7.5
2.0
3.8
KAX. OBSERVED
DEPTH (m)
2.5
4.5
3.2
4.5
6.0 *
4.5
7.0
4.8 ***
1.5
3.0
3.8
4.6 *
1.8
3.0
* portions of reef covered with sand
*•* light reading late in the day
*•** 'deepest depth not located due to flat and level topography of the reef
and the presence of gill nets
K - extinction coefficient
-------
(J
o
£T
O
CJ
i-
o
"S.
o
-o
03
C_3
OJ
•r-
1-
UJ
1-
(1)
xn
o
j_
3
en
8
-------
2nd week 3rd week
4th week
10-
9 -
8
7
6
5
4-
3 -
Z -
10
20 30
Filament Length (cm)
5u
60
Figure 3 Cladophora Light Gradient Experiment, Filament
Length Increase at the Various Liaht Levels.
-------
U.S. Environmental Protection Agency
GLNPO Library Collection (PL-12J)
77 West Jackson Boulevard,
Chicago, IL 60604-3590
------- |