Cyanobacteria in Hamlin Lake: An Impounded Riverine Lake
by Lisa Dennis
West Shore Community College – Summer Independent Study 2012
Hamlin Lake, a man-made riverine lake, consists of twelve square miles (5000 acres) of fresh
water fed by the Sable River within Mason County and emptying into majestic Lake Michigan. Hamlin
Lake is within Hamlin Township, the most populace in Mason County as per the 2010 US Census. The
recreational uses of Hamlin Lake have been important in the economy of Mason County. But, there is a
problem, literally, growing in the water that could very well change the economic status of the lake
which could spell a disastrous future for Hamlin Lake.
Although Hamlin Lake is a riverine lake it has been impounded by the construction of a dam. The
first of several dams on the lake was constructed in 1840 to aid the booming logging industry by way of
holding large numbers of clear-cut trees that were floated from further up the Sable River. In 1904
Hamlin Township consisted of approximately 35% less parcels as compared with today’s numbers (Gage,
2004). It was between this duration of time that a change took place in the business of logging along the
Big Sable River. White pine was no longer coveted as prime building material, and from the late 1800’s
to early 1900’s the original dam disappeared and the shoreline changed dramatically. In a short time the
lake depth receded and most of the land, once under adequate depths of water, became uninhabitable
bog and fen areas. This meant that one had to traverse dangerous terrain just to reach the edge of the
lake itself. In 1912 a plan was devised to fund the construction of a new dam returning the once
habitable riparian areas to their earlier state, and sell plots around the enhanced lake. By 1913 the dam
was complete, and is still in working order today.
It is this impoundment of the lake that is contributing to the growing eutrophic (polluted) status
of the lake. Sediment loaded with nutrients like phosphorous and nitrogen, in turn, affects the bottomup model necessary to a healthy population of plankton which are immediately essential to the health of
juvenile fish. Moreover, these high levels of nutrients can also be detrimental to the recreational use of
the lake by inducing an unhealthy bloom of blue-green algae, also known as cyanobacteria that can be
very dangerous not only to the health of the lake but the health of pets and humans.
Riverine lakes without impounding have greater protection against establishing eutrophic status
because the inflow and outflow patterns of moving water decrease the effects of sediment loading by
controlling levels of high nutrients in the sediments. Because of the stagnancy of non-moving waters
cyanobacteria (blue-green algae) species form rapidly. Hamlin Lake is a dimictic lake, which means that
it typically overturns twice annually. Floating mats of cyanobacteria keep the lake from naturally
overturning. It is when turnover (mixing) within the stratified lake layers becomes limited that the
formation of the toxic bloom-forming cyanobacteria becomes a big problem.
Planktonic and benthic cyanobacterial algal species that are nitrogen fixing (N-fixing) thrive in
sediment loaded areas. Cyanobacteria are not edible to most fish and zooplankton. Therefore the
problem has no natural solution and will not, in essence, clear itself up over time. And more important,
it is algae such as cyanobacteria that are used as indicator taxa of changing trophic status. The presence
of several types of cyanobacterial species in large blooms, or floating algal mats, on Hamlin Lake lead to
the potential eutrophic status which the lake now finds itself.
Higher than normal water level fluctuations (damming), little overturning, and anthropogenic
(man-made) activities that increase nutrient levels and result in a corresponding increase in numbers of
eutrophic indicator taxa deposited in the lake. Species of cyanobacteria can become dominant under
cases of anthropogenic influence, such as through nutrient dumping by the washout of fertilizer in
farming practices, also by heavy metal pollution, and drought conditions. Cyanobacteria algal species
form akinetes, dormant cells capable of reproduction in areas with low levels of nutrients, and can
thrive and alleviate the nitrogen limitation in a lake. When in combination with high levels of
phosphorous such as from fertilizers the abundance of cyanobacteria can grow exponentially out of
control.
Materials and Methods
The seven sampling dates were within a four month period and all yielded sample results from
four sites. Each of the sites locations was as follows: Site 1: Sunset Bay, Site 2: Indian Pete Bayou, Site 3:
North Shore, and Site 4: Deep Basin. Each of these four sample locations were mapped by satellite
coordinates in order to obtain as much accuracy as possible with the return samplings.
The study focused on lake nutrients, plankton net samples, and Secchi Disk measurements. The
intent was to see if the nutrient levels would coincide with the abundant algal bloom and how this fit
into explaining possible summer eutrophication of the lake.
The water samples were taken by Van Dorn bottle lowered one meter below the surface at each
of the four sites. One liter bottles of water were collected and marked for each site and analyzed within
24 hours in the lab using the LaMotte Smart Colorimeter 2. The nutrients measured in Hamlin Lake were
ammonia-N, nitrate-N and phosphate-P.
By pulling a plankton net behind a boat we collected qualitative samples from the four sites.
These samples were later examined under a Labomed digital microscope with a Motic 2.0 camera.
Photographs of specimen densities from each site, for each sampling day, totaling 28 separate samples,
were produced and saved. Relative plankton species were determined by analyzing prepared slides
under the microscope at different magnifications
Results and Discussion
The water samples provided a closer look into possible pollution concerns on upper and lower
Hamlin Lake and the concentrations were compared to studies from previous years.
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Mean-
June 27
July 10
August 4
August 11
Sept. 25
Oct. 2
Oct. 6
(By site)
Site 1
0.13
0.10
0.11
0.155
0.095
0.225
0.44
0.179
Site 2
0.16
0.09
0.28
0.145
0.16
0.415
0.40
0.236
Site 3
0.09
0.24
0.28
0.383
0.12
0.30
0.295
0.244
Site 4
0.13
0.47
0.48
0.177
0.175
0.225
0.205
0.266
Mean-
0.128
0.225
0.288
0.215
0.138
0.291
0.335
(By month)
Ammonia-N Concentrations
Table 1: Actual data for ammonia-N at all 4 sites, for the entire sampling season.
Ammonia-N
0.3
0.25
0.2
ppm 0.15
0.1
0.05
0
Site 1
Site2
Site 3
Site4
Average of 7 seasonal samples at sampling sites
Fig. 1: The average ammonia-N concentration for the season at all four sites.
Ammonia-N
0.4
0.35
0.3
0.25
ppm 0.2
0.15
0.1
0.05
0
June
July
4-Aug
11-Aug
Sept
2-Oct
Average of 7 seasonal samples by sampling month
Fig. 2: Seasonal data by month for average ammonia-N concentration.
11-Oct
Ammonia occurs naturally in drinking water and may stratify in impounded water. Ammonia is
considered a potential source of nitrates as it is found in the nitrogen cycle as NH₄ (ammonium) and NH₃
(ammonia) and theoretically as N₂ (gas). Here we will refer to the ammonia concentration as ammoniaN.
The data in Table 1 encompasses the actual figures from the water quality test for ammonia-N
for all days and all four sites. The range of ammonia-N is between 0.09 ppm (parts per million) and 0.47
ppm. Figure 1 shows the trend in ammonia-N concentrations in Hamlin Lake. The variation in the data
becomes most pronounced at sites 3 and 4. Concentrations decrease at site 1, while the data between
sites 3 and 4 appear to be those most affecting the lake water quality. The results obtained from the
data suggest that ammonia-N is a linear correlation comparable with the occurrence of cyanobacterial
blooms across all four sites.
The concentrations are at peak levels across all sites during the August through October period.
The collective levels ranged from 0.02 to 0.48 ppm. These levels are within the healthy range of 0.03
ppm, and were down from measured concentrations in 1999 of 0.73 ppm, and 2001 measured
concentrations of 1.76 ppm, the highest recorded, and in 2002 of 1.07 ppm.
Nitrate-N Concentrations
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Mean
June 27
July 10
August 4
August 11
Sept. 25
Oct. 2
Oct. 6
(By site)
Site 1
0.28
0.30
0.05
0.105
0.015
0.07
0.09
0.13
Site 2
0.24
0.27
0.02
0.017
0.05
0.11
0.11
.117
Site 3
0.24
0.17
0.18
0.07
0.07
0.115
0.085
.133
Site 4
0.29
0.12
0.01
0.13
0.04
0.15
0.08
.117
Sum
0.263
0.215
0.065
0.081
0.044
0.111
0.091
(By
month)
Table 2: Actual data for nitrate-N at all 4 sites, for the entire sampling season.
Nitrate-N
0.135
0.13
0.125
ppm 0.12
0.115
0.11
0.105
Site 1
Site 2
Site 3
Sampling Sites
Fig. 3. The average nitrate-N concentrations for the season at all four sites.
Site 4
Nitrate-N
0.3
0.25
0.2
ppm 0.15
0.1
0.05
0
June
July
4-Aug
11-Aug
Sept
2-Oct
6-Oct
Sampling Months
Fig. 4: Seasonal data by month for average nitrate-N concentration.
Nitrate is part of the collective nutrient balance in water as part of the nitrogen cycle. Drinking
water levels of nitrate should not exceed 10 ppm.
The data in table 2 gives the range of nitrate-N to be between 0.01 ppm (parts per million) to
0.30 ppm. The trend of nitrate-N in Figure 3 shows that site 1 and site 3 have the highest average
nitrate-N concentration possibly due to high residential use of these areas. Figure 4 shows the linear
trend in nitrate-N concentrations.
Concentration is decreased at site 2, and it is unclear from this comparison of concentrations
whether the decrease represents less nitrate-N or whether it is based on the increase in the
cyanobacterial bloom and their ability to make use of nitrate-N in the area. Levels of nitrates that are
intolerable to local organisms have been known to deplete dissolved oxygen levels by causing algae
blooms. This decrease in dissolved oxygen is a potential hazard for aquatic life in the lake.
These levels are within the normal range. In comparison, the data collected in 1999 showed
levels of 0.175 ppm, the 2001 samples had the highest levels of .424 ppm, 2002 showed levels of 0.071
ppm.
Phosphate-P Concentration
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Mean-
June 27
July 10
August 4
August 11
Sept. 25
Oct. 2
Oct. 6
(By site)
Site 1
0.05
0.05
0.06
0.09
0.08
0.02
0.25
0.086
Site 2
0.09
0.08
0.05
0.00
0.07
0.02
0.35
0.094
Site 3
0.02
0.03
0.06
0.015
0.08
0.02
0.03
0.036
Site 4
0.04
0.02
0.06
0.09
0.04
0.905
0.01
0.164
Mean-
0.05
0.045
0.058
0.049
0.068
0.241
0.640
(By
month)
Table 3: Actual data for phosphate-P at all 4 sites, for the entire sampling season.
Phosphate-P
0.18
0.16
0.14
0.12
ppm
0.1
0.08
0.06
0.04
0.02
0
Site 1
Site 2
Site 3
Site 4
Sampling Sites
Fig. 5: The average phosphate-P concentration for the season for all four sites.
Phosphate-P
0.3
0.25
0.2
ppm 0.15
0.1
0.05
0
June
July
4-Aug
11-Aug
Sept
Sampling Months
Fig. 6: Seasonal data by month for average phosphate-P concentration.
2-Oct
6-Oct
Levels of phosphates that are intolerable to local organisms have been known to deplete
dissolved oxygen levels by causing algae blooms. Phosphate is a nutrient that promotes the health and
survival of the aquatic organisms in the lake, but it can also be a limiting factor when it comes to
productivity when levels are higher than 0.03 ppm, and will initiate eutrophication of the lake. Immense
fish kills and algae blooms that are out of control and dangerous to the aquatic ecosystem are caused by
high sediment loading, a big part of the eutrophication process.
The actual data from each sample by sampling date is seen in Table 3 and ranges from 0.02 ppm
to 0.905 ppm. Figure 5 characterizes the average phosphate-P signatures. The concentration of
phosphate-P at site 4 is almost doubled compared to sites 1 and 2, and is six times higher than site 3.
The large variation in the data at site 4 represents an immensely unhealthy level of phosphate-P. That it
is found in such high concentrations in this area may be due to the flow through of water heading for
the dam which will eventually empty into Lake Michigan, or the discharge of pollutants may collect in
larger concentrations at site 4 also because of the depth of the area. The spike in the seasonal
phosphate-P concentration enlists a major spike in levels for early October, declining somewhat the last
sampling date.
During 1999 the average level of phosphate-p was 0.039 ppm, 2001 levels were 1.95 ppm, the
highest of all recorded concentrations, and 2002 levels were 0.199 ppm. The 2012 levels are above 0.03
ppm and are not within normal levels, and should continue to be monitored.
Nutrient Levels
0.4
0.35
0.3
0.25
Ammonia (NH₃)
ppm 0.2
Nitrate (NO₃)
0.15
Phosphate (PO₄)
0.1
0.05
0
June
July
4-Aug 11-Aug
Sept
2-Oct
6-Oct
Sampling Months
Fig. 7: Average nutrient concentrations for the entire season.
As seen in Figure 7 the average nutrient concentrations for the entire season shows a spike in
the ammonia-P concentration occurring in the last two sampling dates. The ammonia-N concentrations
show a pattern of peaking early in the sampling season and falling in the middle to eventually rise again,
to a higher level than previous samplings, at the end of the season. Phosphate-P concentrations are
highest in early October, climbing in concentration over the sampling season. The nitrate-N
concentration follows a declining trend over the testing period.
pH Levels
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
June 27
July 10
August 4
August 11
Sept. 25
Oct. 2
Oct. 6
Site 1
7.7
8.2
8.3
8.1
7.85
8.15
7.65
Site 2
8.1
7.9
7.6
7.6
8.1
8.0
7.95
Site 3
7.9
8.2
8.4
7.9
7.85
8.1
7.2
Site 4
8.1
8.2
8.2
8.0
7.8
8.25
7.9
Table 4: Actual data for pH levels at all 4 sites, for the entire sampling season.
pH
8.1
8.05
8
ppm 7.95
7.9
7.85
7.8
Site 1
Site 2
Site 3
Site 4
Sampling Sites
Fig. 7 The trend in average pH values for the entire sampling season at all four sites.
As an indicator of present amounts of hydrogen ions in the water supply of Hamlin Lake the pH
index is easily identifiable in two general terms: acidity and alkalinity. Each end of the pH scale
represents each end of the spectrum from acidity (0 being the most acidic) to alkalinity (14 being the
most alkaline), while a pH of 7, in the middle of the scale, is neutral. A range as close to 7 as possible is a
place all organisms try to reside to achieve homeostatic health and instill survival of the species. Waters
below a pH of 6.5 and higher than 9 are unfavorable to living organisms and can cause death of essential
species within the lake.
Table 4 represents the actual data collected for pH in Hamlin Lake, ranging from 7.2 to 8.4. The
concentration averages for each site for the entire sampling season, as shown in Figure 7, states these
levels are within normal limits.
The previous years testing gives pH levels in 1999 as 8.25, in 2001 as 8.125, and 2002 as 8.0.
These are all within normal levels and also promote a healthy aquatic ecosystem. There is no problem
with the pH factors within the lake.
Secchi Disk Depth
Site 1:
0.75 to 2.10 meters
Site 3:
1.00 to 2.20 meters
Site 2:
0.75 to 1.40 meters
Site 4:
1.3 to 3.5 meters
Table 5: Average Secchi disk depth range for the sampling season listed by site.
The turbidity of Hamlin Lake has an overall range of 0.75 to 3.5 meters. This part of the photic
region supports the majority of cyanobacteria populations; the sunlight penetrates as far as this range
will allow. It is this warm stratified layer that contributes to high cyanobacterial growth. Cyanobacteria,
or blue-green algae, thrives in shallow waters and will form mats or flotillas, much the same as has been
witnessed on the lake surface during this sampling season.
In 1999 the Secchi Disk depth averaged 3.25 meters, 2001 data averages were 6.35 meters, and
2002 averaged 3.1 meters. In comparison, Secchi Disk measurements for 2012 had an average of 2.55
meters.
Conclusion
Cyanobacteria are an old organism, dating back to before mankind inhabited the earth. Many
species can be found in bodies of water around the world and are considered to be the first group of life
that started producing oxygen. The problem is that many species of these cyanobacteria can cause
health issues. One hypothesis is that since cyanobacteria contain toxic material the toxicity can transmit
up the food chain. And through this transmission can have a negative impact on all levels of the food
web starting with reduced fecundity (fertility), and death, in the predators feeding on them, such as
Daphnia, a microscopic animal that is one of many that form part of the planktonic realm known as
zooplankton in aquatic ecosystems. There are many kinds of zooplankton that are an essential part of
the lower trophic (food or feeding) level in the food web, and cyanobacteria like Gloeotrichia,
Microcystis, Anabaena, and Aphanizomenon, all identified within Hamlin Lake, disrupt the food web by
outright killing the predators, sometimes faster than starvation, as noted in laboratory settings (Fey,
Mayer, Davis, and Cottingham 2-11). It is the eventual loss of these microscopic animals that tend to
mark a loss in juvenile fish that depend upon zooplankton as their major source of food. Imagine then
that fish are what make up the next trophic level in the food web and many other organisms including
humans eat these fish. It is these other animals such as birds and mammals that are part of the top
trophic level in the food web, and it is these large predator species which can contain an unnecessarily
high amount of toxins through a process known as bio-magnification. This same aspect applies to any
other toxins carried up the food web in many environments, not just in lakes. An example is the use of
DDT as an insecticide which had a huge impact on the shells of bird eggs.
Over-production of nutrients in an aquatic ecosystem will cause a disturbance of the natural
aquatic food chain. The over-production of phosphate-P concentrations shows a continuing problematic
trend in Hamlin Lake. This nutrient should continue to be studied and levels documented in correlation
to any further cyanobaterial blooms, and their algal dominance within the lake.
Species such as: Anabaena, Aphanizomenon, and Gloeotrichia are generally well preserved,
especially in organic sediments. And impounding provides a warm, shallow, and essential photic
environment for these species of cyanobacteria. Blooms of toxic cyanobacteria have been found as
indicators of decreasing cladoceran populations. Cladocerans are a big part of the trophic dynamics
within the food web. Diatoms are generally abundant during periods when high levels of cyanobacteria
are present. Fragilaria, Asterionella and Tabellaria are known to respond with increased production to
nutrient additions, especially phosphorus. These diatoms tend to increase as the trophic status
increases, and all three are found in rising abundance in each sample studied as the sampling period
continued throughout the season.
In places of high cyanobacterial blooms care should be taken with pets and human recreational
contact. Most importantly caution should be taken with these visible mats of blue-green algae that were
present in all but one sampling site. Toxic material secreted by decomposing cyanobacteria, known as
microcystins, has been known to cause skin irritation, cysts, gastric problems, and blindness. In rare
cases death of livestock and pets has been documented. A news report from the Indiana Department of
Environmental Management on August 30, 2012 warned that the death of two pets had been from
drinking/contact with lake water contaminated with toxic cyanobacteria ("Health Department warns
about the dangers of blue-green algae").
The acute health concerns for both humans and animals revolve around these cyanobacterial
toxins, known as microcystins. There are three known toxins emitted by cyanobacteria: hepatotoxins,
neurotoxins, and cytotoxins. The problem with these toxins is that the many health issues such as
hepatotoxins affecting the liver, neurotoxins affecting the nervous system, and cytotoxins affecting the
eyes and mucous membranes, each make the issue of finding cyanobacteria in Hamlin Lake one of great
importance (Carey, Haney, and Cottingham 337-339).
Species such as Gloeotricia, Anabaena, Microcystis, and Aphanizomenon, each found in Hamlin
Lake can cause immediate skin irritation in humans. The microcystin toxins within these species have
been documented as harmful to pets if they swim in or drink from an area that is experiencing a harmful
algal bloom or HAB (Schaedel A1-A7). Bodily contact through recreational use of the lake will not only
cause health issues, but also the decomposing mats of cyanobacteria could be essential in the reduction
of revenue from tourists and vacationers who come to the area and to those wishing to sell or buy
property on Hamlin Lake.
Drinking water can also be impacted by the toxins emitted by cyanobacteria. There are no
technological or purification methods available to remove these toxins, therefore rendering ground
water safe to drink. What is worse is that there are no standards documented by the EPA in regards to
drinking water contamination by microcystins because the guidelines are so hard to factor. Microcystins
have been added to the list of water contaminants needing further research, and Hamlin Lake is one
such area which may provide essential research detrimental to these greatly needed standards
(Schaedel A1-A7).
By being informed of the risks to the food web, the potential health concerns, and the need for
more research and through controlling the runoff of fertilizer from farming and lawn and garden
maintenance, regulating septic discharge, and governing land use that impacts water quality Hamlin
Lake cyanobacteria blooms may be controlled.
Hamlin Lake is one of the most prestigious and beautiful places on the Michigan map. Its rich
history and connection to Lake Michigan makes it a great place to be on a hot summer day. The process
of the growing eutrophication of the lake and the correlating repercussions from heavy sediment
loading by agricultural and anthropological factors should be held as high priority for the health of the
lake itself, and for the health and enjoyment of those who reside on the lake. If pollution by sediment
mixing is not controlled the cyanobacterial blooms will continue to be a rising problem.
Bibliography
Carey, Cayelan, James Haney, and Kathryn Cottingham. "First Report of Microcystin-LR in the
Cyanobacterium Gloeotrichia Echinulata." Environmental Toxicology. 10.12 (2006): 337-339.
Web. 10 Aug. 2012.
Fey, Samuel, Zachary Mayer, Stacy Davis, and Kathryn Cottingham. "Zooplankton grazing of Gloeotrichia
echinulata and associated life history consequences." Journal of Plankton Research. 32.9 (2010):
2-11. Print.
Gage, Kent. "Repairing the Hamlin Lake Dam." Rotary Lunch Presentation. Hamlin Lake Preservation
Society. Ludington. 20 May 2004. Speech.
"Health Department warns about the dangers of blue-green algae." abc 57 News: North Liberty, IN, 30
Aug 2012. Television. <http://www.abc57.com/home/top-stories/Health-Department-warnsabout-the-dangers-of-blue-green-algae>.
Schaedel, Andy. United States. Oregon Department of Environmental Quality. Harmful Algae Bloom
Strategy. Portland: Oregon DEQ, 2011. Print.