09-09-2005, 01:08 AM
The above average temperatures of this past summer that were brought on by longer and more frequent stretches of time the sun shone down on the county — a result of infrequent rainfall and cloud cover — sent a lot of folks scrambling into area lakes for some fun and heat relief, but that wasn't the only impact it had on area lakes. The summer's warm temperatures also resulted in an increase in water temperatures, which often spawns its own impacts on lake life, including greater growth of some aquatic weeds and algae, fish kills, and numerous beach closings.
Observers noted the hot and bright summer brought on increased growth of some weeds in certain lakes, greater growth of algae, and more beach closings, but no fish kills were reported in the lakes area.
Water temperatures influence a lake's ecosystem because they play a role in the water's dissolved oxygen content.
"What you'll see is lower concentrations of dissolved oxygen in the water because warm water holds less oxygen than cold water," said consulting limnologist Wallace Fusilier.
It's normal for lakes in Oakland County to be about 25 degrees Celsius, or about 77 degrees Fahrenheit during summer, according to Fusilier.
"Last summer we were seeing them at 22 and 23 degrees Celsius, so that's considerably cooler (than normal)," he said. "Last year was a cooler year compared to this year, which has been warm.
"(Dissolved oxygen) saturation at 25 degrees Celsius is 8.263 milligrams per liter," he said. "When we get to say 30 degrees, it's 7.559 milligrams per liter, so you can see it's almost one part per milligram less (oxygen in that warmer water)."
While cooler water will hold more oxygen than warm water, Fusilier said the relatively slight water temperature differences between last year and this year will not make an enormous difference on overall water quality.
According to Fusilier, water conditions are likely to be worse when they reach supersaturated oxygen levels because that would usually indicate a large algae bloom in the water or an unusually high number of aquatic plants in a lake.
"What you get (in warm water) is more algae and more weeds because there are some that like warm water," Fusilier said. "There are some that like cold water, too."
Weed harvesters, whose job it is to clean up the weeds in lakes, have encountered mixed findings with regard to aquatic weed growth this summer.
Eric Gleisner, of Inland Lakes Corp., which harvests weeds from 15 Oakland County lakes — many of which have weed harvesting conducted twice and three times a year — said he didn't notice too much more weed growth this season, but speculated on why it could look like there was or why algae grew more this year than last year.
"Some of it's perception. When the water level drops it looks like there's more weed growth," he said, noting that winter snow melt increases lake levels in the spring. "The other two reasons would be a huge amount of fertilizer run-off, and then the third would be improper use of herbicides in lakes, like a whole-lake treatment.
"If you do whole-lake treatments, you can implode the lake, and lose the dissolved oxygen levels at the bottom of the lake, and you cause this massive nutrient amount to form in both the hydrosoil and the water column, and the algae goes crazy."
Gleisner mechanically harvests lake weeds using machines similar to farm combines mounted on barges that are paddle-operated from each side. They're agile and can move around like a bulldozer or a Bobcat. A front table goes down under the water with a sickle bar and live bed conveyor, which cuts weeds down to a depth of five feet and removes the weed clippings from the water.
"The entire biomass of weeds in freshwater grows in the upper five feet to the sunlight," he said. "Below that is generally a stem. Weeds only really grow in 8 to 13 feet of freshwater. They're not a nuisance below that level."
Bob Pillotson, of Midwest Marine in Milford, which harvests weeds from 18 lakes in northern Oakland County and parts of Washtenaw and Livingston Counties, agreed that there are other factors in addition to warm water involved in aquatic weed growth.
"A lot of the lakes I do are private, non-zebra mussel lakes. In the experience I've had this summer, those lakes aren't really that bad, but on some of the zebra mussel lakes I've done, it's been extrememly bad," he said of weed growth this summer. "It's been pretty dry this summer, so if you don't get a lot of water in your lake, the weeds will grow faster."
Gleisner said zebra mussels clean up a problem that man created and only nature can take care of.
"(The mussels) filter out the planktonic algae that nobody can do anything with," he said. "They're taking care of one problem and creating another by making the water clarity better, and that makes the weeds grow more."
Aquatic herbicide applicator Dick Pinnagle, who serves as president of the Michigan Aquatic Managers Association, said he and other herbicide applicators have stepped up some applications this year; however, treatments have remained fairly level in 2005.
Additionally, Pinnagle said applicators are aware that herbicide treatments may have some negative effects if overused in warmer water.
"(We've had) more surface algae and chara algae treatments this year," Pinnagle said, "but not so much for milfoil.
"There are certain treatments that you can put in the water that have more of a time release aspect to them and don't provide such an initial hard hit as compared to other things. With the things that we put in that could potentially provide a quicker hit, we are backing those down or rotating treatment areas since the potential for fish kills has been heightened because of the warm temperatures. That's the main issue."
While Pinnagle noted some algae has been more noticeable this summer, he said heavy rain events in August helped to limit its growth by chipping away at it.
"It beats it up, but at the same time, it also washes new nutrients back into these lakes, so as soon as the rain stops and the sun is back out, you sort of get that flush again."
Aquest Corp. Limnologist Doug Pullman, who works as a consultant for herbicide companies, also said there seems to be more of some types of algae in lakes this summer.
"The algae really seem a lot heavier this year than in may years," Pullman said. "I think more than anything, we have probably seen fewer (herbicide) treatments because of the high water temperatures and the fear of fish kills.
"It's really hard to say that the algae is a lot worse. I don't have any solid proof, but it sure seems like it."
Pillotson added that at one lake he harvests weeds from, he encountered a type of growth he's never seen before.
"It was like a thorny naiead. It was terrible," he said. "It looked like it was something that would cut you if you walked on it. It grows down on the bottom with the chara; it doesn't grow up. It was all over, mixed in with the chara, which grows everywhere."
Pullman said that the appearance of more algae in some lakes may actually be suspended sediments in the water caused by increased boat traffic.
"I've been on a couple of lakes where there hasn't been algae in the water column but things are really stirred up from the boats," he said. "It may be algae in some places, but it may also just be suspended sediments from the boats."
Some aquatic weeds are also thriving in the warm water and growing faster and thinker than riparians are used to, but one weed that probably didn't fare too well this summer is Eurasian watermilfoil. Since it's a cold weather perennial, Pullman said its production is down significantly in a lot of lakes because the water is so warm.
"The only thing that really astounds me is that we haven't had more fish kills," Pullman said. "I haven't had any more calls than normal, but with such high water temperatures, that would be a logical thing to occur.
"When it all shakes out, it (was) just really, really hot out there."
While many people using the lakes for recreation may have noticed warmer water this year in Oakland County's lakes, the overall temperature of a lake was less likely to be much higher than normal.
"You have to remember that this warm water is only near the surface, and it doesn't go down very far," Fusilier said, adding that the top layer of warm water probably doesn't go down much more than about 15 feet below the surface in most inland lakes.
"Then it starts to get colder and there's that layer of water in there called the thermocline where the temperature changes rapidly with depth," he said. "Usually by about 22 feet, it's cold."
The thermocline, with its cooler water, is normally rich in oxygen, while the water below the thermocline is even colder and typically holds less oxygen. If the top and bottom layers of a lake are low in dissolved oxygen, which fish need to survive, the middle layer usually provides a safe haven for fish.
The relatively stable thermocline may be one of the reasons that biologists at the Michigan Department of Natural Resources (DNR) are not seeing many fish kills this year, despite the higher water temperatures near the surface.
"We haven't seen anything dramatic," said DNR Fisheries Biologist Jim Francis. "Sometimes we can see fish kills or something along those lines. (Warm water and low oxygen levels) can stress the fish out, but typically we don't see it where it stresses the fish to the point of mortality.
"Typically, when we see fish kills, it's kind of sporadic. It can hit some lakes, but we don't get a fish kill throughout a county or region. Each lake is a little bit different, but it's not uncommon when we have a string of 90-degree-plus days that we'll get one or two reports of some fish dying off in a particular lake."
As with some plants and algae, some fish are more likely to experience increased growth when exposed to warmer water. However, increased stress from water temperatures can also stunt a fish's growth.
"There's no question that in warmer water you can grow a fish faster and bigger, but there's also a limit," Francis said. "Once it gets too warm, you're putting additional stress on the fish, and it can actually retard the growth."
According to Francis, the DNR surveys a number of lakes throughout the year. Surveys typically include recording the water temperature and the chemical makeup of a lake. The only lake in Oakland County scheduled to be included in the DNR's survey this year is Big Lake in Springfield Township.
Limnologists typically measure an inland's lake temperature by beginning at the deepest part of a lake and using a probe to measrue temperature and dissolved oxygen. Measurements are usually taken from the surface to the bottom in 1 foot increments.
"Most fish can get in that cooler middle layer where there is still oxygen," Francis said. "Once you get down in the bottom layer, it's the coldest, but ... there's no oxygen so the fish don't do well down there. In the middle layer, the thermocline, they can typcially get in there and get the cooler water temperatures and there's still sufficient (oxygen) for them."
He said, however, that the surface waters probably don't have much of an impact on fishes' overall health.
"Surface temperature isn't necessarily an important thing because fish typically can find some temperature refuge," he said. "From a fish standpoint, I don't think (the summer's warm water is) making a huge difference."
But, while Francis said fish mortality may not be impacted to a great extent, the warm water has influenced fish behavior.
"Typically, the water is cold in early spring and as the spring progresses the water warms up," he said. "How quickly it warms depends on how fast the (air) temperature rises. What we saw this year is that the lakes were kind of cool for a while, and when the heat hit, it hit all at once, so I know the fish earlier in the year were kind of screwed up.
"I know some of them were caught off guard because there are a number of factors that determine when a fish spawns. Part of it's day length, but a major factor is water temperature."
Francis said many fish were waiting to spawn because the water earlier in the spring was too cool. When the temperatures suddenly shot up, many fish had failed to spawn and continued to hold their eggs because the water became too warm.
"We got reports in the middle of July that there were still fish that had eggs, which is way late. I think they were at the point of 'what do we do? Do we drop our eggs now or do we wait for the temperature?'"
While the heat may have caused weeds and wildlife to behave a bit different this year, people continue to be predictable: when the weather is hot, lots of people go to the beach. However, an increase in water temperatures may also mean an increase in bacteria, organisms that love warm water.
According to the Oakland County Health Division, several beaches the department monitored had to be closed because of unsafe levels of those warm-water-loving organisms.
The Oakland County Health Division's Environmental Health Services unit monitors about a third of the nearly 400 public and semi-public beaches in the county each year to determine if they are safe for swimmers. The program runs from June until the middle of August each year.
The department's monitoring program tests about 100 beaches every summer, with priority given to commercial and government-owned beaches, such as those at state, county and municipal parks.
Monitored beaches are to meet a one-day standard of no more than 300 bacteria colonies per 100 ml of water, and a 30-day geometric average standard of no more than 130 colonies per 100 ml. Beaches where water samples exceed those bacteria standards are closed until additional testing shows bacteria levels have dropped.
E. coli has become the target of beach water monitoring programs because it's an indicator of more harmful bacteria. Fecal coliform — the formerly used indicator — suggests a wide variety of bacteria that may not be especially harmful to humans.
Exposure to high levels of bacteria can cause such ailments as ear and eye infections, vomiting and other symptoms. Most recreational water illnesses are spread by swallowing, breathing or having contact with contaminated water.
Mark Hansell, the Health Division's environmental health services unit supervisor, said while high water temperatures may help promote bacteria, the two main factors that foster high bacteria levels in beach water are waterfowl and heavy rainfall.
The total number of Oakland County beach closings this past summer totaled 30 at 21 different beaches countywide, some for a period of multiple days.
The Health Department ordered 26 beach closings in 2004 at 19 different beaches.
By Josh Jackett and Kevin Elliott
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Observers noted the hot and bright summer brought on increased growth of some weeds in certain lakes, greater growth of algae, and more beach closings, but no fish kills were reported in the lakes area.
Water temperatures influence a lake's ecosystem because they play a role in the water's dissolved oxygen content.
"What you'll see is lower concentrations of dissolved oxygen in the water because warm water holds less oxygen than cold water," said consulting limnologist Wallace Fusilier.
It's normal for lakes in Oakland County to be about 25 degrees Celsius, or about 77 degrees Fahrenheit during summer, according to Fusilier.
"Last summer we were seeing them at 22 and 23 degrees Celsius, so that's considerably cooler (than normal)," he said. "Last year was a cooler year compared to this year, which has been warm.
"(Dissolved oxygen) saturation at 25 degrees Celsius is 8.263 milligrams per liter," he said. "When we get to say 30 degrees, it's 7.559 milligrams per liter, so you can see it's almost one part per milligram less (oxygen in that warmer water)."
While cooler water will hold more oxygen than warm water, Fusilier said the relatively slight water temperature differences between last year and this year will not make an enormous difference on overall water quality.
According to Fusilier, water conditions are likely to be worse when they reach supersaturated oxygen levels because that would usually indicate a large algae bloom in the water or an unusually high number of aquatic plants in a lake.
"What you get (in warm water) is more algae and more weeds because there are some that like warm water," Fusilier said. "There are some that like cold water, too."
Weed harvesters, whose job it is to clean up the weeds in lakes, have encountered mixed findings with regard to aquatic weed growth this summer.
Eric Gleisner, of Inland Lakes Corp., which harvests weeds from 15 Oakland County lakes — many of which have weed harvesting conducted twice and three times a year — said he didn't notice too much more weed growth this season, but speculated on why it could look like there was or why algae grew more this year than last year.
"Some of it's perception. When the water level drops it looks like there's more weed growth," he said, noting that winter snow melt increases lake levels in the spring. "The other two reasons would be a huge amount of fertilizer run-off, and then the third would be improper use of herbicides in lakes, like a whole-lake treatment.
"If you do whole-lake treatments, you can implode the lake, and lose the dissolved oxygen levels at the bottom of the lake, and you cause this massive nutrient amount to form in both the hydrosoil and the water column, and the algae goes crazy."
Gleisner mechanically harvests lake weeds using machines similar to farm combines mounted on barges that are paddle-operated from each side. They're agile and can move around like a bulldozer or a Bobcat. A front table goes down under the water with a sickle bar and live bed conveyor, which cuts weeds down to a depth of five feet and removes the weed clippings from the water.
"The entire biomass of weeds in freshwater grows in the upper five feet to the sunlight," he said. "Below that is generally a stem. Weeds only really grow in 8 to 13 feet of freshwater. They're not a nuisance below that level."
Bob Pillotson, of Midwest Marine in Milford, which harvests weeds from 18 lakes in northern Oakland County and parts of Washtenaw and Livingston Counties, agreed that there are other factors in addition to warm water involved in aquatic weed growth.
"A lot of the lakes I do are private, non-zebra mussel lakes. In the experience I've had this summer, those lakes aren't really that bad, but on some of the zebra mussel lakes I've done, it's been extrememly bad," he said of weed growth this summer. "It's been pretty dry this summer, so if you don't get a lot of water in your lake, the weeds will grow faster."
Gleisner said zebra mussels clean up a problem that man created and only nature can take care of.
"(The mussels) filter out the planktonic algae that nobody can do anything with," he said. "They're taking care of one problem and creating another by making the water clarity better, and that makes the weeds grow more."
Aquatic herbicide applicator Dick Pinnagle, who serves as president of the Michigan Aquatic Managers Association, said he and other herbicide applicators have stepped up some applications this year; however, treatments have remained fairly level in 2005.
Additionally, Pinnagle said applicators are aware that herbicide treatments may have some negative effects if overused in warmer water.
"(We've had) more surface algae and chara algae treatments this year," Pinnagle said, "but not so much for milfoil.
"There are certain treatments that you can put in the water that have more of a time release aspect to them and don't provide such an initial hard hit as compared to other things. With the things that we put in that could potentially provide a quicker hit, we are backing those down or rotating treatment areas since the potential for fish kills has been heightened because of the warm temperatures. That's the main issue."
While Pinnagle noted some algae has been more noticeable this summer, he said heavy rain events in August helped to limit its growth by chipping away at it.
"It beats it up, but at the same time, it also washes new nutrients back into these lakes, so as soon as the rain stops and the sun is back out, you sort of get that flush again."
Aquest Corp. Limnologist Doug Pullman, who works as a consultant for herbicide companies, also said there seems to be more of some types of algae in lakes this summer.
"The algae really seem a lot heavier this year than in may years," Pullman said. "I think more than anything, we have probably seen fewer (herbicide) treatments because of the high water temperatures and the fear of fish kills.
"It's really hard to say that the algae is a lot worse. I don't have any solid proof, but it sure seems like it."
Pillotson added that at one lake he harvests weeds from, he encountered a type of growth he's never seen before.
"It was like a thorny naiead. It was terrible," he said. "It looked like it was something that would cut you if you walked on it. It grows down on the bottom with the chara; it doesn't grow up. It was all over, mixed in with the chara, which grows everywhere."
Pullman said that the appearance of more algae in some lakes may actually be suspended sediments in the water caused by increased boat traffic.
"I've been on a couple of lakes where there hasn't been algae in the water column but things are really stirred up from the boats," he said. "It may be algae in some places, but it may also just be suspended sediments from the boats."
Some aquatic weeds are also thriving in the warm water and growing faster and thinker than riparians are used to, but one weed that probably didn't fare too well this summer is Eurasian watermilfoil. Since it's a cold weather perennial, Pullman said its production is down significantly in a lot of lakes because the water is so warm.
"The only thing that really astounds me is that we haven't had more fish kills," Pullman said. "I haven't had any more calls than normal, but with such high water temperatures, that would be a logical thing to occur.
"When it all shakes out, it (was) just really, really hot out there."
While many people using the lakes for recreation may have noticed warmer water this year in Oakland County's lakes, the overall temperature of a lake was less likely to be much higher than normal.
"You have to remember that this warm water is only near the surface, and it doesn't go down very far," Fusilier said, adding that the top layer of warm water probably doesn't go down much more than about 15 feet below the surface in most inland lakes.
"Then it starts to get colder and there's that layer of water in there called the thermocline where the temperature changes rapidly with depth," he said. "Usually by about 22 feet, it's cold."
The thermocline, with its cooler water, is normally rich in oxygen, while the water below the thermocline is even colder and typically holds less oxygen. If the top and bottom layers of a lake are low in dissolved oxygen, which fish need to survive, the middle layer usually provides a safe haven for fish.
The relatively stable thermocline may be one of the reasons that biologists at the Michigan Department of Natural Resources (DNR) are not seeing many fish kills this year, despite the higher water temperatures near the surface.
"We haven't seen anything dramatic," said DNR Fisheries Biologist Jim Francis. "Sometimes we can see fish kills or something along those lines. (Warm water and low oxygen levels) can stress the fish out, but typically we don't see it where it stresses the fish to the point of mortality.
"Typically, when we see fish kills, it's kind of sporadic. It can hit some lakes, but we don't get a fish kill throughout a county or region. Each lake is a little bit different, but it's not uncommon when we have a string of 90-degree-plus days that we'll get one or two reports of some fish dying off in a particular lake."
As with some plants and algae, some fish are more likely to experience increased growth when exposed to warmer water. However, increased stress from water temperatures can also stunt a fish's growth.
"There's no question that in warmer water you can grow a fish faster and bigger, but there's also a limit," Francis said. "Once it gets too warm, you're putting additional stress on the fish, and it can actually retard the growth."
According to Francis, the DNR surveys a number of lakes throughout the year. Surveys typically include recording the water temperature and the chemical makeup of a lake. The only lake in Oakland County scheduled to be included in the DNR's survey this year is Big Lake in Springfield Township.
Limnologists typically measure an inland's lake temperature by beginning at the deepest part of a lake and using a probe to measrue temperature and dissolved oxygen. Measurements are usually taken from the surface to the bottom in 1 foot increments.
"Most fish can get in that cooler middle layer where there is still oxygen," Francis said. "Once you get down in the bottom layer, it's the coldest, but ... there's no oxygen so the fish don't do well down there. In the middle layer, the thermocline, they can typcially get in there and get the cooler water temperatures and there's still sufficient (oxygen) for them."
He said, however, that the surface waters probably don't have much of an impact on fishes' overall health.
"Surface temperature isn't necessarily an important thing because fish typically can find some temperature refuge," he said. "From a fish standpoint, I don't think (the summer's warm water is) making a huge difference."
But, while Francis said fish mortality may not be impacted to a great extent, the warm water has influenced fish behavior.
"Typically, the water is cold in early spring and as the spring progresses the water warms up," he said. "How quickly it warms depends on how fast the (air) temperature rises. What we saw this year is that the lakes were kind of cool for a while, and when the heat hit, it hit all at once, so I know the fish earlier in the year were kind of screwed up.
"I know some of them were caught off guard because there are a number of factors that determine when a fish spawns. Part of it's day length, but a major factor is water temperature."
Francis said many fish were waiting to spawn because the water earlier in the spring was too cool. When the temperatures suddenly shot up, many fish had failed to spawn and continued to hold their eggs because the water became too warm.
"We got reports in the middle of July that there were still fish that had eggs, which is way late. I think they were at the point of 'what do we do? Do we drop our eggs now or do we wait for the temperature?'"
While the heat may have caused weeds and wildlife to behave a bit different this year, people continue to be predictable: when the weather is hot, lots of people go to the beach. However, an increase in water temperatures may also mean an increase in bacteria, organisms that love warm water.
According to the Oakland County Health Division, several beaches the department monitored had to be closed because of unsafe levels of those warm-water-loving organisms.
The Oakland County Health Division's Environmental Health Services unit monitors about a third of the nearly 400 public and semi-public beaches in the county each year to determine if they are safe for swimmers. The program runs from June until the middle of August each year.
The department's monitoring program tests about 100 beaches every summer, with priority given to commercial and government-owned beaches, such as those at state, county and municipal parks.
Monitored beaches are to meet a one-day standard of no more than 300 bacteria colonies per 100 ml of water, and a 30-day geometric average standard of no more than 130 colonies per 100 ml. Beaches where water samples exceed those bacteria standards are closed until additional testing shows bacteria levels have dropped.
E. coli has become the target of beach water monitoring programs because it's an indicator of more harmful bacteria. Fecal coliform — the formerly used indicator — suggests a wide variety of bacteria that may not be especially harmful to humans.
Exposure to high levels of bacteria can cause such ailments as ear and eye infections, vomiting and other symptoms. Most recreational water illnesses are spread by swallowing, breathing or having contact with contaminated water.
Mark Hansell, the Health Division's environmental health services unit supervisor, said while high water temperatures may help promote bacteria, the two main factors that foster high bacteria levels in beach water are waterfowl and heavy rainfall.
The total number of Oakland County beach closings this past summer totaled 30 at 21 different beaches countywide, some for a period of multiple days.
The Health Department ordered 26 beach closings in 2004 at 19 different beaches.
By Josh Jackett and Kevin Elliott
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