{"id":223,"date":"2015-04-25T11:16:44","date_gmt":"2015-04-25T11:16:44","guid":{"rendered":"http:\/\/artsci.case.edu\/magazine\/?p=223"},"modified":"2017-02-09T11:23:04","modified_gmt":"2017-02-09T16:23:04","slug":"figuring-out-the-lake","status":"publish","type":"post","link":"https:\/\/artsci.case.edu\/magazine\/2015\/figuring-out-the-lake\/","title":{"rendered":"Figuring out the Lake"},"content":{"rendered":"
\"An

An algal bloom floats alongside a ship in western Lake Erie. Current research focuses on identifying the causes of these harmful blooms and predicting when and where they will appear. Photo by Justin Chaffin.<\/p><\/div>\n

Gerald Matisoff<\/strong> surveyed an expanse of green. It stretched as far as the eye could see, in every direction, like the smooth manicured turf of the world\u2019s largest and most boring golf course\u2014no bunkers or other topographical diversions, no water hazards, no sand traps, no little flags marking the holes.<\/p>\n

But the Case Western Reserve University geologist wasn\u2019t on land when he observed this scene in 2011. Rather, he stood aboard a ship making its way through one of the giant algal blooms that frequently plague Lake Erie\u2019s western basin. \u201cThese mats are very thick,\u201d Matisoff says. \u201cYou don\u2019t see breaks in the algae until the ship passes through. Then you can see the water, but only for a while.\u201d<\/p>\n

People began paying serious attention to Lake Erie\u2019s algal blooms back in the 1960s, alarmed by the unsightly slide of green over blue in parts of the lake and the resulting loss of oxygen, which caused dead fish to pile up on shore. Scientists determined that the algae was thriving on the excess of phosphorus that human activity dumped in the lake, mainly from sewage plants but also from fertilizer runoff from lawns and farms. The United States and Canada joined forces to monitor the lake and regulate some of the pollution, requiring sewage plants to remove phosphorus from wastewater and put it in landfills. This multibillion-dollar remediation helped the sick lake\u2014at one point dubbed \u201cNorth America\u2019s Dead Sea\u201d\u2014gradually return to health by the mid-1980s.<\/p>\n

\u201cFor about ten years, the water quality really improved,\u201d says Matisoff, a professor in the Department of Earth, Environmental and Planetary Sciences, who has been involved in studying and monitoring Lake Erie since he arrived at Case Western Reserve in 1977. \u201cThe fishing was great, and there were no algal blooms. We were rightfully proud of how successful we had been in managing and regulating water quality.\u201d<\/p>\n

The Research Vessel (R\/V) Lake Guardian, operated by the U.S. Environmental Protection Agency, monitors water quality in all of the Great Lakes. When possible, the EPA allows researchers, including Matisoff and his students, time on the ship to conduct their sampling. Photo courtesy of Environmental Protection Agency.<\/p><\/div>\n

From left: Professors Gerald Matisoff and Peter McCall are studying the recycling of phosphorus in Lake Erie\u2014a process that contributes to the formation of toxic algal blooms. Photo by Mike Sands.<\/p><\/div>\n

But in the 1990s, algal blooms reappeared on the lake and have maintained an unwelcome presence ever since. Every year, various types of algae begin blooming in the extreme heat of August. The greatest threat to humans and other mammals comes in September, when parts of the algal mats become dominated by a cyanobacterium\u2014often referred to as blue-green algae\u2014called Microcystis aeruginosa. Microcystis<\/em> has been present in the lake for at least a century but has only reached a nuisance state in recent years\u2014a big problem, since it contains a toxin so virulent for mammals that the military has investigated weaponizing it. In 2014, an intake pipe for Toledo\u2019s water treatment plant sucked up part of an algal mat thick with Mycrocystis<\/em>, and toxins flooded the drinking water. As in the 1960s, Lake Erie\u2019s water-quality problems made headlines around the country.<\/p>\n

That attention has brought renewed interest to the work of Matisoff and other Case Western Reserve scientists, who for decades have been researching the many interacting factors that affect the health of the lake and the creatures that live in it. Policymakers and the public want to know what steps are needed to safeguard drinking water. Many have called for clampdowns on the remaining sources of phosphorus\u2014in particular, farming practices throughout the watershed that allow phosphorus from agricultural chemicals to run into the Maumee River and then into the lake, where it nourishes photosynthesizing organisms like Microcystis.<\/em><\/p>\n

Matisoff\u2019s students insert a plastic tube into a gravity corer, an instrument used to collect sediment cores. A 1-meter core may contain a sediment record that extends as far back as several hundred years. In longer cores, the record may extend as far back as several thousand years. Photo by Gerald Matisoff.<\/p><\/div>\n

Matisoff\u2019s research is of particular interest to the legislators debating regulations. \u201cIt\u2019s very expensive to put in controls and regulate discharges,\u201d he explains. \u201cI\u2019m trying to figure out whether cutting back the amount of new phosphorus being dumped into the lake will solve the problem. And if we do cut back, how long will it take before we see improvement?\u201d<\/p>\n

Matisoff is approaching this question by investigating the continuing impact of the phosphorus already in the lake. Part of the trouble, he says, is that this phosphorus is being recycled. When dead algae and other organic material float down to the lake bottom, they are eaten by organisms living in the sediments. This biological action releases the phosphorus contained in the decomposing matter, making it available to new algal blooms. For this reason, cutting off external sources of phosphorus won\u2019t immediately make the blooms disappear.<\/p>\n

A Picture of Human Impact<\/h3>\n

Those who live along Lake Erie\u2019s shores and venture onto its waters know that it is changeable\u2014sunny and smooth one hour, whipped by waves the next\u2014but no one appreciates its complexity as much as the scientists trying to figure out its secrets.<\/p>\n

Lake Erie is a puddle the size of New Jersey lying atop mud and sand, glacial debris and a basement layer of 400 million-year-old limestone and sandstone. Most of us don\u2019t give much thought to that layer, or to lake and ocean floors in general. And yet, taken together, they are the largest geological feature on Earth. \u201cIt\u2019s the biggest habitat on the planet and the best preserved,\u201d says Professor Peter McCall<\/strong>, one of Matisoff\u2019s department colleagues and director of the Environmental Studies Program. McCall studies the influence that tiny creatures living on the lake bottom have on water quality.<\/p>\n

This habitat\u2019s ancient history\u2014and the light it sheds on the lake\u2019s present condition\u2014is the concern of Associate Professor Beverly Saylor<\/strong>, a specialist in stratigraphy and sedimentology. When she first joined the faculty in 1998, Saylor began probing the evolution of Lake Erie since the last ice age. She carried out her early work in collaboration with Enriqueta Barrera<\/strong> (GRS \u201980, \u201983, \u201987), then a professor at the University of Akron and now a program director at the National Science Foundation.<\/p>\n

Saylor\u2019s first foray to collect data from Lake Erie\u2019s distant past occurred in 2002, when she and some students boarded the Canadian Coast Guard ship Limnos and sailed off to collect piston cores\u2014sediment samples extracted from the lake bottom with long tubes. It was a queasy trip for the then-pregnant Saylor, but a successful one. By now, she has taken two more trips and amassed a collection of ten cores, including one from the lake\u2019s central basin, near Cleveland, that is 32 feet long and dates back 7,000 years.<\/p>\n

\u201cThese cores are like history books that go way, way back,\u201d Saylor says. \u201cWe can use them to look at the magnitude and timescale of natural variations in the lake without the impact of humans. That allows us to have a clearer picture of human impact.\u201d<\/p>\n

Geological history traces one cause of the lake\u2019s current water-quality problems. When the glaciers that carved out the Great Lakes receded 10,000 years ago, Lake Erie wasn\u2019t connected, as it is now, to Lake Huron, through the Detroit River, or to Lake Ontario, through the Niagara River. However, as the weight of all that ice disappeared, the land mass gradually rose again over a period of 5,000 years. This shift opened Lake Erie\u2019s connections to the two other lakes, and it caused irregularities in the lake\u2019s depth. As a result, Lake Erie is really three different lakes, with average depths of 24 feet in the shallow western basin, 60 feet in the central basin, and 80 feet in the eastern basin.<\/p>\n

These variations set the stage for the chronic problem of anoxia\u2014the absence of oxygen\u2014that plagues Lake Erie\u2019s central basin today.<\/p>\n

Graduate student Mary Carson collects suspended sediment from the Ashtabula River, a Lake Erie tributary. The collected sediment is later analyzed in a lab at CWRU to provide information about the chemicals the river delivers to the lake. Photo by Gerald Matisoff.<\/p><\/div>\n

Anoxia isn\u2019t an issue in the winter; when the oxygen-rich surface waters are cold, they mix readily with the cold waters below. But once the surface water begins to heat up in the spring, it loses density and doesn\u2019t mix as readily with the denser cold water beneath it, so new oxygen isn\u2019t introduced at depth. At the same time, warmer temperatures overall prompt greater activity among the billions of tiny creatures living at the bottom of the lake\u2014including bacteria busily decomposing organic material such as algae, which blooms in the western basin, blows eastward, dies and drifts to the lake floor. Since all those creatures require oxygen, their increased activity as the summer begins removes oxygen from the deeper waters.<\/p>\n

Thermal stratification goes on all over the lake. But it\u2019s not a problem in the western basin, which is so shallow that the upper and lower layers of water mix when the wind blows and keep the deeper waters oxygenated. And it\u2019s not a problem in the eastern basin, because the depth holds such an immense volume of water that the creatures at the bottom can\u2019t burn through all the oxygen it contains. \u201cThe central basin is this special zone that\u2019s always on the edge,\u201d Saylor says. \u201cOther factors can push it over that edge into anoxia.\u201d<\/p>\n

Anoxia can be a death sentence for many of the fish and for the tiny organisms living in sediments on the lake floor. But that is not the only danger it poses. Oxygen acts as a lid on toxins and other materials held in those sediments. \u201cWhen these deeper waters lose oxygen, the toxins can flow into the overhead water,\u201d McCall says. \u201cThe highway to the rest of the lake widens.\u201d<\/p>\n

Eliza Kaltenberg, a graduate student in the Department of Earth, Environmental and Planetary Sciences, carries a trap for suspended sediment from the lab on the R\/V Lake Guardian to the back deck for deployment. Photo by Mary Carson.<\/p><\/div>\n

Figuring out all the factors that create anoxia, and<\/em> figuring out how all the different water-quality issues affect each other, is a huge task. That\u2019s because Lake Erie\u2014the shallowest of the Great Lakes, and the smallest by volume\u2014is the most dynamic and changeable member of that watery quintet. Its waters recycle every three years.<\/p>\n

\u201cAnything humans do or nature does is quickly reflected in the lake,\u201d Matisoff says. \u201cWe have to tease out so many factors, including natural weather variations\u2014changes in temperature or wind, or the timing of storms relative to when farmers are planting their crops. You reach a conclusion and think you understand the impact of one of those factors. Then something changes and the whole lake is different, and you have to rethink.\u201d<\/p>\n

Mud Matters<\/h3>\n

While the waters of Lake Erie recycle rapidly, the muddy environment at the bottom is much more stable. Matisoff first developed an interest in this mud and its contents when he began studying sediments that the Army Corps of Engineers dredged from the Cuyahoga River and dumped in the open lake. Matisoff and McCall examined how contaminants in these sediments circulated into and out of three-and-a-half feet of mud on the lake floor.<\/p>\n

Tyler Steube, a field station assistant for The Ohio State University\u2019s Stone Laboratory, assists divers in the deployment of a bottom chamber designed by Gerald Matisoff. Water samples collected from the bottom chambers provide important information about the internal recycling of phosphorus and other materials that impact the water quality of the lake. Photo courtesy of Stone Lab.<\/p><\/div>\n

This early work led naturally to studying the circulation of phosphorus. In one investigation last summer, Matisoff deployed contraptions of his own design on the lake floor to see how much of the lake\u2019s phosphorus was seeping out of the mud. He carried out this research as a participant in the Great Lakes Restoration Initiative, a $500,000 project funded by the U.S. Environmental Protection Agency and administered by the Ohio EPA\u2019s Lake Erie Commission. In addition to Matisoff and students from his department, the project includes scientists from The Ohio State University\u2019s Stone Laboratory, the University of Toledo, Heidelberg University, the U.S. Geological Survey and a private consulting firm.<\/p>\n

Stephanie Hummel (CWR \u201914) sets up an experiment to determine the amount of phosphorus released when bottom sediments are resuspended in the lake. Photo by Gerald Matisoff.<\/p><\/div>\n

Matisoff\u2019s preliminary findings suggest that about half of the phosphorus igniting the lake\u2019s algal blooms comes from the sediments. McCall\u2019s ongoing work provides details about this process. Early in his career, McCall learned to scuba dive so that he could conduct his research on the mud floors of lakes and oceans\u2014an often mucky situation, since disturbing the sediment can reduce visibility from 12 feet to six inches. \u201cI could have studied coral reefs and been able to see!\u201d McCall jokes. \u201cThis was like working in a closet.\u201d<\/p>\n

With more than 1,000 hours of diving behind him, McCall has finally hung up his scuba gear. Now he concentrates on experiments in his lab. In one, he sets up environments that look and function like ant farms, six inches across and a foot tall, filled with mud and water and organisms, most of them microscopic.<\/p>\n

\u201cThe little things living at the bottom are major actors in the flow of materials that are important to humans,\u201d McCall says. \u201cLittle things run the world! Most geoscientists prefer to ignore them, but if your models don\u2019t include the action of these organisms, you\u2019re likely to be in error by a factor of two to ten.\u201d<\/p>\n

Matisoff is combining new data about the impact of these tiny creatures, and about the circulation of phosphorus in and out of the sediments, with other data in a complex computer model that generates predictions about the lake\u2019s water quality. For instance, the model predicts when and where problems like algal mats might occur and what factors might abate them.<\/p>\n

So far, his calculations don\u2019t provide simple answers for lakeside dwellers who want to prevent the recurrence of the algal blooms. Even if people take steps to stop the flow of new phosphorus from farming operations along the Maumee and Sandusky Rivers, it will take time\u2014perhaps 10 to 15 years\u2014to reduce overall phosphorus levels to the point where the blooms completely stop. There\u2019s no easy fix.<\/p>\n

\u201cIt\u2019s a challenge to figure out this lake!\u201d Matisoff says. \u201cIt\u2019s a challenge we like, but it\u2019s difficult.\u201d<\/p>\n

Science writer Kristin Ohlson is the author, most recently, of <\/em>The Soil Will Save Us: How Scientists, Farmers, and Foodies Are Healing the Soil to Save the Planet.<\/strong><\/p>\n

\n

DISRUPTING THE FOOD CHAIN<\/h3>\n
\"Joseph

Joseph Koonce, professor emeritus in the Department of Biology, began studying Lake Erie’s fisheries in the 1970s. Photo by Daniel Milner.<\/p><\/div>\n

Like all nutrients, phosphorus isn\u2019t necessarily a bad thing. Without the historic surges of phosphorus from the wetlands that once surrounded Lake Erie\u2019s western basin, the lake would not have become the tremendously rich fishery that led Native Americans and Europeans to cluster along its shore. Even now, Lake Erie\u2019s\u00a0sport\u00a0and commercial fishery is worth well over a billion dollars annually.<\/p>\n

\u201cWetlands add a lot of organic material,\u201d says Joseph Koonce<\/strong>, professor emeritus in the Department of Biology. \u201cIf you look at the most productive fisheries in the world, they\u2019re all associated with estuaries. At one time, Lake Erie was sturgeon heaven because of that high productivity.\u201d<\/p>\n

But when Koonce began studying Lake Erie in the 1970s, the sturgeon and the wetlands\u2014by then replaced with farmland\u2014were long gone. Alarmingly, the walleye, one of the lake\u2019s other great delicacies, was also in precipitous decline. Koonce and others started examining the many factors affecting the decline and plugged data into large-scale ecosystem models. Recovery strategies followed. By the 1980s, the walleye were back in force and Lake Erie was the walleye fishing capital of the world.<\/p>\n

Weirdly enough, however, that resurgence may have opened the door to the invasion of the infamous zebra mussel. This freshwater mussel from Russia likely entered the lake through illegally dumped ballast water from oceangoing ships. Though the zebras were probably introduced many times before, conditions in the lake during the 1980s were ripe for their rapid expansion.<\/p>\n

When the numbers of walleye\u2014a powerful predator at the top of the food chain\u2014swelled, they decimated the population of the lake\u2019s prey fish. These smaller fish feed on zooplankton and other tiny creatures in and around the algae, including zebra mussels when they\u2019re in their larval stage. So there was nothing to brake the growth of the zebra mussel population. \u201cThat\u2019s the perverse thing,\u201d Koonce says. \u201cRight when the zebras invaded, there were very few of these small fish to consume them.\u201d<\/p>\n

The zebra mussels went on to disrupt the food chain in the lake, adversely affecting everything from worms living in the sediments to fish. Some scientists also suspect that the zebra mussels\u2019 feeding habits hasten the deposition of phosphorus on the bottom of the lake and contribute to its recycling.<\/p>\n

Since Koonce retired from the faculty in 2012, his research has taken him far from the lake to study how land-water interactions throughout the greater watershed work their way down to Lake Erie. \u201cMosaics of biological features act to shape the overall landscape and affect things like runoff,\u201d he says. As part of this watershed focus, he\u2019s become involved with the Cleveland Botanical Garden’s Vacant to Vibrant research program. The program repurposes vacant urban parcels by installing soil and vegetation\u2014”green infrastructure”\u2014to control runoff.<\/p>\n

Koonce also thinks a lot about how climate change is affecting the lake. \u201cClimate change is a wild card, and it\u00a0has the potential to make the lake\u2019s condition worse,\u201d he says. “But with no political consensus on the existence of the problem, it\u2019s difficult to plan for that.\u201d<\/p><\/blockquote>\n

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Gerald Matisoff<\/strong> surveyed an expanse of green. It stretched as far as the eye could see, in every direction, like the smooth manicured turf of the world\u2019s largest and most boring golf course\u2014no bunkers or other topographical diversions, no water hazards, no sand traps, no little flags marking the holes. …Read more.<\/a><\/p>\n","protected":false},"author":97,"featured_media":377,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[22],"tags":[],"acf":[],"jetpack_featured_media_url":"https:\/\/artscimedia.case.edu\/wp-content\/uploads\/sites\/147\/2015\/04\/14220143\/MarySedimentTrap_toc.jpg","_links":{"self":[{"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/posts\/223"}],"collection":[{"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/users\/97"}],"replies":[{"embeddable":true,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/comments?post=223"}],"version-history":[{"count":10,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/posts\/223\/revisions"}],"predecessor-version":[{"id":1876,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/posts\/223\/revisions\/1876"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/media\/377"}],"wp:attachment":[{"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/media?parent=223"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/categories?post=223"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/artsci.case.edu\/magazine\/wp-json\/wp\/v2\/tags?post=223"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}