Articles on nature and the natural history of the Grand Traverse Region. From descriptions of geological strata or animals and plants of the Great Lakes states to nature walks and gardens of the region, this feature covers everything in the great outdoors.
We have all seen them, but we haven’t given them names: a swarm of tiny insects flying in a crowded formation often looking like a column. Certainly, it is much taller than wide, its width usually not more than a foot or two at most, its height often taller than we are. Our fear is that the insects will bite us, or, at the very least, we might inhale them. Unlike birds and bats, we do not relish them either for flavor or for nourishment. We steer clear of them and go about our business.
Midge swarms form in summer and early fall. The insects comprising them do not bite, though that passivity is often not enough to keep humans from spraying poisons on them. They transform from aquatic larvae, tiny forms resembling segmented worms, ready to mate upon emerging from their pupal cases, but not ready to eat since they do not possess the required mouthparts. So it is they do not harm us.
Most members of the swarm are male: they seek to mate with females that pass through the mass of flying insects. Upon being fertilized, the female will set about to lay eggs in the waters of ponds and ditches. Several broods are produced during the year with the last overwintering in mud underneath the ice.
According to Donald W. Stokes, author of A Guide to Observing Insect Lives, midge swarms are often found close to water, often above prominent features called “swarm markers.” These can be patches of light or dark on the ground, or high points such as the upthrust branches of a shrub or tree—or even the top of your own head! A shiny black piece of plastic will attract a certain species, if one wishes to try an experiment.
Swarms may form in the morning, evening, or even mid-day, depending on the species. Considering that the insects do not live for more than a couple of days, the observer cannot count on a week of entertainment. New broods, though, will prolong the joy of avid midge watchers.
Stokes notes that, in a wind, the midges face in one direction and move forward to the limit of the swarm marker and back, the effect making it look like the entire swarm is dancing. The resulting shimmy captures the interest of naturalists everywhere. Unsurprisingly—given their awareness of nature, the Japanese haiku poets have written about the swarms (which they call “mosquito (or midge)) columns:
Across the mosquito columns Hangs the floating bridge Of my dreams.
The mosquito columns, Big and thick As of a palace
The Capitol Is visible through a hole In the pillar of mosquitoes
(translations courtesy of R. H. Blythe)
The poets often portray the fleeting lives of mosquitoes (midges) as emblematic of the fleeting existence of things we imagine to be great and eternal, things like palaces and the Capitol (Kyoto). That is what we should take away from our experiences with midge swarms: the beauty and wonder of ephemeral things that live out lives unnoticed by us all.
How many times has it happened? Along East Bay, usually at night or early morning, the water surges up, rising four feet or more from its normal level, only to subside within minutes.In the past, roads have been flooded, docks floated away, and debris swept into the water.Houses and cottages have been flooded and cars damaged by the flooding such that they had to be towed away for repair.West Bay gets them, too, but East Bay, especially at the south end, from Five Mile road west to the Birchwood area of Traverse City have been especially hard-hit.
The 1950’s experienced a number of these events, not just locally, but throughout all the Great Lakes.At first, no one knew what to make of them: newspapers called them “Tidal Waves,” often using quotation marks since everyone knew they had nothing to do with the tides.The only similarity is that the water rose somewhat gradually, and not with an abrupt crash of giant waves on the shore.In 1952, the Traverse City Record Eagle declared no one knew what caused them, but that observation was soon to change: a surge of water with immense waves swept up on the Chicago shore on June 26, 1954, causing the deaths of ten persons.That tragedy sparked interest among scientists studying the phenomenon.They would soon uncover the causes.
Gordon E. Dunn, Meteorologist-in-charge of the Chicago office, realized that, on past occasions, the surges always occurred after the arrival of a pressure increase associated with a rapidly moving storm front coming from the north.On July 6, 1954, just ten days after the devastating surge described above, conditions looked nearly identical to those of that day.Based upon his understanding of the event, Dunn issued the first seiche warning. Somewhat to his surprise given his scant knowledge, a moderate seiche did strike Chicago, one that caused little damage, much to the relief of all.
Since those early times, we have learned much more about seiches.They are associated with fast-moving storm lines, especially those moving faster than 50km/hr.There must be a significant pressure rise associated with those lines, with a long fetch of water covering the entire width of a body of water—Lake Michigan or Grand Traverse Bay–making for more the most dramatic events.One factor Dunn did not understand was the most fundamental thing of all: storm surges bounce off shores and send reflected waves outward to interact with those coming in.It is like a basin of water with a water disturbance that reflects off the sides, sometimes building into surges that are magnified by the coming together of different waves.Surges and the receding of water can go on for days as waves interact, just as water in a basin takes time to settle if it is disturbed.All of this happens during seiches.
East Bay presents another aspect of seiches.It has vast shoals—shallow areas—that extend from the south and west shores.When rising water strikes them, waves grow taller, driving farther inland.One of the descriptions of a seiche claims that the water rushed 30 to 40 feet inland from its usual position, but only in areas at the base of the Bay.This “shoaling” effect is known to increase the severity of seiches.
East Bay also presents an obstructed range of open water (a “fetch”) that enables waves free travel down its length.By contrast, West Bay has a narrowing at Lee’s Point on the west side and Bower’s Harbor on the east, after which it widens at the south end.Contours of the land also affect the severity of seiches, and East Bay seems especially suited to maximize high water surges.
This is not to say West Bay has not experienced them.On April 1, 1946, a resident of Bay Street in Traverse City reported the water level rose two feet before subsiding.An older story is told that in March, 1891, the city had been withdrawing water from West Bay for household use by means of an intake pipe that extended two hundred feet from the shore under twenty feet of water.When the pumps started racing one morning, it was realized that no water was being moved at all.Upon breaking the ice that covered the intake, it was discovered that the water had receded to the point that the mouth of the pipe wasn’t in the water at all.Soon after, water levels rose, and residents were able to get water for their morning coffee.The peculiarity of this event—occurring when the Bay was frozen—sets one to wondering if some factor besides a seiche wasn’t operating.
East Bay experienced three significant seiches in the two years 1952-53.The May 5, 1952 seiche is interesting because we have access to hour-by-hour data about wind speed and direction.Hour-by-hour after midnight the wind direction changed: 1:00 AM: out of the East at 7 mph; 2:00 AM: out of the west at 7 mph; 3:00 AM: out of the south at 10 mph: 4:00 AM: out of the west at 8 mph; 5:00 AM: out of the north at 12 mph.The wind direction stayed out of the north after that time for the rest of the day. Note the time of day: after midnight and early morning.For reasons not completely understood, the biggest surges of water tend to happen in early morning up to noon.Also note that the wind direction jumps from one direction to another, finally ending with a strong wind out of the north.The effect is to pile up water on one side of the Bay, only to have it rush in from the north.Given the contours of that body of water, that is exactly what you would expect in order for the biggest surge of water to occur at the southern end.
Residents on the south shore of East Bay notified the sheriff of the flooding shortly after 4:00 AM, a time fairly consistent with the wind change out of the north.After the first surge, water rose again and again, but never reached the high water mark of the first rush.That behavior goes along with our present understanding of seiches as disturbances in a closed basin with waves that reinforce each other at times.
When will the next seiche be?Who can say?We should beware when a fast-moving storm line moves in from the north associated with rapidly rising air pressure.The National Weather Service now issues warnings when conditions are favorable for water surges and high waves, and persons living in vulnerable places should take precautions to protect their lives and property. It has been some time since the last big one and it is easy to become complacent in the absence of memory.After all, Nature acts whether we are ready or not for what she gives us.
A sponge is the antithesis of a super hero.It stays in place, sifting out plankton (microscopic algae and animals) from the water that passes through its body.Its body is not of great interest, lacking appendages altogether, not even possessing tentacles that might enwrap evildoers and others that would do it harm.Its personality is not engaging, either, since it does not have a brain.
To get its food, it has many small openings that take in its tiny prey, and a few larger ones that expel the water it has cleansed.The pumping system that carries on the circulation is primitive: cells with tiny whip-like appendages (flagella) line passageways, setting up the current.There are no robust hearts in sponges.
A simple animal reproduces simply.In some species of sponge, balls of cells (gemmules) form in mid- to late summer that can break off from the parent animal and grow into a new sponge somewhere else.This asexual form of reproduction is perhaps the most common means of making new sponges. However, sperms and eggs can be made inside its body, those fertilizing each other in a display that has nothing to do with affection.You wonder, without courtship, without males showing off what they’ve got, what is the point of reproduction like that?
Sponges do have a skeleton of sorts, however.In the ocean, some of them have a soft one made up of spongin, a substance that becomes flexible and absorbent upon being rehydrated.Those sponges have been used for hundreds of years in the Mediterranean Sea and elsewhere for scrubbing everything from floors to human bodies.Mostly replaced by plastic substitutes, they are occasionally used today.
Many years ago I took a course in invertebrates at the University of Michigan’s Biological Station at Pellston, Michigan, and was surprised to learn that we have a freshwater sponge that inhabits our lakes: Spongilla lacustris (a few other species can be found here, too).As I observed it, its body most often was in the form of a greenish blob attached to sticks or pondweed–the green color, I found out, came from algae inhabiting the animal. It was not at all gooey or gelatinous, but felt rough to the touch and a bit like glassy bits stuck together when dried.Unlike its ocean brethren with its spongin, it had a skeleton made of crystal-like tiny elements made of silica, the same stuff that comprises most of our sand in Northern Michigan.
At least one animal appreciates Spongilla–but not for its appearance or life habits. Spongilla fly larvae feed on it with zest, later pupating to become small flies we are certain to ignore among the multitude of other flies that hatch in lakes and ponds. No life form–not even the sponge–is too humble to escape predators.
Spongilla is very particular about where it lives: it must have the cleanest, purest water around.For that reason, it is considered to be an indicator of pristine, unpolluted lakes.Far from being a pestilence, freshwater sponges are a gift.We should not condemn them for what they are not—gifted superheroes of the animal world.They are not delicious, not cute, not pretty, but they do constitute a component of our most treasured biological communities, the clear lakes that grace our landscape in Northern Michigan.Let us rejoice in their presence here.
Milk snakes do not milk cows, contrary to legend. They do hang around barns and other structures–sometimes houses. Someone I know shares her dwelling with occasional milk snake intruders which apparently enjoy living in the crevices of the foundation. It does little good to let her know that they are only looking for rodents and other small varmints—she does not like them. To her credit, they have become only an occasional nuisance, and are only evicted from the premises rather than summarily decapitated, a common response of humans.
I saw one quite recently, three feet of torpid elegance stretched across a bike path near where I live. Fearing for its life–since it nearly blocked the right-of-way of bicycles–I stamped on the ground to get its attention. With apparent nonchalance, it moved to one side and then into the tall grasses beside the river, its tongue flicking out every few seconds as snakes do.
Indeed, why do they do that? Reference books tell me that this is their sense of smell, but that statement is not quite accurate, since the actual organ of smell is inside their mouths. The tongue only samples the air outside. Since they don’t bring air directly past their olfactory membranes, then they can only smell whatever comes to them on the wind, a strange mechanism at least from our point of view, since we can sniff. What smells would they be sensitive to? Rodents, one might guess, and other milk snakes, females especially–if a male snake is the prime actor.
Milk snakes are harmless, but that does not mean they will not attempt to discourage those who would cause it irritation. Like many of its relatives, it will coil, hiss, and strike to incite fear in the hearts of its perceived enemies. It should be forgiven for that behavior, not beheaded.
These creatures are most commonly seen in spring and fall. They go after their prey after nightfall, seeking out mice with their flicking tongues, ready to wrap themselves around them in an instant, squeezing them so they cannot breathe. That is what constrictors do.
Milk snakes are given the name Lampropeltis triangulum triangulum, the “triangulum” element referring to a triangle or Y-shaped marking at the top of its head. In larger snakes dull red bands decorate its body, but smaller ones will have brighter red stripes bordered with black, all set upon a creamy white background.
After your initial surprise at seeing one, you will have to admire this animal for its stunning appearance. As so many snakes and reptiles are disappearing because of habitat disruption, they are to be treasured all the more. Let us live in peace with them.
Want more on snakes? Check out these TADL books about snakes
Holman, J. Alan, Harding, James H., Hensley, Marvin M., and Dudderar, Glenn R., Michigan Snakes, Lansing: Michigan State University Press, 1993, 2006.
Holman, J. Alan, The Amphibians and Reptiles of Michigan: A Quaternary and Recent Faunal Adventure, Detroit: Wayne State University Press, 2012.
Richard Fidler is co-editor of Grand Traverse Journal.
Poison ivy, poison sumac, poison oak: the three poisons we have to take care not to touch. The third doesn’t grow here, so we don’t need to worry about it. Somewhat rare in Northern Michigan, Poison sumac is a tall shrub that grows in wet places—I have seen it in the Platt River valley, locally. Ed Voss’s magnificent floral guide Michigan Flora shows a cluster of counties with the species: Benzie, Grand Traverse, Leelanau, and Antrim. It is much more common downstate.
Poison sumac will not be confused with other sumacs, the staghorn sumac, for example. That plant has red berries and grows along fields and edges of hardwoods. As a teacher, I sometimes had to quell students’ fears that they would break out from touching staghorn sumac. Unlike that familiar shrub, poison sumac grows in places where you get your feet wet. If it has berries at all, they are white. The leaves have the shiny look of poison ivy, but have 7-11 leaflets. Persons in search of pretty autumn color for their homes may be surprised to learn they brought it into the house.
Poison sumac (Toxicodendron vernix) is closely related to an Asian plant (Toxicodendron vernicifluum) which is used to make lacquer in Japan and elsewhere in Asia. While serving in Japan, a dermatologist friend told me that patients came to him with a rash similar to that of poison ivy on the backs of their thighs. The cause turned out to be toilet seats covered with the offending lacquer.
Poison ivy grows in a variety of plant communities: sand dunes, banks, shores, and along roadsides and railroad tracks. In the north, it does not climb trees, but remains as a small shrub, scarcely growing taller than two feet. Its shiny green leaves are, indeed, in threes (“leaves of three, let them be”), but that characteristic is not at all helpful since strawberry leaves come in threes, too. In contrast to the shrub form, it frequently takes on the growth habit of a vine in Southern Michigan, climbing a variety of trees, often to great height. Manistee county, according to Voss, is the farthest north this variety is to be found.
Are two such radically different varieties—one a shrub and the other a vine—really the same species? In most characteristics—leaf position and shape, length of leaf stems, inflorescence (arrangement of flowers on the stem), number of flowers, fruit size—they are similar, but not identical. The vine form has aerial rootlets to cling onto tree trunks, while the shrub form has none. If they are the same species, they should form intermediate forms upon crossing the two. Have they been crossed to see what the offspring look like?
Unfortunately, my source—William T. Gillis’s article in the Michigan Botanist, Vol. 1, 1962—talks only about one failed attempt. An early frost killed the buds on the growing hybrids. Gillis did attempt to bring the northern rydbergii form to southern Michigan to see if they would begin to take on southern characteristics. They did not.
Let us leave the subject to say that poison ivy is a highly variable plant. One characteristic that all forms have is that they possess urushiol, the offending substance that causes the skin reaction in some persons. It is not volatile, so you cannot get the rash from merely standing close to plants: you must break the resin canals in the leaves in order to be exposed. Once exposed, it may take one or two days to react, or—in some cases—only a few hours, depending on the sensitivity of the person afflicted. Dogs and cats can carry the allergen on their fur, and smoke from burning leaves can cause serious trouble. It can even be carried on water—at least in the case of poison sumac, the species that loves to grow with roots in the water.
Not everyone is sensitive. Some persons can handle leaves and fruit with impunity. However, you cannot always count on previous insensitivity to avoid the rash. Sensitivity can change over time, and in either direction. Steroidal creams and lotions ease the suffering of those afflicted, and the itching and angry blisters will disappear over time. Still, a person will not want to suffer this assault every year. So much the better to learn these plants and avoid them.
by S.A. McFerran, B.A. Environmental Studies, Antioch University
Michigan Attorney General Bill Schuette recently weighed in on aquaculture. His opinion is that aquaculture would subordinate public uses of open waters in favor of private control.
The open waters of Lake Michigan have been used for commercial purposes in the past and are currently used for commercial purposes. Aquaculture is a commercial use, as are marinas and trap nets already in common usage by commercial fishermen. Trap nets are set in the Spring and often remain on the lake bottom until fall. They are checked regularly and the fish are sorted and the nets returned to the lake bottom. A net pen for aquaculture is similar and like a trap net would not interfere with public use of open waters. With proper siting, scale and monitoring, pollution is minimal. (1)
What tools do the architects of an ecosystem have? Add species, subtract species (as with the sea lamprey), improve habitat and change goals. Fishery departments know a lot about the limnology of the lakes. Using that knowledge, places favorable to aquaculture could be identified. Limited operation could be allowed in those places.
A worthy goal is the local production of fish by Michigan citizens in Michigan waters. Just as enthusiastic farmers sell vegetables at local markets, small aquaculture operations could offer fresh local fish at market. Large corporate fish operations should not be the goal. The goal is a citizen-led entrepreneurial process that allows aquaculture on a local basis.
If government is making a determination on how many fish can be raised in the Great Lakes, it would be informative to know what the historic population of fish was. It is clear to anyone reading historic accounts of fishing in the Great Lakes that the population of fish was, in the past, much greater than it is now. In 1872, 39 million pounds of fish was taken. The total fish population was more than twice the present populations. (2) That alone puts to rest the argument against the resiliency of the Lakes.
Additionally, other technical problems of aquaculture can be solved in Michigan as they are being solved in the rest of the world. (3) The State of Michigan has learned a lot about how to operate aquaculture in places like Platte River. That hatchery was once a big polluter of Platte Lake but they cleaned it up and now raise millions of fish pollution free.
Another local success story concerns Harrietta Hills Trout Farm LLC, on the AuSable River, which has operated for five years without incident. The Department of Environmental Quality issued a permit for the farm that holds the operators to high standards which “requires weekly monitoring for phosphorus, which cannot, on a seasonal average basis, exceed 15 parts-per-billion in the 8.64 million gallons-per-day”. (4)
Ecosystems are complex. In recent history, marketing the experience of catching fish, and sport fishing in general, has subordinated any other possible use of the Lakes, including aquaculture. Both have a place in the Lakes. The Waters held in “public trust” are held for all the “public,” not just sports fishermen.
S.A. McFerran B.A. Environmental Studies, Antioch University Platte River, Michigan
(1) Diana, Jim, quoted from personal correspondence with the author, February 2017. Dr. Jim Diana is Director for Michigan Sea Grant, and is involved in leading the statewide program in its research, education and outreach efforts on critical Great Lakes issues, such as sustainable coastal development and fisheries. When asked about pollution issues, specifically if Aquaculture pens can be operated without polluting the Lakes, his response was: “Absolutely. There are 11 licensed operations in Lake Huron on the Canadian side, and no damages have been determined from them as of recently. There was a problem in one area, with nutrient addition causing some algal blooms, but they moved to another location and all has been fine since.”
(2) Bogue, M.L. Fishing the Great Lakes – An Environmental History. University of Wisconsin Press, 2000.
(3) “On January 11, NOAA published a final rule implementing our nation’s first regional regulatory program for offshore aquaculture in federal waters. In doing so, NOAA is expanding opportunities for U.S. seafood farming in the open ocean. NOAA and our partners are working to advance and expand U.S. aquaculture.” NOAA Fisheries. “NOAA Expands Opportunities for U.S. Aquaculture.” Accessed March 20, 2016. http://www.nmfs.noaa.gov/stories/2016/01/offshore_aq_rule.html
Is aquaculture—growing lots of healthy eating fish inexpensively through fish farming—a great idea? NO! The basic problem with raising many animals in a small space is poop. Large net-pens (fish cages) producing hundreds of thousands of fish will generate untreated fecal waste in huge amounts. This is essentially the same problem with other CAFO’s (Concentrated Animal Feeding Operations)–too many fertilizing agents headed downstream which wind up producing massive toxic algae in larger bodies of water. The Lake Erie and Toledo, OH water pollution disaster of 2014, is a perfect example.
Some have argued in support of aquaculture that the waters of the Great Lakes are a public trust, but that argument, to me, is precisely why aquaculture should not be permitted to pollute these waters. According to Jim Olson, attorney with For Love of Water (FLOW), the waters of the Great Lakes are “a shared public commons for the benefit of citizens for navigation, boating, fishing, health, and sustenance.”
And, according to Dr. Howard Tanner, former Michigan Department of Natural Resources Fisheries director, “…one net-pen operation can produce the equivalent of phosphate emissions from a sewer plant for 10,000 people. This fish sewage will create filamentous algae, which will wash up on nearby beaches and rot and stink.”
Only in self-contained aquaculture facilities can the waste products of the fish be controlled and kept out of the people’s waters downstream.
Another problem with fish farms is the antibiotics used to control disease. Again, the leftovers get flushed down the river or are mixed in with the lake waters and are then consumed by you and me.
Economics are another part of the big picture. Lake Michigan sport and commercial fishing is a billion dollar industry. Aquaculture can’t compare to that in generating jobs or money.
Michigan’s Attorney General Bill Schuette is on the side of protecting the environment. He has ruled that fish farming does not improve the public trust for the uses listed above, and would necessarily interfere with or impair them. Thus, it is illegal in his opinion. He says that fish farming in the Great Lakes does not fall within the definition of “aquaculture facility” under the state aquaculture law, because the definition only allows fish farms in privately controlled waters. Under the Great Lakes Submerged Lands Act as well, it is illegal to “occupy” public waters for primarily private purposes such as fish farming.
So my suggestion is to NOT purchase Rainbow Trout in the supermarket or order it in the restaurant. That is the species usually raised in commercial fish farms. Instead, go fishing in a nearby lake or stream in which trout swim and grow naturally and where it is legal to keep them. Try to catch one or two, yourself. It’s quite enjoyable and they are good for you, too.
About Charlie Weaver
Charlie Weaver is a retired fly fishing river guide on the Au Sable, Manistee, and Pere Marquette rivers. He serves as a board member on the Northern Michigan Environmental Action Council, and belongs to the Anglers of the Au Sable (Adams Chapter of Trout Unlimited) and to the Clearwater Conservation Committee of the Sierra Club.
PO Box 1308 Kalkaska, MI 49646 ctejedor AT copper.net
Why are some trees species eager to leaf out early in spring while others stay dormant until much later?Poplars and maples break dormancy quite early, sometimes before the last frost, while black locust, oaks, and catalpa bide their time, often waiting until late May.Certainly, as with most things in nature, many factors explain the difference, but here I would like to concentrate on one of them: the kind of wood trees make.
Wood is the water-conducting tissue of a plant.Under the microscope it appears to be made up of long, torpedo-shaped cells liberally sprinkled with holes to let water pass through.Wood is mostly made of these cells–called tracheids.Pine trees have no other specialized cells to carry water up the tree, but broadleaf trees do, vessels.
Vessels are not torpedo-shaped at all, but resemble soda straws.You need a microscope to see them, but they are quite large as cells go, and that size can be a drawback.If air bubbles form inside them or ice crystals form in a late spring frost, they can be damaged so that no water goes up to service the expanding leaves.
Trees with large vessels are especially at risk.Just when buds need water from the roots, none is forthcoming.The solution, for such trees as black locust and oaks, is to manufacture a ring of vessels early in spring to carry the water up.The trouble is, it takes time to do so, time which the tree yields to other species that do not have to form a fresh layer of vessels, maples and poplars.That means those species get the jump on those working to make new vessels.Trees that make vessels lose out for a time in the battle for sunlight.
For all that, they are quite successful.Black locusts are “weed trees,” growing rapidly like weeds, whole groves of them joined together with underground rhizomes.A white oak takes a different pathway, putting its energy into growing a single individual.Both trees have a ring of vessels laid down in early spring, a ring clearly visible in the wood’s annual growth rings.They will serve as the major plumbing system until dormancy in the fall.
However, some ring porous trees leaf out early.The explanation, according to one researcher, is evolution: they simply evolved in a warmer climate, spreading later to the North.Science is never straightforward in the answers to questions it provides.
Shrubs leaf out early for a different reason.They need to get as much sun as possible before the large trees expand a dense canopy of leaves above.This year, see if that is not so: Do smaller native shrubs leaf out before the trees of the canopy overhead?
The time of leafing out—budburst some call it—varies according to the year, the habitat, the species, and the weather.Naturally, a warm spring hastens the process, while days of frost inhibit it.In these days of climate change, trees spread their canopies earlier on average than they used to.They flower sooner, too, and they change color later in the fall.In recent decades southern species do better than before in northern climates: Will pecans enjoy the newly changed winters of Northern Michigan?
One project —budburst—seeks to enlist amateur scientists in charting the leaf-out times for different tree species.If readers wish to join this year’s study, they can sign up this year at budburst.org
All plates taken from; Mauseth, James D. “Plant Anatomy.” Benjamin/Cumming Publishing Company, Inc.: Menlo Park, California, 1988.
In the broadest sense, aquaculture means growing water plants and animals for food, but in the Great Lakes area, it refers mostly to fish farming, raising fish in ponds or within nets in a defined area. The practice is controversial with entrepreneurs claiming it can be done without harming the environment and environmentalists countering that it can threaten important ecosystems. Whether it should be done in Lake Michigan or Lake Huron raises still more questions. In this feature, two of our contributors, Stewart McFerran and Charles Weaver, take up the issue, each supporting opposing sides.
Swimmer’s Itch plagues many Michigan lakes. Children are especially affected as itchy red bumps appear on legs and torso, soon after swimming. Little can be done to alleviate the itching—the old remedy of baking soda is probably as good as any. In a few days it disappears on its own, anyway.
The cause of the itch has been known for many years: a tiny parasite inhabits snails of the lake, shedding them into the water on warm summer days.These cercariae are neither bacteria nor viruses, but a member of the flatworm phylum.In short, they are worms.Many years ago, at the University of Michigan Biological Station, I remember seeing them emerge from snails confined to a watchglass under a low-power microscope.Compared to other such water creatures, they weren’t that small.You could see them with your eyes if you cared to look.
After leaving the snails, apparently tired of the pace of life there, they swim around looking for a secondary host, frequently diving ducks such as the Common Merganser.Finding one, they bore through its skin, somehow finding one another in the circulatory system to mate (I believe the animals are bisexual).Afterwards, they migrate to the digestive tract where they produce eggs ready to be shed into the water with the duck’s feces.Gaining the freedom of open water, they locate snails to infect, thereby completing the cycle.
We humans should be bystanders to this unwholesome series of events, but for one thing: the cercariae mistake us for ducks.Only after entering the outermost layer of skin do they realize their awful mistake, but it is too late for them: our body’s immune system reacts to kill them off, that response leading to an angry, itching bump, swimmer’s itch.
Various methods have been used to control the pest.At least two of them have been tried locally: copper sulfate and removing duck populations.Copper sulfate kills snails, one of the hosts, but that method has been largely abandoned because it is not particularly effective in the long run and because it has harmful effects on other life.
Getting rid of ducks is easier said than done.You can’t shoot them all—after all, there are game laws and many of us (including me) like them.One technique is pyrotechnics.At first I thought this had to do with firecrackers and bombs to drive away flocks, but that is not exactly so.As applied to duck control, pyrotechnics has to do with firing a variety of noisemakers including propane cannons, thunderboom sticks, and bird bangers.A loud noise sends flocks flying, no matter what the source.
Glen Lake has tried this method for several years with inconclusive results.The Glen Lake Association on its website reports the itch still is bothersome, but not as bad as at Higgins Lake, where no such control has been attempted.For some persons, the intermittent detonations may prove as annoying as the itch.
A friend whose family owns a cottage at Glen Lake for many years tells me that the lake has always had a swimmer’s itch problem.The red, itching bumps were a rite of summer.Usually, they do not discourage children to the point they will not go in the water.Swimming and splashing in the water are just too much fun.
There are some things you can do to avoid swimmer’s itch (aside from scaring ducks and poisoning snails).There is some evidence that the cercariae are to be found more often on sunny, warm days, especially close to shore.Onshore winds drive them close to beaches where children are likely to play.Shorter swimming sessions might make infection less likely, too.Unfairly, suntan lotions often contain compounds that attract the itch organisms.Parents cannot catch a break—they must protect their children from the sun and from annoying creatures in the water.Apparently you cannot do both at the same time.
My reaction is that we will probably have to use these common sense measures of control—at least for now.As a duck lover, I hate to see flocks constantly chased off lakes by loud noises.Besides, how long will it take for them to get used to booms and pops?After all, the sounds of traffic in New York City used to be so quiet that they were ignored in 1850.Now, in 2017, it is no different, only we accept 70-decibel noise as normal.Wouldn’t the ducks do the same as we did—learn to ignore the noise?
Richard Fidler is co-editor of Grand Traverse Journal.
Locally-produced digital magazine featuring nature and local history from the Grand Traverse Region.