Lake Mille Lacs
Minnesota
Minnesota Department of Natural Resources
Dear Sirs and Madames of the DNR,
My name is Jackie the Walleye, and I am writing to you today as a walleye fish and fellow member of the biosphere to discuss a very serious problem for both our species, walleye and human alike. In this letter I will explain how mercury from a light bulb can make its way through the food chain and into the human body as a toxic substance. You don’t want toxins with your lunch, and neither do the fish in your 10,000 lakes.
As you know, mercury levels in Minnesota game fish are too high. There are many non-point sources of mercury contamination, so I will limit myself in this letter to only one: light bulbs. Don’t look so surprised. I may be a fish, but I keep myself informed.
Compact fluorescent bulbs contain mercury, which is a toxic substance.
Mercury in the Anthrosphere
Compact fluorescent light bulbs are gaining in popularity because they use less energy than traditional light bulbs and last far longer. This is wonderful for the environment, but there is a downside: The bulbs contain mercury, and you humans often do not dispose of them properly.
The result? Mercury from broken bulbs in garbage heaps and landfills enters the ecosystem. From storm drains and water run-off, the mercury makes its way into the water systems as non-point source pollution.
You may ask yourself, does this walleye like to eat mercury? No, I am not an idiot; I am a fish with a zesty appetite which does not include toxic chemicals. However, it is impossible for me to avoid mercury in my diet. I will explain why.
Mercury in the Hydrosphere
The mercury that enters the aquatic ecosystem quickly sticks with bacteria and changes into something called methylmercury. You know how in the olden days thermometers used to take humans’ temperatures contained mercury, but manufacturers stopped making them when they realized that it wasn’t such a great idea to put a glass tube filled with a toxic chemical under your tongue? That was abiotic mercury, and methylmercury is even worse!
Mercury in the Biosphere
Maybe you are thinking that this new mercury-packed bacteria is spread around like you humans spread bacterial strep throat. No again! Instead, the bacteria are absorbed by tiny life forms like plankton. Guess what the plankton has now? Mercury! And guess who wants to have a bite of plankton?
Me? Of course not. Surely you know that a walleye is a big fish with a big belly. I am waiting for something far bigger to fill me up than tiny plankton.
No, from here the mercury enters the food chain. The mercury-packed plankton get eaten by very small animals in the lake. Imagine that a very small invertebrate, something like a native waterflea, eats the plankton.
The Spiny Water Flea. A good meal for a minnow despite all the sharp points.
Then a hungry little minnow comes along and eats the native waterflea. In fact, that little minnow eats a few dozen waterfleas.
Note: I am an open-minded walleye, but even I confess that humans are revolting creatures. You use minnows to eat the dead skin off of your feet in luxury salons, which we walleye find wildly wasteful and unappetizing.
Then a yellow perch finds that minnow while it’s feeding and gulps it down. The perch doesn’t stop there. It gobbles up the better part of a whole school of minnows.
The yellow perch.
Bio-accumulation of Mercury
Do you follow what is happening? Energy isn’t the only thing being transferred in this food chain. You humans and your sloppy garbage habits have introduced mercury into the food chain, and it’s getting passed along from plankton to native waterflea to minnow to yellow perch. And remember, the minnow ate a lot of mercury-packed plankton, so that minnow’s body had a high level of mercury. Don’t forget that the yellow perch at a lot of those minnows, and every single one had high levels of mercury contamination. This is called bio-accumulation: the substance is accumulating, or gathering, as it passes from one food source to another.
Bio-magnfication of Mercury
The minnows ate loads of native waterfleas (and loads of mercury) and the perch ate practically a school of minnows, mercury-packed minnows! Each time that the mercury travels up the food chain, it is found in higher levels because the mercury has been accumulating (bio-accumulating, to be specific) in the food sources. By the time the yellow perch finds food, it’s getting a meal with mercury mixed in densely. The level of mercury increases from plankton to waterflea to minnow to perch. We call this bio-magnfication: the substance is more concentrated as it travels through the food chain.
Guess who is next in the chain! Yes, finally we come to the best part of this story: me, Jackie the Walleye. My favorite food is the yellow perch. I like to lurk around in the dark, turbid waters, waiting for a perch to swim by. I’m not thinking about mercury levels; I’m thinking about lunch.
The yellow perch has even higher levels of mercury since it’s higher on the food chain.
What do I get in addition to a yellow perch as a reward for my predatory skills: a huge helping of mercury, which acts as a neurotoxin, a poison that harms the nervous system. There have been some limited studies that show mercury is related to how much stamina (strength for a long period of time) a fish has for swimming. I have never participated in these studies, but I can give anecdotal evidence that I just don’t feel like swimming across the lake anymore. I get too tired out and I don’t know why, but I suspect it’s all the mercury that I’ve been eating with my yellow perch diet.
Toxic Mercury Enters the Human Body
Maybe you don’t care about a worn-out walleye, but you should – because you are the next step in the food chain. I can hear you clumsy anglers trudging around on the docks and balancing in your boats. I’m no fool. I’m fifteen years old, weigh almost twenty pounds, and measure almost a yard long – and I’ve never looked twice at your hooks.
I’m almost the size of my careless cousin Kenny, and look how he ended up.
Careless Cousin Kenny poses with his smiling human predator.
The humans who ate my cousin Kenny probably weren’t thinking about the mercury that came with their fish. But Kenny had the highest concentration of mercury in the entire lake! At least that’s what my family says. He got so big by eating so much prey – and all of it had high levels of mercury. The levels kept bio-magnifiying right up to Kenny.
However, Kenny turned out not to be at the top of the food chain, as my family predicted. You humans made sure of that. Now that bio-accumulated, bio-magnified mercury has returned to you – some of it from the compact fluorescent bulbs that you threw in the trash!
This is terrible news for humans because there are scientific studies that show high levels of mercury act as a neurotoxin on the human body. Mercury can harm the human nervous system.
If you think walleyes look nasty, imagine how we view humans. Here is your central and peripheral nervous system. That’s what’s walking down the runway on America’s Top Model™. Now imagine this nervous system with toxic mercury!
Pregnant women and small children should limit how much fish they eat or avoid fish completely. This is because the mercury has a stronger effect on small, growing bodies.
Some of Jackie the Walleye’s very own children are still in their eggs. We walleye don’t feel so sentimental about our children. Sometimes we just eat them.
Note: We walleye do not spend so much effort on our young; we just lay 300 or so eggs and when the babies hatch they are on their own. You wouldn’t believe how much free time Jackie the Walleye enjoys. Thousands of kids and no babysitting! And if I feel hungry, I just eat a few of them.
I would like to advise you to stop eating fish completely, but that would make my a hypocrite since I spend most of my time eating fish myself. I am known in the science world as a piscivore, a fish-eater. Humans and walleye are both predators of fish. We can understand each other better than you might think.
Instead of giving up fish in your diet, I ask that you dispose of your compact fluorescent light bulbs properly. In Minnesota, it is already illegal to throw fluorescent bulbs in the trash, but people do it anyway because they don’t know how to take things to one of the hazardous waste disposal centers, where you are supposed to bring your old bulbs.
We need to be creative in addressing this problem for the sake of your human children.
The walleye community would like the Minnesota Department of Natural Resources to team up with recycling businesses across the state to make light bulb recycling easier and more convenient.
We walleyes often wonder why humans don’t have a special recycling container for light bulbs that can be picked up with the paper, plastic, and glass that is already set out for recycling. People are far more likely to take their bulbs to the curb than to a hazardous waste center. Make it easy on the humans, the walleye, and the food chain.
Think outside the box – and the garbage can.
I thank you for your time. And next time you go fishing, maybe think about hooking a Great Northern Pike. We walleye fish could use a break from that monster.
Sincerely,
Lovingly Yours,
Jackie
Jackie the Informed Walleye
Lake Mille Lacs
Minnesota
Capitol Hill Science 8 