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R/V Lake Guardian
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Travels the Length of Lake Erie

Lake Guardian made her way back past Mackinac City and turned south. She traveled on Lake Huron past Alpena and on through the St. Clair River towards Lake Erie. Her studies had shown that the dirtiest areas of the Great Lakes were the riverways that lead into the Great Lakes. The St. Clair and Detroit Rivers were two of them, so Lake Guardian stopped to watch them. Nearby she saw the big smokestacks of care makers in Detroit.

As Lake Guardian cruised along, she started talking with a walleyed pike named Wally. Wally thought it was great that Lake Guardian was working so hard to gather information to help keep the Great Lakes clean. He asked Lake Guardian if she was going to talk with the mayflies. Lake Guardian didn't know what a mayfly was. "You have to meet the mayflies," exclaimed Wally, "They're famous! Mayflies are insects that live in the water, and they do not like water pollution at all. If you find mayflies, you know the water must be clean and healthy because mayflies just can't live there unless it is. Their homes must be cool with lots of oxygen." Wally told here how scientists keep track of how many mayflies there are because it helps them know whether the water is clean or not. Many schools and their students volunteer to count mayflies in streams, creeks, and lakes newer their homes to help. When the number of mayflies gets too low, it tells the scientists that there may be a problem with too much pollution in the water. Wally explained, "Mayflies are famous in Lake Erie because they let everyone know that Lake Erie was very sick in the 1960s. Boy, was that a bad time for all of us. I lost a lot of my family back then. Someone noticed that there weren't very many mayflies left, and that was when all the human beings realized that they had to start taking care of Lake Erie if they wanted it to provide them with good water, fish, and everything else." Lake Guardian was glad to hear that people were working to keep Lake Erie clean, but she knew her job was to investigate more.

Lake Guardian decided to continue here journey around Lake Erie on the southern shore, starting with Toledo, Ohio. Toledo was famous for the beautiful, it still was a concern of Lake Guardian's. She stopped to count the mayflies and study how much pollution was being given off by the big glass factories. She continued on to Cleveland, where there are lots of factories making steel and cars. Lake Guardian wanted to look for mayflies here too. Wally explained that industries like the one making steel, cars, and glass get very hot when they melt the glass and steel to make cars and windows. They use the water to cool off the steel and glass, which means that they let off lots of warm water into the lake. This is bad for the mayflies because they need cool water to live, as do many other plants and animals.

Lake Guardian crossed the Lake to look at the beautiful northern shore of Lake Erie and its
farmlands. Lots of sheep and lambs are raised in Canada near Lake Erie, and Lake Guardian wanted to visit them before she made her way to Lake Ontario.

Story Highlights

Mayflies:

Mayflies are excellent indicators of water quality because they are not tolerant of pollution. Monitoring programs in some Great Lakes states use mayflies as one of several indicators of pollution-free water.

Mayflies are aquatic insects with six legs and three body parts typical of insects, as well as two short antennae. Females deposit their eggs into clear running streams
and lakes singly or in strings, depending upon the species.

Nymph hatch from the eggs and remain in shallow water or burrow beneath the mud and gravel, feeding upon
aquatic plants. When ready to leave the water, they swim to the surface and molt, emerging in adult form. At this point, they are called "duns" and are not yet sexually mature. They crawl into nearby vegetation and wait from several hours to a few days for a final shedding of the exoskeleton and emerge as full-fledged adults. On a still sunny day, males wing upward and float down over and over again. Females join the swarm and find a mate and clay eggs in the water, beginning the cycle anew.

Hot Spots: 11

Clinton River, Rouge River, River Raisin, Maumee River, Black River, Cayahoga River, Ashtabula River, Wheatley River, Buffalo River, Detroit River, Niagara River.

Vocabulary

exoskeleton

monitor

factory nymph
hot water emissions oxygen

industry

steel
mayfly walleye pike

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