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Message Subject: The Vaults last part.

walleye express

Posted 12/11/2004 1:49 PM (#25084)
Subject: The Vaults last part.

Member

Posts: 2680

Location: Essexville, MI./Saginaw Bay.

Question 1. What is the Welland Canal?

Answer: The Welland Canal connects Lakes Ontario and Erie. The canal was necessary because the Niagara River, the natural connection between the lakes, has impassable falls and rapids (Niagara Falls, to name one). Therefore, the canal forms an important link for the shipping industry in the Great Lakes-St. Lawrence Seaway system.

Welland canal was built (1914-32) to replace a canal opened in 1829, and was modernized and enlarged in 1972. The canal is 27 miles long with a minimum depth of 30 feet, and it contains eight locks, guiding ships up and down the 326 foot difference in elevation between Lake Ontario and Lake Erie.

Unfortunately, without ecological foresight, this canal also let in two aquatic creatures that forever changed the Great Lakes. The lamprey eel and the alewife. The Lamprey almost decimated the natural Great Lakes Lake Trout populations and forever changed how fisheries personnel think. And the alewife also had a detrimental effect, until the late 60's when they became the main diet of the newly planted Salmon species.

Question 2.
Is there really a problem with chemicals getting into the walleye from eating the round goby, who eat zebra mussels?

Answer: To answer your question -- YES! The process you've described is called biomagnification. Some toxic chemicals found in the Great Lakes, such as DDT and PCBs, are stored in the fatty tissue of organisms, and when one organism is consumed by another, these toxins are further concentrated in the bodies of the predator. This is repeated at each step in the food chain. Biomagnification occurs regardless if non-native species are involved or not, and it occurs in every waterbody around the world.

The top predators in a food chain, such as trout or salmon, may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death. Humans must also be careful about eating certain fish, because the concentrated toxins could affect our health as well. Every year, each Great Lakes state publishes a fish consumption advisory, which informs the public of what quantities of various types of fish from different waterbodies are safe to eat. For a listing of fish consumption advisories, go to GLIN's Fish Consumption Advisory page.

Question 3.What is the foam like stuff that washes up on beaches on lakes and bays?

Answewr: While the foam that washes up on shore may look like the foam in your kitchen sink, lake foam is usually a naturally occurring phenomenon and not caused by pollution. Foam is created when the surface tension of water (the attraction of water molecules for each other, which gives a drop of water its round shape) is broken down and air is mixed in, causing bubbles. Surface tension can be reduced by natural organic compounds as well as pollutants, such as soaps and detergents.

Natural organic compounds are released into the water by decomposing algae and fish. As wind stirs the water, air is mixed in with the water because of its reduced surface tension, and foam is produced. Foam will often collect in large quantities on windward shores, and that's why you may see foam on the beach. Natural foam may have a dirty brown color, and will smell earthy or fishy.

Foam from detergents and soaps is now uncommon, although this was not always the case. In the 1950's and 60's, most detergent was non-biodegradable (not able to be broken down by bacteria). This type of detergent made great suds, but caused a lot of water pollution. Fortunately, most detergents made today are biodegradable, so they are unable to produce the long-lasting foam found on shorelines. Foam from detergents will have a perfumey smell.

Question 4. Do the Great Lakes create their own weather systems?

Answer: The Great Lakes themselves do affect the hydrologic cycle. The large surface area of the Great Lakes causes quite a bit of evaporation, which contributes to much of the moisture in the region. This moisture will either stay in the air and create those hot, humid days of summer, or condense and form clouds and, eventually, precipitation. This precipitation (rain, snow, sleet) will either fall back into lakes or will be absorbed by soil and become groundwater*. And some groundwater eventually enters back into the lakes, starting the cycle all over again.

Great Lakes weather is also affected by air masses from other regions. While the prevailing winds in this region are from the west, cold, dry weather from the Arctic region as well as the hot, humid weather from the Gulf of Mexico can also affect the Great Lakes weather system, causing quick and sometimes drastic changes in the weather (have you ever heard the saying, "If you don't like the weather in Michigan, wait five minutes!"). Autumn and spring are especially affected by clashes of warm and cold air that can produce strong winds and storms.

Well, thats it. This little exercise has come to an end.

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