Book Summary: The Living Great Lakes by Jerry Dennis

My Personal Summary

This book is about the history and nature of the five Great Lakes in the U.S.

The Great Lakes hold about 20% of all freshwater on the surface of the planet and provide drinking water to over 30 million individuals.

Over the years, the Great Lakes have suffered from chemical and industrial pollution from companies that have dumped waste into their waters but thanks to strict pollution laws and various clean water acts, the lakes have made an astounding recovery in recent years.

The lakes have also suffered from the introduction of non-native species to the region that have no natural predators and have caused an imbalance in the natural ecosystem.

Fortunately, biologists have been able to come up with clever ways of strategically poisoning these non-native species without harming native species and have thus been able to restore the ecosystems of the lakes to their natural balance.

A series of canals built through the state of New York and other New England states have made it possible for ships to navigate from the Atlantic Ocean to the Great Lakes entirely by water, which has made it possible for the shipping industry to provide an economic boost to the cities that reside near the lakes.

Today the Great Lakes support tourism, shipping and clean drinking water for millions of people. Keeping the lakes clean and healthy is of utmost importance.

Book Notes

  • The Great Lakes (GL) are actually massive. “Calling them lakes is like calling the Rockies hills.”
  • HOMES is a useful acronym for remembering the names of the Great Lakes – Huron, Ontario, Michigan, Erie and Superior.
  • Interesting: Michigan has 3,200 miles of coastline. Only Alaska has more.
  • The GL hold 20% of all freshwater on the surface of the planet.
  • Glaciers formed thousands of years ago and carved out huge basins in the Earth. Then, when the glaciers melted the water filled in the basins, creating the Great Lakes as we know them today.
  • Today, the GL are as clean as ever due to (1) stricter pollution laws and (2) zebra mussels – non-native mussels primarily found in the Black Sea and Caspian Sea that likely made their way to the GL by rogue ships and are known for their amazing ability to filter pollutants out of water.
  • The GL are classified as oligotrophic lakes, which are lakes that are clear, cold and don’t have enough nutrients to support many aquatic plants, animals or algae.
  • The Mackinac Bridge, built in 1957, is the 3rd longest suspension bridge in the U.S., spanning nearly 5 miles long, and connects the upper and lower peninsula’s of Michigan.
  • The Straits of Mackinac are about 5 miles wide and merge Lake Michigan and Lake Huron. All of the other Great Lakes are connected by rivers.
  • In terms of surface area, Lake Superior is the largest freshwater lake in the world. The French named it le lac superieur because it was the northern or uppermost of the Great Lakes.
  • Isle Royal is an island located in Lake Superior that is known as one of the least visited National Parks in the U.S.
  • Interesting: Lake Huron is the only Great Lake without a metropolis located on its shores. Lake Superior has Duluth and Marquette. Lake Michigan has Chicago, Milwaukee and Green Bay. Lake Erie has Cleveland and Buffalo. Lake Ontario has Toronto.
  • Between 1870 and 1900, lumberman cut down over 40 million acres of pine trees in northern Michigan, Wisconsin and Minnesota.
  • Interesting: Loggers cut down trees in the winter because snow was needed in order to haul massive logs by ox-drawn sled and they needed heavy runoffs of spring meltwater to raise rivers enough to float the logs downstream.
  • There are over 140 non-native species of fish and plants that exist in the GL today, which cause unexpected consequences in the food chains of the ecosystems in the lakes because most of these non-native species have no predators so they reproduce rapidly and greatly alter the natural order of the habitat.
  • Due to industrial and chemical companies dumping toxic waste into the GL mostly in the 1960’s-1980’s before clean water acts were enacted, there are huge quantities of toxic materials sitting at the bottom of the lakes. When storms occur, sediments at the bottom of the lakes get stirred up and these toxic chemicals naturally make their way into the food chain. For this reason, many environmental agencies warn people to limit their consumption of fish from the Great Lakes because they likely contain carcinogens.
  • The Welland canal was built to allow ships to pass from Lake Erie to Lake Ontario through a lock system to bypass Niagara Falls.
  • The Welland canal is part of the St. Lawrence Seaway, which is a series of canals, locks and channels that allow ships to travel from the Atlantic Ocean to the Great Lakes all the way to Duluth, Minnesota on the western side of Lake Superior. Without this seaway, there would be significant shipping in the interior of North America.
  • One negative side effect of the Welland canal is that it allowed sea lamprey, a type of eel-like fish, to travel from the Atlantic Ocean into the great lakes. They turned out to be predators of nearly all the native species of fish in the GL. In the 1950’s, biologists treated many of the tributaries of the GL with lampricide, a compound that poisoned and killed sea lamprey without harming many other organisms. Sea lamprey still remain a problem today but lampricide has greatly reduced their negative effects.
  • Another fish that had few natural predators was the alewive, which reproduced so rapidly that sometimes droves of them would die and wash up in massive piles, rotting on beaches. To control the alewive population, biologists imported salmon eggs and dumped them in the GL. The salmon feasted on the alewives and salmon populations increased dramatically, attracting fishers from all over the country.
  • The Erie Canal, which first broke ground in 1817 and was completed in 1825, connected the Hudson River to Lake Ontario and Lake Erie.
  • “The Erie Canal made it affordable to transport goods and passengers to the interior of the continent. Before the canal, sending a ton of cargo by horse and wagon from New York to Chicago cost about thirty dollars. That same ton cost a single dollar via the Erie Canal. America would never be the same. The project made New York the Empire State, transformed New York’s harbor into the busiest in North America, and galvanized the nation.”

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