Lecture 26: Lake Erie - Inland Sea in Our Backyard

1. Lake Erie - Inland Sea in Our Backyard
- Geologic History
- Aquatic Nuisance Species and Pollution
- Looking to the Future
Reading:
a) Lake Erie Facts
b) Zebra Mussels in North America - The Invasion and its Implications
Graphic: True-color image of the Great Lakes, provided by the SeaWiFS Project, NASA/GSFC and Orbimage.

2. The Great Lakes are Great!
- Shoreline comparable to shoreline of continental US
- Contain about 1/5 of the world's fresh water supply
- Many biological, chemical and physical processes that occur in the ocean also occur in the Great Lakes
Graphic: Great Lakes shoreline compared with East Coast shoreline, courtesy of Great Lakes Environmental Research Lab, NOAA.

3. Lake Erie Facts
Physical:
4th largest Great Lake (12th largest in world)
210 miles long, 57 miles wide
570 ft above sea level
856 miles of shoreline
Average depth 62 feet (maximum depth=210 feet)

Processes:
Flushing time = less than three years
Erie exposed to greatest impacts of urbanization and agriculture
Warmest and most biologically productive of the Great Lakes
Often the only Great Lake to completely freeze over in winter

4. Lake Erie Bathymetry
Western basin - shallowest, most biologically productive
Central basin - largest, has a seasonal "dead zone" (low O2)
Eastern basin - deepest basin
Graphic: Courtesy of National Geophysical Data Center, NOAA.

5. Formation of the Great Lakes
Geologically young -formed as glaciers retreated ~15000 yrs ago
The lakes are still changing today - Niagara Falls has moved 7 miles upstream in the last 12,000 years
Graphic: The Great Lakes: An Environmental Atlas and Resource Guide, courtesy of US EPA and Environment Canda.

6. Land Use and Fisheries
Graphic: Great Lakes: An Environmental Atlas and Resource Guide, courtesy of US EPA and Environment Canada.

7. Environmental Concerns
Shoreline erosion
Pollution
- "nutrient pollution"
- pathogens
- toxins
- harmful algal blooms
Loss of habitat and biodiversity
"Exotic" Species
Graphic: The Great Lakes: An Environmental Atlas and Resource Guide, courtesy of US EPA and Environment Canada.

8. What is an Exotic Species?
Non-native species (often with no natural predators)
Can disrupt ecosystems
Some are economically damaging
- infrastructure
- water quality
- fisheries
- tourism/recreation
Graphic: (top) Spiny water flea, photo courtesy of US Fish and Wildlife Service, (bottom) Zebra mussels, S.Van Mechelen, photographer, courtesy of Univ. of Amsterdam, courtesy of Great Lake Environmental Research Lab, NOAA.

9. Exotic or Native?

10. Zebra Mussels - Ecology Out of Balance
- Entered Great Lakes via ballast water
- Adult females can produce 40,000 eggs per year
- Spreads quickly, attaches to most surfaces, outcompetes native species
- Millions of $$$ spent for cleanup and control
Graphic: (top) Balllast water dumping, photo courtesy of Ohio Sea Grant, (center) Zebra mussel, photo courtesy of GLSGN Exotic species library, Ohio Sea Grant, (bottom) Zebra mussels clogging outboard engine, S.Krynock, photographer, courtesy of National Sea Grant Network Exotic Species Graphics Library.

11. Zebra Mussels - An Aquatic Invader
Zebra mussels are now found in all of the Great Lakes and much of the Mississippi River drainage system.
Graphic: Zebra mussel distribution in 1990 and 2000. Courtesy of USGS.

12. Impacts on Fisheries
Zebra mussels influence physical properties of their environment
By filter feeding they increase water clarity and remove food for large fish
Zebra mussels have had a negative impact on Lake Erie fisheries
Graphics: (top) Zebra mussels on fine-grained sediments in Western Lake Erie, photo ourtesy of USGS, (bottom) Walleye, an economically important native species, photo courtesy Wisc. Sea Grant, see http://seagrant.wisc.edu/greatlakesfish/walleye.html

13. A Tangled Net - Aquatic Nuisance Species (ANS) and Synthetic Organic Chemical Pollution
Lake Erie PCBs were thought to be locked in the sediments and out of the food chain - two ANS changed this...
PCBs in the tissues of:
Smallmouth bass - 1100-1800 ppb
Round gobies - 200-800 ppb
Zebra mussels - 100 ppb
2000 ppb - level at which Ohio Dept. of Health issues a "no human consumption" advisory
Graphic: Courtesy of Ohio Sea Grant and Ohio State Univ.

14. The Latest Wrinkle – Aquatic Nuisance Species (ANS) and Nutrient Pollution
Zebra mussels change phosphorus cycling in the lake by excreting large quantities of phosphorus
Phosphorus is now increasing, accompanied by blooms of harmful algae, particularly microcystis, which are rejected as food by zebra mussels
Microcystis is toxic to fish and impairs water quality for humans
Graphic:Microcystis blooms on Lake Erie (top) courtesy of Landsat, (bottom) courtesy of NOAA.

15. Controlling ANS
Regulation
- ballast water exchange
Public education
Aggressive tactics
- poisons
- introduce non-native predators
Research
- better understanding of the ecology of the nuisance species
Graphics: Purple loosestrife, Lake Huron, K.Holland, photographer, courtesy of US EPA, (bottom) Zebra mussels washed up on a Lake Erie beach, Bay City Times, Courtesy Great Lake Environmental Research Lab, NOAA.

16. "Cleveland's Municipal Stadium Attracts New Fans" -Ohio Sea Grant Twine Line Oct/Nov 1997
In 1997, most of the Brown's Municipal Stadium was used to build 3 artificial reefs off Cleveland's shore
- An economically and ecologically sensible use of clean fill
- Support 20-60 times more fish than adjacent areas of the lake
- Each year, reefs generate tourism dollars equal to 2.75 times their cost*
* Ohio Sea Grant evaluation.
Graphics: (top) Hauling debris from Municipal Stadium, (bottom) Construction of Stadium Reef, D.Kelch, photographer. Both courtesy of Ohio Sea Grant.

17. Preview of Next Class
Review for Final Exam
Final Exam: Tuesday May 8th, 12:45 - 3:00 pm, Bowman 133
Graphic: A worm, lumbriculidae and an amphipod, Diporeria, swimming at the sediment surface, courtesy of NOAA Great Lakes Environmental Research Lab.