EARTH 112 - Great Lakes

Environmental policies aimed at protecting water from pollution

Farm runoff like pollution of Lake Erie is largely unregulated by federal law. Up until the 1970s, there were no US federal laws regulating pollution of natural waters.

High probability effects of climate change on the Great Lakes

Flooding More nutrient runoff, blooms, and dead zones Extreme fluctuations in Lake water levels Increased water temperature Decrease in Lake water turnover (mixing)

Where banded iron formations (BIFs) come from

From iron-rich oceans, in which iron reacts with oxygen to form iron minerals that were deposited to the seafloor.

Formation of the Great Lakes

Giant glaciers eroded Earth's surface, carving out the basins that now hold the Great Lakes. The weight of the glaciers pushed down the Earth's crust, forming the basin that now hold the Great Lakes.

Effect of climate change on harmful algal blooms in the Great Lakes

Higher temperatures favor bloom-forming algae. Climate change is causing bigger storms, which leads to more runoff, which causes bigger harmful algal blooms.

What Lake is shown here?

Huron

Predicted effects of climate change on Great Lakes ecosystems

Invasion by non-native species Replacement Emergence Extinction

St. Lawrence Seaway

It allowed ships to travel from the Atlantic Ocean to the Great Lakes. It never fully achieved the expected economic stimulus, in part because of limitations on the size of ships that could pass through it. It allowed invasion of non-native species, which would devastate Great Lakes ecosystems.

Sea lamprey able to devastation of Great Lakes fish populations

Sea lamprey, previously blocked by barriers such as Niagara Falls, were able to enter the Great Lakes through shipping channels. Great Lakes populations such as Lake Trout were slow-growing, could not bounce back quickly. There were no natural predators of sea lamprey in the Great Lakes. Lake trout and other Great Lakes species did not have natural defenses against the sea lamprey.

Alewife take-over and massive die-offs in Lake Michigan

Shipping channels allowed alewife to migrate from the Atlantic to the Great Lakes; with no top-down control from lake trout the alewife took over, but alewife struggled with some Great Lakes conditions, leading to die-offs.

What Lake is shown here?

Superior

Imagine you turn on your tap in Ann Arbor, MI, fill your glass with water, gulp it down, and later use the restroom and flush this water down the toilet. True or False: This water will eventually find its way to the Great Lakes.

TRUE

Which coast in the in the US is the longest?

The Great Lakes Coast

Original structure and flow of the Great Lakes

The Great Lakes have always been connected, but you couldn't sail from the ocean to Lake Superior until we built canals.

Age of the Great Lakes

The Great Lakes were formed when glaciers melted about 14,000 years ago.

Harmful algal blooms

Produce toxins that can be harmful to people and animals. Threaten drinking water, fishing, and other recreation. Often form dense scums. Can occur in rivers, lakes, reservoirs, and oceans.

Water in the Great Lakes source

Rain and Snow

Factors contributing to GL water budget

Rain and snow (precipitation) over the lake Evaporation Runoff

Changes in land use in the Great Black Swamp area, and their effects in the late 1800s and early 1900s

Removal of wetlands and vegetation reduced the capacity of nature to filter out nutrients, leading to harmful cyanobacterial blooms.

Causes of harmful algal blooms in Lake Erie in the past 20 years

Runoff of fertilizers and nutrients from farm fields. Invasive mussels, which filter out "good" algae.

Effect of invasive mussels on the Great Lakes food web

The mussels are filter feeders that consumed many of the primary producers. Because there aren't native fish that efficiently eat the invasive mussels, the mussel invasion resulted in greatly reduced energy going towards fish. It was a bottom-up effect.

Introduction of salmon into the Great Lakes

The salmon were brought in from the Pacific coast. The introduction of salmon into the Great Lakes created a word-class sport fishery. As a tertiary consumer, the salmon effectively controlled alewife. Salmon were raised artificially in a "hatchery".

Sedimentary rock layers in the Michigan Basin

Their erosion, first by rivers and then by glaciers, created the Great Lakes basins They were formed by seas that covered this area hundreds of millions of years ago They include fossils such as corals and shark teeth They are thick; up to 15,000 feet in total

How geological processes provided us with natural resources for economic activity

ancient iron-rich oceans deposited banded iron formations, from which we now get iron for steel evaporation of ancient seas gave us salt deposits, which we mine for use in melting ice on roads in the winter hot waters circulating through fractures in the midcontinent rift formed ore deposits, which provide us with copper for wiring, etc.

A raindrop falls in Lake Superior. About how long will it take to reach the Atlantic Ocean?

hundreds of years

Evidence of midcontinent rift

igneous rocks around Lake Superior copper ore deposits

Order of events through geological history that led to formation of the Great Lakes

iron-rich oceans > midcontinent rift > inland seas > river valleys > glaciers

Why Lake Superior is deeper than the other Great Lakes

A midcontinent rift formed a valley, which then filled with sediments and sedimentary rock layers. Glaciers then eroded the sediments and rocks to create the basin that now hosts Lake Superior.

The role of nutrients in harmful algal blooms

Algae/cyanobacteria need the following nutrients to grow: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (CHNOPS). Phosphorous and nitrogen are often limiting nutrients in aquatic ecosystems (e.g., oceans and lakes). Phosphorus from agriculture (fertilizer and manure washed off farm fields) is important in "feeding" the blooms.

Farming best management practices (BMPs) and their implementation in our three case studies

Best management practices ("alternative methods") have been scientifically shown to reduce nutrient runoff compared to conventional methods. BMPs include restoring some aspects of the Great Black Swamp, including wetlands and vegetation at the edge of fields and streams. The nutrient pollution problem is a cost of industrial farming and cheap food.

Evidence of the glaciers that carved the Great Lakes, and the ancestral lakes that preceded them

Cliffs on Mackinac Island were made by waves from ancient Lake Algonquin. Erratics all over the midwest are evidence of the activity of massive glaciers. Moraines are ridges that were left behind by debris from melting glaciers.

Link between polar vortex, climate change, and Great Lakes Water levels

Climate change has been linked to a destabilized jet stream, which can lead to polar vortex. Polar vortexes resulted in very high winter ice cover, which led to reduced rates of evaporation. Ice cover reduces evaporation in part by reflecting sunlight and reducing warming of lake water during the winter.

Costs of high great lakes water levels

Damage to roads Damage to businesses like shanties in Leland ("Fishtown") Erosion of bluffs and damage/destruction of houses on Lake Michigan "armoring" the lakeshore with seawalls, etc. Moving houses away from the shoreline

Conditions that were primarily responsible for record low water levels in the Great Lakes in 2013

Decreased winter ice cover, which increased temperature and evaporation.

On the diagram, which of the labeled rock layers is likely relatively strong?

E

What Lake is shown here?

Erie

TRUE OR FALSE: if you could drain Lake Michigan, you would have been able to walk across the middle of it (from Michigan to Wisconsin) on a bed of mussels during the heydays of BOTH zebra mussels (2000) AND quagga mussels (2010).

False

How the Great Lakes Compact protects water from withdrawal and consumption

It bans large-scale use of Great Lakes water by people outside of the Great Lakes watershed/basin.

Where does Great Lakes water go?

It flows out of the St. Lawrence River to the Atlantic Ocean.

Issues of Environmental Justice

Major sources of pollution, hazardous waste, toxins tend to be located near poor, minority communities. Thus minority populations tend to face more exposure to environmental health hazards. Environmental action that prevents environmental hazards in one location often results in the movement/placement of the hazard to a location where the community does not have the means to fight it. By 1990, environmental organizations recognized that they had not sufficiently addressed environmental justice and many now have environmental justice initiatives.

What Lake is shown here?

Ontario

Processes governing the midcontinent rift, ore deposits, and mining

Ore deposits formed due to circulation of hot fluids through fractures in the Earth's crust at the midcontinent rift. Ore deposits contain metals such as copper. We all use products that were made from copper that comes from mining of ore deposits.

Invasive mussels getting to the Great Lakes

They "hitched rides" in the ballast water of ships that traveled between Europe and the Great Lakes.

Glaciers that that carved the Great Lakes

They were a part of the Laurentide Ice Sheet, which covered 5 million square miles. They moved. They were 1-3 miles thick! They left behind moraines. When they melted, they formed proglacial lakes.