INTRODUCTION

With over 20% of the world’s freshwater supply residing in them, the North American Great Lakes are the world’s largest freshwater system (TEACH). Including Lake Erie, Michigan, Huron, Superior, and Ontario, the five lakes are an important source of fresh water and are home to many species of wildlife. However, with the belief that water could dilute any substance, the lakes also became a destination of dumping grounds for many different types of pollutants. Ranging from point source pollution such as industrial waste from drainage pipes to non-point source pollution like pesticide and fertilizer runoff from farms, these pollutants and others have had adverse effects on the lakes. Such adverse effects include reducing the water quality, contaminating soils, and damaging the lake ecosystems. This damage produces harmful repercussions on the fish and wildlife stocks, and to the humans surrounding the Great Lakes region as well. To observe this, we will analyze the tissue concentrations in lake trout of four influential pollutants in Lake Huron, to see if there is a correlation to the total biomass of the lake trout.

BACKGROUND

Sources of Pollution in the Great Lakes

Point-source pollution refers to a direct source of pollution, such as a pipe or other vessel. Early industries like pulp and paper companies located in the Great Lakes region believed that anything could be dissolved in water, and thus neutralized. As a result, many wastes (such as mercury) were dumped into the Great Lakes. There have also been observations of fecal matter pollution from sewage, which results in harmful bacteria such as E. coli and enterococci (Liu et al 2006). Both sewage and other organic and inorganic wastes cause the water quality to decline and bacteria growth to increase (Shear 2006).
Figure 1 (Michigan Department of Environmental Quality 1998) gcfigureofpollutants.pngNon-point source pollution is pollution that does not come from specific locations. Many of these pollutants found in the Great Lakes are air-bound and many others are from fertilizer and pesticide runoff. One of the categories of chemical pollutants is organic contaminants, which are discovered by testing the tissue of fish and mussels found in the Great Lakes. Polychlorinate biphenyls (PCBs) have been found in the Great Lakes and are a result of synthetic fertilizers and pesticides (Agency for Toxic Substances and Disease Registry 2001). Chloro-diphenyl-tichloroethane, commonly known as DDT, was found in all mussel tissue testing sites and is the most common chemical pollutant in the Great Lakes. According to the results from the mussel testing, dieldrin is the second most prevalent pollutant in the Great Lakes, behind DDT. Lindane is also a very harmful insecticide which was found in the tissues Great Lake trout and walleye (Robertson 1998). Another detrimental insecticide, toxaphene, breaks down very slowly in water, so it is still found in the lakes today even though it was banned in 1990 (Agency for Toxic Substances and Disease Registry 1997). A list of all the pollutants found in the great lakes can be seen in Figure 1.

Effects of Great Lake Pollution

The majority of the pollutants that contaminate the Great Lakes are harmful to the ecosystem in a variety of ways. Many times, pollutants move up the food chain, affecting not only the organisms that utilize chemical nutrients like phytoplankton, protozoa and crustaceans, but also the animals who feed upon the smaller organisms. Predators higher along on the food chain tend to accumulate more pollutant residues, which can have harmful effects on humans (Hickey et al 2005).This would include not only such animals as rainbow smelt, walleye and mussels, but humans themselves. And as shown in Figure 2 below, fish stocks have been decreasing in recent years, which we suspect is due to the increased abundance of pollutants.
Figure 2: Graphs of fish Prey Population Stocks (Harvey 2006)

figure2.png

Some of the common organic chemicals from pesticides polluting the Great Lakes such as DDT have been known to be toxic and cause major health problems in fish and other fauna. Fertilizers, phosphate detergents and other pollutants that contain important nutrients have caused major algae blooms which lead to nutrient imbalance and lack of oxygen in the water, reducing fish populations and other wildlife (Shear 2006). Levels of PCBs from point source industrial dumping that were higher than the legal limit approved by the FDA were consistently found in fish in the Great Lakes (Hickey et al 2005).

Sewage is another common pollutant of the Great Lakes, and studies have shown that two kinds of bacteria (enterococcus and E. coli), which are indicators of human fecal matter, were present in 20% of the samples taken from Lake Michigan beaches in 2004 (Liu et al 2006). If ingested by humans, these bacteria could cause such illnesses as extreme as typhoid fever (Shear 2006). Infections, gastrointestinal diseases, and parasites are other possible risks from coming into contact with these bacteria as well (Liu et al 2006). As a result of fecal matter pollution that has been plaguing beaches on the Great Lakes, there was a 32% increase in the number of Great Lakes beach closings and advisories in 2003 (Liu et al 2006).

Mercury, a heavy metal that is known for its toxicity in even small amounts, has been known to affect the lakes as well. And even substances that are not chemically toxic are contributing to the problems of the Great Lakes as well. Tiny particles of solids of pollutants suspended in the water may block sunlight from the water and become breeding grounds for bacteria (Liu et al 2006).

HYPOTHESIS

It is obvious that pollution affects the flora and fauna of the Great Lakes in many negative ways. To demonstrate the direct effects of pollution upon the ecosystem, we will focus on one organism from one of the Great Lakes to enable us to see any trends in pollutions effects on fish biomass. We intend to analyze the tissue concentrations in lake trout of four influential pollutants in Lake Huron, and see if there is a correlation to the biomass of the lake trout that can be seen over a period of several years.

METHODS

We researched the effects of pollution through the Mirlyn website, using science-based search databases to find peer-reviewed or high quality sources. To create our charts for our original analysis on the effects of pollution on the biomass of Lake Huron trout, we used measurements found in peer-reviewed articles on the levels of concentrations of pollutants and trout biomass in the lake. Using these numbers, we used Microsoft excel to plot the pollutant concentrations with the biomass levels to observe any correlations between them. We created several graphs to observe any differences that the two most correlated pollutants might have on trout biomass.

RESULTS AND DISCUSSION

Figure 4 below shows the concentrations of four types of pollutants, including PCB, DDT, Dieldrin, and Toxaphene, found in the tissues of trout in Lake Huron. By comparing the biomass of trout (measured in kilograms) in Lake Huron to the concentrations of the pollutants (measured in nanograms per gram), a strong negative correlation can be seen between PCB and biomass, as well as a somewhat smaller correlation between toxaphene and biomass (Figure 5). Looking at the pollutant concentrations graph, PCB has the highest concentration in Lake Huron , followed by toxaphene.

Looking at the main trends of the charts, specifically the chart of Biomass and PCB Concentration, we observed that when PCB concentration had a sharp peak, the biomass of lake trout displayed a sharp loss during the same time period. Also, when PCB concentrations were at the lowest point in our data between the years 1994 to 1996, the biomass of lake trout increased greatly, exhibiting the greatest peak of biomass in our data (Figure 6). The chart of Toxaphene and Biomass also demonstrated this trend to a lesser extent (Figure 7). The concentrations of DDT and of dieldrin did not seem to have a high correlation with lake trout biomass, leading us to believe that either lake trout biomass is not directly affected by the concentrations of DDT and dieldrin, or that the concentrations of DDT and dieldrin were not enough to have an observable effect on lake trout biomass. From these observations of the data, we conclude that toxaphene and PCB have a correlation with the loss of biomass of lake trout in Lake Huron .

However, although we have demonstrated that there appears to be a correlation between certain chemicals concentrations and the biomass of lake trout, we cannot conclude that there is a direct causation between the two. Noticeable fluctuations of biomass and chemical concentrations of PCB and toxaphene that are not in synchronization with each indicate that there is more affecting the fish biomass than chemical concentrations alone. Third variables, such as fishing trends could be an influence as well. For example, it is possible that there is not as much fishing when there are high concentrations of certain chemicals in the water, thus causing the biomass of fish to increase. Another demonstration that our analysis is not perfect is the fact that we were unable to produce an accurate linear regression line that described the trend in biomass of lake trout as a function of PCB or toxaphene. This may be due to third variables and human errors in primary measurements and/or in our calculations. We agree that we would need more data to create an accurate and fitting linear regression equation to describe the relation.
Figure 3 (Hickey 2006)
Year
Biomass (kg) PCB Conc.(ng/g) DDT Conc.(ng/g) Dieldrin Conc.(ng/g) Toxaphene Conc.(ng/g)
1992
90718474 1575 519.8 60.4 1029
1993
81646626.6 2250 551.1 65.3 1319
1994
149685482.1 1215 672 49.5 430
1995
127005863.6 985 521.3 60.8 526
1996
68038855 1006 667.1 44.6 451
1997
81646626 1213 671.7 52.4 918
1998
68038855 1251 703.8 28.2 376
1999
72574779

2000 71667594

2001 70760409

2002 40823313

2003 63502931

Figure 4 pollutantconcentrations.png These are the four pollutant concentrations in lake trout that we focused on, as seen in Lake Huron.

Figure 5 concentrations_and_biomass.png These are the four concentrations of pollutants compared to biomass. It is clear that when the concentration of certain chemicals (like PCB and toxaphene) decrease, biomass increases.

Figure 6 biomass_pcbconc.png As the concentration of PCB increases, biomass decreases and vice versa.

Figure 7 biomass_toxapheneconc.png As the levels of toxaphene concentration increases, the biomass decreases and vice versa.

Other Effects of Harmful Pollutants on Great Lakes Wildlife

DDT, known for causing the thinning of birds’ egg shells, is another example of the direct effect pollution can have on Great Lake wildlife. Used as a pesticide following World War II, the pollutant greatly reduced bird populations throughout the region, including such species as osprey, Forster’s terns, herring gulls, and double-crested cormorants (Michigan Department of Environmental Quality 2000).

Dieldrin, another pesticide, is hazardous not only to Great Lakes wildlife, where it reduces fish and other species populations, but it affects humans as well. The pesticide is known to regularly contaminate fish humans consume, and has been found to cause cancer in humans (Michigan Department of Environmental Quality 2000).

IMPLICATIONS

The effects of PBC and toxaphene on trout biomass in the Great Lakes show the extent to which pollution can have on Great Lakes wildlife. The other examples provided also help to show that not only are the organisms residing within the lake affected by pollution, but those utilizing the lakes vast resources are also equally affected. Pollution contaminates the sediments, affecting everything from the primary producers up to the secondary and tertiary consumers, and even to humans themselves. With regards to the Great Lakes ecosystem, pollution restricts fish and wildlife growth, causes loss of wildlife and organism deformities, and degrades natural communities. Its effects on humans residing in the Great Lake region include restrictions on wildlife consumption, spread of diseases, loss of fish and other wildlife stock, and the closing of beaches and other recreational activities (Michigan Department of Environmental Quality 2000). It also affects other methods of the waters’ usage, as shown in Figure 8.

Figure 8: Graph of Water Usage from Great Lakes (Michigan Department of Environmental Quality 2000)

waterusagefig3.png

SOLUTIONS

The United State government has recognized that pollution does indeed pose a threat to not only plants and animals, but to humans’ welfare as well. As a result, laws have been passed to regulate and control chemicals and other harmful substances that could contaminate the water in the Great Lakes .

In 1972, the US Federal Government enacted the Clean Water Act, the first of its kind to recognize and emphasize the importance of the preservation and restoration of America ’s water quality. Establishing the regulation of discharge of pollutants into the waters of the US and implementing pollution control programs, the Environmental Protection Agency under this act paved the way for further programs (U.S. EPA 2006). One such program, the Great Lakes Water Quality Agreement (GLWQA), was signed in 1972 between the United States and Canada in order “to restore and maintain the chemical, physical, and biological integrity of the waters of the Great Lakes Basin Ecosystems” (Harvey 2006). In 1987, an amendment was made to the agreement which placed more emphasis on the control and elimination of toxic contaminants, as well as on establishing a broad ecosystem approach to solving Great Lakes ecosystem problems (Harvey 2006). Since the GLWQA, Canada and America have established the State of the Lakes Ecosystem Conference, which since 1992 meets every two years to “report on the condition of the Great Lakes Basin ecosystem regarding progress toward the goals and objectives of the Great Lakes Water Quality Agreement” (Harvey 2006). Indicators of the water quality are based on four categories of stresses, including nutrients, persistent toxic containments, land use, and economic activity (Harvey 2006).

In 1998, Governor John Engler proposed the Clean Michigan Initiative to ensure stable, long-term funding for Michigan ’s environmental protection and recreational needs (Michigan Department of Environmental Quality 1999). To examine how these governmental measures have affected the levels of conentration for the main pollutants (PCP and toxaphene) in the Great Lakes, we decided to plot the same concentrations used before along with the concentrations of these same pollutants found in the other Great Lakes (using data from Hickey 2006) (Figure 9 and 10). As these graphs show, the concentrations of both PCB and toxaphene have decreased over the years. We can conclude that these decreases are in part because of the governmental laws and regulations enacted for the purpose of reducing the amount of pollution released into the lakes. However, there is still a significant concentration of pollutants residing within the Great Lakes. Figure 9 chart.png Figure 10 chart3.png Though the government has implemented laws and regulations to help reduce pollution in the Great Lakes, these measures are not solutions to end pollution entirely. More steps can always be taken to help reduce pollutions impacts; these are just several of the laws already in place that do so.

CONCLUSION

With so many different sources of pollutants, ranging from industrial waste, pesticide and fertilizer runoff, and fecal matter, it is not surprising the extent to which these contaminants have affected the wildlife and ecosystem surrounding the Great Lakes . As seen in the biomass of Lake Huron trout, pollution directly influences the wildlife and environment surrounding the lakes. Such influences include promoting the abundance of diseases that occur in both animals and humans, as well as disrupting the natural balance of nutrients. The government has formed alliances with other countries and has established programs such as the Clean Water Act and the Great Lakes Water Quality Agreement to combat the problems of pollution. However, even though these measures did have an impact on the amount of pollutants found in the lakes and in organisms living in the Great Lakes, there are still many pollutants that negatively affect the Great Lakes ecosystem today.

Agency for Toxic Substances and Disease Registry. ToxFAQs for Polychlorinated Biphenyls(PCBs). Feb 2001. http://www.atsdr.cdc.gov/tfacts17.html#bookmark02 (Oct. 23 2006)

Agency for Toxic Substances and Disease Registry. ToxFAQs for Toxaphene. Sept. 1997. http://www.atsdr.cdc.gov/tfacts94.html (Oct. 23 2006)

Hickey, J.P., Batterman, S. A., and Chernyak, S. M. 2006 Trends of Chlorinated Organic Contaminants in Great Lakes Trout and Walleye from 1970 to 1998. Arch. Environ. Contam. Toxicol. 50, 97-110

Liu, Lubo; Phanikumar, Mantha S.; Molloy, Stephanie L.; Whitman, Richard L.; Shivley, Dawn A.; Nevers, Meredith B.; Shwab, David J.; Rose, Joan B. 2006. Modeling the transport and Inactivation of E. coli and Enterococci in the Near-Shore Region of Lake Michigan. Environ. Sci. Technol. 40, 5022-5028

Michigan Department of Environmental Quality. 1999. First Round of Environmental Bonds sold Over Internet for Clean Michigan Initiative. Office of Great Lakes Activity Report, Lansing, MI .

Michigan Department of Environmental Quality. 1998. Great Lakes Trends : Into the New Millennium. Office of the Great Lakes, Lansing, MI .

Robertson, Andrew, and Lauenstein, Gunnar G. 1998. Distribution of Chlorinated Organic Contaminants in Dreissenid Mussels Along the Southern Shores of the Great Lakes . J. Great Lakes Res. 24(3): 608-619

Shear, Harvey . 2006. The Great Lakes , an Ecosystem Rehabilitated, but Still Under Threat. Environmental Monitoring and Assessment 113: 199-225

TEACH. Water Pollution in the Great Lakes

http://www.great-lakes.net/teach/pollution/water/water1.html (Oct. 23, 2006)

U.S. Environmental Protections Agency. Clean Water Act, July 2006. http://www.epa.gov/r5water/cwa.htm (Oct. 23, 2006)

Links of Interest
State of Michigan website for the Department of Environmental Quality in the Great (http://www.michigan.gov/deq/0,1677,7-135-3313_3677---,00.html, 12-07-2006)

Great Lake Information Network provided by the Great Lakes Comission (http://www.great-lakes.net/index.html, 12-07-2006)

The Clean Water Act (http://www.epa.gov/r5water/cwa.htm, 12-07-2006)

Alliance for the Great Lakes (http://www.greatlakes.org/, 12-07-2006)

*Great Lakes Fishery Commission (our favorite) (http://www.glfc.org/, 12-07-2006)

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