Even though urban, municipal and industrial pollution as a threat did not meet the criteria as a statewide priority threat, resolution of this threat will require statewide, national and international efforts, as well as restoration efforts at specific contaminated sites. The severity of this threat is considered to be greater in the Lower Peninsula and Lake Erie and Huron basins than in the Upper Peninsula and Lake Michigan and Superior basins. See Appendix E for a graphic representation of the relative severity of threats between regions.

Effects of this threat on wildlife are expressed in many ways, including reduced reproductive rates of Bald Eagles along the Great Lakes coast; reduced rates or complete lack of reproduction in mammals near contaminated sites; threats to federally endangered species from contaminated areas; loss of freshwater mussel beds; and health advisories regarding consumption of fish. The most serious effects may still be unknown. The exact effects (direct or indirect) of many chemical pollutants on wildlife species are poorly understood; in many cases, knowledge is limited to the effects on game species alone. Through the years, pollution has been identified as one of most influential factors causing population declines and losses of species in the Great Lakes region. Environmental laws have helped reduce some contaminants, but the effects of pollution persist. Contaminants such as road salts, mercury, acid precipitation and increased sewage pose real questions and threats for the future of Michigan wildlife. See the Ecological Overview for more information about sources of aquatic contaminants and changes measured over time.

Five classes of contaminants may affect landscape features and wildlife (Gard et al. 1992). Three of these classes have their primary effect at the species level. Two, herbicides and acidic precipitation, may have effects at both the landscape feature level and directly on species.

Herbicides
These contaminants contain a number of compounds that have a variety of effects on vegetation, from defoliation to atrophy of plant roots. When used improperly, they can cause prolonged effects to vegetation used by wildlife species. Herbicides are also a valuable tool for conservation, including control of invasive plants. However, indiscriminant spraying of herbicides can kill rare or endangered plants. It can also kill plants with which many insects, including numerous SGCN, have obligate relationships, potentially eliminating entire colonies of rare insects (e.g., Cuthrell 2000, Rabe 2001).

Some concerns have arisen concerning use of certain herbicides and potential links to amphibian population declines (Hayes et al. 2002, Kiesecker 2002). Although Kiesecker et al. (2004) found that the direct cause of wood frog malformations in sampled ponds in Pennsylvania was a nematode parasite, they also found that frogs living in ponds with agricultural run-off developed abnormalities significantly more often than those in ponds without run-off. Amphibians tend to be more sensitive to environmental changes, but herbicides could also have long-term effects on other wildlife species. The nature of these potential effects are not yet understood.

Organochlorine Pesticides and Related Industrial Contaminants
This group of compounds includes chlorinated hydrocarbon insecticides (DDT, dieldrin, aldrin and mirex) and related industrial materials (PCBs, dioxins and furans). These compounds are persistent and fat soluble, characteristics that make bioaccumulation in animal tissue easier. Bioaccumulation of PCBs, DDT and metabolites in fish depends on factors such as growth rate, lipid content, and size, as well as environmental factors, including prey species, food chain length, and limnological factors.

DDT, PCBs and dieldrin have been documented as threats to Bald Eagle populations (Eisenreich 2002), through direct mortality (Elliott et al. 1996) and decreased productivity (Best et al. 1994). DDT, PCBs and metabolites were responsible for declines of Bald Eagles, Ospreys and Peregrine Falcons in Michigan. Although bans or restrictions on use of these compounds have significantly reduced sources, leaching and re-suspension allow continued mobilization in the water column of contaminants captured in sediment. Residual DDT also remains in upper soil layers and accumulates in many terrestrial animal species (DNR 2005b).

The Tittabawassee River demonstrates the long-term threat posed by contaminants trapped in sediments. The Tittabawassee River Aquatic Ecological Risk Assessment Report (MDEQ 2005) concluded the following: levels of dioxin and furan in ecological habitats downstream of Midland are high enough to potentially cause toxic effects to wildlife species; local carp, catfish, shad and bass have levels high enough to potentially cause serious reproductive impairment in fish-eating birds and mammals; similar risks exist in the Saginaw River and Saginaw Bay (MDEQ 2003b), which have important stopover areas for migrating birds.

Another example of an industrial contaminant is Trichloroethylene (TCE), an industrial cleaning solvent. Recent tests in southwestern Michigan have shown groundwater contamination with TCE leaching from a nearby industrial site. The related plume of TCE is expanding toward a federally listed Mitchell's satyr butterfly site. The potential effects of contamination on the satyrs themselves are currently unknown, but areas of extreme contamination upstream of one satyr population were found to be devoid of aquatic life (Hyde et al. 2003).

Organophosphorous and Carbamate Insecticides
Compounds in this group are acutely toxic and have been responsible for a number of wildlife die-offs (Grue et al. 1983); they work by blocking neurotransmitters. Poisonings of wildlife usually occur following exposure to recently treated areas. Although bioaccumulation is not a concern with these compounds, chronic exposure may be a threat. Diazinon intoxication in Canada Geese, Mallard Ducks and Wild Turkeys is the most common organophosphate poisoning seen in Michigan, but Parathion poisoning in Ring-billed Gulls and Sevin poisoning in bees have occurred as use of these compounds in agriculture has increased (DNR 2005b). There is some concern that declines in Black Ducks may be linked to use of insecticide treatments for spruce bud worm (Rusch et al. 1989). Although die-off incidents in the United States are sporadic and infrequent, unregulated use of these compounds in wintering areas of migratory birds remains a concern.

Metals
Due to their stability, metals persist for long periods and cycle slowly in the environment. Many metals have the ability to bioaccumulate through food chains, which is of special concern in aquatic systems. The metals of greatest concern include lead, mercury and selenium. High levels of mercury found concentrated in muscle tissues have been linked to reduced reproductive success in some wildlife species. Mercury has been reported to cause abnormal egg-laying behavior, impaired reproduction, slowed duckling growth, and altered duckling behavior in Mallard Ducks (DNR 2005b). Bioaccumulation poses threats to top predators, including Common Loons, Cormorants, Eagles, Ospreys, snapping turtles and mink (USEPA 2005b).

Direct ingestion of metal sources can also be a direct threat to wildlife. Lead poisoning has been recognized as a mortality factor in waterfowl since the late 1800s. Of 187 necropsies of Common Loons completed by the DNR since 1987, lead was found to be a causative mortality factor in 42 cases; the source was commonly spent lead shot and fishing tackle ingested during feeding activities. Ducks, geese, swans and loons are the most commonly affected wildlife; however, upland game birds, including Mourning Doves, Wild Turkeys, Ring-necked Pheasants and Northern Bobwhite Quail, are occasionally affected. Lead poisoning has also been noted in small mammals and raptors, presumably from the ingestion of lead-contaminated prey (DNR 2005b). The switch from lead to non-toxic shot has significantly reduced the number of birds dying from lead poisoning in Michigan and the U.S.; however, the mortality directly due to lead ingestion may be secondary to the losses due to non-lethal effects of lead, such as reproductive problems, increased susceptibility to disease and infection, and increased predation due to anemia and weakened muscles (DNR 2005b).

Acidic Precipitation
Effects of acid precipitation occur primarily at the landscape feature level, especially in forest and inland lake landscape features. Acidic deposition affects terrestrial landscape features by altering soil chemistry and nutrient cycling. Although chemical changes have not been measured in Michigan's soils, such changes have been documented in forested systems to the south of the Great Lakes. On a regional basis, acid deposition is the second most important air pollutant affecting forested systems, behind only ozone (MDEQ 1999). Secondary effects may include reduced prey availability (Blancher 1991) and increased bioavailability of toxic metals, including mercury. Michigan acts as both a source and receptor for acid deposition (MDEQ 1999).

Other Contaminants
In addition to the contaminants listed above, other contaminants can affect wildlife and habitat. Road salts can affect vegetation and small vegetative communities. A small pocket of unique wetlands in southeastern Michigan that contains a relict forested bog is in jeopardy due to increased salinity from road runoff (MNFI 2005). It is not yet clear how road salts may affect other vegetative communities required by wildlife.

Any broad application of insecticides has the potential to effect non-target species. This is of particular concern when insecticides are applied in natural environments, as done with gypsy moth spraying. This activity has the potential to affect many non-target Lepidoptera species (Peacock et al. 1998), including numerous SGCN. Spraying for mosquitoes to control West Nile Virus may also affect many other wetland-dependent insect species, including numerous SGCN. Reductions in insect abundance due to large-scale spraying of insecticides may also affect other insectivorous species, such as bats and birds (USFWS 1999).

Conservation Needs to Address Urban, Municipal and Industrial Pollution Issues:

Land, Water & Species Management

• Develop action plans to prevent environmental contamination from identified sites and sources
  
  
• Implement best management practices that prevent secondary effects from regulated use of pesticides
  
  
• Form partnerships with conservation organizations to assist with contaminant issues in wintering areas of migratory birds
  
  
• Promote use of water retention sites for filtration of pollutants prior to entering local water bodies

Law and Policy

• Ensure existing environmental laws are properly enforced
  
  
• Recover costs of restoration from liable parties or compel them to perform the restoration work
  
  
• Collect penalties for natural resources damages, which can be used to fund restoration

Education & Awareness

• Implement programs to encourage anglers to voluntarily replace lead fishing tackle with less toxic alternatives
  
  
• Promote agricultural practices that reduce contaminants and run-off
  
  
• Promote practices that reduce private non-agricultural use of pesticides
  
  
• Encourage establishment of and participation in household hazardous waste collection

Research, Surveys & Monitoring

• Continue research on primary and potential secondary effects of contaminants on species
  
  
• Identify, quantify and monitor sites, sources and composition of significant contamination
  
  
• Conduct research to determine whether the effects of pollution vary by both physical and chemical characteristics of the pollution and the species of wildlife encountering it
  
  
• Conduct research to assess effects of both municipal sewage and residential septic systems
  
  
• Develop and test best management practices to prevent secondary effects from regulated use of pesticides