to inhibit growth of phytoplankton populations (Fisher et al. 1973) and 

 interfere with protozoan chemotaxis (response to chemical stimuli; Walsh and 

 Mitchell 1974). They can stimulate and inhibit bacterial growth (Bourquin and 

 Cassidy 1975; and Keil et al. 1972). No evidence exists that bacteria in 

 their natural environment can metabolize and break down PCBs (Sayler et al. 

 1978). 



PCBs can concentrate in the tissues of certain species directly from the 

 environment as readily as it bioaccumulates via food. Benthic invertebrates 

 and zooplankton bioconcentrate PCBs. PCBs pose a potential health hazard to 

 people because they accumulate in sediment where bioconcentration by 

 commercially important benthic species such as lobsters, soft-shelled clams, 

 and blue mussels, occurs (Edwards 1977). 



A preliminary inventory in coastal Maine in the mid-1970s failed to show PCB 

 contamination in estuarine and marine sediments or in certain estuarine and 

 marine organisms (personal communication from J. Hurst, Maine Department of 

 Marine Resources, W. Boothbay Harbor, ME; April, 1979). More recently, PCBs 

 were detected in blue mussels from four locations along the Maine coast 

 (Council on Environmental Quality 1979). The levels measured at each site 

 were: 15 ppb at Blue Hill Falls (region 4); 80 ppb at Sears Island (region 

 4); 55 ppb at Cape Newagen (region 2); 60 ppb at Bailey Island (region 1); and 

 95 ppb at Portland (region 1). Also, PCBs have been found in eggshells 

 of bald eagles in Maine (see chapter 16, "Terrestrial Birds"). 



Studies in Scotland have shown that PCBs may accumulate in small amounts in 

 macroalgae growing in areas exposed to PCB pollution (Parker and Wilson 1975). 

 These may be transferred to grazers, such as limpets and sea urchins, which in 

 turn are prey for certain waterbirds (i.e., purple sandpipers, herring gulls, 

 and common eiders) . Bioaccumulation of PCBs in birds interferes with 

 reproduction. The effects of PCBs on seabirds, wading birds, bald eagles, and 

 marine mammals are discussed in chapter 14, "Waterbirds," chapter 

 l6,"Terrestrial Birds," and chapter 13, "Marine Mammals." 



The resuspension and redistribution of PCBs by dredging can increase PCB 

 concentrations to critical levels (Maurer et al. 1974; see "Dredging" under 

 "Ports and Navigation" above) . 



Air Pollution 



Substances that pollute the air are released by factories, power plants, and 

 motor vehicles. Polluted air is also transported to Maine from other parts of 

 the country by winds. Control of air pollution in Maine includes cleansing 

 the local point sources and relying on other areas of the country to keep 

 their air pollution levels low. 



Air pollution is greatest in and around large cities, where the automobile is 

 the chief polluter. In small towns, air pollution is derived mostly from 

 industrial point sources and from stationary fuel-combustion. In rural areas, 

 most of the air pollution is transported from more populated areas or arises 

 from large individual point sources. 



Although the air quality in coastal Maine is generally good, areas exist that 

 do not meet the criteria set forth by the EPA in the National Ambient Air 



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