| Patuxent Science Meeting 2006 Poster Abstract |
| | Restoration of the Lake Michigan ecosystem: a 33-year study of |
| | declines in pollutants in Red-breasted Merganser eggs |
| | Heinz GH, Stromborg KL (FWS), Faber R (St. Mary's College, MN) |
| | The Great Lakes have suffered a long history of contamination by organochlorine pollutants. |
| | These pollutants resulted in devastating declines in populations of fish-eating birds. Regulations |
| | banning or strictly regulating certain pesticides and polychlorinated biphenyls (PCBs) began in |
| | the early 1970s, but some of these contaminants were so persistent that it took decades before |
| | bird numbers rebounded. As a means of documenting the gradual declines in these pollutants |
| | that corresponded to the recoveries of fish-eating bird populations, we measured organochlorine |
| | pollutant concentrations in eggs from red-breasted mergansers (Mergus serrator) in |
| | northwestern Lake Michigan. We collected eggs three times, spaced 12 years apart (1977-78, |
| | 1990, and 2002). From 1977-78 to 1990, concentrations of most organochlorine contaminants |
| | declined in the eggs of red-breasted mergansers, and further declines took place between 1990 |
| | and 2002. Between 1977-78 and 1990 total PCBs decreased 60% (from 21 ppm to 8.5 ppm, |
| | wet-weight). An additional decline of 46% took place between 1990 and 2002 (8.5 ppm to 4.6 |
| | ppm). The total decline between 1977-78 and 2002 was 78%. Between 1977-78 and 1990 DDE |
| | decreased 66% (from 6.5 to 2.2 ppm), and from 1990 to 2002 an additional decline of 36% took |
| | place (from 2.2 to 1.4 ppm) yielding a total decline of 78%. Between 1977-78 and 1990 dieldrin |
| | decreased only 16% (from 0.82 to 0.69 ppm); however, from 1990 to 2002 a 96% decrease |
| | occurred (from 0.69 to 0.03 ppm) for a total decline of 96%. When the earliest data available |
| | (Faber and Hickey 1973) were used as a baseline, the decline in total PCBs was 95% (84 to |
| | 4.6 ppm) and in DDE, 97% (44 to 1.4 ppm). The results of this earlier study, when combined |
| | with those from our three egg collections, show an encouraging decline in organochlorine |
| | contamination in Lake Michigan over the 33-year time frame, 1969 to 2002. Although other |
| | problems unrelated to environmental contaminants still plague the Great Lakes, restoration of |
| | many fish-eating bird populations can be traced to regulations controlling the release of |
| | Friday, September 22, 2006 |