SEDIMENT RECORDS OF A NOVEL ECOLOGICAL STATE FOLLOWING ACIDIFICATION AT BEAR POND, ADIRONDACK MOUNTAINS, NY

Diatoms in sediment cores from Bear Pond representing the last two centuries show that the lake acidified during the early to mid-20th century when many other Adirondack lakes also did so, and that members of the diatom community that had declined during maximum acidification are now increasing again. However, the lake is not returning to its pre-acidic condition but is instead entering a new ecological state that may be unique in its history.

Chrysophyte scales have become abundant in the sediments during the last 2 decades, and the summer phytoplankton community has recently been dominated by dinoflagellates. In addition, the once-clear water has become murky and brown, water levels have risen significantly, and residues of toxaphene from a previous "reclamation" effort by fisheries managers are still present in the sediments and may be leaking into the water column.

Ironically, ongoing recovery from acidification has not returned Bear Pond to its pre-impact state, nor has it made the lake more appealing to visitors because the current novel conditions have compromised its formerly exceptional recreational features.