Recent Evidence of Biological Recovery from Acidification in the Adirondacks (NY, USA):
A New Regional Paleolimnological Perspective

Kristina M. A. Arseneau1, Charles T. Driscoll2, Lindsay M. Brager1, 3 and Brian F. Cumming1

The Adirondack region of New York (USA) has been significantly impacted by acid deposition. Since the implementation of the Clean Air Act Amendments, the area has shown improvements in water chemistry. However, little work has been done to assess biological recovery in the region. Assessing biological recovery is often difficult due to a lack of long-term monitoring data but paleolimnology can overcome this problem. Paleolimnology uses the physical and biological characteristics of lake sediments to infer lake histories. Biological proxies such as diatoms, chrysophytes, and cladocera can be correlated to environmental variables like pH and temperature. By quantifying changes in these proxies overtime, paleolimnologists can assess changes in the aquatic environment. The goal of this investigation was to identify if biological recovery has followed chemical recovery in three acid-impacted Adirondack lakes using paleolimnological techniques. Additionally, a lake which did not acidify was included in the study to serve a reference system. Changes in the lakes? chrysophyte and cladoceran fossil assemblages were analyzed from ca. 1760-present in 210Pb dated sediment cores. Multivariate statistics were applied to compare changes in fossil species composition with measured changes in chemical and climatic variables. Recent (post-ca. 1995) declines in chrysophyte species with low pH optima suggest that biological recovery from acidification is occurring in the study lakes. However, recent (post-ca. 1970) increases in colonial chrysophyte taxa suggest that the species assemblages are not returning to their predisturbance state, likely due to an influence of climate warming. The cladocera remain unresponsive to increasing pH and several local/regional factors may be preventing their recovery (i.e. predation, calcium depletion, climate warming, etc.). This study provides evidence that biological recovery is underway in the Adirondacks but that recovered assemblages are unlikely to return to their pre-industrial state due to other environmental factors.

1 Paleoecological Environmental Assessment and Research Laboratory (PEARL), Dept. of Biology, Queen's University, 116 Barrie St., Kingston, Ontario, Canada K7L 3N6 (email: ; tel: 613-533-6000 ext: 75161)
2 Center for Environmental Systems Engineering, Syracuse University, 151 Link Hall, Syracuse, New York, United States 13244
3 Dept. of Oceanography, Dalhousie University, Life Sciences Centre, 1355 Oxford Street, Halifax, Nova Scotia, Canada B3H 4J1