Recent evidence of biological recovery from acidification in the Adirondacks (New York, USA): a multiproxy paleolimnological investigation of Big Moose Lake

Abstract

This investigation provides evidence of biological recovery from acidification in an acid-impacted Adirondack (New York, USA) lake. Water chemistry measurements collected monthly since 1982 show that Big Moose Lake is undergoing chemical recovery from acid deposition. To assess possible biological recovery, changes in chrysophyte, diatom, and cladoceran assemblages are analyzed in a sediment core. Three questions are addressed: (i) is there a significant shift in species composition after the 1995 implementation of the US Acid Rain Program? (ii) Are post-1995 changes in species composition consistent with chemical recovery from acidification or, rather, other changing chemical/climatic factors? (iii) Are the species assemblages returning to their pre-acidification state? Post-1995 declines in the relative abundance of diatom and chrysophyte taxa with low pH-optima and increases in taxa with higher pH-optima indicate biological recovery from acidification. In contrast, the cladocera remain unresponsive to post-1995 increases in pH. No species group has returned to its pre-disturbance state and post-ca. 1995 increases in certain taxa (e.g., Synura echinulata ) may be related to recent climate warming in the Adirondacks.