Successful Eurasian watermilfoil (Myriophyllum spicatum L.) management requires the ability to rapidly establish the presence and relative abundance of the plant. Using hydroacoustics (BioSonics DT-X equipped with a 430-kHz transducer), we have developed a method to quickly survey the littoral zone for the presence of Eurasian watermilfoil. The algorithm developed to interpret hydroacoustics data makes it possible to distinguish Eurasian watermilfoil from native species. Physical growth parameters, including depth, lateral extent, percentage of water column occupied by the plant, and other parameters are used to locate or identify the plant based upon hydroacoustics data. After establishing the ability to accurately identify milfoil quickly and effectively, the method was utilized in 5 bays in the southern end of Lake George, New York. Survey results identified 6 previously unknown Eurasian watermilfoil sites and confirmed the existence of an additional 10 known locations.

The Adirondack Mountains in New York State have a varied surficial geology and chemically diverse surface waters that are among the most impacted by acid deposition in the U.S. No single Adirondack investigation has been comprehensive in defining the effects of acidification on species diversity, from bacteria through fish, essential for understanding the full impact of acidification on biota. Baseline midsummer chemistry and community composition are presented for a group of chemically diverse Adirondack lakes. Species richness of all trophic levels except bacteria is significantly correlated with lake acid-base chemistry. The loss of taxa observed per unit pH was similar: bacterial genera (2.50), bacterial classes (1.43), phytoplankton (3.97), rotifers (3.56), crustaceans (1.75), macrophytes (3.96), and fish (3.72). Specific pH criteria were applied to the communities to define and identify acid-tolerant (pH<5.0), acid-resistant (pH 5.0-5.6), and acid-sensitive (pH>5.6) species which could serve as indicators. Acid-tolerant and acid-sensitive categories are at end-points along the pH scale, significantly different at P<0.05; the acid-resistant category is the range of pH between these end-points, where community changes continually occur as the ecosystem moves in one direction or another. The biota acid tolerance classification (batc) system described herein provides a clear distinction between the taxonomic groups identified in these subcategories and can be used to evaluate the impact of acid deposition on different trophic levels of biological communities.