Acidification of lotic and lentic environments has been found to adversely affect the integrity of resident biological assemblages. These effects have been particularly severe in poorly buffered regions like the Western Adirondacks. Although the Clean Air Act and its amendments have greatly reduced levels of atmospheric deposition, many streams in this region are still chronically or episodically acidified. In-stream and watershed-wide liming are two directed-mitigation techniques which could be used to accelerate ecosystem recovery and help restore the condition of biological assemblages. The costs and abilities (as well as effective duration) of these techniques to improve water and soil chemistry, tree health, and the condition of aquatic and terrestrial ecosystems are currently being assessed in several tributaries and watersheds of Honnedaga Lake in the Western Adirondacks as part of an ongoing Accelerated Recovery Study.The study outlined herein will assess the condition of benthic macroinvertebrates in limed and reference (control) tributaries to Honnedaga Lake. Benthic macroinvertebrates serve as an important linkage between allochthonous inputs of nutrients and aquatic consumers in higher trophic levels (e.g., the health of native brook trout populations). The condition of macroinvertebrate assemblages is commonly used to monitor and assess the general health of natural aquatic systems and the quality of surface waters. This information will help define and interpret the: (a) effects of reduced stream acidification (and indirectly - acidic deposition) on aquatic ecosystems, (b) direct effects of recovery from acidification on stream food webs, (c) resultant changes in energy/nutrient transfers across trophic levels, and (d) indirect effects of improved water quality (via changes in food resources) on the health of resident brook trout populations.
The primary objective of this study is to evaluate the effectiveness of two alternative accelerated recovery techniques (watershed and in-stream liming) to improve the health of macroinvertebrate assemblages in acidified tributaries of Honnedaga Lake.
This project will build on several sets of previously collected macroinvertebrate community samples. Macroinvertebrates were sampled at six sites using rock baskets by Colgate researchers in 2012 and by the U.S. Geological Survey (USGS) in 2013 and 2014. Rock baskets simulate natural stream substrate and are left on the stream bed for two months, during which time they are colonized by benthic organisms. Researchers then extract the macroinvertebrates that colonized the substrate. The USGS will continue using this method to collect macroinvertebrate samples during 2015 and 2016. The collected organisms are identified to species and used to compute metrics or indices of stream condition. These metrics, in addition to multivariate statistical techniques, will be used to determine if differences exist in macroinvertebrate communities between treated and reference sites or between treatment types.