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EVALUATION OF MACROINVERTEBRATE TRENDS IN STREAMS VULNERABLE TO ACID DEPOSITION IN THE MID-ATLANTIC HIGHLANDS REGION OF THE U.S.A.
Citation:
Klemm, D J., K A. Blocksom, A. T. Herlihy, AND W T. Thoeny. EVALUATION OF MACROINVERTEBRATE TRENDS IN STREAMS VULNERABLE TO ACID DEPOSITION IN THE MID-ATLANTIC HIGHLANDS REGION OF THE U.S.A. Presented at Society of Environmental Toxicology and Chemistry, Austin, TX, November 8-13, 2003.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
Benthic macroinvertebrate and water chemistry samples were collected from wadeable stream sites in the Mid-Atlantic Highlands region of the U.S. during 1993-1995 and 2001 in support of USEPA's TIME (Temporally Integrated Monitoring of Ecosystems) Progam. This study was designed to measure the effects of acid deposition and the long-term trends at sites sensitive to acid deposition in response to emission reductions associated with the 1990 Clean Air Act Amendments. An ordination of stream sites using 1993-1995 macroinvertebrate species abundance data showed a strong pH gradient and clear separation between sites vulnerable and non-vulnerable to acid deposition. When these sites were assigned to five acid sensitivity classes based on acid neutralizing capacity, those in the chronically and episodically acidic classes had lower scores of the Macroinvertebrate Biotic Integrity Index (MBII). The more sensitive classes had fewer caddisfly and mayfly taxa, as well as lower collector-filterer taxa richness and a higher percentage in the 5 dominant taxa. Between 1993-1995 and 2001 at sites vulnerable to acid deposition, MBII scores improved by an average of 15 points on a 100-point scale. These increases in index scores reflected increases in mayfly, caddisfly, and collector-filterer richness and decreases in the percent dominant 5 taxa.