Exploring the Effects of The Clean Air Act on Stream Invertebrate Communities

Abstract:

Acid deposition in the northeastern United States has been recognized as an environmental problem affecting aquatic and terrestrial ecosystems. In an effort to protect these ecosystems, the Clean Air Act Amendments of 1990 were passed to achieve a national standard of ambient air quality by placing restrictions on emissions of nitrogen and sulfur oxide. Long-term pH data at Hubbard Brook Experimental Forest (HBEF) demonstrate that stream pH has increased, however, there is no comparable examination of stream macroinvertebrate recovery. To explore whether stream invertebrate communities have responded to the Clean Air Act Amendments in New Hampshire, we synthesized data from the United States Geological Survey (USGS) and the New Hampshire Department of Environmental Services (NHDES) that contain both pH and stream macroinvertebrate measurements. We identified 11 sites containing both biological and water quality data from USGS from the year 2000, and 154 sites from NHDES ranging from 2003-2017 (biological data) and from 1990-2019 (pH data). Of these sites, 99 of them only have one collection date for aquatic macroinvertebrates, thereby limiting the ability to detect change over time. In addition, 80 percent of the sites did not experience the hypothesized increase in pH as observed at HBEF. Further analysis will evaluate the impacts of pH on aquatic macroinvertebrates using a Threshold Indicator Taxa Analysis (TITAN). Although these data were collected throughout New Hampshire, there is insufficient temporal data to conduct an analysis of the impact of the Clean Air Act Amendments. This study demonstrates that we need to employ ecological monitoring over longer timescales to fully understand how environmental regulations may affect the very ecosystems that they are designed to protect.