Multimetric indices based on fish and benthic macroinvertebrate assemblages are commonly used to assess the biological integrity of aquatic ecosystems. However, their response to specific stressors is rarely known. We quantified the response of a fish-based index (Mid-Atlantic Highlands Index of Biotic Integrity, MAH-IBI) and a benthic invertebrate-based index (West Virginia Stream Condition Index, WV-SCI) to acid mine drainage (AMD)-related stressors in 46 stream sites within the Cheat River watershed, West Virginia. We also identified specific stressor concentrations at which biological impairment was always or never observed. Water chemistry was extremely variable among tributaries of the Cheat River, and the WV-SCI was highly responsive across a range of AMD stressor levels. Furthermore, impairment to macroinvertebrate communities was observed at relatively low stressor concentrations, especially when compared to state water quality standards. In contrast to the WV-SCI, we found that the MAH-IBI was significantly less responsive to local water quality conditions. Low fish diversity was observed in several streams that possessed relatively good water quality. This pattern was especially pronounced in highly degraded subwatersheds, suggesting that regional conditions may have a strong influence on fish assemblages in this system. Our results indicate that biomonitoring programs in mined watersheds should include both benthic invertebrates, which are consistent indicators of local conditions, and fishes, which may be indicators of regional conditions. In addition, remediation programs must address the full suite of chemical constituents in AMD and focus on improving linkages among streams within drainage networks to ensure recovery of invertebrate and fish assemblages. Future research should identify the precise chemical conditions necessary to maintain biological integrity in mined Appalachian watersheds.

Radio telemetry is commonly utilized in large, deep bodies of water to assess fish movement and habitat use. A commonly neglected factor in these studies is the influence of signal attenuation on the results and conclusions. Signal attenuation is related to many factors but most importantly to the depth of the transmitter in the water column and water conductivity. While conducting a biotelemetry study within the Ohio River, several fish that had not been detected in prior search periods were detected in later searches. Consequently, we hypothesized that telemetered fish in deep water may not be detected. We conducted an experiment to measure the influence of depth on the maximum distance at which a transmitter could be detected and found that an exponential decay model (distance = 0.9890 × e(0.2005 × depth)) best explained these data. Our results imply that radio telemetry studies may underestimate use of deepwater habitats by fishes.

Multimetric indices based on fish and benthic macroinvertebrate assemblages are commonly used to assess the biological health of aquatic ecosystems. However, the response of biological indices to specific stressor levels is rarely known. I quantified the relative response of a fish-based index of biotic integrity (IBI) and a benthic macroinvertebrate-based index to acid mine drainage related stressors in the Cheat River watershed, West Virginia. Fish and benthic macroinvertebrate assemblage data (% taxon composition) were used to calculate Mid-Atlantic Highland Assessment Index of Biotic Integrity (MAHA-IBI) and West Virginia Stream Condition Index (WV SCI) scores for each site. Both MAHA-IBI and WV SCI scores were scaled by dividing all scores by the highest value observed in the watershed. Water chemistry was dominated by constituents indicative of AMD. Both fish and macroinvertebrate assemblages responded to water chemistry parameters and principal component analysis (PCA) factor scores that summarized covariance among water chemistry parameters. Macroinvertebrate assemblages were more responsive to chemical stressors from AMD than were fish assemblages. However, in many cases information from macroinvertebrate and fish multimetric indices provided complementary information, presumably because fish assemblages are responsive to regional conditions, and invertebrates are more responsive to local conditions. Results suggest that monitoring programs and prioritization of mine discharge treatment need to consider biological response to mining-related water chemistry impairment.

Headwater streams derive a majority of their energy from allochthonous inputs; alteration of these inputs may lead to changes in stream communities and ecological function. Common buckthorn (Rhamnus cathartica) is invasive over much of the northern United States and southern Canada, and has the potential to become an ecosystem dominant and alter stream communities. However, while much is known of the effects of buckthorn on terrestrial ecosystems, little is known of its effects on aquatic ecosystems. Using leaf collection nets, we estimated that leaf fall to the stream consisted predominantly of green ash (69.0%) and common buckthorn (24.2%). Green ash leaves fell from September through mid-October, reaching its peak in early October, whereas common buckthorn contributed leaves for an additional month until mid-November. We placed leaf packs of common buckthorn and two native species, American elm and green ash, in a headwater stream to determine differences in leaf decomposition rates. Common buckthorn leaves decomposed more rapidly than the native species, with processing coefficients of 6.9 (ash) and 5.3 (elm) times greater. After 21 days of incubation, buckthorn leaf packs had less than half the initial biomass remaining, whereas ash and elm did not reach this point within this 84-day study. These results suggest that buckthorn has the potential to alter stream food webs by changing the timing of leaf fall and the duration of available allochthonous energy sources. Changes to riparian forests are likely to be exacerbated as common buckthorn alters soils to inhibit the growth of other trees and as the emerald ash borer, an invasive beetle, adversely affects native ash forests.