The Effect Of Coal And Mineral Mines On Stream Fishes
Mining operations present a variety of stresses to aquatic environments: they can introduce pollution, contribute to erosion and runoff, alter the paths of water flows, or adversely impact biodiversity. The authors of this study aimed to characterize the impact of coal and mineral mining on fish habitats in three large stream ecosystems: Northern Appalachia, Southern Appalachia, and the Temperate Plains. They assessed these effects by measuring the quantity of mining operations, the density of mining operations, and fish habitat health in the three ecosystems. They also compared these effects against effects of similar but unrelated human-made disturbances, like urban and agricultural land usage.
Fish habitat health was measured by a number of factors incorporating the needs of a variety of different fish. Broadly, these factors included:
- population size of fish who spawn in environments likely to be affected by mining
- population size of fish who prefer environments with fast-moving water
- population size of fish at different levels of the food web
- diversity and consistency of diversity in fish populations
- population size of fish who are sensitive to man-made environmental changes
- population size of fish who are insensitive to man-made environmental changes
- population size of fish whose harvesting is regulated by local state governments
The authors used a mathematical model to predict values for the factors above in a least-disturbed version of the environment. They predicted these values using environmental factors such as area, slope, elevation, precipitation, and groundwater inputs. Once these least-disturbed values were predicted, the authors compared the least-disturbed values to the actual observed values in each of the three ecosystems.
Of all the comparisons between least-disturbed values and actual observed values, 30% of the discrepancies were statistically significant. If a discrepancy was significant at the local scale, a corresponding discrepancy was likely to be significant at the ecosystem scale as well. About half of the significant discrepancies (15% of all comparisons) were found in regions with low mine densities. This suggests that even a single mine can significantly impact the health of stream fish habitats. Approximately 25% of Northern Appalachian streams, 50% of Southern Appalachian streams, and 34% of Temperate Plains streams had nearby mine densities with the potential to affect fish habitat health.
The authors noted that the fish habitat health factors that were most sensitive to mining were indicative of the broader ecological impacts of mining. These sensitive metrics are known to indicate degradation in water quality, alterations in habitat and the food web, changes in community structure, and impacts from sedimentation.
In conclusion, the authors restate that even a single mine can act as a source of stress for stream fishes, and that important cultural or ecological sites should be mine-free. Mines can stress stream environments just as urban land use and agriculture do, and further research is needed to identify ways that mines may be influencing stream fishes. Agencies and managers can use this information to spur action to mitigate the impact of mining, and to restore and preserve existing stream environments.