From the mountaintops to the streams: Mountaintop removal mining threatens salamander populations
Primary article: Hutton, J.M et al. Occupancy and abundance of stream salamanders along a specific conductance gradient. Freshwater Science. 2020. 39(3): 433-446. doi: 10.1086/709688.
Mountaintop removal: consequences flow downstream
In mountain-top removal mining, forests are cleared, then explosives detonated to destroy the mountain and expose coal seams underneath. The waste is often disposed of in nearby valleys, suffocating small headwater streams.
The waste can cause changes in the concentration of ions in the water far downstream. As a result, streams adjacent to mountain-top removal have been documented to have higher levels of specific conductivity (a measure of ions in the water) than those that are not affected by mountain-top removal. These higher levels of conductivity have known effects on species distributions and abundance.
Streams are home to an abundance of flora and fauna. One of the shyest and most charismatic of these is salamanders, which are uniquely diverse and abundant in the United States. They can be difficult to spot and are often overlooked, but they play crucial roles in the food chain by consuming insects and providing prey for larger animals. They are also uniquely vulnerable. As amphibians, they belong to the world’s most endangered vertebrate group. Their permeable skin allows oxygen to enter their circulatory systems, but it also means that toxins can easily be absorbed. As a result, salamanders can tolerate only relatively pristine habitats, and their presence and abundance can be indicators of ecosystem health (USGS).
Examples of salamanders found in Kentucky (clockwise starting from top): Northern Slimy Salamander (Nick Scobel, Flickr), Northern Red Salamander (R. Russel Beatson , Flickr), Green Salamander (R. Russel Beatson, Flickr), and the Yellow Spotted Woodland Salamander (Jake Scott, Flickr).
Salamander study
A team of Kentucky scientists aimed to further elucidate the link between mountain-top removal and salamanders, as well as the link between specific conductivity and other chemical and physical habitat characteristics, including pH, leaf litter abundance, temperature, tree cover. They surveyed ten streams with high specific conductivity due to their proximity to mining sites, ten with intermediate conductivity, and ten with low conductivity. A water sample was taken from each site and a salamander search commenced within a ten-meter stretch at each stream. Salamander species identity and numbers were recorded.
Scientists found that salamander occupancy (whether or not they were present in a given stream) and abundance both decreased as specific conductivity increased, suggesting that the conductivity changes caused by mountain-top removal and valley filling pose a threat to salamanders.
How do ion changes harm salamanders?
Salamanders aim to maintain a lower concentration of ions inside their bodies than that of the environment outside their bodies through a process called osmoregulation. Higher specific conductivity means that the environment has a higher concentration of ions entering the salamander’s body, which means they need to spend an ever-increasing amount of energy on osmoregulation, leading to increased stress and mortality. Higher specific conductivity may also result in hungrier salamanders, as it is associated with a decline in macroinvertebrates, which are key salamander prey. In this study, the macroinvertebrates’ food (leaf litter) increased with increasing specific conductivity, providing further support for this line of thought.
The evidence suggests that the specific conductivity changes resulting from mountain-top removal and valley filling are harmful to salamanders.
To learn more about the human and environmental tolls of mountaintop removal, and how you can help, visit ilovemountains.org.
To learn more about salamanders and how you can help protect them, visit Save the Salamanders.
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