Metal concentrations of sentinel lycosid spiders inhabiting remediated areas

Abstract

Mining in Butte, Montana, has a history spanning more than 140 years, beginning in the 1880s and continuing to the present. Consequently, the Butte area became covered in mine waste containing high levels of various metals. For nearly 100 years, mining in Butte was conducted irresponsibly and without regulation; the area was ultimately designated a Superfund site in 1984, one of the largest Superfund complexes spanning 140 km (approximately 140 miles) in length. Since then, measures have been taken to secure the mine waste in place and prevent it from interacting with the environment. However, questions remain about the efficacy of these measures. Therefore, to determine whether the waste left in place is not interacting with the environment, I used a sentinel animal taxon, wolf spiders (Family Lycosidae), to evaluate the possible accumulation of these metals in the area. Using pit traps, I caught 51 spiders at three sites throughout Butte and a control site in the Grass Range, Montana. The lycosid spiders caught at these sites were weighed, acid-digested, and run through an inductively coupled plasma mass spectrometer (ICP-MS). This analysis revealed the identity and concentrations of the metal isotopes accumulated in the spiders. The metal content of the spiders was analyzed per site and collectively across all sites. The metals identified with the highest concentrations and abundance across all locations are Mn at 3.1, Cu at 3.17%, Zn at 19.12%, Fe at 27.27%, and Al at 46.10%. This metal content was then compared to the spiders' weight to see if there was a relationship. My results show that the larger the spider, the more metal that was bioaccumulated, and the sites with the waste left in place had higher levels of metals in the spiders. These results demonstrate that wolf spiders may be an effective and reliable sentinel species for the Butte area, indicating potential negative environmental effects and remediation effectiveness.