Investigating the physico-chemical niche of obligate subterranean amphipods and isopods in shallow subterranean waters of the DC metro area

Washington, D.C. is home to a remarkable assemblage of troglomorphic amphipods and isopods living in shallow subterranean habitats that emerge at seepage springs, or "seeps". Species include amphipods (Crangonyx and Stygobromus) and isopods (Caecidotea). One species, Stygobromus hayi, is on the endangered species list and another is soon to be listed; however, little is known about their habitat preferences or their distribution. Seepage springs were sampled in national park lands in the DC metropolitan area for rare subterranean fauna, soil morphology, and water quality indicators such as nitrates, phosphates, radon, pH, DO, and conductivity. Based on a discriminant analysis, the parameters measured in this study were not able to distinguish between stygobiont-rich sites and stygobiont-poor sites. More than 100 seeps have been found in Southeast, D.C., with the highest concentration in Shepherd Parkway. This study points to the potential importance of small parks as reservoirs of biodiversity in low-socioeconomic communities.