The NSS Bulletin - ISSN 1090-6924
Volume 43 Number 1: 12-18 - January 1981

A publication of the National Speleological Society

Acute Toxicity of Cadmium, Zinc, and Total Residual Chlorine to Epigean and Hypogean Isopods (Asellidae)
Arthur D. Bosnak and Eric L. Morgan


Aquatic toxicological assays are typically employed to evaluate the influence of pollutants upon epigean organisms. Little attention has been given to the fate of pollutants in waters which flow though subterranean karst conduits and to their impact upon hypogean communities. This study tests the hypothesis that hypogean organisms would be more sensitive to selected toxic substances than would ecologically similar epigean forms.

During late summer and early fall of 1978, Caecidotea bicrenata, a blind hypogean cave isopod, and Lirceus alabamae, an epigean isopod, were collected from similar hydrological systems and tested under laboratory conditions employing ambient spring wate to establish 96-hour LC 50 values for cadmium, zinc, and total residual chlorine in flow-through toxicological assays. C. bicrenata were taken from Merrybranch Cave, White County, Tennessee, and L. alabamae were taken from a spring-fed stream in DeKalb County, Tennessee.

The resulting 96-hour LC 50 values and their 95% confidence levels for each toxicant were derived by Log-Probit and 10% Spearman-Karber analyses. Evaluation of heavy metal treatments revealed that epigean L. alabamae were more sensitive to toxicants than were hypogean C. bicrenata. In the total residual chlorine treatment, no significant differences between the two species were found in the LC 50 values observed at the 95% confidence level.

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