Meeting Abstract

P3.18  Tuesday, Jan. 6  Effects of road deicers on survival and behavior of larval and adult wood frogs HAZARD, L.C.*; KWASEK, K.M.; Montclair State Univ., NJ; Montclair State Univ., NJ hazardl@mail.montclair.edu

Use of road deicers (primarily NaCl) in the northeastern U.S. has increased dramatically over the last century. Salts applied to roads can travel considerable distances from the site of application, and may contaminate local watersheds to levels above 100 mM. Amphibians that breed in vernal pools early in the spring, when salt levels could still be high, may be especially vulnerable to increased salinities. We integrated responses of larval and adult wood frogs (Lithobates sylvaticus) to increased salinity to determine whether adult frogs would be able to detect and avoid salinities that would be detrimental to them or to their offspring. Tadpoles were raised in groups at concentrations ranging from 0-200 mM NaCl. No tadpoles at higher concentrations survived to metamorphosis. At low salinity, tadpoles had slightly higher mortality and lower growth and development rates than control animals. Adult frogs were mildly dehydrated to induce thirst, then placed in a shallow dish of water ranging from 0-500 mM NaCl. Location (in or out of the dish) and behavior (moving, standing, sitting, or water absorption response) were recorded during a 10-minute trial. In contrast to arid-adapted anuran species, the wood frogs showed no aversion to salt, remaining in even 500 mM NaCl for the full 10 minutes. Mass loss during the 10-minute trials increased with increasing salinity. The results have important ecological implications. Tadpoles showed sublethal effects even at relatively low concentrations and high mortality at higher concentrations, but adult wood frogs may not be capable of evaluating the salinity of potential breeding sites, leaving this species potentially vulnerable to increased mortality or subtler sublethal effects due to road salt runoff.