EFFECTS OF ELEVATED SALINITY ON THE MORPHOLOGY AND BEHAVIOR OF GREEN FROG TADPOLES (LITHOBATES (RANA) CLAMITANS)
Open Access
Author:
Samra, George
Area of Honors:
Environmental Resource Management
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Dr. Jacqualine Grant, Thesis Supervisor Dr. Jacqualine Grant, Thesis Supervisor Robert David Shannon, Thesis Honors Advisor Margaret C Brittingham, Thesis Honors Advisor
Due to extensive use of road de-icers, elevated levels of NaCl have been measured in freshwater bodies associated with roads. At high enough concentrations NaCl causes mortality in anuran larvae. For example, the LC50 for Lithobates clamitans larvae is over 3000 mg/l Cl-. In this study we desired to determine the sublethal effects of NaCl on L. clamitans larvae by measuring the growth and predator escape response of tadpoles raised in 200 and 800 mg/l NaCl. Tadpoles tested after 25 to 28 days of exposure did not differ from control tadpoles. After 148 days of exposure tadpoles raised in the control and 200 mg/l NaCl treatment had significantly smaller masses and lengths than tadpoles in the 800 mg/l NaCl treatment. No differences in escape response were observed in either time period. These results suggest that NaCl levels as low as 800 mg/l could increase growth rate of larval anurans giving them a competitive advantage in avoiding predation. Such a response to elevated salinity could be an adaptation to detect and escape drying ponds.
