Effects of nitrate on tissue level biomarkers in post-metamorphic xenopus laevis

Abstract

Amphibian populations have been declining globally since the 1980's. Threats putting the populations at risk include global warming, habitat or land-use changes (including increased nitrogen application), emerging infectious disease, invasive and exotic species, ultra-violet radiation, and toxicants such as those used in agricultural practices. The effect of these stressors on amphibian population include not only decline in abundance but also developmental deficiencies in growth rate, behavioral, and morphological abnormalities. The study presented in this paper, focuses on potential tissue level biomarkers of nitrogen exposure. The use of a chronic exposure during multiple critical developmental periods at ecologically relevant levels of nitrate will produce data that reflects the resilience or the susceptibility of the frog, Xenopus laevis. Measures of fluctuating asymmetry, hematocrit, body condition, and metamorphic data were collected and analyzed to determine the effect of nitrate on Xenopus laevis. The results of this study largely determined no significant difference between treatments for the bioindicators measured when Xenopus laevis were exposed to nitrate from hatching to two-months post metamorphosis. These suites of tests are important to literature for two primary reasons 1) substantiation of the water quality test reinforces the quality of the test and tight controls in place 2) the length of chronic exposure in a multi-factorial test.