Monitoring Physiological Responses in Giant Toad (Rhinella marina) from Coatzacoalcos, Mexico: A Comparative Study after 8 Years

Abstract

The objective of this chapter is to present the results of a monitoring study carried out with physiological responses (biomarkers) in Rhinella marina (giant toad) for two different years, inhabiting the low basin of Coatzacoalcos river, one of the most contaminated regions in Mexico. A decrease in delta aminolevulinic acid dehydratase (δ-ALAD) (considered inhibi- tion) and in the condition factor (1.2–1.5 times) found in toads of the industrial zone compared with reference organisms, each year. As for the hematological parameters, the mean corpus- cular hemoglobin concentrations (MCHC), in the amphibians of industrial zone of the first sampling year show a decrease, while for the second sampling year, show an increment of 1.5 times than organisms of reference site. These effects could be associated with exposure to pollutants such as heavy metals (mainly Pb), which have been registered in different studies. This study demonstrates the usefulness of giant toads as biomonitors of contaminated sites.