Use of Haematological Indicators in Anurans for Assessing Their Health Status When Inhabiting Conditions of Anthropogenic Stress. Pelophylax ridibundus (Amphibia: Ranidae) as an Example: A Review and Appraisal

We review evidence for and against the use of haematological parameters as indicators for assessing the health status in free-living anuran populations that live in conditions of ecological stress. We focus on the use of direct measured blood parameters, such as erythrocyte and leukocyte counts, haemoglobin concentration, haematocrit value, leukogram and calculated haematological indexes: mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and mean corpuscular volume. In addition, we evaluate the possibilities for use as biomarkers of the metric parameters of erythrocytes. This paper summarizes the results from our long-year in situ analyses of the populations of Marsh frog P. ridibundus inhabiting freshwater ecosystems in Southern Bulgaria with different degrees of anthropogenic transformation. It presents the results from using different haematological indicators as markers for the assessment of changes in their organism when inhabiting areas affected by anthropogenic stressors. Our results strongly support using blood changes in anuran amphibians as objective indicators for assessing their health status. We believe they are a reliable biodiagnostics instrument in modern in field ecotoxicological studies.