Blood δ-ALAD, lead and cadmium concentrations in spur-thighed tortoises (Testudo graeca) from Southeastern Spain and Northern Africa

Mediterranean spur-thighed tortoise (Testudo graeca) is actually included in the IUCN as vulnerable species. Its main European population is located in southeastern Spain. Although a great deal of information has been acquired on the internal medicine and survey and even parasitological fauna on these animals, there are no references about contaminants levels in this species. The objectives of this study were to compare the levels of two metals (cadmium and lead) in the blood of spur-thighed tortoises from two different populations, one from Southeastern of Spain (n = 22) and the other from North of Africa (n = 39), kept in captivity at the Santa Faz Recuperation Centre (Alicante, Spain) and to investigate the relationship between their blood levels of lead and their blood δ-aminolevulinic acid dehydratase (δ-ALAD) activity. Blood lead and cadmium concentrations were higher in tortoises from African than in those from Spain. Moreover, a negative and significant correlation (P < 0.05) was found between δ-ALAD activity and blood lead levels, indicating the suitability of this enzyme as biomarker for lead in this species.