Blood cell morphology of the Mediterranean pond turtle (Mauremys leprosa Schweigger, 1812) from contrasting habitats in northeastern Algeria

Abstract

We examined the blood cell profiles of the Iberian pond turtle, also known as the Mediterranean pond turtle (Mauremys leprosa) in two habitats in northeastern Algeria with markedly contrasting water quality. Blood smears were prepared from 38 adult turtles collected at a polluted reference site (Bouhamra) and an unpolluted site (Brabtia). Differential leukocyte counts and erythrocyte morphometrics (length, width, and surface area) were quantified. At Brabtia Reserve, heterophils were the most abundant leukocyte type (41.35%), followed by lymphocytes (27.54%) and monocytes (10.16%). At the Bouhamra site, heterophils are also dominant (57.86%), followed by monocytes (21.40%) and lymphocytes (12.80%). The average ratio of heterophils to lymphocytes (H/L) was 4.39 in the polluted site, Bouhamra, which is about three times higher than the ratio of 1.60 in the pristine, indicating elevated physiological stress. Erythrocyte dimensions differed significantly between sites. In turtles from Brabtia, mean erythrocyte length, width, and surface were 24.10 µm, 13.68 µm, and 260.97 µm², respectively. Corresponding values in turtles from the degraded habitat (Bouhamra) were larger (25.07 µm, 13.96 µm, and 274.95 µm²). Nuclear length, nuclear width, nuclear surface, and nuclear shape index (NL/NW) did not vary between habitats. Our results show that contamination mainly affects the size of red blood cells, while the morphological parameters of the nucleus remain stable. The higher H/L ratio at the polluted site (Bouhamra) also supports the use of leukocyte profiles as solid indicators of chronic environmental stress in freshwater turtles.