Ecological monitoring of inter-tidal mudskipper fish of the Bandar Abbas coasts by using the novel epidermal histological index

Aquatic organisms respond to environmental stresses through physiological and morphological adaptations. Accordingly, benthic fish such as the Mudskippers are often referred as bioindicators or sentinel species of aquatic ecosystems such as mangrove forests and mudflats. In the present study, during sampling from three coastal areas of Bandar Abbas (Khorabi, Khajeh Ata and Soro estuary), three species of mudskippers, Periophthalmous waltoni, Boleophthalmus dussumeri and Scartelaos tenuis were identified. Histological studies in mudskippers have focused on the epidermis of the skin by using general staining (hematoxylin-eosin method) and specific staining (periodic acid-Schiff (PAS)-Alcian Blue (AB))‌ approach. The results showed that the thick epidermis is a common feature of the epidermis in all three species of mudskippers and is generally due to layers of the voluminous swollen cells of the skin, development of blood capillary within the epithelium and dermal bulges (except P. waltoni). Mucosal cells were only observed in B. dussumeri and S. tenuis. In P. waltoni, which lived mainly in semi-arid supratidal zone, except for the fins, the whole body is covered with scales, but in the subtidal species of B. dussumeri, the scales are limited to the upper and dorsal, thoracic and caudal stems, and on the skin surface of the intertidal species of S. tenuis, no scales were observed. The results showed species-specific patterns of mudskippers tidal habitat differentiation, based on the epidermal scales as histological ecological indicator.