Abstract
In this study, histological, ultrastructural, and immunohistochemical observations of the gill tissue of two fish species (Plagioscion squamosissimus and Lithodoras dorsalis) were used as biomarkers to assess the ecological conditions of an estuary in the Amazon delta, by relating the health status of the fishes to environmental quality. The gill tissue was analyzed both qualitatively and semi-quantitatively. Marked differences in the type and severity of lesions were verified between species and among study sites. A variety of severe damages were confirmed histologically in specimens from the two impacted areas (B and C), including aneurysms, epithelial lifting, and intense hyperplasia. Electron microscopy and immunohistochemical analyses also revealed injuries in the gill tissue of specimens from these two areas. While, on area A only few specimens showed mild changes in gill tissues and rare marking of apoptosis. These results confirm the urgent need for the more effective control of the discharge of pollutants into the estuary as well as more effective urban planning, given the close proximity of a major industrial complex to residential areas.
Highlights
The main causes of the degradation of aquatic systems are siltation and the dumping of pesticides and domestic and industrial waste, activities that may cause highly detrimental changes in the physical, chemical and biological characteristics of water (VAN SICKLE et al, 2006; KANU; ACHI, 2011)
This study investigated the occurrence of morphological and immunohistochemical alterations in the branchial tissue of two fish species – Plagioscion squamosissimus (Heckel, 1840), a carnivore, and Lithodoras dorsalis (Valenciennes, 1840), a detritivore – which were used as biomarkers for environmental impacts
The normal macroscopic morphology was observed in all the specimens studied, there were differences in the morphology of the gill rake, which was much sparser in L. dorsalis in comparison with P. squamossissimus
Summary
The main causes of the degradation of aquatic systems are siltation and the dumping of pesticides and domestic and industrial waste, activities that may cause highly detrimental changes in the physical, chemical and biological characteristics of water (VAN SICKLE et al, 2006; KANU; ACHI, 2011). Effective control of these problems require the continuous monitoring of environmental quality and for this, the biological responses (biomarkers) of. Immunohistochemical and histological biomarkers are excellent tools for the assessment of environmental impacts
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