Histological alterations as a recommended biomarker in the mussel Mytilus platensis (Bivalvia, Mytilidae) to study anthropic impact on seaports

Abstract

Toxic effects of trace metals on digestive gland and gill cytoarchitecture were studied in the mussel Mytilus platensis after metal detection in the environment. Mussels were collected from the Port of San Antonio Este and from a reference site called Isla Mejillón, both in Rio Negro province (Argentina). Histological techniques, morphometrical analysis and lipofuscin detection with Nile blue method were performed. Mussels from the seaport presented dilated hemolymphatic vessels with numerous hemocytes in the gill filaments and fused filaments in the frontal zone. Morphometric analysis of the gill filaments showed an increase in the epithelial thickness of the lateral zone that bears cilia, and we infer that water filtering might be affected. The sublateral zone was also thickened, probably interfering with gas exchange. A reduction in the abfrontal zone epithelial thickness was also noticed, so water pumping, lubrication and cleaning of the gills might be impaired. Digestive glands of seaport mussels accumulated lipofuscin granules within the digestive cells, accounting for lipid and protein peroxidation. The observed histological alterations in gill and digestive gland in mussels from North Patagonia seaport are relevant findings to be considered as biomarkers of effect after exposure to metals.