Effect of copper on the ultrastructure of the gill epithelium of Carcinus maenas (decapoda: Brachyura)

The epithelial layer of posterior gill number 8 of the common shore crab Carcinus maenas (L.) is made up of three cell types (striated, chief and pillar). Striated cells, with an extensive network of apical and basal infoldings and large numbers of mitochondria, are implicated in ionic regulation. Chief cells contain less plasma membrane infoldings than striated cells, but have a large surface area to volume ratio, implying a predominant role in respiratory gas exchange. The ultrastructural features of pillar cells resemble those of the surrounding epithelial cell type. Thus, pillar cells may play a role in ionic regulation or respiratory gas exchange; however, pillar cells contain a well developed microtubular network, suggesting they also aid structural support and the flow of haemolymph through the gill lamellae. A sublethal copper concentration (50 μg l−1) administered at 35‰ and 10‰ salinity in a flow-through system caused extensive ultrastructural alteration to the gill epithelial cells, including a decrease in the number of plasma membrane infoldings (and associated mitochondria); extensive vacuolation; a change in ribosomal distribution; and disruption of the microtubular network. The extent of the changes was greater at 35‰ than at 10‰ salinity. This paper describes these gill effects in detail, and correlates the ultrastructural changes to previously documented physiological responses of crustaceans exposed to sublethal copper concentrations.