Ultrastructure of the gills ciliary epithelium of Limnoperna fortunei (Dunker 1857), the invasive golden mussel

Background: Limnoperna fortunei is a bivalve mollusk originally from southern Asia that invaded South America in the 1990's. Its high efficiency in pumping and filtering water and the capacity to promote strong adhesion to different substrates allowed the adaptation of this invasive species, associated with several environmental and economic damages. A deep understanding of the biology and ecology aspects of L. fortunei is necessary to outline effective strategies to manage its invasion. Mollusk gills are important structures responsible for several biological functions including breathing and feeding. In this work, we characterized the ultrastructure of L. fortunei gills and its ciliary epithelium using transmission and scanning electron microscopy. This is the first report of the L. fortunei gills ciliary epithelial cells visualized with high resolution and detailed morphology. Results: The analysis showed a highly organized and large amount of ciliary structures (frontal cilia, laterofrontal cilia, and lateral cilia) on the entire length of the branchial epithelium. Mitochondria, smooth endoplasmic reticulum and glycogen granules were abundantly found in the epithelial cells of the gills, suggesting that all this energetic apparatus could be related to the morpho-functional structure of the cilia. Vesicles possibly containing mucus could also be observed in these cells, suggesting that they might be related to L. fortunei mechanism of selection and/or rejection of captured particles suspended in water. Conclusions: Our data suggest the mechanism used by this mollusk for particles capture and selection, which could contribute to a better understanding of important aspects of invasion and decide on more efficient and economic strategies of population control.