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Microscopic epibionts on molluscan shells are a component of the biodiversity of intertidal coastal areas. Because molluscan shells are discrete habitats for the epibiont community, and the molluscan basibionts belong to the local community, epibiont diversity can be evaluated hierarchically by basibiont categories including species. To evaluate the structure of epibiont diversity and effects of taxonomic resolution on the evaluation, epibionts on molluscan shells and inert surfaces were investigated at three geographically distant sites in Japan. In total, 94 species-level taxonomic units of epibionts were obtained from 31 basibiont molluscan species and inert surfaces (plastics and rock chips). The density and the species richness at the site of the lowest latitude were significantly lower than those at the other sites. The epibiont community differed between the three sites, although the major portion of the epibionts were diatoms. Between-site diversity contributed most of the total diversity of the species richness and Simpson diversity in the five levels of the hierarchical partitioning: sample (individual basibiont), basibiont species (molluscan species), surface group (bivalves, chitons + limpets, and globose gastropods), site, and the total. The taxonomic resolution did not markedly affect the variability of communities between the three sites, although the taxon richness was reduced to 51 in the genus-level analysis. The lower taxonomic resolution (genus level); however, increased the contribution of the within-sample and decreased the contribution of β diversities at the higher hierarchies, leading to a possible overestimation of biotic homogenization between the communities., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Bacterial attachment and growth on material surfaces are considered to be the primary steps leading to the formation of biofilm. Biofilms in hospital and food processing settings can result in bacterial infection and food contamination, respectively. Prevention of bacterial attachment, therefore, is considered to be the best strategy for abating these menaces and therefore the development of antibacterial metals becomes important. In this study, nine pure metals, viz. titanium, cobalt, nickel, copper, zinc, zirconium, molybdenum, tin, and lead have been tested for their antibacterial properties against two bacterial strains, Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. This was accomplished using two assay methods, the film contact method and the shaking flask method. The results show that the antibacterial properties varied significantly with different metals and the effectiveness of metals to resist bacterial attachment varied with the bacterial strain. Among the metals tested, titanium and tin did not exhibit antibacterial properties. TEM images showed that metal accumulation resulted in the disruption of the bacterial cell wall and other cellular components.