Epibiont of venus clam (Gafrarium tumidum) shells: a study on Pari Island, Seribu Islands

Abstract

Molluscs play a crucial role as ecosystem engineer by providing habitat for other organisms. However, little is known about the shells’ ability to host other species, especially in tropical ecosystems like Pari Island. In sandy locations, hard substrates are scarce, but clam shells introduce substrate heterogeneity. Our study focused on the Venus Clam (Gafrarium tumidum), prevalent in the seagrass bed ecosystem on Pari Island, to explore the epibiont species residing on its shells. Epibionts were examined through visual observation and microscopy analysis in a laboratory. We found the attached epibionts were categorized into three main groups. The first group was macroalgae, specifically Padina sp., which attached to the posterior part of the clam shell, relying on stable substrates to withstand waves. The second group encompassed microalgae, including Bacillaria, Nitzchia, Prorocentrum, Pseudo-nitzschia, Surirella, and Trichodesmium. These microalgae have diverse ecological roles, including causing harmful algal blooms and nitrogen fixation. The third group consisted of possibly cyanobacteria forming blue-green biofilms on clam shells, predominantly on recently deceased or living clams, mainly in exposed, sunlit areas. This research emphasizes the significant role of clam shells in supporting epibiont species richness in the ecosystem.