A preliminary study of the sponge fauna of Orchid island: denizens of pool-cave-canyon systems

Abstract In the present study, we describe elements of the sponge fauna sampled from unique pool-cave-canyon systems at a remote island off the southeastern coast of Taiwan. 22 demosponge species are described of which 10 are new to science, and possibly endemic. Prokaryotic communities were obtained from all species in addition to sediment. What makes the present study unique is that we were able to sample several understudied sponge taxa, e.g., sclerosponges and lithistids, across a relatively small spatial scale. We present the first prokaryotic community analysis of 10 species new to science in addition to Vetulina incrustans, Sollasipelta ornata, Petrosia corticata, Acanthostylotella cornuta, several lithistid species, two phototrophic sponges, and the sclerosponges Acanthochaetetes wellsi, and Astrosclera willeyana. All cave sponges were enriched with SAR202 members, a group of bacteria involved in the degradation of recalcitrant compounds. We suggest that the cave sponges may play a hitherto unexplored role in nutrient dynamics at the land-sea interface. We also encourage surveys of potentially similar systems in Japan and the Philippines. The sponges sampled here also are only a fraction of the total sponge fauna. When surveyed the system appeared to be in good health. Potential threats include large groups of tourists visiting the pools and the presence of a nuclear waste storage facility directly abutting the largest of the pool-cave-canyon systems.