First Study on Marine Heterobranchia (Gastropoda, Mollusca) in Bangka Archipelago, North Sulawesi, Indonesia

Abstract

As ephemeral, benthic, secondary consumers usually associated with sessile coral reef organisms, marine heterobranchs are good indicators of the health of marine tropical habitats. Thus, marine Heterobranchia have recently become a major target for monitoring programs. For this work, an extensive survey was made in Bangka Archipelago, the first of its kind in this area. Bangka Archipelago is composed of small islands and the adjacent coastline of North Sulawesi. The substrate is dominated by biogenic reefs and volcanic rocks, thus forming highly diverse habitats. In total, 149 species were collected and/or photo-documented in September 2017 and September 2018, which represents the dry season. They can be assigned to the Cephalaspidea, Aplysiida, Pleurobranchida, Nudibranchia, and Eupulmonata. Thirty-three species are new to science, highlighting the lack of knowledge about the group and especially about this region. Our data provide a baseline for future monitoring surveys, as the anthropogenic pressures on Bangka Archipelago are increasing due to enhanced touristic activities, but also due to large scale environmental changes caused by previous mining operation activities.