Second survey of heterobranch sea slugs (Mollusca, Gastropoda, Heterobranchia) from Bunaken National Park, North Sulawesi, Indonesia - how much do we know after 12 years

Bunaken National Park (BNP) is one of the most famous marine national parks in Indonesia with an
extraordinary diversity in marine life forms. However, this diversity is threatened by an increasing population on the
islands, ongoing destructive fishing techniques and lately by an increase in tourism. Protecting and managing the
future use of BNP resources will require the assessment of both, local marine biodiversity through monitoring
efforts and the identification and subsequent reduction of any threats or changes in the park. A high diversity in
marine Heterobranchia indicates a high diversity of metazoan life forms and a diverse habitat structure. Surveying
the complete biological diversity across taxonomic groups found in BNP would be an extensive undertaking, so
focus on heterobranch diversity as an indicator of coral reef health was initiated and a model group on which
future monitoring and conservation efforts can be based is provided. This study follows up the first investigation
of marine Heterobranchia in BNP, conducted 12 years ago, while assessing molluscan diversity, and intends to
present a base line for future monitoring programs.