Biodiversity of Marine Heterobranchia (Gastropoda) around North Sulawesi Indonesia

Abstract

North Sulawesi province is one of the most potential areas in terms of natural marine resources. In North Sulawesi there are many interesting tourist places with high marine biodiversity and many objects are currently under development, including Bunaken National Marine Park (BNP), Lembeh strait, in the island of Sangihe, and Bangka archipelago. Coastal areas of North Sulawesi are considered as the most diverse habitats in the world with high species diversity in coral reefs, but also in adjacent sea grass beds and mangroves. The high diversity also includes marine heterobranch sea slugs, which are known by an extremely large number of species of up to probably 2000, with many undescribed ones. My study in Sangihe Island is the first survey of marine heterobranch around this island and included in the collection 23 species, with Phyllidiidae show the highest dominance (Chapter 3). The amount of species is far lower than in the studies around BNP, or the Bangka Archipelago. The Chromodorididae is a large and colourful family of nudibranch sea slugs distributed across the tropical and temperate world’s oceans. These sea slugs are known by many divers because of their beauty and by many pharmacists because of their high diversity in natural compounds. For studying the Chromodorididae, 375 specimens were collected around North Sulawesi in 2015, 2016 and 2017. Chapter 4 and chapter 5 focus on this family Chromodorididae. The phylogenetic hypothesis based on two mitochondrial genes, CO1 and 16S, is the only subsequent study after the first study published in 2012 by Johnson & Gosliner. The major result of my analyses is the confirmation of the results obtained by Johnson & Gosliner 2012 at that time. Chromodoris is a genus of colourful nudibranchs that feed on sponges and is found across the Indo-Pacific. Chapter 5 in this study focuses on these species of the genus Chromodoris (i.e. C. annae, C. dianae, C. willani, C. lochi) of which hundreds of specimens were collected. The results about Chromodoris species clearly show wide spread cryptic speciation The results with regard to water quality, indicate that all sampling points are within the range of normal values and no specific pollution can be seen (Chapter 6).