First insights into the phylogeny of deep-sea glass sponges (Hexactinellida) from polymetallic nodule fields in the Clarion-Clipperton Fracture Zone (CCFZ), northeastern Pacific

Abstract

Glass sponges represent a dominant group of megabenthic deep-sea fauna and play a key role in benthic deep-sea ecosystems. Especially in the Clarion-Clipperton Fracture Zone (CCFZ), a potential deep-sea mining area, they grow on polymetallic nodules or on the surrounding sediment. We investigate hexactinellids from the CCFZ to understand the ecological aspects of deep-sea mining and support the development of future pre-mining risk assessments and monitoring actions. Therefore, this study is published as part of a series of studies, all focusing on deep-sea glass sponges from the CCFZ. Resolving genetic relationships between species is still a fundamental as well as challenging task. Especially understudied groups mostly lack resolution. Combining results derived from taxonomic and phylogenetic data gives deeper insights into glass sponge relationships. Here, we present (1) a set of new primers for sequencing mitochondrial 16S rDNA as well as nuclear 18S and 28S rDNA of glass sponges, (2) first DNA sequencing data for 6 hexactinellid genera and 19 species, as well as (3) the most comprehensive phylogenetic tree of hexactinellid sponges to date including data available from previous studies.