Biodiversity of an unknown New Zealand habitat: bathyal invertebrate assemblages in the benthic boundary layer

Abstract

For the first time in New Zealand waters, marine invertebrate assemblages from the benthic boundary layer were sampled as part of a broad scale national biodiversity programme, Ocean Survey 2020. Macrobenthic assemblages were collected from ∼1 m above the seafloor at 16 sites on the Chatham Rise and five sites on the Challenger Plateau to the east and west of New Zealand. Depths ranged from 218 to 1,239 m. Nearly 80 000 individual organisms were caught and identified to 33 higher taxonomic groups. Taxa of the supra- and epibenthos as well as taxa with suprabenthic affinities were encountered. Relative abundance and taxonomic richness of the invertebrates between the Chatham Rise and the Challenger Plateau were compared. The crustacean superorder Peracarida proved to be a good group to be representative for abundance patterns of the benthic boundary layer. The peracarid order Tanaidacea was identified to species level, showing high species richness, with 77% of the species being new to science. The observed high levels of biodiversity and high abundances, particularly of copepods and peracarid crustaceans, suggest that this component of the marine fauna, in the benthic boundary layer plays a significant role in ecosystem functioning of New Zealand waters.