First insights into the deep-sea tanaidacean fauna of the Ross Sea: species richness and composition across the shelf break, slope and abyss

Krzysztof Pabis,Magdalena Błażewicz-Paszkowycz,Piotr Jóźwiak,Kareen Schnabel,Anne-Nina Lörz

doi:10.1007/s00300-015-1706-z

Abstract

Tanaidaceans belong to the most severely underestimated groups of benthic macrofauna of the Southern Ocean. Here, we analyze 11 samples collected with a small-meshed epibenthic sled in the summer season of 2008, in the Ross Sea, at the shelf break, slope and abyss (365–3490 m). The material was obtained during a RV Tangaroa voyage as part of the New Zealand International Polar Year, Census of Antarctic Marine Life Project. Seventy-two species of Tanaidacea were recorded, 85 % of which were new to science. The most speciose genera are Typhlotanais, Pseudotanais and Paraleptognathia. Rare species (singletons and doubletons) constituted 60 % of the material. Each of the three studied depth zones was characterized by a unique tanaidacean fauna. Only few species (<6 %) occurred consistently in more than one depth zone. The highest number of species (31 species) was recorded in the abyssal sites, and the lowest number of species (20 species) at the shelf sites.

Highlights

The results of the Census of Antarctic Marine Life (CAML) program have highlighted that a taxonomic inventory of the shelf benthic fauna in the Southern Ocean is still far from complete (De Broyer et al 2011; Griffiths et al 2011, 2014) and that the knowledge on the diversity of benthic communities below shelf depth is especially scarce (e.g., Hilbig 2004; Blake and Narayanswamy 2004; Brandt et al 2007; Kaiser et al 2007, 2011; Post et al 2011; Griffiths et al 2014)
Ingels et al (2012) listed isopods and amphipods among the five major groups in the Southern Ocean that act as key contributors to the Antarctic diversity
The current number of isopod and amphipod species described from the Southern Ocean is higher than tanaidaceans (De Broyer et al 2011), but most recent studies (e.g., Pabis et al 2015) demonstrated that the species richness of the Antarctic shelf tanaidacean fauna is highly underestimated and poorly recognized as that in the deep sea (Brandt et al 2007)

Summary

Introduction

The results of the Census of Antarctic Marine Life (CAML) program have highlighted that a taxonomic inventory of the shelf benthic fauna in the Southern Ocean is still far from complete (De Broyer et al 2011; Griffiths et al 2011, 2014) and that the knowledge on the diversity of benthic communities below shelf depth is especially scarce (e.g., Hilbig 2004; Blake and Narayanswamy 2004; Brandt et al 2007; Kaiser et al 2007, 2011; Post et al 2011; Griffiths et al 2014). The Southern Ocean deep sea may provide an early warning system for understanding the effect of global warning on resident marine fauna (Kaiser and Barnes 2008). Studies on biodiversity, especially in the scarcely sampled deep sea (Griffiths 2010), are vitally important and will contribute to the evaluation of the current Southern Ocean fauna, and allow us to assess the degree of connectivity between its major basins, as well as vulnerability to future environmental changes

Methods

Results

Conclusion