Macrobenthic Assessment of the South Sandwich Islands Reveals a Biogeographically Distinct Polar Archipelago

Oliver T Hogg,Anna-Leena Downie,Rui P Vieira,Chris Darby

doi:10.3389/fmars.2021.650241

Oliver T Hogg, Anna-Leena Downie + Show 2 more

Open Access

https://doi.org/10.3389/fmars.2021.650241

Copy DOI

Abstract

The sub-Antarctic South Sandwich Islands forms part of one of the largest marine protected areas (MPAs) in the world. Whilst the neighbouring island of South Georgia is known to be a biodiversity hotspot, very little was known about the benthic biodiversity or biogeography of the South Sandwich Islands. Here we present findings from the first biophysical assessment of this polar archipelago. Using open-access datasets, alongside results from a recent UK Government-funder Blue Belt expedition to the region, we assess how the island’s biodiversity is structured spatially and taxonomically and how this is driven by environmental factors. The South Sandwich Islands are shown to be both biologically rich, and biogeographically distinct from their neighbouring provinces. A gradient forest approach was used to map the archipelago’s benthic habitats which, based on the functional composition of benthic fauna and environmental characterisation of the benthic environment, demonstrated a distinct biogeographical north-south divide. This faunal and environmental discontinuity between the South Sandwich Islands and the rest of the MPA and between the different islands of the archipelago itself, highlights the importance of the zoned protection across the South Georgia and South Sandwich Islands Marine Protected Area.

Highlights

The South Sandwich Islands (SSI) archipelago forms part of the Scotia Arc, a predominantly submarine ridge that extends from the Terra del Fuego region of South America to the Antarctic Peninsula (Figure 1)
Marine benthic biodiversity at SSI was rich across taxonomic levels and comparable to the neighbouring biodiversity hotspot of South Georgia in terms of richness in phyla (18), classes (45), and families (447)
Whist record counts dropped at depths greater than 1,000 m, there was a secondary peak in record counts between 2,000 and 3,500 m which accounted for 22.2% of records

Summary

Introduction

The South Sandwich Islands (SSI) archipelago forms part of the Scotia Arc, a predominantly submarine ridge that extends from the Terra del Fuego region of South America to the Antarctic Peninsula (Figure 1). The water surrounding the islands form part of the South Georgia and South Sandwich Islands Marine Protected Area (SGSSI MPA), covering over 1 million km and representing one of the largest MPAs in the world (Collins et al, 2012; Trathan et al, 2014). Both the SSI and neighbouring South Georgia are internationally important sites for higher predators, hosting some of the largest populations of seabirds and marine mammals on Earth (Convey et al, 1999; Murphy et al, 2007; Clarke et al, 2012; Trathan et al, 2014; Rogers et al, 2015).

Methods

Results

Discussion

Conclusion