The Southern Ocean Radiolarian (SO-RAD) dataset: a new compilation of modern radiolarian census data

Kelly-Anne Lawler,Xavier Crosta,Amy Leventer,Vikki Lowe,Matthieu Civel-Mazens,Giuseppe Cortese,Helen Bostock,Leanne K Armand,John Rogers

doi:10.5194/essd-13-5441-2021

Abstract

Abstract. Radiolarians (holoplanktonic protozoa) preserved in marine sediments are commonly used as palaeoclimate proxies for reconstructing past Southern Ocean environments. Generating reconstructions of past climate based on microfossil abundances, such as radiolarians, requires a spatially and environmentally comprehensive reference dataset of modern census counts. The Southern Ocean Radiolarian (SO-RAD) dataset includes census counts for 238 radiolarian taxa from 228 surface sediment samples located in the Atlantic, Indian, and southwest Pacific sectors of the Southern Ocean. This compilation is the largest radiolarian census dataset derived from surface sediment samples in the Southern Ocean. The SO-RAD dataset may be used as a reference dataset for palaeoceanographic reconstructions, or for studying modern radiolarian biogeography and species diversity. As well as describing the data collection and collation, we include recommendations and guidelines for cleaning and subsetting the data for users unfamiliar with the procedures typically used by the radiolarian community. The SO-RAD dataset is available to download from https://doi.org/10.1594/PANGAEA.929903 (Lawler et al., 2021).

Highlights

The Southern Ocean is an important part of the global climate system as a major hub of oceanic circulation and nutrient redistribution
Sites included in the Southern Ocean Radiolarian (SO-RAD) dataset are representative of a broad range of environmental conditions
The SO-RAD dataset includes sites representing a large range of nutrient concentrations: nitrate (0.1–31.4 μmol kg−1), phosphate (0.1–2.2 μmol kg−1), and silicate (0.6–89.3 μmol kg−1) (Figs. 2 and 3)

Summary

Introduction

The Southern Ocean is an important part of the global climate system as a major hub of oceanic circulation and nutrient redistribution. Future changes to its physical, chemical, and biological properties will have global climate implications. Palaeoceanographic reconstructions of the Southern Ocean reveal its response to past climate and how it might respond to future climate change. Plankton distribution and abundance are related to the oceanic conditions prevalent in the water masses where these organisms live. After death, their skeletons settle to the ocean floor, becoming part of the sedimentary record. In the Southern Ocean, two main siliceous microfossil groups, diatoms and radiolarians, have been used to determine past environmental conditions such as ocean temperature (Cortese and Abelmann, 2002; Esper and Gersonde, 2014b; Panitz et al, 2015) and sea-ice coverage (Bianchi and Gersonde, 2004; Crosta et al, 2004; Gersonde et al, 2005; Esper and Gersonde, 2014a; Ferry et al, 2015)

Methods

Results

Discussion

Conclusion