East Weddell Sea echinoids from the JR275 expedition

Study Extent

General spatial coverage: East Weddell Sea, Antarctica Coordinates: 60.6774°S and 77.359°S; 44.0133°W and 26.779°W Temporal coverage: February 12, 2012–March 4, 2012 Taxonomic coverage: all benthic taxa

Sampling

This dataset represents 48 AGT and 8 EBS deployments: consisting of a single deployment at the South Orkneys at 279m; 15 at depths of ~400m; four at ~500m; 21 at ~600m; two at ~700m and four deployments at each of ~1000m, ~1500m and ~2000m deep (Figure 1, Table 1).
The AGT had an inner mesh size of 1 cm and a mouth width of 2 m. The EBS consisted of an epi-(below) and a supra-(above) net. Each of these nets has a mesh size of 500μm and an opening of 100x33cm. The cod end of both nets is equipped with net-buckets containing a 300μm mesh window (Brenke 2005). The AGT and EBS were trawled for 10 minutes (depending on depth, seabed type and the condition of the animals in the initial trawl) on the sea bed at a 1 knot speed. Following Brenke (2005) since the EBS epi- and supra-nets are collecting the same fauna, these were pooled and treated as a single sample.

Quality Control

A species name was given to each specimen when it was possible. Identifications and taxonomic accuracies are based on David et al. (2005a, 2005b), Pierrat et al. (2012), and Saucède et al. (2014). When identification was inconclusive, e.g. for small specimens at very early stages of development, only family or genus names were assigned. These specimens were referred to as gen. sp. or genus name sp. respectively and might belong to one of the species listed in the dataset (Table 2). Specimens referred to as Abatus sp. 1 belong to none of the species listed in the dataset. The specimen referred to in the dataset as Amphipneustes aff. similis is very similar in morphology to A. similis but it presents distinctive morphological characters that are not diagnostic of the aforementioned species. While included in this dataset as Amphipneustes aff. similis it is likely that this will be described as a new species after further morphological and genetic analyses. This dataset presents species occurrences and species richness of the individual AGT and EBS deployments.

Method steps

1. - Agassiz trawl sampling in the Weddell Sea - Once on board, the samples were photographed as total catch and then hand‐sorted into groups varying from Phylum to species level collections. Representatives of many taxa were photographed in detail. The wet‐mass (biomass) of the different taxa was assessed by using calibrated scales (with accuracy and resolution of 0.001 kg). Samples were fixed in 96% undenatured and precooled (at -20°C) ethanol (Linse 2008) and kept for a minimum of 48 hours in a -20°C freezer, with rotation of containers to ensure full preservation of material. - Epibenthic sledge sampling in the Weddell Sea - Once on the deck, the content of the samplers from the first deployment was immediately fixed in 96% undenatured and precooled (at -20°C) ethanol and kept for a minimum of 48 hours in a -20°C freezer. - The taxonomic identification was performed in the British Antarctic Survey laboratory using a stereomicroscope.

The present dataset focuses on the class Echinoidea (Echinodermata). It includes six families, 15 genera, and 22 species:

1. Echinoidea
   common name: Sea Urchins rank: class

The study area of this dataset was set in the Eastern Weddell Sea and focused on sampling the continental shelf, upper slope and over-deepened shelf basins of the Filchner Trough region of the Weddell Sea. This dataset presents species occurrences and species richness of the individual trawls (Agassiz Trawl and Epibenthic Sledge deployments).