Distributional records of sea cucumbers (Echinodermata, Holothuroidea) based on the collection stored at the Italian National Antarctic Museum (MNA, section of Genoa)

Study Extent

This dataset describes the occurrence of Holothuroidea samples stored in the biological collection of the Italian National Antarctic Museum (MNA) – Genoa section, collected in the framework of ten Ross Sea PNRA and one AWI expedition in the Bransfield Strait and the South Shetland Islands (Antarctic Peninsula) between 1987 and 2017. The data here presented originate from 89 different sampling stations ranging between 18 and 743 meters of depth.

Sampling

The dataset provides information on sea cucumbers (Holothuroidea) specimens collected from 1987 to 2017 and now part of the permanent biological collection at the Italian National Antarctic Museum (MNA) – Genoa section. The 328 samples composing this Database have been collected in a wide range of scientific projects with variety of scientific objectives employing a variety of sapling gears covering a total time interval of 30 years, for this reason the data presented here does not allow to provide a quantitative dataset but rather an occurrence resource for Antarctic holothuroids. Sampling was performed on a total of 89 different sampling stations (Fig. 1) through the deployment of a variety of sampling gears, mainly dredges whose specifications were often not properly described in the expedition’s reports (Charcot dredge, Naturalist dredge and Triangular dredge) and Van Veen grabs of different volumes. Other sampling instruments include two towed horizontal nets, one called “Small Hamburg Plankton Net” (Hydrobios, https://www.hydrobios.de/en/), used during the PNRA XXVIII expedition (2012/2013) and composed by a 1 m2 metallic frame opening and a nylon net of 2 mm of mesh size, and another one called “Multiple Net Mid-Water Tucker Trawl” (Aquatic Research Instruments, http://www.aquaticresearch.com/multi-net_mid_water_trawl.htm) used during the PNRA XXIX expedition (2013/2014) made of three different 900 μm mesh size nylon nets, each one attached to a different metallic frame of 1 m2 opening, which are opened sequentially at different depths. The “Agassiz trawl” employed during the PNRA XIX expedition (2003/2004) was made up of a rigid rectangular steel frame with an opening of about 120 cm in width and 50 cm in height and a bag made of sturdy polyamide yarn net with 8 mm side mesh. A second “Agassiz trawl” with a 3 m2 opening was used during the AWI ANT-XXIX/3 Expedition (2013). Some samples were also opportunistically collected by long fishing lines, mid water trawls (that touched the bottom due to a failure of the winches), trammel nets, and other fishing nets that provided additional material to standard techniques and a Van Veen grab of 65 L volume. During the PNRA XXV expedition (2009/2010) a few samples were hand-collected by SCUBA diving operations conducted by Stefano Schiaparelli at a maximum depth of 26 meters. A few occurrences listed in the data originate from samples acquired using uncommon methodologies for collection benthic sea cucumbers (e.g. gill nets, trammel nets) and some referred as samples obtained as by-catch from failed deployments. Most of the specimens were collected from the Terra Nova Bay area near the "Mario Zucchelli'' station using small boats and zodiacs, while a smaller number was collected from the Ross Sea using the R/V "Italica". The samples belonging to the AWI ANT-XXIX/3 Expedition (2013) were collected by Alvaro Maria Chiara on board the "Polarstern" Research Vessel from the Bransfield Strait and the South Shetland Islands (Antarctic Peninsula). Once the material has been acquired by the MNA after sorting and shipment activities, all the specimens were classified to the lowest possible taxonomic resolution. The present dataset has been formatted in order to fulfill the Darwin Core standard protocol required by the OBIS scheme (http://www.iobis.org/manual/lifewatchqc/) and according to the SCAR-MarBIN Data Toolkit (available at http://www.scarmarbin.be/documents/SM-FATv1.zip). Vouchers are now preserved in 90% ethanol (~56% of the entire collection), frozen (~43.5%), or in formalin (~0.3%).

Quality Control

All records were validated. Coordinates were plotted on map to verify the actual geographical location. All scientific names were checked for typo and matched to the species information backbone of Worlds Register of Marine Species (http://marinespecies.org/) and LSID were assigned to each taxa as scientificNameID. Event dates are compliant to ISO 8601 standard. Specimens were identified at the lowest possible taxonomic resolution. The species were classified according to dichotomous keys and the available scientific literature. The classification is based on Miller et al. (2017) phylogenetic review that is currently accepted in the World Register of Marine Species database (WoRMS 2023).

Method steps

1. The data set provided in this publication is composed of occurrences originating from different expeditions and projects, the treatment and steps adopted to process each sample may differ depending on the expedition, the project and the personnel involved. However, in most cases, the samples were usually sorted in situ on the basis of morphological characteristics and stored directly in formalin or absolute ethanol, to be subsequently identified by researchers at the Italian National Antarctic Museum (MNA) – Genoa section after being acquired in the biological collection. The samples are now stored in absolute ethanol, fixed in formalin or at -20°C.
2. Most of the records have been identified by Stefano Schiaparelli and Alice Guzzi using original descriptions and taxonomic keys. Identification is made in most cases through scanning electron microscopic (SEM) analysis of the dermal ossicles of sea cucumbers. For ossicles extraction, small portions of tissue were taken from oral tentacles, body wall and tube feet (when available). Each portion was placed on a separate watch glass and covered with several drops of sodium hypochlorite solution (6-14% active chlorine) (liquid bleach). When the soft tissue was completely dissolved, the ossicles were cleaned with water, air dried, mounted on aluminum stubs, and coated with gold.
3. The identification of many specimens, corresponding to more than 47% of the entire dataset, was aided by the application of DNA barcoding analyses, including the amplification and sequencing of the cytochrome oxidase I (COI) region, in a collaboration with the Canadian Centre for DNA Barcoding (CCDB) and uploaded to the Barcode Of Life Data System (BOLD System). The results obtained in this context will be the subject of another publication.

Holothuroidea specimens were identified to lower possible taxonomic resolution.

1. Animalia
   rank: kingdom
2. Echinodermata
   rank: phylum
3. Holothuroidea
   rank: class
4. Apodida
   rank: order
5. Dendrochirotida
   rank: order
6. Synallactida
   rank: order
7. Chiridotidae
   rank: family
8. Cucumariidae
   rank: family
9. Paracucumidae
   rank: family
10. Psolidae
    rank: family
11. Synallactidae
    rank: family
12. Synaptidae
    rank: family
13. Ypsilothuriidae
    rank: family

The geographic extent of the dataset includes a large portion of the Ross Sea and different sampling stations located around the South Shetland Islands on the Antarctic Peninsula.