Creepy-Crawlies of the Arctic Deep Sea: Metazoan Meiobenthic Communities Along a Latitudinal and Bathymetric Transect in the Western Arctic Ocean

Description

Sampling was conducted during the HLY2202 cruise (September 4th to October 24th, 2022) aboard the US-American icebreaker USCGC Healy (see cruise report by Ashjian and Grebmeier, 2024). This data set examines four stations along a latitudinal and water-depth transect in the western Arctic Ocean. Latitudes range from 77°N to 90°N and water depth ranges from 1720 m to 4237 m depth. Deep-sea sediment samples were collected by a multiple corer (MUC). MUC cores were subsampled for meiofauna and an array of biogeochemical and physical environmental parameters: bacterial abundance and biomass, organic carbon (C-org), phospholipids (LIPID), chloroplastic pigment equivalents (CPE), and water content (%H2O). Subsampling was conducted by means of plastic syringes with cut-off ends. Depending on the parameters sampled, 1.2 cm (bacteria, organic carbon, chloroplastic pigment equivalents) and 2.0 cm (meiofauna, phospholipids, water content) diameter syringes were used to subsample the top 3 cm of sediment. Sediment samples were subsequently separated into 1 cm layers for analysis. Meiofaunal data is shown as densities (individuals per 10 cm2). Mean densities were calculated from three (pseudo-)replicates (two at station 21). Nematode biomass was calculated with the Andrássy (1956) formula: WW = (L*W2)/Cf, with: WW [µg] = wet weight L [µm] = nematode’s length W [µm] = nematode’s width at widest point Cf = conversion factor which equals 1.6 * 106. The dry weight of the nematodes was calculated by using the dry- to wet-weight ratio of 0.25. Bacteria were separated from the sediment by ultrasound and diluted to a concentration of 1:4000 with a 4% filtered-seawater/formaldehyde solution. Bacterial cells were counted by epifluorescence microscopy to determine the total bacterial number (TBN) (see Meyer-Reil, 1983). An eyepiece graticule was used to determine the biomass per cell (see Grossmann & Reichardt, 1991), which was estimated using a conversion factor of 3.0 x 10-13 g C µm-3 (Børsheim et al., 1990) Total organic carbon content (C-org) of the sediments was determined with an Eltra CS 800 elemental analyzer. The phospholipid concentration was measured colorimetrically following a chloroform-methanol extraction of the lipids from the sediment (Greiser & Faubel, 1988). Chloroplastic pigments were extracted from the sediment with 90% acetone by homogenization in a Precellys homogenizer and subsequently measured with a Turner Fluorometer (Thiel, 1978). Hydrochloric acid (HCl) was used to differentiate between chlorophyll (CHLA) and its degraded products, phaeopigments (PHAEO). Water content (% H2O) was determined by measuring the difference in weight of wet sediment samples and sediment samples dried at 70°C.

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