DOI: 10.5285/58080f33-884c-4e13-a419-c00cf1bab6a6
title: Pan-Atlantic comparison of deep-water macrobenthos diversity collected by epibenthic sledge sampling and analysis of patterns and environmental drivers.

description: Epibenthic samples were collected during the following research expeditions: ANDEEP-SYSTCO II, BIOPEARL I, DIVA1-3, IceAGE1-3&RR, IceDIVA1,2, JR275 and Vema-TRANSIT (Brandt & Wuerzberg 2014, Linse 2006, DIVA cruise reports, Brix et al. 2014, Devey & Brix 2017 cruise report, Brix & Taylor 2022, 2023, Griffiths 2012, Rhiel et al. 2018). While EBS diversity data at high taxon level were published for ANDEEP_SYSTCO II, DIVA1-3 and Vema-TRANSIT (Brandt et al 2014, Kaiser et al. in review, Brandt et al 2018), unpublished diversity data for BIOPEARL I, IceAGE1-3&RR, IceDIVA1, 2 and JR275 came from sample databases at DZMB Senckenberg and British Antarctic Survey, and are published here for the first time. During all 13 expeditions EBS with an epibenthic and a suprabenthic netsampler following the sampler sizes and height defined by Brandt and Barthel (1995) and Brenke (2005) were used, enabling comparability of samples. This type of EBS was a suitable device for sampling small benthic fauna on and above the seabed, including macrofauna and small-sized megafauna. The EBS holds an epi-and a suprabenthic netsampler (Brenke, 2005). Each of these nets has an opening of 100x33 cm and net mesh size of 500 micrometers. The cod ends are equipped with net-buckets containing 300 micrometer mesh windows. On deployment 1.5 times cable length to water depth were laid out and then EBS was trawled with 1 kn for 10 minutes on the seabed at a 1 knot for deployments in 500 m to 1500 m. Once on the deck, the content of the samplers was immediately fixed in 96 percent undenaturated and pre-cooled (at -20 degrees Celsius) ethanol. Samples were stored in a -20 degrees Celsius freezer for at least 48 h to reduce degradation of DNA for subsequent genetic studies. During this time, samples were gently rolled every three to six hours. Ethanol was changed once for all sub-fractions. In the laboratory, samples were initially sorted under a stereomicroscope to higher taxonomic ranks, lowest were class level for this analysis. Live specimen numbers were counted for abundance data and thanatocoenosis were not taken into account. For comparison between stations abundance data were standardised to 1000 m2 trawled area. The haul distances were calculated based on equation (4) in Brenke (2005). For comparison between stations abundance data were standardised to 1000 m2 trawled area. In this study we included data for 41 higher taxa of the initially separated 50 taxa ranging from phyla to orders. We excluded Foraminifera, Bryozoa, and fish. Brachiopoda, Chaetognatha, Echiura, Hemichordata, Nematoda, Nemertea, Phoronida, Platyhelminthes, Porifera and Priapulida were not identified beyond phylum level. Annelida were separated into Polychaeta, Sipunculida, Oligochaeta and Hirudinea. The phylum Arthropoda was split into the subphylum Chelicerata and Crustacea, with the former comprising Pycnogonida and Acarina and the latter crustacean order levels. Chordata only consisted of Tunicates. Echinodermata and Mollusca were separated into classes. For the DIVA1 & 2 data sets, Cnidaria and Echinodermata were not further discriminated into classes. For the DIVA-1, IceAGE 1-3 and IceDIVA1,2 data sets, Aplacophora were not separated into Caudofoveata and Solenogastres. So, if corresponding data on class assignment were available, these were reported separately, but for all univariate and multivariate analyses, classes within Aplacophora, Cnidaria and Echinodermata were grouped. The environmental parameters for this study were provided by Bio-ORACLE (http://www.bio-oracle.org/; Tyberghein et al., 2012; Assis et al., 2018). Bio-ORACLE identifies average (mean) values for different physical and chemical variables over a 14-year time period through a combination of satellite and in-situ measurements (2000 - 2014; Assis et al., 2018), at a resolution of 5 arcmin. In this study, surface and benthic (maximum depth) values were used for the following variables: salinity (PSS), silicate (mol/m3), iron (mmol/m3; mol/m3), phosphate (mmol/ m3; mol/ m3), nitrate (mmol/ m3; mol/ m3), chlorophyll-a (mg/m3; mg/cm3) and primary production (g/m3/day). Additionally, benthic data for temperature (degrees Celsius) and current velocity (m/s) as well as surface data for calcite (mol/ m3) and dissolved oxygen (mol/ m3) were included. This dataset outlines each EBS event along with temporal and spatial data. Abundances are reported raw and standardised /1000m2. PRIMER v6.0 (Clarke and Gorley, 2005) was used to perform a suite of multivariate statistical analyses: Similarity Percentage (SIMPER), Analysis of Similarities (ANOSIM), Biota-Environment Stepwise Analysis (BioEnv BEST) and Principal Components Analysis (PCA) (Hong and Zhinan, 2003). Analyses use taxonomic classification at the phyla level and at the multitaxon level (highest taxonomic classification achievable for each sample). 2 SIMPER analyses were conducted using standardised abundances to assess the contribution of taxa (at the phyla and 'multitaxon' level) to similarity analyses. A Bray-Curtis similarity matrix was used, and 90 percent was the cut off for low contributions to similarity. They used depth and region as factors. Depth split into the following factors using bins: abyssal (4000m-6000m), hadal (6000m), shelf (200m), bathyal (1000-4000m) and slope (200-1000m). Region is split into Vema Fracture Zone, Puerto Rico Trench, South West Atlantic, South East Atlantic, Southern Ocean, North West Atlantic and North West Atlantic. ANOSIM was conducted using standardised abundances from EBS sample to test whether there was a significant difference between samples based on different factors. 4 ANOSIMs were carried out: one for each depth and region (splitting samples as for SIMPER) at the phyla and 'multitaxon' level. PCA analysis is used to understand the associations between community composition and environmental factors, using standardised abundances. 2 PCA analyses were performed: one including 21 environmental variables (all factors: depth (m), latitude (decimal degrees), longitude (decimal degrees), temperature - mean at max dept (degrees Celsius), chlorophyll-a - mean at max depth (mg/m^3), dissolved oxygen concentration - mean at max depth (mmol/m^3), dissolved iron concentration- mean at max depth (mol/m^3), nitrate - mean at max depth (mmol/m^3), phosphate - mean at max depth (mol/m^3), salinity - mean at max depth (PSS), silicate - mean at max depth (mmol/m^3), current velocity - mean at max depth (m/s) primary productivity - mean at max depth, chlorophyll - mean at surface (mg/cm^3), calacite - mean at surface (mol/cm^3), dissolved iron concentration - mean at surface (mol/m^3), nitrate - mean at surface (mol/m^3), phosphate - mean at surface (mol/m^3), primary productivity - mean at surface, salinity - mean at surface (PSS), silicate - mean at surface (mol/m^3)) and one including 11 environmental variables (main factors: depth (m), latitude (decimal degrees), longitude (decimal degrees), temperature - mean at max depth (degrees Celsius), chlorophyll-a - mean at max depth (mg/m^3), dissolved oxygen concentration - mean at max depth (mmol/m^3), dissolved iron concentration- mean at max depth (mmol/m^3), nitrate - mean at max depth (mmol/m^3), phosphate - mean at max depth (mmol/m^3), salinity - mean at max depth (PSS), silicate - mean at max depth (mmol/m^3), current velocity - mean at max depth (m/s) primary productivity - mean at max depth). BioEnv analysis were conducted to test which environmental variables (up to 5 variables) best explain patterns in abundances. Spearman rank correlation method was used. Euclidean distance was used for resemblance analysis. 2 analyses were performed: one at the phyla level and one at the 'multitaxon' level. The following environmental variables were included in the analyses: depth (m), latitude (decimal degrees), longitude (decimal degrees), temperature - mean at max depth (degrees Celsius), chlorophyll-a - mean at max depth (mg/cm^3), dissolved oxygen concentration - mean at max depth (mol/m^3), dissolved iron concentration- mean at max depth (mol/m^3), nitrate - mean at max depth (mol/m^3), phosphate - mean at max depth (mol/m^3), salinity - mean at max depth (PSS), silicate - mean at max depth (mol/m^3), current velocity - mean at max depth (m/s) primary productivity - mean at max depth, chlorophyll - mean at surface (mg/cm^3), calacite - mean at surface (mol/m^3), dissolved iron concentration - mean at surface (mol/m^3), nitrate - mean at surface (mol/m^3), phosphate - mean at surface (mol/m^3), primary productivity - mean at surface, salinity - mean at surface (PSS), silicate - mean at surface (mol/m^3).
description: Comparable deep-water benthos datasets collected by epibenthic sledges (EBS) with an epibenthic and a suprabenthic netsampler in the Atlantic Ocean have been gathered since 2006. They were collected during the international research expeditions: ANDEEP-SYSTCO II, BIOPEARL I, DIVA1-3, IceAGE1-3RR, IceDIVA1,2, JR275 and Vema-TRANSIT. While EBS diversity data at high taxon level were published for ANDEEP_SYSTCO II, DIVA1-3 and Vema-TRANSIT, unpublished diversity data for BIOPEARL I, IceAGE1-3RR, IceDIVA1, 2 and JR275 came from sample databases at DZMB Senckenberg and British Antarctic Survey, and are published here for the first time. In total, diversity data for 143 EBS deployments from 13 expeditions were available for analyses based on identification on 50 taxon levels, including phyla, subphyla, classes and orders. During all 13 expeditions EBS with an epibenthic and a suprabenthic netsampler following sampler sizes and height , enabling comparability of samples. This type of EBS was a suitable device for sampling small benthic fauna on and above the seabed, including macrofauna and small-sized megafauna. We analyse pan-Atlantic benthic data from a range (119m - 8338m) of depths. For the pan-Atlantic analyses we defined seven regions to pool EBS locations based on their position North and South of the Equator and to the mid-Atlantic Ridge (MAR): East and West of the MAR, the Vema Fracture Zone as a gap in the MAR, the Southern Ocean south of the MAR and the Puerto Rico Trench as a deep-sea trench. In this study we included data for 41 higher taxa of the initially separated 50 taxa ranging from phyla to orders. The environmental parameters for this study were provided by Bio-ORACLE, which identifies mean values for different physical and chemical variables over a 14 year time period through a combination of satellite and in-situ measurements (2000 - 2014), at a resolution of 5 arcmin. 4 multivariate analyses (PCA, ANOSIM, SIMPER and BioEnv BEST) were carried out on standardised abundances using PRIMER software. the results of which are presented in this dataset.