DOI: 10.5281/zenodo.17714016
title: Conversion factors for Greenland shelf benthos: Weight-to-weight and body size-to-weight relationships

description: File 1: Weight-to-Weight Conversion Factors Benthos.xlsx

Description file 1: This dataset provides weight-to-weight conversion factors between wet mass (WM) [g], dry mass (DM) [g], and ash-free dry mass (AFDM) [g] for 43 macro- and mega-benthic families. The dataset includes taxonomic information (Phylum, Family, Genus) for each benthic taxon. The conversion factors were derived by including the WM, DM, or AFDM of all samples collected per family. For each family, the column “N” indicates the total number of individuals used. Each conversion factor of a family includes 95 % confidence intervals and squared R values (R²). Conversion factors of families with significant Spearman rank correlation tests (p-value < 0.05) are shown in bold text. These data enable reliable conversion between different biomass measures and support ecological, biogeochemical, and biodiversity studies in benthic research.

File 2: Body size-to-weight Conversion factors Benthos.xlsx

Description file 2: This dataset provides weight-to-body size conversion factors between wet mass (WM) [g], dry mass (DM) [g], and ash-free dry mass (AFDM) [g] and body size morphometrics (Carapax length, body diameter, disk diameter, outer diameter (across disk & arms), body length) [mm] for 43 macro- and mega-benthic families. The dataset includes taxonomic information (Phylum, Family, Genus) for each benthic taxon. The conversion factors were derived by including the WM, DM, or AFDM and body size morphometrics of all samples collected per family. For each family, the column “N” indicates the total number of individuals used. Each conversion factor of a family includes 95 % confidence intervals and squared R values (R²). Conversion factors of families with significant Spearman rank correlation tests (p-value < 0.05) are shown in bold text. These data enable reliable conversion between different biomass and body size measures and support ecological, biogeochemical, and biodiversity studies in benthic research.

File 3: Weights and sizes of all benthic samples (raw data file).xlsxDescription file 3: Raw data of macro- and megabenthic samples used in the analyses. The table includes 492 samples, listing for each the sample and station number, collection coordinates (latitude and longitude), taxonomic identification (Phylum, Class, Order, Family, Genus, Species), measured morphometrics (Carapax length, body diameter, disk diameter, outer diameter (across disk & arms), body length), body size (Size) [mm], wet mass (WM) [g], dry mass (DM) [g], and ash-free dry mass (AFDM) [g].File 4: Conversion factors between biomasses (weight-to-weight).R

Description & Methods file 4: This script calculates mass-conversion factors for 43 benthic invertebrate families by deriving regression slopes between the three mass types: wet mass (WM) to dry mass (DM), wet mass to ash-free dry mass (AFDM), and dry mass to ash-free dry mass. Analyses were performed in R (version 2024.04.0+735) using the functions lm() and coef() from the stats package (R Core Team, 2022).File 5: Conversion factors between body-size and biomasses (body size-to-weight).R

Description & Methods file 5: This script calculates size-to-mass conversion factors for 43 benthic invertebrate families by determining regression slopes between body size (Size) and three mass types: wet mass (WM), dry mass (DM), and ash-free dry mass (AFDM). Analyses were performed in R (version 2024.04.0+735) using the functions lm() and coef() from the stats package.File 6: Levenes and Shapiro Wilk Test.R

Description & Methods file 6: This script evaluates whether the variables wet mass (WM), dry mass (DM), ash-free dry mass (AFDM), and body size (Size) meet the assumptions of parametric tests by testing for homogeneity of variances and normality. Homogeneity of variances across benthic families was assessed using Levene’s test (leveneTest()) from the car package. Normality of each variable was tested using the Shapiro–Wilk test (shapiro.test()) from the stats package. To improve interpretability and explore potential transformations, variables were log-transformed (log()), square root-transformed (sqrt()), cube root-transformed (^ (1/3)), and inverse-transformed (1 / (x + 1)), while Box–Cox transformations were applied using the boxcox() function from the MASS package to identify optimal power transformations. Analyses were performed in R (version 2024.04.0+735), with all tests applied separately to each variable and its transformed versions (R Core Team, 2022). Variables failing the assumptions (Levene’s p < 0.05 for unequal variances or Shapiro–Wilk p < 0.05 for non-normality) were flagged as violating parametric assumptions, guiding the subsequent use of non-parametric analyses (Spearman rank correlations) in downstream analyses.File 7: Spearman Ranks Correlation between biomass (body weight) and body size.R

Description & Methods:

This script performs Spearman rank correlation tests to assess the relationships between wet mass (WM), dry mass (DM), and ash-free dry mass (AFDM). Analyses were performed in R (version 2024.04.0+735) using the function core.test() and the method spearman from the stats package (R Core Team, 2022).File 8: Spearman Ranks Correlation between body weight and body weight.R

Description & Methods:

This script performs Spearman rank correlation tests to assess the relationships between body size (Size) and three mass types: wet mass (WM), dry mass (DM), and ash-free dry mass (AFDM). Analyses were performed in R (version 2024.04.0+735) using the function core.test() and the method spearman from the stats package (R Core Team, 2022).
description: Methods for file 1: Weight-to-Weight Conversion Factors Benthos.xlsx

Benthic macro- and mega-invertebrate samples were collected as part of a trawl-bycatch programme at the Greenland Institute of Natural Resources (GINR) from the 11th of July 2023 to the 2nd of August 2023 on the research vessel Tarajoq between SE Greenland and the Tasiilaq region (59-67° N and 27-41° W). Sampling took place at 63 stations, including the shelf edge and shelf slope, as well as glacial throughs and banks, spanning depths between 200 m and 580 m. At each station, a COSMOS bottom trawl (twin-body trawl) was deployed and towed for 15 minutes. Benthic samples collected in the trawl were identified morphologically to the lowest possible taxonomic level, updated via WoRMS (2025), and most were resolved to genus or family. Sampling aimed on prioritizing habitat-representative and VME-indicator taxa. For each taxon, we included a balanced variety of body sizes and morphologies and avoided targeting specific body sizes or inclusion of atypical morphologies, such as disproportionately large shells or spicules. Fragile habitat-dominating species (such as bryozoans, like Hornera lichenoides or the glass sponge, Asconema sp.), often obtained as fragments, were still included in sample collection, due to their significant presence or ecological significance across stations. The size and biomass of each fragment were measured and processed in the same way as for complete organisms, with conversion factors derived from the fragment measurements rather than from whole organisms. Shells or housings that are produced by taxa such as bivalve shells or echinoderm tests were included in their weight. In the laboratory, wet mass (WM) [g] was measured. Samples were then dried at 70 °C to constant dry mass (DM) [g] and ashed at 450 °C for 24 h to obtain ash-free dry mass (AFDM) [g]. Conversion factors between WM and DM, WM and AFDM, and DM and AFDM were calculated for each taxonomic family as the slope of the regression between each pair of body mass variables (in R version 2024.04.0+735, function lm() and coef() from the stats package)(R Core Team, 2022).Methods for file 2: Body size-to-weight Conversion factors Benthos.xlsx

Benthic macro- and mega-invertebrate samples were collected as part of a trawl-bycatch programme at the Greenland Institute of Natural Resources (GINR) from the 11th of July 2023 to the 2nd of August 2023 on the research vessel Tarajoq between SE Greenland and the Tasiilaq region (59-67° N and 27-41° W). Sampling took place at 63 stations, including the shelf edge and shelf slope, as well as glacial throughs and banks, spanning depths between 200 m and 580 m. At each station, a COSMOS bottom trawl (twin-body trawl) was deployed and towed for 15 minutes. Benthic samples collected in the trawl were identified morphologically to the lowest possible taxonomic level, updated via WoRMS (2025), and most were resolved to genus or family. Sampling aimed on prioritizing habitat-representative and VME-indicator taxa. For each taxon, we included a balanced variety of body sizes and morphologies and avoided targeting specific body sizes or inclusion of atypical morphologies, such as disproportionately large shells or spicules. Fragile habitat-dominating species (such as bryozoans, like Hornera lichenoides or the glass sponge, Asconema sp.), often obtained as fragments, were still included in sample collection, due to their significant presence or ecological significance across stations. The size and biomass of each fragment were measured and processed in the same way as for complete organisms, with conversion factors derived from the fragment measurements rather than from whole organisms. Shells or housings that are produced by taxa such as bivalve shells or echinoderm tests were included in their weight. In the laboratory, wet mass (WM) [g] was measured and the body size [mm] of the full individual or fragment was measured using species specific morphometric features (Carapax length, body diameter, disk diameter, outer diameter (across disk & arms), body length). Samples were then dried at 70 °C to constant dry mass (DM) [g] and ashed at 450 °C for 24 h to obtain ash-free dry mass (AFDM) [g]. Conversion factors between WM and body size, DM and body size, and AFDM and body size were calculated for each taxonomic family as the slope of the regression between each pair of variables (in R version 2024.04.0+735, function lm() and coef() from the stats package) (R Core Team, 2022).Methods file 3: Weights and sizes of all benthic samples (raw data file).xlsx

Benthic macro- and mega-invertebrate samples were collected as part of a trawl-bycatch programme at the Greenland Institute of Natural Resources (GINR) between 11 July and 2 August 2023. Sampling was conducted aboard the research vesselTarajoq along the southeast Greenland shelf and in the Tasiilaq region (59-67° N, 27-41° W). A total of 63 stations were sampled, covering the shelf edge, shelf slope, glacial troughs, and banks, at depths ranging from 200 to 580 m. At each station, a COSMOS bottom trawl (twin-body trawl) was deployed and towed for 15 minutes. Benthic organisms retained in the trawl were identified morphologically to the lowest possible taxonomic level, updated via WoRMS (2025), with most specimens resolved to genus or family. Sampling aimed to include habitat-representative and VME-indicator taxa. For each taxon, we ensured a balanced range of body sizes and morphologies and avoided selectively targeting specific sizes or atypical forms (e.g., disproportionately large shells or spicules). Fragile, habitat-dominating species, such as bryozoans (e.g., Hornera lichenoides) and glass sponges (e.g., Asconema sp.), were often obtained only as fragments; these were nevertheless included due to their ecological relevance and frequent occurrence across stations. The size and biomass of each fragment were measured and processed in the same way as complete organisms, with conversion factors derived accordingly. Shells or housings produced by taxa such as bivalves or echinoderms were retained and included in total weight measurements. In the laboratory, wet mass (WM, g) was recorded first. Samples were then dried at 70 °C to obtain constant dry mass (DM, g) and subsequently ashed at 450 °C for 24 hours to determine ash-free dry mass (AFDM, g).
description: Funding: 

This work was funded by the Government of Greenland's partnership with the European Commission (Green Growth Programme) and the Aage V. Jensen Charity Foundation. Nadescha Zwerschke was also supported by the EU Horizon-funded POMP Project (Grant No. 101136875). We also acknowledge support from the Erasmus+ Programme of the European Union through an internship scholarship (Erasmus+ Internship Grant) that enabled Johanna Behrisch’s participation in the fieldwork in Nuuk and on the RV Tarajoq.