| 23 Jan 2026
Conversion factors for Greenland shelf benthos: Weight-to-weight and body size-to-weight relationships
Abstract. Climate change and biodiversity loss are rapidly transforming Arctic marine ecosystems. Benthic ecosystems on Arctic shelves are important for biodiversity and ecosystem functioning. Biomass in form of ash-free dry mass (AFDM) is often used as a proxy of ecosystem health but can be labour intensive and costly to obtain. This study addresses a key data gap by providing robust weight and body size to weight conversion factors for Arctic and boreal benthic fauna. We collected samples of common macro- and mega-benthic organisms in SE Greenland (59–67° N and 27–41° W) and calculated conversion factors for wet mass (WM) to dry mass (DM) (40 families) and to AFDM (39 families) and DM to AFDM (42 families) (https://doi.org/10.5281/zenodo.17714017) (Behrisch and Zwerschke, 2025). To improve sampling output from non-destructive image-based sampling we also calculated conversion factors between body size (length, diameter) and weight for a subset of families (Behrisch and Zwerschke, 2025). Our dataset includes several Vulnerable Marine Ecosystem (VME) indicator taxa for the Arctic region. The conversion factors for Atlantic-Arctic benthos presented here can serve as the foundation for a growing database, helping to unify datasets collected using different methodologies.
The manuscript provides needed data on biomass conversion factors for Arctic seafloor invertebrate fauna from a region undergoing rapid climate change. these data will be of interest to modellers and benthic ecologists, as well as academics that are interested in food web structure.
The data are straightforward and have been collated using appropriate methods that are well described, and are available from an open and accessible online archive. I have a few very minor suggestions the authors may wish to consider:
1. Abstract - the authors highlight climate change and biodiversity loss as transformative drivers of change, which is entirely correct, but do not include human activity which seems a little remiss as human exploitation of higher latitudes is accelerating. I would suggest including anthropogenic activity in this statement. this also holds true for the similar statements at the start of the Introduction. An example of emerging human impact would be Williams et al. 2024 (DOI: 10.1002/ece3.11702), but there will be others that could support such a statement.
2. Introduction, line 26: I take the point that these areas are not as well constrained as other locations, but the distribution of fauna across some areas of the Arctic are well documented in terms of species assemblage structure and, albeit to a lesser extent, ecosystem functioning (e.g. Jorgensen et al. 2015, doi: 10.1093/icesjms/fsu106; solan et al. 2020, doi: 10.1098/rsta.2019.0365). It would be good to highlight this disparity.
3. Introduction, line 27: the statement about different methodologies being adopted in the deep sea seems out of place and it is not clear what the authors are highlighting. This needs some clarification. Do you mean different ways of estimating biomass? why highlight only the deep sea, and what do you mean by deep (non-shelf?)?
4. Introduction, second and third paragraphs: this section would benefit from stating what will be achieved by having this database, and what these data are explicitly used for and, if appropriate, examples where the derived conclusions have had low confidence because of lack of data. At the moment, whilst correct, these paragraphs are not very compelling to the reader and would benefit from being strengthened.
5. the methods section is well written and largely comprehensive. It is, however, less clear on where (which stations?) and how many individuals individual estimates are based on. Some justification should be given, or limitations highlighted or at least explicitly stated, over how confident each estimate of biomass is. The number of individuals on which the biomass value is based varies, as does the location from which such individuals are pooled. For example, if individuals have been pooled across the entire sampling area, that is very different to if the samples were derived solely from the north or south, or from shallow vs deeper environments. Some cross reference to the environmental variability needs to be included alongside these estimates. Perhaps maps of the main groups could be provided simply highlighting the stations from which estimates were derived with a coloured symbol and the value of n from each station annotated next to the station. Such maps could be added to the supplementary information.
6. The morphometrics should be described in the text, or reference to a diagram or whatever is appropriate in the supplementary material to indicate what was measured. Were fauna anaethetised when they were measured, for example? What was the accuracy of the measurement, and were rulers or callipers or some other method used to obtain the measure?, and so on.
7. Section 2.3 - the description of the statistical analyses does not state what was deemed acceptable in terms of the number of values, and the regressions should be provided in graphical form (scatterplots) for the reader to see how good a fit they are to the data. The table should also include the R2 value, as well as the value of n, alongside the slope parameter (although i see that some are listed in the next section). i would also like to see some indication of confidence as an extra column, perhaps a simple red, amber, green traffic light system based on number of samples and level of fit criteria.
8. In the results section some wider statements would be interesting to the reader, such as what the range of the slopes were and which groups had the more or less of a slope. Are they consistent with similar groups derived elsewhere? are they within expectation? D they vary spatially, and if so, by how much? Provide some context to the results.
9. Line 163 (and elsewhere) - the authors refer to common names, which is fine for readability, but the scientific group names should be added in brackets so it is clear which group they are referring to as common names vary around the globe.
10. The conclusion states that the data open the door for estimating biomass from non-invasive methods (e.g. photographs), suggesting that this might be the motivation for the work, but this is not expanded in the introduction. Some reference to ethics and avoiding the use of animals should be referenced to support this point. some reference back to the main points stated in the introduction would round up the paper, particularly a statement of what now can be achieved or some suggestion as to what is now possible given these data.
I hope my comments will be useful to the authors.