the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Approaching the diversity and density dilemma of the lebensspuren-tracemaker tandem: a study case from abyssal Northwest Pacific
Olmo Miguez-Salas
Angelika Brandt
Henry Knauber
Torben Riehl
Abstract. In the deep-sea, the interaction between benthic fauna and substrate mainly occurs through bioturbational processes which can be preserved as traces (i.e., lebensspuren). Lebensspuren are common features of deep seafloor landscapes and usually more abundant than the organism that produce them (i.e., tracemakers), rendering them promising proxies to infer biodiversity. The density and diversity relationships between lebensspuren and benthic fauna are to the present day unclear and contradicting hypotheses have been proposed suggesting negative, positive, or even null correlations. To test these hypotheses, in this study lebensspuren, tracemakers (specific epibenthic fauna that produce these traces), degrading fauna (benthic fauna that can erase lebensspuren), and fauna in general were characterized taxonomically at eight deep-sea stations in the Kuril Kamchatka Trench area. No general correlation (over-all study area) could be observed between diversities of lebensspuren, tracemakers, degrading fauna and fauna. However, a diversity correlation was observed between specific stations, showing both negative and positive correlations depending on: 1) the number of unknown tracemakers (especially significant for dwelling lebensspuren); and 2) the lebensspuren with multiple origins; and 3) tracemakers that can produce different lebensspuren. Lebensspuren and faunal density were not correlated. However, lebensspuren density was either positively or negatively correlated with tracemaker densities, depending on the lebensspuren morphotypes. A positive correlation was observed for resting lebensspuren (e.g., ophiuroid impressions, Actinaria circular impressions), while negative correlations were observed for locomotion-feeding lebensspuren (e.g., echinoid trails). In conclusion, lebensspuren diversity may be a good proxy for tracemaker biodiversity when the lebensspuren-tracemaker tandem can be reliable characterized; and lebensspuren-density correlations vary depending the specific lebensspuren residence time, tracemaker density and associated behaviour (rate of movement), but on a global scale abiotic and other biotic factors may also play an important role.
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Olmo Miguez-Salas et al.
Status: open (extended)
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RC1: 'Comment on bg-2023-81', Rachel Przeslawski, 10 Jun 2023
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GENERAL COMMENTS
This study uses deep-sea imagery to investigate the relationships between lebensspuren (life traces on sediment) and various faunal groups, including those that make and those that degrade lebensspuren. The authors find high spatial variation and limited relationships between lebensspuren and faunal diversity and density. They relate their findings to previous similar studies in other deep-sea environments to try to understand broader patterns between lebensspuren and deep-sea diversity.
I find the ecological theory and introduction to this study a bit overstated and at times unclear. At its core, this study is a straightforward ecological analysis of lebensspuren and other biological and ecological variables. Its novelty is the differentiation of fauna into tracemakers and degrading fauna. The repeated emphasis on testing a ‘diversity and density hypothesis’ is vague and unclear. There are also odd phrasings used (‘diversity and density hypothesis’, ‘tracemaker-lebensspuren tandem’), and the use of ‘species’ is incorrect.
The discussion is well-written and goes into detail about the nuance and complexity of the ecology of lebensspuren in deep-sea environments.
The authors use an old lebensspuren classification system from 1954 when there is a more recent one that modern studies use (see Althaus et al 2015, Przeslawski et al 2012). It would be easier to relate the data and results here to previous studies if the authors used the same classification system as them. I suggest re-doing the classification and analyses (or at the very least, justifying why it was used and showing how it maps to the modern lebensspuren classification system).
SPECIFIC COMMENTS
The title is not readily understood most scientists, as the ‘diversity and density dilemma’ and ‘lebensspuren-tracemaker tandem’ are not common terms and border on jargon. Please rephrase to something more meaningful to a broader readership. E.g. ‘Relationships between lebensspuren and tracemaking organisms: a study case from the abyssal Northwest Pacific’
Line 18: change ‘bioturbational processes’ to ‘bioturbation’
Line 29: ‘between specific stations’ doesn’t make sense. Do you mean ‘at specific stations’?
Lines 37-42: There are too many statements in this last concluding sentence. Summarise more succinctly, or break into smaller sentences.
Line 45: change ‘as well as’ to ‘in relation to’. The study of animals and their substrates is not neoichnology; the study of traces of extant organisms is neoichnology.
Line 44 and elsewhere: ‘change ‘bioturbation processes’ to ‘bioturbation’.
Line 47: change wording. Lebensspuren are not ‘highly precise portraits’ of ecology. Their utility as proxies of biodiversity and ecological relationships remains uncertain and likely varies among ecosystems and species…as this study shows.
Line 65: This is incorrect - neither of these studies referred to lebensspuren morphotypes as species.
Lines 95-97: Variations in study findings does not necessarily mean a field is in its infancy. Other possibilities: Scale is too coarse to detect relationships in some systems and datasets- the nature of lebensspuren means that one is often operating a much coarser taxonomic resolution than organism identification. 2) ecological relationships vary across regions and ecosystems – not all abyssal environments are the same. You describe some of this well in your discussion.
Line 106: The ‘one step further’ is not clear here. The novelty of this study is the differentiation of marine fauna into ‘tracemakers’ which should be positively correlated to lebensspuren and ‘degrading fauna’ which should be negatively. The attempt to relate to broader ecological theory (e.g. ‘previous diversity and density hypotheses…’) is vague and confusing.
Line 151-155: Why did you use the 1954 classification system, and how does this map to the one used in much more recent lebensspuren studies (e.g. Bell et al, Przeslawski et al) and classification systems (e.g. CATAMI in Althaus et al 2015)?
Line 164-165, 172-173: Don’t do this. A ‘morphotype’ is not the same as ‘species’. Use ‘morphotype’ for lebensspuren and ‘morphospecies’ for fauna throughout. It is just as simple and is correct.
Line 214-216: What does this difference in standard deviation mean? That faunal diversity was more consistent among sites that the other diversity indices? Provide some context to these statements please.
Lines 217-218: ‘… with COMPARABLE DIVERSITY INDICES FROM the other three groups…’
Line 223: ‘Wasting lebensspuren’ isn’t great terminology since ‘wasting’ is an adjective that does not fit in this case – use ‘waste lebensspuren’
Line 229: reword ‘Lebensspuren assemblages were generally similar among station (Fig 5A).’
Line 234-241, Figure 2: Please use the same terms as previous studies for lebensspuren morphotypes – it looks like most of what you’re preferring to has already been classified in Przeslawski et al 2012.
Line 251: change ‘the obtained results’ to ‘results’
Line 252: What hypotheses or studies are you referring to? Recent studies suggest that they are indeed complicated relationships. This study supports this as well.
Line 284: I argue that unknown lebensspuren are an equal challenge – there are still some traces for which we have absolutely no idea what made them. See linear holes in Veccione et al 2022 (https://www.frontiersin.org/articles/10.3389/fmars.2022.812915/full) and spider trace in Przeslawski 2022 (https://www.frontiersin.org/articles/10.3389/fmars.2022.1086193/full)
Line 311: Has there been any attempt with automated image recognition for lebensspuren? I’d be keen to have a sentence or two discussing how AI may assist these kind of imagery analyses in the future.
Line 324-328: repetitive
Line 393-94: delete ‘it has to be kept in mind’ and other similar filler phrases throughout the ms
Lines 395-96: citation needed for these previous studies
Table 2: How does this relate to existing lebensspuren catalogue (Przeslawski et al 2012, Dundas and Przeslawski 2009)?
TECHNICAL COMMENTS
Line 412: reliably
Figure 4: subdivided
Citation: https://doi.org/10.5194/bg-2023-81-RC1 -
AC1: 'Reply on RC1', Olmo Miguez Salas, 12 Jul 2023
reply
We really appreciate your time and efforts to provide a detailed and quick review. We would like to thank the reviewer for their valuable and constructive comments that have been so helpful to improve the previous version of the manuscript. Here you can find a point by point response to all the raised comments.
The reviewers’ comments are in italics and our responses with regular typing to make it easier for you to check.
GENERAL COMMENTS
This study uses deep-sea imagery to investigate the relationships between lebensspuren (life traces on sediment) and various faunal groups, including those that make and those that degrade lebensspuren. The authors find high spatial variation and limited relationships between lebensspuren and faunal diversity and density. They relate their findings to previous similar studies in other deep-sea environments to try to understand broader patterns between lebensspuren and deep-sea diversity.
I find the ecological theory and introduction to this study a bit overstated and at times unclear. At its core, this study is a straightforward ecological analysis of lebensspuren and other biological and ecological variables. Its novelty is the differentiation of fauna into tracemakers and degrading fauna. The repeated emphasis on testing a ‘diversity and density hypothesis’ is vague and unclear. There are also odd phrasings used (‘diversity and density hypothesis’, ‘tracemaker-lebensspuren tandem’), and the use of ‘species’ is incorrect.
The reviewer is correct and the novelty of this study is to subdivide the fauna into tracemakers and degrading fauna for later diversity and density comparisons. We have modified the abstract and introduction (i.e., aims paragraph) to highlight this. Also, we added a last statement on the conclusions to highlight this.
The emphasis on “testing diversity and density hypothesis” is to inform the reader that different correlations have been observed previously between the fauna and lebensspuren (Kitchell et al., 1978, Young et al., 1985; Przeslawski et al., 2012). However, following your suggestion we have simplified the phrases and statements that expose these variable correlations.
We agree with the reviewer that tracemaker-lebensspuren tandem may confuse the reader. We have modified this.
The reviewer is correct on the use of “species”. None of these studies treated the Lebensspuren as a species, which is why we had put it in quotes. With the phrase we wanted to indicate that previous studies treated the lebensspuren morphotypes as "species" for statistical treatments (accumulation curves, diversity indices, etc). However, we think that the reviewer is right and the use of "species" is incorrect and can lead to confusion (see answer above for response to general comments). Therefore, we have modified the sentence. Also, we decided to use the term “taxon” (for the benthic fauna) instead as this is more generally valid, including morphologically discriminated species as well as higher levels of the systematic hierarchy, which in some cases had to suffice, e.g., due to poor image quality. The appropriate paragraph in the methods section has been adapted accordingly.
The discussion is well-written and goes into detail about the nuance and complexity of the ecology of lebensspuren in deep-sea environments. The authors use an old lebensspuren classification system from 1954 when there is a more recent one that modern studies use (see Althaus et al 2015, Przeslawski et al 2012). It would be easier to relate the data and results here to previous studies if the authors used the same classification system as them. I suggest re-doing the classification and analyses (or at the very least, justifying why it was used and showing how it maps to the modern lebensspuren classification system).
The classification we used is based on the two most relevant pillars of ichnology and have been adapted so they can usefully be applied to the data source we studied – still images. These pillars are: 1) behaviour (simplified Seilacherian categories; i.e., adapted to be applied to still images) and 2) morphology (morphology as the main ichnotaxobase; Bertling et al., 2022). However, being well aware of the published classification schemes the reviewer mentioned in regard to morphological names (Dundas and Przeslawski 2009, Przeslawski et al 2012, Althaus et al 2015) and to avoid unnecessary confusion and problems the same morphotype names have been applied – in most cases- in our study where possible without creating synonyms are ambiguous categories. Thus, our classification takes into account the state-of-the-art and widely accepted classification schemes that and, hence, we think that re-doing the classification is not necessary nor the analyses. Moreover, the diversity and density data will not vary due to just changing the names of the lebensspuren morphotypes. For more detail the classification we used is explained as follows:
The first one is related with the inferred tracemaker behaviour. In his pioneering paper Seilacher (1954) described the following behaviour in relation with lebensspuren: i. Resting lebensspuren—imprints of stationary animals. ii. Crawling lebensspuren—displaced sediment by movement of deposit feeders, sometimes marked by depressions left by the limbs. iii. Feeding structures—faecal casts and pellets. iv. Grazing lebensspuren—minor/fragile disturbances to sediment surface. v. Dwellings—mounds and burrows. However, these categories are rather difficult to assess from still images (e.g., differentiating between crawling and grazing or feeding vs. grazing). For example, in Althaus et al (2015) trails are assigned to crawling. The original crawling definition (Seilacher, 1954; Frey, 1973): trackways and trails (epistratal or intrastratal) made by animals traveling from one place to another. We know that some of these trails are carried out by echinoid that not only travel but also feed at the same time (e.g., Miguez-Salas et al., 2022). Thus, a crawling assignation to trails is not the most appropriate one.
The behavioural classification here is part of a neoichnotaxonomical manuscript that we submitted to another journal in collaboration with many ichnotaxonomical colleagues which differentiates 5 behaviours that can be identified in still images: Resting (cubichnia), Locomotion (repichnia), Dwelling (domichnia), Feeding (fodinichnia), and Wasting (digestichnia). Finally, with respect to this manuscript and the articles cited by the reviewer (Dundas and Przeslawski 2009, Przeslawski et al 2012, Althaus et al 2015), these papers use the waste cast category for faecal cast which are the most abundant lebensspuren in our study. However, the “waste cast” category is not a behavioural category in ichnological research. Even though it is not original seilacherian ethological category, wasting (digestichnia) is the proper name for this behavioural category which in general terms refers to “Wasting traces are formed as the organism excretes sediment particles from which organic material has been absorbed” (see Vallon et al., 2015 “An updated classification of animal behaviour preserved in substrates”; Bertling et al., 2022 “Names for trace fossils 2.0: theory and practice in ichnotaxonomy”).
The second one relates to the lebensspuren morphology. For this classification in fact we have tried to keep, as much as possible, the names proposed in Dundas and Przeslawski 2009, Przeslawski et al 2012, Althaus et al 2015. We have added some sentences in the methodology to highlight this. In fact, in the case of the wasting, resting and dwelling lebensspuren, most of the names are the same, following the proposals in the mentioned papers. We only modified the locomotion-feeding lebensspuren names because previously published names are rather simplistic (thick or thin trail) and do not offer any information about the lebensspuren seafloor epirelief. Since Frey (1973) wrote “Concepts in the study of biogenic sedimentary structures” until the recent ichnotaxonomical review of Bertling et al. (2022), one statement has remained, the morphology of the trace should be the corner stone and the main ichnotaxobase. Taking this into consideration, when describing a biogenic trace, the relief (see Fig. 4 in Frey 1973) is a basic morphological feature. That is why we have preferred to add flat or M-trail (when you have parallel sediment ridges in the margins) in order to give further detail in trail classification (rather than just saying thick or thin). This is also that we also discuss in the submitted neoichnotaxonomical manuscript.
SPECIFIC COMMENTS
The title is not readily understood most scientists, as the ‘diversity and density dilemma’ and ‘lebensspuren-tracemaker tandem’ are not common terms and border on jargon. Please rephrase to something more meaningful to a broader readership. E.g. ‘Relationships between lebensspuren and tracemaking organisms: a study case from the abyssal Northwest Pacific’
We agree with the reviewer; the title is perhaps too technical for a more general audience. Therefore we have modified it following her suggestion.
Line 18: change ‘bioturbational processes’ to ‘bioturbation’
Done
Line 29: ‘between specific stations’ doesn’t make sense. Do you mean ‘at specific stations’?
The reviewer is right. We have modified it.
Lines 37-42: There are too many statements in this last concluding sentence. Summarise more succinctly, or break into smaller sentences.
We have separated the statements.
Line 45: change ‘as well as’ to ‘in relation to’. The study of animals and their substrates is not neoichnology; the study of traces of extant organisms is neoichnology.
The reviewer is right. We have restructured the sentence.
Line 44 and elsewhere: ‘change ‘bioturbation processes’ to ‘bioturbation’.
Done
Line 47: change wording. Lebensspuren are not ‘highly precise portraits’ of ecology. Their utility as proxies of biodiversity and ecological relationships remains uncertain and likely varies among ecosystems and species…as this study shows.
We have removed the term "highly precise" to not overstate the sentence
Line 65: This is incorrect - neither of these studies referred to lebensspuren morphotypes as species.
The reviewer is correct. See above response.
Lines 95-97: Variations in study findings does not necessarily mean a field is in its infancy. Other possibilities: Scale is too coarse to detect relationships in some systems and datasets- the nature of lebensspuren means that one is often operating a much coarser taxonomic resolution than organism identification. 2) ecological relationships vary across regions and ecosystems – not all abyssal environments are the same. You describe some of this well in your discussion.
The reviewer is right - variability does not mean that a field is in its infancy. We modified that to just expose that there are few detailed lebensspuren studies to emphasize that it is a field that needs further exploration.
Line 106: The ‘one step further’ is not clear here. The novelty of this study is the differentiation of marine fauna into ‘tracemakers’ which should be positively correlated to lebensspuren and ‘degrading fauna’ which should be negatively. The attempt to relate to broader ecological theory (e.g. ‘previous diversity and density hypotheses…’) is vague and confusing.
We have modified the objectives and how the explanation on how this study goes “one step further”.
Line 151-155: Why did you use the 1954 classification system, and how does this map to the one used in much more recent lebensspuren studies (e.g. Bell et al, Przeslawski et al) and classification systems (e.g. CATAMI in Althaus et al 2015)?
See above response.
Line 164-165, 172-173: Don’t do this. A ‘morphotype’ is not the same as ‘species’. Use ‘morphotype’ for lebensspuren and ‘morphospecies’ for fauna throughout. It is just as simple and is correct.
We have modified this throughout the manuscript. However, we decided to use the term “taxon” instead as this is more generally valid, including morphologically discriminated species as well as higher levels of the systematic hierarchy, which in some cases had to suffice, e.g., due to poor image quality. The appropriate paragraph in the methods section has been adapted accordingly.
Line 214-216: What does this difference in standard deviation mean? That faunal diversity was more consistent among sites that the other diversity indices? Provide some context to these statements please.
It means what the reviewer suggests. We have added this statement following her suggestion.
Lines 217-218: ‘… with COMPARABLE DIVERSITY INDICES FROM the other three groups…’
Rephrased
Line 223: ‘Wasting lebensspuren’ isn’t great terminology since ‘wasting’ is an adjective that does not fit in this case – use ‘waste lebensspuren’
Done
Line 229: reword ‘Lebensspuren assemblages were generally similar among station (Fig 5A).’
Done
Line 234-241, Figure 2: Please use the same terms as previous studies for lebensspuren morphotypes – it looks like most of what you’re preferring to has already been classified in Przeslawski et al 2012.
See above response about lebensspuren naming concerns. The reviewer is correct and in the manuscript we have tried to stick to previously proposed names as much as possible (obtained from: Dundas and Przeslawski, 2009; Przeslawski et al 2012; Althaus et al., 2015)
Line 251: change ‘the obtained results’ to ‘results’
Done
Line 252: What hypotheses or studies are you referring to? Recent studies suggest that they are indeed complicated relationships. This study supports this as well.
The reviewer is right. We added the references and modified the sentence.
Line 284: I argue that unknown lebensspuren are an equal challenge – there are still some traces for which we have absolutely no idea what made them. See linear holes in Veccione et al 2022 (https://www.frontiersin.org/articles/10.3389/fmars.2022.812915/full) and spider trace in Przeslawski 2022 (https://www.frontiersin.org/articles/10.3389/fmars.2022.1086193/full)
The reviewer is right. We modified the examples in the sentence. We recently publish a paper (Brand et al., 2023) in relation to Veccione et al., 2022’s mysterious sublinear burrows. We found "similar” lebensspuren and one possible tracemaker (which does not mean that the other linear burrows are produced by amphipods as well). But, we know that for many dwelling lebensspuren an unknown classification is the most plausible one…..ultimately affecting diversity comparisons (we accordingly modified Line 336).
Line 311: Has there been any attempt with automated image recognition for lebensspuren? I’d be keen to have a sentence or two discussing how AI may assist these kind of imagery analyses in the future.
Yes indeed. This is something I discussed with Jen Durden and colleagues as well as within the FathomNet framework. The use of AI is promising for benthic fauna recognition. However, in the case of lebensspuren the future is more discouraging for a simple reason: the colour of the lebensspuren is almost always the same as that of the seafloor (background colour) therefore the algorithms cannot differentiate them. I tried personally one algorithm that was recently published (https://github.com/dmair1989/imagegrains) to quantify dimensions of river grains in planar surfaces – with the idea of identifying faecal cast automatically - and the result was not good at all. Mainly because the lack of colour contrast. I added a sentence explaining this limitation.
Line 324-328: repetitive
We agree. We deleted the first sentences to avoid repetition.
Line 393-94: delete ‘it has to be kept in mind’ and other similar filler phrases throughout the ms
Done
Lines 395-96: citation needed for these previous studies
Done
Table 2: How does this relate to existing lebensspuren catalogue (Przeslawski et al 2012, Dundas and Przeslawski 2009)?
See above response for lebensspuren naming concerns.
TECHNICAL COMMENTS
Line 412: reliably
Modified
Figure 4: subdivided
Modified
Citation: https://doi.org/10.5194/bg-2023-81-AC1 -
RC2: 'Reply on AC1', Rachel Przeslawski, 14 Jul 2023
reply
Thanks to the authors for their detailed reply to my reivew. I'm satisfied that they addressed my concerns in their response and revision and would be happy to see this paper accepted for publication.
Citation: https://doi.org/10.5194/bg-2023-81-RC2
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RC2: 'Reply on AC1', Rachel Przeslawski, 14 Jul 2023
reply
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AC1: 'Reply on RC1', Olmo Miguez Salas, 12 Jul 2023
reply
Olmo Miguez-Salas et al.
Olmo Miguez-Salas et al.
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