Foraminifer and Ostracod Occurrence in a Cool-Water Carbonate Factory of the Cape Adare (Ross Sea, Antarctica): A Key Lecture for the Climatic and Oceanographic Variations in the Last 30,000 Years

Round 1

Reviewer 1 Report

The work Foraminifers and ostracods occurrence in a cool-water 2 carbonate factory of the Cape Adare (Ross Sea, 3 Antarctica): a key lecture for the climatic and 4 oceanographic variations in the last 30.000 years by Melis and Salvi may be consider a follow up of Brambati et al. (1999; Brambati, A.; Fanzutti, G.P.; Finocchiaro, F.; Melis, R.; Pugliese, N.; Salvi, G.; Faranda, C. 1999. Some paleoecological remarks on the Ross Sea Shelf, Antarctica. In Ross Sea Ecology, ItaliAntartide Expeditions (1987); Faranda, F., Guglielmo, E. Ianora, A. Eds., Springer-Verlag, Berlin: 51-61) were the core ANTA91-09 was described, including quite a discussion on foraminiferal and ostracod record. In the reviewed work, the two authors provided new detailed age-model and much more detailed micropaleontological datasets, consequently discussed their findings in much more detail as in the work from 1999, so for this reason this work provides new and important findings.

The text is generally well written, however, I have found some major problems calling for major revision of the manuscript. My major concerns are:

1. Although the authors did mention the Brambati et al. (1999) publication in the method section, I am not sure if they correctly credited that old publication throughout the work, for example in figure caption for Fig. 3. The authors should look carefully throughout the manuscript to take care of it.
2. The age model. There is one date missing on Fig. 2, i.e. the rejected one. If they plot it on the graph, the three upper-most points will actually align along a straight line. This may suggest that in all three upper-most samples, that they dated, there may be an admixture of older foraminiferal shells due some sedimentological processes that took place during deposition of the top 1 m of the core. Another possibility could be that they actually have two overlapping section one on the top of another. These are the two additional options for interpretation of the age of investigated sediments that the authors should at least address in the discussion, and reject if they find convincing arguments. The best option would be adding more dates in the upper 1 m of the core, but I realize it may be difficult.

On the same matter, at the beginning of the results the authors stated “All obtained radiocarbon ages are consistent with their stratigraphic position and therefore the effect of reworking the sediments can be considered negligible.” And in the second “ Only one date, obtained in the upper part of the core (73-75 cm, Table 1), shows an age reversal, likely indicating a remix of reworked foraminifers.” (lines 173-176) The second sentence negates the first one.

3. Chapter 4.1. The authors discuss calcareous sedimentary facies based on their composition including macrofossils like bryozoan etc., however they did not provide methodology how they collected these information. There is descriptive text in the Results, but it would be also good to see even a semi-qualitative info or a core log including such information, possibly as a supplementary material.
4. Conclusions. As they are now, they provide an attempt to integrate discussion of microfossil assemblages in chapters 4.3 and 4.4 with some kind of paleoenvironmental reconstruction. This effort deserves a final chapter of the Discussion (4.5) in my opinion and should be definitely better developed. There should be a summary figure produced for this final part of Discussion, incorporating FAs and OAs data shown now on Fig. 6 with other important data from the core and other records added. All FAs and OAs can be combined on single graphs each, making room for other data relevant for this discussion. The authors are stating in line 545 presence of four phases recognized; each of these should be clearly identified and discussed in a single subchapter and marked on the new Fig. 6.

Minor comments:

Line 87. Add research goals accounting for #4 above.

Line 100. Delete “respectively”

Line 109. ½ meaning 1-2 or 0.5?

Fig. 3. Tailor Dome data, possibly move to new Fig. 6. Granulometry data possibly show on a single graph. … add credit?

Fig. 4 shows forams in % and Fig. 5 ostracods in 3 per gram. It would help to follow the same scheme for the two. The authors could do one in the paper and the other in supplementary materials. For me showing % along with total # per gram would do. If so, raw data or # per gram in Table S1 and Table S2.

Lines 274-281, species and genera lacking italics.

Table 3. A. polylyca should be in bold.

Line 433. Genera at the beginning of sentences should be spelled in full. Correct throughout the text.

Line 466. “10.8% of total variance explained” or “10.8% of total variance” not “variance of 10.8%” and correct for all other FAs and OAs.

Line 502 … ?

Line 503. Rephrase “it was possible to divide the core levels into different intervals characterized by the 503 predominance of a precise association (OA)”

Line 511. 4.4.2, same for lines 521 and 527

Appendix A is also supplementary material, right? And it would not hurt to show SEM images of the major foraminifera discussed.

Tables S1 and S2. Decimal points; 4.1 not 4,1. And it would be good to see the general indices for S2.

Author Response

Reviewer 1

The work Foraminifers and ostracods occurrence in a cool-water 2 carbonate factory of the Cape Adare (Ross Sea, 3 Antarctica): a key lecture for the climatic and 4 oceanographic variations in the last 30.000 years by Melis and Salvi may be consider a follow up of Brambati et al. (1999; Brambati, A.; Fanzutti, G.P.; Finocchiaro, F.; Melis, R.; Pugliese, N.; Salvi, G.; Faranda, C. 1999. Some paleoecological remarks on the Ross Sea Shelf, Antarctica. In Ross Sea Ecology, ItaliAntartide Expeditions (1987); Faranda, F., Guglielmo, E. Ianora, A. Eds., Springer-Verlag, Berlin: 51-61) were the core ANTA91-09 was described, including quite a discussion on foraminiferal and ostracod record. In the reviewed work, the two authors provided new detailed age-model and much more detailed micropaleontological datasets, consequently discussed their findings in much more detail as in the work from 1999, so for this reason this work provides new and important findings.

------------------------------------------

The text is generally well written, however, I have found some major problems calling for major revision of the manuscript. My major concerns are:

1. Although the authors did mention the Brambati et al. (1999) publication in the method section, I am not sure if they correctly credited that old publication throughout the work, for example in figure caption for Fig. 3. The authors should look carefully throughout the manuscript to take care of it.

In the first sampling of the core we performed the sampling of 4-5 cm thick levels, whose data were used in Brambati et al., 1999. Subsequently, with more experience, a new sampling of greater stratigraphic detail was carried out and using layers with a maximum thickness of 2 cm, also in consideration of the rather coarse grain size of the sediment. Therefore, with the exception of some surface layers (from the top to 25 cm bsl), all the other present new data. All the radiocarbon dates used for this paper are unedited.

1. The age model. There is one date missing on Fig. 2, i.e. the rejected one. If they plot it on the graph, the three upper-most points will actually align along a straight line. This may suggest that in all three upper-most samples, that they dated, there may be an admixture of older foraminiferal shells due some sedimentological processes that took place during deposition of the top 1 m of the core. Another possibility could be that they actually have two overlapping section one on the top of another. These are the two additional options for interpretation of the age of investigated sediments that the authors should at least address in the discussion, and reject if they find convincing arguments. The best option would be adding more dates in the upper 1 m of the core, but I realize it may be difficult.

On the same matter, at the beginning of the results the authors stated “All obtained radiocarbon ages are consistent with their stratigraphic position and therefore the effect of reworking the sediments can be considered negligible.” And in the second “ Only one date, obtained in the upper part of the core (73-75 cm, Table 1), shows an age reversal, likely indicating a remix of reworked foraminifers.” (lines 173-176) The second sentence negates the first one.

Age models in Antarctica troubled by a number of difficulties when using the acid insoluble organic matter of the sediments (AIOM) due to the effect of reworking with older organic matter and the ageing of this material, with a general overestimate the age of the glacial retreat (e.g. Andrews et al., 1999, Hillebrandt et al., 2009). But, also considering ¹⁴C dates obtained using well preserved calcareous foraminifers, the age reversals are very common in Antarctic sediments subjected to the influence of bottom currents, gravitational phenomena or seafloor disturbances by icebergs or ice-shelf keels (Domack et al., 1999 Licht and Andrews, 2002; Mosola and Anderson, 2006; Anderson et al. 2014, Hillenbrand et al., 2017, Prothro et al., 2018, 2020). All radiocarbon ages obtained for our study, except one, are consistent with their stratigraphic position. The only date showing an age reversal is obtained in the upper part of the core (73-75 cm, Table 1). Considering that in the interval where the reversed age level was found there is no evidence of sedimentary structures indicating slumping or gravitational phenomena and that the depth of the core position was too high for the average depth of influence of icebergs (Martin et al., 2010), it is believed to be rather a problem due to the mixing of foraminifers reworked by bottom currents. Taking into account that all the other ages are in stratigraphic order and that the age model appears to work properly with the data discussions, it has been decided to exclude the inverse data from the discussions.

1. Chapter 4.1. The authors discuss calcareous sedimentary facies based on their composition including macrofossils like bryozoan etc., however they did not provide methodology how they collected these information. There is descriptive text in the Results, but it would be also good to see even a semi-qualitative info or a core log including such information, possibly as a supplementary material.

A semi-quantitative table (Table S1) with an estimate of the main organisms found in the gravel fraction has been added to the supplementary. It was not considered useful to carry out such a survey in the fraction < 1 mm, because it is very enriched with fragments of the most fragile bryozoans, which would be overestimated. 

1. Conclusions. As they are now, they provide an attempt to integrate discussion of microfossil assemblages in chapters 4.3 and 4.4 with some kind of paleoenvironmental reconstruction. This effort deserves a final chapter of the Discussion (4.5) in my opinion and should be definitely better developed. There should be a summary figure produced for this final part of Discussion, incorporating FAs and OAs data shown now on Fig. 6 with other important data from the core and other records added. All FAs and OAs can be combined on single graphs each, making room for other data relevant for this discussion. The authors are stating in line 545 presence of four phases recognized; each of these should be clearly identified and discussed in a single subchapter and marked on the new Fig. 6.

The chapter of the conclusions was changed as a subchapter of the discussions (4.5 Paleoenvironmental reconstruction inferred by the microorganisms) and accompanied by the new Figure 6, which includes both the associations to foraminifera and ostracods, and a reconstruction of the two different phases (activity/dormant) of the carbonate factory. The subchapter 4.5 has been better developed, but we chose to not divide it in the time intervals, to maintain the fluency of argument. Some arguments concerning the most important climate events, such as MWPs, have not been discussed again in this sub-chapter, because they have already been addressed in sub-chapter 4.1 of the discussion. The new “Conclusion” chapter was reduced.  

Minor comments:

Line 87. Add research goals accounting for #4 above.

DONE

Line 100. Delete “respectively”

DONE

Line 109. ½ meaning 1-2 or 0.5?

It means 1-2 cm, replaced

Fig. 3. Tailor Dome data, possibly move to new Fig. 6.

We add also these data to the Figure 6

Granulometry data possibly show on a single graph. … add credit?

We prefer to maintain the figure complete with the others abiotic data, to have a general point of view.

Fig. 4 shows forams in % and Fig. 5 ostracods in 3 per gram. It would help to follow the same scheme for the two. The authors could do one in the paper and the other in supplementary materials. For me showing % along with total # per gram would do. If so, raw data or # per gram in Table S1 and Table S2.

We know that it can be difficult to use different scales for the two groups of organisms. For reasons of high numbers, it is better to use frequency percentages with the foraminifers, while it is commonly used to express data in density for the ostracods, as they are much less numerous than foraminifers. In the supplementary tables we have also included the absolute numbers of individuals/species for both groups.

Lines 274-281, species and genera lacking italics.

DONE

Table 3. A. polylyca should be in bold.

DONE

Line 433. Genera at the beginning of sentences should be spelled in full. Correct throughout the text.

DONE

Line 466. “10.8% of total variance explained” or “10.8% of total variance” not “variance of 10.8%” and correct for all other FAs and OAs.

We eliminated the % of variance, as suggested by the reviewer 2, since they are reported also in the tables 2 and 3.

Line 502 … ?

DONE

Line 503. Rephrase “it was possible to divide the core levels into different intervals characterized by the 503 predominance of a precise association (OA)” 

We changed this sentence

Line 511. 4.4.2, same for lines 521 and 527 

DONE

Appendix A is also supplementary material, right? And it would not hurt to show SEM images of the major foraminifera discussed.

We apologize a lot, but this is not possible due to technical problems, because at the University of Trieste we no longer have access to the electron microscope, however the foraminifera mentioned are very common in Antarctic environment and therefore we believe that the addition of foraminifers’ photographic plates should be unnecessary

Tables S1 and S2. Decimal points; 4.1 not 4,1. And it would be good to see the general indices for S2.

In the two sent tables there are no decimal numbers with a comma, but it may be that this depends on the user's excel setting. The tables have been corrected and the general indices were added for the ostracods.

Reviewer 2 Report

Foraminifers and ostracods occurrence in a cool-water carbonate factory of the Cape Adare (Ross Sea, Antarctica): a key lecture for the climatic and oceanographic variations in the last 30.000 years

Authors: Melis R. and Salvi G.

General remarks

This study concerns the detailed sedimentological, macro- and micropaleontological analysis of a core retrieved in the Ross Sea (Antarctica), with a special focus on foraminiferal and ostracod faunas. The manuscript is well written, the presented material is new and the work provides interesting insights on the dynamics of ice shelves as recorded by benthic assemblages.

Overall, the manuscript structure and contents do not show major problems, it is well organized and the quality of the English is appropriate. Minor issues are indicated in the following sections (“minor remarks”) and, in my opinion, can be easily fixed. My major suggestion concern the final figure. In fact, I think that the work would greatly benefit from the addition of paleoecological indications in Figure 6. Events connected to ice sheet advances/retreats, related terrigenous inputs, climatic or oceanographic variations reported in the discussion section 4.1, are difficult to follow throughout the discussion because the authors combine a well compiled multi-proxy record. I strongly recommend to add paleoecological interpretation to figure 6, that in this way will provide all the necessary information to the reader, who will better understand the environmental evolution evidenced by microfossil assemblages.

Considering my observations and the high quality of the work, I suggest a minor revision.

Minor remarks

Introduction

Lines 85-97: Authors provide a first statement about the aim of the work, followed by a description of the study area. This is ok, but I recommend to finish the paragraph with a closure remark about the application of these microfossil groups in the above mentioned setting as objective of the work. In the current form, the text seems abruptly interrupted at the end of the introduction.

Materials and Methods

Lines 108-127: Authors describe the sieving procedures adopted for ostracods, but not for foraminifers. In addition: did the authors soaked the sediment samples before the sieving operations? Please specify in the text.
Authors state that the >50 µm fraction for ostracod analyses is a standard measure. This is not strictly true, as most deep-sea studies use the >63 µm, >125 µm or >150 µm fraction (e.g. Yasuhara et al., 2007; Yasuhara et al., 2012; Fanget et al., 2013). They can specify that the sediment fraction >50 µm allows to retain “adults and late moult stage juveniles for most species” similarly to the size fraction >63 µm.
Authors do not report the threshold value for ostracod countings (20, 100 valves…?). Please specify and eventually discuss the paucity of the ostracod assemblages in relationship with other findings in Antarctica.

Line 156: ecotypes – please specify why did you grouped ecotypes and which criteria did you used.

Lines 160-161: “disregarding minor and single occurrence species”. What did authors mean with “minor species”? Authors should set a threshold value, as they did for benthic foraminifers.

Results

Line 263: Do the authors mean that the first five axes of the PCA explain the 86.6% of the total variance? In a PCA, the total explained variance is always 100%, but considering all the axes, which are n-1 (with n=n. of variables, i.e. species). The same for ostracods at line 287.

Line 282: Authors do not present the distribution/trends of the most abundant taxa, as they did for benthic foraminifers. Please add a brief description about it.

Discussion

Line 374: Rapid ice mass loss occurred between 14.5-14.0 and 11.6-10.2 ka BP according to (Golledge et al., 2014; Lowry et al., 2019). Authors record high terrigenous contribution at 13.5-14.7 and 10.2-8.5 ka BP; the first one chronologically overlaps the first ice loss and MWP1A, but the second input occurred at the end of the second ice mass loss phase and after the MWP-1B (11.5-11.1). How did author explain this delay?

Liness 411-422: The text seems truncated at the end of the paragraph. It would benefit from the addition of a short discussion about similarities/discrepancies with your data and eventually some paleoecological insights as you did for foraminifers

Conclusions

In the conclusions, authors state that low productivity conditions are indicated by foraminifers >21 ka BP, but ostracods indicate productive waters >26 ka BP. Authors should clarify this point.

Line 578: The ACR appears here for the first time. It would be better to mention it in the discussion.

Minor remarks

Line 10: from near cape Adar

Line 17: The Holocene sequence

Lines 65, 71: Victoria Land Basin and Cape Roberts are cited, but are not shown in any figure as they fall out of the area in Fig. 1. Please specify their location.

Line 81: authors use the abbreviation “GZWs” without specifying its meaning. Please write the complete form.

Line 100: respectively

Line 151: Authors specify for the first time that they would analyze (through a multivariate method) benthic foraminifers; please make it clear in the objectives.

Line 174: effect of reworking the sediments -> effect of sediment reworking

Line 181, caption of Figure 4: please change foraminifera -> foraminifers (stick to a single choice)

Lines 203-208: Please authors should remove the reference to Figure 3 in the description of parameters not included in the figure (i.e. TC, TN)

Line 214: Biogenic hash -> Biogenic ash

Line 247: Discorbis vilardeboanus -> D. vilardeboanus

Lines 242-248: Please use the full name of the genus if citing a taxon for the first time in the text (i.e. Globocassidulina subglobosa in line 242, Epistominella exigua in line 247, Sigmoilina umbonata in line 248).

Line 252: Please use the full name of the genus if mentioning a taxon after the dot (Trifarina earlandi). In the same line, please report the distribution interval of T. earlandi in years, in accordance with the y-axis scale of your graph and the following discussions

Lines 274-286: Please write genus and species names in italics

Lines 283-284: dividing the core’s levels into precise intervals with higher and lower values

Line 305: has allowed us to offer -> offered us

Lines 337-338: the biogenic material subsequently served as a rigid substrate for subsequent colonies of encrusting organisms

Line 357: The consistent occurrence of pelite (from 5.1 to 84.8%, with a mean value of 60.2 ± 15.5%) -> Values already mentioned in the results section, please avoid in the discussion; the same occurs in line 407 for planktonic foraminifers

Line 394: Discorbis vilardeboanus

Line 404: Sigmoilina umbonata

Line 409: toward the top core -> toward the top of the core

Lines 409-410: open marine conditions similar to the modern day conditions -> open marine conditions similar to nowadays

Line 427 – ongoing: please write taxa names in italics also in the sub-section titles (4.3.1, 4.3.2, etc.). Moreover, avoid the repetition of the % of variance, already mentioned in the results.

Figure 3: Please state in the caption the significance of the grey intervals crossing the CaCO₃, TOC, C/N and δ¹⁸O curves

Figure 5: I suppose that the upper x axis values refer to Total density and number of taxa (S), and the lower x axis to Shannon index values; please specify in the caption and possibly color the lower axis values in accordance with the color of H

Comments for author File: Comments.pdf

Author Response

Reviewer 2

Foraminifers and ostracods occurrence in a cool-water carbonate factory of the Cape Adare (Ross Sea, Antarctica): a key lecture for the climatic and oceanographic variations in the last 30.000 years

Authors: Melis R. and Salvi G.

General remarks

This study concerns the detailed sedimentological, macro- and micropaleontological analysis of a core retrieved in the Ross Sea (Antarctica), with a special focus on foraminiferal and ostracod faunas. The manuscript is well written, the presented material is new and the work provides interesting insights on the dynamics of ice shelves as recorded by benthic assemblages.

Overall, the manuscript structure and contents do not show major problems, it is well organized and the quality of the English is appropriate. Minor issues are indicated in the following sections (“minor remarks”) and, in my opinion, can be easily fixed. My major suggestion concern the final figure. In fact, I think that the work would greatly benefit from the addition of paleoecological indications in Figure 6. Events connected to ice sheet advances/retreats, related terrigenous inputs, climatic or oceanographic variations reported in the discussion section 4.1, are difficult to follow throughout the discussion because the authors combine a well compiled multi-proxy record. I strongly recommend to add paleoecological interpretation to figure 6, that in this way will provide all the necessary information to the reader, who will better understand the environmental evolution evidenced by microfossil assemblages.

Figure 6 has been modified by adding the most important proxies considered for the palaeoenvironmental reconstruction and adding a sketch to represent the carbonate factory phases.

Considering my observations and the high quality of the work, I suggest a minor revision.

Minor remarks

Introduction

Lines 85-97: Authors provide a first statement about the aim of the work, followed by a description of the study area. This is ok, but I recommend to finish the paragraph with a closure remark about the application of these microfossil groups in the above mentioned setting as objective of the work. In the current form, the text seems abruptly interrupted at the end of the introduction.

We agree with this observation and we have changed the structure of the sentence also adding the multivariate statistics into the aims of the paper.

Materials and Methods

Lines 108-127: Authors describe the sieving procedures adopted for ostracods, but not for foraminifers. In addition: did the authors soaked the sediment samples before the sieving operations? Please specify in the text.

The methodology for the sample preparation for studying the foraminifers has been added

Authors state that the >50 µm fraction for ostracod analyses is a standard measure. This is not strictly true, as most deep-sea studies use the >63 µm, >125 µm or >150 µm fraction (e.g. Yasuhara et al., 2007; Yasuhara et al., 2012; Fanget et al., 2013). They can specify that the sediment fraction >50 µm allows to retain “adults and late moult stage juveniles for most species” similarly to the size fraction >63 µm. Authors do not report the threshold value for ostracod countings (20, 100 valves…?). Please specify and eventually discuss the paucity of the ostracod assemblages in relationship with other findings in Antarctica.

We modified the sentences in the text so better explaining counting methodology

Line 156: ecotypes – please specify why did you grouped ecotypes and which criteria did you used.

Ecotypes is not the appropriate word, we changed in the text with: …. “also combining the species with similar paleoenvironmental significance (i.e. Cibicides spp. and the unilocular taxa)” …

Lines 160-161: “disregarding minor and single occurrence species”. What did authors mean with “minor species”? Authors should set a threshold value, as they did for benthic foraminifers.

We modified the sentences in the text adding a threshold value such as made for forams

Results

Line 263: Do the authors mean that the first five axes of the PCA explain the 86.6% of the total variance? In a PCA, the total explained variance is always 100%, but considering all the axes, which are n-1 (with n=n. of variables, i.e. species). The same for ostracods at line 287.

It was a mistake; we did the correction for both the microorganisms.

Line 282: Authors do not present the distribution/trends of the most abundant taxa, as they did for benthic foraminifers. Please add a brief description about it.

A brief description of the ostracods has been added

Discussion

Line 374: Rapid ice mass loss occurred between 14.5-14.0 and 11.6-10.2 ka BP according to (Golledge et al., 2014; Lowry et al., 2019). Authors record high terrigenous contribution at 13.5-14.7 and 10.2-8.5 ka BP; the first one chronologically overlaps the first ice loss and MWP1A, but the second input occurred at the end of the second ice mass loss phase and after the MWP-1B (11.5-11.1). How did author explain this delay?

Considering the presence of un erosive contact at the passage between the carbonate and terrigenous sediments at the top of the core (Figure 3), some of the sediments related to MWP-1B may have been removed and, in addition, considering the limited gap with the event mentioned (i.e. about 500 yrs), the age attributed to the increased contribution of terrigenous material at the top of the core may be due to the approximation of the age model (that is linear interpolation).

 Lines 411-422: The text seems truncated at the end of the paragraph. It would benefit from the addition of a short discussion about similarities/discrepancies with your data and eventually some paleoecological insights as you did for foraminifers

The comparison between the two group of taxa in terms of environmental and ecological significance in Antarctic areas is complex due to the current scarce knowledge about Ostracods from the bibliographical point of view. A lot of information in fact comes from studies carried out in circumpolar areas, as signaled in the text discussions chapter on paleoenvironmental and climatic reconstruction. The response of the two associations to the glacial evolution of the area is similar, thus ensuring the possibility of provide a possible reconstruction of the complex environmental and climatic evolution that affected this Ross Sea area during the late Pleistocene period.

Conclusions

In the conclusions, authors state that low productivity conditions are indicated by foraminifers >21 ka BP, but ostracods indicate productive waters >26 ka BP. Authors should clarify this point.

The chapter “Conclusion” was changed and included into the discussion as “4.5. Paleoenvironmental reconstruction inferred by the microorganisms”, as suggested by the reviewer 1. In this way, we better developed the discussion of these results, including the question of the low productivity. The new figure 6 was added to better exemplify the final discussions.

Line 578: The ACR appears here for the first time. It would be better to mention it in the discussion.

We included the Antarctic Cold Reversal into the chapter 4.5 for the first time, since in our opinion it was not necessary to mention it before.

Minor remarks

Line 10: from near cape Adar

done

Line 17: The Holocene sequence

done

Lines 65, 71: Victoria Land Basin and Cape Roberts are cited, but are not shown in any figure as they fall out of the area in Fig. 1. Please specify their location.

Victoria Land Basin is nowadays called Northern Drygalski Basin, it was added in the new Figure 1. Cape Robert position was better specified in the text.

Line 81: authors use the abbreviation “GZWs” without specifying its meaning. Please write the complete form.

done

Line 100: respectively

done

Line 151: Authors specify for the first time that they would analyze (through a multivariate method) benthic foraminifers; please make it clear in the objectives.

As previously suggested, the aims of the paper have been better written and the use of the multivariate statistics has been added.

Line 174: effect of reworking the sediments -> effect of sediment reworking

done

Line 181, caption of Figure 4: please change foraminifera -> foraminifers (stick to a single choice) done

Lines 203-208: Please authors should remove the reference to Figure 3 in the description of parameters not included in the figure (i.e. TC, TN)

done

Line 214: Biogenic hash -> Biogenic ash

done

Line 247: Discorbis vilardeboanus -> D. vilardeboanus

done

Lines 242-248: Please use the full name of the genus if citing a taxon for the first time in the text (i.e. Globocassidulina subglobosa in line 242, Epistominella exigua in line 247, Sigmoilina umbonata in line 248). 

done

Line 252: Please use the full name of the genus if mentioning a taxon after the dot (Trifarina earlandi). In the same line, please report the distribution interval of T. earlandi in years, in accordance with the y-axis scale of your graph and the following discussions.

done

Lines 274-286: Please write genus and species names in italics .

done

Lines 283-284: dividing the core’s levels into precise intervals with higher and lower values. done

Line 305: has allowed us to offer -> offered us.

done

Lines 337-338: the biogenic material subsequently served as a rigid substrate for subsequent colonies of encrusting organisms.

done

Line 357: The consistent occurrence of pelite (from 5.1 to 84.8%, with a mean value of 60.2 ± 15.5%) -> Values already mentioned in the results section, please avoid in the discussion; the same occurs in line 407 for planktonic foraminifers.

done

Line 394: Discorbis vilardeboanus        

done

Line 404: Sigmoilina umbonata  

done

Line 409: toward the top core -> toward the top of the core .

done

Lines 409-410: open marine conditions similar to the modern day conditions -> open marine conditions similar to nowadays. 

done

Line 427 – ongoing: please write taxa names in italics also in the sub-section titles (4.3.1, 4.3.2, etc.).

This has been done, but we are not sure if it is the correct style of the journal.

Moreover, avoid the repetition of the % of variance, already mentioned in the results.

done

Figure 3: Please state in the caption the significance of the grey intervals crossing the CaCO₃, TOC, C/N and δ¹⁸O curves.

done

Figure 5: I suppose that the upper x axis values refer to Total density and number of taxa (S), and the lower x axis to Shannon index values; please specify in the caption and possibly color the lower axis values in accordance with the color of H .

Yes, this is right, we reported in the caption this distinction and we changed the axis color.

Round 2

Reviewer 1 Report

A few minor improvements may still be done:

Line 137; none foraminifera are illustrated, rephrase the sentence

285; I suppose, what you mean is  “The five-PC model used in this study explains 86.5% of the total variance in the benthic foraminifer data set”

330; sample, not ample

491 – Fig. 6; I believe “high/low productivity” should be “strong/weak upwelling”

620; in the period “before” 22.0 ka, not “below”

661; “increased bottom water productivity” What do you mean: strong upwelling or HSSW / Antarctic Bottom Water production?

670; “The last phase (up to 11.0 ka B.P.)” should not be …(after 11.0 ka B.P.) or …(between 11.0 and 8 ka B.P.)?

681; “potential for identifying” – recording instead identifying

Lines 697-701; I am not sure if this is a good closing statement for the Conclusions. It should be more connected with the present study.

Table S1, delete first spreadsheet, the one in Italian.

Author Response

The point-by-point reponses are included in the file attached below

Author Response File: Author Response.docx