the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 24 Nov 2025
Community structures and Taphonomic controls on benthic foraminiferal community from an Antarctic Fjord (Edisto Inlet, Victoria Land)
Abstract. Benthic foraminiferal assemblages are key indicators for reconstructing past environmental conditions due to their ecological preference and preservation potential. This study investigates the hard-shelled benthic foraminifera of Edisto Inlet; an Antarctic fjord located on the Northern Victoria Land Coast (Ross Sea). The Inlet is characterized by a well-preserved Holocene laminated sedimentary sequence, providing an invaluable tool to reconstruct local and regional environmental changes. Living and fossil assemblages from the upper 5 cm of sediment were analysed across five sites along an inner-to-outer fjord transect to assess their ecological preferences and preservation patterns. Sites located on the inner fjord are characterized by high accumulation rates, low dry densities, fine grain sizes, and elevated content of organic carbon, indicative of high phytodetrital input and anoxic, reducing conditions probably derived by the burial of fresh organic matter. The surface sediments at these sites host low-diversity low-densities living assemblages but are abundant in dead specimens, suggesting substantial mortality events probably linked to post-sea-ice breakup, high organic matter flux to the bottom, and oxygen depletion associated with low current activity. Total assemblages are dominated by calcareous (Globocassidulina biora, G. subglobosa) and agglutinated (Paratrochammina bartrami, Portatrochammina antarctica) taxa, reflecting sluggish circulation along with a high input of fresh organic matter. A sharp decline in calcareous forms points to intense carbonate dissolution caused by the low redox potentional inside the sediment that develops during the year. In contrast, transitional and outer sites show more diverse and better-preserved assemblages, including Trifarina angulosa, Nodulina dentaliniformis, Reophax scorpiurus and Globocassidulina spp. among others, consistent with stronger bottom currents and more oxygenated conditions of the outer bay in respect to the inner fjord sites. The site located at the fjord mouth reveal distinct fossil faunas, likely shaped by ecological succession and/or dissolution, highlighting the high environmental variability of this setting. Resistant agglutinated species (Pseudobolivina antarctica, Paratrochammina bipolaris, Miliammina arenacea) dominate these areas, underscoring their potential value for paleoenvironmental reconstruction. Comparison with the succession of the palaeocommunity collected in a nearby marine sediment core (TR17-08) suggests recent improvements in bottom conditions and organic matter content, though key taxa have not recovered to Late Holocene (3600–1500 years BP) levels. These findings highlight the sensitivity of benthic foraminiferal communities to sea-ice dynamics, organic matter input, and hydrographic conditions in Antarctic fjord systems.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Journal article(s) based on this preprint
We examine benthic foraminiferal communities along an inner-to-outer transect in a fjord of Victoria Land. Community structure reflects organic matter flux, sedimentation rates, and circulation regimes. Inner sites show signs of stress, likely tied to oxygen depletion after sea-ice break up. Outer sites have higher densities, suggesting improved conditions. Comparison between paleocommunities and modern assemblages shows that communities are still recovering from late Holocene changes.
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-5204', R. Mark Leckie, 27 Dec 2025
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
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RC2: 'Comment on egusphere-2025-5204', R. Mark Leckie, 03 Jan 2026
An interesting and well written and well illustrated paper by Galli and co-authors who document the communities of benthic foraminifera recovered in 5 short cores from the Edisto Inlet, a fjord in Victoria Land, East Antarctica, along the western edge of the Ross Sea. The goal was to reconstruct the environmental conditions that shaped the structure of benthic foram communities as a baseline of current conditions in the fjord, as well as establishing a baseline to monitor potential future changes in the environment due to human activity. Two cores were collected in the inner fjord, one on the sill at the entrance to the fjord, and two cores from the outer fjord. The upper 5-cm of each of these 5 cores was analyzed for both living (stained with Rose Bengal) and dead specimens of benthic forams, every 1 cm. The authors present census data based on the >125-micron size fraction. They plot species occurrences as a function of grain size with depth in the sediments and they create an age-depth model using Pb210 dating to demonstrate differences in sediment accumulation rate from the outer to inner part of the fjord. They evaluated the relationship between a number of environmental variables including grain size (proxy for sediment source such as IRD, and depositional process, such as currents), magnetic susceptibility (proxy for sediment source), redox potential, Eh (proxy for oxygenation), and total organic carbon (proxy for foram food availability). The authors also did multivariate 2-dimension nMDS analysis, which I am not very familiar with.
The authors carefully consider and evaluate the importance of food supply and the freshness of the organic matter, as well as dissolved oxygen at the seafloor and within the sediments, and hydrodraulic energy (currents), which facilitates ventilation at the seafloor. The results were compared with a previously published, nearby longer piston core record (Galli et al. 2024) to provide a broader context of environmental changes back through the Holocene. This is such an important study for establishing the ecology of Ross Sea benthic foraminiferal communities and their taphonomic changes, which can be directly applied to interpreting the paleoecology, paleoenvironment, and depositional conditions of fossil assemblages. I was struck by the differences in the living foram densities (abundances) between the inner fjord and outer fjord, as well as relative proportions of infaunal and epifaunal species, and the proportions of calcareous vs. agglutinated taxa. Lots of interesting stuff to think about!
My only issue with the study is that the authors did not consider the possible importance of water masses on the benthic foram communities, such as High Salinity Shelf Water (HSSW), which is very cold and known to be corrosive to foraminiferal carbonate, and modified Circumpolar Deep Water (mCDW), which may advect biosiliceous material (diatoms) and organic matter into the fjord. I was also interested to learn more about the possible role of sedimentation rate on foram community structure or preservation of foram tests. In my opinion, a brief discussion about the possible influence of water masses and sediment accumulation rate differences on benthic foram community structure would be a valuable addition to this paper.
I suggest that with minor revision these suggestions could be addressed. I look forward to seeing this paper published.
I have provided an annotated file that includes suggested word changes or questions for the authors to consider during revision. Below are some specific suggestions or questions:
Lines 33-34: possible influence of corrosive High Salinity Shelf Water (HSSW) to account for the high proportion of agglutinated specimens, and likewise, might there be some influence of mCDW in the inner fjord?
Lines 65-66: There have been numerous other studies of the distribution of modern benthic forams across the Ross Sea continental shelf, not just in the troughs, including McKnight 1962; Kennett 1966, 1968; Pflum 1966; Fillon, 1974; Osterman and Kellogg, 1979; Melis and Salvi 2009. Please see Seidenstein et al. 2024 J. Micropalaeontology for citations.
Line 110, Table 1 caption: Maybe add something in the caption about the location of these 5 cores in the fjord.
Line 275, Figure 9 caption: Could the dissolution influence be related to the presence of High Salinity Shelf Water (HSSW), which is known to be very cold and corrosive to carbonate, while the abundance of fresh OM at the inner sites is due to seasonal productivity in the fjord, perhaps stimulated by meltwater, and/or could some of the fresh OM be transported into the fjord by mCDW? Paper by Castagno et al. 2017; J. Marine Systems, shows how mCDW intrudes the continental shelf above HSSW.
Line 281: I'm thinking that water masses may also play a role; HSSW causing dissolution, and perhaps mCDW brings diatoms and OM from the shelf edge; mCDW may not be the primary factor, but perhaps a contribution factor?
Line 291: Are the sediments of the inner fjord rich in diatoms, too? Typically, biosiliceous sediments are very corrosive to foram carbonate; we've documented this in the Pliocene (Seidenstein et al. 2024) and Miocene (Bombard et al. 2024) of the Ross Sea continental shelf.
Line 302: Presence of HSSW over the outer sites may not only provide active bottom water currents, but also waters that are corrosive to carbonate; perhaps HSSW is another contributing factor at times for both the inner and outer fjord sites. I suggest adding some mention of potential water mass influence(s).
Line 315: likely due to the high concentration of organic matter?
Lines 358-359: As written, this discussion of sea ice is not clear to me; i.e., how this might be affecting the assemblages.
Line 370: including due to the influence of HSSW?
Line 386: which station/site?
Line 394: site 170?
Line 433: M. arenacea has been shown to be associated with HSSW.
Line 444: How much might the sedimentation rate differences between the inner fjord sites (high sed rates but very low foram abundances) and the outer fjord sites (low sed rates and higher foram abundances) be influenced by sediment dilution, in the case of the inner fjord sites versus sediment winnowing in the case of the outer fjord sites. It would be helpful for the reader to speculate about the role of sedimentation rate on the assemblages.
Line 451: caused by sea-ice break up, high productivity, high flux of organic matter, and dissolution of some calcareous species of benthic forams?
Reviewed by R. Mark Leckie, Univ. of Massachusetts Amherst
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
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RC3: 'Comment on egusphere-2025-5204', Maria Pia Nardelli, 12 Jan 2026
I had the pleasure to review the manuscript titled “Community structures and taphonomic controls on benthic foraminiferal community from an Antarctic fjord (Edisto Inlet, Victoria Land), by Galli et al.
The authors present data on living and dead communities of benthic foraminifera from 5 stations along an inner-outer fjord transect. The living assemblages are analyzed through the filter of selected environmental data (OC, grain size, porosity, Eh), which makes the results very interesting for ecological interpretations of present-day faunal distribution in the fjord. The comparison with dead faunas from the same cores and, for part of the stations, the comparison of modern and fossil faunas adds a temporal perspective to the study which is also precious for this remote are poorly known area of the world.
The scientific questions and the aims of the paper are completely in agreement with the topics of the Journal, and the results are very interesting and certainly deserve to be published.
However, I have minor comments/suggestions I hope the authors will consider useful to improve the manuscript before publication.
My first concern is about the fact that the fauna is uniquely interpreted on the base of organic matter, oxygen and grainsize-deduced hydrodynamics (currents). There is no description, even theoretical if CTD data are not available, of the water masses distribution in the area, and the possible presence of (occasional? Seasonal? Permanent?) brines in the deep water of the fjord.
The dominance of agglutinated species in other polar fjords has previously been associated with corrosive bottom water masses induced by brine cascading after sea-ice production. This is not impossible that this type of mechanism also affects the area studied in this paper. A short description of the hydrology of the fjord should be addressed in the introduction and included in the interpretations of the discussion section. The high dissolution is evoked to explain the loss of calcareous species in the innermost stations 24 and 34, where densities of living foraminifera are very low and assemblages are dominated by agglutinated species. However, this seems to be attributed to the high inputs of organic carbon in this area more than to water masses properties. Can we exclude that brine-enriched water is at least seasonally present in the area? This would possibly also explain the difference in ratio observed in dead assemblages (where calcareous species are more abundant).
Another concern is the preservation of samples for organic matter analysis. If I well understand, the cores were stored at 4°C before subsampling once back in lab (in Europe) and analyses of organic carbon. If this is right, it should be clearly stated, and it would be interesting to have an idea of the delay between sampling and analysis. If it is conceivable that this is a huge effort to transport samples frozen from Antarctica and some choices have to be done, it is highly probable that the sample preservation at 4° C for several weeks or months does not allow to be highly confident about the organic carbon data, and this could have had a big influence on the final concentration, especially concerning the most labile fraction of Corg. I think that the relative comparison among the stations is still possible, but I would avoid overinterpreting this data, as they could have been affected by degradation processes.
Please be careful in interpreting density variations of foraminifera in dead or fossil faunas when comparing sites that have different sedimentation rates. High or low densities can reflect real variations in local densities but can also be biased by higher or lower sedimentation rates. This is also true for the planktic forams that are used as proxies for water column productivity in the manuscript. Please take this aspect into account in your interpretation.
Concerning the figures, I would suggest:
- to add ocean circulation on fig. 1
- to use the same color for a same species in figure 3 and 4
- if possible, to add a figure where nMDS for a same station is given for living and dead faunas (to visually see the discussed differences)
- add to figure 8 the number of points available for each period represented by a colored bar (n= XXX).
Minor corrections/suggestions:
Line 46: Please replace “aquatic” with “marine”
Line 50: you should cite the Trox model from Jorissen et al. 1995
Line 67: please add a comma after Inlet
Line 67: restate: and which could be a key site. Please also explain why this could be a key site
Lines 69: It is not clear in this sentence which record you are talking about. You should rephrase and explain that a core already published exists and will be used for comparison in this work
Line 70: for assessing? Or to assess?
Line 74: please rephrase something like: 1) to characterize benthic foraminiferal assemblages in relation with environmental parameters, 2) to contextualize the modern…by comparing recent communities (dead and living) with the succession of paleocommunities recorded by Galli et al. (2025)
Line 82: “tidal” glaciers? This information can be very important, for interpretation of continental supply from glaciers
Lines 99-100. Can you please add more details about ocean circulation in the fjord? Even just reporting the data from Battaglia et al. 2024. Any info about presence of brines?
Line 10: How much high sedimentation rates? Can you give a range?
Table 1 : I think the date for station 34 should be 2023 (not 2024)
Line 116: please add details about the timing between sampling and analysis for OM.
Line 127: the samples stored at 4° were freez-dried. Were they so frozen before? At which temperature?
Line 140: How did you store sediment for living forams before labeling with RB once in laboratory?
Line 151-153. The branched forams are always excluded from countings because of this problem, but they are normally included in biodiversity data as qualitative information. This should be the case here, also. They can be used as indicators of high hydrodynamics.
Line 180: this should be sites 24 and 178 instead.
Line 210 : a total of 1589 counted tests.
Lines 211 and 212: please add “station” before 170.
Fig. 3 and 4: please use the same colors for a same species.
Fig. 5 and text in general: please be clair and consistent with the terminology, in order to avoid confusion. You should have living (RB stained), dead (instead of fossil?) and paleo (or fossil?) faunas.
Fig. 7 I would appreciate an additional figure with dead and living superimposed models for a same station.
Line 251: Please add “still” after assemblage.
Line 260: Divided? (instead of dived)
Line 260: reported by Galli et al. (2025).
Line 261: with emphasis
Line 285-286: it seems that the sentence lacks a word (a very harsh what?)
Line 291: be careful about conclusions on the base of planktic test accumulation. There is possible bias due to varying sedimentation rates.
Line 293-94: outside the fjord… from the ones of the inner fjord.
Line 299: please replace “comprising” with “ranging”
Line 300: it is reasonable to hypothesize
Line 319: componentS
Lines 334-36: I would rather say that the results is a combination of mortality and taphonomy.
Line 362: I would add that more studies need to be done to fully understand the variability of deep and intermediate water masses (possibly linked to benthic ecology) in this area.
Lines 372: is that possible that OM is more efficiently remineralised compared to the inner fjord and less OC is therefore buried?
Line 413: typo. Whiel sould be while
Line 431: please add a s to “suggest”
Line 447: I would dput “but still …of the latter” in brackets
Line 449: assemblageS…reflect
Line 451: this site is also charactersied by higher sedimentation rates. This can also be a reason.
Line 464: is that possible that agglutinated species are also indicative of less OM availability?
Citation: https://doi.org/10.5194/egusphere-2025-5204-RC3 -
AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
-
AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-5204', R. Mark Leckie, 27 Dec 2025
Publisher’s note: the content of this comment was removed on 6 January 2026 since the comment was posted by mistake.
Citation: https://doi.org/10.5194/egusphere-2025-5204-RC1 -
AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
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RC2: 'Comment on egusphere-2025-5204', R. Mark Leckie, 03 Jan 2026
An interesting and well written and well illustrated paper by Galli and co-authors who document the communities of benthic foraminifera recovered in 5 short cores from the Edisto Inlet, a fjord in Victoria Land, East Antarctica, along the western edge of the Ross Sea. The goal was to reconstruct the environmental conditions that shaped the structure of benthic foram communities as a baseline of current conditions in the fjord, as well as establishing a baseline to monitor potential future changes in the environment due to human activity. Two cores were collected in the inner fjord, one on the sill at the entrance to the fjord, and two cores from the outer fjord. The upper 5-cm of each of these 5 cores was analyzed for both living (stained with Rose Bengal) and dead specimens of benthic forams, every 1 cm. The authors present census data based on the >125-micron size fraction. They plot species occurrences as a function of grain size with depth in the sediments and they create an age-depth model using Pb210 dating to demonstrate differences in sediment accumulation rate from the outer to inner part of the fjord. They evaluated the relationship between a number of environmental variables including grain size (proxy for sediment source such as IRD, and depositional process, such as currents), magnetic susceptibility (proxy for sediment source), redox potential, Eh (proxy for oxygenation), and total organic carbon (proxy for foram food availability). The authors also did multivariate 2-dimension nMDS analysis, which I am not very familiar with.
The authors carefully consider and evaluate the importance of food supply and the freshness of the organic matter, as well as dissolved oxygen at the seafloor and within the sediments, and hydrodraulic energy (currents), which facilitates ventilation at the seafloor. The results were compared with a previously published, nearby longer piston core record (Galli et al. 2024) to provide a broader context of environmental changes back through the Holocene. This is such an important study for establishing the ecology of Ross Sea benthic foraminiferal communities and their taphonomic changes, which can be directly applied to interpreting the paleoecology, paleoenvironment, and depositional conditions of fossil assemblages. I was struck by the differences in the living foram densities (abundances) between the inner fjord and outer fjord, as well as relative proportions of infaunal and epifaunal species, and the proportions of calcareous vs. agglutinated taxa. Lots of interesting stuff to think about!
My only issue with the study is that the authors did not consider the possible importance of water masses on the benthic foram communities, such as High Salinity Shelf Water (HSSW), which is very cold and known to be corrosive to foraminiferal carbonate, and modified Circumpolar Deep Water (mCDW), which may advect biosiliceous material (diatoms) and organic matter into the fjord. I was also interested to learn more about the possible role of sedimentation rate on foram community structure or preservation of foram tests. In my opinion, a brief discussion about the possible influence of water masses and sediment accumulation rate differences on benthic foram community structure would be a valuable addition to this paper.
I suggest that with minor revision these suggestions could be addressed. I look forward to seeing this paper published.
I have provided an annotated file that includes suggested word changes or questions for the authors to consider during revision. Below are some specific suggestions or questions:
Lines 33-34: possible influence of corrosive High Salinity Shelf Water (HSSW) to account for the high proportion of agglutinated specimens, and likewise, might there be some influence of mCDW in the inner fjord?
Lines 65-66: There have been numerous other studies of the distribution of modern benthic forams across the Ross Sea continental shelf, not just in the troughs, including McKnight 1962; Kennett 1966, 1968; Pflum 1966; Fillon, 1974; Osterman and Kellogg, 1979; Melis and Salvi 2009. Please see Seidenstein et al. 2024 J. Micropalaeontology for citations.
Line 110, Table 1 caption: Maybe add something in the caption about the location of these 5 cores in the fjord.
Line 275, Figure 9 caption: Could the dissolution influence be related to the presence of High Salinity Shelf Water (HSSW), which is known to be very cold and corrosive to carbonate, while the abundance of fresh OM at the inner sites is due to seasonal productivity in the fjord, perhaps stimulated by meltwater, and/or could some of the fresh OM be transported into the fjord by mCDW? Paper by Castagno et al. 2017; J. Marine Systems, shows how mCDW intrudes the continental shelf above HSSW.
Line 281: I'm thinking that water masses may also play a role; HSSW causing dissolution, and perhaps mCDW brings diatoms and OM from the shelf edge; mCDW may not be the primary factor, but perhaps a contribution factor?
Line 291: Are the sediments of the inner fjord rich in diatoms, too? Typically, biosiliceous sediments are very corrosive to foram carbonate; we've documented this in the Pliocene (Seidenstein et al. 2024) and Miocene (Bombard et al. 2024) of the Ross Sea continental shelf.
Line 302: Presence of HSSW over the outer sites may not only provide active bottom water currents, but also waters that are corrosive to carbonate; perhaps HSSW is another contributing factor at times for both the inner and outer fjord sites. I suggest adding some mention of potential water mass influence(s).
Line 315: likely due to the high concentration of organic matter?
Lines 358-359: As written, this discussion of sea ice is not clear to me; i.e., how this might be affecting the assemblages.
Line 370: including due to the influence of HSSW?
Line 386: which station/site?
Line 394: site 170?
Line 433: M. arenacea has been shown to be associated with HSSW.
Line 444: How much might the sedimentation rate differences between the inner fjord sites (high sed rates but very low foram abundances) and the outer fjord sites (low sed rates and higher foram abundances) be influenced by sediment dilution, in the case of the inner fjord sites versus sediment winnowing in the case of the outer fjord sites. It would be helpful for the reader to speculate about the role of sedimentation rate on the assemblages.
Line 451: caused by sea-ice break up, high productivity, high flux of organic matter, and dissolution of some calcareous species of benthic forams?
Reviewed by R. Mark Leckie, Univ. of Massachusetts Amherst
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
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AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
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RC3: 'Comment on egusphere-2025-5204', Maria Pia Nardelli, 12 Jan 2026
I had the pleasure to review the manuscript titled “Community structures and taphonomic controls on benthic foraminiferal community from an Antarctic fjord (Edisto Inlet, Victoria Land), by Galli et al.
The authors present data on living and dead communities of benthic foraminifera from 5 stations along an inner-outer fjord transect. The living assemblages are analyzed through the filter of selected environmental data (OC, grain size, porosity, Eh), which makes the results very interesting for ecological interpretations of present-day faunal distribution in the fjord. The comparison with dead faunas from the same cores and, for part of the stations, the comparison of modern and fossil faunas adds a temporal perspective to the study which is also precious for this remote are poorly known area of the world.
The scientific questions and the aims of the paper are completely in agreement with the topics of the Journal, and the results are very interesting and certainly deserve to be published.
However, I have minor comments/suggestions I hope the authors will consider useful to improve the manuscript before publication.
My first concern is about the fact that the fauna is uniquely interpreted on the base of organic matter, oxygen and grainsize-deduced hydrodynamics (currents). There is no description, even theoretical if CTD data are not available, of the water masses distribution in the area, and the possible presence of (occasional? Seasonal? Permanent?) brines in the deep water of the fjord.
The dominance of agglutinated species in other polar fjords has previously been associated with corrosive bottom water masses induced by brine cascading after sea-ice production. This is not impossible that this type of mechanism also affects the area studied in this paper. A short description of the hydrology of the fjord should be addressed in the introduction and included in the interpretations of the discussion section. The high dissolution is evoked to explain the loss of calcareous species in the innermost stations 24 and 34, where densities of living foraminifera are very low and assemblages are dominated by agglutinated species. However, this seems to be attributed to the high inputs of organic carbon in this area more than to water masses properties. Can we exclude that brine-enriched water is at least seasonally present in the area? This would possibly also explain the difference in ratio observed in dead assemblages (where calcareous species are more abundant).
Another concern is the preservation of samples for organic matter analysis. If I well understand, the cores were stored at 4°C before subsampling once back in lab (in Europe) and analyses of organic carbon. If this is right, it should be clearly stated, and it would be interesting to have an idea of the delay between sampling and analysis. If it is conceivable that this is a huge effort to transport samples frozen from Antarctica and some choices have to be done, it is highly probable that the sample preservation at 4° C for several weeks or months does not allow to be highly confident about the organic carbon data, and this could have had a big influence on the final concentration, especially concerning the most labile fraction of Corg. I think that the relative comparison among the stations is still possible, but I would avoid overinterpreting this data, as they could have been affected by degradation processes.
Please be careful in interpreting density variations of foraminifera in dead or fossil faunas when comparing sites that have different sedimentation rates. High or low densities can reflect real variations in local densities but can also be biased by higher or lower sedimentation rates. This is also true for the planktic forams that are used as proxies for water column productivity in the manuscript. Please take this aspect into account in your interpretation.
Concerning the figures, I would suggest:
- to add ocean circulation on fig. 1
- to use the same color for a same species in figure 3 and 4
- if possible, to add a figure where nMDS for a same station is given for living and dead faunas (to visually see the discussed differences)
- add to figure 8 the number of points available for each period represented by a colored bar (n= XXX).
Minor corrections/suggestions:
Line 46: Please replace “aquatic” with “marine”
Line 50: you should cite the Trox model from Jorissen et al. 1995
Line 67: please add a comma after Inlet
Line 67: restate: and which could be a key site. Please also explain why this could be a key site
Lines 69: It is not clear in this sentence which record you are talking about. You should rephrase and explain that a core already published exists and will be used for comparison in this work
Line 70: for assessing? Or to assess?
Line 74: please rephrase something like: 1) to characterize benthic foraminiferal assemblages in relation with environmental parameters, 2) to contextualize the modern…by comparing recent communities (dead and living) with the succession of paleocommunities recorded by Galli et al. (2025)
Line 82: “tidal” glaciers? This information can be very important, for interpretation of continental supply from glaciers
Lines 99-100. Can you please add more details about ocean circulation in the fjord? Even just reporting the data from Battaglia et al. 2024. Any info about presence of brines?
Line 10: How much high sedimentation rates? Can you give a range?
Table 1 : I think the date for station 34 should be 2023 (not 2024)
Line 116: please add details about the timing between sampling and analysis for OM.
Line 127: the samples stored at 4° were freez-dried. Were they so frozen before? At which temperature?
Line 140: How did you store sediment for living forams before labeling with RB once in laboratory?
Line 151-153. The branched forams are always excluded from countings because of this problem, but they are normally included in biodiversity data as qualitative information. This should be the case here, also. They can be used as indicators of high hydrodynamics.
Line 180: this should be sites 24 and 178 instead.
Line 210 : a total of 1589 counted tests.
Lines 211 and 212: please add “station” before 170.
Fig. 3 and 4: please use the same colors for a same species.
Fig. 5 and text in general: please be clair and consistent with the terminology, in order to avoid confusion. You should have living (RB stained), dead (instead of fossil?) and paleo (or fossil?) faunas.
Fig. 7 I would appreciate an additional figure with dead and living superimposed models for a same station.
Line 251: Please add “still” after assemblage.
Line 260: Divided? (instead of dived)
Line 260: reported by Galli et al. (2025).
Line 261: with emphasis
Line 285-286: it seems that the sentence lacks a word (a very harsh what?)
Line 291: be careful about conclusions on the base of planktic test accumulation. There is possible bias due to varying sedimentation rates.
Line 293-94: outside the fjord… from the ones of the inner fjord.
Line 299: please replace “comprising” with “ranging”
Line 300: it is reasonable to hypothesize
Line 319: componentS
Lines 334-36: I would rather say that the results is a combination of mortality and taphonomy.
Line 362: I would add that more studies need to be done to fully understand the variability of deep and intermediate water masses (possibly linked to benthic ecology) in this area.
Lines 372: is that possible that OM is more efficiently remineralised compared to the inner fjord and less OC is therefore buried?
Line 413: typo. Whiel sould be while
Line 431: please add a s to “suggest”
Line 447: I would dput “but still …of the latter” in brackets
Line 449: assemblageS…reflect
Line 451: this site is also charactersied by higher sedimentation rates. This can also be a reason.
Line 464: is that possible that agglutinated species are also indicative of less OM availability?
Citation: https://doi.org/10.5194/egusphere-2025-5204-RC3 -
AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
-
AC1: 'Author's response to Reviewer #1 and Reviewer #2', Giacomo Galli, 19 Jan 2026
Dear Editor and Reviewer,
First, we would like to thank both reviewers for acknowledging the novelty of our study, for showing interest and enthusiasm in our work, and for raising important questions and comments about our findings.
While we reserve the opportunity to correct additional grammatical errors and to respond more specifically to the questions highlighted by the reviewers in a subsequent interaction, we would like to address the most important concerns raised in their reports:
- The influence of water masses (mCDW, HSSW, and/or brine production) on the benthic foraminiferal communities
- The influence of different sedimentation regimes on abundances
Regarding the first point, a recent study by Caridi et al. (2026, in press; preprint at http://dx.doi.org/10.2139/ssrn.5624076) showed different CTD profiles, indicating that the presence of HSSW is confined to the outer part of the bay, while in the inner part a slightly warmer bottom water is present (a modified version of mCDW). Reviewer #2 proposes a compelling explanation for the agglutinated versus calcareous pattern, namely the presence of brine-enriched bottom water. However, the oceanographic data presented in Caridi et al. (2026, in press) show no evidence of such a process influencing community structures, at least at the time when the CTDs were deployed. Furthermore, the Eh values shown in Figure 2 highlight the presence of dissolution conditions regardless of the presence of HSSW. In addition, tidal forcing appears to be an important contributing factor in controlling the hydrographic regimes in this area. Furthermore, to provide a broader context for the modern environment, other cores retrieved in the area show an order-of-magnitude drop in sedimentation rates around 700 yrs BP (Galli et al., 2023; Tesi et al., 2020), with values similar to those reported in Table 1. This implies a more localized and less regionally controlled environment respect to the Late Holocene.
Hence, while different water masses offer a compelling explanation for the modern environmental and ecological settings, we believe that a more local and synergistic effect of organic matter, hydrodynamic regime, oxygen availability, and grain size has produced the community patterns shown in the manuscript. However, we agree with both reviewers that there is a lack of oceanographic context in the manuscript that could help elucidate these questions and aid the reader. We will therefore add information consistent with what is described above in Section 1.1 (Line 100), where we will briefly explain the results from Battaglia et al. (2024) and Caridi et al. (2026, in press).
The second main point of discussion concerns the presence of different sediment accumulation rates from the inner part of the fjord to the outer areas and their contribution to structuring the dead assemblage.
Reviewer #1 suggests that high sedimentation rates in the inner part of the bay could lead to dilution of the concentration of tests per gram of dry sediment, while in the outer bay the presence of strong hydrodynamics could result in sediment winnowing, thus concentrating the number of tests. Especially in the outer bay, a high bottom-current regime could reduce the fine sediment fraction, producing the observed discrepancy (as shown in Figure 5). We thank Reviewer #1 for this observation and agree that this process could represent a taphonomic factor enhancing the discrepancy between the inner and outer parts of the fjord. We will add this process as a possible contributing factor in Section 4.2.
Furthermore, Reviewer #2 suggests that planktonic foraminifera abundance could be biased by the same type of effect proposed by Reviewer #1. However, as reported in the raw counts presented in the supplementary material, outer-bay sediment cores show no planktic foraminifera except in the 0–1 cm interval, whereas the inner bay contains planktic foraminifera throughout the upper 5 cm (as also shown in Figure 2). While absolute values may be misleading, the relative disproportion between the inner and outer parts of the bay with respect to planktic foraminifera suggests the presence of different primary productivity regimes, rather than a bias arising solely from differences in sedimentation regime.
Another important concern raised by Reviewer #2 relates to the reliability of the organic carbon data. The samples were retrieved in March 2024, transported under controlled thermal conditions, and analyzed the following year (March 2025). Our organic carbon analysis focused on total organic carbon (TOC) rather than on the specific nature of the organic matter (fresh vs. labile). Therefore, since we adopted standard procedures to analyze the total organic carbon content (as explicitly described in Section 2.2), and since the target of our analysis was not bioavailable carbon, we believe that the time elapsed between collection and analysis did not have a substantial effect on the measurements.
We hope to have been exhaustive on this first concerns.
On behalf of all co-authors,
Giacomo Galli
Citation: https://doi.org/10.5194/egusphere-2025-5204-AC1
Peer review completion
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We examine benthic foraminiferal communities along an inner-to-outer transect in a fjord of Victoria Land. Community structure reflects organic matter flux, sedimentation rates, and circulation regimes. Inner sites show signs of stress, likely tied to oxygen depletion after sea-ice break up. Outer sites have higher densities, suggesting improved conditions. Comparison between paleocommunities and modern assemblages shows that communities are still recovering from late Holocene changes.
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Francesca Caridi
Patrizia Giordano
Caterina Morigi
Anna Sabbatini
Leonardo Langone
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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We examine benthic foraminiferal communities along an inner-to-outer transect in a fjord of Victoria Land. Community structure reflects organic matter flux, sedimentation rates, and circulation regimes. Inner sites show signs of stress, likely tied to oxygen depletion after sea-ice break up. Outer sites have higher densities, suggesting improved conditions. Comparison between paleocommunities and modern assemblages shows that communities are still recovering from late Holocene changes.
We examine benthic foraminiferal communities along an inner-to-outer transect in a fjord of...
Publisher’s note: the content of this comment was removed on 6 January 2026 since the comment was posted by mistake.