the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 16 May 2023
Coccolithus pelagicus subsp. braarudii morphological plasticity in response to variations in the Canary region upwelling system over the past 250 ka
Abstract. Coccolith size matters on routine identification of calcareous nannofossil species. But morphometry can also be a tool to study their morphological plasticity and adaptations to environmental patterns. Most current studies are limited in extracting morphological plasticity data, with most statistical methods varying from histogram analysis to mixture analysis, or even multistatistical analysis, allowing the identification of morphotypes but with significant assumptions (e.g., normal distribution) on the morphological pattern of the potential different morphotypes within a population. To address this limitation a multivariate statistical morphometrical tool, Integrated Multivariate Morphon Analysis (IMMA), was developed to identify different placolith morphotypes regarding maximum coccolith length and applied to Quaternary GeoB5559-2 samples, using morphometry data of C. p. braarudii. The results show that IMMA and morphometry microvariations can be used to extract variations in upwelling intensity and primary productivity, extracting the morphological plasticity of C. p. braarudii as a response to primary productivity variations. Thus, IMMA has great potential for studies on the effects of climatic events on coastal upwelling regions during the Quaternary.
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RC1: 'Comment on cp-2023-31', Anonymous Referee #1, 20 Jun 2023
General Comments
The manuscript by Prista et al. presents a morphometric record of C. pelagicus, unprecedented in the Canary region for the last 250 kyr, focussed on the application of the Integrated Multivariate Morphon Analysis (IMMA) tool. From their results, the authors suggest the microvariations observed to be considered as response of morphological plasticity of C. p. braarudii to upwelling intensity and primary productivity conditions in the region, supporting the use of IMMA as a tool to track short-term climate effects on coccolith morphometry during the Quaternary.
The data in this study is of quality, great novelty and the contribution is valuable for the region of study. The topic in this research is also of general interest and of important potential use, either for the nannoplankton community or for scientists interested in paleoclimatic/paleoceanographic reconstructions. Thus, the manuscript represents a contribution which is clearly within the scope of CP. However, some of the determinations in this study are not yet entirely supported, at least in the current state in which the data is presented and discussed, giving rise to a scientific quality of the manuscript that could be improved.
The manuscript emphasizes the ability of IMMA to differentiate morphotypes surpassing the limitations in other methods, being able to detect the response of morphological plasticity to environmental change. This is a critical piece in this study, leading to the assignment of practically all the morphometric variability that is quantified as a response of morphological plasticity of the variety/subspecies C. p. braarudii. While it would be theoretically coherent to assign all the morphometrical variability to C. p. braarudii, if this is the more common subspecies documented in the studied latitudes so far, this cannot be the only element of unilateral justification of the identification of morphological plasticity by IMMA, against possible substitution by different subspecies in the region during the last 250 kyr. Furthermore, the ranges of sizes fall within the limits documented for C. p. pelagicus in certain parts of the record. How can IMMA discriminate the presence of this subspecies and assign the variability withing that range of sizes to C. p. braarudii? This question needs to be better discussed and clarified. In overall, how is IMMA able to isolate/justify the detection of morphological plasticity is a question that deserves to be better explained, developed, and strengthened in the narrative of this manuscript. Despite this method (IMMA and MMA) has been successfully applied at the Iberian margin and served for the solid determination of C. p. braarudii vs. pelagicus dynamics at that area, the discussion and presentation of the practise should be raised here again for the new region of study.
The above mentioned implies an implementation of the information in materials and methods about IMMA application and a better and expanded explanation of the type of output data from this technique and interpretation. Furthermore, the manuscript would be benefited by extended information about the oceanography of the area of study. Following the scheme in Narciso (2006), a separated chapter about Core location and Oceanographic Setting would be desirable.
It is not clear what is the relationship between morphometrical/morphological variability in the results with conditions of primary productivity in the region. A better introduction and explanation of the regional conditions and the interpretation of the data from IMMA (already suggested) would help to solve this concern. But, also, the discussion of these important connections needs to be revised, clarified, and improved. A coherent discussion would be the direct comparison of the morphometrical patterns in this study with the available independent productivity record in the region (Moreno 2002), in order to validate the correspondence of morpho features with the changing conditions of productivity.
The quality of the presentation, as writing, organization and illustration of the data may be also improved. Below I provide a list of specific comments that I consider may be useful to address and improve the manuscript, following this general assessment
Specific comments
A more detailed presentation of the taxa/varieties/subspecies within C. pelagicus and its range of sizes under changing (natural and experimental) conditions is a missing element in the introduction. This would facilitate following the results and the subsequent interpretations in this manuscript.
35
What does “morphological plasticity” and/or “genetic plasticity” exactly mean? Please, improve the indroduction of these concepts and include complete definition and references.
55 to 65
This part of the introduction is of critical importance: How does the MMA tool overcome the mentioned limitation? What is the implementation in IMMA in comparison with MMA? I understand this information is included in the mentioned references by the same authors. But it is necessary to dig a lot into them to reach the point that is emphasized here. Please, provide a better detailed information about what is raised.
70
Instead of “survey”, I would suggest using “research” or “study”.
It would recommend substitution of “hole was performed” by “hole was drilled”.
The presentation of the area of study may be improved. The coordinates serve to give an indication, but it is difficult to locate so specifical locations, as the slope of Agadir, in a first approach. Please detail the location of the area of study from a higher to lower dymension (North Atlantic, west African coast, Canary region ... ).
It is confusing to mention the correspondence of the material with marine isotopic stages at the very beginning, without a previous introduction/indication about the details of the age model and range of absolute ages of the material. Please, rewrite the information about age model and age of the materials in a more coherent order.
Figure 1:
Latitude and longitude are required.
The representation of the main hydrological and oceanographic features of the region would improve this figure and its rol in the manuscrip, being the upwelling regime mentioned in the text the most important element. It would be also useful to have a very simple scheme of the most important surface currents affecting the region of study. The selected geographycal area could be reduced.
This figure could be combined with Figure 4 into one, being located at the beginning of the manuscript, together with the information about oceanography of the region.
85
Please, provide more detailed information about the preparation of slides for analysis. Is the amount of sediment used for slide preparation and the distribution of th material in the slide controlled?
“digitally evaluated (Narciso et al., 2006)” as it is exposed gives the impression that the mentioned measurements and data comes from the referred paper. If this methodological approach emulates the one already presented in that referred paper, please, modify the sentence with “digitally evaluated, following the procedure in Narciso et al. (2006)”.
95
What is the figure, table or data that give rise to the results presented in this paragraph?
After examination, I can establish connection between the components described in the text and the loadings in Figure 2, but this is not straightforward. How is evaluated the percentage of the variance of the mentioned components?
105
What is exactly “being active”? How is this information extracted from the output data from IMMA? How are the scores and counts evaluated to reach this determination?
Figure 3: It would be better to substitute the cm in Y Axis by Age. And the same comment could be applied to the rest of figures in the text after the presentation of the age model and the age of the materials.
Table 1: Please, include the p value or significance of these correlations.
115
“where only the larger morphotypes … are expected to be found”
“while C1 shows its variability in size due to paleoceanographic changes”
These important determinations are not directly extracted from the results in the current state of the narrative. Please provide further discussion, evidence or a reference supporting these important statements.
120
It is very difficult to follow the reasoning from “since” towards the end of the paragraph in this part of the text. As far as I understand, it is assumed that the variability in the C1 component is related to the morpho. variability within a single morphotype (instead of changes between morphotypes) because the range of size covered by the C1 is coherent with the definition of C. p. braarudii and/or because it is documented to be the unique expected morphotype in the region. If this is the case it is not clearly extracted from the narrative; please, rewrite, clarify and further discuss these important interpretations.
150
“during the Ice …” there are mistakes and repetitions in this sentence.
It is very difficult to follow a discussion in this sense, about specifical features such conditions and impacts during ice ages in the region, if the age of the sequence is not clearly specified, nor visible in the most of figures.
The presence of the small variety of C. pelagicus at Iberian latitudes during cold episode of the Quaternary is, indeed, an important fact to consider for the discussion in this study. As such, it should be better introduced and presented, from evidences in previous micropaleontological studies. From this, it would be necessary to directly address the question: why is C. p. pelagicus not considered to be a subspecies possibly present at the latitudes in this study during the selected interval? Provide references about, for example, the southernmost positioning of the polar front during the most extreme cold events of the Quaternary and the southernmost detection of this subspecies in fossil records to date.
165
The first sentence needs, at least, a reference, or more discussion.
Regarding the last sentence of the paragraph: I think it is, indeed, the power of this type of graph to determine the morphotype size boundaries what matters here. Please, reconsider this part of the text and provide more discussion on this regard.
175
“interpreting as reflecting normal (palaeoproductivity) conditions” If this interpretation comes from the data in this study, it should be better discussed before, as the connection is still not evident. If this comes from literature, a citation should be included.
“In some moments enhanced paleoproductivity … respectively” Please, clarify which are specifically the moments when these features are observed. A reference to figure with would help to follow that part of the text.
In the current state of the narrative, up to this part of the text, It is still not clear which are the relationship between enhanced paleoproductivity conditions and the smaller sC1 for the reader. Please review and reinforce this discussion and connection.
190
“Our results also show higher pp at ..” Again, this is not clearly discussed and extracted just from the data. The absence of reference to figure makes also difficult to follow and independently evaluate this interpretation.
Citation: https://doi.org/10.5194/cp-2023-31-RC1 -
RC2: 'Comment on cp-2023-31', Anonymous Referee #2, 30 Jun 2023
The manuscript "Coccolithus pelagicus subsp braarudii morphological plasticity in response to variations in the Canary region upwelling system over the past 250 ka" by Prista et al. investigates the morphometric variations of the species C. p. braarudii in the Canary region along the last 250 kyr by applying the Integrated Multivariate Morphon Analysis (IMMA). The data presented in this study are interesting and useful to clarify the plasticity of this specific species and its interconnection with the upwelling fluctuations and primary productivity, in an oceanographic context of particular interest for its peculiar sensitivity to upwelling variations. I found very interesting the application of a targeted statistical approach to better highlight different coccolithophore morphotypes, which may be a very useful tool to improve the investigation also of other species along other time intervals. Although, in my opinion the manuscript requires a strong reorganization and a better presentation of the obtained results, and the discussions need a more in-depth presentation. Moreover, I found that the organization and the displaying of figures and data are very similar to a previous paper from the same authors (Prista et al., 2020, http://doi.org/10.47894/mpal.66.6.06). Thus, it is difficult to see a significant novelty, if not for the fact that a different core that has been studied here compared to the previously published work. For this reason, I recommend to the authors finding new strategies to present their data, and to include a wider overview at global scale, not only regional, to improve the novelty of the manuscript. Thus, despite the interesting dataset, I think that at this stage the paper is not at the level required by a journal such as CP, and that a strong review of the entire manuscript is necessary. I reported below my suggestions on how I would improve the manuscript. I hope that my suggestions will be of help. Finally, although I am not a native speaker, I would suggest for a revision of the English before the re-submission.
Main comments:
- Age model is reported for the first time in Moreno et al 2001, not 2002 as reported in the manuscript. Modify this point at Line 76. I understand that the age model has been recalculated by the authors, although this point is not very clear, so why not using LR04 from Lisieki and Raymo (2005)? I also think that a clear presentation of similarities or differences of the new calibration with the previously published age model is necessary, also because Moreno et al. 2002 reported that “Calculation of carbonate fluxes to avoid dilution effects has not proved to be useful in this case mainly due to the error margin inherent to the age model construction”. This may be indicative that there is margin for improvements on the age model side.
- Age model interpolation has been done using a specific software? Please specify better how it has been constructed.
- Dedicate a section to the oceanographic setting, this is fundamental also for improving the discussion. Also subdivide better the material and method section with subsections dedicated to material and to the methodologies applied for sample preparation and analyses, and statistical treatment of the data.
- Lines 86-87: please specify which software/tool has been used to evaluate the size of placoliths.
- Results: I believe that the results need a broader presentation. Pay also attention to appropriately refer in the text to the figures; for example, Fig. 2 is never cited in the manuscript. This will help the reader in understanding the presented data. Describe the cut-off considered for defining the morphons, and improve the description of figure 3. Some figures have to be moved from the discussion to the result section (see my comments below).
- Discussion: in my opinion, the whole discussion needs to be reorganized to meet the level required by CP. It necessary to deepen the raised evidences to meet the journal scopes and topics. I would suggest to subdivide the discussion in three parts. 1) discuss more the evidence derived from the IMMA compared with other statistical approaches used for morphometric studies. As an example, Lines from 167 to 184 should be included in this section, as well as Figures 8 and 9 and their discussion at page 15. Explain the potential of IMMA underlying why using IMMA may be useful if applied also to other species and time intervals. This point would widen the audience interested in the manuscript and it can bring it further than the only regional setting. 2) Section on the linkages between the identified morphons and the paleoproductivity/ upwelling of this area area. 3) Evidences/linkages over time between C. p. braarudii morphons, upwelling fluctuations, primary productivity, glacial-interglacial cycles of the last 280 kyr. A more in-depth comparison and discussion with the literature available for the studied area, e.g. Prista et al 2020, Narciso et al. 2006, is strongly recommended to improve the quality of the discussion. Also a wider perspective is strongly suggested, considering the evidences available for C. p. braarudii in other oceanic areas. I would also suggest to produce a final figure summarizing the most interesting outcomes, possibly adding a few data available from the literature that corroborate the hypothesis of the authors (e.g., TOC, Ba, paleoproductivity proxy).
- Modify the conclusion accordingly to what suggested for the discussion section.
- All the figures have a very poor quality, this needs to be strongly improved. I have noticed the same low quality and mistakes are present on a paper similar to this one on this subject from the authors (Prista et al., 2020). Moreover, the figures 2, 3, 5, 6, 7, 8 are similar to many figures published in Prista et al., 2020, although for a different site in the West coast of Iberia. I understand that the statistical approach is the same, which is fine, but in my opinion a better effort is mandatory to differentiate the papers, making also the figure display more efficient and tailored to the new paper. Similarities among the figures of the two works make also difficult to identify the novelty of the manuscript.
- Please change all over the manuscript, table, figures, and supplementary the comma with the dot when it comes to decimal number. Make sure to follow the English rules.
- Supplementary material needs captions and to be subdivided in two different tables, so they can be referred appropriately along the manuscript. The key points of the age model need to be reported as Table S1, before the next table that it is cited later in the manuscript. Move the age model key point in the first page of the supplementary.
- Pay attention to the references’ format along the manuscript, it is not always uniform.
Detailed comments:
- Lines 15-16 are exactly the same words used in Lines 59-60. Please modify either in the abstract or in the introduction.
- Line 16: change “To address this limitation,”
- Line 17: change “was developed” with “was here applied”. In the previous form it seemed that the IMMA is reported in this work for the first time, but it has been previously published in Prista et al., 2020.
- Line 18: change “different placolith morphotypes regarding maximum coccolith length within Quaternary GeoB5559-2 samples”
- Lines 19-20: change “The results show that IMMA and morphometry microvariations can be used to extract information on upwelling intensity and primary productivity fluctuations”
- Line 20: change “extracting” to avoid repetition with the sentence above.
- Lines 21-22: Size variations and morphotypes can be affected also by other environmental parameters, so I think it is better to state that IMMA is a useful tool to extract information on specific environmental parameters/climate changes, but it does not reflect necessarily upwelling. Moreover, defining this only on the basis of one case-study is too limiting. I suggest to change this last sentence to make it more generic on the potential of IMMA for past climate studies or/and be specific on what you can derive from this analysis at your site. For example, you can change with “Thus, in our case-study IMMA was a great potential tool for studies”.
- Lines 25-26: change “making them ideal tools for studies on biostratigraphy, evolution and palaeoceanography of the Mesozoic and Cenozoic, with many of the taxa appearing during the Cenozoic epochs still extant”
- Lines 31-32: change “since detecting the morphological responses to environmental changes”
- Line 33: change “we consider”. Never use the contracted form in a text.
- Lines 33-34: change “Coccolithus pelagicus s.l. which is one of the most interesting taxa that evolved during the Cenozoic.”. Please, add also specifics on why is C. pelagicus one of the most interesting taxa. This sentence also needs to be supported by references.
- Lines 35: add references to the sentence as well as the age to the first appearance of C. pelagicus: It appeared in the fossil record at the beginning of the Palaeocene stage (Reference needed+age) and still thrives in present day oceans (Reference needed).
- Lines 35-37: instead of the references on the Cenozoic climate events, it is more pertinent to include the references concerning the C. pelagicus adaptability to the changes thanks to its plasticity. Remove Zachos et al., 2001, 2008 and add appropriate references.
- Lines 38-39: this sentence is not clear, please rephrase it. It is also necessary to add references at the end of the sentence regarding the observed changes in morphology and paleogeography.
- Line 42: change “Although the high speed of coccolithophores’ generation is a great challenge”
- Line 50: please be more specific and extent the description about the different morphotypes of C. pelagicus. If you always refer to C. p. braarudii for your data, make sure that you always you the same name in the whole manuscript.
- Lines 56-65: here it is necessary to be more specific on the limitation of the other statistical approaches and what it is the advantage in using the IMMA.
- Line 64: change “renamed Integrated”
- Line 70: change “The hole was drilled”
- Line 71: change “from Marine Isotope Stage (MIS)”. Also add the reference.
- Lines 71-73: explain better how the upwelling affects the sediment core.
- Line 74: specify the sample depth interval that you are studying, from xxx cm to xxx cm depth.
- Line 75: specify if the d18O data are from benthic or planktic foraminifera, which species?
- Line 84: add the reference for the sample preparation.
- Line 85: change “to collect placolith”
- Line 86: change “For studying the morphometry, 100 placoliths of C. pelagicus”
- Line 91: Change “ 0.1 micron each. This approach allows defining the morphotypes”
- Line 118: specify which are the results that support your evidence, as well as the figures. It is not clear.
- Lines 132-135: move these lines to the oceanographic settings.
- Lines 147-148: add references to “nearly permanent to intermittent” (REF), and to “ more seasonal character” (REF).
- Line 150: add reference to document the absence of C. pelagicus during the ice ages. Also define “ice ages” with specific time intervals, or MIS, or specific ages.
- Line 221: this needs to be better justified.
- Lines 230, 237, 243: do not refer to depth but to age instead.
Figures and Tables
- Figure 1. is missing the scale, latitude and longitude. It would be useful to show also the morphology of the ocean floor that allows identifying the localization of the Agadir mountain slope. It may be also useful to discuss upwelling currents. It is also necessary to add the main current affecting the area. I suggest to include Figure 4 as Fig. 1B, which need to specify better how it has been constructed starting from what available in Sangrà et al. 2009.
- Figure 2: divide this figure in A and B, so the X axis can be repeated for both the graphs. Include in both A and B vertical lines to delimit the 3 morphotypes identified (2 for C1 and 1 for C2) to make the identification of the 3 groups clearer. Remove the horizontal dotted lines, leaving only the one considered useful (the cut-off) for identifying the morphons. Pay attention to the style of the text, it does not look even in the figure.
- Figure 3: Plot the data against age, not depth, and add the MIS as well as colored bands to help the reader in following the different MIS.
- Table 1: include also p-values. Make clearer what is meant with morphotype counting.
- Figure 5: move this figure as the first one presented in the results. Units are missing as well as the definition of axis Y. Make this figure smaller, it can be merged with figure 2.
- Figure 6: this is a result, move it to the right section and present the data. Add the unit to the X axis of the mean and median as well as to the d18O. In the caption the mean and median are not mentioned as well as the d18O reference and specifics on planktonic or benthic.
- Figure 7: remove this figure as it shows exaclty the same data reported in figure 6. It is not informative. To justify the correlation between IMMA C1 and mean-median size perform a Pearson correlation, and specify also the p-value (see Lines 210-212).
- Figure 8: the caption of this figure is the same as figure 11 in Prista et al (2020), except the site name. Please modify.
- Figure 9: use the age instead of the sample, in the caption specify both. Add the unit and definition of axis X that is missing for all the histograms.
Citation: https://doi.org/10.5194/cp-2023-31-RC2
Status: closed
-
RC1: 'Comment on cp-2023-31', Anonymous Referee #1, 20 Jun 2023
General Comments
The manuscript by Prista et al. presents a morphometric record of C. pelagicus, unprecedented in the Canary region for the last 250 kyr, focussed on the application of the Integrated Multivariate Morphon Analysis (IMMA) tool. From their results, the authors suggest the microvariations observed to be considered as response of morphological plasticity of C. p. braarudii to upwelling intensity and primary productivity conditions in the region, supporting the use of IMMA as a tool to track short-term climate effects on coccolith morphometry during the Quaternary.
The data in this study is of quality, great novelty and the contribution is valuable for the region of study. The topic in this research is also of general interest and of important potential use, either for the nannoplankton community or for scientists interested in paleoclimatic/paleoceanographic reconstructions. Thus, the manuscript represents a contribution which is clearly within the scope of CP. However, some of the determinations in this study are not yet entirely supported, at least in the current state in which the data is presented and discussed, giving rise to a scientific quality of the manuscript that could be improved.
The manuscript emphasizes the ability of IMMA to differentiate morphotypes surpassing the limitations in other methods, being able to detect the response of morphological plasticity to environmental change. This is a critical piece in this study, leading to the assignment of practically all the morphometric variability that is quantified as a response of morphological plasticity of the variety/subspecies C. p. braarudii. While it would be theoretically coherent to assign all the morphometrical variability to C. p. braarudii, if this is the more common subspecies documented in the studied latitudes so far, this cannot be the only element of unilateral justification of the identification of morphological plasticity by IMMA, against possible substitution by different subspecies in the region during the last 250 kyr. Furthermore, the ranges of sizes fall within the limits documented for C. p. pelagicus in certain parts of the record. How can IMMA discriminate the presence of this subspecies and assign the variability withing that range of sizes to C. p. braarudii? This question needs to be better discussed and clarified. In overall, how is IMMA able to isolate/justify the detection of morphological plasticity is a question that deserves to be better explained, developed, and strengthened in the narrative of this manuscript. Despite this method (IMMA and MMA) has been successfully applied at the Iberian margin and served for the solid determination of C. p. braarudii vs. pelagicus dynamics at that area, the discussion and presentation of the practise should be raised here again for the new region of study.
The above mentioned implies an implementation of the information in materials and methods about IMMA application and a better and expanded explanation of the type of output data from this technique and interpretation. Furthermore, the manuscript would be benefited by extended information about the oceanography of the area of study. Following the scheme in Narciso (2006), a separated chapter about Core location and Oceanographic Setting would be desirable.
It is not clear what is the relationship between morphometrical/morphological variability in the results with conditions of primary productivity in the region. A better introduction and explanation of the regional conditions and the interpretation of the data from IMMA (already suggested) would help to solve this concern. But, also, the discussion of these important connections needs to be revised, clarified, and improved. A coherent discussion would be the direct comparison of the morphometrical patterns in this study with the available independent productivity record in the region (Moreno 2002), in order to validate the correspondence of morpho features with the changing conditions of productivity.
The quality of the presentation, as writing, organization and illustration of the data may be also improved. Below I provide a list of specific comments that I consider may be useful to address and improve the manuscript, following this general assessment
Specific comments
A more detailed presentation of the taxa/varieties/subspecies within C. pelagicus and its range of sizes under changing (natural and experimental) conditions is a missing element in the introduction. This would facilitate following the results and the subsequent interpretations in this manuscript.
35
What does “morphological plasticity” and/or “genetic plasticity” exactly mean? Please, improve the indroduction of these concepts and include complete definition and references.
55 to 65
This part of the introduction is of critical importance: How does the MMA tool overcome the mentioned limitation? What is the implementation in IMMA in comparison with MMA? I understand this information is included in the mentioned references by the same authors. But it is necessary to dig a lot into them to reach the point that is emphasized here. Please, provide a better detailed information about what is raised.
70
Instead of “survey”, I would suggest using “research” or “study”.
It would recommend substitution of “hole was performed” by “hole was drilled”.
The presentation of the area of study may be improved. The coordinates serve to give an indication, but it is difficult to locate so specifical locations, as the slope of Agadir, in a first approach. Please detail the location of the area of study from a higher to lower dymension (North Atlantic, west African coast, Canary region ... ).
It is confusing to mention the correspondence of the material with marine isotopic stages at the very beginning, without a previous introduction/indication about the details of the age model and range of absolute ages of the material. Please, rewrite the information about age model and age of the materials in a more coherent order.
Figure 1:
Latitude and longitude are required.
The representation of the main hydrological and oceanographic features of the region would improve this figure and its rol in the manuscrip, being the upwelling regime mentioned in the text the most important element. It would be also useful to have a very simple scheme of the most important surface currents affecting the region of study. The selected geographycal area could be reduced.
This figure could be combined with Figure 4 into one, being located at the beginning of the manuscript, together with the information about oceanography of the region.
85
Please, provide more detailed information about the preparation of slides for analysis. Is the amount of sediment used for slide preparation and the distribution of th material in the slide controlled?
“digitally evaluated (Narciso et al., 2006)” as it is exposed gives the impression that the mentioned measurements and data comes from the referred paper. If this methodological approach emulates the one already presented in that referred paper, please, modify the sentence with “digitally evaluated, following the procedure in Narciso et al. (2006)”.
95
What is the figure, table or data that give rise to the results presented in this paragraph?
After examination, I can establish connection between the components described in the text and the loadings in Figure 2, but this is not straightforward. How is evaluated the percentage of the variance of the mentioned components?
105
What is exactly “being active”? How is this information extracted from the output data from IMMA? How are the scores and counts evaluated to reach this determination?
Figure 3: It would be better to substitute the cm in Y Axis by Age. And the same comment could be applied to the rest of figures in the text after the presentation of the age model and the age of the materials.
Table 1: Please, include the p value or significance of these correlations.
115
“where only the larger morphotypes … are expected to be found”
“while C1 shows its variability in size due to paleoceanographic changes”
These important determinations are not directly extracted from the results in the current state of the narrative. Please provide further discussion, evidence or a reference supporting these important statements.
120
It is very difficult to follow the reasoning from “since” towards the end of the paragraph in this part of the text. As far as I understand, it is assumed that the variability in the C1 component is related to the morpho. variability within a single morphotype (instead of changes between morphotypes) because the range of size covered by the C1 is coherent with the definition of C. p. braarudii and/or because it is documented to be the unique expected morphotype in the region. If this is the case it is not clearly extracted from the narrative; please, rewrite, clarify and further discuss these important interpretations.
150
“during the Ice …” there are mistakes and repetitions in this sentence.
It is very difficult to follow a discussion in this sense, about specifical features such conditions and impacts during ice ages in the region, if the age of the sequence is not clearly specified, nor visible in the most of figures.
The presence of the small variety of C. pelagicus at Iberian latitudes during cold episode of the Quaternary is, indeed, an important fact to consider for the discussion in this study. As such, it should be better introduced and presented, from evidences in previous micropaleontological studies. From this, it would be necessary to directly address the question: why is C. p. pelagicus not considered to be a subspecies possibly present at the latitudes in this study during the selected interval? Provide references about, for example, the southernmost positioning of the polar front during the most extreme cold events of the Quaternary and the southernmost detection of this subspecies in fossil records to date.
165
The first sentence needs, at least, a reference, or more discussion.
Regarding the last sentence of the paragraph: I think it is, indeed, the power of this type of graph to determine the morphotype size boundaries what matters here. Please, reconsider this part of the text and provide more discussion on this regard.
175
“interpreting as reflecting normal (palaeoproductivity) conditions” If this interpretation comes from the data in this study, it should be better discussed before, as the connection is still not evident. If this comes from literature, a citation should be included.
“In some moments enhanced paleoproductivity … respectively” Please, clarify which are specifically the moments when these features are observed. A reference to figure with would help to follow that part of the text.
In the current state of the narrative, up to this part of the text, It is still not clear which are the relationship between enhanced paleoproductivity conditions and the smaller sC1 for the reader. Please review and reinforce this discussion and connection.
190
“Our results also show higher pp at ..” Again, this is not clearly discussed and extracted just from the data. The absence of reference to figure makes also difficult to follow and independently evaluate this interpretation.
Citation: https://doi.org/10.5194/cp-2023-31-RC1 -
RC2: 'Comment on cp-2023-31', Anonymous Referee #2, 30 Jun 2023
The manuscript "Coccolithus pelagicus subsp braarudii morphological plasticity in response to variations in the Canary region upwelling system over the past 250 ka" by Prista et al. investigates the morphometric variations of the species C. p. braarudii in the Canary region along the last 250 kyr by applying the Integrated Multivariate Morphon Analysis (IMMA). The data presented in this study are interesting and useful to clarify the plasticity of this specific species and its interconnection with the upwelling fluctuations and primary productivity, in an oceanographic context of particular interest for its peculiar sensitivity to upwelling variations. I found very interesting the application of a targeted statistical approach to better highlight different coccolithophore morphotypes, which may be a very useful tool to improve the investigation also of other species along other time intervals. Although, in my opinion the manuscript requires a strong reorganization and a better presentation of the obtained results, and the discussions need a more in-depth presentation. Moreover, I found that the organization and the displaying of figures and data are very similar to a previous paper from the same authors (Prista et al., 2020, http://doi.org/10.47894/mpal.66.6.06). Thus, it is difficult to see a significant novelty, if not for the fact that a different core that has been studied here compared to the previously published work. For this reason, I recommend to the authors finding new strategies to present their data, and to include a wider overview at global scale, not only regional, to improve the novelty of the manuscript. Thus, despite the interesting dataset, I think that at this stage the paper is not at the level required by a journal such as CP, and that a strong review of the entire manuscript is necessary. I reported below my suggestions on how I would improve the manuscript. I hope that my suggestions will be of help. Finally, although I am not a native speaker, I would suggest for a revision of the English before the re-submission.
Main comments:
- Age model is reported for the first time in Moreno et al 2001, not 2002 as reported in the manuscript. Modify this point at Line 76. I understand that the age model has been recalculated by the authors, although this point is not very clear, so why not using LR04 from Lisieki and Raymo (2005)? I also think that a clear presentation of similarities or differences of the new calibration with the previously published age model is necessary, also because Moreno et al. 2002 reported that “Calculation of carbonate fluxes to avoid dilution effects has not proved to be useful in this case mainly due to the error margin inherent to the age model construction”. This may be indicative that there is margin for improvements on the age model side.
- Age model interpolation has been done using a specific software? Please specify better how it has been constructed.
- Dedicate a section to the oceanographic setting, this is fundamental also for improving the discussion. Also subdivide better the material and method section with subsections dedicated to material and to the methodologies applied for sample preparation and analyses, and statistical treatment of the data.
- Lines 86-87: please specify which software/tool has been used to evaluate the size of placoliths.
- Results: I believe that the results need a broader presentation. Pay also attention to appropriately refer in the text to the figures; for example, Fig. 2 is never cited in the manuscript. This will help the reader in understanding the presented data. Describe the cut-off considered for defining the morphons, and improve the description of figure 3. Some figures have to be moved from the discussion to the result section (see my comments below).
- Discussion: in my opinion, the whole discussion needs to be reorganized to meet the level required by CP. It necessary to deepen the raised evidences to meet the journal scopes and topics. I would suggest to subdivide the discussion in three parts. 1) discuss more the evidence derived from the IMMA compared with other statistical approaches used for morphometric studies. As an example, Lines from 167 to 184 should be included in this section, as well as Figures 8 and 9 and their discussion at page 15. Explain the potential of IMMA underlying why using IMMA may be useful if applied also to other species and time intervals. This point would widen the audience interested in the manuscript and it can bring it further than the only regional setting. 2) Section on the linkages between the identified morphons and the paleoproductivity/ upwelling of this area area. 3) Evidences/linkages over time between C. p. braarudii morphons, upwelling fluctuations, primary productivity, glacial-interglacial cycles of the last 280 kyr. A more in-depth comparison and discussion with the literature available for the studied area, e.g. Prista et al 2020, Narciso et al. 2006, is strongly recommended to improve the quality of the discussion. Also a wider perspective is strongly suggested, considering the evidences available for C. p. braarudii in other oceanic areas. I would also suggest to produce a final figure summarizing the most interesting outcomes, possibly adding a few data available from the literature that corroborate the hypothesis of the authors (e.g., TOC, Ba, paleoproductivity proxy).
- Modify the conclusion accordingly to what suggested for the discussion section.
- All the figures have a very poor quality, this needs to be strongly improved. I have noticed the same low quality and mistakes are present on a paper similar to this one on this subject from the authors (Prista et al., 2020). Moreover, the figures 2, 3, 5, 6, 7, 8 are similar to many figures published in Prista et al., 2020, although for a different site in the West coast of Iberia. I understand that the statistical approach is the same, which is fine, but in my opinion a better effort is mandatory to differentiate the papers, making also the figure display more efficient and tailored to the new paper. Similarities among the figures of the two works make also difficult to identify the novelty of the manuscript.
- Please change all over the manuscript, table, figures, and supplementary the comma with the dot when it comes to decimal number. Make sure to follow the English rules.
- Supplementary material needs captions and to be subdivided in two different tables, so they can be referred appropriately along the manuscript. The key points of the age model need to be reported as Table S1, before the next table that it is cited later in the manuscript. Move the age model key point in the first page of the supplementary.
- Pay attention to the references’ format along the manuscript, it is not always uniform.
Detailed comments:
- Lines 15-16 are exactly the same words used in Lines 59-60. Please modify either in the abstract or in the introduction.
- Line 16: change “To address this limitation,”
- Line 17: change “was developed” with “was here applied”. In the previous form it seemed that the IMMA is reported in this work for the first time, but it has been previously published in Prista et al., 2020.
- Line 18: change “different placolith morphotypes regarding maximum coccolith length within Quaternary GeoB5559-2 samples”
- Lines 19-20: change “The results show that IMMA and morphometry microvariations can be used to extract information on upwelling intensity and primary productivity fluctuations”
- Line 20: change “extracting” to avoid repetition with the sentence above.
- Lines 21-22: Size variations and morphotypes can be affected also by other environmental parameters, so I think it is better to state that IMMA is a useful tool to extract information on specific environmental parameters/climate changes, but it does not reflect necessarily upwelling. Moreover, defining this only on the basis of one case-study is too limiting. I suggest to change this last sentence to make it more generic on the potential of IMMA for past climate studies or/and be specific on what you can derive from this analysis at your site. For example, you can change with “Thus, in our case-study IMMA was a great potential tool for studies”.
- Lines 25-26: change “making them ideal tools for studies on biostratigraphy, evolution and palaeoceanography of the Mesozoic and Cenozoic, with many of the taxa appearing during the Cenozoic epochs still extant”
- Lines 31-32: change “since detecting the morphological responses to environmental changes”
- Line 33: change “we consider”. Never use the contracted form in a text.
- Lines 33-34: change “Coccolithus pelagicus s.l. which is one of the most interesting taxa that evolved during the Cenozoic.”. Please, add also specifics on why is C. pelagicus one of the most interesting taxa. This sentence also needs to be supported by references.
- Lines 35: add references to the sentence as well as the age to the first appearance of C. pelagicus: It appeared in the fossil record at the beginning of the Palaeocene stage (Reference needed+age) and still thrives in present day oceans (Reference needed).
- Lines 35-37: instead of the references on the Cenozoic climate events, it is more pertinent to include the references concerning the C. pelagicus adaptability to the changes thanks to its plasticity. Remove Zachos et al., 2001, 2008 and add appropriate references.
- Lines 38-39: this sentence is not clear, please rephrase it. It is also necessary to add references at the end of the sentence regarding the observed changes in morphology and paleogeography.
- Line 42: change “Although the high speed of coccolithophores’ generation is a great challenge”
- Line 50: please be more specific and extent the description about the different morphotypes of C. pelagicus. If you always refer to C. p. braarudii for your data, make sure that you always you the same name in the whole manuscript.
- Lines 56-65: here it is necessary to be more specific on the limitation of the other statistical approaches and what it is the advantage in using the IMMA.
- Line 64: change “renamed Integrated”
- Line 70: change “The hole was drilled”
- Line 71: change “from Marine Isotope Stage (MIS)”. Also add the reference.
- Lines 71-73: explain better how the upwelling affects the sediment core.
- Line 74: specify the sample depth interval that you are studying, from xxx cm to xxx cm depth.
- Line 75: specify if the d18O data are from benthic or planktic foraminifera, which species?
- Line 84: add the reference for the sample preparation.
- Line 85: change “to collect placolith”
- Line 86: change “For studying the morphometry, 100 placoliths of C. pelagicus”
- Line 91: Change “ 0.1 micron each. This approach allows defining the morphotypes”
- Line 118: specify which are the results that support your evidence, as well as the figures. It is not clear.
- Lines 132-135: move these lines to the oceanographic settings.
- Lines 147-148: add references to “nearly permanent to intermittent” (REF), and to “ more seasonal character” (REF).
- Line 150: add reference to document the absence of C. pelagicus during the ice ages. Also define “ice ages” with specific time intervals, or MIS, or specific ages.
- Line 221: this needs to be better justified.
- Lines 230, 237, 243: do not refer to depth but to age instead.
Figures and Tables
- Figure 1. is missing the scale, latitude and longitude. It would be useful to show also the morphology of the ocean floor that allows identifying the localization of the Agadir mountain slope. It may be also useful to discuss upwelling currents. It is also necessary to add the main current affecting the area. I suggest to include Figure 4 as Fig. 1B, which need to specify better how it has been constructed starting from what available in Sangrà et al. 2009.
- Figure 2: divide this figure in A and B, so the X axis can be repeated for both the graphs. Include in both A and B vertical lines to delimit the 3 morphotypes identified (2 for C1 and 1 for C2) to make the identification of the 3 groups clearer. Remove the horizontal dotted lines, leaving only the one considered useful (the cut-off) for identifying the morphons. Pay attention to the style of the text, it does not look even in the figure.
- Figure 3: Plot the data against age, not depth, and add the MIS as well as colored bands to help the reader in following the different MIS.
- Table 1: include also p-values. Make clearer what is meant with morphotype counting.
- Figure 5: move this figure as the first one presented in the results. Units are missing as well as the definition of axis Y. Make this figure smaller, it can be merged with figure 2.
- Figure 6: this is a result, move it to the right section and present the data. Add the unit to the X axis of the mean and median as well as to the d18O. In the caption the mean and median are not mentioned as well as the d18O reference and specifics on planktonic or benthic.
- Figure 7: remove this figure as it shows exaclty the same data reported in figure 6. It is not informative. To justify the correlation between IMMA C1 and mean-median size perform a Pearson correlation, and specify also the p-value (see Lines 210-212).
- Figure 8: the caption of this figure is the same as figure 11 in Prista et al (2020), except the site name. Please modify.
- Figure 9: use the age instead of the sample, in the caption specify both. Add the unit and definition of axis X that is missing for all the histograms.
Citation: https://doi.org/10.5194/cp-2023-31-RC2
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