Surficial Sediment Distribution in a Complex Marine Setting—The Example of Coastal and Open Sea Areas of Evia Island, Central Aegean, Greece
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReview report
Oceans Article: Surficial Sediment distribution in a complex marine setting- The example of coastal and open sea areas of Evia Island, Central Aegean, Greece by Irene Zananiri and Ioannis Vakalas
Summary:
The article is an interesting synthesis on sediment distribution and dynamics in a complex sea area. It is based on analyses of own research material (sediment samples) as well as summaries of earlier studies from the area with an aim to explain the processes affecting sediment distribution in the area. The authors have managed to add a large amount of information to the common knowledge of this sea area. The conclusions are eligible, but due to some unclear interpretations (perhaps misspellings or errors in translations to English) still slightly decreasing the quality. I believe that these can be sorted out so that the paper can be published.
Article: The study is well planned and executed and the results are certainly of value for common knowledge and further studies on the complex mechanisms controlling sediment distribution and dynamics in the Aegean Sea. There are no methodological inaccuracies nor missing controls.
Review: I believe that the article is of good value in spite of in my mind some contradictory statements on as few points in the text (perhaps misspellings or errors in translations to English). They are all pointed out in my review below, and it should be possible to check/correct these.
I see this publication as a good paper on sediment dynamics in the Aegean sea, provided that some errors/uncertainties are corrected.
Comments:
On line 166 the authors state that “neither gravel nor pure sand/mud is prevalent.”, this, however, doesn’t seem true if you look at the Folk diagram /(Fig. 3 where a lot of samples plot very close to the pure Mud corner.
Figure 1. Sea area north of Crete is on the map called Creatan Sea. I might be wrong, but I believe that the sea area is called Cretan Sea.
For the reader it is confusing when the authors use two different names for the same water area, South Evoikos (Gulf) in figure 1 and South Euboean Gulf in figure 2 (and other figures later). As only Evoikos has been used in text I suggest that Euboean in figure 2 (and figures 4, 5, 10 and 11) is changed to Evoikos.
Figure 5. Two typos. In top picture legend “mean szie” instead of mean size and in middle picture legend “soring” instead of sorting.
Chapter 3.3 (lines 257 to 262) Line 257-258 says “In South Evoikos Gulf sediment transport is directed along the narrow strait”. First of all what is meant here with “strait”, the Euripus Strait, the strait between South Evoikos Gulf and Petalioi Gulf at Kavalliani island or perhaps the South Evoikos Gulf itself. It is hard to understand what is meant here. If the gulf itself is meant with the word “strait” I have hard to see any clear transport pattern along the gulf. There are only a couple of arrows that follow an imagined centre line of the gulf. I would omit this sentence.
When authors write about Petalioi Gulf (line 260) “In Petalioi Gulf, sediment transport is predominantly directed toward the southwest” the authors must have another map that the one provided to me. There is not one single arrow (except for one very small one at the extreme bottom directed towards WSW) which would be directed towards SW. I don’t understand this situation. Please rewrite so that this is understandable, or if wrong map is attached to the proof, then please change to the correct one.
The following sentence is even more confusing “In the open sea area between the Western coast of Evia and Skyros island”… Between Western coast of Evia and Skyros island is Evia Island and the Agean Sea. I believe that here is meant “between the Eastern coast of Evia and the island of Skyros…” , continuing on lines 264-266 “sediment transport shows a northward trend, oriented vertically to the coastline, indicating that materials are being carried southward towards the open Aegean Sea”. Perhaps northward transport is meant?
On lines 272-275 it is said that “In Skyros and the open sea around the island, transport vectors suggest a radial transport pattern, with sediments being dispersed outward from the island. This pattern may result from wave-driven processes and open-sea currents that radiate sediment from the coast into the surrounding waters”. To me it looks that the sediment is transported in a non-radial pattern, directing the transport into the -600 meters depth area as almost all arrows point at that direction. I suggest editing of this statement.
4.1. Water circulation in Central Aegean: there is no reference to figure 1, which shows the circulation patterns discussed. Please add reference in the beginning of the text explaining water circulation in the Aegean Sea.
Line 377-379 “…strong northwestward transport vectors are observed near the northern end of the gulf, particularly as water flows into the Euripus Strait”. This is at least not evidenced by Figure 11 (which, however, is not referenced to) as there are no such vectors in northwest, but such are shown in Southwestern part of the gulf near the Euripus strait, which also could be evidenced by water inflow through Euripus strait from South Evoikos Gulf. Perhaps just a misspelling if “northern end” was meant to be “southern end”. Please correct if so.
Line 428 “(mean size, sorting skewness)” I guess that it is missing a comma (mean size, sorting, skewness).
Line 452 “sand-dominated sediments” Tome it looks more like silt-dominated sediments in South Evoikos Gulf and near Chalkis.
Line 458 I still have hard to see a general northward flow in South Evoikos Gulf. Definitely there is one in the southernmost part at the strait between Agia Marina and Kavalliani, but not in general in the gulf in my mind. Only the arrows in Figure 11 (From reference 44 Tsirogiannis et al. 2019) do support this statement. On the other hand the reference seems trustworthy, so I can accept the statement of such flow, in spite of poor evidence figure 7.
I suggest acceptance after minor revisions.
Comments on the Quality of English LanguageThe English is in general good, but I believe that some uncertainties of main directions (North, East, South, West) are due to errors in translation. These are the main (almost only) problems with the whole article. After they are corrected the article will be fine for publication.
Author Response
Response to reviewer 1 comments
We sincerely appreciate your constructive comments. Please find below our responses and the revisions we have made to the manuscript in accordance with your suggestions.
On line 166 the authors state that “neither gravel nor pure sand/mud is prevalent.”, this, however, doesn’t seem true if you look at the Folk diagram /(Fig. 3 where a lot of samples plot very close to the pure Mud corner.
Response: The text has been reformed as following:
On the Folk classification diagram, most of the measured samples lie near the sand-mud boundary at the bottom, indicating a dominance of sand-mud mixtures, with almost ab-sence of gravel or pure sand
Figure 1. Sea area north of Crete is on the map called Creatan Sea. I might be wrong, but I believe that the sea area is called Cretan Sea.
Response: In order to overcome the spelling issue, it has been renamed to Sea of Crete
For the reader it is confusing when the authors use two different names for the same water area, South Evoikos (Gulf) in figure 1 and South Euboean Gulf in figure 2 (and other figures later). As only Evoikos has been used in text I suggest that Euboean in figure 2 (and figures 4, 5, 10 and 11) is changed to Evoikos.
Response: Evoikos Gulf has been applied to figs. 4, 5, 10 and 11.
Figure 5. Two typos. In top picture legend “mean szie” instead of mean size and in middle picture legend “soring” instead of sorting.
Response: Typos have been corrected
Chapter 3.3 (lines 257 to 262) Line 257-258 says “In South Evoikos Gulf sediment transport is directed along the narrow strait”. First of all what is meant here with “strait”, the Euripus Strait, the strait between South Evoikos Gulf and Petalioi Gulf at Kavalliani island or perhaps the South Evoikos Gulf itself. It is hard to understand what is meant here. If the gulf itself is meant with the word “strait” I have hard to see any clear transport pattern along the gulf. There are only a couple of arrows that follow an imagined centre line of the gulf. I would omit this sentence.
Response: Lines 257-258 have been rewritten to make sense: “In South Evoikos Gulf sediment transport is mostly oriented vertical to the coastlines while at the central parts bidirectional transport vector pattern can be implied.”
When authors write about Petalioi Gulf (line 260) “In Petalioi Gulf, sediment transport is predominantly directed toward the southwest” the authors must have another map that the one provided to me. There is not one single arrow (except for one very small one at the extreme bottom directed towards WSW) which would be directed towards SW. I don’t understand this situation. Please rewrite so that this is understandable, or if wrong map is attached to the proof, then please change to the correct one.
Response: There was a typo in the specific like (SW instead of NW). The whole paragraph has been rephrased as follows:
“In Petalioi Gulf, sediment transport is predominantly directed toward the northwest. The arrows in this area suggest that sediments are moving away from the coast following ENE directions in Attica Penninsula and WNE in South Evia, and close to the entrance of South Evoikos Gulf are oriented NW. This dispersion pattern can be suggested that it is driven by marine currents.”
The following sentence is even more confusing “In the open sea area between the Western coast of Evia and Skyros island”… Between Western coast of Evia and Skyros island is Evia Island and the Agean Sea. I believe that here is meant “between the Eastern coast of Evia and the island of Skyros…” , continuing on lines 264-266 “sediment transport shows a northward trend, oriented vertically to the coastline, indicating that materials are being carried southward towards the open Aegean Sea”. Perhaps northward transport is meant?
Response: Of course, the write term is Eastern coast and has been corrected. Northwards transport instead of trend was also applied.
On lines 272-275 it is said that “In Skyros and the open sea around the island, transport vectors suggest a radial transport pattern, with sediments being dispersed outward from the island. This pattern may result from wave-driven processes and open-sea currents that radiate sediment from the coast into the surrounding waters”. To me it looks that the sediment is transported in a non-radial pattern, directing the transport into the -600 meters depth area as almost all arrows point at that direction. I suggest editing of this statement.
Response: The term radial has been omitted and the phrase was rewritten: “transport vectors suggest transport pattern towards the deeper parts of the basin,…”
4.1. Water circulation in Central Aegean: there is no reference to figure 1, which shows the circulation patterns discussed. Please add reference in the beginning of the text explaining water circulation in the Aegean Sea.
Response: A new figure has been added (Figure 11) where the Aegean Sea circulation pattern is displayed.
Line 377-379 “…strong northwestward transport vectors are observed near the northern end of the gulf, particularly as water flows into the Euripus Strait”. This is at least not evidenced by Figure 11 (which, however, is not referenced to) as there are no such vectors in northwest, but such are shown in Southwestern part of the gulf near the Euripus strait, which also could be evidenced by water inflow through Euripus strait from South Evoikos Gulf. Perhaps just a misspelling if “northern end” was meant to be “southern end”. Please correct if so.
Misspelling corrected, southern end was the correct term.
Line 428 “(mean size, sorting skewness)” I guess that it is missing a comma (mean size, sorting, skewness).
Response: Comma added.
Line 452 “sand-dominated sediments” Tome it looks more like silt-dominated sediments in South Evoikos Gulf and near Chalkis.
Response: The whole sentences has been revised as follows: In South Evoikos Gulf, and areas near Chalkis mud-dominated sediments with slightly better sorting and positive skewness are prevalent while Petalioi Gulf are characterized by sand-dominated deposits more positively skewed.
Line 458 I still have hard to see a general northward flow in South Evoikos Gulf. Definitely there is one in the southernmost part at the strait between Agia Marina and Kavalliani, but not in general in the gulf in my mind. Only the arrows in Figure 11 (From reference 44 Tsirogiannis et al. 2019) do support this statement. On the other hand the reference seems trustworthy, so I can accept the statement of such flow, in spite of poor evidence figure 7.
Response: The circulation maps proposed by Tsirogiannis et al. 2019, generally present a weaker flow in Sout Evoikos Gulf, especially at its northern segment. The arrows in figure 11 represent the general direction NW-N trend of the strongest vectors presented in the specific work.
I suggest acceptance after minor revisions.
Response: Thank you for your constructive comments and recommendation for acceptance after minor revisions.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper reports the surface sediment distribution around Evia Island, Greece, and try to discuss the net sediment transport in this area inferred from spatial pattern of grain-size trends and further the relationship with oceanographic conditions such as water circulations. Data looks fine and original, and discussions are interesting. However, I have a major concern on the current manuscript.
Major concern:
I basically can accept the idea on estimation of net sediment transport paths from spatial pattern of grain-size trends. However, for utilization of the idea, I believe there are some necessary conditions. Most of the previous studies using this method have been conducted for silici-clastic sediments under river, beach and tidal environments. From the current manuscript, at least some parts of the surface sediment samples belong to so-called “mixed sediment”, which is the mixture of silici-clastic and bio-clastic grains. Controlling factors of grain-size of bio-clastic grains are so variable, such type and size of the original shell, post-depositional physical destruction and chemical dissolution, durability for physical destruction controlled by minerals, structures and thickness of shell and so on. This means that controlling factors of spatial distribution of the bio-clastic grains are not simple and are more complicated than those of the silici-clastic grains. My fundamental question is; grain-size changing pattern of the bio-clastic materials is the same as that of the silici-clastic materials or not. If no, we can’t use the trend analysis for the bio-clastic sediments. If yes, we may use the trend analysis for the pure bio-clastic sediments. However, it is still unclear that we can use the trend analysis for the “mixed” sediments. Strength of the grains and broken pattern (or fining trend) may also be different between silici-clastic and bio-clastic grains. Therefore, it is really doubtful as to applicability of the trend analysis for the “mixed” sediments. A previous study removed carbonate materials from their sediments, conducted mechanical analysis and applied the trend analysis to estimate net transport trends (e.g., Liang et al., 2020). This may be a good way to avoid the complicated and unresolved problem.
These issues should be shown in Introduction and also better to be discussed in text.
Minor concerns:
Description of the analytical methodology is insufficient. More detailed methodology on sediment sampling, pre-preparation and grain-size analysis should be described. For example, how thick surface sediments are taken for the analysis? We usually found the lithological difference even in the uppermost 10 cm interval of surface sediments. The authors observed sediment lithology of surface sediments before taking subsamples for the analysis?
Some of the figures are not informative. I am not familiar with Aegean Sea, so it is difficult to find the local place names. But I can’t find location of each local place name in the figures easily. Size and color of the letter the authors used in each figure (such as the local place names, water depths and any other numerals is not good for easier understanding for the readers. These should be changed.
General explanation on water circulation, wave and tidal conditions and location and discharge of major rivers in and around the study area should be added in Section 2.1. Also, please indicate an index map indicating regional tectonic framework and major faults in Figure 1.
Many interpretations are described in Results section. These should be deleted and moved to Discussion.
It is difficult to understand the exact locations the authors indicate in text. For example, in L. 264, the authors wrote “in the southern part of the easternmost Evia coast”. However, I have no idea where that is referring to. Where is the Evia coast? Also in L. 269, the authors wrote “southwards of Kymi a SE net sediment transport is dominant”. If the location is along the coast ~20-30 km south from Kymi, it is OK. But this explanation is quite difficult to understand easily. These are only examples that the current manuscript is not “Readers friendly”. Please check the full manuscript again and make adequate corrections for creating more “readers friendly” manuscript.
I am a bit confusing due to some discordant statements in text with the results shown in figures. For example, in L. 260, the authors wrote “in Petalioi Gulf, sediment transport is predominantly directed toward the southwest”. However, in Figure 7, calculated net transport vectors in Petalioi Gulf show northward transport, which may be supported by surface water circulation in the gulf (Figure 11). There are several mismatches between descriptions in text and vectors in Figure 7. Please check again.
What is X and Y in Table 1? If these indicate coordinates of the sampling location, the coordinates should be shown in Latitude and Longitude.
Author Response
Response to reviewer 2 comments
We sincerely appreciate your constructive comments. Please find below our responses and the revisions we have made to the manuscript in accordance with your suggestions.
Major concern:
I basically can accept the idea on estimation of net sediment transport paths from spatial pattern of grain-size trends. However, for utilization of the idea, I believe there are some necessary conditions. Most of the previous studies using this method have been conducted for silici-clastic sediments under river, beach and tidal environments. From the current manuscript, at least some parts of the surface sediment samples belong to so-called “mixed sediment”, which is the mixture of silici-clastic and bio-clastic grains. Controlling factors of grain-size of bio-clastic grains are so variable, such type and size of the original shell, post-depositional physical destruction and chemical dissolution, durability for physical destruction controlled by minerals, structures and thickness of shell and so on. This means that controlling factors of spatial distribution of the bio-clastic grains are not simple and are more complicated than those of the silici-clastic grains. My fundamental question is; grain-size changing pattern of the bio-clastic materials is the same as that of the silici-clastic materials or not. If no, we can’t use the trend analysis for the bio-clastic sediments. If yes, we may use the trend analysis for the pure bio-clastic sediments. However, it is still unclear that we can use the trend analysis for the “mixed” sediments. Strength of the grains and broken pattern (or fining trend) may also be different between silici-clastic and bio-clastic grains. Therefore, it is really doubtful as to applicability of the trend analysis for the “mixed” sediments. A previous study removed carbonate materials from their sediments, conducted mechanical analysis and applied the trend analysis to estimate net transport trends (e.g., Liang et al., 2020). This may be a good way to avoid the complicated and unresolved problem.
These issues should be shown in Introduction and also better to be discussed in text.
Response: The bioclastic grains as evidenced by the stereoscopic analysis in progress constitute a negligible percentage of the sample mass. Of course, there were 4-5 instances, where pure biogenic samples consisting of large-scale shells have been acquired. These samples have been excluded from the analysis. The sampling effort and laboratory testing section has been updated to include this approach (“ Physical samples, collected using grab sampling methods of the top layer of sediment (up to 5cm), adhered to the HSGME Marine Geology Laboratory standards, and all samples were analyzed in the laboratory following international protocols [23]. Samples that were consisting by purely biogenic constituents (mainly shells in shallow waters close to the shoreline) were excluded from the analysis”).
Minor concerns:
Description of the analytical methodology is insufficient. More detailed methodology on sediment sampling, pre-preparation and grain-size analysis should be described. For example, how thick surface sediments are taken for the analysis? We usually found the lithological difference even in the uppermost 10 cm interval of surface sediments. The authors observed sediment lithology of surface sediments before taking subsamples for the analysis?
Response: The analysis was performed at the top 3-5cm of the sediment cover as acquired by the grab sampler used for the specific task. The samples are treated in terms of grain size analysis following the common practices as described by the relevant references [23]
Some of the figures are not informative. I am not familiar with Aegean Sea, so it is difficult to find the local place names. But I can’t find location of each local place name in the figures easily. Size and color of the letter the authors used in each figure (such as the local place names, water depths and any other numerals is not good for easier understanding for the readers. These should be changed.
Response: Figures have been updated with increased text size. Figure 1 has been revised so that it is easier for the reader to follow the areas described in the text.
General explanation on water circulation, wave and tidal conditions and location and discharge of major rivers in and around the study area should be added in Section 2.1. Also, please indicate an index map indicating regional tectonic framework and major faults in Figure 1.
Response: Figure 1 has been updated to display the major tectonic features of the Aegean. The general circulation pattern of the Aegean has been described in detail section 4.1 and in detail for the study area in section 4.2. A new figure has been added (Figure 11) where the Aegean Sea circulation pattern is displayed. Additionally in figure 11 (renamed in the revised manuscript to figure 12) the hydrographic network has been presented in order to be assessed with the sediment transport vectors.
Many interpretations are described in Results section. These should be deleted and moved to Discussion.
Response: Interpretations from the results section has been removed.
It is difficult to understand the exact locations the authors indicate in text. For example, in L. 264, the authors wrote “in the southern part of the easternmost Evia coast”. However, I have no idea where that is referring to. Where is the Evia coast? Also in L. 269, the authors wrote “southwards of Kymi a SE net sediment transport is dominant”. If the location is along the coast ~20-30 km south from Kymi, it is OK. But this explanation is quite difficult to understand easily. These are only examples that the current manuscript is not “Readers friendly”. Please check the full manuscript again and make adequate corrections for creating more “readers friendly” manuscript.
Response: Figures and text have been updated to be more user friendly. For example, the text starting in line 264 has been rephrased as follows: “In the southern part of the easternmost Evia coast, near Kafireas cape (Figure 7), sediment transport shows a northward transport, oriented vertically to the coastline, indicating that materials are being carried southward towards the open Aegean Sea.’ Kafireas cape is clearly shown if Figure 7. Additionally, all maps have been updated so that Euboean gulf is stated as Evoikos Gulf to be consistent with the manuscript. Additionally, line 269 has been rewritten as following: “Southwards of Kymi, at the southern end of Kymi bay (Figure 7), a SE net sediment transport is dominant”.
Figure 7 has been updated including the new names that would help the reader to follow better the analysis.
I am a bit confusing due to some discordant statements in text with the results shown in figures. For example, in L. 260, the authors wrote “in Petalioi Gulf, sediment transport is predominantly directed toward the southwest”. However, in Figure 7, calculated net transport vectors in Petalioi Gulf show northward transport, which may be supported by surface water circulation in the gulf (Figure 11). There are several mismatches between descriptions in text and vectors in Figure 7. Please check again.
Response: The comment is right to the point, there where many typos in the text which resulted in mismatches, confusing the reader. Following the recommendation of all reviewers these mismatches have been corrected. For example, line 260 (261 in the revised manuscript) has been rewritten as follows: In Petalioi Gulf, sediment transport is predominantly directed toward the northwest.
What is X and Y in Table 1? If these indicate coordinates of the sampling location, the coordinates should be shown in Latitude and Longitude.
Response: The maps are presented in geographic coordinates (Lat, Lon) (WGS84) in order to be easier for the reader to located the described regions. The sampling points introduced for the net transport vectors analysis follow a projected system in meters (WGS UTM34N and 35N, EPGS32634 and 32635 respectively)
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsI thank the authors to revise original manuscript according to my comments. I recognize that the authors revised the manuscript adequately for some comments of mine. However, some revisions are insufficient. I should point out some major and minor comments, which should be corrected before publication, for the revised manuscript as follows.
Major concerns:
Sediment compositions: I check the revision. I understand that the authors exclude pure biogenic sediments from their analysis. However, the biogenic materials are also included in the “mixed” sediments, which compose of siliciclastic and bioclastic materials. Based on classical IODP classification, ratio of siliciclastic and bioclastic ranges from 4:6 to 6:4. I understand that most of sediments used in this study may be siliciclastic sediments. But even content of bioclastic is low, changing trend of sediment grain-size may be influenced by sediment compositions. Furthermore, even for the siliciclastic sediments, heavy mineral grains may have different mode on sediment transport from light mineral grains. Therefore, the authors should add some explanations on the influence or limitation of sediment compositions for this methodology. This addition may increase scientific value of this paper.
Description of the analytical methodology: I still feel that description of the analytical methodology is insufficient. Methodology described by Folk (1980) is one of the standard methods for sediment grain-size analysis but is not an international protocol. There are so many methods for grain-size analysis of sediment, some of which are new and the others are traditional. But without the detailed description of methodology, it is difficult to expand this methodology in future.
Descriptions on water circulations, wave and tides and discharges from major rivers: I understand that most of these are described in sections 4.1, 4.2 and 4.3 in “Discussion”. However, all descriptions in sections 4.1 and 4.2 are NOT the results from this study, but a summary of the previous studies. This means that these are NOT “Discussion”. These contents with some descriptions on discharges from rivers in section 4.3 (e.g., L. 436, 442-443, 446-447) should be moved to the descriptions of the study area (section 2.1). Also, water circulations in Figures 11 and 12 and major rivers in Figure 12 should be moved to Figure 1 or new Figure 2. Without this movement, some interpretations on the influences of these mentioned in “Results” (e.g., L. 222-223, the others are shown in minor comments) are difficult to follow.
Minor comments:
L. 110: Where is “Cyclades Archipelago”? Please indicate in Figure 1.
L. 112: Where is “Saroic Gulf”? Please indicate in Figure 1.
L. 112-113: Need citation of “glacial sea levels of this area”
L. 116: Where is “Cavo Doro Strait” and “Andros”? Please indicate in Figure 1.
L. 128: Where is “North Evoikos Gulf”? Please indicate in Figure 1.
L.130-132: This sentence is NOT related to “Sampling”. Please delete.
L. 139-141: Thank you for your addition of this sentence. However, I think more clear indication that all sediments used for this study are composed of siliciclastic grains are needed.
L. 180, 226: “sediment composition” should be “grain-size composition”.
L. 187-189: This statement a bit contradicts that on L. 139-141.
Sections 3.2 and 3.3: Distributions on some parameters are NOT described adequately as follows.
L. 216-223: Why there is no description on two locations with better sorting values (<1), which find in the Aegean Sea of Figure 6?
L. 220-221: I can’t find area of the better sorting around Chalkis in Figure 5b.
L. 224-231: Why there is no description on locations with low skewness values (<-0.3), which find in both areas of Figure 6?
L. 268-269: I can’t find bidirectional transport at the central part of South Evoikos Gulf. Vectors in this part are small and directions are NOT bidirectional but multidirectional and no preferred direction.
L. 271: “northwest” is “north”?
Sections 3.2 and 3.3: There are many interpretations in this section as shown below. This is “Results” chapter. To avoid making confusions or misunderstanding for the readers, these interpretations should be deleted.
L. 222-223: “which could be..... waves or currents” is interpretation without any evidence and discussion and NOT result.
L. 231: “likely due to..... in these areas” is interpretation without any evidence and discussion and NOT result.
L. 237-238: “indicating a tendency..... coastal inputs” is interpretation without any evidence and discussion and NOT result.
L. 282-283: “This eastward flow..... away from the shore” is interpretation without any evidence and discussion and NOT result.
L. 285-286: “and probably..... of this region” is interpretation without any evidence and discussion and NOT result.
L. 291-293: “Overall,..... Aegean regions” is interpretation without any evidence and discussion and NOT result.
L. 274: Where is “Attica Peninsula”? Please indicate in Figure 1.
L. 279: Please consider to delete “indicating that materials are being carried southward”
L. 301: Where is “Evoikos Sea”? Please indicate in Figure 1.
L. 319, 320, 329, 338, 342, 347: Where is “Evoikos Gulf”? Is this combination of North and South Evoilos gulfs? If so, please change “Evoikos gulf” to “North and South Evoikos gulfs”.
L. 406: Where is “Euripus Strait”? Please indicate in Figure 1.
L. 438-439: Amounts of water discharge are different from those of sediment discharge. These have no simple linear relationship. Statement of this sentence is too simplified. Please rewrite.
L. 467: Where is “Euripus channel”? Please indicate in Figure 1. Is this the same as “Euripus Strait” in L. 406? If so, please use a single term.
Table 1: I still can’t understand what is X and Y. Need explanation in Table caption.
Figure 1: It is difficult to read some local place names in Figure 1. This should be corrected.
Figure 6 b: What is a gray dot in Figure 6b?
Author Response
Response to reviewer 2 comments
We sincerely appreciate your constructive comments. Please find below our responses and the revisions we have made to the manuscript in accordance with your suggestions.
Major concern:
COMMENT: Sediment compositions: I check the revision. I understand that the authors exclude pure biogenic sediments from their analysis. However, the biogenic materials are also included in the “mixed” sediments, which compose of siliciclastic and bioclastic materials. Based on classical IODP classification, ratio of siliciclastic and bioclastic ranges from 4:6 to 6:4. I understand that most of sediments used in this study may be siliciclastic sediments. But even content of bioclastic is low, changing trend of sediment grain-size may be influenced by sediment compositions. Furthermore, even for the siliciclastic sediments, heavy mineral grains may have different mode on sediment transport from light mineral grains. Therefore, the authors should add some explanations on the influence or limitation of sediment compositions for this methodology. This addition may increase scientific value of this paper.
REPSONSE: The limitations you refer to are absolutely reasonable. For this reason, a very extended analysis of the statistical significance of the results is presented in the manuscript (lines 300-352, 473-491). The statistical test answers to a simple question: is the calculated vector significant or it cannot be recognized among the noise that all of the parameters that you refer to may contribute (mineral composition, biogenic clast showing a different hydraulic behavior etc). The statistical tests try to overcome the limitation introduced by the various types of grain heterogeneities you refer to, and to provide a degree of confidence for further application of the methodology. Additionally, it is also important to understand that the grain size parameters used for the analysis reflect between other factors (hydrodynamic conditions for example) the variability on sediment compositions. This is the advantage of the specific method and this is why it is widely applied in similar studies.
McLaren (1981) who was of the first to introduce the analysis of grain size trends, identified that the grain size characteristics of a sedimentary deposit are dependent on sedimentary processes as defined by i) winnowing, ii) selective deposition from sediment in transport, and iii) total deposition of sediment in transport; and the characteristics of its source deposit. This implies that as described before grain size properties including grain-size parameters reflect many of the factors like hydrodynamic conditions and variations in grain size composition. He has also addressed exceptions that have to be considered like clay particles flocculation of involvement of various sediment sources.
Gao and Collins (1992) applied their methodology in a mixed system where sediment supply is derived from coastal erosion, river inputs, while unknown amount a detrital grain is derived from reworking of the inner continental shelf sediments. Additionally, coral reefs provided about 20% of grains in the study.
The same approach is followed in many other studies various settings (e.g.: Gao and Collins, 1994; Pedreros et al., 1996; Asselman, 1999; Duman et al., 2006; Poizot et al., 2008; Carriquiry and Sánchez, 1999; Carriquiry et al., 2001, Liang et al., 2019).
In order to explicitly address the issues that you have pointed out, a paragraph has been added to the manuscript stating the following:
The value of the method is that grain-size parameters reflect the various factors that conntrol the transport patterns of sediments. Such factor is the grain-size composition, the presence of single or multiple sediment sources, the hydrodynamic conditions, the trend of finer material to flocculate. It is characteristic that the area where Gao and Collins (1992) applied the method was a mixed system where sediment supply is derived from coastal erosion, river inputs, while unknown amount a detrital grain is derived from re-working of the inner continental shelf sediments. Additionally, coral reefs provided about 20% of grains in the study. The limitation of the method in very complex settings where multiple sediment sources may occur and hydrodynamic behavior of the grains is affected by the nature of sediment sources (e.g. the settling velocity of skeletal carbonate grains is shape – depenedent, Slootman et al., 2023) is partially smoothed by the application of statistical significance tests where net transport vectors that are distinguished form the potential noise that all the uncertainties can introduce.
COMMENT: Description of the analytical methodology: I still feel that description of the analytical methodology is insufficient. Methodology described by Folk (1980) is one of the standard methods for sediment grain-size analysis but is not an international protocol. There are so many methods for grain-size analysis of sediment, some of which are new and the others are traditional. But without the detailed description of methodology, it is difficult to expand this methodology in future.
REPSONSE: The term protocol should not be confused with the term standard. The procedure regarding grain size analysis as described by Folk is definitely a scientific protocol (A detailed plan of a scientific or medical experiment, treatment, or procedure). It is not of course a testing standard, but it has been the base for standard test methods (BS.1377 part 2, 9.2 Wet sieving method and 9.4 Sedimentation by the pipette method). In order to avoid this misunderstanding, the term protocol has been removed and a brief analysis of the test method has been provided.
The granulometric analysis is conducted using the method of Folk (1974, 1980). According to this method, the sediment is divided into fractions (parts) based on grain diameter per 1Φ, and the weight of each fraction is then determined. Initially, any pebbles or shells with dimensions significantly different from the rest of the sediment are removed to prevent distortion of the granulometric analysis results. Subsequently, the fractions are separated: coarse materials (gravels and sands) are processed using the sieving method, while fine-grained materials (silts and clays) are processed using the pipette method, as follows: First, a small representative quantity of the sample (20–30 g) is taken and dissolved in 50–100 cm³ of distilled water. Gradually, 20–30 cm³ of Hâ‚‚Oâ‚‚ (50% hydrogen peroxide) is added to oxidize any organic matter present in the sediment. After 24 hours, particularly for samples containing the finer fractions (silts and clays), approximately 15–20 ml of NH₃ (10% ammonia) is added as a dispersing agent to prevent clay flocculation. After thorough stirring, the suspension is poured through a sieve with a mesh opening diameter of 4Φ (0.063 mm). This value represents the boundary between sand and fine-grained materials (silts and clays). The sediment retained in this sieve, comprising the total coarse materials, is washed with distilled water, placed in a crucible, and dried at 80°C. After drying, the total sand fraction is further separated into sub-fractions using a shaker and a series of sieves with mesh opening diameters of: -1Φ (2 mm), 0Φ (1 mm), 1Φ (0.500 mm), 2Φ (0.250 mm), 3Φ (0.125 mm), and 4Φ (0.063 mm). All weight measurements are performed with an accuracy of four decimal places. The suspension that passes through the 4Φ sieve is placed in a 1-liter graduated cylinder, which is then filled with distilled water to a total volume of one liter. The contents of the cylinder are homogenized with vigorous stirring, and immediately after, 20 cm³ samples of the suspension are taken at regular time intervals and from specific depths relative to the zero mark of the graduated cylinder, as follows: At 20 seconds from a depth of 20 cm, at 1 minute 45 seconds, 6 minutes 58 seconds, 28 minutes, 1 hour 51 minutes from a depth of 10 cm, and at 3 hours 42 minutes from a depth of 5 cm.
The temperature of the solution during sampling is maintained at 25°C by placing the graduated cylinders in a constant-temperature water bath. The sampled material is then placed in crucibles, dried at 80°C, and weighed with an accuracy of four decimal places.
COMMENT: Descriptions on water circulations, wave and tides and discharges from major rivers: I understand that most of these are described in sections 4.1, 4.2 and 4.3 in “Discussion”. However, all descriptions in sections 4.1 and 4.2 are NOT the results from this study, but a summary of the previous studies. This means that these are NOT “Discussion”. These contents with some descriptions on discharges from rivers in section 4.3 (e.g., L. 436, 442-443, 446-447) should be moved to the descriptions of the study area (section 2.1). Also, water circulations in Figures 11 and 12 and major rivers in Figure 12 should be moved to Figure 1 or new Figure 2. Without this movement, some interpretations on the influences of these mentioned in “Results” (e.g., L. 222-223, the others are shown in minor comments) are difficult to follow.
The manuscript has been reformed by moving the water circulation information in section 2.1. Figure 11 has also been removed in section 2.1 and referred as figure 2 following your suggestion where the general circulation pattern of the Aegean is presented, while a new figure (Figure 3 in the revised manuscript) shows the water circulation patterns in the study area.
Minor comments:
COMMENT: L. 110: Where is “Cyclades Archipelago”? Please indicate in Figure 1.
REPSONSE: Has been rewritten in consistency with figure 1: To the south, the Cyclades area in the central Aegean forms an isolated plateau (Cyclades plateau, Fig. 1) with numerous islands
COMMENT: L. 112: Where is “Saroic Gulf”? Please indicate in Figure 1.
REPSONSE:
COMMENT: L. 112-113: Need citation of “glacial sea levels of this area”
REPSONSE: The reference has been added
COMMENT: L. 116: Where is “Cavo Doro Strait” and “Andros”? Please indicate in Figure 1.
REPSONSE: Cavo Doro strait and Andros were indicated in figure 1. We have increased the text size to be legible.
COMMENT: L. 128: Where is “North Evoikos Gulf”? Please indicate in Figure 1.
REPSONSE: See previous comment.
COMMENT: L.130-132: This sentence is NOT related to “Sampling”. Please delete.
REPSONSE: Lines 130-132 have been deleted.
COMMENT: L. 139-141: Thank you for your addition of this sentence. However, I think more clear indication that all sediments used for this study are composed of siliciclastic grains are needed.
REPSONSE: See the reply on the first major comment
COMMENT: L. 180, 226: “sediment composition” should be “grain-size composition”.
REPSONSE: It has been corrected in both lines
COMMENT: 187-189: This statement a bit contradicts that on L. 139-141.
REPSONSE: It is referred to reworked clasts of skeletal grains. The case in lines 139-141 refers to large sized (more than 2mm) well preserved shells. The text has been so that there is no misunderstanding: “Here, the sediment becomes predominantly composed of sandy calcareous skeletal fragments and clasts, primarily consisting from reworked remnants of benthic and planktonic organisms, which contribute to a more heterogeneous texture as sand fractions diminish.”
Sections 3.2 and 3.3: Distributions on some parameters are NOT described adequately as follows.
COMMENT: L. 216-223: Why there is no description on two locations with better sorting values (<1), which find in the Aegean Sea of Figure 6?
REPSONSE: The text has been revised as following: It two cases as shown in figure 8 moderately sorted samples occur, suggesting probably local hydrodynamic conditions that favor extended sediment reworking.
COMMENT: L. 220-221: I can’t find area of the better sorting around Chalkis in Figure 5b.
REPSONSE: The text has been revised as following: “Better sorting (1-2φ) is observed in a restricted area on the southeastern margin of South Evoikos, as well as in the area between south Evia and Skyros island.”
COMMENT: L. 224-231: Why there is no description on locations with low skewness values (<-0.3), which find in both areas of Figure 6?
REPSONSE: The text has been revised as following: “Locally, in both areas samples with skewness <-0.3 occur (Fig. 8) located mainly near the coasts, indicating probably high energy conditions.” It has to mentioned here that where samples showing a specific character are isolated cannot consist a mappable entity like those presented in the updated figs. 6 and 7.
COMMENT: L. 268-269: I can’t find bidirectional transport at the central part of South Evoikos Gulf. Vectors in this part are small and directions are NOT bidirectional but multidirectional and no preferred direction.
REPSONSE: Has been replaced by multidirectional.
COMMENT: L. 271: “northwest” is “north”?
REPSONSE: Has been corrected to “north”
Sections 3.2 and 3.3: There are many interpretations in this section as shown below. This is “Results” chapter. To avoid making confusions or misunderstanding for the readers, these interpretations should be deleted.
COMMENT: L. 222-223: “which could be..... waves or currents” is interpretation without any evidence and discussion and NOT result.
REPSONSE: Lines 222-223 have been deleted.
COMMENT: L. 231: “likely due to..... in these areas” is interpretation without any evidence and discussion and NOT result.
REPSONSE: Line 231 has been deleted.
COMMENT: L. 237-238: “indicating a tendency..... coastal inputs” is interpretation without any evidence and discussion and NOT result.
REPSONSE: Lines 237-238 have been deleted
COMMENT: L. 282-283: “This eastward flow..... away from the shore” is interpretation without any evidence and discussion and NOT result.
REPSONSE: Lines 282-283 have been deleted
COMMENT: L. 285-286: “and probably..... of this region” is interpretation without any evidence and discussion and NOT result.
REPSONSE: Lines 285-286 have been deleted
COMMENT: L. 291-293: “Overall,..... Aegean regions” is interpretation without any evidence and discussion and NOT result.
REPSONSE: Lines 291-293 have been deleted
COMMENT: L. 274: Where is “Attica Peninsula”? Please indicate in Figure 1.
REPSONSE: Indicated
COMMENT: L. 279: Please consider to delete “indicating that materials are being carried southward”
REPSONSE: Deleted
COMMENT: L. 301: Where is “Evoikos Sea”? Please indicate in Figure 1.
REPSONSE: The text has been revised as following: (Evoikos sea consisting of North, South Evoikos and Petalioi Gulfs and Aegean sea)
COMMENT: L. 319, 320, 329, 338, 342, 347: Where is “Evoikos Gulf”? Is this combination of North and South Evoilos gulfs? If so, please change “Evoikos gulf” to “North and South Evoikos gulfs”.
REPSONSE: North, South Evoikos and Petalioi gulfs have been rewritten in accordance with the correction following your previous comment as Evoikos Sea.
COMMENT: L. 406: Where is “Euripus Strait”? Please indicate in Figure 1.
REPSONSE: Corrected.
COMMENT: L. 438-439: Amounts of water discharge are different from those of sediment discharge. These have no simple linear relationship. Statement of this sentence is too simplified. Please rewrite.
REPSONSE: The text has been modified as following: This riverine input could be potentially marked by the prevalence of finer sediments in these specific areas, though data regarding the amount of sediment discharge are not available.
COMMENT: L. 467: Where is “Euripus channel”? Please indicate in Figure 1. Is this the same as “Euripus Strait” in L. 406? If so, please use a single term.
REPSONSE: Has been rewritten as Euripus strait to be consistent with the rest of the text.
COMMENT: Table 1: I still can’t understand what is X and Y. Need explanation in Table caption.
REPSONSE: Table caption has been updated to have a clear reference in the applied X and Y coordinates represent sampling locations in UTM34N projection system.
COMMENT: Figure 1: It is difficult to read some local place names in Figure 1. This should be corrected.
REPSONSE: Text size has been increased in Figure 1 so that local names are more legible.
COMMENT: Figure 6 b: What is a gray dot in Figure 6b?
REPSONSE: The gray dot represents samples that do not constitute a mappable entity. Figure caption has been revised to address the issue.
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
Thank you for revising your manuscript. I read carefully, and recognized adequate corrections according to my previous comments. Only a very minor issues are; section numbers should be corrected in L. 139 and L. 164, and some references look incomplete, e.g., no book information for Middleton and Hampton, 1973 and so on. Please check all references again.
Author Response
Dear reviewer,
Thank you for your prompt reply and comments. We have revised the manuscript following your suggestions.
Comment 1: Section numbers should be corrected in L. 139 and L. 164
Response: Section numbers corrected
Comment 2: Some references look incomplete, e.g., no book information for Middleton and Hampton, 1973 and so on. Please check all references again.
Response: The specific reference has been corrected, along with other references and a duplicate reference.
