Annual Dynamics of a Layered Phytoplankton Structure in a Meromictic Lagoon Partially Isolated from the White Sea

Round 1

Reviewer 1 Report

 Consider:  If the chemocline co-occurs with one of the pycnoclines  - it’s worth mentioning.

 29

The phytoplankton structure and dynamics in the Lagoon and the sea by 24.5% was

I don’t know what this percent means

 

89  there only one research of seasonal

Change to: there is only one study of

Whale Premium Submersible Pump GP1352 (USA) and 157

Use a peristaltic pump not an impeller pump to minimize damage to plankton

 

To count cells in the counting chamber, water samples were concentrated by reverse 171 filtration technique

Cite Dodson and Thomas?

only salinity determines the structure of the PhP in the Lagoon. The 713

Maybe you should say correlates vs determines. Maybe an unmeasured parameter that correlates with salinity and affects the PhP.

 

During the growing season the 727 oxygen content in water declined with increase in the BC, both auto- and heterotrophic. 728

Oxygen content declines with increasing temperature too. If the percent oxygen saturation declines with autotrophic biomass, that’s quite a heterotrophic system.

7 of the 8 studied parameters (salinity, air 785 temperature, concentration of dissolved O2, pH, ORP, daylight, depth) determined (or 786 were determined by) the dynamics of PhP i

when you say certain parameters determine or are determined by, that is correlation. All you can say and It would be good to know if the correlations are positive or negative. Other studies may have found correlations and determined the mechanisms for causes, that would be good to mention if so. If you think that salinity causes changes in the plankton, you could cite that rationale (salinity optima or salinity vs growth curves of particular species, e.g.)

 

 

Daylength seems

The daylight seems to be the crucial factor of the seasonal PhP dynamics in the semi-iso-794 lated coastal stratified lakes and lagoons. 795

You mention that the Lagoon phytoplankton biomass may be controlled partly by upwelling, but maybe also by inflows from land. To what degree are the plankton in the upper layers nutrient limited? Is the nutrient limitation partly ameliorated during the periods when the lagoon biomass is higher than the that in the adjacent sea. Maybe mention how the biomass compares to similar systems that are less nutrient limited and that experience more blooms. Maybe estimate the net primary production based on percent oxygen saturation.

 

Does the weather, especially wind, correlate with biomass changes? That may point to a nutrient supply effect. The biomass being highest in the chemocline indicates that is the main nutrient source.

I don’t see much evidence that you are interested in the drivers for the plankton biomass and  dynamics, which are something some readers would be interested in.

Your paper has multiple grammar errors, which sometimes makes it hard to understand. I imagine there is an English scientific writing editor you could have read it over.

Author Response

Dear colleague! It was nice to read your review. Many thanks for the corrections and informative suggestions. We tried to take into account all the comments.

Reviewer's note:  Consider:  If the chemocline co-occurs with one of the pycnoclines  - it’s worth mentioning. 29

Reply: On the page 4, line 151-152 we indicated what we mean by “chemocline”: “…the chemocline (boundary of the anaerobic zone), which in different months was located 151 a little differently between the horizons of 4.5 m and 5.4 m”. More, in “Discussion” section we summarize water column zonation and refine that during the year of our study there was halocline at a depth of 1-2 m, and what we call chemocline at a depth range of 4.5−5.5.  Calling the jump in salinity a halocline, we give a more precise definition, since the "pycnocline" can be caused not only by water mineralization, but also by temperature. The peculiarity of the studied lagoon is two pycnoclines (one at a depth of 1-2 m and the second at 4.5-5.5 m), but only the second one coincides with the chemocline. To avoid confusion, we clarify that:

“…2) a layer at a depth of 1−2 m is a halocline; … 4) in the depth range of 4.5−5.5 m the boundary of the anaerobic zone (chemocline) is observed. Chemocline is characterized by steep gradients in a variety of hydrological parameters, including salinity, temperature, oxygen concentration, ORP, pH…”

According to the phytoplankton structure, the upper pycnocline is important as a halocline, since it separates layers with different salinity and expected species adapted to different salinity ranges. And the second one separates the zone suitable for phytoplankton from the unsuitable anaerobic one, so in this case it is more important that it is a chemocline (a jump not only in salinity and temperature, but also redox interface).

Reviewer's note: The phytoplankton structure and dynamics in the Lagoon and the sea by 24.5% was

I don’t know what this percent means

Reply: According to DistLM phytoplankton structure and dynamics by 24.5% were related to the daylight, water salinity, oxygen content and pH, They didn’t depend on water T, underwater illuminance, and depth..  To make it clearer, we added:

According to sequential tests DistLM phytoplankton structure and dynamics in the Lagoon and in the sea by 24.5% were related to the daylight, water salinity…

Reviewer's note: 89  there only one research of seasonal

Change to: there is only one study of

Reply: Thank you. Corrected.

Reviewer's note:  Whale Premium Submersible Pump GP1352 (USA) and 157

Use a peristaltic pump not an impeller pump to minimize damage to plankton

 Reply: Thank you. You're right. Your advice has been accepted. In this study, we were guided by our own observations that sampling with impeller pump is not suitable only for large objects (for example, jellyfish, filamentous algae with long thalloms). However, the Copepods, and even the soft-bodied polychaete larvae, pass through alive and unharmed. Moreover, microscopic organisms, including phytoplankton, do not suffer. Anyway thanks you for the advice.

Reviewer's note:   To count cells in the counting chamber, water samples were concentrated by reverse 171 filtration technique

Cite Dodson and Thomas?

Reply: Thank you. We added the reference (Sournia, A. (Ed.), 1978) to the text as well as to the reference list.

To count cells in the counting chamber, water samples were concentrated by reverse filtration technique using nuclear track membrane filters (Dubna, Russia) with a pore diameter of 4–5 μm, and settling method (Sournia, 1978; Vinogradov, 1983 – [47,48].

Sournia, A. (Ed.), 1978. Phytoplankton Manual. Monographs on Oceanographic Methodology, 1978, vol. 6. UNESCO, Paris, 337 p.

Reviewer's note:   only salinity determines the structure of the PhP in the Lagoon. The 713

Maybe you should say correlates vs determines. Maybe an unmeasured parameter that correlates with salinity and affects the PhP.

 Reply: Thank you. We agree. Corrected sentence:

Among three factors that were important in Lake Kislo-Sladkoe (temperature, salinity and illumination), only salinity correlates with the structure of the PhP in the Lagoon.

Reviewer's note:    During the growing season the 727 oxygen content in water declined with increase in the BC, both auto- and heterotrophic. 728

Oxygen content declines with increasing temperature too. If the percent oxygen saturation declines with autotrophic biomass, that’s quite a heterotrophic system.

Reply: In our case biomass doesn’t follow temperature directly. Two biomass picks are in the mid-August against the backdrop of a drop in water temperature, and in the beginning of September by continued decrease of water temperature. We agree with you mention about heterotrophic statue. For this reason, we have further specified:

Additionally, an increase in the total PhP biomass contributes to an increase in the intensity of the microbial loop and an increase in oxygen consumption for bacterial respiration and organic oxidation.

Reviewer's note:   7 of the 8 studied parameters (salinity, air 785 temperature, concentration of dissolved O2, pH, ORP, daylight, depth) determined (or 786 were determined by) the dynamics of PhP i

when you say certain parameters determine or are determined by, that is correlation. All you can say and It would be good to know if the correlations are positive or negative. Other studies may have found correlations and determined the mechanisms for causes, that would be good to mention if so. 

Reply:  The answer is given in the figure - positive or negative correlation. Here we focus on the statistical significance of the correlation. We changed the sentence.

According to the marginal tests DistLM 7 of the 8 studied parameters (salinity, air temperature, concentration of dissolved O₂, pH, ORP, daylight, depth) correlated with the dynamics of PhP in the Lagoon as well as in the sea statistically significantly…

Reviewer's note:    If you think that salinity causes changes in the plankton, you could cite that rationale (salinity optima or salinity vs growth curves of particular species, e.g.)

Reply: There are no such data for our species. Phytoplankton species are very tolerant of changes in salinity and can survive over a wide range. In cultures, we provided such measurements, but in nature other factors are involved - competition with other species, the presence of nutrients and their ratio.

Reviewer's note:    Daylength seems

The daylight seems to be the crucial factor of the seasonal PhP dynamics in the semi-iso-794 lated coastal stratified lakes and lagoons. 795

You mention that the Lagoon phytoplankton biomass may be controlled partly by upwelling, but maybe also by inflows from land. To what degree are the plankton in the upper layers nutrient limited? Is the nutrient limitation partly ameliorated during the periods when the lagoon biomass is higher than the that in the adjacent sea. Maybe mention how the biomass compares to similar systems that are less nutrient limited and that experience more blooms. Maybe estimate the net primary production based on percent oxygen saturation.

Reply: Our work is just a first assessment, an exploratory one. We only tested easily detectible factors. Their contribution to the PhP dynamics is only 24.5%. In future, we propose to check other factors.

Reviewer's note:     Does the weather, especially wind, correlate with biomass changes? That may point to a nutrient supply effect. The biomass being highest in the chemocline indicates that is the main nutrient source.

Reply: Thank you for the question. If wind mixing could affect the water column, the lagoon would not be meromictic - According to the definition of a meromixis, a meromictic lake is a lake which has layers of water that do not intermix, See lines 54-55: “In the course of increasing isolation from the sea, the reservoir can pass through the meromictic stage with vertical stratification that persists year after year for a long time [3].

3. Hakala, A. Meromixis as a part of lake evolution – observations and a revised classification of true meromictic lakes in Finland, 811 Boreal Environ. Res., 2004, vol. 9: 37–53.

Salinity serves as an indicator of mixed layer thickness. Surface layer of 0-0.5 m is clearly subject to wind mixing, because its salinity is less than in the rest of water column. This is what makes meromictic water bodies especially interesting: the flow of organic matter is directed downward to the anaerobic zone where it is buried for many years, centuries or even millennia. Upward flow of solutes through the chemocline is limited by diffusion mechanism which is extremely slow process. Microbial community of chemocline depends on this weak upward diffusion flow of nutrients. This is what we see in the studied lagoon: there are orders of magnitude more nutrients in the anaerobic monimolimnion than in the epilimnion, but they are inaccessible to aerobic organisms of the overlying stratum.

Reviewer's note:     I don’t see much evidence that you are interested in the drivers for the plankton biomass and  dynamics, which are something some readers would be interested in.

Reply: Indeed, the factors are insufficient. In the next work, we will include nutrients, etc.

And again: thank you very much!

Elena Krasnova

 

Author Response File: Author Response.docx

Reviewer 2 Report

REVIEW OF THE ARTICLE BY KRASNOVA ET AL. ENTITLED 'ANNUAL DYNAMICS OF LAYERED PHYTOPLANKTON STRUCTURE IN A MEROMICTIC LAGOON PARTIALLY ISOLATED FROM THE WHITE SEA' (diversity-2579458)

   The Authors studied phytoplankton diversity in a pond partially separated from the White Sea (Lagoon on the Cape Zeleny). This pond is characterised by an interesting feature, i.e. stratified structure of its water layers. Such unique ponds are widely disributed in the coastal zone of the White Sea. Krasnova et al. studied water physico-chemical parameters (pH, temperature, red-ox potential, and salinity) as function of depth. They found that the water column of the pond is divided into different zones strongly differed by their physico-chemical characteristics. In this zones they studied phytoplankton divesity in terms of morphospecies abundances. Notably, different zones of the statified lagoon were characterized by different morphospecies compositions. Annual dynamics of the parameters was also described. Although, the work was submitted by Russian authors, I definitely recommend appreciate this paper for publishing in Diversity. The article is in scope of the journal. The data is interesting for both researchiers tudying biodiversity in the White Sea region as well as for general specialsits in the field of plankton research and microbial ecology. Introduction is well-written, it sufficiently describes recent beckground in the field. Methods and object descriptions are sufficient. Results are clearly presented. Figures and tables are informative. I have not detected any conceptual and methodological drawbacks. There are only several editing and language points (please, see below). All suggestions are of a recommendatory nature.

-There is one formal issue: according to journal's rules, "the abstract should be a total of about 200 words maximum", number of keywords should be 3-10. Currently, the size of abstract is over 350 words.. It should be shortened. Number of keywords also should be reduced.

-According to journal rules, the word "Figure" should be written in full (not "Fig.".

-For uniformity, please, use Eh for the red-ox potential as on the figure instead of ORP.

-l. 123-124. Please, mention, that you mean temperature on the Celsius scale.

-l. 158. In English, "formaldehyde" is preferable.

-l. 157-194. According to the journal rules, each device should be indicated in the frmat DEVICE ([manufacturer name], [City], [State for US], [Country]). For example, "LuxLiner LMI-20 light meter (China)" should be "LuxLiner LMI-20 light meter (MetroniX, Beijing, China)"

-l. 167-168. According to the journal rules, an accession date should be indicated for the world-weather.ru.

-l. 167. "length of the daylight" - what do you mean? Daytime? wavelength of the light? Please, indicate clearly.

-l. 176. Pleae, indicate the date of accession to AlgaeBase (preferably, later). The same should be in the reference list.

-l .179-182. Please, indicate the procedure of sample preparation or add a reference.

-l. 185-193. Reference to the on-line resource should be moved to the reference list with an accession date.

-l. 199. "Bray-Curtis similarity" should be "Bray-Curtis similarity index".

-l. 216. Manufacturer should be indicated for Excel.

-l. 288, Table 1 (first). The last line in the table is redundant. It seems to be only 10 phyla were detected, because cryptophytes were not detected. Isn't it?  But later (subsection 3.5) you stated, cryptomonads were detected.

-l. 315, 321, 337, 369, 374, 383. " was 38% determined by 19 species", "was 37% determined by 16 species" - cannot understand. Please, revise.

-l. 508. There is one negative and one positive.

-You can compare phytoplankton composition in the upper layer of the lagoon with previous data on the White Sea an freshwater ponds of this region (10.1007/s10750-018-3844-0, 10.1007/s00248-017-1076-x).

-l. 654. Reference is required.

-l. 707. What is T?

-You have two "Table 1". Plese, check numbering.

-Table 1 (first). Wrong spelling Myozoa. What do you mean on the "number of taxa"? Taxa of which rank? Please, explain in the legend.

-Table 1 (second). Micracanthodinium claytonia - do you mean Micracanthodinium claytonii?

-Table 1-3. I am not sure about table format according the journal rules. Is it acceptable to include color tables?

-Figure 3. It is better to replace PSU with ‰ as in the text or vice versa.

-Figure 4. For uniformity, units (X-axis) should be near the axes names (as on other figures).

-Figure 3-5. Please, explain in the legend, what Roman numbers mean.

-Figure 6. Wrong spelling Myozoa. Abbreviation NCF should be explained in the legend.

-Figure 8. The figure contains Russian words!! Please, revise. What do Roman numbers mean?

-Table 1-3. Describe an abbreviation NCF in the legend.

-The authors are focused mostly on the taxa of diatoms, dinophytes and cryptophytes, most likely due to their simple morphological determination. No spetial attention was payed to green algae. It seems to be, their morphological determination is challeging. It could be mentioned as a limitation of the study.

-In general, the text is readable. Minor grammar and style errors are detected. I belive, it will be improved at the stage of language editing (l. 421. were the same, l. 433. Revise, l. 544. "solar insolation", l. 605-607. the sentence is weak due to double negation, etc.).

-Major point: the Results should be written in the Past (subsections 3.1, 3.2, 3.6). 

Author Response

Dear colleague! It was nice to read your review. Many thanks for the corrections and informative suggestions. We tried to take into account all the comments.

Reviewer's note:     -There is one formal issue: according to journal's rules, "the abstract should be a total of about 200 words maximum", number of keywords should be 3-10. Currently, the size of abstract is over 350 words. It should be shortened. Number of keywords also should be reduced.

Reply: Thank you. You are right. We have reduced the abstract (200 words) and shortened the list of the keywords (9).

In a saline Lagoon on the Cape Zeleny (White Sea), the annual dynamics of the vertical hydrological structure, and the seasonal dynamics of phytoplankton were traced, including species composition, and vertical distribution, abundance, nutrition type, and biomass. 293 species and supraspecific taxa of algae and cyanobacteria were found. Most of the identified species are marine, and 38 species are freshwater. Similarity between the communities of different horizons was 32-46% in summer and 7% in winter. Chemocline layer contained a maximum of phytoplankton biomass, 1-2 orders of magnitude higher than that in the overlying horizons. Phytoplankton structure in the surface water in the Lagoon and in the sea  layers differs significantly in composition, quantitative parameters, and seasonal dynamics. In terms of biomass, the Lagoon lags behind the sea until mid-summer, but, starting from August, it outnumbers it, and the phytoplankton development in the Lagoon lasts longer, until late autumn. According to DistLM analysis phytoplankton structure and dynamics in the Lagoon and the sea by 24.5% was related to the daylight, water salinity, oxygen content and pH, but did not depend on water T, underwater illuminance, and depth. The daylight length seems to be the crucial factor of the seasonal PhP dynamics.

 

Reviewer's note:     -According to journal rules, the word "Figure" should be written in full (not "Fig.".

Reply: Thank you. Corrected.

Reviewer's note:     -For uniformity, please, use Eh for the red-ox potential as on the figure instead of ORP.

Reply: Thank you. Corrected.

Reviewer's note:     -l. 123-124. Please, mention, that you mean temperature on the Celsius scale.

Reply: Thank you. Corrected.

In the section “Study area”:

“ In November sea water temperature in Celsius degrees is still positive, but in the Lagoon the water surface cools down to negative temperature, and young ice reaches a thickness of 1-2 cm”.

In the section “Results” – “Hydrological Conditions”:
“The seasonal course of temperature in the adjacent marine area is similar to that in the surface layer of the Lagoon, but summer temperature is 1-5 Celsium degrees lower in the sea”.

“Winter cooling to negative temperature (°C) covers the upper 4 m of the water column; starting from 4.5 m and below, the temperature is positive throughout the year”.

Reviewer's note:     -l. 158. In English, "formaldehyde" is preferable.

Reply: Thank you. Corrected.

Reviewer's note:     -l. 157-194. According to the journal rules, each device should be indicated in the frmat DEVICE ([manufacturer name], [City], [State for US], [Country]). For example, "LuxLiner LMI-20 light meter (China)" should be "LuxLiner LMI-20 light meter (MetroniX, Beijing, China)"

Reply: Thank you. For those measuring devices about which this can be found out, the city and country have been added.

Reviewer's note:     -l. 167-168. According to the journal rules, an accession date should be indicated for the world-weather.ru.

Reply: Thank you. Added.

Reviewer's note:     -l. 167. "length of the daylight" - what do you mean? Daytime? wavelength of the light? Please, indicate clearly.

Reply: We mean portion of the day when the Sun shines on a defined location. We've come across this term before and the reviewer suggested calling it daylight. There are synonyms: daylength, day length, duration of the day, daytime, daylight hours. Now we have decided to use the term daylength in this article.

Reviewer's note:     -l. 176. Pleae, indicate the date of accession to AlgaeBase (preferably, later). The same should be in the reference list.

Reply: We have checked the taxonomy. The species have not changed, but the classes and orders have changed. In this regard, we have changed the text, table and figure. Link with the date of revision of the article:

M.D. Guiry in Guiry, M.D. & Guiry, G.M. December 06, 2016. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 31.08.2023.

Reviewer's note:     -l .179-182. Please, indicate the procedure of sample preparation or add a reference.

Reply: The procedure for preparing samples to examination in scanning electron microscopy was carried out according to the Simonsen method (Sournia, 1978).

Reviewer's note:     -l. 185-193. Reference to the on-line resource should be moved to the reference list with an accession date.

Reply: Thank you. Done.

Reviewer's note:     -l. 199. "Bray-Curtis similarity" should be "Bray-Curtis similarity index".

Reply: Thank you. Done.

Reviewer's note:     -l. 216. Manufacturer should be indicated for Excel.

Reply: Thank you. Done.

Reviewer's note:     -l. 288, Table 1 (first). The last line in the table is redundant. It seems to be only 10 phyla were detected, because cryptophytes were not detected. Isn't it?  But later (subsection 3.5) you stated, cryptomonads were detected.

Reply: Cryptophytes were found but not identified to a lower rank.

Reviewer's note:     -l. 315, 321, 337, 369, 374, 383. " was 38% determined by 19 species", "was 37% determined by 16 species" - cannot understand. Please, revise.

Reply: To make it clearer, we changed the first mention of similarity percentages:

According to SIMPER analysis similarity of communities in different horizons was 38% based on 19 species. Major contributors were dinoflagellate Heterocapsa rotundata and prasinophyte flagellate Pyramimonas cf. diskoicola. Reviewer's note:     

Reviewer's note:    -l. 508. There is one negative and one positive.

Reply:  Thank you. We added the minus sign:

… (-0.31 and -0.39, respectively).

Reviewer's note:      -You can compare phytoplankton composition in the upper layer of the lagoon with previous data on the White Sea an freshwater ponds of this region (10.1007/s10750-018-3844-0, 10.1007/s00248-017-1076-x).

Reply: The first article describes cyanobacteria in rock baths only. Eukaryotes are represented by genera names only. The ecology of baths is significantly different from separating lakes.

The second article is devoted to picoeukaryotes, which we did not take into account in the present study. It is impossible  to determine this size fraction using light microscope. In addition, in the proposed article, not phytoplankton, but ice  picoalgae were studied.

Nevertheless, according to the phytoplankton of the Kandalaksha Bay of the White Sea (Cupa Bay), a study of the seasonal dynamics of phytoplankton was carried out. In the near future, an article will be prepared with comparison of species composition in the lagoon, other separating water bodies and some areas of the White Sea.

Reviewer's note:      -l. 654. Reference is required.

Reply: Thank you. Done.

Reviewer's note:      -l. 707. What is T?

Reply:  We meant temperature. Done.

Reviewer's note:      -You have two "Table 1". Plese, check numbering.

Reply:  Done.

Reviewer's note:      -Table 1 (first). Wrong spelling Myozoa. What do you mean on the "number of taxa"? Taxa of which rank? Please, explain in the legend.

Reply:  We have corrected the name Myozoa  and changed “Number of taxa” to “Number of species”.

 Reviewer's note:      -Table 1 (second). Micracanthodinium claytonia - do you mean Micracanthodinium claytonii?

Reply: You are right. Corrected.

Reviewer's note:      -Table 1-3. I am not sure about table format according the journal rules. Is it acceptable to include color tables?

Reply: We used color shading in the tables to make them easier to read. If according to the rules of the magazine this is not possible, then we can either use a gray scale, or give a table without filling at all. At the discretion of the editorial board.

Reviewer's note:      -Figure 3. It is better to replace PSU with ‰ as in the text or vice versa.

Reply:  Done.

Reviewer's note:      -Figure 4. For uniformity, units (X-axis) should be near the axes names (as on other figures).

Reply:  Done.

Reviewer's note:      -Figure 3-5. Please, explain in the legend, what Roman numbers mean.

Reply:  Roman numerals indicate months. Added to the legend.

Reviewer's note:      -Figure 6. Wrong spelling Myozoa. Abbreviation NCF should be explained in the legend.

Reply:  Done.

Reviewer's note:      -Figure 8. The figure contains Russian words!! Please, revise. What do Roman numbers mean?

Reply:  I and II indicate groups of the samples combined by non-metric multidimensional scaling (nMDS) by phytoplankton biomass. Added to the legend^

I and II indicate groups of the samples combined by non-metric multidimensional scaling (nMDS) based on phytoplankton biomass.

Reviewer's note:     -Table 1-3. Describe an abbreviation NCF in the legend.

Reply: NCF – not identified cocci and flagellates. Added to the legend.

Reviewer's note:    

-The authors are focused mostly on the taxa of diatoms, dinophytes and cryptophytes, most likely due to their simple morphological determination. No spetial attention was payed to green algae. It seems to be, their morphological determination is challeging. It could be mentioned as a limitation of the study.

Reply: You're right. We looked through the samples totally and identified not all species. Not identified cocci and flagellates (NCF) could be both Cyanobacteria and Chrysophyta, etc. Yes, we did not determine small green (and not only) algae, and included them in the NCF group. In the “sample proceeding” section was honestly specified: “Unidentified algae were divided into size groups according to the maximum linear size. Coccoid and flagellated cells that have not been identified were combined into a group of NCF (not identified cocci and flagellates) with gradation by size”.

Reviewer's note:    Comments on the Quality of English Language

-In general, the text is readable. Minor grammar and style errors are detected. I belive, it will be improved at the stage of language editing (l. 421. were the same, l. 433. Revise, l. 544. "solar insolation", l. 605-607. the sentence is weak due to double negation, etc.).

Reply: Thank you. Corrected.

Reviewer's note:     -Major point: the Results should be written in the Past (subsections 3.1, 3.2, 3.6).

Reply: Thank you. Corrected.

And again: thank you very much!

Elena Krasnova

 

Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript "Annual Dynamics of Layered Phytoplankton Structure in a Meromictic Lagoon Partially Isolated from the White Sea" is devoted to the study of the phytoplankton seasonal dynamics in such an unusual habitat as the meromectic lagoon. In such reservoirs, a vertical division into layers with different salinity is observed. In the studied lagoon, these layers are stable despite water exchange with the sea. Therefore, it is here that it is interesting to study the vertical distribution of phytoplankton. The authors are successful in this task. The manuscript describes clearly and in great detail the problem of meromectic reservoirs and the lagoon studied in this work. The results are presented very clearly. The discussion is very detailed and exhaustive. A very valuable result is the distribution of phytoplankton by mode of nutrition, depending on the depth.

However, the total species composition of phytoplankton, with the exception of the dominant and typical species, remains a mystery. It would be nice to attach a list of all species found in the phytoplankton of the lagoon. For typical species and dominants, it would be nice to add photos.

In "Results", it would be good to list all typical species for the lagoon, as also to present species that was noted only in one layer of the lagoon and not found in others.

The paper indicates that the similarity with the adjacent marine area is low (10 - 47%), so in the lagoon there are unique species that live only in there? Maybe the authors can assume what caused such a big difference in the species composition between the lagoon and the White Sea?

I would like to recommend the authors to write the first mention of the Latin name of the species with the author and year.

I draw the attention of the authors that in the manuscript two tables are numbered 1 (tables on p.8 and 14). Accordingly, it is necessary to check the numbering of tables in the text, especially on L. 302.

In Table 1 the values of Bc and the contribution of dominants to Bc are shown. If I understood correctly, then Bc is the total biomass of all phytoplankton.Maybe it would be better to represent the contribution of dominants in % ?

Table 2 missing many "Space" characters.

L. 349: it will be better: unidentified species with green oval cells.

Figure 8: in the top legend there are captions not translated into English.

The Сonclusions are very large and require reduction to the most significant results.

 

 

 

In general, English is good, but sometimes there are sentences that are too long and difficult to understand.

Author Response

Dear colleague! It was nice to read your review. Many thanks for the corrections and informative suggestions. We tried to take into account all the comments.

Reviewer's note:     Manuscript "Annual Dynamics of Layered Phytoplankton Structure in a Meromictic Lagoon Partially Isolated from the White Sea" is devoted to the study of the phytoplankton seasonal dynamics in such an unusual habitat as the meromictic lagoon. In such reservoirs, a vertical division into layers with different salinity is observed. In the studied lagoon, these layers are stable despite water exchange with the sea. Therefore, it is here that it is interesting to study the vertical distribution of phytoplankton. The authors are successful in this task. The manuscript describes clearly and in great detail the problem of meromictic reservoirs and the lagoon studied in this work. The results are presented very clearly. The discussion is very detailed and exhaustive. A very valuable result is the distribution of phytoplankton by mode of nutrition, depending on the depth.

Reviewer's note:     However, the total species composition of phytoplankton, with the exception of the dominant and typical species, remains a mystery. It would be nice to attach a list of all species found in the phytoplankton of the lagoon. For typical species and dominants, it would be nice to add photos.

Reply: Thank you. We consider preparing one more paper devoted exclusively to the species composition of the studied lagoon, including not only those species that we will have met in 2020, but also encountered in other years. The summary list is much larger and more informative. In this article, we focused more on the dynamics and vertical differences of communities in this unusual water object.

Reviewer's note:     In "Results", it would be good to list all typical species for the lagoon, as also to present species that was noted only in one layer of the lagoon and not found in others.

The paper indicates that the similarity with the adjacent marine area is low (10 - 47%), so in the lagoon there are unique species that live only in there? Maybe the authors can assume what caused such a big difference in the species composition between the lagoon and the White Sea?

Reply:  Thank you for the very helpful advice. We add Supplementary Materials with the list of the phytoplankton taxa and their occurrence at different depths.

Our similarity analysis takes into account not only the presence or absence of individual species, but also their biomass. This method compares the structure of phytoplankton. Even with the same species composition, the community structure can vary greatly if the quantitative contribution of individual species varies greatly; in this case the percentage similarity can be small. Regarding unique species, yes, and this is noted in the "discussion" section. Indeed, in the lagoon there are species that have not yet been found in the neighboring marine area, and not even registered in the entire White Sea. There are prerequisites for discovery of a few new species. But in this article we do not write about it yet. We will leave it for a future article, without such a detailed analysis of the ecological features of this marvelous stratified lagoon.

Reviewer's note:     I would like to recommend the authors to write the first mention of the Latin name of the species with the author and year.

Reply: We understand this recommendation. In taxonomic studies, this is indeed necessary. We have checked how the Latin species names are formatted in other articles of “Diversity” journal and noticed that author and the year of the first species description are rarely  indicated in ecological articles. Therefore, we will not change the design in this article, but we will take it into account when preparing the next article on the species composition of the lagoon.

For example, ecological articles in “Diversity”, in which authors and years of description were not indicated:

https://www.mdpi.com/1424-2818/15/9/975

https://www.mdpi.com/1424-2818/15/9/976

https://www.mdpi.com/1424-2818/15/8/937

https://www.mdpi.com/1424-2818/15/8/934

https://www.mdpi.com/1424-2818/15/8/901

https://www.mdpi.com/1424-2818/15/8/888, and many others.

However, we decided to follow your advice and included the authors and years in the full list of species encountered in the Supplementary materials, which were not in the previous version of the manuscript.

Reviewer's note:     I draw the attention of the authors that in the manuscript two tables are numbered 1 (tables on p.8 and 14). Accordingly, it is necessary to check the numbering of tables in the text, especially on L. 302.

Reply: Thank you. Done.

Reviewer's note:     In Table 1 the values of Bc and the contribution of dominants to Bc are shown. If I understood correctly, then Bc is the total biomass of all phytoplankton. Maybe it would be better to represent the contribution of dominants in % ?

Reply: If the contributions are transferred from shares to percentage, this can confuse the reader. We use percentages in the similarity value.

Reviewer's note:     Table 2 missing many "Space" characters.

Reply: Thank you. Corrected.

Reviewer's note:     L. 349: it will be better: unidentified species with green oval cells.

Reply: Thank you. Corrected.

Reviewer's note:     Figure 8: in the top legend there are captions not translated into English.

Reply: Thank you. Corrected.

Reviewer's note:     The Сonclusions are very large and require reduction to the most significant results.

Reply: Thank you. Shortened.

 Comments on the Quality of English Language

Reviewer's note:     In general, English is good, but sometimes there are sentences that are too long and difficult to understand.

Reply: Thank you. This time the text was checked more carefully, with the participation of a colleague who speaks English well.

And again: thank you very much!

Elena Krasnova

Author Response File: Author Response.docx