Role of Hydrology in Cyanobacterial Blooms in the Floodplain Lakes

Round 1

Reviewer 1 Report

The authors summarized the impacts of hydrology in affecting Cyanobacterial blooms in the floodplain lakes. The information included in this paper is comprehensive but the some of them need to be reorganized. Introduction part also needs improvement by adding some general impacts of cyanobacterial bloom so reader will not feel different sections are disconnected. Suggest reconsider after major revision.

1.      Line 16: add a "," before and

2.      Line 86: suggesting adding a short paragraph to describe cyanobacterial bloom in general using the following papers. it does not have to be in floodplain lakes. That explains why you focused on cyanobacterial blooms summary.

for example,  CyanoHABs have substantial impacts on the functioning and sustainability of freshwater ecosystems by restricting light penetration, depleting dissolved oxygen, and producing various toxins (Huisman et al., 2018). Cyanobacterial blooms alter the relative importance of neutral and selective processes in assembling freshwater bacterioplankton community (Wang et al., 2020).

Wang, K., Razzano, M., & Mou, X. (2020). Cyanobacterial blooms alter the relative importance of neutral and selective processes in assembling freshwater bacterioplankton community. Science of the Total Environment, 706, 135724.

Huisman, J., Codd, G. A., Paerl, H. W., Ibelings, B. W., Verspagen, J. M., & Visser, P. M. (2018). Cyanobacterial blooms. Nature Reviews Microbiology, 16(8), 471-483.

3.      Line 92: suggesting the following sentences of this paragraph summarize connectivity based on these four dimensions if possible.

4.      Line 114: change to "Cyanobacterial blooms in floodplain lakes "

5.      Line 133: this first part of this paragraph is discussing WLF. separate this paragraph into two paragraphs. and add a topic sentence for the second half of this paragraph.

6.      Line 176: as your previous sentence mentioned, these preferences differ among species. suggest revising this sentence to "for example, nitrogen deficiency was found favoring the occurrence of common N-fixing Nostocales [81], while N-rich was found supporting N-fixing Anabaena (Wang et al., 2021)."

Wang, K., Mou, X., Cao, H., Struewing, I., Allen, J., & Lu, J. (2021). Co-occurring microorganisms regulate the succession of cyanobacterial harmful algal blooms. Environmental Pollution, 288, 117682.

7.      Line 193: suggest adding a sentence to show how nutrients in general affect cyanobacterial blooms, and then focus on different indiviual nutrients.

8.      Line 206: why is this sentence in bold?

I assume you want to discuss environmental factors on cyanobacterial blooms. suggest adding a few sentences to summarize all the environmental factors that may affect cyanobacterial bloom and also focus on temperature.

9.      Line 27: section number is not correct. And also the line number is not continued from the previous page.

10.   Line 51: suggest adding a few sentence to show what may be the potential ecological role of producing cyanotoxins.

11.   Line 84: section number is not correct. And also the line number is not continued from the previous page.

12.   Line 92: delete the extra space here

13.   Line 105-106: suggest summarizing this paragraph based on hydrodynamic management, nutrients management, and others

Author Response

Responses to the Reviewer’s 1 comments

Thank you for the time and effort put into improving our manuscript.

1. Line 16: add a "," before and

Response: Line 16 (now 17) : a "," before and has been added

2. Line 86: suggesting adding a short paragraph to describe cyanobacterial bloom in general using the following papers. it does not have to be in floodplain lakes. That explains why you focused on cyanobacterial blooms summary. 

Response: a short paragraph describing cyanobacterial bloom in general has been added (lines 84-93). A below reference has been cited:

Wang, K., Razzano, M., & Mou, X. (2020). Cyanobacterial blooms alter the relative importance of neutral and selective processes in assembling freshwater bacterioplankton community. Science of the Total Environment, 706, 135724.

Huisman, J., Codd, G. A., Paerl, H. W., Ibelings, B. W., Verspagen, J. M., & Visser, P. M. (2018). Cyanobacterial blooms. Nature Reviews Microbiology, 16(8), 471-483.

3. Line 92: suggesting the following sentences of this paragraph summarize connectivity based on these four dimensions if possible.

Response: Lines 98-102: the paragraph summarizing connectivity, based on the four dimensions has been provided. A below-mentioned references were cited:

Freeman, M.C., C.M. Pringle, and C.R. Jackson. 2007. Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales. Journal of the American Water Resources Association 43(1):5-14

Larned, S.T., T. Datry, D.B. Arscott, and K. Tockner. 2010. Emerging concepts in temporary river ecology. Freshwater Biology 55(4):717-738. 

4. Line 114: change to "Cyanobacterial blooms in floodplain lakes "

 Response: Line 114 (139 in the revised manuscript): has been changed to "Cyanobacterial blooms in floodplain lakes "

5. Line 133: this first part of this paragraph is discussing WLF. separate this paragraph into two paragraphs. and add a topic sentence for the second half of this paragraph.

Response: Line 133 (164 in the revised manuscript): the part of this paragraph discussing WLF has been separated this paragraph into two paragraphs.

The paragraph was divided and the topic sentence was added (line 186).

6. Line 176: as your previous sentence mentioned, these preferences differ among species. suggest revising this sentence to "for example, nitrogen deficiency was found favoring the occurrence of common N-fixing Nostocales [81], while N-rich was found supporting N-fixing Anabaena (Wang et al., 2021)."

Response: The sentence was rewritten and the information and citation were added (lines 217-219).

Wang, K., Mou, X., Cao, H., Struewing, I., Allen, J., & Lu, J. (2021). Co-occurring microorganisms regulate the succession of cyanobacterial harmful algal blooms. Environmental Pollution, 288, 117682.

7. Line 193: suggest adding a sentence to show how nutrients in general affect cyanobacterial blooms, and then focus on different individual nutrients.

Response: a sentence to show how nutrients in general affect cyanobacterial blooms was added at the beginning of the paragraph (lines 242-243 in the revised manuscript).

8. Line 206: why is this sentence in bold?

Response: The sentence was not in bold in the original version. The editing changed automatically during the conversion into the Water journal form. It has been corrected

9. Line 27: section number is not correct. And also the line number is not continued from the previous page.

Response: Line 27: the mixed-up with line numbering occurred during the submitting process, probably due to the previous table content. Re-submitted manuscript will be submitted using the Water form sheet, to avoid this problem.

10. Line 51: suggest adding a few sentence to show what may be the potential ecological role of producing cyanotoxins.

Response: The information was added and below references were cited (lines 356-363).

Welker M, Döhren H (2006) Cyanobacterial peptides - nature's own combinatorial biosynthesis. FEMS Microbiol Rev 30:530–563

Holland, A., & Kinnear, S. (2013). Interpreting the possible ecological role (s) of cyanotoxins: compounds for competitive advantage and/or physiological aide?. Marine drugs, 11(7), 2239-2258.

Hu, C., Rzymski, P. (2019). Programmed cell death-like and accompanying release of microcystin in freshwater bloom-forming cyanobacterium Microcystis: from identification to ecological relevance. Toxins, 11(12), 706.

11. Line 84: section number is not correct. And also the line number is not continued from the previous page.

Response: Line 84: the line numbering have been correcting by the Water template.

12. Line 92: delete the extra space here

Response: the extra space was deleted

13. Line 105-106: suggest summarizing this paragraph based on hydrodynamic management, nutrients management, and others

Response: A paragraph summarizing management practices has been added. Additional papers have been cited:

Mallakpour, I., & Villarini, G. (2015). The changing nature of flooding across the central United States. Nature Climate Change, 5(3), 250–254. https://doi.org/10.1038/nclimate2516

Brierley GJ, Fryirs KA, Jain V (2006) Landscape connectivity: the geographic basis of geomorphic applications. Area 38(2):165–174. https://doi.org/10.1111/j.1475-4762.2006.00671.x

Bayley, P. B. (1995). Understanding large river-floodplain ecosystems. BioScience, 45(3), 153–158. https://doi.org/10.2307/1312554

Reviewer 2 Report

This is an interesting study. However ,few issues should be addressed before publication:

1.       Hydrology includes several components, such as what level, volume, surface area, residence time, et al, but only few are involved in this article.

2.        3. Water management practices in floodplain lakes should be 5. Water

Author Response

Responses to the Reviewer’s 2 comments

Thank you for your remarks. We took all of them into consideration.

1. Hydrology includes several components, such as water level, volume, surface area, residence time, et al, but only a few are involved in this article.

Response:

This is a valid remark. Floodplain lakes hydrology (like any other lake) includes many components. However, unlike other lakes, floodplain lakes are extremely difficult to investigate, e.g. in terms of residence time.

Thus, hydrological parameters and processes have been interweaving into the manuscript, without a detailed description. Water level fluctuation, extremely high and frequent compared to lakes of other origin, is described most commonly (and its biological implications in the ecosystems). The dynamic WL variation causes drastic changes in the bathymetry of the lake (area and volume; described in the Introduction section, lines 60-70). A description of the hydrologic functioning of these types of lakes has been added at the beginning of section 5. Horizontal water balance elements are of major importance in floodplain lakes (lines 444-448). they cause both matter and energy fluxes (described in lines 235, 321, 322, 434), as well as determine bathymetry changes (described in lines:….) and flushing time (which measure the same process as residence time) (described in lines: 22-23, 127, 178)                                                                                                                                                                                                                                                                                                                  

3. Water management practices in floodplain lakes should be 5. Water

Response:

 The mixed-up with both lines and reference numbering occurred due to conversion during paper submission. Numbers have been corrected and the Water template was used to avoid such problems in the future.

Reviewer 3 Report

Journal: Water (ISSN 2073-4441)

Manuscript ID: water-2266195

Type: Review

Title: Role of hydrology in Cyanobacterial blooms in the floodplain lakes

Section: Water Quality and Contamination

This manuscript aims to summarize role of hydrology in occurrence of cyanobacterial blooms and cyanotoxin production in the floodplain lakes. I have the following comments and suggestions for the authors to improve the quality of the manuscript.

1. Table 1. Cyanobacterial blooms in chosen floodplain lakes

Page 5, lines 180-183

“Oscillatoriales such as P. agardhii and Limnothrix spp., which co-dominated seasonally (often in winter periods) in most of the analysed floodplain lakes (Table 1), [50, 60, 75, 76, 78], prefer turbulent conditions [83], however, according to Reynolds [81] they are sensitive to flushing.”

Why did you choose these lakes for analysis? What are the selection conditions? Please explain and add some text in the revised manuscript.

2. Section “3. Cyanobacterial predomination and blooms in floodplain lakes”

Which environmental factors can affect cyanobacterial predomination and blooms in floodplain lakes? Any differences of the environmental factors affecting cyanobacterial predomination and blooms in floodplain lakes and non- floodplain lakes? Please add some text.

3. Section “3. Cyanotoxins in floodplain lakes”

Which environmental factors can affect concentrations of cyanotoxins in floodplain lakes? Any differences of the environmental factors affecting concentrations of cyanotoxins in floodplain lakes and non- floodplain lakes? Please add some text.

4. The manuscript lack analysis of role of hydrology in occurrence of cyanobacterial blooms and cyanotoxin production in the floodplain lakes. Please add some sections on this topic, which would the highlight of the manuscript.

5. Pages 4-5, lines 133-192

This paragraph is too long. Please divide it to two or more paragraphs.

6. Page 10, lines 47-48

“Over 240 MC isoforms have been described [99], out of which MC-LR, MC-RR, and MC-YR are the most frequently producing and extensively studied, very toxic variants.”

Over 279 MC isoforms have been described. Please read and cite the following paper. In fact, you have already cited this paper (Ref. 100 or 95).

Challenges of using blooms of Microcystis spp. in animal feeds: A comprehensive review of nutritional, toxicological and microbial health evaluation. Stoten 2021, 764, 142319. https://doi.org/10.1016/j.scitotenv.2020.142319

7. Title

Please change “Cyanobacterial” to “cyanobacterial”.

8. Reference list

There are two numbers for every reference. And starting from 45, the two numbers are different. Please check it.

Author Response

Responses to the Reviewer’s 3 comments

Response: Thank you for all your valuable comments and suggestions. All were taken into consideration.

1. Table 1. Cyanobacterial blooms in chosen floodplain lakes

Page 5, lines 180-183

“Oscillatoriales such as P. agardhii and Limnothrix spp., which co-dominated seasonally (often in winter periods) in most of the analysed floodplain lakes (Table 1), [50, 60, 75, 76, 78], prefer turbulent conditions [83], however, according to Reynolds [81] they are sensitive to flushing.”

Why did you choose these lakes for analysis? What are the selection conditions? Please explain and add some text in the revised manuscript.

Response: We chose lakes for analysis on the basis of the available literature data, which is quite scarce because studies on cyanobacterial blooms and cyanotoxin production in floodplain lakes are rare as was pointed out in lines 24, 359, 510. The selection conditions were the classification of lakes as floodplain lakes and the availability of data on the abundance and/or biomass of cyanobacteria, chlorophyll-a concentration (as an equivalent of phytoplankton biomass) and the occurrence and seasonal dynamics of particular cyanobacterial species (Table 1). We also analyzed available literature data on toxin production (if possible seasonal cyanotoxin dynamics) in selected lakes and compared them with lakes hydrology where it was possible (lines 359-371). All lakes discussed in the text are characterized in Table 1. We removed “chosen” from the title of Table 1 as it can be misleading, suggesting that not all discussed lakes are presented in the Table.

The text explaining the methods of selection was added in the revised manuscript (lines 102-110).

2. Section “3. Cyanobacterial predomination and blooms in floodplain lakes”

Which environmental factors can affect cyanobacterial predomination and blooms in floodplain lakes? Any differences of the environmental factors affecting cyanobacterial predomination and blooms in floodplain lakes and non- floodplain lakes? Please add some text.

Response: The information was added (lines 306-329) and additional references were cited.

Summing up, in different water bodies, cyanobacterial predomination and blooms are favored mostly by physical-chemical conditions including high nutrient concentrations and higher water temperatures [Husmain et al. ]. However, in floodplain lakes, except for the above-mentioned parameters, the main drivers that affect cyanobacterial blooms are hydrological factors (Table 1). The factors that favor blooms, mainly in river-connected lakes, are extremely low water levels [75, 76] and stability of the water column [50,60], being a result of low WLFs [6,57] and the dynamics of flooding and its intensity [50,60]. On the other hand, nutrient enrichment of lakes supplied by river water at simultaneously higher water levels can also drive cyanobacterial blooms in some floodplain lakes [14, 55, 77], particularly in those macrophyte-dominated [78]. Nevertheless, in general, both in floodplain lakes and in other types of lakes, as well as in different flow-through artificial and natural water bodies [67, Mantzouki et al. 2019, Pawlik-Skowrońska and Toporowska 2011, Grabowska 2005] eutrophication, high temperatures and poor mixing are the main factors. For example, in eutrophicated large water bodies with poor vertical mixing [Jöhnk et al. 2008, Grabowska 2005, Mankiewicz-Boczek et al. 2006] and high water temperatures (>20°C), the Microcystis abundance can increase rapidly within a few days. Hydrology, including WLFs, flushing, and water retention time, after eutrophication and temperature conditions, is a very important factor influencing cyanobacterial bloom development and depletion not only in floodplain lakes (Table 1), but also in flow-through lakes and reservoirs [Pawlik-Skowrońska and Toporowska 2016, Toporowska et al. 2018]. In water bodies without outflow, where physical-chemical conditions and size (mixing) are the main drivers of cyanobacterial blooms, the hydrological role is relevant in the light of supplying nutrients from the catchment, however, not single variables but complex lake-catchment processes decide the functioning of water bodies and phytoplankton qualitative and quantitative structure and water blooms [Toporowska et al 2018].

Cited references:

Pawlik-Skowrońska, B., & Toporowska, M. (2011). Blooms of toxin-producing Cyanobacteria—A real threat in small dam reservoirs at the beginning of their operation. Oceanological and Hydrobiological Studies, 40, 30-37.

Jöhnk K., Huisman J., Sharples J., Sommeijer B., Visser P.M., Strooms J.M., 2008, Summer heatwaves promote blooms of harmful cyanobacteria. Glob. Change Biol., 14: 495-512

Grabowska M., 2005, Cyanoprocaryota blooms in the polyhumic Siemianówka dam Reservoir in 1992-2003, Oceanol. Hydrobiol. Stud., 24(1): 73-85

Mankiewicz-Boczek J., Urbaniak M., Romanowska-Duda Z., Izydorczyk K., 2006, Toxic cyanobacteria strains in lowland dam reservoir (Sulejów Res. central Poland): amplification of MCY genes for detection and identification, Pol. J. Ecol., 54: 171-180

Pawlik-Skowronska, B., & Toporowska, M. (2016). How to mitigate cyanobacterial blooms and cyanotoxin production in eutrophic water reservoirs?. Hydrobiologia, 778, 45-59. DOI 10.1007/s10750-016-2842-3

Toporowska, M., Ferencz, B., & Dawidek, J. (2018). Impact of lake‐catchment processes on phytoplankton community structure in temperate shallow lakes. Ecohydrology, 11(8), e2017. https://doi.org/10.1002/eco.2017

3. Section “3. Cyanotoxins in floodplain lakes”

Which environmental factors can affect concentrations of cyanotoxins in floodplain lakes? Any differences of the environmental factors affecting concentrations of cyanotoxins in floodplain lakes and non- floodplain lakes? Please add some text.

Response: The text was added (lines 364-377).

Studies on the production of cyanotoxins in floodplain lakes are extremely rare [88, 89, 90, 91]. Both in floodplain lakes and non-floodplain lakes, there is one main factor that decides the production of cyanotoxins: it is the presence and development of cyanobacterial strains able to produce MCs and other biologically active metabolites [Welker and Duren 2006, Mankiewicz and Boczek 2006]. On the other hand, it seems that in floodplain and non-floodplain lakes, the environmental factors influencing cyanotoxin production and concentration may be different. For example, studies [Pawlik-Skowrońska and Toporowska 2016] carried out in four lakes modified into water storage reservoirs (with periodically regulated water levels) and included in the river drainage canal system (Wieprz-Krzna), showed that in two larger lakes, into which nutrient-rich water was supplied once a year, lower cyanobacterial species diversity, higher biomass of cyanobacteria belonging to Microcystis, Aphanizomenon, and Dolichospermum, and higher MCs concentrations were found. In two other lakes, with several irregular water-level manipulations per year (alternating outputs and inputs), higher species diversity, lower cyanobacterial biomass and MC concentrations were observed. There were also differences in MC variants observed. Intracellular MC-LF, -LR and -RR produced by Microcystis spp. predominated in the more stable lakes, whereas in the lakes with frequent water manipulations different Oscillatoriales produced also MC-LA, -LY, -LW and -WR isoforms. This study showed that the frequency of water manipulations was the most significant factor for the composition of cyanobacterial communities and that a higher frequency of WLFs, which increases the flushing rate, was beneficial to nutrient-rich water reservoirs. The same phenomena might occur in floodplain lakes, and further studies in this field are strongly required. Data showing low concentrations of cyanotoxins in large Chinese floodplain lakes (Table 1) suggest that the environmental condition in these lakes are not favorable for high toxin production and concentrations. Moreover, frequent WTLs which are stress factors may cause cell breakdown and the release of extracellular toxins. This phenomenon may be extremely dangerous in water bodies which are reservoirs of drinking water and needs to be explored in floodplain lakes connected to the rivers.

4. The manuscript lack analysis of role of hydrology in occurrence of cyanobacterial blooms and cyanotoxin production in the floodplain lakes. Please add some sections on this topic, which would the highlight of the manuscript.

Response: The text was added (lines 287-290-308 and lines 306-329, respectively)

5. Pages 4-5, lines 133-192

This paragraph is too long. Please divide it to two or more paragraphs.

Response: The manuscript was divided into two paragraphs (line 190).

6. Page 10, lines 353-354

“Over 240 MC isoforms have been described [99], out of which MC-LR, MC-RR, and MC-YR are the most frequently producing and extensively studied, very toxic variants.”

Over 279 MC isoforms have been described. Please read and cite the following paper. In fact, you have already cited this paper (Ref. 100 or 95).

Challenges of using blooms of Microcystis spp. in animal feeds: A comprehensive review of nutritional, toxicological and microbial health evaluation. Stoten 2021, 764, 142319. https://doi.org/10.1016/j.scitotenv.2020.142319

Response: The information was actualized on the basis of the proper paper (line 356).

7. Title

Please change “Cyanobacterial” to “cyanobacterial”.

Response: the title was corrected.

8. Reference list

There are two numbers for every reference. And starting from 45, the two numbers are different. Please check it.

Response: The editing changed automatically numbers for references during the conversion into the Water journal form. The errors were corrected in the revised version.

Round 2

Reviewer 1 Report

One minor comment: 

line4: use superscript for the numbers

I'm good with the other replies. 

Author Response

Thank you for accepting our previous responses.

line4: use superscript for the numbers

Response:

superscript was used for the numbers

Reviewer 3 Report

Journal: Water (ISSN 2073-4441)

Manuscript ID: water-2266195

Type: Review

Title: Role of hydrology in Cyanobacterial blooms in the floodplain lakes

Section: Water Quality and Contamination

This manuscript aims to summarize role of hydrology in occurrence of cyanobacterial blooms and cyanotoxin production in the floodplain lakes. The review manuscript improved during the revisions. However, there are still some issues. I have the following comments and suggestions for the authors to improve the quality of the manuscript.

1. Table 1. Cyanobacterial blooms in floodplain lakes

Did you summarize all the studies on cyanobacterial blooms in floodplain lakes? If not, please change the title, may be “Cyanobacterial blooms in floodplain lakes (some examples)”

2. Section “3. Cyanobacterial blooms in floodplain lakes”

Please extract the text on role of hydrology in occurrence of cyanobacterial blooms in the floodplain lakes and insert a new section “4. Role of hydrology in occurrence of cyanobacterial blooms in the floodplain lakes”.

3. Section “4. Cyanotoxins in floodplain lakes”

Please extract the text on role of hydrology in cyanotoxin production in the floodplain lakes and insert a new section “6. Role of hydrology in cyanotoxin production in the floodplain lakes”.

Author Response

Thank you for your valuable remarks. The suggested changes have been implemented to improve manuscript quality.

1. Table 1. Cyanobacterial blooms in floodplain lakes

Did you summarize all the studies on cyanobacterial blooms in floodplain lakes? If not, please change the title, may be “Cyanobacterial blooms in floodplain lakes (some examples)”

Response:

The title of Table 1 has been changed to: Cyanobacterial blooms in floodplain lakes (selected examples)

2. Section “3. Cyanobacterial blooms in floodplain lakes”

Please extract the text on role of hydrology in occurrence of cyanobacterial blooms in the floodplain lakes and insert a new section “4. Role of hydrology in occurrence of cyanobacterial blooms in the floodplain lakes”.

Response:

The section 3 has been divided into two parts. A new section “4. Role of hydrology in occurrence of cyanobacterial blooms in the floodplain lakes” was provided.

3. Section “4. Cyanotoxins in floodplain lakes”

Please extract the text on role of hydrology in cyanotoxin production in the floodplain lakes and insert a new section “6. Role of hydrology in cyanotoxin production in the floodplain lakes”.

Response:

The aforementioned section was divided into two parts. A new section 6. Role of hydrology in cyanotoxin production in the floodplain lakes was inserted.