Removal and Temporary Cyst Formation of Gymnodinium catenatum (Dinophyceae) Using Calcium Bentonite Clay and Zeolite
, Erick J. Núñez-Vázquez 2,*, Leyberth J. Fernández-Herrera 2, Jannette GarcÃa-Zendejas 1, Ariel A. Cruz-Villacorta 3, José J. Bustillos-Guzmán 1, Daniel O. Ceseña-Ojeda 2 and David J. López-Cortés 4,†Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReview for the paper “Removal and temporary cyst formation of Gymnodinium catenatum (Dinophyceae) using calcium bentonite clay and zeolite” by Francisco E. Hernández-Sandoval and co-authors submitted to “Phycology”.
The authors of this research paper conducted an analysis of clay mineral applications for the flocculation and removal of a toxin producing dinoflagellate, focusing on comparative performance and cellular responses. Using microscopy and elemental microanalysis to characterize the materials, they evaluated how bentonite and zeolite behaved in different aqueous matrices and how these interactions affected algal biomass indicators and cell integrity. They found that bentonite exhibited substantially greater flocculation efficiency than zeolite and that the mode of water used to suspend the clays influenced removal performance and postflocculation cell condition. They also observed a range of external cellular effects associated with bentonite sediment matrices, including impaired motility, structural deformation, cell rupture, and formation of transient cystlike stages following exposure. The results of this study may have important implications for operational mitigation strategies and environmental risk assessment.
Recommendations.
Introduction.
L 39-40. The authors should contextualize this trend. They should provide specific regions or examples where the increase in the frequency and intensity of harmful algal blooms occurs.
L 42. The authors should specify measurable impacts on fisheries, aquaculture, and tourism. For instance, do HABs cause fish mortality, reduced yields, or public health warnings that deter tourism?
L 49-50. The authors should provide data or examples illustrating how much clay is typically used during mitigation and the severity of its impact on substrate and organisms.
L 54-55. The authors should provide examples or quantitative data on the specific economic and health problems caused by this species along Mexico's Pacific coast.
The authors should provide a brief description of previous research in this field and identify knowledge gaps.
Material and Methods.
L 77. The authors should specify the purpose of allowing the clay dilutions to stand before use. Does this improve dispersion, hydration, or other properties?
L 100. Did the authors check the data for normality and homogeneity of variance, as required for parametric tests (ANOVA)? What methods did they use?
Subsection 2.5 should be placed at the end of the "Materials and Methods" section.
L 114-115. The authors should clarify whether the observations of adhesion (using microscopy) were quantitative or qualitative.
L 130. The authors should provide information on the identity and concentration of the pigment standards.
Results.
L 139. The authors should italicize "Gymnodinium catenatum"
Figure 1. The authors should explain the meaning of the vertical bars.
Figure 2. The authors should explain the meaning of the violet lines.
L 164, 173, 182, 190, 200, 207, 214, 224. The authors should italicize "G. catenatum"
Figures 3 and 5. The OX axis should be labeled as "Number of cells, cell mL–1" instead of "G. catenatum (cell mL–1)".
Discussion.
L 231-232. The authors should specify how the medium contributes to the flocculation process. Does the ionic composition, salinity, or pH of the medium affect the interaction between the clay particles and algal cells?
L 265-267. The authors should provide additional details on how the surfactant foam methodology compares to clay-based approaches in terms of cost, scalability, environmental impact, and efficiency.
L 286-288. The authors should explain whether reduced swimming ability is purely mechanical (weight of adhered particles) or biochemical (disturbance of ionic balance).
The authors should discuss the practical applications of their results and provide recommendations.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThere were 9 citations of the corresponding author
Line 21 What is meant by ‘naked’ dinoflagellate?
Line 24 Clays will not fully dissolve in water. It would be more representative to say clays were added to water.
Line 41 ‘]’ in red font
Line 47: Clays can be effective at removing something from water, not really in mititating declining economic losses.
Line 56 spelling of authors.
Line 59: what were the two types of clays and laboratory conditions? What were the hypotheses for the study? What threshold is needed for one clay to be classified as better?
Line 70 How much of the growth media was transferred with the cells? Did author assess the impact of Se and Cu on ability of clays to remove dinoflagellates?
Line 72 Why were these two clays selected? Is Zeolite a ‘control’?
Line 74 see earlier comment about dissolving clays
Line 86-89 What did the three controls consist of? If have “different dilutions of clays added to the water, plus 10 mL of culture”, how does adding another 1 mL of water without clay constitute a control?
Line 90: How long was the overall experiment? Class added every 30 minutes? How many times?
Line 92 How was the interaction time selected? Was gentle mixing applied for flocculation? How long was the sedimentation? Is the proposed approach for use in a treatment plant or directly in the bay? Need to be specific. If it is for eventual use directly in the bay, how will 60 minute contact time be achieved?
Line 158 (and every other occurrence) If say ‘significant’ must include (p<0.05).
Line 159: Possible reasons why 0.25, 0.5, 1 and 4 only yielded significant removals with IW and SW. Why it did not occur with DW?
Line 185-86: Starting with ‘found between treatments’ implies all when it is only the 1.5 level. Please rewrite.
Line 217 why was 0.5 g/L used? Was is solely so that differences in cells could be seen?
Line 229 What is meant by ‘relatively more efficient’? would authors recommend its use? Why/why not?
Line 230 if aqueous medium is important, which had highest removal? If not the sea water then approach would not work in real scenario.
Line 235 If distilled water had best removal, what does it say about real application? What about sea water prevented effective removal?
Line 236-44 Were the removal efficiencies achieved high enough for the treatment to be considered effective?
Line 293 What is clay-prolonged contact cells’?
Line 298 What about the copper and selenium content (if any growth media transferred) impact on lysis?
Line 302-3 Without knowing flocculation rate/time or sedimentation time used in the experiments it is not clear that the study demonstrates this. Need to include the details.
Line 307-324 How do these results apply to your study?
Line 326 Need additional experimental details on the flocculation and sedimentation procedures before validity of conclusions can be assessed.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAuthors adequately addressed comments
Author Response
We appreciate your review. All suggestions have been incorporated. We've also increased the image resolution and added a graphical abstract.
