Acanthocephalan Worms Mitigate the Harmful Impacts of Heavy Metal Pollution on Their Fish Hosts
Round 1
Reviewer 1 Report
The manuscript by Hassanine and Al-Hasawi explores the potential beneficial impact of acanthocephalans on their fish host living in a highly polluted area. The authors also suggest the host-parasite system of Siganus rivulatus-Sclerocollum rubrimaris as a model for monitoring trace metal pollution. The overall originality/novelty doesn’t seem to be high as many studies before evidenced the bioaccumulation of trace metals by intestinal helminths from their fish hosts. Nevertheless, there is merit to the manuscript as it could have regional importance. The methodological approach seems appropriate to address this question, although it should be improved in some parts, especially the statistical analysis. The references are appropriate. Nevertheless, there are some serious issues that need to be addressed before the manuscript could be considered for publication.
INTRODUCTION
The introduction seems a bit too short and missing some information. The writing style is also problematic as most of the sentences are way too long and tiresome for the reader. These should be either shorten or divided into several shorter sentences.
Line 42 Please use histopathological instead of histological and histopathological.
Line 44-49 This sentence is way too long, please divide it into shorter sentences.
Line 49-53 This sentence is way too long, please divide it into shorter sentences.
Line 57-62 This sentence is way too long, please divide it into shorter sentences.
Line 56-64 This paragraph needs to be supplemented with additional information. Are all these biochemical parameters affected only by metal pollution, or other factors, e.g. presence of parasites, could affect them as well? Please indicate with appropriate references.
Line 65-73 It is not clear from this paragraph why this species was chosen for this study. Was it based on some previous studies? Is it economically important, easy to obtain, harbours acanthocephalans in contrast to other fish species or something else? Please be more specific.
Line 65-66 This sentence sounds as if the S. rubrimaris is the only parasite of S. rivulatus. Please rephrase or add information on other parasites if data is available.
MATERIALS AND METHODS
Although materials and methods are generally well described, there are some information missing. Also, some methodological procedures are not appropriate or completely missing. Furthermore, levels of liver enzymes and serum biochemistry clearly point out liver damage in contaminated fish. Have the authors considered performing liver histology to illustrate the extent of the damage in different fish groups tested? If not, please state the reasons for this.
Line 82 Please indicate as MEAN ± SD, not as a range.
Line 88 Same as for line 82
Line 91 What was the volume of the water sample? Please indicate.
Line 94 What was the volume of the blood samples taken? 6 mL to fill the vacutainer or less? Please indicate.
Line 103-105 Later in the results you mention prevalence and mean intensity of infection. How were these parameters calculated? Quantitative Parasitology is a neat software to calculate epidemiological parameters. Please add also mean abundance and indicate all these parameters with confidence intervals, not with standard deviation.
Line 103-105Were fish examined for any other metazoan parasites as well, as these can also have a systemic effect on the host’s health?
Line 105 20 worms from each infected host or 20 worms in total? Only 20 worms from about 3600 don’t seem representative at all as it is not even a single worm per host.
Line 119-123 Why were Cd and Pb chosen? Are these accepted as proxies for heavy metal pollution? Have the previous studies evidenced the presence of only these two metals? Or something else? Please specify. How many technical replicates were performed for each measurement? Please indicate.
Line 130-137 How many technical replicates were performed for each measurement? Please indicate.
Line 152-158 Later in the results you mention you found statistically significant differences for measured parameters between different fish groups. The numbers themselves are obvious, but what tests were used to test for these differences? Be mindful of the tests you use, as your sample is not particularly large. Please correct accordingly.
RESULTS
Results are generally a bit long with some superfluous sentences and need to be shortened to make them easily readable.
Line 160 Please use either cadmium and lead or Cd and Pb.
Line 174-180 Please indicate prevalence, mean abundance and mean intensity and use confidence intervals for these parameters, not the SD. You might want to consider putting these on a table.
Line 199-205 Same as in M&M, how was the difference tested to state it was significant?
Line 210-214 Same as in M&M, how was the difference tested to state it was significant?
Line 214-216 This belongs to the discussion or even conclusions. Please remove.
Line 226-228 Same as in M&M, how was the difference tested to state it was significant?
Line 230-232 This part is superfluous. Please remove.
Line 232-234 Same as in M&M, how was the difference tested to state it was significant?
Line 236- 237 This part is superfluous. Please remove.
Line 241-243 This part is superfluous. Please remove.
Line 243-244 Same as in M&M, how was the difference tested to state it was significant?
Line 246-247 This part is superfluous. Please remove.
Line 248-254 This part belongs to the discussion. Please remove.
Table 4. is not necessary for the main manuscript text. Please move it to supplementary data.
Figures 2., 3. And 4. Please consider adding coefficient R and p-value to the graphs.
DISCUSSION
The discussion is a bit too long and monotonous as several sentences are repetitive in different paragraphs. This section can be reduced by putting these sentences at the beginning of the part of the discussion dealing with biochemical parameters, as well as at the end. Also, the discussion should start with a short paragraph summarizing the main findings.
Line 374 Please use histopathological instead of histological and pathological.
Line 434-436 The manuscript deals with the harmful effects of trace metals pollution. What are the negative effects of elevated liver enzymes? These are evidently consequences of trace metal pollution. However, if you want to put it this way then you should also discuss how elevated liver enzyme values reflect fish health. Here seems to be the problem with the causality.
Line 446-448 This is a bit vague…what kind of parasites? Intestinal, ectoparasites…? Please specify.
Line 450-452 The manuscript deals with the harmful effects of trace metals pollution. What are the negative effects of elevated blood glucose? This is evidently a consequence of trace metal pollution. However, if you want to put it this way then you should also discuss how elevated blood glucose values reflect on fish health. Again, there seems to be a problem with the causality.
Line 465-467 Same as the previous comment.
Line 475-476 Again, this is a bit vague…what kind of parasites? Intestinal, ectoparasites…? Please specify.
Line 479-481 The manuscript deals with the harmful effects of trace metals pollution. What are the negative effects of reduced STP? This is evidently a consequence of trace metal pollution. However, if you want to put it this way then you should also discuss how reduced STP values reflect on fish health. Again, there seems to be a problem with the causality.
Line 495-497 Same as the previous comment.
Line 510-512 Same as the previous comment.
Lines 411-413; 440-442; 456-459; 470-471; 485-488; 501-503 All these sentences seem repetitive, just with different parameters. I would suggest summarizing these in a sentence or a short paragraph before line 411 and then continue discussing each parameter. This would reduce the length of the discussion and add to the clarity of the text.
Lines 437-439; 452-455; 467-469; 481-483; 497-500; 512-514 Similar as previous comment. All these lines are quite repetitive. I would suggest adding a short paragraph at the end of the discussion saying there is a negative relationship between the parasite infrapopulation size and levels of specific blood parameters. This would reduce the length of the discussion and add to the clarity of the text.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments for Author (s)
|
Instead of |
Put |
Line Number |
|
Infection |
Infestation |
10 |
|
After fish health |
As well as after fish consumers |
11 |
|
----------- |
Add heavy (before metal) |
12 |
|
contaminated |
Intoxicated |
15 |
|
mitigate |
Alleviates |
19 |
|
Impacts |
effects |
20 |
|
Sentinels |
Entry |
518 |
Line 42&43---histological and pathological changes such what ????----mention.
Line 33 ---What is the difference (s) between tissue damage and lesions ?
Line 36--some heavy metals were recorded higher percentage in the kidney -----Clear this and why ????
Line 66-73===must be removed and push to the abstract background
Line 125---contamination usually used for bacteria not heavy metal intoxication.
You must add table containing the permissible limits of heavy metals for the edible fish flesh (water also)
You must mention the method (s) you used for diagnosis of parasitic infestation .
Also ,if it is possible add stained slides for parasite and the examined liver
Line from 368-374----repeated.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have addressed all of my comments. I believe the manuscript text is significantly improved now and much easier to read, especially for the general readership. I would personally still move Table 4. to supplementary material as it contains raw data. However, if the authors' wish is to keep it in the main manuscript text, I have no objection to that.
Author Response
"Please see the attachment
Author Response File: Author Response.docx
