Preliminary Microbiological Coastal Water Quality Determination along the Department of Atlántico (Colombia): Relationships with Beach Characteristics

Round 1

Reviewer 1 Report

The aim of this paper was to determine the microbiological quality (culture-based E. coli and real-time PCR Salmonella spp.) of beach water at 14 beaches along the Department of Atlántico (Colombia) and its’ relationship with beach characteristics as the presence of beach typology of beach facilities and streams outflowing into the coastline. The results show that E. coli was detected in the 70% and Salmonella spp. in 20% of samples. The highest E. coli concentration was observed at urban beaches with exception of Sabanilla. E. coli presence was associated with beach typology and the presence of facilities (bars, restaurants, kiosks) while Salmonella spp. with streams outflowing into the coastline lacking the wastewater treatment systems.

This article presents an interesting idea of a comprehensive analysis of microbiological water quality data. I find this very useful, given the often complexity of determining the cause of pollution. In my opinion, the main disadvantage of the work is the unsatisfactory number of samples (in some cases, at five locations, just one sample per location). Authors should take into consideration additional sampling in order to obtain sufficient quality for publication in this journal.

Specific comments:

65 → debris and poor water quality [10–14]

Please put a full stop.

73 – 75 → bacteria Escherichia coli, according to different environmental standards [18] as the ones established by the European Union Council (2006/7/EC and 98/83/EC) and the United States Protection Agency 75 (79 FR 10665)

Why you did not include data of intestinal enterococci? That is the main microbiological seawater indicator in the USA. I think that reference 18 is not adequate? Please include an appropriate reference.

„United States Environmental Protection Agency“ instead of „United States Protection Agency“

79 FR 10665 – National Primary Drinking Water Regulations. I consider that it is not advisable to compare the quality of recreational water with the drinking water criteria.

Could you please provide o brief description of recreational water legislation in Colombia? What indicators are being used? Are data about enterococci available? It would be interesting to show the values and relationships with enterococci. It has been considered as a key indicator for seawater.

83 → a limiting factor because beaches remain open to bathers during the sample and processing period

                        “and analytical processing period” instead “processing period”

116 → mm/year and mean temperature values are <27°C.

Could you please specify what is the mean air temperature? In this way, it is not informative enough, as the sign “<” can imply any value less than 27.

 

181 → E. coli analyses were performed according to ISO 16649-1:2013

• To my knowledge, it is an old version of the standard. There is a new version dating from 2018 (ISO 16649-1:2018)
• Additionally, please explain why did you use the standard method primarily intended to food analysis, when you can find existing water standard methods?

 

Microbiology of the food chain — Horizontal method for the enumeration of beta-glucuronidase-positive Escherichia coli — Part 1: Colony-count technique at 44 degrees C using membranes and 5-bromo-4-chloro-3-indolyl beta-D-glucuronide

 

• Have authors performed full validation to determine the characteristics of the method used for water samples?
• Authors stated that for E. coli determination Trypton-Galle-X-glucuronid (TBX) Agar was used. Could you please explain if you have used Mineral-modified glutamate agar (MMGA) as resuscitation medium? If not, please explain why?

193 → services [4]. The following categories were identified in this paper:

Please rephrase the sentence: The categories identified in this paper are described below.

246 → Real time PCR method allowed to detect the presence of Salmonella spp. in 20% of samples

Please, amended the sentence: Real time PCR method allowed to detect the presence of Salmonella spp. in 20% (6 out of 30) of samples

253 → expressed in cfu/100mL

Please, insert the space between 100 and mL.

256 → Regarding E. coli, 70% (21 out of 30) of samples presented this pathogen (Table 1).

“faecal indicator” instead “pathogen” would be here more appropriate term, considering the scope of the method.

260 → cfu/100mL

A space between 100 and mL is needed.

261 → presented the lowest E. coli counts with values between ˂1 and 7 cfu/100mL

A space between 100 and mL is needed.

262 → beach presented an average count of 32 cfu/100mL. According to the Directive 2006/7/CE

“2006/7/EC”, instead of “2006/7/CE”

264 → cfu/100mL

A space between 100 and mL is needed.

267 → percentage of samples complying Directive 2006/7/CE regarding E. coli concentration in seawater

“2006/7/EC”, instead of “2006/7/CE”

288 → counts between 21 and 51 cfu/100mL

A space between 100 and mL is needed.

292 → Beaches belonging to Cluster 2 presented E. coli counts between <1 and 7 cfu/100mL

A space between 100 and mL is needed.

300 → average values of E. coli with 248 cfu/100mL

A space between 100 and mL is needed.

303 – 304 → Table 2

3

Pto. Colombia Salgar

14

14

7

7

7

 

Please check the value of the percentage, I realized that the sum should be 14, not 21.

 

304 → were grouped. E. coli counts are expressed in cfu/100mL.

A space between 100 and mL is needed.

371 → value of 18 cfu/100ml and 33 cfu/100ml

A space between 100 and mL is needed.

374 → 2-1400 MNP/100mL

A space between 100 and mL is needed.

376 → cfu/100mL

A space between 100 and mL is needed.

378 → Puerto Velero) presented the lowest counts with values between 16 and 54 cfu/100mL.

A space between 100 and mL is needed.

381 → with the highest counts (262-352 cfu/mL).

Per mL or per 100 mL?

381 – 389 → Such differences may be related to E. coli survival time in sea water, i.e. the lapse time between the contamination event and the survey [32], that is the intermittent nature of this kind of contamination (i.e. the contamination source is not constant) as observed by Torres-Bejarano et al. [14] in Puerto Velero, or the different location of the sampled points. Additionally, Gram-negative bacteria lose quickly their ability to form colonies in seawater, although they can still be detected at high levels by viable counting methods [33] and that E. coli in seawater by effect of solar radiation can enter into a reversible state of "viable but not cultivable": this can strongly influence count values [34], explaining the differences observed at Sabanilla and the absence of any relationship between E. coli and the presence of streams.

Please further clarify the possible cause of the differences in the cfu numbers obtained for E. coli at Sabanilla beach in this study and the study conducted by Sánchez et al., regarding to "viable but not cultivable" (VNC) bacteria. In both studies cultivation methods was used, that detect only cultivable bacteria.

385 – 389 → Additionally, Gram-negative bacteria lose quickly their ability to form colonies in seawater, although they can still be detected at high levels by viable counting methods [33] and that E. coli in seawater by effect of solar radiation can enter into a reversible state of "viable but not cultivable": this can strongly influence count values [34], explaining the differences observed at Sabanilla and the absence of any relationship between E. coli and the presence of streams.

A space between 100 and mL is needed.

393 → cfu/100mL and 89% of the beaches investigated presented counts between 0 and 8 cfu/100mL

A space between 100 and mL is needed.

417 → sampling points (5, 6, 7, 11, 25 y 28)

“sampling points (5, 6, 7, 11, 25 and 28)” instead “sampling points (5, 6, 7, 11, 25 y 28)”

430 → between 648 and 1081 cfu/100mL

A space between 100 and mL is needed.

449 – 451 → Consequently, the combination of culture-based method to determine bacterial indicators and PCR to target waterborne pathogens can provide a wider overview for a complete assessment of beach water quality.

 

Do authors consider to use PCR methods to determine faecal indicators (E. coli and enterococci)?

 

475 → typology, explains the high E.coli

Please insert a space between E. and coli.

502 → Microbiological water quality is one of the most relevant reasons used by tourist to choose a beach and hence represents one of the most important components considered by Beach Awards. This aspect concerns also public health, which is evaluated internationally using faecal indicators as E. coli and Enterococcus faecalis.

I consider this sentence is an excess to the section “Conclusions”, as it is not based on the results of this research.

513 → Directive 2006/7/CE.

“2006/7/EC”, instead of “2006/7/CE”

 

 

Author Response

Dear Reviewer,

Thank you so much for your great work, observations and constructive suggestions, we greatly appreciated all of them. We clarified in the manuscript title that this is a preliminary investigation and we stated in the main text that further studies are needed in the future to have a more complex and accurate view on the microbiological water quality conditions of the area.

Please see detailed indications and answers to your questions in the file attached.

Thank you again for your work.

Best regards, Giorgio

Author Response File: Author Response.pdf

Reviewer 2 Report

JOURNAL

Journal of Marine Science and Engineering.

TITLE OF THE MANUSCRIPT

Microbiological water quality along the coast of the Department of Atlántico (Colombia): relationships with beach characteristics

 

REVIEW

 

MAIN GOALS

1. Determination of the microbiological quality (culture-based E. coli and real-time PCR Salmonella spp.) of beach water at 14 beaches along the Department of Atlántico (Colombia);
2. Determination of its’ relationship with beach characteristics as the presence of beach typology of beach facilities and streams outflowing into the coastline.

MAIN RESULTS:

1. E. coli was detected in the 70% and Salmonella spp. in 20% of samples.
2. The highest E. coli concentration was observed at urban beaches with exception of Sabanilla.
3. E. coli presence was associated with beach typology and the presence of facilities (bars, restaurants, kiosks)
4. Salmonella spp. presence was associated with streams outflowing into the coastline lacking the wastewater treatment systems.

 

GENERAL REMARKS:

The idea of broad analysis of microbiological seawater quality data is very interesting topic with practical implications. It is emphasized especially if taken into consideration how difficult is to deal with identification of the sources of pollution. This manuscript shows that authors are quite acquainted with the studied matrix, however, it needs to be emphasized that more attention should had be given to the sample number and representativeness. Concept of focusing the whole study to the presentation of the methodology that relies on the few and inadequate sampling is difficult to be considered seriously. As many researchers are interested to publish as much as possible, as quickly as possible, sometimes they act without all necessary reflection. Representative sampling as key empiric argument should had been carefully considered before the beginning of the study. Without it, all subsequent analytical work may be put in question for a serious scientific publication such as the Journal of Marine Science and Engineering.

It is needed the systematic checkup of typewriting and proper expression of numerous units that have been incorrectly given.

 

SPECIFIC COMMENTS:

Lines 27-29

Why did you deal only with E. coli and Salmonela spp. in this study? Why didn’t you analyze enterococci too as one of the main microbiological sea water indicators? What are the official seawater microbiological indicators in Colombia? Please, do consult and comment them according to the Colombian national decree for recreational waters.

Furthermore, one general remark, name “enterococci” should not begin with capital letter, since it is only the general group and not the Latin name of the family or genus.

Line 35

How can you claim that indication of management programs is obtained on the basis of such low number of samples furthermore lacking one of the most important indicators (enterococci)? Bear in mind that Salmonella spp. does not belongs to the enterococci group!

Lines 74-75

Authors should be careful in the use of the adequate legal acts as references. The use of old, therefore non valid acts (as EU regulation cited) cannot be advised. Furthermore, the names of legal rules should be properly cited (both EU and USA)! Proper citation is really one of the main requirements in preparation of the manuscript. Please update and amend!

Lines 91-95 (and throughout the text)

Authors should carry out more comprehensive crosscheck of the literature data dealing with the presence of Salmonella spp. in seawater. A more detailed review of the literature should be performed and referring to more recent papers than those used in this manuscript.

Lines 112-113

Representative (?) beach density of 14 beaches in 60 km? It is too low, especially when compared to the beach density used in the similar published studies (i.e. Italy, Greece, USA, Croatia, Portugal).

Line 116

It is not clear what does it mean <27°C?

Line 120

Authors should give additional information about sampling. What was the dynamics of sampling? What were the time intervals between sampling? What was the time of sampling? Hour? Morning? Afternoon?

Authors should consider that sunlight is one of the strongest bacterial reducers in the sea. Furthermore, the insulation affects significantly the cultivation potential of the bacteria what has been elaborated later on in this paper.  

Lines 121-126

This is the one of the main drawbacks of this paper. Consideration of obtaining the "indications to implement management programs" to be based on the total of only 30 seawater samples is not likely at all. In that regards, sampling should had been representative and, therefore, carried out in higher number per beach. And probably, on more beaches, if claiming to be the basis to above mentioned management programs. Furthermore, sampling is expected to be carried out during the regular intervals within the same season as well during the more than only one season. Representativeness of the samples is the premium, and the "conditio sine qua non" for every serious empiric study. Nonetheless the sophisticated analytical methods undergoing afterwards.

Authors should consider significant widening of the sampling in order to meet representative level of analytical pool.

All sampling was carried six years ago, in 2015. Did authors have more recent data (i.e. in the period 2016-2020) for the same beaches in order to make more representative crosscheck of the seawater safety on given portion of Colombian coast?

Lines 154-184

Authors applied two different analytical approaches for analysis of microbiological parameters in this study – detection (qualitative) of the Salmonella spp. by means of RT PCR and quantitative analysis of E. coli by membrane filtration method. Please explain why?

Did authors consider the use of the same analytical approach for both microbiological parameters? Why didn’t you take into the consideration to analyze enterococci, too?

In that regards, authors should have been more focused on more recent study of the same area published by Sánchez Moreno et. al. (2019), and cited in the manuscript, that deals with wider microbiological pool.

Line 181

Isn’t this standard (ISO 16649-1:2013) dealing with food analysis?

Lines 252-254

Apart of very low sample number (as commented earlier), sampling has been performed non-uniformly. What was the reason for not having equal number of samples for every beach? Authors should explain this!

Lines 303-304

Please check the numbers in the table 2.     

Lines 385-389

It has already been commented that insulation influences a lot the reduction of bacteria in seawater. Furthermore, it affects a lot if living bacteria is cultivable or not! This is one more reason for proper elaboration of sampling process (day, week, hour, season)! 

Lines 449-451

Comments given for the Lines 154-184 can be very appropriate for elaboration of this part of Discussion section.

Lines 501-539

Conclusions section is too long and it should be more concise! Please rewrite this section in order to have it clear and concise!

Author Response

Dear Reviewer,

Thank you so much for your great work, observations and constructive suggestions that allowed  to greatly improve the quality of the manuscript. We clarified in the manuscript title that this is a preliminary investigation and we stated in the main text that further studies are needed in the future to have a more complex and accurate view on the microbiological water quality conditions of the area.

Please see detailed answers to your questions in the file attached.

Thank you again for your work.

Best regards, Giorgio

Author Response File: Author Response.pdf

Reviewer 3 Report

the paper is unbalanced the introduction  part and the results presentation

however, although experimental design is not totally new, it helps to identify the health risk in areas heavily used for bathing where there are no historical series of monitoring of bathing water.

The method applied, as discusses by the authors, does not value a risk but only a potential passage of Samonella spp. in the water ecosystem this makes work weak but interesting against the areas application.

It would have been useful to compare exprerimental results from classic methodologies and indicators used in sector regulations to enhance the approach

 

it  would be useful to implement the discussion in wich the current methods and rules in force in various countries of the world  are compared. . To remember that bathing is commonly prohibited near the mouths of canals or rivers

Author Response

Dear Reviewer,

Thank you so much for your great work, observations and constructive suggestions.

Please see detailed answers to your questions in the file attached.

Thank you again for your work.

Best regards, Giorgio

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

 

the authors appreciated all the comments and has been significantly improved manuscript.

Therefore, I recommend the publishing of the manuscript in JMSE.

Reviewer 2 Report

Authors has taken into the consideration most of the comments and remarks given, improvements have been done.

The most important issue still remains – very few numbers of samples. Authors tried to explain it and they changed the title of the paper giving it the “preliminary” status. Well, with that in mind, it reflects more the true nature of the work done.

It is still an important drawback, however if considered it to be the baseline for further development of monitoring of seawater quality in Colombia it may be useful for scientific community to read about experiences worldwide.

Authors are encouraged for more detailed approach when further research will take place.