Mapping Selected Emergent Marine Toxin-Producing Organisms Using Historical Samples with Two Methods (Biosensors and Real-Time PCR): A Comparison of Resolution

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Recommendation for Minor Revision on Manuscript Titled ''Mapping selected emergent marine toxin producing organisms using historical data sets with two methods (biosensors and real-time PCR): A comparison of resolution''

        This study focuses on using biosensor technology to analyze Continuous Plankton Recorder (CPR) samples collected around the Iberian Peninsula, aimed at identifying harmful algal bloom (HAB) species. It highlights the use of biosensor analysis to successfully identify a range of algae, including Pseudo-nitzschia spp., Prorocentrum lima, Alexandrium spp., Gambierdiscus spp., and Coolia spp., from samples preserved for up to nine years. This method demonstrates advantages over traditional RT-PCR techniques, particularly in dealing with long-term preserved samples and degraded DNA. The innovation lies in the application of biosensor technology, which enhances detection sensitivity and reduces costs, while enabling the analysis of long-stored samples. Additionally, the study reveals the impact of climate change on the south-north migration patterns of microalgae, providing new insights into plankton dynamics and responses to environmental changes.

However, the research has its limitations. Given these observations, I would recommend a minor revision. The paper is innovative and contributes to the field, but addressing the mentioned limitations and concerns.

 

Comment1:

The abstract effectively summarizes the study's methodology and findings but lacks specificity in elucidating the significance of detecting tropical toxic dinoflagellates like Gambierdiscus and Coolia off the Iberian Peninsula. I recommend clarifying how this discovery contributes to understanding algal distribution patterns under climate change. Additionally, the abstract should briefly address the study's limitations, such as potential biases in sample collection or challenges in interpreting biosensor data.

Suggestion: Amend the abstract by adding a sentence or two specifically highlighting the importance of finding these tropical toxic dinoflagellates in the context of climate change impacts on algal distribution. Also, briefly mention the limitations that might arise from the methods of sample preservation and processing used in this study.

Comment2:

The introduction provides detailed background information on the Continuous Plankton Recorder survey, but it inadequately discusses the impact of formalin preservation on DNA quality and its implications for molecular analysis. Given its crucial role in your study, I suggest expanding on this aspect.

Suggestion: Enhance the introduction by adding a discussion on how formalin affects DNA quality and why this is critically important for the molecular analysis in this study. Additionally, outline how recent advancements in DNA extraction and PCR technology have addressed the challenges of working with formalin-preserved samples.

Comment3:

The results section effectively presents findings from the biosensor analysis, but it lacks a comprehensive discussion on the implications of the observed distribution patterns, especially the northward increase of Pseudo-nitzschia small cells. Furthermore, the limitations of the study, such as the inability to quantify cell numbers from DNA data and the potential for false negatives in the samples, are not adequately addressed.

Suggestion: Expand the results section to include a detailed interpretation of the distribution patterns observed, particularly for Pseudo-nitzschia small cells. Also, include a discussion on the study's limitations, such as challenges in quantifying cell numbers from DNA data and the possibility of false negatives in biosensor analysis.

Comments on the Quality of English Language

Writing and Grammar:

The manuscript contains some grammatical errors in the paper, thorough proofreading is recommended to improve the readability.

Author Response

please see attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This short note explores where more could be done with archived formalin-preserved continuous plankton recorder (CPR) silks, already examined by low-magnification microscopy , by also applying biosensor methods. RT-CPR did not perform well with highly degraded DNA.  While the number of samples examined (11 silks from a cruise track close to the Iberian Peninsula) and the species targets examined (Alexandrium, Prorocentrum, Coolia, Gambierdiscus, Pseudio-nitzschia) are limited, the biosensor results look promising and well worth further pursuing.

Minor editorial comments:

"continuous plankton recorder silks" needs to be in the title. These are not data sets, but archived samples.

line 13. degrade 

line 15. nine=9 as in line 14

line 27. has= the CPR survey comprises...

lines 27-42 appear to to be repetition of the first part of the abstract. DELETE?

line 47. SAHFOS is the institution that runs the CPR survey. Not "previously called"

Table 1. When 7m=7 months, and 9y=9 years; one month should be "1m" (not 0m). Correct throughout

Table 4.  "canariensis" is misspelled (not canaryensis). Correct throughout

Line 299, table 4. "arenysensis" is misspelled (not arenyensis ; but OK on line 325)

Line 304. I query the identification of Prorocentrum "exuviella" type. Unless in very shallow waters with resuspended benthic P. lima (but the CPR operates in offshore deeper waters), this unlikely is P.lima but could be P. compressum?. Species identification by microscopy of cells embedded on silks is very imprecise. The statement "Exuviella lima is a synonym of Prorocentrum lima" is misleading in this context.

Fig.3, 5.  Pseudo-nitzschia (not Pseudo-Nitzschia); correct canaryensis, arenyensis

line 365. spring (lower case)

line 373. Peninsula

line 383. bottom

Line 376. The detection of Gambierdiscus, indeed most likely on rafting seaweeds is the most interesting

line 395. "who" refers to persons; this should be "which"

line 396. They=these authors

line 400. they= Ramilo et al 

line 404. Does the detection of Gambierdiscus DNA by biosensor automatically mean that these were viable living cells? How long can DNA persist embedded in seaweed detritus?

line 422. hybridisation with electrochemical detection is a powerful and useful tool; this is repetition of line 415

line 419, 426. specify the costs!

line 431. forms =taxa; "and" =?including the genus Gambierdiscus. Some species also occur in temperate and subtropical waters, not always tropical.

464.good ship=?cargo ship

line 434. is the same=?correlated with that detected by RT_PCR

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Minor corrections, as suggested.

Author Response

please see the attachment

Author Response File: Author Response.pdf