Diatoms as Bark Epiphytes in the Tropical Lowlands of Panama

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Editor and Authors,

Thank you for the opportunity to review this manuscript. Overall, the study presents high-quality work and offers a valuable contribution to a niche yet important research area, in which comparable publications are exceptionally scarce. The investigation is carefully conducted and provides meaningful insights into bark-associated diatom assemblages in tropical forests.

My only substantial concern relates to the somewhat misleading title, which obscures the fact that part of the material was collected not from strictly terrestrial microhabitats but from the bases of tree trunks that are (periodically?) submerged. Consequently, the manuscript does not exclusively address terrestrial diatom taxa, but rather documents a gradient from terrestrial to aquatic communities associated with the same substrate. I therefore recommend revising the title and making this distinction more explicit within the text.

Author Response

My only substantial concern relates to the somewhat misleading title, which obscures the fact that part of the material was collected not from strictly terrestrial microhabitats but from the bases of tree trunks that are (periodically?) submerged. Consequently, the manuscript does not exclusively address terrestrial diatom taxa, but rather documents a gradient from terrestrial to aquatic communities associated with the same substrate. I therefore recommend revising the title and making this distinction more explicit within the text.

Thank you for the very positive reception of our paper. As far as your suggestion of a change in the title is concerned, we beg to disagree in regard to bark epiphyte – all our samples are bark samples. Possibly part of the problem is the term “forest”, because indeed Annona glabra is at the interface of forest and lake and thus not really part of the forest. We now changed the title to “Diatoms as Bark Epiphytes in the Tropical Lowlands of Panama”, which also is more precise in terms of location compared to the original title. Together with an additional, small change in the abstract we are really convinced that there cannot be any confusion about the “idea” of the paper any more.

Reviewer 2 Report

Comments and Suggestions for Authors

This study is a significant contribution to the study of epiphytic diatoms from the tree barks in Panamanian tropical forest. The authors 70 diatom taxa from 28 genera. Most taxa have been identified to the genus level only.

The "Introduction" is somewhat controversial. For instance, the authors cited two papers by Neustupa & Skaloud, and noted that diatoms had not been reported. However, the authors should take into account the differences in methods. Phycologist who studied epiphytic algae usually use cultures to reveal the species composition (see Neustupa & Skaloud 2008). Moreover, BBM is not the best medium for diatoms.

I think the following papers can be useful too:

https://doi.org/10.1111/j.1438-8677.1936.tb01946.x

https://doi.org/10.3390/d16010055 

Specific comments:

Figure 1. The micrographs are either too bright or too dark. The scale bars and arrows are hardly visible. I think the authors should mark Nitzschia and Achnanthidium in Figs. 1A,C or Nitzschia, Achnanthidium and Eunotia in Fig. 1D.

Figure 2A-C lack scale bars. Please, mark the Humidophila valves in Fig. 2A. Figs. 2B,C can be cropped.

Author Response

This study is a significant contribution to the study of epiphytic diatoms from the tree barks in Panamanian tropical forest. The authors 70 diatom taxa from 28 genera. Most taxa have been identified to the genus level only.

Thank you for this positive reception of our paper.

The "Introduction" is somewhat controversial. For instance, the authors cited two papers by Neustupa & Skaloud, and noted that diatoms had not been reported. However, the authors should take into account the differences in methods. Phycologist who studied epiphytic algae usually use cultures to reveal the species composition (see Neustupa & Skaloud 2008). Moreover, BBM is not the best medium for diatoms.

We fully agree that methodologies influence the outcome of a study. For example, we discuss in detail that we probably underestimate the occurrence of epiphytic diatoms at our study site because we sampled in the dry season. But this does not change the message of our study. Neither does a possible underestimate of diatoms in the study of Neustupa and colleagues. Thus, we would like to make no changes here.

I think the following papers can be useful too:

https://doi.org/10.1111/j.1438-8677.1936.tb01946.x

https://doi.org/10.3390/d16010055 

Thanks for pointing out these two papers. Obviously, there are more papers, but adding them does not change the interpretation. We did not comprehensively cite all sources that had some information on diatoms, but we are happy to add these two.

Specific comments:

Figure 1. The micrographs are either too bright or too dark. The scale bars and arrows are hardly visible. I think the authors should mark Nitzschia and Achnanthidium in Figs. 1A,C or Nitzschia, Achnanthidium and Eunotia in Fig. 1D.

Figure 2A-C lack scale bars. Please, mark the Humidophila valves in Fig. 2A. Figs. 2B,C can be cropped.

We modified the two Figures according to your suggestions.

Reviewer 3 Report

Comments and Suggestions for Authors

This is a very interesting paper on diatoms inhabiting tree bark. Please continue this line of research, as it has the potential to yield highly valuable and significant results. A few technical comments are included in the file.

Comments for author File: Comments.pdf

Author Response

This is a very interesting paper on diatoms inhabiting tree bark. Please continue this line of research, as it has the potential to yield highly valuable and significant results. A few technical comments are included in the file.

Thanks for the very positive reception. We have made the suggested changes in the ms.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have revised their manuscript. I recommend to accept it.