Temporal Evolution of Diatoms in a Temporary Pond Situated in the Massif du Sancy Mountains (Massif Central, France) and Description of a New Pinnularia Species
, Elisabeth Allain 1, Olivier Voldoire 1, Carlos E. Wetzel 2, Luc Ector 2 and Bart Van de Vijver 3,4
Round 1
Reviewer 1 Report
This study presents interesting findings about the dynamic changes in the diatom community in a high mountain pond in central France. These changes are driven by large changes in environmental conditions from the pristine and dilute conditions associated with snowmelt to eutrophic conditions in late summer following the impacts of cattle grazing. The 3-year study was well designed and the results are comprehensive. Given the impact of climate change on high mountain environments and the apparent decision to remove cattle grazing, these results will be of particular interest in the future.
Another important strength and interesting aspect of this study is the thorough description of a new species of Pinnularia that is a significant member of the diatom community of this pond. If changes in the diatom community occur in the future, having a definitive description of this species will be important for documenting and understanding the change in the pond ecosystem. The authors could expand the discussion to point this out more explicitly.
The manuscript is well organized and the results are generally clearly presented. The discussion of the nutrient cycling (lines 340-368) could be clarified by addressing the low concentrations of phosphate relative to ammonium and nitrate for most of the study period. For the two dates when phosphate concentrations were above detection it would be worthwhile to consider the N:P ratio and the implications for diatom growth and the potential causes of high ammonium concentrations.
The figures are generally clearly presented. The authors may consider revising Figure 30 to not show the evenness values on the same scale as the Shannon-Wiener diversity values, because the range of evenness is much less than that for diversity. One approach would be to stack the separate graphs, rather than putting all 3 metrics on the same graph.
There are a number of edits that the authors could consider that would help clarify the text, as noted below in reference to the line numbers:
Line 20- replace “since” with “between” and revise to “Water samples and..”
Line 22- replace “few” with “poorly”
Line 24- replace “since” with “beginning in”
Line 25- replace “At” with “During” and revise to “the dominant species were Nitzschia…”
Line 35- replace “accidental” with “episodic”
Line 53- suggest revising to “conservation of diatom biodiversity”
Line 54- delete “few”
Line 56- revise to “have been conducted for this type of pond”
Line 61- replace “actual” with “current” and revise to “to inform future management plans by documenting the consequences…”
Line 79- replace “its” with “this”
Lines 85- 86- revise to “cattle that use this pond as a dinking place and as a result heavily trample half of its surface..”
Line 89- this should be labelled “Figure 2”
Line 94- delete “also”
Line 104- change to “precipitation event”
Line 107- revise to “only a little water”
Line 134- replace “retained” with “determined”
Line 136- replace “done” with “placed”
Line 148- replace “retained” with “considered”
Line 156- revise to “without the July 2018 sample”
Line 159- replace “At” with “During”
Line 162- revise to “cattle were present at the pond”
Line 176- revise to “nitrate”
Line 256- replace “being” with “as”
Line 257-258- clarify meaning of “typical” given that the species were absent in other samples
Line 299- revise to “cattle are..”
Line 306- revise to “allowed not only the assessment of the diatom…”
Line 307- revise to “but also documented the impact..”
Line 352- replace “few” with “limited”
Line 360- replace with “the re-impoundment could have resuspended the particle in the ..’
Line 385- revise to “contributed to completing..”
Line 407- revise to “was to support the removal of the cattle..”
Author Response
- A paragraph has be added on the interest of describing the new Pinnularia. Thank you to suggest it.
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The discussion of the nutrient cycling (lines 340-368) has been reworked and a paragraph has been added. For the ammonium, the two principal hypothesis were already written.
- The Figure 30 was reworked and Evenness was separated from S-W diversity and the number of species.
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All the suggestions were taken into account and the revision was done.
Line 257-258- I delete the word as it was a mistake.
Reviewer 2 Report
Water sample and diatoms were collected in a temporary pond and the diatom composition and diversity were recorded with water quality parameters. A new diatom specie of the genus Pinnularia were reported in this manuscript. This work would help us get insight into the diatom information in the temporary waterbody. It is worthy to be accepted after minor revision.
1.progress of algal composition and diversity in the temporary waterbody should be mentioned in the Introduction section.
2.Figure 4, figure 30, Figure 32 and figure 33 is poor quality and need to be polished.
3.The new species should be highlight its different structure from the other genus Pinnularia and make a decision that it is a new one based on the literature examination.
Author Response
1- A paragraph has be added on the progress added by this study onf algal composition and diversity in temporary waterbody. Thank you to suggest it.
2- All the figures were reworked and registered into. tif to improve the quality.
3- We are not sure how to interpret this question. In the text, the new species was compared with similar Pinnularia species worldwide and morphological details regarding these differences were highlighted. Based on this morphological comparison, we justified its description as a new species.
