Seasonal Photoacclimation and Vulnerability Patterns in the Brown Macroalga Lessonia spicata (Ochrophyta)
, Claudio A. Sáez 1,2,†, Andrés Trabal 1,3, Félix L. Figueroa 4, Diego Pardo 1,2, Camilo Navarrete 1,2, Fernanda Rodríguez-Rojas 1,2, Fabiola Moenne 1,2 and Paula S. M. Celis-Plá 1,2,*Round 1
Reviewer 1 Report
An interesting and well-researched study of photosynthesis in the brown alga Lessonia. It brings together several strands of the ecology and physiology of this coastal species, supporting similar work in the area in relation to solar radiation levels, climate and seasonality.
Although the scientific content and its explanation are of a good standard, the MS was difficult to read and understand in places and the authors need to improve the text throughout for grammar and sentence construction.
Several sections, especially the abstract, introduction and discussion need to be reduced in length as they contain material that is not directly relevant to your study.
Particular points which need to be addressed are listed below by line number
1 Title. You need to provide authorities for the species you are dealing with , preferably in the title, after which they can be dropped.
Abstract. This is much too long. Remember that an abstract is meant to be a brief description of what you did and what you discovered.
120 The Beer-Lambert Law need only be cited, it is too well known to be included as an equation. Presumably the K value is in m-1 - not clearly stated initially.
133 delete growing
136 delete irradiance
139 estimated as
142 delete mathematical
144 from Schreiber
149 mg
151 g-values are more meaningful than rpm, the latter has little relevance, use a g value if you can find it for the centrifuge you used.
156 Not necessary to quote chlorophyll equations, just cite the relevant papers
168 90% methanol in water
253 Pearson [not Person]
264 Regarding the sea water transparency. You mention upwelling, does the reader thus assume that transparency is reduced in summer as a result of phytoplankton growth? You do not explain this fully though it is clearly important. This would clearly offset irradiance to algae such as Lessonia.
267-68 It would help to provide some relevant figures for coastal sea water in general at the latitude you were working at.
276 reduced reduce?
281 Cystoseira work needs a citation
Author Response
Reviewer # 1
An interesting and well-researched study of photosynthesis in the brown alga Lessonia. It brings together several strands of the ecology and physiology of this coastal species, supporting similar work in the area in relation to solar radiation levels, climate, and seasonality.
Although the scientific content and its explanation are of a good standard, the MS was difficult to read and understand in places and the authors need to improve the text throughout for grammar and sentence construction.
Several sections, especially the abstract, introduction and discussion need to be reduced in length as they contain material that is not directly relevant to your study.
Response: Thanks, all the comments and suggestions has been considered and included in this revision.
Particular points which need to be addressed are listed below by line number
- You need to provide authorities for the species you are dealing with, preferably in the title, after which they can be dropped.
Response: Thanks, we agree
Abstract. This is much too long. Remember that an abstract is meant to be a brief description of what you did and what you discovered.
Response: We agree, has been delete the extra information
120 The Beer-Lambert Law need only be cited, it is too well known to be included as an equation. Presumably the K value is in m-1 - not clearly stated initially.
Response: We delete the equation and clarify the units.
133 delete growing
Response: Done
136 delete irradiance
Response: Done
139 estimated as
Response: Done
142 delete mathematical
Response: Done
144 from Schreiber
Response: Done
149 mg
Response: Done
151 g-values are more meaningful than rpm, the latter has little relevance, use a g value if you can find it for the centrifuge you used.
Response: We agree and has been change the sentence
156 Not necessary to quote chlorophyll equations, just cite the relevant papers
Response: Done
168 90% methanol in water
Response: Done
253 Pearson [not Person]
Response: Thanks
264 Regarding the sea water transparency. You mention upwelling, does the reader thus assume that transparency is reduced in summer as a result of phytoplankton growth? You do not explain this fully though it is clearly important. This would clearly offset irradiance to algae such as Lessonia.
Response: Thanks, we agree, has been included the phrase with details.
267-68 It would help to provide some relevant figures for coastal sea water in general at the latitude you were working at.
Response: Thanks, we agree, has been included some values.
276 reduced reduce?
Response: Done
281 Cystoseira work needs a citation
Response: Done
Reviewer 2 Report
The interest of the study is mainly regional, justified by the lack of data or the Chilean coast, but the results may have also broad scale implications. The study is focused on the seasonal variability of a range of photophysiological and oxidative stress-related biochemical parameters, and shows a clear evidence for photoacclimation patterns. The results may be of interest, but the paper cannot be accepted in its present form, mainly due to the poor use of English language. I strongly advise the authors to have the manuscript thoroughly revised by a native English speaker.
A list of minor comments follows.
Title: The us of the ‘vulnerability’ should be better justified. The term ‘susceptibility’ is more often used, but normally in some specific context like ‘susceptibility to photoinhibition’
L49. Solar radiation comprised much more than visible and UVB radiation.
L67. Damage to the photosynthetic apparatus occurs not only in extreme conditions abut in virtually all light conditions.
L103. Were the algae intertidal? if not, at what depth were they located?
L110. When were the various abiotic parameters measured? At the time of sample collection?
L127. Please use the same notation, consistently.
L142. How good was the fit of the Eilers & Peeters model?
L146-147. The author used the model Eilers & Peeters to fit to NPQ vs E curves. this model was developed for PHOTOINHIBITION curves, can readily be applied to ETR vs E curves, but as far as I know, it is not appropriate to NPQ vs E curves. One reason is that NPQ vs E curves often show a accentuated sigmoidicity that the E&P model cannot follow. The model by Serodio & Lavaud (Photosyn Res 2011) was developed for NPQ vs E curves and has been used very successfully, should be used here too. I recommend applying it to the index Y(NPQ) (Klughammer & Schreiber 2008) and not to the (open scale) NPQ.
L193. Time of day of measurements? PAR should be given in umol/m2/s
L204. There is something wrong with Fig. 2, shows a black area not explained in the legend.
L207. I think it would be more logical to first show the raw data, light curves, etc and only then the association between different variables. It would be important to show the light curves, ETR and Y(NPQ).
L274. Decrease in Fv/Fm can indeed be due to photoinhibition, but the authors should be careful here. They should at least acknowledge that other causes may also induce a drop in Fv/Fm. One simple possibility is nutrient limitation.
L278. Also, associating ETR directly to ‘productivity’ may be far fetched, please acknowledge that ETR is a proxy, and many factors interfere in the relationship between ETR and photosynthetic rate.
L292. Maximum NPQ may be seen as an indication of the capacity for energy dissipation through reversible NPQ. But this depends on how reversible is the NPQ, which in turn depends on the light curve protocol used. It may well happen that part of this NPQ is slowly-reversible, associated to photoinhibition and not to energy dissipation. This should be acknowledged.
Author Response
Reviewer # 2
The interest of the study is mainly regional, justified by the lack of data or the Chilean coast, but the results may have also broad scale implications. The study is focused on the seasonal variability of a range of photophysiological and oxidative stress-related biochemical parameters and shows a clear evidence for photoacclimation patterns. The results may be of interest, but the paper cannot be accepted in its present form, mainly due to the poor use of English language. I strongly advise the authors to have the manuscript thoroughly revised by a native English speaker.
Response: Thanks, we include the suggests and has been changed the sentences respect to the comments.
A list of minor comments follows.
Title: The use of the ‘vulnerability’ should be better justified. The term ‘susceptibility’ is more often used, but normally in some specific context like ‘susceptibility to photoinhibition’
Response: Hence, in this research the vulnerability and capacity of acclimation to environmental stress related to Climate change mainly in Lessonia spicata are evaluated through to the effects of physical stressors as elevated irradiance of Photosynthetic active radiation, Ultraviolet radiation, temperature and abiotic parameters, along the one year with different levels.
The concept makes a reference that the possibility of the decrease of the photoinhibition, under increase of the solar irradiance in the seasonal patterns in autumn, winter, spring, and summertime. The evaluation the abiotic parameters; as temperature along to the year, provide information about the good or bad state of the algae, because these effects can be provoked to the effect in the distribution, growth, reproduction, among other.
- Andrews, S., Bennett, S., & Wernberg, T. (2014). Reproductive seasonality and early life temperature sensitivity reflect vulnerability of a seaweed undergoing range reduction. Marine Ecology Progress Series, 495, 119-129. These authors describe that the temperature is a major determinant of the performance and geographical ranges of marine species.
- Figueroa, F.L., Domínguez-González, B., and Korbee, N. (2014). Vulnerability and acclimation to increased UVB in the three intertidal macroalgae of different morpho-functional groups. Mar. Environ. Res. 97, 30-38. The authors shown that the solar irradiance, it is determinant for the accumulation of the photoprotective responses.
L49. Solar radiation comprised much more than visible and UVB radiation.
Response: Done
L67. Damage to the photosynthetic apparatus occurs not only in extreme conditions abut in virtually all light conditions.
Response: Done
L103. Were the algae intertidal? if not, at what depth were they located?
Response: Done
L110. When were the various abiotic parameters measured? At the time of sample collection?
Response: Yes, the abiotic parameters were measurements on the field at the same time of the sample collection. This information was included this information in the Table 1.
L127. Please use the same notation, consistently.
Response: Done
L142. How good was the fit of the Eilers & Peeters model?
Response: Yes, the fitting model used with in all data were calculated from the tangential model with an r = 0.98 ≈ 0.99 for the ETR vs E curves, and the fitting results were the r = 0.99 ≈ 0.97 for the NPQ vs E curves.
L146-147. The author used the model Eilers & Peeters to fit to NPQ vs E curves. this model was developed for PHOTOINHIBITION curves, can readily be applied to ETR vs E curves, but as far as I know, it is not appropriate to NPQ vs E curves. One reason is that NPQ vs E curves often show an accentuated sigmoidicity that the E&P model cannot follow. The model by Serodio & Lavaud (Photosyn Res 2011) was developed for NPQ vs E curves and has been used very successfully, should be used here too. I recommend applying it to the index Y(NPQ) (Klughammer & Schreiber 2008) and not to the (open scale) NPQ.
Response: We applied the tangential model reported by Eilers & Peters (1978) because we had tangential pattern of NPQ versus E. In the remarkably interesting paper by Serodio & Lavaud (2011) they showed different pattern of NPQ curves in the higher plant Arabidopsis thalian and in the diatom Nitzschia palea. In the case of A. thaliana grown ant high, moderate, and low irradiance not sigmoidicity was observed and thus Eilers & Peters model could be used. In contrast in the diatom N. palea at moderate and high irradiance clear sigmoidicity was observed and for these cases fitting considered the sigmoidicity was suggested by Seodio a& Lavaud (2011). However, at low irradiance as in A. thaliana, no sigmoidicity was observed, and in the diatom Eilers & Peters (1978) model could also be used.
Thus, due to the response of the NPQ versus E in pour study with Lessonia spicata did not show any sigmoidicity we applied the tangential model of Eilers & Peters (1978).
In any case we present the yield II, Y(NPQ) and Y(NO) as yield losses, versus irradiance in maximal and minimal values i.e., April (maximal) and July (minimal).
The yield of losses was calculated according to:
- Hendrickson L, Furnbank RT, Chow WS. 2004. A simple alternative approach to assessing the fate of absorbed light energy using chlorophyll fluorescence. Photosynthesis Research 82, 73-81.
- Kramer DM, Johson G, Kiirats O, Edwards GE. 2004. New fluorescence parameters for the determination of QA redox state and excitation energy fluxes. Photosynthesis Research 79, 209-218.
L193. Time of day of measurements? PAR should be given in umol/m2/s
Response: Done
L204. There is something wrong with Fig. 2, shows a black area not explained in the legend.
Response: Done
L207. I think it would be more logical to first show the raw data, light curves, etc and only then the association between different variables. It would be important to show the light curves, ETR and Y(NPQ).
Response: We have 12 Rapid light curves (with three replicated per time). To show the differences through the year we think that it is necessary to present the fluorescence parameters form the fitting of rapid light curves i.e., ETRmax, aETR, EK, ETR and NPQmax.
We maintain the figures with the fluorescence parameters, but we have added as example rapid light curves showing ETR, NPQ, YNO and YNPQ versus irradiance in maximal and minimal values i.e., April (maximal) and July (minimal). Thus, the readers can see the pattern of the above cited fluorescence parameters with the irradiance in two selected months with the explained criteria (maximal and minimal values)
L274. Decrease in Fv/Fm can indeed be due to photoinhibition, but the authors should be careful here. They should at least acknowledge that other causes may also induce a drop in Fv/Fm. One simple possibility is nutrient limitation.
Response: We agree, has been included a sentence with details
L278. Also, associating ETR directly to ‘productivity’ may be far fetched, please acknowledge that ETR is a proxy, and many factors interfere in the relationship between ETR and photosynthetic rate.
Response: Yes, we agree and has been include the word “index”
L292. Maximum NPQ may be seen as an indication of the capacity for energy dissipation through reversible NPQ. But this depends on how reversible is the NPQ, which in turn depends on the light curve protocol used. It may well happen that part of this NPQ is slowly-reversible, associated to photoinhibition and not to energy dissipation. This should be acknowledged.
Response: We agree, has been include the “associated to photoinhibition” in the paragraph
Round 2
Reviewer 2 Report
The authors have addressed most of my questions, and the manuscript is now clearly closer to being able to be accepted. I still have a few comments that I think should be addressed.
L40 What ‘three relevant band’ are the authors referring to? (‘bands’ not ‘band’). Again, it is not true that solar radiation is mainly PAR and UV: most of solar radiation reaching the Earth’s surface if infrared
L56-57 Please rephrase this sentence, the relationship between excess radiation and the tides in confusing
L135 Equation (2) is wrong. I believe the authors mean the NPQ index based on the Stern-Volmer equation
NPQ = (Fm-Fm')/Fm’
This NPQ index was first proposed by Bilger and Björkmann (1990), so please replace the two references. Why was this ‘open’ index still used, if the Y(NPQ) and Y(NO) were introduced? Y(NPQ) should replace NPQ is all instances.
L138. I have to insist that the Eilers & Peeters model (1988, not 1978) is not adequate to fit to NPQ vs E curves. It not the question that it happens to fit the particular NPQ vs E curves measured in this study – many other (even ‘empirical’) functions would easily do it. The question is that the E&P model is has a mechanistic nature for describing the variation of the rate of photosynthesis with light. Applying to NPQ curves is inherently nonsense. Also, being a model for NPQ vs E curves available and well established, it is hard to understand the authors decision.
Author Response
Reviewer #2
L40 What ‘three relevant band’ are the authors referring to? (‘bands’ not ‘band’). Again, it is not true that solar radiation is mainly PAR and UV: most of solar radiation reaching the Earth’s surface if infrared
Response: Done
L56-57 Please rephrase this sentence, the relationship between excess radiation and the tides in confusing
Response: Done
L135 Equation (2) is wrong. I believe the authors mean the NPQ index based on the Stern-Volmer equation
NPQ = (Fm-Fm')/Fm’
Response: Done
This NPQ index was first proposed by Bilger and Björkmann (1990), so please replace the two references. Why was this ‘open’ index still used, if the Y(NPQ) and Y(NO) were introduced? Y(NPQ) should replace NPQ is all instances.
Response: Done
L138. I have to insist that the Eilers & Peeters model (1988, not 1978) is not adequate to fit to NPQ vs E curves. It not the question that it happens to fit the particular NPQ vs E curves measured in this study – many other (even ‘empirical’) functions would easily do it. The question is that the E&P model is has a mechanistic nature for describing the variation of the rate of photosynthesis with light. Applying to NPQ curves is inherently nonsense. Also, being a model for NPQ vs E curves available and well established, it is hard to understand the authors decision.
Response: Indeed, all the photosynthesis curve settings have been set for photosynthesis curves for oxygen, carbon, or ETR versus light and not for the NPQ. What we do is use the mathematical model because the curve adjusts to this and shows us parameters are analogous to those that come out of the ETR vs intensity curve, that is, the NPQmax, the slope (alpha NPQ), and the saturation irradiance of NPQ. This is valid because the NPQ was not sigmoidal (please see Figure 4B), the trajectory of the curve was like that of ETR. We could use also a Michaelian adjustment to adjust photosynthesis as it is an enzymatic process because NPQ is also indirectly associated with enzymatic relationships, but we can also use other settings such as the Hyperbolic tangent fitting models according to Ritchie 2008. In this case, we have used it and the responses have been remarkably similar (see Figure 7).
- Ritchie, R. J. (2008). Fitting light saturation curves measured using modulated fluorometry. Photosynthesis Research, 96(3), 201-215.
