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After the efforts of the authors, they have responded appropriately to all reviewers' concerns and the quality of the manuscript is now ready for publication.
[# PeerJ Staff Note - this decision was reviewed and approved by Anastazia Banaszak, a PeerJ Section Editor covering this Section #]
As the reviewers commented, the quality of the manuscript has been substantially improved, but some minor further improvements are needed.
The revision improved in the highlight of the driving events.
In the M&M, dry weight was converted from volume according to equations of Wiebe 1988. However, the authors presented carbon biomass in the result. Please check what do you mean in biomass: dry weight or carbon biomass. Please also note, if you mean carbon biomass, to my experience, your value is much higher than I expected.
The data are valid.
No
As suggested by three reviewers, especially reviewers 2 and 3, this manuscript needs further revision and improvement. Most importantly, the manuscript is largely descriptive without a clear analytical focus. I hope the revised draft should make clear improvements in this regard.
[# PeerJ Staff Note: It is PeerJ policy that additional references suggested during the peer-review process should only be included if the authors are in agreement that they are relevant and useful #]
[# PeerJ Staff Note: Please ensure that all review and editorial comments are addressed in a response letter and any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate. #]
THe title is not good enough to express the contribution of the paper. Monitoring in the title should be deleted. Instead, the time period of 2005-2015 should be added.
The monitoring work is a regular work for zooplankton study.
The findings are well explained with some highlights such as increasing jellies and meroplankton.
long time monitoring of zoopankton is valuable to study climate change influence on marine plankton ecosystem. This monitoring site is valuable with narrow seasonal temperature range. I hope the coming monitoring will have good CTD data so that the authors could use salinity values.
This manuscript presents a valuable series of zooplankton on the Portuguese coast (Cascais Watch), covering an important geographic gap in the monitoring of plankton along the northern Iberian upwelling ecosystem. The overall aim is to assess key factors impacting marine populations. However, in its present version, the manuscript is largely descriptive without a clear analytical focus considering the current knowledge of the dynamics of zooplankton communities in the region. Because of the potential interest of this series in understanding recent changes in plankton communities in the North Atlantic, the manuscript must be better focused and organized by reformulating the objectives, rearranging the analysis, and improving the quality of figures as suggested in the next sections.
The analysis of the temporal patterns by quarters does not match the observed environmental variability, related to the upwelling dynamics. Alternatively, analysis taking into account upwelling vs. no-upwelling periods is suggested (see next sections for details). Similarly, the long-term variability is not adequately interpreted in view of recent knowledge of zooplankton community dynamics in this region (see the final section of this review)
The conclusions need to be rewritten after the new analysis.
The manuscript must be better focused and organized along the following lines:
1) The objectives of the study must be clearly formulated. For instance, other studies of zooplankton in this upwelling region described the seasonal change between upwelling and non-upwelling periods (e.g. Bode and Alvarez-Ossorio, 2004; Buttay et al., 2016), while studies in other areas of the NE Atlantic highlighted the role of transitional periods between stratified waters in summer and mixed waters in winter-related to the warming and cooling of surface waters (e.g. Valdés and Moral, 1998; Valdés et al., 2007). Thus, the study could try to examine whether the upwelling affects zooplankton communities more than seasonal warming. In fact, the monthly means of environmental variables shown in Fig. 2 indicate two main periods (i.e. upwelling and no upwelling) and do not support an analysis of zooplankton variables by quarters, as applied throughout the manuscript. In the case of long-term changes, recent studies in nearby sites have identified main shifts in zooplankton communities in the period covered by the Cascais Watch series: 2006 (Galicia: Buttay et al., 2016; Bode et al., 2020), 2008 (English Channel: Reygondeau et al., 2015), 2006, 2008, 2010, 2014 (Bay of Biscay, Dessier et al., 2018; Iriarte et al., 2022). Thus, the authors may try to assess if any of these shifts are supported by their data, even considering the lack of values for some years. Furthermore, the increasing prevalence of meroplankton in recent years aligns with similar changes observed in the North Sea (e.g. Djeghri et al., 2023) thus deserving a specific examination in this series (e.g. L 390-406)
2) As indicated above, the seasonal analysis may need to be reorganized by considering upwelling and no upwelling periods instead of quarters. Besides, the use of all the statistical tools described in section 2.1 must be better justified and supported by the corresponding results in tables (e.g. supplementary tables). Why use six different diversity indices when they show almost the same variability (Fig. S1)?
3) The numbering of figures is very confusing, with different numbering for the caption text and for the actual figure (e.g. Figure 2 in the PDF was then named Figure S1). Please revise this issue. Some Figures are difficult to understand. For instance, the correspondence of factor loadings and the zooplankton taxa cannot be appreciated because of the long variable names. Consider either using shorter labels (as in Fig. S3) or including the loadings in a Supplementary Table.
4) The impact of this research would be improved if the raw data of the series were made available through a web repository (e.g. PANGAEA)
Minor issues:
L 89: Indicate references supporting the expected “intensification of the upwelling events”
L 122: How many data points were retained for the final analysis?
L 134. Indicate the position of the center of the 1°x1° cell used for computation of the upwelling index. Also, specify whether the FNMOC or Meteogalicia model was used.
L 195 and through the manuscript: clarify the meaning of seasonal in the context of the study. In its present version “seasonal = quarterly”.
L 197-198: support these statements with the statistical results of ANOVAS and trend tests (e.g. in a Supplementary Table).
L 232-233; 407-409: expand the results on these ratios, as they seem to be one of the main findings of the analysis. Include also a brief justification for their use in the Methods section.
L 248: “depicted increasing trends” in Figs. 6 and S2. Are these trends significant?
L 438-533: This discussion focuses on meteorological seasons (= quarters) while most of the relevant variability seems related to the upwelling and primary production periods. Consider adapting the text to the analysis by upwelling – no upwelling periods. In addition, the comparison with other studies must consider whether the sites were (e.g. Galicia) or were not influenced by upwelling (e.g. southern Bay of Biscay).
L 550-555: Clarify the definition of the “two transition periods”: do you mean spring and autumn or upwelling – no upwelling?
L 581-804. Revise the spelling and format of references (e.g. L. 699 Kiørboe
Additional references:
Bode A, Álvarez M, García García LM, Louro MA, Nieto-Cid M, Ruíz-Villarreal M, Varela MM. 2020. Climate and local hydrography underlie recent regime shifts in plankton communities off Galicia (NW Spain). Oceans 1:181-197
Bode A, Alvarez-Ossorio MT. 2004. Taxonomic versus trophic structure of mesozooplankton: a seasonal study of species succession and stable carbon and nitrogen isotopes in a coastal upwelling ecosystem. ICES J Mar Sci 61:563-571
Buttay L, Miranda A, Casas G, González-Quirós R, Nogueira E. 2016. Long-term and seasonal zooplankton dynamics in the northwest Iberian shelf and its relationship with meteo-climatic and hydrographic variability. Journal of Plankton Research 38:106-121
Dessier A, Bustamante P, Chouvelon T, Huret M, Pagano M, Marquis E, Rousseaux F, Pignon-Mussaud C, Mornet F, Bréret M, Dupuy C. 2018. The spring mesozooplankton variability and its relationship with hydrobiological structure over year-to-year changes (2003 2013) in the southern Bay of Biscay (Northeast Atlantic). Progress in Oceanography 166:76-87
Djeghri N, Boyé A, Ostle C, Hélaouët P. 2023. Reinterpreting two regime shifts in North Sea plankton communities through the lens of functional traits. Global Ecology and Biogeography doi:10.1111/geb.13659
Reygondeau G, Molinero JC, Coombs S, MacKenzie BR, Bonnet D. 2015. Progressive changes in the Western English Channel foster a reorganization in the plankton food web. Progress in Oceanography 137:524-532
The authors have provided sufficient context and references to make the importance of this study clear in the introduction. The English is unclear in places, making it hard to follow what the authors are trying to say, and the Discussion could be restructured and made more concise in order to discern the significance and wider context of the main conclusions of this study. I was unable to assess the raw data since only seasonal means (supplementary table S1) or presence/absence data (online) is available. Figure 6 is hard to read, and I’m not sure is useful. I don’t agree that Fig 6a shows a decreasing trend in Appendicularia and Cirripedia as stated in the results (line 228-229). Figure 7 embedded in the manuscript file is impossible to read, but the version uploaded separately is different. Overall, I found the results in section 3.3. Zooplankton composition and interannual variability hard to visualise from the figures presented.
This manuscript presents a valuable original data set since continuing time series of zooplankton communities are rare despite their importance in identifying changes in ecosystems and assessing ecological status. The study is within the scope of this journal. The methods are largely described with enough detail, although I am unclear whether temporal autocorrelation has been accounted for within the DFA analyses. I did notice a couple of errors in the classifications presented in supplementary table S1. e.g. Oithona spp. has been listed as a calanoid, and Oncaea spp. and Coryceaus spp. have been listed as harpacticoids, when they should all be cyclopoids. Hopefully this is just a typo in the table and not a mistake in the data analyses since no cyclopoids are listed in the table, but the results describe a cyclopoid:calanoid ratio. I also wonder whether Oncaeidae and Corycaeidae might be more accurate taxonomies?
My main concern with this manuscript is that the authors have pushed the data analysis further than is warranted with the amount of data available. 10 years of data seems like a lot, but the Continuous Plankton Recorder Survey has shown that it is only sufficient to describe the variability of the data and discern seasonal dynamics (Edwards et al., 2010), which the authors have validly presented. About 20 years of data is required in order to start looking for interannual trends. At a minimum, I feel that the limitations of the interannual trends presented should be discussed further. The authors do state that ‘DFA is an adequate tool to explore patterns in time-series, especially those covering short temporal periods and comprised of nonstationary data (Zuur et al., 2003)’, however Zuur et al 2003 defines short time series as 15-25 years.
Some minor suggestions and comments are listed below:
Abstract:
- Line 28- Do you mean marine zooplankton populations, or marine ecosystems?
- Line 37-40- This sentence is very long and could be rewritten to make the meaning clearer.
- Line 48- should be ‘possible changes in the…’.
- Line 50- should be ‘trends in the…’.
Introduction:
- Line 62- Zooplankton is plural so should be ‘Zooplankton play a key role’ or ‘zooplankton play key roles’.
Materials and Methods:
- Line 124- Was it a single oblique tow? What speed was it deployed and hauled?
- Line 130- should be ‘analyses’.
- Line 139- What does ‘adding to circa 500 organisms’ mean? Do you mean you analysed splits containing about 500 organisms?
- Line 154- How did you identify influential taxa?
- Line 174- Did you pool all the Copepoda into one category, or for each copepod taxa separately? Which are the ‘relevant taxa’?
Results:
- Figure 3- It would make more sense to me if the white bars related to the left y-axis and the grey bars to the right y-axis.
- Line 196-197- Does ‘abundance differences were not significant’ relate to monthly or seasonal data, or both?
- Line 217- should be ‘found in the samples’.
- Line 237- what does ‘retained the first two components’ mean?
- Line 238- there are no correlations presented in Fig 7a, should this be worded differently?
- Line 245- it would be useful to put ‘common trends (CT)’ because I had forgotten what it meant when I got to this section.
- Line 260- Which abundance differences do you mean?
- Line 267 uses the Mann-Kendall abbreviation M-K but line 285 uses MK. They should be consistent with each other.
Discussion:
- Line 416-.What do you mean by large copepod? It depends which species of Centropages you are talking about, and what you are comparing to, e.g. Calanus or Paracalanus.
- Line 436-437- I doubt you get C. finmarchicus at your study site, so do you mean the northward expansion of C. helgolandicus could explain the observed decrease in Calanus spp.?
- Line 509- should be ‘is linked to’.
Conclusions
- Line 550-553- this result didn’t really come through in the results section.
References:
- Check references are in alphabetical order (see Vaz et al 2009.
- Line 699- should be Kiørboe.
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