Sargassum Biomass Movement and Proliferation in the Eastern Tropical Atlantic
, Jadu Dash 2, Emma Tompkins 2, Donatus Yaw Atiglo 3,4, Philip-Neri Jayson-Quashigah 5, Winnie Naa Adjorkor Sowah 6 and Kwasi Appeaning Addo 5Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsA very nice paper that helps people to understand the basis and severity of the problem. The methods and plots of results are solid. I suggest the problem of sargassum can be made into an opportunity, as discussed in Gray, L.A.; Bisonó León, A.G.; Rojas, F.E.; Veroneau, S.S. Slocum, A.H. “Caribbean-Wide, Negative Emissions Solution to Sargassum spp. Low-Cost Collection Device and Sustainable Disposal Method. Phycology 2021, 1, 49–75. https://doi.org/10.3390/phycology 1010004. Sargassum might be collected and then valorized into products. Can this be done in regions of interest to the authors? Please add a section on this before the Conclusions.
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Reviewer 2 Report
Comments and Suggestions for AuthorsVery good and interesting paper. I have only minor comments and questions.
- What is the logic behind the separation in the two regions? Are these regions sort of biogeographical regions?
- Line 235, give more detail about the Santer's method (2008). This method appears to be very complex and I don't understand how the AR component is added in the model.
- Figure 2: The ticks are the beginning of the years?
- Figure 2: The Wet Biomass ±1 SD is negative. It means that the used distribution is not correct. Perhaps it was Gaussian and Lognormal could be a better choice.
- line 338: correct "Accumulation"
- Figure 3: I don't understand why North biomass is larger than South whereas it is inverse in Figure 2. Please explain.
- In the co-variation analyses, the trend should be removed to detect co-variation. I am to sure that it was done.
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Reviewer 3 Report
Comments and Suggestions for AuthorsReview for the paper “Sargassum biomass movement and proliferation in the Eastern Tropical Atlantic” by Yanna Alexia Fidai, Jadu Dash, Emma Tompkins, D. Yaw Atiglo, Philip-Neri Jayson-Quashigah, Winnie Naa Adjorkor Sowah, Kwasi Appeaning Addo submitted to “Phycology”.
Pelagic sargassum blooms and their seasonal and annual trends in the Eastern Tropical Atlantic require additional studies because these blooms have had significant impacts on coastal communities, aquaculture, and biodiversity in this region, particularly since the notable event that began in 2011. The authors conducted a survey of remotely sensed data regarding the variability of sargassum influxes in West Africa and found that sargassum biomass typically peaks annually in September, with an additional increase occurring between March and May. Furthermore, the authors explored potential drivers of sargassum movement and proliferation by examining the co-variation of biomass with various atmospheric and oceanic factors, as well as policy changes affecting coastal management. They suggest that while sea surface temperature is a significant driver, other environmental and regulatory factors may also play a role in influencing sargassum dynamics. Such insights are crucial for stakeholders reliant on these coastal ecosystems, as they provide critical information regarding the timing and intensity of blooms. The results of this study may have important implications for coastal management and environmental policy in the Eastern Tropical Atlantic. Improved understanding of sargassum trends can empower local communities and governments to develop more effective strategies for mitigating the impacts of these blooms.
The paper is well-written but some issues should be clarified regarding methodology and data interpretation.
Abstract. This section is wordy and needs to be shortened to a limit of 200-250 words. The authors should focus on the main findings.
Introduction.
L 47-52. The authors should specify the environmental challenges that sargassum blooms pose to biodiversity and species population dynamics. What are the specific socio-economic challenges that coastal communities face due to sargassum blooms? Some examples or case studies would be useful.
L 56. Can the authors provide more infroamtion on valorization? What factors limit the valorization of sargassum into potential products?
L 76–79. The authors should clarify the geographic extent of the sargassum blooms mentioned in the text. In particular, they should specify how sargassum blooms differ in impact in regions such as the Caribbean, the Gulf of Mexico, and West Africa.
L 116-118. It would be useful to provide specific examples of how the United Nations Environmental Protection (UNEP) has categorised these factors into causal pathways.
L 134-135. The authors should indicate the spatial and temporal resolution required to effectively monitor sargassum blooms. How do current technologies fall short of this standard?
L 139-153. There is no need to separate this text into sections. It is part of the Introduction.
Materials and methods. Figure 1. The authors should add a coordinate grid to the map.
L 173-174. Can the authors provide some citations to support the statement that "the southern study area has lower sargassum biomass"?
L 206-207. What impact does excluding cloud-covered images (over 50%) have on the continuity and reliability of the results?
Results and Discussion.
L 283-284. Did the authors check their time series data for autocorrelation prior to analysis? How effective was the method chosen for linear regressions in dealing with this problem? Did the authors check the residuals for autocorrelation?
L 298-299. The authors should explain what factors contribute to the stark difference in biomass trends between the North and South study areas.
L 308-309. The authors should provide an explanation for these anomalous peaks.
L 310-311. Can the authors provide results of statistical comparisons or literature citations to support the assumption that the rainy season is a driver for this high biomass?
L 333-336. The authors should explain why the annual biomass accumulation in the Eastern Tropical Atlantic is not consistent with the Western Tropical Atlantic, as reported by Wang et al. (2018).
L 337. The authors should discuss the possible ecological or anthropogenic drivers for the statistically significant increase in biomass in the North study region. The authors should discuss how the seasonal variability in sargassum biomass overlaps with or impact fisheries, coastal ecosystems, and local communities in the North and South study areas.
L 382. The authors used a cross-correlation method to detect correlations between data sets, but this approach is not described in the corresponding section. In addition, correlation analysis of time series data often produces spurious correlations. What method was used to solve this problem? Figure A2 also shows a high correlation coefficient at the 7-month lag. Was this coefficient significant? If so, can the authors explain this finding?
What mechanisms could explain the significant 5-month lag between SST and biomass in the northern study area?
L 412. The authors mention "Pearson correlation", but this method without corrections is not appropriate for time-series data as it does not fix the autocorrelation problem. What might explain the statistically significant 6-month time lag between Saharan dust (AOD) and biomass in the South study area, and why is there no significant lag in the North?
As I can see in Figure A3, some correlation coefficients are very close to lag -6, for example at lag 0. Given the low p-value reported for lag -6, one can assume that these correlations were also significant. The authors should check the data.If sargassum growth peaks happen slightly earlier than Saharan dust peaks in the South, does this suggest a non-linear or indirect relationship between dust deposition and growth?
What role could the transport of sargassum from other regions (e.g., cooler waters) play in biomass variations in both the North and South study areas?
L 446. What mechanism explains the positive impact of iron on sargassum biomass?
L 497. Could the observed positive trend in minimum salinity correlate with sargassum growth more strongly than changes in mean or maximum salinity, and if so, why?
L 526-527. The authors concluded that the NAO index was not a significant driver, but the authors did not correlate this dataset with Sargassum biomass. Delayed data sets could result in significant correlations. Could indirect factors related to the NAO, such as wind-driven nutrient transport or ocean circulation, still play a role?
L 542. What specific mechanisms could delay the effect of volcanic eruptions on sargassum biomass? Could the iron inputs from eruptions have long-lasting impacts on nutrient cycles and algae growth?
L 571. The authors' statement is not supported by statistical comparisons because they did not use an appropriate statistical method.
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Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsI am not sure that removing the SD from figure 2 is the best strategy to hide that a wrong distribution model was used but it will not change the conclusions.
A part this problem, the authors answer correctly the questions.
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Reviewer 3 Report
Comments and Suggestions for AuthorsSecond review for the paper “Sargassum biomass movement and proliferation in the Eastern Tropical Atlantic” by Yanna Alexia Fidai, Jadu Dash, Emma Tompkins, D. Yaw Atiglo, Philip-Neri Jayson-Quashigah, Winnie Naa Adjorkor Sowah, Kwasi Appeaning Addo submitted to “Phycology”.
The authors have addressed my comments.
However, they should check the reference list for missing details (for example, L 810-811, 872-873).
They often use acronym "p." for article numbers, which is incorrect here.
The references and citations should be formatted according to the Instructions for authors.
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