Observed and projected impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: A case study in the Hinase Area, Okayama Prefecture and Shizugawa Bay, Miyagi Prefecture, Japan
Abstract. Coastal warming, acidification, and deoxygenation are progressing, primarily due to the increase in anthropogenic CO2. Coastal acidification has been reported to have effects that are expected to become more severe as acidification progresses, including inhibiting formation of the shells of calcifying organisms such as shellfish. However, compared to water temperature, an indicator of coastal warming, spatiotemporal variations in acidification and deoxygenation indicators such as pH, aragonite saturation state (Ωarag), and dissolved oxygen in coastal areas of Japan have not been observed and projected. Moreover, many species of shellfish are important fisheries resources, including Pacific oyster (Crassostrea gigas). Therefore, there is concern regarding the future combined impacts of coastal warming, acidification, and deoxygenation on Pacific oyster farming, necessitating evaluation of current and future impacts to facilitate mitigation measures. We deployed continuous monitoring systems for coastal warming, acidification, and deoxygenation in the Hinase area of Okayama Prefecture and Shizugawa Bay in Miyagi Prefecture, Japan. In Hinase, the Ωarag value was often lower than the critical level of acidification for Pacific oyster larvae, although no impact of acidification on larvae was identified by microscopy examination. Oyster larvae are anticipated to be affected more seriously by the combined impacts of coastal warming and acidification, with lower pH and Ωarag values and a prolonged spawning period, which may shorten the oyster shipping period and lower the quality of oysters. No significant future impact of surface-water deoxygenation on Pacific oysters was identified. To minimize the impacts of coastal warming and acidification on Pacific oyster and related local industries, cutting CO2 emissions is mandatory, but adaptation measures such as regulation of freshwater and organic matter inflow from rivers and changes in the form of oyster farming practiced locally might also be required.
Masahiko Fujii et al.
Status: final response (author comments only)
CC1: 'Comment on bg-2022-223', miho ishizu, 02 Dec 2022
- AC1: 'Reply on CC1', Masahiko Fujii, 20 Mar 2023
RC1: 'Comment on bg-2022-223', Anonymous Referee #1, 21 Dec 2022
- AC3: 'Reply on RC1', Masahiko Fujii, 20 Mar 2023
RC2: 'Comment on bg-2022-223', Anonymous Referee #2, 06 Mar 2023
- AC2: 'Reply on RC2', Masahiko Fujii, 20 Mar 2023
- EC1: 'Comment on bg-2022-223', Tyler Cyronak, 21 Mar 2023
- EC2: 'Comment on bg-2022-223', Tyler Cyronak, 21 Mar 2023
Masahiko Fujii et al.
Masahiko Fujii et al.
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This study mentioned about the development of continuous monitoring systems for coastal warming, acidification and deoxygenation in the local areas in Japan by observation and modeling. In addition, they try to project the future situation under the IPCC scenario.
Reading through this manuscript, I thought that the volumes of each section are unbalanced. Especially, the volume for the result section is too short, compared to the volumes of introductions and methods.
I believe that one of the highlights in this study is to develop the model for the specific coastal area. Therefore it would be better to add more analysis by using the model outputs to show how their model is reproduced well in this target coastal area. At that time, seasonal horizontal distributions of each variable could be useful with comparison of the other observational data. Probably DIC and ALK are probably difficult to be got horizontally, but temperature and salinity, oxygen data could be available if you try to find in Japan. These improvements could make you deepen for your understanding of the model, which will make useful for your future study.
The sentence of the abstract should be blushed up. The current abstract was not a self-contained summary of your work. Method, how to examine and what you found should be included. The sentence “Coastal warming, acidification, … to facilitate mitigation measures” can be shorten. The sentence “To minimize… oyster farming practiced locally might also be required” is not necessary.
After revising the manuscript, I suggest you reconsider the title. The current title does not reflect the content of the current manuscript.
The sentences are too long. The sentence can be shorter. The current manuscript is divided into 5 sections (1.1, ~ 1.5), but I think it would be better to write it all in one. When you improve the manuscript, you also think about the balance of the volumes in the section. The volume of the introduction is heavy compared to the results, discussion and conclusion sections.
2.1 Study sites:
This section is also too heavy, compared to the results, discussion and conclusion sections.
3.1 Observed results:
The current version has been divided the section into 3.1.1~3.l.7, but you don’t need to divide individually. Please reconsider this part.
3.2 Modeling results:
The results of the numerical models are necessary. Please put additional analysis such as horizontal distributions and so on to show how the model reproduces in this target area horizontally and timely.
Section 3.2.2 Future projection:
This section is a discussion matter. This part can be moved to the discussion section if you add analyses of the model reproducibility.
The section 4.2, 4.2.1 and 4.2.2 can be moved to the conclusion section. Please reconsider your construction.
Please add references after the sentence (Extreme events such as severe…intensely in the future) in page 16.
The conclusion should be improved. Basic conclusion includes the purpose, the summary of this study and self-evaluation/prospects.
The information of latitude and longitudes are necessary. Right figures are not appropriate in scientific papers. I think that making an original map by yourself is necessary. In that case, Japanese character should not be included in your map. Right figure is relatively too small.