The reviewer judges that this manuscript has a relatively solid logical structure and interpretation of the results obtained. The overall description is written very clearly and concisely. On the other hand, there are some serious deficiencies in understanding the main idea of this manuscript, such as the lack of values in x-axes in Figure 5, one of the most important figures in this study. This is the main reason why the reviewer could not rate as a minor revision. The reviewer recommends revision of the manuscript by addressing following issues:

In Lines 70-73 and around: The description here is specific to oysters, while earlier in this paragraph shellfish is described in general. The reviewer would recommend the authors to add more explanation here as to why they focus or specialize on oysters among a variety of shellfish.

Line 251 and after: This paragraph belongs to Section 2.3, but the description seems to already include results. Therefore, the reviewer would recommend the authors to reconfigure the relevant contents, such as to move some statements here to Section 3.

Experimental design for future simulations: It would be normal to assume that an increase in atmospheric CO₂ concentration would be accompanied by an increase in atmospheric temperature associated with climate change. Therefore, the authors had better mention even briefly why they considered that it makes sense to add a scenario of “AtmCO₂”, i.e., simulated an increase in atmospheric CO₂ concentration but not an increase in air temperature.

Lines 323-324: Please refer to a figure which justifies this sentence, for example, to insert “(Fig. 5d)” after “… a minimum average of 1.1 in January”.

Fig. 5: The problem is that values in x-axes are all missing in each figure so we cannot figure out the exact time series. Please put the values in x-axes first. Also, any information about 27 ℃ in Fig. 5a should be added in the figure caption (the optimal temperature for oyster filtration).

Line 348: “Oyster growth metrics … are provided in Table 4.”: Please explain briefly what readers could learn from Table 4 here.

Line 363: “… throughout most of the region,”: Please refer to a relevant figure (Fig. 6f?) after this phrase so that readers could understand more clearly.

Line 367: Similarly, refer to Table S5 after the sentence of “TSS is projected ….”

Line374: The information of “the optimal temperature for oyster filtration (27 ℃)” should also be described in Fig. 5 caption.

Lines 376-377: Like the other part of main text, it would be more friendly to readers if the authors mention how much the bottom POC decreases in values in Tables 3 and S5.

Lines 388-390: “The greatest reduction in shell and tissue growth rates will ….”: The reviewer could not understand correctly what this sentence means based on the results obtained in this study. It might be partly because we cannot see the timing in Figure 5 because of no description of values in the x-axes (month/day). Please rephrase this sentence and modify Figure 5 thoroughly.

Figure 8: Please modify this figure by using colors that take universal design into consideration. There are many people that cannot distinguish between red and black, and perhaps between black and blue. To use different marks (open and dotted circles, triangles and so on) may be helpful as well.

Line 421: Please add description about shell thickness as well.

Line 431: “Predicted reductions in POC and O₂” --> “Predicted reductions in POC and/or O₂”?

Line 432: “(Table 3)” --> “(Tables 3, S5)”?

Line 439: “(Fig. 11b)” --> “(Figs. 7c, 11b)”?

Line 449: “(Fig. 10f)” --> “(Fig. 10d, f)”? Please confirm.

Line 450: “(Fig. 11c)” --> “(Fig. 11a-c)”

Line 452: “(Table 4; Fig. 11c, d)” --> “(Table 4; Fig. 11b-f)”? Please confirm.

Line 454: The exception seems to be for POC (Tables 3, S5) and O2 (Table S5) as well as for Ω_Ca. Please confirm.

Line 455: “... is identical to that of the Temp simulation.” Please refer to a relevant table (Table 4?) after this and/or the following sentence.

Line 456: Does not seem to be “slightly”. Please confirm.

Lines 469-480: Overall, statements in this paragraph are quite hard to understand. The fundamental problem is that the paragraph does not refer to relevant figures/tables or does not refer to them appropriately. To understand the first two sentences, relevant figures are necessary to be referred to. Also, Fig. 5 seems better to be cited in Line 480 (at the end of sentence) rather than in Line 479 to avoid confusion. Instead, a relevant figure should be referred to here.

Lines 476-477: “Total alkalinity, or buffering capacity, is also lower Rappahonnock than the lower York,”: How can readers verify this phrase? Could the authors add reference(s) or figure for readers to help comprehend this statement?

Line 524: “(Fig. 9c, 10c)”: Fig. 10c shows POC change, not oyster growth change. Please confirm.

Line 525: “(Fig. 6c)”: This figure shows results from Combined Future, not TMDL. Please confirm. At least the reviewer is not sure if his this comment is proper..

Line 538: “(Fig. 7a)” --> “(Fig. 5a)”?

Line 616: “(Fig. 7)” --> “(Fig. 5)”?

Previous modeling studies (e.g. Fujii et al., 2023) suggest that spawning season of oysters will be prolonged by climate change that may lead to lower quality of adult oysters and shorter time to market, as well as more severe conditions for oyster larva (as a relatively vulnerable stage to lower Ω_Ca in the future). The authors do not need to take this point into account in this study, but would be better to mention briefly somewhere, such as in Sections 4.4 and/or 5.

Figure S3: Highest and lowest values in the right y-axes in a and b are missing. Please revise.