I struggled with the manuscript for many hours trying to figure out what the authors are saying, mainly because the presentation is very poor and very reader-unfriendly. My comments are divided into two categories:

Science:

1.I have followed Profs. Guo's and Zhang's work for years and have no doubt about Guo's modeling ability and the high quality data from Zhang's lab. The NPZD model, however, is a very simple one so ground-truthing is important. I failed to notice the comparison of field data and model results although clearly large discrepancies exist. It should also be said whether sea grasses or other plants on the bottom are important.

2.It is not clear why 70m was chosen as the lower limit of the SGD input. How the SGD discharge distributes within this 70m range was also not given.

3. For coastal modeling work frequently moving boundary is applied. I assume that the land boundary is not moving in this case because the tidal range is very small in the Japan Sea. It should be stated so.

4. Should explain the huge residual in Fig. 10.

5. Figures 8,9,11,12: not clear whether they are simply comparisons of SGD vs. rivers, or the ocean-side input is considered.

Presentation:

1. It is not even clear how much SGD contributes to the study area. It is said at several places that the SGD contributes slightly more nutrients than all rivers combined to the study area. Yet, line 169 says that ...the SGD mean value of DIN loading of 26.7 g/s ...is approximately 20% of total riverine nutrient loading. Only two lines above it is said that the SGD nutrient loading is the same as rivers.

2. Figure 10. There are many symbols to use. It is not possible to differentiate red circles from pink ones.

3. Line 433, Should use positive tone. Instead of saying that "we paid little attention to..." should say that seasonal and short term variations will be the focus of future work.

4. It would help the readers if the currents are plotted when horizontal distributions of parameters are provided.

Minor points:

1.Line 37 quotes Santos et al., 2021 as summarizing the SGD-related nutrient inputs. Wilson et al.(L&O Letters, 9,4,411,2024) gave a much more comprehensive summary.

2. Figure 1, state that the depth contours are in "m", and put "A, B, C, D" at the proper places.

3. Figures 4,7 and 8. The X-axis is distance, but from where?

4.Figure 6 is about phytoplankton but the color bar gives N.

5. Figures 7, 8, what is the unit for the color bar?

6. Figure 13, areas 1,2,3,4 should be A,B,C,D.

7. Line 586, "T"oyama "B"ay; should state (in Japanese).

Please see the uploaded review report