The authors presented a set of incubation experiments using vegetated and unvegetated sediment cores and explored production, respiration, and carbonate precipitation and dissolution rates for these two type of environments. Their general conclusions are as expected, i.e., seagrass vegetation enhances organic carbonate production along with net calcification, compared with bare sediments.

The manuscript is largely well written and easy to comprehend. The only major comment I have is with the way statistics is presented. It is unclear why the authors chose to report standard error instead of standard deviation for these replicate core incubations. Is the purpose to reduce the size of the error bar? I would report standard deviations instead to show variability.  There are also some confusions with how the two set of incubations are compared, please see detailed comments below.

The graphic abstract is inconsistent with abstract "… resulting in no significant difference in NEC between SG and BS”. But in the graphic abstract, NEC = 10.9 and -2.3 in SG and BS sediments.

Section 2.5, need to spell out assumptions for using short durations (a few hours) to estimate daily rates.

L102, add citation for Coral Allen Atlas

L141, change “checker” to “sonde”

L163, change “difference” to “sum”, adding respiration rate and NPP to get GPP.

L175, state the duration of alkalinity difference measurements

L205-207, suggest removing this sentence, otherwise worsening OA at night needs to be included.

L234-235, show the data.

Fig. 5, use the same y-axis unit to avoid confusion

L287, reword to “when GPP is lower”.

Table 1, why not use the same unit to facilitate comparisons?

Fig. 7, need error bars

L356, remove “shoot density” or change to high shoot density and root biomass.

L383, but earlier in the text (L216), Ω between the two sets are not significantly different, which contradict with L213 however.

L391-392, with NEC much different, why alkalinity fluxes are similar? Or is it because the variations are larger than the difference of the means?

L396-397, note the cited study use a seawater that may or may not be the same as the seawater in your case, so it is useful to do some calculation.

 Natividad and others explore the carbon balance and metabolism of a restored seagrass meadow. The analysis is largely interesting and methods sound, but a number of aspects of the presentation need to be improved and I have concerns about how the in situ results are translated to the real world environment.

Graphical abstract: units are needed on some terms (namely calcification).

41: are there 72 species globally? Are species-level differences relevant here? Does this apply to just the grasses?

145: did this reflect the PAR making it to the grasses in the natural environment with a larger water column on the order of 2-4 m? (see also line 197 and elsewhere). This feeds into the explanation on line 305: is PAR actually higher at leaf level in situ?

a bit critical of using hours for measurements because this is not an SI unit. Aggregating to days is a different story because this is an aggregation. I know that the community often uses hours, but a lot can happen in an hour. Perhaps note that these units are to compare against other studies.

Fig. 3: does this pass a colorblindness check? At a minimum use differently shaped symbols. Also Fig. 4. And especially Figure 8. This figure would not be interpretable if printed in black and white, and not everyone has a color printer.

From the discussion, why is R suppressed in the seagrass ecosystem? The full mechanisms might be clear but it's important to explain what is happening to the best that the data will allow.