A Global Assessment of the Potential for Ocean-Driven Transport in Hatchling Sea Turtles

Round 1

Reviewer 1 Report

Dear Authors,

I enjoyed reading the manuscript that I believe will certainly be of interest to the readers of Waters. It is well organized, sufficiently concise and clearly written. The global analysis of the physical factors that influence hatchling dispersal during the first month of life provides some interesting results and is definitively worth to be published. However, I think that you should be clear all through the text that what you are analysing and discussing is “the environmental setting into which turtles disperse” (page 2, lines 92-93) and not the effective hatchling dispersal because you did not consider swimming and, as you stated at page 2 lines 90-91, “swimming by sea turtles at this stage can have important implications for movements, distribution, and survival”.

I made a few comments that I hope will help to further improve this well done work.

1. Page 3, lines 108-109: I believe it would be useful if you provide, at least as supplementary information, the coordinates of each nesting location you selected for the simulation and the distance from the coasts of each release site. Was this always the same for all the nesting sites considered?
2. Table 1: I suggest to rearrange the table, ordering the columns first by ocean region and then alphabetically by country.
3. Table 1: I would add the measurement unit (km) in the last column (mean distance ± SD)
4. Figures 2B, 4B and 4F: Check the measurement unit on the y-axis which is not km because you transformed the values into squared roots
5. Figure 4: The figure caption refers to the standard deviation of transport distance, yet on the Y-axis “mean transport distance” is indicated, I suggest to add “SD” to the y-axis title for consistency
6. Page 13, lines 246-247: Is the increase in the variability in dispersal distance with the dispersal period not expected because mean dispersal distance increases with period?
7. Page 13, line 255: The Red Sea had the “lowest” mean transport (Fig. 2). Please correct.
8. Page 13, line 255: Transport distances are shown in Fig. 2, please add this reference.
9. Page 13, lines 266-272. Results presented here provide evidences that the environmental setting into which turtles disperse is highly variable but how this translates into the actual hatchling offshore transport and related survival is not straightforward for the reason you cited in your introduction (page 2 lines 90-91). Higher predation is expected as hatchling swim through the dangerous and shallow water of the continental shelf but once they have reached the relative safety of the open sea, they must find suitable offshore developmental habitats in order to survive and this, depending on the ocean region, may not be necessarily related to the straight dispersal distance from the nesting beach. To this respect, I believe it would be interesting to calculate the time required to reach offshore waters. Could you add such data to the results?
10. Page 13, line 279: Replace “that are also” with “that also”
11. Page 14, lines 283-289: I do not agree. Nesting beaches that have evolved and stabilised despite a costal mortality bottleneck related to the higher predation of hatchlings during the first swimming phase, rely on a higher offspring production and therefore efforts to reduce terrestrial predation or any other threats at the nesting beaches will be relevant.
12. Page 14, line 284: Transport distances are shown in Fig. 2 (in Fig.4 is standard deviation of Transport distance), please add this reference
13. Page 14, line 290: Add reference to Fig 2B
14. I suggest you present also the figures on the standard deviation of transport distance for the different time steps.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Sirs,

I found your manuscript appropriately structured and particularly stimulating in the very important attempt to compare marine and terrestrial scenarios.

Sea turtles, more than "meroplanktonic species", have a migratory behavior in a bi-dimensional space (like terrestrial species and differently from many marine fishes), in addition to the passive dispersal of early stages (like more meroplanktonic invertebrate species). The paper offers an evident element for understanding this last aspect (passive dispersal), but it extends the interpretation to hundreds kilometres (... this is another link to the terrestrial approach: why not Nautical Miles?), hence also to life stages not properly passive. The manuscript deals with the only marine currents, and this is OK, but I would like that Authors indicate somewhere in the text that such a kind of data have to consider (as for cited predation, anthropization disturbance, and so on) also the swimming behavior of species in the understanding of their dispersal range.

apart this punctuate suggestion, I would like to stimulate a more appropriated use of scientific terminology, which should be a good thing in a scientific article. I indicated directly in the text where this has been considered as necessary.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf