Exposure of Loggerhead Sea Turtle Nests to Waves in the Florida Panhandle

Round 1

Reviewer 1 Report

Reviewer (Remarks to the Authors):

Submission: RS-2021-1231779-Exposure of loggerhead sea turtle nests to waves in the Florida Panhandle

 The manuscript tackles an important question“the potential effect of wash-over on loggerhead sea turtle productivityusing a geographic information system coupled with remote sensing and wave runup modeling”. Given the topicality of this area I believe that this manuscript could have an impact as a scientific report addressed to the scientific community, managers and police markers, etc, taking onto account the potential global climate change and consequently, the potential increasing storm frequency events. The manuscript is well written, and I enjoyed reading it. The methods are quite detailed, which allows it to be easily replicated and the discussion highlights the importance of prior assessments for efficient management measures.

I have included the suggestions in the doc to facilitate the minor revision.

At this point, I only have some comments to help reforce the version. Taking all these matters into consideration, my recommendation is to 'resubmit the paper with the minor suggestions addressed and be accepted”.

I wish them the best of luck in these efforts.

 

 

 

 

Comments for author File: Comments.pdf

Author Response

We appreciate the Reviewers contributions and have provided a point-by-point response below. Any revisions can be found in the Track Changes document submitted to the Editor.

• The suggested citation was added to Line 44.
• Nest productivity assessments were clarified in Line 119 as hatching and emergence success. The calculation of these is provided in Lines 141-142. Citations to these calculation have been added to Line 143. The reference to post-hatchling emergence assessment was removed for clarity.
• Predation was included in the Results to provide context for the reader regarding the severity of the threat of wave exposure, as predation is another common significant threat experienced at sea turtle nesting beaches. Lines 287-289 were retained to continue to provide this context.
• In Lines 309-310, “berm crest” was defined as the shore-parallel ridge where the sloped beach face transitions to the flat berm above the swash zone. Berms are the flat portion of the beach where most sea turtle species nest; therefore, their impact on nesting was not further described. The presence of cliffing at the beach face or other erosional features may affect sea turtle nesting, but that is beyond the scope of this manuscript.
• Additional references regarding the hatching success effects of protracted rainfall were added to Line 357. Rainfall was not specifically recorded as part of this study but could be investigated in future efforts due to the wide availability of rainfall data throughout the study region.
• Line 399 (Line 402 in the revised version) was reworded to clarify the subsequent questions represent knowledge gaps which currently hinder our management efforts.

Reviewer 2 Report

The research work entitled Exposure of loggerhead sea turtle nests to waves in the Florida 2 Panhandle, is an interesting manuscript that describes a novel method to model wave dynamics in a specific coastal region.

Although in some sections of the text it could be excessively complex, the amount of detail provided is appreciated.

The methodology is very detailed and it will surely have a great scientific diffusion as another application of satellite images for the conservation of nature.

Regarding the Methods, at what scale is the resulting DEM, has it been necessary to downscaling with respect to the resolution of the chosen satellite images?

Have other types of meteorological data been taken into account, such as the wind regime, or the trend in the frequency of coastal storm events? These data would add a new dimension to multivariate analysis.

In line 201. What does the subindex "2" of R mean, is the same R as in the formula on line 222? Please explain it.

In Results section. How have NA beaches been treated? Have they been evaluated in the same way as the rest for the calculation of the final priority?

Has the percentage accuracy of the FWC observations been measured? And in the case of measuring it, how has it been done?

Please explain the Priority Category finally granted which seems to be the sum of Nest Frequency and Wave Exposure Categories.

Author Response

We appreciate the Reviewers contributions and have provided a point-by-point response below. Any revisions can be found in the Track Changes document submitted to the Editor.

• The DEM was created with a 3-m pixel size. Though this is a high-resolution, large data file to work with at this regional scale (and downscaling would have certainly improved the processing requirements), the benefits for each local nesting beach to have access to high-resolution maps of their individual piece of the region outweighed the computational costs.
• As the prevailing wind regime would influence wave characteristics, it is implicitly included in the wave modeling assessment via the resulting observed wave height and period. Shifts in wind speed or direction would alter the observed hourly or daily wave data that drove our model. As for the frequency of coastal storm events, observations taken during these events which fell within the study area and timeframe were included. Moving forward, modeling exercises could be pursued which investigate the change in exposure associated with more frequent or strong storm events, but this was outside the scope of the present manuscript.
• R₂ in both equations denotes the 2% exceedance limit for wave runup as defined in Stockdon et al. (2006, Citation 54 in the manuscript). This 2% cushion was included 1) so as not to model the most extreme single wave observation (which is highly prone to error), and 2) because it is common practice in coastal engineering applications.
• Wave runup elevations were modeled at NA beaches as beach elevation, tide, and offshore wave information was available for these locations. However, since no nesting data was available, they were excluded from the prioritization assessment. If nesting data were to become available, the proportion of nesting exposed and their subsequent prioritization could be evaluated.
• We are assuming by “percentage accuracy of the FWC observations”, you are referring to the hatching and emergence success values? Ceriani et al. (2021, Citation 59 in the manuscript) recently published an assessment of factors related to biases in success evaluations and found that errors for loggerhead and green turtle nests (i.e., the most common nesters in Florida) were exceedingly low – though factors like total clutch size, incubation duration, species may affect accuracy.
• The final Priority Category was calculated as the product of nesting frequency and the proportion of exposed nests and subsequently converted into quantiles. This is included in Lines 258-267 (Lines 259-268 in the revised manuscript).

Reviewer 3 Report

I am delighted to read through this work and feel that it is a welcome and much needed tool in resource management. The higher level assessment of nesting beach exposure to wave action offers a novel process to consider in the determination of priority beaches aside from nesting numbers alone. As sea turtles continue to face new challenges worldwide, decisions will need to be made regarding what methods of intervention are truly most effective and necessary, and where best to focus conservation resources for their continued recovery.

Comments for author File: Comments.pdf

Author Response

We appreciate the Reviewers contributions and have provided a point-by-point response below. Any revisions can be found in the Track Changes document submitted to the Editor.

• Comparisons to previous studies are provided in the Discussion in Lines 355-357 (Lines 357-359 in revised manuscript). In general, these rates of exposure appear typical of the peer-reviewed literature available.
• The DEM which underlies the modeling efforts has a 3m pixel size. The 5m accuracy of the handheld GPS units may result in a shift of 1 pixel relative to the nest’s true location, which is unlikely to significantly alter it’s modeled exposure risk.
• The removal of sand during erosive events (such as storms) would expose the eggs. The typical summer regime in the study region is depositional, adding sand or wrack material on top of the nest surface during wave exposure. However, as both the removal or deposition of sand or wrack can indicate a wave wash-over event, they were listed together in the manuscript.
• It is unclear what the Reviewer is referring to for additional definition. Can you be more specific? As for documented inundation, the provided definition in Lines 136-137 is the criteria provided by the Florida Fish and Wildlife Conservation Commission for uniform reporting across the state. There are ongoing efforts to monitor nest inundation during incubation, rather than just at nest excavation, to better describe its effects on hatchling production (i.e., addressing Questions 1-3 presented in the Discussion).
• Beach variability is presented in Appendix C for additional reader investigation.
• As the prevailing wind regime would influence wave characteristics, it is implicitly included in the wave modeling assessment via the resulting observed wave height and period. Shifts in wind speed or direction would alter the observed hourly or daily wave data that drove our model. Storm surge is included in tide height reported at tidal stations.
• One objective of this work is to help identify beaches where wave exposure may have the largest population-level impact. When standardizing by nesting density, there were smaller beaches like Deer Lake State Park which ranked very highly - despite only having a handful of nests, their small size meant they had a high nest density. If any management efforts were targeted at these beaches, they would only affect a small number of nests which contribute relatively few hatchlings to the population at-large. By using the non-standardized nesting frequency (# nests per year) in the rankings, beaches with more nesting score higher because even if a lower proportion of the nesting at those larger beaches are exposed, the number of exposed nests likely outweighs the total nesting at the smaller beaches. Addressing wave exposure at these beaches would have a larger impact on the population as a whole.
• Observations taken during storm events which fell within the study area and timeframe were included. However, their frequency of occurrence is very low compared to typical daily sea conditions. This extreme tail of the distribution would increase the modeled average wave exposure per pixel in DEM to a small extent. In addition, as storm events are the primary driver of nest loss due to wave exposure in this study area, including their observation is critical to the potential future management applications of this manuscript.
• Several studies which describe nest loss at various sites are presented in Lines 355-357 (Lines 357-359 in revised manuscript).