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Home My WebLink About20231056 Ver 1_More Info Received_20231023 October 23, 2023 Hello, Please find below the responses in italics to questions raised about the CAMA permit application for the DRAGNet marsh experiment. Please reach out if clarification is needed or additional questions arise. Sincerely, Stephanie Valdez PhD Candidate Nicholas School of the Environment Duke University 1. In the email received by DWR on August 12 you listed clarifications on what NPK fertilizer will be used, can you please clarify what will the application method be and will the additional nutrient be granular or spray sticky substance Fertilizer will be added in granular form, not spray. 2. Please clarify if the applied nutrients infiltrate into the substrate within a certain period of time or within a 12-hour tidal cycle. We will be using a time-release N formula and therefore it will not be released within a 12-hour tide cycle. However, the application of the nutrients will occur by mixing nutrients into the first several cm of sediment to ensure it is not washed away. 3. Please clarify how the application rate of 10 g m¯² was determined. This is the amount set by the DRAGNet procedure that all sites in the network adhere to. This ensures experimental uniformity across the global experiment. 4. Please provide details about how you intend to contain fertilizer within the project boundaries from the surrounding surface waters in a tidal system. Because of the flooding in marshes, we will be “scratching” the nutrients into the sediment. In other words, we will be digging small holes/ channels to mix the nutrients with the sediment several centimeters down so that it is not washed away with a single tidal cycle and stays within the experimental plots. 5. DWR requests a monitoring plan be developed sampling for TKN, Total Phosphors, pH, dissolved oxygen (DO) and Chlorophyll A around the project area to see how the additional nutrients impact the water quality in the area. We will collect triplicate 0.5l water samples from the nearest shore adjacent to the experiment (south side of the experiment) and test for TKN, Total Phosphors, pH, dissolved oxygen (DO) and Chlorophyll A. We will collect these samples annually when we visit the site for monitoring. 6. Please provide what soil parameters you will be analyzing for, what lab you are using, and the detection limits. Soil will be analyzed for NPK by the University of Minnesota. 7. Please provide more detail about what the tilling of the marsh mimics or represents. Tilling represents a major disturbance to the area and creates a blank space for re-colonization to occur. The experiment explores how grasslands respond to a mix of disturbance and nutrient availability change across a global scale. The total disturbance of an area allows for uniform methods across grassland types and therefore, allows the results to be compared across the globe. 8. Please provide any examples of similar project that have been conducted in coastal wetland environments. This is a global project with over 75 sites across 6 continents following the same methods. Within our region, there is a site set up in the Duke Forest in Durham, and another site in a Georgia salt marsh on Sapelo Island. Beyond this project, mimicking disturbance and nutrient availability have been cornerstones in marsh ecology for decades. Below is a brief list of published experiments that have used nutrient enrichment, disturbance, or both in coastal wetlands to answer various questions. Brown, J. K., & Zinnert, J. C. (2021). Trait-Based Investigation Reveals Patterns of Community Response to Nutrient Enrichment in Coastal Mesic Grassland. Diversity, 13(1), Article 1. https://doi.org/10.3390/d13010019 Carvalho, P., Thomaz, S. M., Kobayashi, J. T., & Bini, L. M. (2013). Species richness increases the resilience of wetland plant communities in a tropical floodplain. Austral Ecology, 38(5), 592– 598. https://doi.org/10.1111/aec.12003 Hensel, M. J. S., Silliman, B. R., Hensel, E., & Byrnes, J. E. K. (2022). Feral hogs control brackish marsh plant communities over time. Ecology, 103(2), e03572. https://doi.org/10.1002/ecy.3572 Pennings, S. C., Stanton, L. E., & Stephen Brewer, J. (2002). Nutrient effects on the composition of salt marsh plant communities along the Southern Atlantic and gulf coasts of the United States. Estuaries, 25(6), 1164–1173. https://doi.org/10.1007/BF02692213 Silliman, B. R., He, Q., Angelini, C., Smith, C. S., Kirwan, M. L., Daleo, P., Renzi, J. J., Butler, J., Osborne, T. Z., Nifong, J. C., & Van De Koppel, J. (2019). Field Experiments and Meta-analysis Reveal Wetland Vegetation as a Crucial Element in the Coastal Protection Paradigm. Current Biology, 29(11), 1800-1806.e3. https://doi.org/10.1016/j.cub.2019.05.017 Silliman, B. R., & Zieman, J. C. (2001). Top-down Control of Spartina Alterniflora Production by Periwinkle Grazing in a Virginia Salt Marsh. Ecology, 82(10), 2830–2845. https://doi.org/10.1890/0012-9658(2001)082[2830:TDCOSA]2.0.CO;2 Touzard, B., Amiaud, B., Langlois, E., Lemauviel, S., & Clément, B. (2002). The relationships between soil seed bank, aboveground vegetation and disturbances in an eutrophic alluvial wetland of Western France. Flora - Morphology, Distribution, Functional Ecology of Plants, 197(3), 175–185. https://doi.org/10.1078/0367-2530-00029 Wang, C., & Li, B. (2016). Salinity and disturbance mediate direct and indirect plant–plant interactions in an assembled marsh community. Oecologia, 182(1), 139–152. https://doi.org/10.1007/s00442-016-3650-1 9. Please provide a plan for the revegetation or remediation if the project is not successful or if unintentional or additional impacts occur to the surrounding coastal wetlands outside of the project area. If there remains unvegetated space at the end of the project, we will plant S. alterniflora. S. alterniflora is available from local nurseries and readily used in restoration projects in the area. Using clumped planting methods, we will plant a minimum of 10 plants/m2. In this arrangement, S. alterniflora has been shown to rapidly expand and regrow in bare spaces. In addition, as part of the agreement to work on the Rachel Carson, we have agreed to restore the area to previous conditions if, revegetation does not occur over the course over the 10 year experiment.