Sapelo Research Application Form
Research Application ID: GCE-123-2022 (submitted: 05/23/2022, status: approved)
Provide a brief title for web display
Assessing mechanisms of mesopredator release in southeastern US salt marshes
Investigator Information
On Island Sponsor: GCE SINERR UGAMI GADNR
| Principal Investigator: | Brian R. Silliman | ||
| Home Institution: | Duke University | ||
| Award Information: | GCE-LTER supplemental covid funding | ||
| Mailing Address: | 135 Duke Marine Lab Rd. | Phone Number: | (352) 392-1137 |
| Duke University Marine Lab | E-mail Address: | brian.silliman@duke.edu | |
| Beaufort, North Carolina 28516-9721 | |||
| Co-investigators: | Ryan Rogers (Duke University) | ||
Briefly describe the project goals and methodology
In southeastern US salt marshes, grazers can powerfully control plant ecosystem diversity, biomass, and plant-geomorphological interactions. While these grazers are heavily preyed on by nektonic predators, it is uncertain whether the loss of these predators will lead to increased grazer densities or whether mesopredators, that are also eaten by these swimming predators, will increase. To test this, in 2017 we set up large (25m2) nektonic predator exclusions in marshes at the GCE LTER to test whether southern US salt marsh ecosystem showed that the exclusion of large predators (blue crabs, diamondback terrapins, red drum, and American alligators) resulted in an initial increase in the abundance of grazing marsh periwinkle snails (Littorina irrorata) and grazing pressure on marsh plants. However, this initial increase in grazing snails was followed by an increase in mesopredatory mud crabs and subsequent decline in grazer densities to control levels. While these observations suggest mesopredators compensate for nektonic predator loss and thus increase marsh resilience to food web disturbance, they have not been tested experimentally. Here we propose a one year-long study, beginning in summer 2022, to test the relative impacts of mesopredators and large nektonic predators on population growth of the dominant marsh grazers. In this study, we will manipulate mesopredatory crab presence within 50 × 50 cm cages established in the intermediate Spartina zone of a salt marsh within the GCE LTER.
Where will the project be located?
Lighthouse Marsh, low-intermediate spartina zone
How will you provide GPS coordinates for study sites?
I will provide a spreadsheet containing GPS coordinates for my study sites
What are the expected start and end dates of the project?
Start Date: 06/30/2022 End Date: (ongoing)
How many people will access the site and at what frequency?
3 people, 8 days every month through August
Keywords that describe your project
What equipment will be deployed in the field?
Exclusion cages, composed of wooden stakes, andvexar mesh netting, (30) 50 x 50 cm cages, across three treatments. Equipment will be deployed entirety of spartina growing season, mid-late june - mid to late august/october.
Will plants or animals be collected as part of this study?
Collection and removal of panopeus in experimental plots, assessment of biomass and population structure.
What are the likely impacts of the project on the site?
Placement of (30) cages along the intermediate spartina zone, potential for trampling/disruption of spartina plants.
Will the project design include boardwalks? If not, explain why not.
No, planned to make uise of low-tide and marsh waders to access field sites and collect data
How long will impacts persist after the research is concluded?
Changes in vegetative presence as a result of this experiment may persist through the next growing season of Spartina, roughly one year.
Research Permits:
Georgia DNR Coastal Resources Division: GCE-123-2022_Permit_RLS20220028_SillimanRogers_Mesopredators_signed (06/22/2022-08/25/2023)
Files attached to this application
GCE-123-2022_Photos_Cage_Prototype.pdf (PDF file, 3176.66 kb, submitted 07/27/2022)
