The PIs will conduct two bodies of field work detailed below.

1) Characterization of dynamic beach features, wrack, and vegetation to investigate ecosystem dynamics and
recovery of features including climbing dunes and vegetation before (summer 2026) and following (Winter
2027, Summer 2027, and Winter 2028) a strong El Niño event and to continue long-term time series on
Percos, North, and Cojo Beaches. PIs will continue to utilize new approaches to quantify the elevations and
extent of beach features and the dynamics and distribution of wrack subsidies to the beaches as well as
coastal strand and dune vegetation using drone and ground-based transect surveys. The unique combination
of intense physical dynamics and processes and high subsidies found on the Dangermond Preserve beaches
make these beaches an ideal study site for this research which can be expanded along the undeveloped
Gaviota coastline.

• PIs will use a multispectral drone in conjunction with transect surveys to collect additional data and
  calibrate and ground truth these methods and observations at Percos, North, and Cojo beaches,
  providing needed data from pristine, wild mainland beaches. They will also incorporate these data into
  models being developed to automatically detect and quantify wrack and dune vegetation cover. In
  addition, they will use the resulting data to train a different model for the identification of coastal strand
  and dune plant species. These surveys will produce orthomosaics of the site which can be used in
  additional spatial analyses.
• PIs will also use a mobile, RTK-enabled GPS unit paired with Starlink Wifi to collect ground control
  point position and elevation data on dynamic beach features and elevations. Using the elevation data
  from the drone and this GPS unit they will construct site-wide digital elevation models (DEMs) for
  each survey. The high-resolution elevation data will be available to refine predictions and modelling
  for projecting the effects of sea level rise and storm impacts on biodiverse Dangermond Preserve
  beaches.
• To ground truth the drone surveys, PIs will conduct transect-based surveys of dune vegetation cover,
  wrack cover, and physical features of the beaches and dunes (dune crest, dune toe, vegetation toe, high
  tide strandline, berms, water table outcrop, etc.). They will also collect RTK GPS data on the position
  and elevation of these features.

2. Surfperch diet and food web connections: PIs have completed the analysis for the study of barred surfperch
diet. PIs will complete and submit a manuscript for publication comparing fish diet in an MPA (Percos) and
at a reference beach (Refugio) and also identifying patterns in resource use based on fish maturity (size).

3. Talitrid amphipod population surveys: Talitrid amphipods are sensitive indicators of injury from oil spills
and other impacts, including El Niño-driven storm disturbance. The PIs will continue semi-annual surveys
of talitrid amphipods at Percos, North, and Cojo Beaches to extend the time series on these indicator taxa
that can be used to track condition of the beach ecosystem.