Using before-after control-impact methodology to quantify effects of full ship shock trial explosions on marine fauna

In the summer of 2021, the US Navy conducted a Full Ship Shock Trial (FSST) for the USS Gerald R. Ford. This involved three large underwater explosions off the coast of Florida, USA. We collected underwater acoustic recordings, using low-sensitivity recorders, for the Naval Undersea Warfare Center to validate their underwater acoustic propagation models. We also deployed SoundTraps on the shallow moorings to collect additional acoustical biologics data in hopes of measuring any acoustic responses of marine fauna to the explosions. The acoustic energy of the explosions did not propagate up the continental slope and were hence not captured by the SoundTraps on the shallow moorings. However, our analyses did yield some notable changes in acoustic behavior after as compared to before the explosions. Here, we describe how our field plan was designed for before-after control-impact (BACI) hypothesis testing and discuss our analyses and findings of the few significant cases. These results lend insight for improving the impact assessments and conducting behavioral response studies during a future FSST or other large underwater explosions.