Grant: 23-002R
Project Title: Using Passive Acoustic Monitoring to Determine Exposure Levels of Marine Turtles to Vessels in North-Western, Florida
Project Manager: Mariana Fuentes and Julia Saltzman
Organization: Florida State University (Research and Educational Institute)
Grant Amount: $21,644.65
Completion Date: 2025-09-24
Summary: As a group which often inhabits shallow coastal waters, marine turtles often occur in waters with high frequency of boating activity. Vessel presence and traffic can affect the fitness of individual turtles, impact their energy expenditure, cause changes in foraging activities, and displacement. To fully quantify the exposure of marine turtles to vessels, long term, comprehensive, and continuous assessment is needed, where temporal, seasonal and daily exposure levels can be determined. This much-needed, continuous assessment can be obtained through Passive Acoustic Monitoring (PAM). The aim of this project is to use soundscape to quantify duration and quantity of vessel traffic and boat noise within important marine turtle habitats. Through PAM, we will be able to examine spatial and temporal variation of boat traffic and vessel noise and determine variability during and outside the scallop season. By identifying and characterizing patterns in boat traffic, we will determine which areas within an important foraging area have the greatest potential for turtle-boat interactions (i.e., areas with high levels of boat traffic may have the greatest potential for vessel strike). In this project, we will deploy acoustic recording instruments at areas previously identified to have high density of marine turtles in the Crystal River within the Big Ben Region of Florida. Studying the Big Bend is of particular interest, since it supports the state's largest recreational bay scallop harvest and serves as important habitat for three species of marine turtle: green, Kemp's ridley, and loggerhead turtles. If funded, this project will provide a comprehensive assessment of marine turtle exposure to vessels in Crystal River. Within this, we can identify what factors increase vessel traffic and presence, and thus what factors may lead to increased frequency of vessel strikes.
Results: Because of the delays, and the arrival of our instruments in late-July and August 2023 (after our team left for August fieldwork and after the start of the scallop season), thus we were unable to conduct the research as intended and decided to postpone the full sampling to 2024, while collecting baseline data in 2023. Having said this we collected baseline data to inform the full deployments in 2024, which included the deployment of Hydromoths in two locations in July, August, and September, and an ST600 deployment in September. In August 2023, we deployed Hydromoths at 2 locations. The ST600 instruments arrived in time for our September 2023 trip. In September 2023, we deployed 1 ST600 and 2 Hydromoths. Our full deployment of all equipment started in February 2024 and all the equipment was retrieved in October 2024. Analysis included: Long Term Spectral Average (LTSA) plots, one per site including the total available deployment times; Diel variation plots, one per site including the total available deployment times; and Plot containing daily median 5th, 50th, and 95th percentile ambient sound levels (dBRMS 100-900 Hz) for all three locations and full deployment times.