Acoustic Complexity and Biodiversity in Boca Ciega Bay, FL

Passive acoustic monitoring (PAM) is an emergent method with potential in noninvasive assessment of fragile habitat and organisms such as seagrass beds and estuarine fish.

Data analysis for PAM has historically been difficult and time consuming, however, acoustic complexity indexes (ACI) streamline this process. ACI are useful tools for measuring biodiversity of vocalizing organisms. The application of ACI to estimate biodiversity is broad, previously displaying a positive correlation with richness.

Audio sampling was conducted using a hydrophone with a piezoelectric pickup deployed at a typical water depth of 1m for a 10 minute period. Audio clips were divided into 10 second clips for ACI determination of frequencies 50-2000 Hz, within which range fall all documented fish vocalizations we are aware of. Immediately after audio sampling, fish biodiversity was sampled by pulling a seine net through a set square area along the Eckerd College seawall weekly at 13:00 and 22:00 between summer and winter 2025. Results indicate a strong positive correlation between median ACI and biodiversity as measured by the Shannon Index, a moderate negative correlation between abundance and maximum ACI, and a significant positive correlation between median ACI and species richness. This is interesting since, to our knowledge, there has not previously been research linking acoustic data with biodiversity within Tampa Bay. Coastal estuarine ecosystems are especially vulnerable to climate change impacts, thus it is imperative to establish baselines of biodiversity and abundance.