Environmental indicators from underwater soundscapes and simultaneously collected non-acoustic data

Abstract

Drawing environmental conclusions from underwater acoustic recordings alone can to be challenging as most received sounds, especially in shallow water, are from sources that cannot easily be classified. This presentation will discuss two ongoing projects in which soundscapes were recorded simultaneously with non-acoustic, validating environmental data. In one case, acoustic data were collected simultaneously with bottom composition, organism censuses, and night-time time-lapse imagery over shallow reefs in the Hawaiian Islands. Multivariate analysis showed that areas defined by a “cool tropics” oceanographic regime grouped along a principal component parallel to monotonically increasing acoustic frequency: protected or more remote sites produced soundscapes that featured greater levels of low frequency (<2 kHz) biological sound. Degraded and/or algae dominated sites produced soundscapes featuring higher levels of high frequency (2-20 kHz) sound. The second case involves experimental work using hyperspectral optical data and simultaneously obtained acoustic recordings in shallow water, combined with in-situ spectrophotometer readings and visual benthic surveys. Optical reflectance and sound are produced through completely different mechanisms, yet the underlying environmental phenomena we wish to evaluate exhibit both. This presentation will discuss the potential of fusing these data in order to enhance our understanding of the shallow water environment. [Work supported by ONR.]