Passive acoustic monitoring of hydrothermal vents at the endeavour hydrothermal vent field

Abstract

Passive acoustics may provide a method for detection and long-term monitoring of hydrothermal vents. Direct measurement of vent activity can be challenging as vent plumes are often high temperature (i>300°C) and acidic. The discovery of new vent sites can also be challenging as detection of vent plumes or high-resolution seafloor mapping is required. For these reasons, remote detection and monitoring with passive acoustics can be advantageous. In this presentation, long-term passive acoustic data recorded in 2019 from an Ocean Networks Canada (ONC) bottom-mounted hydrophone in the Endeavour Hydrothermal Vent field are presented. A 6-month time window from April through October 2019 was selected for analysis, when fin whale calls were less prevalent. Statistical noise level metrics (e.g., the median) were used to reduce the influence of transient, infrequent events such as fin whale calls and ship noise, as the vent signal was expected to be relatively constant compared to these sources. Spectral analysis of the resulting time series across multiple frequency bins shows evidence of tidal-period variations in power spectral density which may be related to hydrothermal vent dynamics. Comparison is made to other nearby ONC sensors such as vent temperature, bottom pressure, and acoustic doppler current profiler measurements.