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Wiggins, SM, Leifer I, Linke P, Hildebrand JA.  2015.  Long-term acoustic monitoring at North Sea well site 22/4b. Marine and Petroleum Geology. 68, Part B:776-788.   10.1016/j.marpetgeo.2015.02.011   AbstractWebsite

Marine seeps produce underwater sounds as a result of bubble formation and fragmentation upon emission from the seabed. The frequency content and sound levels of these emissions are related to bubble size distribution and emission flux, providing important information on methane release from the seafloor. Long-term passive acoustic monitoring was used to continuously record seep sounds over a 7-month period within the blowout crater at the abandoned well site, 22/4b, in the central North Sea. Also recorded were water column fluid velocities and near-seafloor water conductivity, temperature, and pressure. Acoustic signatures were primarily from ∼1 to 10 kHz. Key features were relatively broad spectral peaks at about 1.0, 1.5, 2.2, 3.1, 3.6 and 5.1 kHz. Temporal variations in spectral levels were apparently associated with tides. The recordings also documented a series of major episodic events including a large and persistent increase (∼10 dB) in overall sound levels and spectral broadening on 8 December 2011. The acoustic temporal pattern of this event was consistent with other recorded large transient events in the literature, and the major event was correlated with dramatic changes in other measurements, including increased water column fluid velocities, increased pressure and decreased salinity, indicating real changes in emission flux. Observed seabed morphology changes reported elsewhere in this special issue, also likely were related to this event. These data demonstrate the dynamic nature of marine seepage systems, show the value of monitoring systems, and provide direct supporting evidence for a violent formation mechanism of many widespread seep-associated seabed features like pockmarks.

Wiggins, SM, Hildebrand JA.  2016.  Long-Term Monitoring of Cetaceans Using Autonomous Acoustic Recording Packages. Listening in the Ocean. ( Au WWL, Lammers MO, Eds.).:35-59.: Springer New York   10.1007/978-1-4939-3176-7_3   Abstract

Autonomous acoustic recorders have advanced our understanding of cetaceans, providing information for better models of species distribution, behavior, ecology, and conservation. For over a decade, Acoustic Recording Packages (ARPs), and its broader-bandwidth successor, High-frequency Acoustic Recording Package (HARP), have been used for Passive Acoustic Monitoring (PAM) providing high-fidelity, long-term acoustic data sets for cetacean studies. Some of these studies are summarized below showing a wide range of applications and results including species signal characterization, seasonal and daily presence patterns, geographic and habitat use, population density and abundance estimations, acoustic stimuli behavioral response, and swimming behavior via array tracking. Species studied include low-frequency baleen whales and high-frequency dolphins and beaked whales.