PASSIVE ACOUSTIC MONITORING
Noise mapping
In 2007, collaborators from the Stellwagen Bank National Marine Sanctuary (SBNMS), the Northeast Fisheries Science Center, Cornell Laboratory of Ornithology's Bioacoustics Research Program (BRP) and Marine Acoustics, Inc. (a private company based in Rhode Island) began a three-year project continuing efforts to characterize the underwater acoustic environment of the sanctuary and further examining the effects of noise on resident marine animals.
Since December 2007, arrays of marine autonomous recording units (MARUs) have been deployed in the sanctuary to record low-frequency underwater sound (10 to 1000 Hz). MARUs arrays will be used to gather acoustic data in the sanctuary over a continuous 30 month period. During the same time period, collaboration with the US Coast Guard's Research and Development Center and the University of New Hampshire’s Center for Coastal and Ocean Mapping is enabling the SBNMS to continuously track all large vessel traffic in greater sanctuary waters using the US Coast Guard’s Automated Identification System (AIS). Acoustic data are then combined with AIS data to build upon previous efforts to assess the relative contributions of different types of vessels and other sound sources to the total "noise budget" of the sanctuary.
Long-term spectrogram and received levels over time for select 1/3rd octave frequency bandwidths from a single MARU location in the SBNMS acoustic array on December 27 2007. Note peaks in received levels associated with a transiting commercial vessel and vocalizing whales and fish.
MARUs are also being used to detect, locate and track vocalizing marine mammals such as North Atlantic right whales, humpback whales, fin whales and fish species such as cod and haddock. These analyses rely heavily on software developed by and available through BRP.
Call detection rates for three species at a single MARU location in the SBNMS acoustic array on December 27 2007. Note that all species show elevated calling rates toward the middle and end of the day.
Information regarding the distribution of anthropogenic and natural sources of underwater noise (including vocally-active whales and fish) and information from ongoing whale tagging efforts are being used to better understand whether and how animals change their behaviors in noisy environments. These integrative analyses rely heavily on accurate modeling of sound propagation throughout sanctuary waters, which varies among source types, as well as with depth, bottom type, water pressure, water temperature and water salinity (among other factors). Data from the AIS, MARUs, tags on whales, and environmental sensors are used to predict variation in the SBNMS’s “soundscape” using the Acoustic Integration Model© (AIM©, software developed by Marine Acoustics, Inc.). Additional analytical tools created by BRP in Matlab (Mathworks, Inc.) are used to manipulate and display AIM©output over various temporal and spatial scales. This methodological approach is then used to predict the areas over which a marine animal can transmit or receive acoustic signals and estimate the relative changes in these areas as a result of changes in the animal’s acoustic environment.
Four panels showing the received level gridded surfaces predicted by AIM© to represent contributions to the 100Hz 1/3rd octave frequency bandwidth between 05:40 and 05:50 on 27 December 2007 by A) wind, B) large commercial vessels, C) up-calling right whales and D) a summation of A-C. Received level intensities (dB re 1µPa) are scaled according to the legend on the right.
This project represents a high-level, integrative ‘bench mark’ study aimed at characterizing the marine acoustic environment and the health of an urbanized, highly productive ecosystem: the SBNMS. The primary products of the project will be a suite of tools intentionally designed to be transferable to other ecological regions or sanctuaries and an extensive database specific to the project. The project’s database is built and managed to promote interfacing with other oceanographic datasets (including OBIS SEAMAP, and the Whale Habitat Informatics Project (WHIP)) and methods to display results are developed to be useful and accessible in a variety of education and outreach contexts.
This research is funded by an award from the National Oceanographic Partnership Program.
For more information on this project see
http://streams.wgbh.org/
http://www.nefsc.noaa.gov/
http://www.birds.cornell.edu/brp/
Going Green Boston, WCVBTV/DT Channel 5 Boston, "Noise Pollution Hurting Marine Wildlife: Noise Can Interfere With Animals' Communication", original air date September 9 2008.
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