June 2025

Oceanography | Vol. 38, No. 2

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(https://www.ncei.noaa.gov/products/passive-acoustic-data),

and all processed data products are accessible through the

ADEON Data Portal (https://adeon.unh.edu/data_portal).

SIGNIFICANT CONTRIBUTIONS

The overarching goal of ADEON was to establish an integrated,

deep-water acoustical observing system for the US Mid- and

South Atlantic OCS that generated year-round measurements of

the natural and human factors driving the regional ecology and

soundscape over several years and that are transferable to other

locations. To meet this goal, the program generated new tech­

nology, infrastructure, measurement, and analysis approaches

that have since been applied to other regions. The ADEON effort

went beyond data collection and analyses related to monitor­

ing ecosystem components to perform basic science and pub­

licly disseminate the data to support future research. Science

and innovation accomplishments of ADEON include (1) devel­

opment and implementation of standardized acoustic metrics

and practices across ADEON components that are serving as

a model for national and international soundscape programs,

(2) development of an Autonomous Long-Term Observation

(ALTO) lander that simultaneously records acoustic (passive

and active) and oceanographic information, (3) identification

of the horizontal range of extrapolation for acoustic backscat­

ter point samples recorded at each lander location for guiding

future monitoring designs (Blair et al., 2021), (4) documenta­

tion of minke whale winter mating grounds in the southern

and offshore waters of the Blake Plateau (Kowarski et al., 2022),

(5) determination of site fidelity of beaked whale species along

the southeastern US OCS (Kowarski et al., 2022), (6) model-data

comparison of combined wind and vessel soundscape model

levels (Heaney et al., 2024), (7) modeling of regional ecology to

predict potential influences of long-term change on marine eco­

systems, and (8) development of web-based tools to access and

visualize multi-dimensional data streams.

The ADEON team established a long-term (three-year)

observing network that provided the first publicly avail­

able, multi-​location (seven sites), wide-band (10–7,000 Hz),

FIGURE 1. (a) Data was collected for the Atlantic Deepwater Ecosystem Observatory Network (ADEON) using fixed and mobile platforms, shipboard

sampling, and satellite remote sensing. (b) Schematic of the Autonomous Long-Term Observatory (ALTO) landers used in ADEON. Hydrophones were

spaced between 0.45 m and 0.68 m. (c) ADEON sites overlayed with bathymetry. Standard landers had a passive acoustic system and oceanographic

sensors. The Standard with the Acoustic Zooplankton Fish Profiler (AZFP, ASL Environmental Sciences, Canada) landers had the addition of an echo

sounder system. (d) ADEON sites ordered from north to south.