Understanding relationships between physical drivers and biological response is central to advancing ecological knowledge. Wind is the physical forcing mechanism in coastal upwelling systems, however ...lags between wind input and biological responses are seldom quantified for marine predators. Lags were examined between wind at an upwelling source, decreased temperatures along the upwelling plume's trajectory, and blue whale occurrence in New Zealand's South Taranaki Bight region (STB). Wind speed and sea surface temperature (SST) were extracted for austral spring-summer months between 2009 and 2019. A hydrophone recorded blue whale vocalizations October 2016-March 2017. Timeseries cross-correlation analyses were conducted between wind speed, SST at different locations along the upwelling plume, and blue whale downswept vocalizations (D calls). Results document increasing lag times (0-2 weeks) between wind speed and SST consistent with the spatial progression of upwelling, culminating with increased D call density at the distal end of the plume three weeks after increased wind speeds at the upwelling source. Lag between wind events and blue whale aggregations (n = 34 aggregations 2013-2019) was 2.09 ± 0.43 weeks. Variation in lag was significantly related to the amount of wind over the preceding 30 days, which likely influences stratification. This study enhances knowledge of physical-biological coupling in upwelling ecosystems and enables improved forecasting of species distribution patterns for dynamic management.
The effects of chronic exposure to increasing levels of human-induced underwater noise on marine animal populations reliant on sound for communication are poorly understood. We sought to further ...develop methods of quantifying the effects of communication masking associated with human-induced sound on contact-calling North Atlantic right whales (Eubalaena glacialis) in an ecologically relevant area (∼10,000 km 2 ) and time period (peak feeding time). We used an array of temporary, bottom-mounted, autonomous acoustic recorders in the Stellwagen Bank National Marine Sanctuary to monitor ambient noise levels, measure levels of sound associated with vessels, and detect and locate calling whales. We related wind speed, as recorded by regional oceanographic buoys, to ambient noise levels. We used vessel-tracking data from the Automatic Identification System to quantify acoustic signatures of large commercial vessels. On the basis of these integrated sound fields, median signal excess (the difference between the signal-to-noise ratio and the assumed recognition differential) for contact-calling right whales was negative (-1 dB) under current ambient noise levels and was further reduced (-2 dB) by the addition of noise from ships. Compared with potential communication space available under historically lower noise conditions, calling right whales may have lost, on average, 63-67% of their communication space. One or more of the 89 calling whales in the study area was exposed to noise levels ≥120 dB re 1 μPa by ships for 20% of the month, and a maximum of 11 whales were exposed to noise at or above this level during a single 10-min period. These results highlight the limitations of exposure-threshold (i.e., dose-response) metrics for assessing chronic anthropogenic noise effects on communication opportunities. Our methods can be used to integrate chronic and wide-ranging noise effects in emerging ocean-planning forums that seek to improve management of cumulative effects of noise on marine species and their habitats. Los efectos de la exposición crónica a niveles cada vez mayores de ruido submarino inducido por humanos sobre poblaciones de animales marinos dependientes del sonido para comunicarse están poco entendidos. Buscamos desarrollar métodos para cuantificar los efectos del enmascaramiento de la comunicación asociados con sonidos inducidos por humanos sobre el llamado de contacto de ballenas francas (Eubalaena glacialis) en un área ecológicamente relevante (∼ 10,000 km 2 ) y período de tiempo (tiempo pico de alimentación). Utilizamos un conjunto de grabadoras acústicas autónomas, temporales, montadas en el fondo en el Santuario Marino Nacional Banco Stellwagen para monitorear los niveles de sonido ambiental, medir los niveles de sonido asociados con embarcaciones y detectar y localizar llamadas de ballenas. Relacionamos la velocidad del viento, registrada por boyas oceanográficas regionales, con los niveles de sonido ambiental. Utilizamos datos de embarcaciones rastreadoras del Sistema de Identificación Automática para cuantificar las sintonías de embarcaciones comerciales mayores. Con base en estos campos de sonido integrados, la mediana del exceso de señal (la diferencia entre la relación señal-ruido y el diferencial de reconocimiento asumido) para contactar ballenas francas llamadoras fue negativo (-1 dB) bajo niveles de sonido ambiental actuales y disminuy6 (-2 dB) con la adición del ruido de los barcos. En comparación con el espacio de comunicación potencial disponible bajo condiciones de ruido históricamente más bajas, las ballenas pueden haber perdido, en promedio 63-67% de su espacio de comunicación. Una o más de las 189 ballenas llamadoras en el área de estudio estuvieron expuestas a niveles de ruido ≥120dB re1μPa de barcos durante 20% del mes, (y un máximo de 11 ballenas estuvo expuesto a ruido en o por arriba de este nivel durante un solo período de 10 minutos. Estos resultados resaltan las limitaciones de las medidas de exposición-umbral (i.e., dosis-respuesta) para evaluar los efectos del ruido antropogénico crónico sobre las oportunidades de comunicación. Nuestros métodos pueden ser utilizados para integrar los efectos de ruido crónico y de amplio rango en los foros emergentes sobre planeación marina que buscan mejorar el manejo de los efectos acumulativos del ruido sobre especies marinas y sus hábitats.
The global COVID-19 pandemic caused a sharp decline in vessel traffic in many areas around the world, including vessel-based tourism throughout Alaska, USA in 2020. Marine vessel traffic has long ...been known to affect the underwater acoustic environment with direct and indirect effects on marine ecological processes. Glacier Bay National Park in southeastern Alaska has monitored underwater sound since 2000. We used continuous, calibrated hydrophone recordings to examine 2020 ambient sound levels compared with previous years: 2018, the most recent year with data available, and 2016 for historical perspective. Park tourism occurs mainly in May–September. Overall, the number of vessel entries in Glacier Bay was 44–49% lower in 2020 (2020:
n
= 1,831; 2018:
n
= 3,599; 2016:
n
= 3,212) affecting all vessel classes, including the complete absence of cruise ships and only three tour vessel trips. In all years, we found clear seasonal and diurnal patterns in vessel generated noise, focused from 06:00 to 20:00 local time (LT) in the summer months. Broadband (17.8–8,910 Hz) sound levels in the 2020 Visitor Season were 2.7 dB lower than 2018 and 2.5 dB lower than 2016. Focusing on morning (06:00–09:00 LT) and afternoon (15:00–18:00 LT) time-blocks when tour vessels and cruise ships enter and exit Glacier Bay, median broadband sound levels were 3.3–5.1 dB lower in 2020 than prior years. At the 95th percentile levels, morning and afternoon peak times in 2020 were 6.3–9.0 dB quieter than previous years. A 3 dB decline in median sound level in the 125 Hz one-third octave band in 2020 reflects a change in medium and large vessel noise energy and/or harbor seal vocalizations. Our results suggest that all types of vessels had a role in the quieter underwater sound environment in 2020, with the combined acoustic footprint of tour vessels and cruise ships most evident in the decrease in the 95th percentile loudest sounds. This and other descriptions of the pandemic-induced quiet, and the gradual return to increased activity, can help inform efforts to improve existing methods to mitigate vessel noise impacts and maintain the ecological integrity of marine protected areas.
Animal behavior is motivated by the fundamental need to feed and reproduce, and these behaviors can be inferred from spatiotemporal variations in biological signals such as vocalizations. Yet, ...linking foraging and reproductive effort to environmental drivers can be challenging for wide‐ranging predator species. Blue whales are acoustically active marine predators that produce two distinct vocalizations: song and D calls. We examined environmental correlates of these vocalizations using continuous recordings from five hydrophones in the South Taranaki Bight region of Aotearoa New Zealand to investigate call behavior relative to ocean conditions and infer life history patterns. D calls were strongly correlated with oceanographic drivers of upwelling in spring and summer, indicating associations with foraging effort. In contrast, song displayed a highly seasonal pattern with peak intensity in fall, which aligned with the timing of conception inferred from whaling records. Finally, during a marine heatwave, reduced foraging (inferred from D calls) was followed by lower reproductive effort (inferred from song intensity).
Our work links animal behavior and oceanography to provide insights into species life history and investigate the impacts of environmental change. We examine environmental correlates of blue whale vocalization patterns in Aotearoa New Zealand. Our results demonstrate the vulnerability of marine predator populations to marine heatwaves due to the links between environmental factors that control prey availability, foraging effort, and reproductive effort.
In 2006, we used the U.S. Coast Guard's Automatic Identification System (AIS) to describe patterns of large commercial ship traffic within a U.S. National Marine Sanctuary located off the coast of ...Massachusetts. We found that 541 large commercial vessels transited the greater sanctuary 3413 times during the year. Cargo ships, tankers, and tug/tows constituted 78% of the vessels and 82% of the total transits. Cargo ships, tankers, and cruise ships predominantly used the designated Boston Traffic Separation Scheme, while tug/tow traffic was concentrated in the western and northern portions of the sanctuary. We combined AIS data with low-frequency acoustic data from an array of nine autonomous recording units analyzed for 2 months in 2006. Analysis of received sound levels (10-1000 Hz, root-mean-square pressure re 1 μPa ± SE) averaged 119.5 ± 0.3 dB at high-traffic locations. High-traffic locations experienced double the acoustic power of less trafficked locations for the majority of the time period analyzed. Average source level estimates (71-141 Hz, root-mean-square pressure re 1 μPa ± SE) for individual vessels ranged from 158 ± 2 dB (research vessel) to 186 ± 2 dB (oil tanker). Tankers were estimated to contribute 2 times more acoustic power to the region than cargo ships, and more than 100 times more than research vessels. Our results indicate that noise produced by large commercial vessels was at levels and within frequencies that warrant concern among managers regarding the ability of endangered whales to maintain acoustic contact within greater sanctuary waters.
The Gulf of Mexico ecosystem represents the intersection between high marine biodiversity and extensive human use and impact. Anthropogenic marine activities are prominent in the Gulf, prompting ...concern regarding impacts of chronic elevated noise throughout the marine ecosystem. Since sound is a critical component of the marine environment and many marine animals in the Gulf utilize sound in different aspects of their life history, their basic ecology may be negatively affected by elevated anthropogenic noise. While there are data gaps regarding the impacts of noise on marine organisms, it is crucial to understand current ambient noise conditions to evaluate the implications of noise for the Gulf ecosystem. Ambient noise measurements provide a mechanism by which to sample the cumulative acoustic activity of an ecosystem, and holistically evaluate biotic, environmental, and human-induced acoustic contributions to the overall environment. In this study, acoustic data were collected at 7 sites in the northeastern Gulf of Mexico between July 2010 and February 2012. Ambient noise is presented in 3 frequency bands (low frequency 10-500 Hz, mid-frequency 500-1000 Hz, and high frequency 1000-3150 Hz), with median sound levels of 112, 90, and 93 dB (re 1 muPa), respectively. Abiotic and anthropogenic noise sources significantly contributed to the ambient noise environment; however, seismic survey noise dominated the noise environment and chronically elevated noise levels across several paramount marine habitats. This study describes current noise conditions across the Gulf of Mexico with an intent to inform noise management strategies and investigate the potential ecological implications of elevated ambient noise.
Vessel-generated underwater noise can affect humpback whales, harbor seals and other marine mammals by decreasing the distance over which they can communicate and detect predators and prey. Emerging ...analytical methods allow marine protected area managers to use biologically relevant metrics to assess vessel noise in the dominant frequency bands used by each species. Glacier Bay National Park (GBNP) in Alaska controls summer visitation with daily quotas for vessels ranging from cruise ships to yachts and skiffs. Using empirical data (weather, AIS vessel tracks, marine mammal survey data and published behavioral parameters) we simulated the movements and acoustic environment of whales and seals on three days with differing amounts of vessel traffic and natural ambient noise. We modeled communication space (CS) to compare the area over which a vocalizing humpback whale or harbor seal could communicate with conspecifics in the current ambient noise environment (at 10-min intervals) relative to how far it could communicate under naturally quiet conditions, known as the reference ambient noise condition (RA). RA was approximated from the quietest 5th percentile noise statistics based on a year (2011) of continuous audio data from a hydrophone in GBNP, in the frequency bands of whale and seal sounds of interest: humpback “whup” calls (50-700 Hz, 143 dB re 1 µPa source level, SL); humpback song (224-708 Hz, 175 dB SL), and harbor seal roars (40-500 Hz, 144 dB SL). Results indicate that typical summer vessel traffic in GBNP causes substantial CS losses to singing whales (reduced by 13-28%), calling whales (18-51%) and roaring seals (32-61%), especially during daylight hours and even in the absence of cruise ships. Synchronizing the arrival and departure timing of cruise ships did not affect CS for singing whales, but restored 5 – 12% of lost CS for roaring seals and calling whales, respectively. Metrics and visualizations like these create a common currency to describe and explore methods to assess and mitigate anthropogenic noise. Important next steps toward facilitating effective conservation of the underwater sound environments will involve putting modeling tools in the hands of marine protected area managers for ongoing use.
This Letter proposes a frequency scaling for processing, storing, and sharing high-bandwidth, passive acoustic spectral data that optimizes data volume while maintaining reasonable data resolution. ...The format is a hybrid that uses 1 Hz resolution up to 455 Hz and millidecade frequency bands above 455 Hz. This hybrid is appropriate for many types of soundscape analysis, including detecting different types of soundscapes and regulatory applications like computing weighted sound exposure levels. Hybrid millidecade files are compressed compared to the 1 Hz equivalent such that one research center could feasibly store data from hundreds of projects for sharing among researchers globally.
In September and October 2011, a seismic survey took place in Baffin Bay, Western Greenland, in close proximity to a marine protected area (MPA). As part of the mitigation effort, five bottom-mounted ...marine acoustic recording units (MARUs) collected data that were used for the purpose of measuring temporal and spectral features from each impulsive event, providing a high-resolution record of seismic reverberation persistent after the direct impulse. Results were compared with ambient-noise levels as computed after the seismic survey to evidence that as a consequence of a series of repeating seismic impulses, sustained elevated levels create the potential for masking.
In the original paper JASA Express Lett. 1(1), 011203 (2021), a method for processing, storing, and sharing high-bandwidth, passive acoustic spectral data that optimizes data volume while maintaining ...reasonable data resolution was proposed. The format was a hybrid that uses 1-Hz resolution up to 455 Hz and millidecade frequency bands above 455 Hz. The choice of 455 Hz was based on a method of computing the edge frequencies of millidecade bands that is not compatible with summing millidecades to decidecades. This has been corrected. The new transition frequency is the first frequency with a millidecade with greater than 1 Hz, 435 Hz.
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