Measuring Sound at a Cold-Water Coral Reef to Assess the Impact of COVID-19 on Noise Pollution

This study compares the noise levels at the cold-water coral Tisler reef, before and after the closure of the border between Norway and Sweden, which occurred as a direct result of the COVID-19 pandemic. The Tisler reef is a marine protected area located under a ferry “highway” that connects Norway and Sweden. Cold-water coral reefs are recognised as being important hotspots of both biodiversity and biomass, they function as breeding and nursing grounds for commercially important fish and are essential in providing ecosystem functions. Whilst studies have shown that fishery, ocean warming, and acidification threaten them, the effects of noise pollution on cold-water coral reefs remains unstudied. To study the severity of noise pollution at the Tisler reef, a long-term acoustic recorder was deployed from 29 January 2020 until 26 May 2020. From 15 March COVID-19 lockdown measures stopped passenger vessel traffic between Norway and Sweden. This study found that the overall noise levels were significantly lower after border closure, due to reduced ferry traffic, wind speeds, and sea level height. When comparing the median hourly noise levels of before vs. after border closure, this study measured a significant reduction in the 63–125 Hz 1/3 octave band noise levels of 8.94 ± 0.88 (MAD) dB during the day (07:00:00–19:59:59) and 1.94 ± 0.11 (MAD) dB during the night (20:00:00–06:59:59). Since there was no ferry traffic during the night, the drop in noise levels at night was likely driven by seasonal changes, i.e., the reduction in wind speed and sea level height when transitioning from winter to spring. Taking into account this seasonal effect, it can be deduced that the COVID-19 border closure reduced the noise levels in the 63–125 Hz 1/3 octave bands at the Tisler reef by 7.0 ± 0.99 (MAD) dB during the day. While the contribution of, and changes in biological, weather-related and geophysical sound sources remain to be assessed in more detail, understanding the extent of anthropogenic noise pollution at the Tisler cold-water coral reef is critical to guide effective management to ensure the long-term health and conservation of its ecosystem functions

Akustische Oekologie von Bartenwalen insbesondere Zwergwalen (Balaenoptera acutorostrata) unter Einbeziehung von Unterwasserlaerm

Passive acoustic approaches for studying marine mammals have developed substantially over the past decade. Advances in technology now allow data collection in remote areas and over extended timescales. The first two chapters of this thesis focused on the application of passive acoustics for monitoring migratory baleen whales in the Northwest Atlantic Ocean. The development and application of new localization algorithms showed how small-scale arrays can be used to obtain baseline data about the acoustic behavior of individuals, which will help to improve interpretation of longterm acoustic data sets. Acoustic monitoring in the Stellwagen Bank National Marine Sanctuary (SBNMS) revealed seasonal peaks of acoustic abundance for right (Eubalaena glacialis) and sei whales (Balaenoptera borealis) in spring and fall, respectively. Both species are primarily present during these two seasons and to a lesser extent in winter and summer, indicating the importance of this area as part of their migration route. Fin whales (Balaenoptera physalus) were acoustically present year-round, although song production was reduced during summer. While recorded on only a few days of the entire period, blue whale (Balaenoptera musculus) song was detected near SBNMS in three separate years. There is considerable uncertainty concerning migration routes, winter calving habitats and thus population structure of North Atlantic minke whales (Balaenoptera acutorostrata). Given that this species is still being hunted across its summer range, this uncertainty has important conservation and management implications. In chapters III-V I used 3.5 years of acoustic array data from the Gulf of Maine to describe the species' vocal repertoire, examine individual calling behavior and provide first source level estimates. Based on these data, an automatic detector was developed and applied to year-round data from several sites along the US East coast and beyond to track minke whale migration. Minke whales produced three call categories at a mean source level of 165 ± 4 dB rms re 1 μPa. Individual whales combined calls in non-random order, leading to two distinct calling patterns. Unlike other baleen whales, animals sharing the same acoustic space used different patterns simultaneously, without switching. Analysis of seasonal occurrence patterns revealed peak acoustic presence in higher latitudes during summer and fall and in lower latitudes during winter. Migration appears to follow the general direction and location of the Gulf stream in the spring and occurs in more open waters in the fall. A higher abundance of calls at offshore recording sites, suggests that there is a winter habitat located in deeper waters off the Southeastern US. Antarctic minke whales (Balaenoptera bonaerensis) have long been suggested as the likely source for the mysterious 'bioduck' signal, which is the predominant underwater sound in the Souther Ocean during austral winter. I analyzed data from the first two multi-sensor acoustic tags attached to Antarctic minke whales and was able to confirm the production of the bioduck by this species. This finding will allow the interpretation of a wealth of existing recordings, and thereby substantially improve our understanding of the distribution, abundance, and behavior of Antarctic minke whales. This is critical information for a species that lives in a rapidly changing polar environment and is subject of ongoing lethal sampling efforts. The effects of widespread anthropogenic noise in the marine environment is of increasing concern. Most discussions have centered on highly visible and regulated activities, such as seismic airguns and naval sonar. In this last chapter we showed, that humpback whale (Megaptera novaeangliae) song was reduced, concurrent with transmissions of an Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment approximately 200 km distant. This is the first time that active sonar used in fisheries science has been shown to have this effect, highlighting the importance to study and regulate the impact of all anthropogenic noise sources, including research applications. In conclusion, this thesis highlighted the suitability of passive acoustic monitoring for an increased understanding of the spatio-temporal distribution patterns and behavior of highly mobile and little studied baleen whales. In particular, it considerably improved current knowledge about the acoustic ecology and spatio-temporal distribution of minke whales.Die Erforschung von Meeressäugern mittels passiv akustischer Methoden hat sich im letzten Jahrzehnt enorm weiterentwickelt. Technologische Fortschritte erlauben nun die Datensammlung in entlegenen Gebieten und über stark verlängerte Zeiträume. Die ersten zwei Kapitel dieser Studie sind der Anwendung passiv akustischer Methoden für die Beobachtung von Bartenwalen im Nordwestatlantik gewidmet. Die Entwicklung und Anwendung neuer Lokalisationsalgorithmen verdeutlicht in diesem Zusammenhang, wie kleinskalige Hydrophonanordnungen genutzt werden können, um fundamentale Daten über das akustische Verhalten von Individuen zu erfassen. Diese Daten liefern grundlegende Informationen für die weiterführende Interpretation akustischer Langzeitdaten. Das akustische Monitoring im Stellwagen Bank National Marine Sanctuary (SBNMS) ergab zwei deutliche saisonale Höhepunkte in der akustischen Präsenz von Glattwalen (Eubalaena glacialis) im Frühjahr und Seiwalen (Balaenoptera borealis) im Herbst in diesem Gebiet. Beide Arten sind besonders zu diesen beiden Jahreszeiten, und weniger häufig im Sommer und Winter, akustisch präsent. Dieses zeitliche Verteilungsmuster belegt die Bedeutung des Gebietes als Teil der saisonalen Wanderungsroute beider Arten. Finnwale (Balaenoptera physalus) waren ganzjährig akustisch präsent, wenngleich die Häufigkeit ihrer akustischen Signale im Sommer reduziert war. Blauwalgesang (Balaenoptera musculus) konnte zwar nur an wenigen Tagen, jedoch in drei verschiedenen Jahren in den akustischen Aufzeichnungen aus diesem Gebiet nachgewiesen werden. Bezüglich der Wanderungsrouten und den Überwinterungs-, und Fortpflanzungsgebieten und demzufolge auch der Populationsstruktur des Nordatlantischen Zwergwals (Balaenoptera acutorostrata), existieren grosse Wissenslücken. Dieses fehlende Wissen hat besondere Bedeutung für den Schutz und das Management einer Art, die in ihren Nahrungsgründen im Sommer noch immer bejagt wird. Basierend auf 3.5 Jahren akustischer Daten aus dem Gulf of Maine, beschreibe ich in den Kapiteln III-V das akustische Repertoire, untersuche individuelle Rufmuster und liefere erste Messungen für den akustischen Sendepegel diese Art. Auf diesen Daten aufbauend wurde ein automatischer Detektor entwickelt, welcher für die Analyse ganzjähriger Daten von verschiedenen Orten entlang der USamerikanischen Ostküste eingesetzt wurde, um die jährliche Wanderung dieser Art zu untersuchen. Zwergwale produzieren 3 verschiedene Ruftypen mit einem Sendepegel von 165 ± 4 dB rms re 1 μPa. Dabei werden die Rufe nicht nach dem Zufallsprinzip kombiniert und es konnten zwei verschiedene Rufsequenzen identfiziert werden. Im Gegensatz zu anderen Bartenwalen, wurden beide Sequenzen simultan benutzt, wobei Individuen jedoch nicht das jeweilige Rufmuster änderten. Im Sommer waren Zwergwale in höheren Breitengraden und im Winter in eher tropischen und subtropischen Gebieten akustisch präsent. Im Frühjahr scheint die Wanderung der generellen Richtung und Position des Golfstroms zu folgen, während tiefere Gewässer auf der Wanderung in die Wintergründe bevorzugt werden. Ein erhöhtes Vorkommen von Rufen in tieferen Gewässern vor der Südostküste der USA legen die Existenz von Wintergründen in diesen Gebieten nahe. Antarktische Zwergwale (Balaenoptera bonaerensis) wurden lange als die mögliche Quelle des 'bioduck' Signals, welches die dominante Schallquelle im Südpolarmeer im Winter darstellt, impliziert. Die Analyse der ersten Datevon von akustischen Tags, bestätigen diese Annahme. Diese Ergebnisse erlauben eine neue Interpretation von bereits vorhandenen akustischen Langzeitaufnahmen und werden das Wissen um die Verteilung, den Bestand und das Verhalten dieser Art enorm erweitern. Diese Informationen sind besonders kritisch im Hinblick auf dramatische Veränderungen im polaren Lebensraum dieser Art, die ebenfalls weiterhin aktiv bejagt wird. Die Auswirkungen von weit verbreitetem Unterwasserlärm werden mit immer grösserer Besorgnis betrachtet. Bisher beschränkten sich die meisten Diskussionen auf bereits regulierte Aktivitäten, wie seismische- und Navy Sonarsysteme. Im letzten Kapitel dieser Studie zeigen wir die Reduktion von Buckelwalgesang (Megaptera novaeangliae) in der Folge eines Ocean Acoustic Waveguide Remote Sensing (OAWRS) Experiments in 200 km Entfernung. Dies ist das erste Mal, dass aktive Sonarsysteme der Fischereiforschung im Hinblick auf mögliche Auswirkungen auf das Verhalten mariner Säuger untersucht wurden. Die Ergebnisse verdeutlichen die Wichtigkeit, die Auswirkungen aller anthropogenen Lärmquellen, inklusive von Sonarsystemen, die für die Forschung genutzt werden, zu untersuchen. Zusammenfassend unterstreicht diese Studie die Eignung passiv akustischer Methoden für ein verbessertes Monitoring und die Vermehrung des Wissens über die raum-zeitlichen Verteilungsmuster und das Verhalten von weit wandernden, wenig erforschten Bartenwalarten. Im besonderen konnte die Studie grundlegende Fragen zur akustischen Ökologie und den saisonalen Verteilungsmustern von Zwergwalen klären

Acoustic assessment of SIMRAD EK60 high frequency echo sounder signals (120 & 200 kHz) in the context of marine mammal monitoring

The use of active high frequency echo sounders for commercial activities and marine research has been increasing in recent years. Compared to other anthropogenic noise sources, high frequency echo sounders have received little attention in terms of their potential impacts on marine life. However, while these devices typically operate at centre frequencies outside the hearing range of most marine species, recent work has demonstrated that they may produce unintended energy at lower frequencies. These lower frequencies may extend into the audible range for several species of marine mammals and have the potential to affect their behaviour (Deng et al. 2014). Given the theoretical detectability of these lower frequencies by marine mammals, both signal types have the potential to elicit behavioural responses towards them. This should be considered in environmental impact assessments of activities using these devices and when planning marine mammal monitoring studies alongside ecosystem studies using active acoustic sonar systems

Seasonal and diel patterns in singing activity of humpback whales migrating through Bermuda

Humpback whales (Megaptera novaeangliae) produce song and non-song vocalisations, which allows their presence to be detected through passive acoustic monitoring. To determine the seasonal and diel acoustic presence and acoustic behaviour of humpback whales at the migratory stopover site off Bermuda, three hydrophones were deployed between March 2018 and April 2019 on Challenger Bank and the Bermuda platform. Song was the predominant vocalisation type encountered, with 65% of song recordings containing whale chorus and a clear seasonal trend of humpback whale occurrence in the spring and winter months from late December to mid-May. A strong diel pattern in singing activity was detected. Singing activity significantly increased at night relative to the daytime (p<0.01), whilst twilight periods were characterised by intermediate levels of singing. The song structure encountered in spring 2018 consisted of 18 units, 6 themes and 5 transitional phrases. The high occurrence of whale chorus and the strong seasonal and diel patterns of male humpback whale singing activity highlights the importance of Bermuda not just on their northward migration during spring, as described historically, but also on their southward migration during winter. Bermuda therefore constitutes a two-way migratory stopover site for humpback whales. The present study also provides Bermuda’s planning authorities with better constraints on the duration and intensity of anthropogenic activities in these waters

A framework to predict, validate and review the acoustic footprints of operating tidal turbines [abstract]

A framework to predict, validate and review the acoustic footprints of operating tidal turbines [abstract

Classification for Big Dataset of Bioacoustic Signals Based on Human Scoring System and Artificial Neural Network

In this paper, we propose a method to improve sound classification performance by combining signal features, derived from the time-frequency spectrogram, with human perception. The method presented herein exploits an artificial neural network (ANN) and learns the signal features based on the human perception knowledge. The proposed method is applied to a large acoustic dataset containing 24 months of nearly continuous recordings. The results show a significant improvement in performance of the detection-classification system; yielding as much as 20% improvement in true positive rate for a given false positive rate.Comment: To be Submitted to "ICML 2013 Workshop on Machine Learning for Bioacoustics", 6 pages, 4 figure

Sperm whale presence observed using passive acoustic monitoring from gliders of opportunity

Habitat use by the endangered Mediterranean sperm whale subpopulation remains poorly understood, especially in winter. The sustained presence of oceanographic autonomous underwater vehicles in the area presents an opportunity to improve observation effort, enabling collection of valuable sperm whale distribution data, which may be crucial to their conservation. Passive acoustic monitoring loggers were deployed on vertically profiling oceanographic gliders surveying the north-western Mediterranean Sea during winter 2012-2013 and June 2014. Sperm whale echolocation 'usual click' trains, characteristic of foraging activity, were detected and classified from the recordings, providing information about the presence of sperm whales along the glider tracks. Widespread presence of sperm whales in the north-western Mediterranean Sea was confirmed. Winter observations suggest different foraging strategies between the Ligurian Sea, where mobile and scattered individuals forage at all times of day, and the Gulf of Lion, where larger aggregations target intense oceanographic features in the open ocean such as fronts and mixing events, with reduced acoustic presence at dawn. This study demonstrates the ability to successfully observe sperm whale behaviour from passive acoustic monitoring gliders. We identified possible mission design changes to optimize data collected from passive acoustic monitoring glider surveys and significantly improve sperm whale population monitoring and habitat use

Measuring sound at a cold-water coral reef to assess the impact of COVID-19 on noise pollution

This study compares the noise levels at the cold-water coral Tisler reef, before and after the closure of the border between Norway and Sweden, which occurred as a direct result of the COVID-19 pandemic. The Tisler reef is a marine protected area located under a ferry “highway” that connects Norway and Sweden. Cold-water coral reefs are recognised as being important hotspots of both biodiversity and biomass, they function as breeding and nursing grounds for commercially important fish and are essential in providing ecosystem functions. Whilst studies have shown that fishery, ocean warming, and acidification threaten them, the effects of noise pollution on cold-water coral reefs remains unstudied. To study the severity of noise pollution at the Tisler reef, a long-term acoustic recorder was deployed from 29 January 2020 until 26 May 2020. From 15 March COVID-19 lockdown measures stopped passenger vessel traffic between Norway and Sweden. This study found that the overall noise levels were significantly lower after border closure, due to reduced ferry traffic, wind speeds, and sea level height. When comparing the median hourly noise levels of before vs. after border closure, this study measured a significant reduction in the 63–125 Hz 1/3 octave band noise levels of 8.94 ± 0.88 (MAD) dB during the day (07:00:00–19:59:59) and 1.94 ± 0.11 (MAD) dB during the night (20:00:00–06:59:59). Since there was no ferry traffic during the night, the drop in noise levels at night was likely driven by seasonal changes, i.e., the reduction in wind speed and sea level height when transitioning from winter to spring. Taking into account this seasonal effect, it can be deduced that the COVID-19 border closure reduced the noise levels in the 63–125 Hz 1/3 octave bands at the Tisler reef by 7.0 ± 0.99 (MAD) dB during the day. While the contribution of, and changes in biological, weather-related and geophysical sound sources remain to be assessed in more detail, understanding the extent of anthropogenic noise pollution at the Tisler cold-water coral reef is critical to guide effective management to ensure the long-term health and conservation of its ecosystem functions

Exposure of individual harbour seals (Phoca vitulina) and waters surrounding protected habitats to acoustic deterrent noise from aquaculture

This work was funded by the European Social Fund and Scottish Funding Council as part of Developing Scotland's Workforce in the Scotland 2014–2020 European Structural and Investment Fund Programme. NDM and AF were funded by the Centre for Environment, Fisheries and Aquaculture Science (Cefas). Funding for the seal tagging was provided by the Scottish Government to the Sea Mammal Research Unit (SMRU) as part of the Marine Mammal Scientific Support Program MMSS/002/15, with additional resources from the Natural Environment Research Council (grant numbers NE/J004251/1 and SMRU1001).1. Pinniped depredation at aquaculture sites is a globally recognized problem. To mitigate depredation, the aquaculture sector uses acoustic deterrent devices (ADDs) as a non-lethal alternative to shooting pinnipeds interacting with caged finfish. However, it is unclear whether sound emissions from ADDs have the potential to also impact non-target pinnipeds at spatial scales relevant to populations. 2. Global Positioning System (GPS) tracking data from seven harbour seals tagged in a non-aquaculture context, on the west coast of Scotland, in 2017 were combined with modelled maps of ADD noise to quantify sound exposure and estimate the potential for auditory impairment. The acoustic model applied an energy flux approach across the main frequency range of ADDs (2–40 kHz). Predictions of temporary and permanent auditory threshold shifts were made using seal location data and published noise exposure criteria. The acoustic exposure of waters (10-km buffers) surrounding protected habitats (i.e. designated haul outs and Special Areas of Conservation (SACs)) on the west coast of Scotland was also assessed. 3. All tagged seals and waters surrounding 51 of 56 protected sites were predicted to be exposed to ADD noise exceeding median ambient sound levels. Temporary auditory impairment was predicted to occur in one of the seven tagged harbour seals and across 1.7% of waters surrounding protected habitats over a 24-hour period, when assuming a 100% ADD duty cycle. 4. Although the predicted risk of auditory impairment appears to be relatively low, these findings suggest that harbour seals inhabiting inshore waters off western Scotland are routinely exposed to ADD noise that exceeds median ambient sound levels. This chronic exposure risks negative consequences for individual harbour seals among the wider population in this region. The use of ADDs to mitigate pinniped depredation should be carefully considered to reduce unintended habitat-wide impacts on non-target species, including pinnipeds that are not specifically interacting with aquaculture.Publisher PDFPeer reviewe