A Gulf in lockdown: How an enforced ban on recreational vessels increased dolphin and fish communication ranges

Navigating noisy waters: A review of field studies examining anthropogenic noise effects on wild fisha)

Anthropogenic noise is globally increasing in aquatic ecosystems, and there is concern that it may have adverse consequences in many fish species, yet the effects of noise in field settings are not well understood. Concern over the applicability of laboratory-conducted bioacoustic experiments has led to a call for, and a recent increase in, field-based studies, but the results have been mixed, perhaps due to the wide variety of techniques used and species studied. Previous reviews have explored the behavioral, physiological, and/or anatomical costs of fish exposed to anthropogenic noise, but few, if any, have focused on the field techniques and sound sources themselves. This review, therefore, aims to summarize, quantify, and interpret field-based literature, highlight novel approaches, and provide recommendations for future research into the effects of noise on fish.

A Quieter Ocean: Experimentally Derived Differences in Attentive Responses of Tursiops truncatus to Anthropogenic Noise Playbacks before and during the COVID-19-Related Anthropause

The effects of anthropogenic noise continue to threaten marine fauna, yet the impacts of human-produced sound on the broad aspects of cognition in marine mammals remain relatively understudied. The shutdown of non-essential activities due to the COVID-19-related anthropause created an opportunity to determine if reducing levels of oceanic anthropogenic noise on cetaceans affected processes of sensitization and habituation for common human-made sounds in an experimental setting. Dolphins at Dolphin Quest Bermuda were presented with three noises related to human activities (cruise ship, personal watercraft, and Navy low-frequency active sonar) both in 2018 and again during the anthropause in 2021 via an underwater speaker. We found that decreased anthropogenic noise levels altered dolphin responses to noise playbacks. The dolphins spent significantly more time looking towards the playback source, but less time producing burst pulse and echolocation bouts in 2021. The dolphins looked towards the cruise ship sound source significantly more in 2021 than 2018. These data highlight that different sounds may incur different habituation and sensitization profiles and suggest that pauses in anthropogenic noise production may affect future responses to noise stimuli as dolphins dishabituate to sounds over time.

Three-dimensional anthropogenic underwater noise modeling in an Arctic fjord for acoustic risk assessment

Sea-ice covering is drastically declining in the Arctic, opening new maritime routes and thus introducing underwater noise pollution in nearly pristine acoustic environments. Evaluating underwater noise pollution requires good acoustic propagation modeling to predict sound exposure levels. However, underwater noise modeling for acoustic risk assessments has often been carried out using simplistic propagation models, which approximate a 3D propagation in several planes (Nx2D), instead of using full 3D propagation models. However, Nx2D propagation models are impractical for winding geography and steep bathymetry as found in Arctic fjords. The purpose of this study is to estimate disturbance and masking effects on Arctic animal species from shipping noises, modeled through a traditional Nx2D BELLHOP model and a full 3D BELLHOP model. Classical Nx2D propagation modeling largely underestimates the anthropogenic noise footprint in Arctic fjords compared to using a full 3D propagation model.

COVID-19 lockdown has indirect, non-equivalent effects on activity patterns of Reeves's Pheasant (Syrmaticus reevesii) and sympatric species

The outbreak of the COVID-19 pandemic has brought massive shifts in human activities through a global blockade, directly affecting wildlife survival. However, the indirect impacts of changes in human activities are often easily overlooked. We conducted surveys of Reeves's Pheasant (Syrmaticus reevesii) and its sympatric species by camera traps in forest-type nature reserves in three different scenarios: pre-lockdown, lockdown and post-lockdown. An increase in livestock activities observed during the lockdown and post-lockdown period in our study area provided us an opportunity to investigate the indirect impact of the lockdown on wildlife. The pre-lockdown period was used as a baseline to compare any changes in trends of relative abundance index, activity patterns and temporal spacing of targeted species and livestock. During the lockdown period, the relative abundance index of livestock increased by 50% and there was an increase in daytime activity. Reeves's Pheasant showed avoidance responses to almost all sympatric species and livestock in three different periods, and the livestock avoidance level of Reeves's Pheasant during the lockdown period was significantly and positively correlated with the relative abundance index of livestock. Species-specific changes in activity patterns of study species were observed, with reduced daytime activities of Hog Badger and Raccoon Dog during and after the confinement periods. This study highlights the effect of the COVID-19 lockdown on the responses of wildlife by considering the changes in their temporal and spatial use before, during and after lockdown. The knowledge gained on wildlife during reduced human mobility because of the pandemic aids in understanding the effect of human disturbances and developing future conservation strategies in the shared space, to manage both wildlife and livestock.

Comparison of the marine soundscape before and during the COVID-19 pandemic in dolphin habitat in Sarasota Bay, FL

During the COVID-19 pandemic, changes in vessel activity and associated noise have been reported globally. Sarasota Bay is home to a large and increasing number of recreational vessels as well as a long-term resident community of bottlenose dolphins, Tursiops truncatus. Data were analyzed from two hydrophones to compare the soundscape during the COVID-19 pandemic to previous years (March-May 2020 and 2018/2019). Hourly metrics were calculated: vessel passes, 95th percentile sound levels [125 Hz and 16 kHz third octave bands (TOBs), and two broader bands: 88-1122 Hz and 1781-17 959 Hz], and dolphin whistle detection to understand changes in vessel activity and the effect on wildlife. Vessel activity increased during COVID-19 restrictions by almost 80% at one site and remained the same at the other site. Of the four sound level measures, only the 125 Hz TOB and 88-1122 Hz band increased with vessel activity at both sites, suggesting that these may be appropriate measures of noise from rapid pass-bys of small vessels in very shallow (<10 m) habitats. Dolphin whistle detection decreased during COVID-19 restrictions at one site but remained the same at the site that experienced increased vessel activity. The results suggest that pandemic effects on wildlife should not be viewed as homogeneous globally.

A systematic scoping review of environmental and socio-economic effects of COVID-19 on the global ocean-human system

The global outbreak of the coronavirus disease 2019 (COVID-19) has strongly affected human lives. The restrictions taken to slow down the spread of the virus impact socio-economic activities and the environment. A comprehensive review of these COVID-19 impacts on the ocean-human system is lacking. The current study fills this gap by synthesizing the environmental and socio-economic effects of the COVID-19 pandemic on the global ocean by conducting a systemic scoping review of 92 published articles. From a geospatial perspective, the studies covered a total of 37 countries, mainly from Asia, Europe, and North America, with a particular focus on the Indian Ocean and the Mediterranean Sea. From an environmental perspective, both positive and negative effects on global oceans were summarized. Notably, improved coastal water quality and reduced underwater noise were reported. On the other hand, the increasing COVID-19-related medical waste such as personal protective equipment leads to severe pollution, which threatens the marine ecosystem and wildlife. From a socioeconomic perspective, the impacts of the pandemic were negative throughout with marine tourism and the fishery industry being severely disrupted. Coastal communities suffered from loss of income, unemployment, inequalities and health problems. The COVID-19 pandemic offers an opportunity for transformation of management and economic practices in order to save our ocean and boost progress towards Sustainable Development Goal 14 (SDG 14). Future research should include other sectors such as marine biodiversity, marine renewable energy, climate change, and blue economy development of Small Island Developing States. Effective policies and strategies across land and ocean around the world need to be developed and implemented to enhance resilience of the human-ocean system and to achieve post-pandemic global sustainable ocean development.

Minimal COVID-19 quieting measured in the deep offshore waters of the U.S. Outer Continental Shelf

Using a 2-year time series (2019-2020) of 1-min sound pressure level averages from seven sites, the extension of COVID-related quieting documented in coastal soundscapes to deep (approximately 200-900 m) waters off the southeastern United States was assessed. Sites ranged in distance to the continental shelf break and shipping lanes. Sound level decreases in 2020 were observed at sites closest to the shelf break and shipping lanes but were inconsistent with the timing of shipping changes related to a COVID-19 slowdown. These observations are consistent with increased numbers of vessel tracks in 2020 compared to 2019 at a majority of sites.

Boat noise impacts Lusitanian toadfish breeding males and reproductive outcome

Anthropogenic noise is a growing threat to marine organisms, including fish. Yet very few studies have addressed the impact of anthropogenic noise on fish reproduction, especially in situ. In this study, we investigated the impacts of boat noise exposure in the reproductive success of wild Lusitanian toadfish (Halobatrachus didactylus), a species that relies on advertisement calls for mate attraction, using behavioural, physiological and reproductive endpoints. Two sets of artificial nests were deployed in the Tagus estuary and exposed to either ambient sound or boat noise during their breeding season. Toadfish males spontaneously used these nests to breed. We inspected nests for occupation and the presence of eggs in six spring low tides (in two years) and assessed male vocal activity and stress responses. Boat noise did not affect nest occupation by males but impacted reproductive success by decreasing the likelihood of receiving eggs, decreasing the number of live eggs and increasing the number of dead eggs, compared to control males. Treatment males also showed depressed vocal activity and slightly higher cortisol levels. The assessment of oxidative stress and energy metabolism-related biomarkers revealed no oxidative damage in noise exposed males despite having lower antioxidant responses and pointed towards a decrease in the activity levels of energy metabolism-related biomarkers. These results suggest that males exposed to boat noise depressed their metabolism and their activity (such as parental care and mate attraction) to cope with an acoustic stressor, consistent with a freezing defensive response/behaviour. Together, our study demonstrates that boat noise has severe impacts on reproductive fitness in Lusitanian toadfish. We argue that, at least fishes that cannot easily avoid noise sources due to their dependence on specific spawning sites, may incur in significant direct fitness costs due to chronic noise exposure.

Impact of COVID-19 lockdown on aquatic environment and fishing community: Boon or bane?

COVID-19 pandemic is a serious threat for mankind having an extensive socio-economic impact. However, it is considered as an unfortunate event with some positive environmental effects where nature is retrieving itself. The water quality index in different places of the world was reported to be improved during the lockdown, which in turn whipped up the regenerative process of fishes, sea turtles, marine mammals, and aquatic birds. Additionally, ecologically sensitive areas such as mangroves and coral reefs were also seen rejuvenating during COVID-19 seal off. But these favourable implications are temporary as there is an unexpected surge in plastic waste generation in the form of PPE kits, face masks, gloves, and other healthcare equipment. Moreover, the outbreak of the pandemic resulted in the complete closure of fishing activities, decline in fish catch, market disruption, and change in consumer preference. To address these multidimensional effects of the COVID-19 pandemic, government organizations, NGOs, and other concerned authorities should extend their support to amplify the positive impacts of the lockdown and reduce the subsequent pollution level while encouraging the fisheries sector.

Sounding the Call for a Global Library of Underwater Biological Sounds

Aquatic environments encompass the world’s most extensive habitats, rich with sounds produced by a diversity of animals. Passive acoustic monitoring (PAM) is an increasingly accessible remote sensing technology that uses hydrophones to listen to the underwater world and represents an unprecedented, non-invasive method to monitor underwater environments. This information can assist in the delineation of biologically important areas via detection of sound-producing species or characterization of ecosystem type and condition, inferred from the acoustic properties of the local soundscape. At a time when worldwide biodiversity is in significant decline and underwater soundscapes are being altered as a result of anthropogenic impacts, there is a need to document, quantify, and understand biotic sound sources–potentially before they disappear. A significant step toward these goals is the development of a web-based, open-access platform that provides: (1) a reference library of known and unknown biological sound sources (by integrating and expanding existing libraries around the world); (2) a data repository portal for annotated and unannotated audio recordings of single sources and of soundscapes; (3) a training platform for artificial intelligence algorithms for signal detection and classification; and (4) a citizen science-based application for public users. Although individually, these resources are often met on regional and taxa-specific scales, many are not sustained and, collectively, an enduring global database with an integrated platform has not been realized. We discuss the benefits such a program can provide, previous calls for global data-sharing and reference libraries, and the challenges that need to be overcome to bring together bio- and ecoacousticians, bioinformaticians, propagation experts, web engineers, and signal processing specialists (e.g., artificial intelligence) with the necessary support and funding to build a sustainable and scalable platform that could address the needs of all contributors and stakeholders into the future.

Small recreational boats: a ubiquitous source of sound pollution in shallow coastal habitats

Sound from small recreational boats spans a wide range of frequencies and source levels, but the degree to which this impacts the soundscapes of shallow coastal habitats is poorly understood. Here, long-term passive acoustic recordings at five shallow coastal sites, including two MPAs, were used to quantify spatio-temporal variation in small boat sound and its effect on the soundscape. Boats were detected almost every day at each site, irrespective of protection status, significantly elevating the low-frequency (100-800 Hz) component of the soundscape. This frequency band is used by many species for communication, orientation, and predator avoidance. Therefore, highlighting the potential for small boat sound to alter soundscapes and mask cues. Existing tools for monitoring sound pollution are targeted at sound from shipping. These data highlight that the broadband and highly variable sound emitted by small boats must be considered when evaluating anthropogenic impacts on coastal marine ecosystems worldwide.