There are substantial concerns that increasing levels of anthropogenic noise in the oceans may impact aquatic animals. Noise can affect animals physically, physiologically and behaviourally, but one of the most obvious effects is interference with acoustic communication. Acoustic communication often plays a crucial role in reproductive interactions and over 800 species of fish have been found to communicate acoustically. There is very little data on whether noise affects reproduction in aquatic animals, and none in relation to acoustic communication. In this study we tested the effect of continuous noise on courtship behaviour in two closely-related marine fishes: the two-spotted goby (Gobiusculus flavescens) and the painted goby (Pomatoschistus pictus) in aquarium experiments. Both species use visual and acoustic signals during courtship. In the two-spotted goby we used a repeated-measures design testing the same individuals in the noise and the control treatment, in alternating order. For the painted goby we allowed females to spawn, precluding a repeated-measures design, but permitting a test of the effect of noise on female spawning decisions. Males of both species reduced acoustic courtship, but only painted gobies also showed less visual courtship in the noise treatment compared to the control. Female painted gobies were less likely to spawn in the noise treatment. Thus, our results provide experimental evidence for negative effects of noise on acoustic communication and spawning success. Spawning is a crucial component of reproduction. Therefore, even though laboratory results should not be extrapolated directly to field populations, our results suggest that reproductive success may be sensitive to noise pollution, potentially reducing fitness.

The structure and organization of acoustic signals arise through evolutionary processes and adaptive pressures on each species. During learning, natural or anthropogenic factors, such as high noise levels in urban areas, pose challenges to acoustic communication in birds. Many species adjust their acoustic signals to higher noise levels by increasing the frequency of vocalizations. The objectives of this study were to compare the dominant frequency of songs among birds dwelling in forest fragments distant from and near to urban areas, establish correlations between the dominant frequency of song and noise levels in these environments and verified the difference of response between oscines, suboscines and non-passerines. We recorded vocalizations of birds between July/2013 and November/2014 in four forest fragments, two of them near and two distant from urban areas. We used Audacity software to measure the dominant frequency. We measured the ambient noise by a calibrated sound pressure level meter in decibels (dBA) in each of the forest fragments. We analyzed 3740 vocalizations of nine tropical bird species. Forest fragments near to urban areas have higher noise levels than more distant forest fragments. Eight of nine studied species presented higher dominant frequencies of songs in forest fragments near to urban areas. Only one species, Myiothlypis flaveola, did not change the dominant frequency of song between the four analyzed forest fragments. The difference in dominant frequency between the forest fragments distant and closer to the urban areas did not vary between oscines, suboscines and non-passerines. Eight tropical birds exhibited higher dominant frequencies of song in forest fragments near urban areas with high level of ambient noise. Oscine, suboscine and non-passerine showed song variations. Bird species that have differences in the vocalization dominant frequency can be used in environmental monitoring and in ethological studies, as they are sensitive to high noise levels.Noise pollution caused by the vehicular traffic and urbanization are correlates with changes in the vocalization of tropical birds in forest fragments.

Previous studies reported that some species of the family Ceratophryidae are able to produce sounds during premetamorphic tadpole stages. We have now determined the effects of the cholinesterase-inhibiting insecticide chlorpyrifos (CPF) on sounds emitted by tadpoles of Ceratophrys ornata. Tadpoles were exposed individually in order to evaluate the progression of effects. Effects on sound production were complemented with common ecotoxicological endpoints (mortality, behavior, abnormalities and growth inhibition). C. ornata was found to be more sensitive than other native (= 67%, 50%) and non-native species (= 75%, 100%) considering lethal and sublethal endpoints, respectively. Effects on sounds appear along with alterations in swimming, followed by the presence of mild, then severe abnormalities and finally death. Therefore, sound production may be a good biomarker since it anticipates other endpoints that are also affected by CPF. Ceratophrys ornata is a promising new model species in ecotoxicology.

The impact of boat related noise on marine life is a subject of concern, particularly for fish species that utilize acoustic communication for spawning purposes. The goal of this study was to quantify and examine the risk of boat noise on fish acoustic communication by performing acoustic monitoring of the May River, South Carolina (USA) from February to November 2013 using DSG-Ocean recorders. The number of boats detected increased from the source to the mouth with the highest detections near the Intracoastal Waterway (ICW). Boat noise frequency ranges overlapped with courtship sounds of silver perch (Bairdiella chrysoura), black drum (Pogonias cromis), oyster toadfish (Opsanus tau), spotted seatrout (Cynoscion nebulosus), and red drum (Sciaenops ocellatus). In the May River estuary, red drum may experience the greatest risk of auditory masking because of late afternoon choruses (21% time overlap with boat noise) and only one spawning location near the noisy ICW.

Sound-sensitive organisms are abundant on coral reefs. Accordingly, experiments suggest that boat noise could elicit adverse effects on coral reef organisms. Yet, there are few data quantifying boat noise prevalence on coral reefs. We use long-term passive acoustic recordings at nine coral reefs and one sandy comparison site in a marine protected area to quantify spatio-temporal variation in boat noise and its effect on the soundscape. Boat noise was most common at reefs with high coral cover and fish density, and temporal patterns reflected patterns of human activity. Boat noise significantly increased low-frequency sound levels at the monitored sites. With boat noise present, the peak frequencies of the natural soundscape shifted from higher frequencies to the lower frequencies frequently used in fish communication. Taken together, the spectral overlap between boat noise and fish communication and the elevated boat detections on reefs with biological densities raises concern for coral reef organisms.

Marine traffic is the most pervasive underwater anthropogenic noise pollution which can mask acoustic communication in marine mammals and fish, but its effect in marine invertebrates remains unknown. Here, we performed an at sea experiment to study the potential of shipping noise to mask and alter lobster acoustic communication. We used hydrophones to record buzzing sounds and accelerometers to detect lobster carapace vibrations (i.e. the buzzing sounds' sources). We demonstrated that male individuals produced carapace vibrations under various ambient noise conditions, including heavy shipping noise. However, while the associated waterborne buzzing sounds could be recorded under natural ambient noise levels, they were masked by shipping noise. Additionally, lobsters significantly increased their call rates in presence of shipping noise, suggesting a vocal compensation due to the reduction of intraspecific communication. This study reports for the first time the potential acoustic masking of lobster acoustic communication by chronic anthropogenic noise pollution, which could affect ecologically important behaviors.

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.

The aim of this study is to characterize the background noise and abiotic and anthropogenic sound sources in the sector with greater anthropogenic use of the Cananéia estuary. The results show that the relative amplitude of background noise decreased with the increase of frequency range, and was higher with greater number of vessels, wind speed and during flood tide. Weekends and vacation periods were shown to be important dates during which background noise increased in the region. The influence of the tide and the wind speed on the relative amplitude was dependent on the frequency range analyzed. Therefore, both abiotic and anthropogenic sound sources were observed to be important factors regarding an increase in background noise in Cananéia. The importance of the continuity of vessel regulation in the region and of future studies that identify whether such noises alter parameters from the sound repertoire of the cetacean species in the region.