1,720,991 research outputs found
Underwater noise assessment in the Gulf of Trieste (Northern Adriatic Sea, Italy) using an MSFD approach
No full textIn the marine environment, underwater noise is one of the most widespread input of man-made energy. Recently, the European Commission has stressed the necessity of establishing threshold levels as a target for the descriptor 11.2.1 "Continuous low frequency sounds" in the Marine Strategy Framework Directive (MSFD). In 2012, a monthly underwater noise monitoring programme was conducted in the Gulf of Trieste (Northern Adriatic Sea, Italy); the collected acoustic samples (frequency range: 10-20,000. Hz) were analysed in the 1/3 octave bands. The stations have been further clustered following the 63 and 125. Hz bands noise levels. Average SPL levels resulted similar to those previously computed for proximate areas, indicating that the Adriatic Sea sub-region experiences high noise pressure in the marine waters. In its turn this claims for a scientific and technical international cooperation, as requested by the EU programme. No seasonal variation in local noise levels has been found
Changes in whistle structure of resident bottlenose dolphins in relation to underwater noise and boat traffic
No full textThe habitat of the resident bottlenose dolphins (Tursiops truncatus) of the Cres-Losinj archipelago overlaps with routes of intense boat traffic. Within these waters, Sea Ambient Noise (SAN) was sampled across ten acoustic stations between 2007 and 2009. Data on boat presence was concurrently collected and when dolphins were sighted group behaviour was also recorded.Acoustic recordings were analysed for 1/3 octave bands. Samples containing dolphin whistles were analysed and compared with boat presence and SAN levels. Results indicate that dolphins whistle at higher frequencies in conditions of elevated low frequency noise. Conversely, they reduce maximum, delta and start frequencies and frequency modulations when noise levels increase significantly across higher frequencies. The study shows that high levels of SAN causes significant changes in the acoustic structure of dolphin whistles. Additionally, changes in whistle parameters, in the presence of boats, appear to be related to the behavioural state of the dolphin group. (C) 2016 Elsevier Ltd. All rights reserved
Characterization of small-boat noises compared with the chorus of sciaena umbra (sciaenidae)
No full textOne-year characterization of sea ambient noise in a coastal marine protected area: A management tool for inshore marine protected areas
No full textMating behaviour by the haddock (Melanogrammus aeglefinus)
No full textThis study examines the full repertoire of haddock reproductive behaviour, monitored in an aquarium for 3 months over each of two successive spawning seasons. Observations showed that male haddock were territorial and that visits to their territories by females triggered courtship behaviour, leading to spawning. Entry of females to the territories was induced by an acoustic and visual self-advertisement of displaying males, termed patrolling behaviour, exhibited for many hours each night for several months. The existence of sneaking behaviour by non-territorial males was observed for the first time for haddock and was supported by genetic data. Overall our observations are consistent with the behaviour expected from lekking species, as in the cod, a closely related species. Lekking is said to occur when non-resource-based aggregations of males are visited by females for the purpose of mating. Implications for the management of fish stocks are discussed
Four type of sounds for one winner: vocalizations during territorial behaviour in the red-mouthed goby Gobius cruentatus (Pisces, Gobiidae)
No full textDuring territorial encounters, the acoustic repertoire of Gobius cruentatus consists of four types of sound emissions: a tonal sound, a noisy tonal sound, a train of individual pulses, and a complex sound. The complex sound is made of two distinct elements, an initial tonal part followed by pulses. This is the largest acoustic repertoire described so far in gobiid fish during aggressive interaction. Sounds are emitted, mainly by the residents, when fish have already started the interaction but before the encounter is settled. Therefore, sounds seem to have a threatening function. © 2008 Springer-Verlag and ISPA
Spatial and temporal variability of sea ambient noise as an anthropogenic pressure index: the case of the Cres-Losinj archipelago, Croatia
No full textThis study monitors the spatial and temporal variability of sea ambient noise (SAN) in the Cres-Losinj archipelago from 2007 to 2009 (north-eastern Adriatic Sea, Croatia). The archipelago is an important marine habitat for many protected species, including the bottlenose dolphin (Tursiops truncatus) that is considered as vulnerable to disturbance from intense local vessel traffic. Systematic monthly sampling of SAN was carried out at ten predefined acoustic stations. Data on the presence, type and distance of vessels from these stations was also collected during sampling and vessels were allocated into four main classes. A sample of noise produced by a representative vessel of each vessel class was collected and the noise levels were extracted on the 1/3 octave band standard centre frequencies. All the recordings were analysed in terms of instantaneous sound pressure level (L-LSP, L-weighted, 63 Hz-20 kHz, root mean square fast). The equivalent continuous sound pressure levels (L-Leq) for vessel and SAN were calculated averaging the LLSP of vessel and SAN samples. Results indicate an increase of SAN levels particularly in the range of low frequencies (63 Hz-1 kHz) during the tourist season. A positive relationship was found between the spatial and temporal distribution of SAN and seasonal changes in anthropogenic pressure, in terms of vessel traffic. Potential implications for local marine life, with particular reference to bottlenose dolphins, are discussed
Locating spawning haddock (Melanogrammus aeglefinus, Linnaeus, 1758) at sea by means of sound
No full textThe sites where haddock spawn and the factors that bring the fish together to spawn at particular locations are not well known. We have located haddock in the sea by listening for the sounds this species makes during its reproductive behaviour. The characteristics of the sounds made by haddock were first examined in the aquarium. Listening was then carried out in a Norwegian fjord, where fishers had reported spawning haddock. Long sequences of repeated knocks were heard in the fjord, similar to the display sounds recorded during stereotyped reproductive behaviour in the aquarium. Rapidly repeated knocks and humming were also heard, confirming that fish were engaging in courtship. At night the sounds merged into a continuous low frequency rumble, suggesting that many haddock were present, producing sounds simultaneously. Listening for haddock sounds provides a reliable, non-invasive way of locating aggregations of spawning haddock in the sea, allowing closer definition of the spawning areas. Both fishing and exposure of haddock to man-made noise at the critical time of spawning may have deleterious effects upon reproductive success. © 2014 Elsevier B.V
Seasonal patterns and individual differences in the calls of male haddock Melanogrammus aeglefinus
No full textHaddock Melanogrammus aeglefinus males observed in captivity proved to be vocally active throughout the whole year, although the highest levels of vocal activity were reached in the spawning season between February and April. During this season, the most common type of sound consisted of sequences of regularly repeated, almost identical, double-pulsed knocks (KN). These sequences were mostly associated with a particular behaviour pattern, the patrolling display, which has previously been shown to play a key role in territoriality and spawning. Differences in the double-pulsed KNs produced by three individual males were demonstrated by two different statistical methods and it is suggested that these differences may allow individual males to be discriminated by other fish, perhaps conveying fitness-related information on the sender. Some aspects of the calls changed seasonally, perhaps reflecting observed variations in the mass of the drumming muscles. When using passive listening to locate M. aeglefinus spawning grounds, the physical characteristics of the sounds may indicate how close the individual males are to spawning
Sound features and vocal rhythms as a proxy for locating the spawning ground of Sciaena umbra in the wild
No full text1.The brown meagre (Sciaena umbra) is a demersal sciaenid fish recognized as indicative of good environmental quality and is defined as an umbrella species for the ecological community of rocky coastal habitats. Sciaena umbra is classified as a Vulnerable fish species by the International Union for Conservation of Nature (IUCN) and knowledge on the distribution of its spawning habitats is essential for its conservation. 2.Passive acoustic monitoring (PAM) is a suitable tool to monitor S. umbra distribution because of the high consistency, over space and time, of the communication sounds that this species emits during the reproductive period, with irregular or regular rhythms, or with calls merging into a chorus. 3.During the summer of 2019, the presence of this species was investigated acoustically at 40 listening points distributed along the tidal inlets that connect the Venice lagoon with the open sea. 4.Longer sounds, comprising a higher number of faster repeated pulses, were found during the chorus and were used as a proxy of spawning activity; similar sound features have been recorded in different captive Sciaenids during spawning. 5.The three inlets were classified as more or less suitable for spawning on the basis of the vocal rhythms identified, demonstrating a clear preference along a north–south gradient and indicating higher spawning activity in the internal-facing areas of the inlets, compared with the seaward-facing areas. The chorus occurred in localized areas consistently throughout the breeding season, suggesting that spawning is concentrated in preferred areas. 6.For the first time a relationship between the sound features and vocal rhythms of fish has been highlighted by an in situ study. This validates the use of the chorus as a reliable natural indicator of S. umbra breeding sites, and in turn suggests a potential non-invasive approach based on PAM for mapping the key reproductive areas of this vulnerable species in the Mediterranean Sea
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