| 1. |
- Enmar, Linda, et al.
(författare)
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A note on ADCP-based indirect observations of turbulence
- 2016
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Ingår i: Boreal environment research. - 1239-6095 .- 1797-2469. ; 21:1-2, s. 44-52
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Tidskriftsartikel (refereegranskat)abstract
- A 70-day data set from bottom-mounted ADCPs on the two sides of the Faroe-Bank Channel was analysed using the recorded flow variance and echo intensity in the deeper reaches of the passage as proxies for turbulence. A consistent picture emerged, not least since the data losses (which were ascribed to turbulence-induced activation of the fish-elimination option in the ADCP software) could be shown to co-vary with the internal M-2 tide affecting the vertical shear, which in turn proved to be correlated with the flow variance.
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| 2. |
- Mueller-Blenkle, Christina, et al.
(författare)
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A Novel Field Study Setup to Investigate the Behavior of Fish Related to Sound
- 2012
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Ingår i: The Effects of Noise on Aquatic Life. - New York : Springer-Verlag New York. - 9781441973108 - 9781441973115 ; , s. 389-391
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Konferensbidrag (refereegranskat)abstract
- There is an urgent need to obtain information on the effects of underwater sound on marine fish due to imminent policy drivers, e.g., the European Union Marine Strategy Framework Directive, on one hand and the increasingly noisy activities in the marine environment on the other. Yet studying the influence of sound, particularly on the behavior of fish, is a challenging task. Studies in tanks can suffer problems with the reflection of sound, especially at the low frequencies that are most important for fish. Studies in the field are often limited because the observation of fish is very complicated.
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| 3. |
- Mueller-Blenkle, Christina, et al.
(författare)
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Effects of pile-driving noise on the behaviour of marine fish
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Studies on the effects of offshore wind farm construction on marine life have so far focussed on behavioural reactions in porpoises and seals. The effects on fish have only very recently come into the focus of scientists, regulators and stakeholders. Pile-driving noise during construction is of particular concern as the very high sound pressure levels could potentially prevent fish from reaching breeding or spawning sites, finding food, and acoustically locating mates. This could result in longterm effects on reproduction and population parameters. Further, avoidance reactions might result in displacement away from potential fishing grounds and lead to reduced catches. However, reaction thresholds and therefore the impacts of pile-driving on the behaviour of fish are completely unknown. We played back pile-driving noise to cod and sole held in two large (40 m) net pens located in a quiet Bay in West Scotland. Movements of the fish were analysed using a novel acoustic tracking system. Received sound pressure level and particle motion were measured during the experiments. There was a significant movement response to the pile-driving stimulus in both species at relatively low received sound pressure levels (sole: 144 – 156 dB re 1μPa Peak; cod: 140 – 161 dB re 1 μPa Peak, particle motion between 6.51x10-3 and 8.62x10-4 m/s2 peak). Sole showed a significant increase in swimming speed during the playback period compared to before and after playback. Cod exhibited a similar reaction, yet results were not significant. Cod showed a significant freezing response at onset and cessation of playback. There were indications of directional movements away from the sound source in both species. The results further showed a high variability in behavioural reactions across individuals and a decrease of response with multiple exposures. This study is the first to document behavioural response of marine fish due to playbacks of pile-driving sounds. The results indicate that a range of received sound pressure and particle motion levels will trigger behavioural responses in sole and cod. The results further imply a relatively large zone of behavioural response to pile-driving sounds in marine fish. Yet, the exact nature and extent of the behavioural response needs to be investigated further. Some of our results point toward habituation to the sound. The results of the study have important implications for regulatory advice and the implementation of mitigation measures in the construction of offshore wind farms in the UK and elsewhere. First, the concerns raised about the potential effects of pile-driving noise on fish were well founded. This suggests to both regulators and developers that the costs imposed by some mitigation measures that have so far been applied following the precautionary principle go some of the way to addressing a real problem. We also suggest that our behavioural thresholds are considered in assessments of impacts of offshore wind farms in the UK and elsewhere. Mitigation measures should be further discussed developed and, if meaningful, applied especially if these could lead to a reduction of acoustic energy that is emitted into the water column. Further studies should investigate the response at critical times (e.g. mating and spawning) and the effects of pile-driving on communication behaviour. It will also be necessary to further investigate habituation to the sound to effectively manage effects of pile-driving sound on marine fish.
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| 4. |
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| 5. |
- Nilsson, Jenny A. U., 1978-
(författare)
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On methods for estimating oceanic flow
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to estimate and possibly quantify ocean flow by utilizing conventional and novel observational methods as well as model results. Motionally induced voltages, from a cable-based observational system in the Baltic Sea, were analysed to determine their utility for ocean monitoring. The data set was examined as regards the influence of single- and multi-layer flow. Correlation analyses undertaken in the first study showed that the geoelectric installation is capable of providing good estimates of the net flow across the Visby-Västervik transect. The second study focused on possible effects of multi-layer flow on the signal. Comparisons were made with tidal-gauge geostrophic flow estimates, and a good agreement was found, except for a few brief winter periods characterized by significant discrepancies. The velocity fields from a three-dimensional model showed that these events coincided with strong surface and bottom currents, and hence the attenuated voltage signal was suggested as being caused by the non-uniform velocity distribution.The third study dealt with the deep-water flow through the Understen-Märket trench. Observational data indicated that this flow could be described by applying hydraulic theory. Since the passage is narrow compared to the internal Rossby radius of deformation, rotational effects could be neglected to lowest order. The theoretical predictions proved to agree well with the observational results.The final study examined the effects of the heat flux and the wind forcing on the circulation in Bahía de Concepción, Chile, where three field surveys were undertaken during the extended austral summer 2002. Hydrographic and current measurements were compared to local tidal-gauge records. Rough estimates of the barotropic and the baroclinic flow across the transect indicated an unusual vortex circulation during periods of weak wind forcing and strong surface heating; results which were corroborated by numerical simulations.
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| 6. |
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| 7. |
- Thomsen, Frank, et al.
(författare)
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Effects of Pile Driving on the Behavior of Cod and Sole
- 2012
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Ingår i: The Effects of Noise on Aquatic Life. - New York : Springer. - 9781441973108 - 9781441973115 ; , s. 387-388
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Konferensbidrag (refereegranskat)abstract
- Studies on the effects of offshore wind farm construction on marine life have focused on behavioral reactions in porpoises and seals (Thomsen et al. 2006). The effects on fish have only very recently come into the focus of scientists, regulators, and stakeholders (Popper and Hastings 2009). Pile-driving noise during construction is of particular concern because the very high sound pressure levels (see Thomsen et al. 2006) could potentially prevent fish from reaching breeding or spawning sites, finding food, and acoustically locating mates that could result in long-term effects on reproduction and population parameters. There is also the possibility that avoidance reactions might displace fish away from potential fishing grounds that could lead to reduced catches (see, e.g., Engås et al. 1996). However, the nature and extent of behavioral reactions of marine fish due to pile driving have not been studied in controlled experiments. Therefore, the impacts of pile driving on marine fish remain unknown.
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| 8. |
- Andersson, Mathias H, et al.
(författare)
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A framework for regulating underwater noise during pile driving
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Pile driving is a common technique used during the construction of bridges, offshore wind power, and underwater infrastructure or shoreline structures. It is the process by which a foundation, beam or pole is hammered or vibrated down into the bottom, which can generate extremely loud noise that propagates throughout the surrounding water and sediment. The noise can reach such high levels that marine animals are at risk of disturbance, injury or even death.Sweden currently lacks established thresholds stating the level at which underwater noise potentially disturbs or injures marine animals. Hence, there are no guidance values for allowable underwater noise levels from noiseproducing activities to avoid serious environmental impacts. Several countries in Europe have defined thresholds for when underwater noise can result in severe negative environmental impacts as well as standards for measuring, analysing and reporting underwater noise levels.The purpose of this study is to review the scientific literature on underwater noise from pile driving and its effects on marine life. The study aims to define the noise levels that can cause injury and other negative effects and, on this basis, recommend noise levels that can be used to establish guidance values for regulating underwater noise for Swedish waters and species. The study presents examples of the factors that contribute to sound propagation in Swedish waters and how this influences the noise level from a pile strike as a function of distance at four study areas along the Swedish coast. Additionally, the study contains a thorough technical description of pile driving activities, basic underwater acoustics and noise effects on marine animals. These effects (injury and behavioral, e.g., flight, but not subtle effects) are demonstrated on representative species such as the harbour porpoise (Phocoena phocoena), Atlantic cod (Gadus morhua), Atlantic herring (Clupea harengus) and on fish larvae and eggs. The study’s authors look atthe original sources of information that other countries base their guidelines and thresholds on, so the recommendations follow scientifically determined levels rather than values that have been rounded off or otherwise altered.The study presents sound levels in three different units, each with different biological relevance to the effects caused by a pile driving activity. None of the sound levels have been frequency weighted for a specific species, as this method is not yet fully established. The first unit used is the sound pressure level SPL(peak), which is the maximum overpressure or underpressure of the noise pulse generated by the pile strike. This unit has a high relevance for behavioural effects. The sound exposure level, SEL, is the calculated energy level over a period of time and expresses the energy of the entire sound pulse. SEL is the unit most related to hearing impairing effects. SEL(ss) is the value for a single strike while SEL(cum) is the cumulative value of a determined number of pulses over a period of time. The review revealed that for Atlantic cod and Atlantic herring there are currently no studies that can be used to determine a species’ specific threshold value for injury, but studies show that loud noise can affect both species negatively. Because of this, the recommended noise levels for injury are based mainly on studies on other species exposed to pile driving noise in laboratory environments, supported by studies conducting large-scale experiments in tanks and oceans. The levels at which fish are at risk of death or sustaining serious injury to internal organs is SPL 207 dB re 1 μPa, SEL(ss) 174 dB re 1 μPa2s and SEL(cum) 204 dB re 1 μPa2s. Note that for injury in fish, the cumulative sound exposure level has higher relevance than the single-strike level as the cited studies found injuries after a certain time period of exposure. The thresholds for fish larvae and eggs are based on the fact that no negative effects were observed at exposures of up to SPL(peak) 217 dB re 1 μPa, SEL(ss) 187 dB re 1 μPa2s and SEL(cum) 207 dB re 1 μPa2s. However, there are relatively few studies on early life stages of fish. There are more species-specific studies on harbour porpoises regarding noise than there are for Atlantic cod and Atlantic herring. Nonetheless, only a few can be used to determine thresholds that will lead to injury or negative behavioural effects. The levels at which there is a risk of a temporary impact on hearing, i.e. temporary threshold shift (TTS), for the harbour porpoises is SPL(peak) 194 dB re 1 μPa, SEL(ss) 164 dB re 1 μPa2s and SEL(cum) 175 dB re 1 μPa2s. When it comes to TTS, the cumulative sound exposure level, SEL(cum), is of primary importance. However, this unit is dependent on a specific time and number of pulses. For permanent threshold shift (PTS), the level is set to SPL(peak) 200 dB re 1 μPa, SEL(ss) 179 dB re 1 μPa2s and SEL(cum) 190 dB re 1 μPa2s. The recommended level should be revised as new relevant studies are conducted.
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| 9. |
- Andersson, Mathias H., et al.
(författare)
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Displacement effects of ship noise on fish population : FP7 - Collaborative Project n° 314227 WP 4: Sensitivity of marine life to shipping noise Task 4.2.1
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ship induced noise is one of the major contributors to the elevated noise levels in the world’s oceans today. However, the knowledge about the impact on marine organisms is still scarce. Especially the effects on fish behaviour needs to be studied as fish are a fundamental part of the oceans ecosystem. Direct measurement of fish behaviour in the open sea area is technically difficult but needs to be done in order to estimate reaction thresholds and scales of any reaction. This experiment studies the long term behavioural reaction by wild cod (Gadus morhua) to ship noise and describes the character and scale of the reaction. This study took place on the Swedish west coast with a small local cod population and the area is normally without any large vessel traffic. For the ship disturbance, the Swedish Coast Guard ship KBV 032 was hired and passed thru the area nine times during three days. During the three days of ship noise exposure, the noise levels increased well above the ambient noise. The ship signature was what could be expected in terms of spectral level with most radiated noise energy between 100 - 500 Hz. The ship had a higher source level than expected (232 dB re 1μPa at 1 m, 10 - 300 Hz) but this was deliberate as the crew was asked to use the propellers in a non-optimal way to generate as much noise as possible. The result was a lot of broadband cavitation pulses generated by the ship. Then a noise footprint model was created and used in the estimates of received levels (exposure level) by the individual fish in the area based on the most probable location. It was clear in the transmission loss varied between the two sites where at the shallow site, the noise was attenuated more compared to the deep site. This is probably caused by the quite complicated propagation pattern. Also, the acoustically different bottom properties will affect the transmission loss in the area. In total, 39 cod (Gadus morhua) were caught by hand jigging and were fitted with internal acoustical tags. Bottom mounted receivers were deployed covering the area where the cod were known to inhabit. This study was designed to capture more large scale movements of hundreds of meters and not startle responses to the ship noise. Out of the 39 tagged fish, 17 and 18 fish met the set quality criterion for the short time behaviour analysis and 23 fish for long time behaviour to be included in the analysis. Some fish met the quality criteria for both the short and long term analysis. The other fish were either eaten by seals, caught by fishermen, left the area or had a malfunctioning tag. In general, the noticed reaction in terms of horizontal swimming were much smaller than expected and what the study was designed for. This results was surprising as the sound pressure levels the fish were exposed to would, based on the literature, cause a strong behaviour response in the fish. The movement was not in any large scale that would affect their energy consumption and affect their long term survival. This study was able to track fish with an accuracy of less than 10 m and estimates an interval of received noise level. This is one of the first studies of its kind that is tracking free swimming fish over a long period of time during an acoustic disturbance.
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| 10. |
- Andersson, Mathias H., et al.
(författare)
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Do Ocean-Based Wind Farms Alter the Migration Pattern in the Endangered European Silver Eel (Anguilla anguilla) Due to Noise Disturbance?
- 2012
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Ingår i: The Effects of Noise on Aquatic Life. - New York : Springer-Verlag New York. - 9781441973108 - 9781441973115 ; , s. 393-396
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Konferensbidrag (refereegranskat)abstract
- Numerous offshore wind farms have been built and will increase in the near future in the coastal areas of northern Europe. These locations are often in the direct path of migrating Anguilla anguilla (European silver eel) on their 5,000- to 6,000-km journey from Europe to the Sargasso Sea. At a certain time in their life that occurs between the ages of 6 and 20, A. anguilla start their long spawning migration. When this occurs, an irreversible physiological transformation starts in which the eyes and pectoral fins are enlarged, the skin color changes, and the digestive organs are regressed. Additionally, they stop feeding during the migration phase, which gives A. anguilla a limited amount of stored energy. If the fish are disturbed or hindered, the energy reserves might not be enough for them to reach their destination or it could, at least, result in limited spawning success. This effect could be devastating to the already highly threatened A. anguilla population that is listed as “critically endangered” in the International Union for Conservation of Nature (IUCN) red list.
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