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von Benda-Beckmann AM, Isojunno S, Zandvliet M, Ainslie MA, Wensveen PJ, Tyack PL, Kvadsheim PH, Lam FPA, Miller PJO. Modeling potential masking of echolocating sperm whales exposed to continuous 1-2 kHz naval sonar. J Acoust Soc Am 2021; 149:2908. [PMID: 33940877 DOI: 10.1121/10.0004769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
Modern active sonar systems can (almost) continuously transmit and receive sound, which can lead to more masking of important sounds for marine mammals than conventional pulsed sonar systems transmitting at a much lower duty cycle. This study investigated the potential of 1-2 kHz active sonar to mask echolocation-based foraging of sperm whales by modeling their echolocation detection process. Continuous masking for an echolocating sperm whale facing a sonar was predicted for sonar sound pressure levels of 160 dB re 1 μPa2, with intermittent masking at levels of 120 dB re 1 μPa2, but model predictions strongly depended on the animal orientation, harmonic content of the sonar, click source level, and target strength of the prey. The masking model predicted lower masking potential of buzz clicks compared to regular clicks, even though the energy source level is much lower. For buzz clicks, the lower source level is compensated for by the reduced two-way propagation loss to nearby prey during buzzes. These results help to predict what types of behavioral changes could indicate masking in the wild. Several key knowledge gaps related to masking potential of sonar in echolocating odontocetes were identified that require further investigation to assess the significance of masking.
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Affiliation(s)
- A M von Benda-Beckmann
- Acoustics and Sonar, Netherlands Organization for Applied Scientific Research (TNO), P.O. Box 96864, The Hague 2509 JG, The Netherlands
| | - S Isojunno
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom
| | - M Zandvliet
- Acoustics and Sonar, Netherlands Organization for Applied Scientific Research (TNO), P.O. Box 96864, The Hague 2509 JG, The Netherlands
| | - M A Ainslie
- JASCO Applied Sciences (Deutschland) GmbH, Eschborn, Germany
| | - P J Wensveen
- Faculty of Life and Environmental Sciences, University of Iceland, Askja, Sturlugata 7, 102 Reykjavik, Iceland
| | - P L Tyack
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom
| | - P H Kvadsheim
- Sensor and Surveillance Systems, Norwegian Defense Research Establishment (FFI), NO-3191 Horten, Norway
| | - F P A Lam
- Acoustics and Sonar, Netherlands Organization for Applied Scientific Research (TNO), P.O. Box 96864, The Hague 2509 JG, The Netherlands
| | - P J O Miller
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom
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von Benda-Beckmann AM, Wensveen PJ, Prior M, Ainslie MA, Hansen RR, Isojunno S, Lam FPA, Kvadsheim PH, Miller PJO. Predicting acoustic dose associated with marine mammal behavioural responses to sound as detected with fixed acoustic recorders and satellite tags. J Acoust Soc Am 2019; 145:1401. [PMID: 31067938 DOI: 10.1121/1.5093543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 02/20/2019] [Indexed: 06/09/2023]
Abstract
To understand the consequences of underwater noise exposure for cetaceans, there is a need for assessments of behavioural responses over increased spatial and temporal scales. Bottom-moored acoustic recorders and satellite tags provide such long-term and large spatial coverage of behaviour compared to short-duration acoustic-recording tags. However, these tools result in a decreased resolution of data from which an animal response can be inferred, and no direct recording of the sound received at the animal. This study discusses the consequence of the decreased resolution of data from satellite tags and fixed acoustic recorders on the acoustic dose estimated by propagation modelling and presents a method for estimating the range of sound levels that animals observed with these methods have received. This problem is illustrated using experimental results obtained during controlled exposures of northern bottlenose whales (Hyperoodon ampullatus) exposed to naval sonar, carried out near Jan Mayen, Norway. It is shown that variability and uncertainties in the sound field, resulting from limited sampling of the acoustic environment, as well as decreased resolution in animal locations, can lead to quantifiable uncertainties in the estimated acoustic dose associated with the behavioural response (in this case avoidance and cessation of foraging).
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Affiliation(s)
- A M von Benda-Beckmann
- Netherlands Organisation for Applied Scientific Research (TNO), The Hague, The Netherlands
| | - P J Wensveen
- Sea Mammal Research Unit, School of Biology, Scottish Oceans Institute, University of St Andrews, St Andrews, United Kingdom
| | - M Prior
- Netherlands Organisation for Applied Scientific Research (TNO), The Hague, The Netherlands
| | - M A Ainslie
- Netherlands Organisation for Applied Scientific Research (TNO), The Hague, The Netherlands
| | - R R Hansen
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - S Isojunno
- Sea Mammal Research Unit, School of Biology, Scottish Oceans Institute, University of St Andrews, St Andrews, United Kingdom
| | - F P A Lam
- Netherlands Organisation for Applied Scientific Research (TNO), The Hague, The Netherlands
| | - P H Kvadsheim
- Norwegian Defence Research Establishment (FFI), Defence Systems, Horten, Norway
| | - P J O Miller
- Sea Mammal Research Unit, School of Biology, Scottish Oceans Institute, University of St Andrews, St Andrews, United Kingdom
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Curé C, Isojunno S, Visser F, Wensveen PJ, Sivle LD, Kvadsheim PH, Lam FPA, Miller PJO. Biological significance of sperm whale responses to sonar: comparison with anti-predator responses. ENDANGER SPECIES RES 2016. [DOI: 10.3354/esr00748] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Harris CM, Sadykova D, DeRuiter SL, Tyack PL, Miller PJO, Kvadsheim PH, Lam FPA, Thomas L. Dose response severity functions for acoustic disturbance in cetaceans using recurrent event survival analysis. Ecosphere 2015. [DOI: 10.1890/es15-00242.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Miller PJO, Kvadsheim PH, Lam FPA, Tyack PL, Curé C, DeRuiter SL, Kleivane L, Sivle LD, van IJsselmuide SP, Visser F, Wensveen PJ, von Benda-Beckmann AM, Martín López LM, Narazaki T, Hooker SK. First indications that northern bottlenose whales are sensitive to behavioural disturbance from anthropogenic noise. R Soc Open Sci 2015; 2:140484. [PMID: 26543576 PMCID: PMC4632540 DOI: 10.1098/rsos.140484] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 05/08/2015] [Indexed: 05/17/2023]
Abstract
Although northern bottlenose whales were the most heavily hunted beaked whale, we have little information about this species in its remote habitat of the North Atlantic Ocean. Underwater anthropogenic noise and disruption of their natural habitat may be major threats, given the sensitivity of other beaked whales to such noise disturbance. We attached dataloggers to 13 northern bottlenose whales and compared their natural sounds and movements to those of one individual exposed to escalating levels of 1-2 kHz upsweep naval sonar signals. At a received sound pressure level (SPL) of 98 dB re 1 μPa, the whale turned to approach the sound source, but at a received SPL of 107 dB re 1 μPa, the whale began moving in an unusually straight course and then made a near 180° turn away from the source, and performed the longest and deepest dive (94 min, 2339 m) recorded for this species. Animal movement parameters differed significantly from baseline for more than 7 h until the tag fell off 33-36 km away. No clicks were emitted during the response period, indicating cessation of normal echolocation-based foraging. A sharp decline in both acoustic and visual detections of conspecifics after exposure suggests other whales in the area responded similarly. Though more data are needed, our results indicate high sensitivity of this species to acoustic disturbance, with consequent risk from marine industrialization and naval activity.
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Affiliation(s)
- P. J. O. Miller
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
- Author for correspondence: P. J. O. Miller e-mail:
| | - P. H. Kvadsheim
- Maritime Systems Division, Norwegian Defence Research Establishment (FFI), Horten 3191, Norway
| | - F. P. A. Lam
- Acoustics and Sonar, Netherlands Organisation for Applied Scientific Research (TNO), PO Box 96864, 2509 JG The Hague, The Netherlands
| | - P. L. Tyack
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - C. Curé
- Acoustic Group, Centre for Expertise and Engineering on Risks, Urban and Country Planning, Environment and Mobility (CEREMA - DTer Est), F 67035 Strasbourg cedex2, France
| | - S. L. DeRuiter
- Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Fife KY16 9LZ, UK
| | - L. Kleivane
- Maritime Systems Division, Norwegian Defence Research Establishment (FFI), Horten 3191, Norway
| | - L. D. Sivle
- Institute of Marine Research (IMR), PO Box 1870 Nordnes, Bergen 5817, Norway
| | - S. P. van IJsselmuide
- Acoustics and Sonar, Netherlands Organisation for Applied Scientific Research (TNO), PO Box 96864, 2509 JG The Hague, The Netherlands
| | - F. Visser
- Kelp Marine Research, Loniusstraat 9, 1624 CJ Hoorn, The Netherlands
- Behavioural Biology Group, Leiden University, PO Box 9505, 2300 RA Leiden, The Netherlands
| | - P. J. Wensveen
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - A. M. von Benda-Beckmann
- Acoustics and Sonar, Netherlands Organisation for Applied Scientific Research (TNO), PO Box 96864, 2509 JG The Hague, The Netherlands
| | - L. M. Martín López
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - T. Narazaki
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - S. K. Hooker
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
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Antunes R, Kvadsheim PH, Lam FPA, Tyack PL, Thomas L, Wensveen PJ, Miller PJO. High thresholds for avoidance of sonar by free-ranging long-finned pilot whales (Globicephala melas). Mar Pollut Bull 2014; 83:165-80. [PMID: 24820645 DOI: 10.1016/j.marpolbul.2014.03.056] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/13/2014] [Accepted: 03/29/2014] [Indexed: 05/23/2023]
Abstract
The potential effects of exposing marine mammals to military sonar is a current concern. Dose-response relationships are useful for predicting potential environmental impacts of specific operations. To reveal behavioral response thresholds of exposure to sonar, we conducted 18 exposure/control approaches to 6 long-finned pilot whales. Source level and proximity of sonar transmitting one of two frequency bands (1-2 kHz and 6-7 kHz) were increased during exposure sessions. The 2-dimensional movement tracks were analyzed using a changepoint method to identify the avoidance response thresholds which were used to estimate dose-response relationships. No support for an effect of sonar frequency or previous exposures on the probability of response was found. Estimated response thresholds at which 50% of population show avoidance (SPLmax=170 dB re 1 μPa, SELcum=173 dB re 1 μPa(2) s) were higher than previously found for other cetaceans. The US Navy currently uses a generic dose-response relationship to predict the responses of cetaceans to naval active sonar, which has been found to underestimate behavioural impacts on killer whales and beaked whales. The navy curve appears to match more closely our results with long-finned pilot whales, though it might underestimate the probability of avoidance for pilot-whales at long distances from sonar sources.
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Affiliation(s)
- R Antunes
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK.
| | - P H Kvadsheim
- Norwegian Defence Research Establishment, Maritime Systems, N-3191 Horten, Norway
| | - F P A Lam
- Acoustics & Sonar Research Group, Netherlands Organization for Applied Scientific Research (TNO), Oude Waalsdorperweg 63, 2597 AK The Hague, The Netherlands
| | - P L Tyack
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK; Biology Department, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 94305, USA
| | - L Thomas
- CREEM Centre for Research into Ecological and Environmental Modelling, University of St. Andrews, St. Andrews, Scotland KY16 9LZ, UK
| | - P J Wensveen
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK
| | - P J O Miller
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Scotland KY16 8LB, UK
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Sivle LD, Kvadsheim PH, Fahlman A, Lam FPA, Tyack PL, Miller PJO. Changes in dive behavior during naval sonar exposure in killer whales, long-finned pilot whales, and sperm whales. Front Physiol 2012; 3:400. [PMID: 23087648 PMCID: PMC3468818 DOI: 10.3389/fphys.2012.00400] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 09/22/2012] [Indexed: 11/24/2022] Open
Abstract
Anthropogenic underwater sound in the environment might potentially affect the behavior of marine mammals enough to have an impact on their reproduction and survival. Diving behavior of four killer whales (Orcinus orca), seven long-finned pilot whales (Globicephala melas), and four sperm whales (Physeter macrocephalus) was studied during controlled exposures to naval sonar [low frequency active sonar (LFAS): 1-2 kHz and mid frequency active sonar (MFAS): 6-7 kHz] during three field seasons (2006-2009). Diving behavior was monitored before, during and after sonar exposure using an archival tag placed on the animal with suction cups. The tag recorded the animal's vertical movement, and additional data on horizontal movement and vocalizations were used to determine behavioral modes. Killer whales that were conducting deep dives at sonar onset changed abruptly to shallow diving (ShD) during LFAS, while killer whales conducting deep dives at the onset of MFAS did not alter dive mode. When in ShD mode at sonar onset, killer whales did not change their diving behavior. Pilot and sperm whales performed normal deep dives (NDD) during MFAS exposure. During LFAS exposures, long-finned pilot whales mostly performed fewer deep dives and some sperm whales performed shallower and shorter dives. Acoustic recording data presented previously indicates that deep diving (DD) is associated with feeding. Therefore, the observed changes in dive behavior of the three species could potentially reduce the foraging efficiency of the affected animals.
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Affiliation(s)
| | - P. H. Kvadsheim
- Norwegian Defence Research Establishment (FFI), Maritime Systems DivisionHorten, Norway
| | - A. Fahlman
- Woods Hole Oceanographic InstitutionWoods Hole, MA, USA
- Department of Life Sciences, Texas A&M Corpus ChristiTexas, TX, USA
| | - F. P. A. Lam
- Netherlands Organisation for Applied Scientific Research (TNO), Acoustics and Sonar Research GroupThe Hague, Netherlands
| | - P. L. Tyack
- Woods Hole Oceanographic InstitutionWoods Hole, MA, USA
- Sea Mammal Research Unit, University of St. AndrewsSt. Andrews, UK
| | - P. J. O. Miller
- Sea Mammal Research Unit, University of St. AndrewsSt. Andrews, UK
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Kvadsheim PH, Miller PJO, Tyack PL, Sivle LD, Lam FPA, Fahlman A. Estimated Tissue and Blood N(2) Levels and Risk of Decompression Sickness in Deep-, Intermediate-, and Shallow-Diving Toothed Whales during Exposure to Naval Sonar. Front Physiol 2012; 3:125. [PMID: 22590458 PMCID: PMC3349243 DOI: 10.3389/fphys.2012.00125] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/14/2012] [Indexed: 11/29/2022] Open
Abstract
Naval sonar has been accused of causing whale stranding by a mechanism which increases formation of tissue N2 gas bubbles. Increased tissue and blood N2 levels, and thereby increased risk of decompression sickness (DCS), is thought to result from changes in behavior or physiological responses during diving. Previous theoretical studies have used hypothetical sonar-induced changes in both behavior and physiology to model blood and tissue N2 tension PN2, but this is the first attempt to estimate the changes during actual behavioral responses to sonar. We used an existing mathematical model to estimate blood and tissue N2 tension PN2 from dive data recorded from sperm, killer, long-finned pilot, Blainville’s beaked, and Cuvier’s beaked whales before and during exposure to Low- (1–2 kHz) and Mid- (2–7 kHz) frequency active sonar. Our objectives were: (1) to determine if differences in dive behavior affects risk of bubble formation, and if (2) behavioral- or (3) physiological responses to sonar are plausible risk factors. Our results suggest that all species have natural high N2 levels, with deep diving generally resulting in higher end-dive PN2 as compared with shallow diving. Sonar exposure caused some changes in dive behavior in both killer whales, pilot whales and beaked whales, but this did not lead to any increased risk of DCS. However, in three of eight exposure session with sperm whales, the animal changed to shallower diving, and in all these cases this seem to result in an increased risk of DCS, although risk was still within the normal risk range of this species. When a hypothetical removal of the normal dive response (bradycardia and peripheral vasoconstriction), was added to the behavioral response during model simulations, this led to an increased variance in the estimated end-dive N2 levels, but no consistent change of risk. In conclusion, we cannot rule out the possibility that a combination of behavioral and physiological responses to sonar have the potential to alter the blood and tissue end-dive N2 tension to levels which could cause DCS and formation of in vivo bubbles, but the actually observed behavioral responses of cetaceans to sonar in our study, do not imply any significantly increased risk of DCS.
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Affiliation(s)
- P H Kvadsheim
- Maritime Systems Division, Norwegian Defence Research Establishment (FFI) Horten, Norway
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Hooker SK, Fahlman A, Moore MJ, de Soto NA, de Quirós YB, Brubakk AO, Costa DP, Costidis AM, Dennison S, Falke KJ, Fernandez A, Ferrigno M, Fitz-Clarke JR, Garner MM, Houser DS, Jepson PD, Ketten DR, Kvadsheim PH, Madsen PT, Pollock NW, Rotstein DS, Rowles TK, Simmons SE, Van Bonn W, Weathersby PK, Weise MJ, Williams TM, Tyack PL. Deadly diving? Physiological and behavioural management of decompression stress in diving mammals. Proc Biol Sci 2012; 279:1041-50. [PMID: 22189402 PMCID: PMC3267154 DOI: 10.1098/rspb.2011.2088] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 11/28/2011] [Indexed: 11/19/2022] Open
Abstract
Decompression sickness (DCS; 'the bends') is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N(2)) loading during dives. However, recent observations have shown that gas bubbles may form and tissue injury may occur in marine mammals under certain circumstances. Gas kinetic models based on measured time-depth profiles further suggest the potential occurrence of high blood and tissue N(2) tensions. We review evidence for gas-bubble incidence in marine mammal tissues and discuss the theory behind gas loading and bubble formation. We suggest that diving mammals vary their physiological responses according to multiple stressors, and that the perspective on marine mammal diving physiology should change from simply minimizing N(2) loading to management of the N(2) load. This suggests several avenues for further study, ranging from the effects of gas bubbles at molecular, cellular and organ function levels, to comparative studies relating the presence/absence of gas bubbles to diving behaviour. Technological advances in imaging and remote instrumentation are likely to advance this field in coming years.
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Affiliation(s)
- S K Hooker
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, Fife, UK.
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Abstract
Heat flux models have been used to predict metabolic rates of marine mammals, generally by estimating conductive heat transfer through their blubber layer. Recently, Kvadsheim et al. (1997) found that such models tend to overestimate metabolic rates, and that such errors probably result from the asymmetrical distribution of blubber. This problem may be avoided if reliable estimates of heat flux through the skin of the animals are obtained by using models that combine calculations of conductive heat flux through the skin and fur, and convective heat flux from the surface of the animal to the environment. We evaluated this approach based on simultaneous measurements of metabolic rates and of input parameters necessary for heat flux calculations, as obtained from four harp seals (Phoca groenlandica) resting in cold water. Heat flux estimates were made using two free convection models (double-flat-plate and cylindrical geometry) and one forced convection model (single-flat-plate geometry). We found that heat flux estimates generally underestimated metabolic rates, on average by 26-58%, and that small variations in input parameters caused large variations in these estimates. We conclude that cutaneous heat flux models are too inaccurate and sensitive to small errors in input parameters to provide reliable estimates of metabolic rates of marine mammals.
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Affiliation(s)
- P Boily
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA.
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Abstract
The trunk of marine mammals is encased in a blubber layer which provides thermal insulation that can be changed by circulatory adjustments. The extremities, on the other hand, are poorly insulated but have vascular arrangements constructed for prevention or promotion of heat loss depending on the thermal state of the animal. We have studied the importance of different body parts as sites for heat dissipation and also assessed the effect of circulatory adjustments on heat transfer through blubber, by combining direct measurements of heat flux from the flippers and trunk with simultaneous recordings of temperature gradients through the blubber and metabolic rates of harp seals (Phoca groenlandica) subjected to water temperatures between 1 and 24 degrees C. We also determined the thermal conductivity of blubber samples from the same animals after death, and compared this with the insulative properties of live blubber. At the lowest water temperatures, the insulative properties of live blubber were similar to those of dead blubber, and heat loss from the flippers only accounted for 2-6% of the metabolic heat production. As heat load increased with increasing water temperatures, the fraction of heat lost from the flippers increased, to 19-48% at 24 degrees C, while the fraction lost from the trunk decreased, despite an increase in the convective (circulatory) heat transfer through the blubber layer.
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Affiliation(s)
- P H Kvadsheim
- Department of Arctic Biology, University of Tromsø, Norway
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