The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Nikoletta Diogou - One of the best experts on this subject based on the ideXlab platform.
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Sperm Whale physeter macrocephalus acoustic ecology at ocean station papa in the gulf of alaska part 1 detectability and seasonality
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Sharon L Nieukirk, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Sperm Whales Physeter macrocephalus produce loud, stereotypical click sequences and are an ideal species to be studied with passive acoustic techniques. To increase our limited knowledge of Sperm Whale occurrence patterns in remote and inaccessible locations of the North Pacific, we analyzed a five-year-long (June 2007–April 2012) acoustic data set recorded at Ocean Station PAPA (OSP; 50°N, 145°W) in the Gulf of Alaska (GOA). Firstly, we assessed the Sperm Whale detection performance of the Passive Aquatic Listener (PAL), and secondly, we investigated temporal patterns of Sperm Whale presence at OSP. The PAL proved highly efficient, with above 50% probability of detecting more than two Sperm Whales, a condition met for over 50% of the recordings. Results indicated that Sperm Whale clicks were recorded year-round, with a clear seasonal pattern. The number of detections during the summer months was approximately 70% higher compared to winter. An ambient noise analysis showed that differences in detection rates were likely not driven by seasonal changes in ambient noise levels. The average propagation range of Sperm Whale clicks ranged between 7 and 8 km between summer and winter, with slightly decreased detection distances observed in winter. Seasonal shifts in the intensity of the Alaska Current and the latitudinal oscillations of the North Pacific Transition Zone results in changes in water mixing, transport of nutrients and the concentration of prey such as squid, which likely drives Sperm Whale distribution.
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Sperm Whale physeter macrocephalus acoustic ecology at ocean station papa in the gulf of alaska part 2 oceanographic drivers of interannual variability
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Understanding top predator responses to environmental variability is key to assessing potential impacts of global warming on marine ecosystems. However, tracking environmental changes and their effects across multiple trophic levels up to predators can be difficult. Here, we related the interannual (2007–2012) acoustic occurrence of Sperm Whales (Physeter macrocephalus) at Ocean Station PAPA (OSP), in the offshore Gulf of Alaska (GOA), to environmental drivers within an explicit time-series modeling framework. In a model based on a combination of in-situ and remotely sensed variables, ocean heat content (HC), meridional current (V), eddy kinetic energy (EKE), strength of the permanent pycnocline (maxBVF), sea surface temperature (SST) and SST standard deviation (SSTsd) explained 51% of the variability in Sperm Whale presence, indicating a positive relationship between Sperm Whale occurrence and increased ocean heating, vertical stratification, and circulation. Sperm Whale detections were anomalously high in summer 2010 and winter 2011, and anomalously low at the end of summer and winter 2008, and spring 2011. Results suggest these strongly anomalous detection events reflect a response to El Nino–Southern Oscillation (ENSO) events, with an 8-month lag. In the study area, El Nino leads to a stronger permanent pycnocline, a weakening of the Alaska Gyre, a northward expansion of the North Pacific Subarctic Frontal Zone, and a prevalence of offshore mesoscale eddies, likely favoring the abundance of squid and their predator, the Sperm Whale. The overall results are consistent with a scenario of increasing Sperm Whale occurrence at high latitudes under increased ocean warming.
Holger Klinck - One of the best experts on this subject based on the ideXlab platform.
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Sperm Whale physeter macrocephalus acoustic ecology at ocean station papa in the gulf of alaska part 1 detectability and seasonality
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Sharon L Nieukirk, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Sperm Whales Physeter macrocephalus produce loud, stereotypical click sequences and are an ideal species to be studied with passive acoustic techniques. To increase our limited knowledge of Sperm Whale occurrence patterns in remote and inaccessible locations of the North Pacific, we analyzed a five-year-long (June 2007–April 2012) acoustic data set recorded at Ocean Station PAPA (OSP; 50°N, 145°W) in the Gulf of Alaska (GOA). Firstly, we assessed the Sperm Whale detection performance of the Passive Aquatic Listener (PAL), and secondly, we investigated temporal patterns of Sperm Whale presence at OSP. The PAL proved highly efficient, with above 50% probability of detecting more than two Sperm Whales, a condition met for over 50% of the recordings. Results indicated that Sperm Whale clicks were recorded year-round, with a clear seasonal pattern. The number of detections during the summer months was approximately 70% higher compared to winter. An ambient noise analysis showed that differences in detection rates were likely not driven by seasonal changes in ambient noise levels. The average propagation range of Sperm Whale clicks ranged between 7 and 8 km between summer and winter, with slightly decreased detection distances observed in winter. Seasonal shifts in the intensity of the Alaska Current and the latitudinal oscillations of the North Pacific Transition Zone results in changes in water mixing, transport of nutrients and the concentration of prey such as squid, which likely drives Sperm Whale distribution.
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Sperm Whale physeter macrocephalus acoustic ecology at ocean station papa in the gulf of alaska part 2 oceanographic drivers of interannual variability
Deep Sea Research Part I: Oceanographic Research Papers, 2019Co-Authors: Nikoletta Diogou, Daniel M Palacios, Jeffrey A Nystuen, Evangelos Papathanassiou, Stelios Katsanevakis, Holger KlinckAbstract:Abstract Understanding top predator responses to environmental variability is key to assessing potential impacts of global warming on marine ecosystems. However, tracking environmental changes and their effects across multiple trophic levels up to predators can be difficult. Here, we related the interannual (2007–2012) acoustic occurrence of Sperm Whales (Physeter macrocephalus) at Ocean Station PAPA (OSP), in the offshore Gulf of Alaska (GOA), to environmental drivers within an explicit time-series modeling framework. In a model based on a combination of in-situ and remotely sensed variables, ocean heat content (HC), meridional current (V), eddy kinetic energy (EKE), strength of the permanent pycnocline (maxBVF), sea surface temperature (SST) and SST standard deviation (SSTsd) explained 51% of the variability in Sperm Whale presence, indicating a positive relationship between Sperm Whale occurrence and increased ocean heating, vertical stratification, and circulation. Sperm Whale detections were anomalously high in summer 2010 and winter 2011, and anomalously low at the end of summer and winter 2008, and spring 2011. Results suggest these strongly anomalous detection events reflect a response to El Nino–Southern Oscillation (ENSO) events, with an 8-month lag. In the study area, El Nino leads to a stronger permanent pycnocline, a weakening of the Alaska Gyre, a northward expansion of the North Pacific Subarctic Frontal Zone, and a prevalence of offshore mesoscale eddies, likely favoring the abundance of squid and their predator, the Sperm Whale. The overall results are consistent with a scenario of increasing Sperm Whale occurrence at high latitudes under increased ocean warming.
Hal Whitehead - One of the best experts on this subject based on the ideXlab platform.
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critical decline of the eastern caribbean Sperm Whale population
PLOS ONE, 2016Co-Authors: Shane Gero, Hal WhiteheadAbstract:Sperm Whale (Physeter macrocephalus) populations were expected to rebuild following the end of commercial whaling. We document the decline of the population in the eastern Caribbean by tracing demographic changes of well-studied social units. We address hypotheses that, over a ten-year period of dedicated effort (2005–2015), unit size, numbers of calves and/or calving rates have each declined. Across 16 units, the number of adults decreased in 12 units, increased in two, and showed no change in two. The number of adults per unit decreased at -0.195 individuals/yr (95% CI: -0.080 to -0.310; P = 0.001). The number of calves also declined, but the decline was not significant. This negative trend of -4.5% per year in unit size started in about 2010, with numbers being fairly stable until then. There are several natural and anthropogenic threats, but no well-substantiated cause for the decline.
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Sperm Whale physeter macrocephalus
Encyclopedia of Marine Mammals (Second Edition), 2009Co-Authors: Hal WhiteheadAbstract:Publisher Summary Sperm Whales are animals of extremes. They have unusually large body sizes, sexual dimorphism, brain sizes, home ranges, dive depths, and dive times; they have an ecological role that may be unrivaled in the ocean; and their vocalizations, social structure, and historical relationship with humans are all remarkable. With the exception of humans and killer Whales, few animals on earth are as widely distributed as the Sperm Whale. They can be seen near the ice-edge in both hemispheres and are also common along the Equator, especially in the Pacific. As with so many aspects of Sperm Whale biology, the sexes have very different distributions. Concentrations of a few hundred to a few thousand Sperm Whales can be found in areas a few hundred kilometers across characterized by a relatively high deep water biomass and usually situated within ground. The Sperm Whale has a most catholic diet consisting of many of the larger organisms that inhabit the deeper regions of the oceans. Females appear to principally eat squid weighing between 0.1 and 10 kg. Males use the same squid taxa as females but tend to eat larger individuals. The Sperm Whale is the epitome of the “K-selected” mammal, one presumed to have evolved in an environment of competition for resources with members of its own species. It has a very low birth rate, slow growth, slow maturation, and high survival. The Sperm Whale has survived the onslaught of the Whalers better than most other large Whales. There are still a few hundred thousand Sperm Whales left in the ocean, Sperm Whale food is of little interest to human fishers, and their deepwater home is farther from most sources of pollution than the preferred habitat of most other marine mammals. However, the effects of whaling seem to be lingering. In the southeast Pacific, where modern whaling on males was particularly severe, large breeding males are still scarce and calving seems depressed below the replacement rate. In other parts of the world, the picture appears brighter.
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SUCKLING BEHAVIOR IN Sperm Whale CALVES: OBSERVATIONS AND HYPOTHESES
Marine Mammal Science, 2007Co-Authors: Shane Gero, Hal WhiteheadAbstract:This study is the first to describe quantitatively the apparent suckling behavior of Sperm Whale, Physeter macrocephalus (Linnaeus, 1758), calves using observations from both above and below the surface. Peduncle dives are short (mean 14 s) dives made by Sperm Whale calves beside the peduncle of an adult female, which were previously assumed to be indicative of suckling. Photo-identification and focal calf-follows were used to collect data during 177 peduncle dive bouts from 22 different calves (11 calves from the Caribbean Sea, 11 from the Sargasso Sea), one of which was followed on forty different days. We found that peduncle diving in Sperm Whale calves is laterally asymmetrical with a bias to the left side of the escorting adult (69.8% of peduncle dives) and that calves generally do not switch sides during a bout of peduncle dives (switches occurred in only 10.8% of bouts). Further subsurface observations gave insight into potential alternative functions of peduncle diving. These alternative hypotheses, including nasal suckling, and the existing supporting evidence for each are discussed. It is likely that peduncle diving is related to suckling but that the exact function of the dives and manner in which Sperm Whale calves ingest milk remains unclear.
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Sperm Whale feeding variation by location year social group and clan evidence from stable isotopes
Marine Ecology Progress Series, 2007Co-Authors: Marianne Marcoux, Hal Whitehead, Luke RendellAbstract:We studied the diet of Sperm Whales Physeter macrocephalus by measuring carbon and nitrogen isotope ratios in 106 sloughed skin samples and 10 squid beaks (Histioteuthidae spp.), the latter collected from Sperm Whale defecations. Samples were collected during 8 studies conducted between 1989 and 2000 in the South Pacific Ocean. We examined diet variation across region, year, social group and vocal clan. The isotopic signatures of groups and acoustic clans of Sperm Whales were compared using a nested analysis of variance (ANOVA) and the absolute distances between each pair of samples were calculated. The δ 13 C and δ 15 N values ranged from -17.8 to -14.5‰ and from 8.5 to 22.3‰, respectively. The δ 15 N values of defecated squids were about 3‰ lower than val- ues of the Sperm Whale, corresponding to a trophic difference of one level. There was a significant difference in both the δ 15 N and δ 13 C values between groups (nested within clans and the studies) and clans (nested within studies). Most of the variation was between studies. The latitude at which the samples were collected was inversely related to the δ 15 N values. We suggest that the differences in diet between the groups from different clans are mainly caused by characteristic behaviour of the clans and differential use of micro-habitats; i.e. groups from a clan with a generally more benthic or inshore distribution had higher δ 13 C than groups with a more offshore or pelagic influence, a general characteristic of this isotope in marine habitats.
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coherence between 19th century Sperm Whale distributions and satellite derived pigments in the tropical pacific
Marine Ecology Progress Series, 1996Co-Authors: Nathalie Jaquet, Hal Whitehead, Marlon R LewisAbstract:It has often been suggested that, given their large food requirements, Sperm Whale Physeter macrocephalus distributions should reflect the distribution of productive ocean environments, and it seems therefore that chlorophyll concentration might be a good indicator of Sperm Whale distribution. To examine the existence of such a relationship, and to determine over which scales it occurs, Sperm Whale density was correlated with phytoplankton pigment concentration over a range of spatial and temporal scales. Sperm Whale distribution was determined using records of kills from 19th century Yankee whaling, and the distribution of pigment concentration from satellite colour observations averaged over an 8 yr interval. These measures were coniparecl over scales of 220 k m square to 1780 km square. The distribution of Sperm Whales in the temperate and tropical Pacific Ocean was associated with distributions of phytoplankton pigment over every spatial scale considered, and the coefficient of correlation increased with increasing spatial scale. However, a few exceptions to this scheme were found, implying that other factors could be of importance in some regions. This study confirmed the existence of a space lag and a time lag between a peak in chlorophyll concentration and a peak in Sperm Whale density. It also demonstrated that over large spatial scales, and when the data are averaged over large temporal scales, chlorophyll concentration is a good indicator of Sperm Whale distribution, and that over these scales ocean colour recorded from space could help predict areas of high or low Sperm Whale density.
Willy Dabin - One of the best experts on this subject based on the ideXlab platform.
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beached bachelors an extensive study on the largest recorded Sperm Whale physeter macrocephalus mortality event in the north sea
PLOS ONE, 2018Co-Authors: Lonneke L Ijsseldijk, Abbo Van Neer, Rob Deaville, Lineke Begeman, Marco W G Van De Bildt, Judith M A Van Den Brand, Andrew Brownlow, Richard Czeck, Willy DabinAbstract:Between the 8th January and the 25th February 2016, the largest Sperm Whale Physeter macrocephalus mortality event ever recorded in the North Sea occurred with 30 Sperm Whales stranding in five countries within six weeks. All Sperm Whales were immature males. Groups were stratified by size, with the smaller animals stranding in the Netherlands, and the largest in England. The majority (n = 27) of the stranded animals were necropsied and/or sampled, allowing for an international and comprehensive investigation into this mortality event. The animals were in fair to good nutritional condition and, aside from the pathologies caused by stranding, did not exhibit significant evidence of disease or trauma. Infectious agents were found, including various parasite species, several bacterial and fungal pathogens and a novel alphaherpesvirus. In nine of the Sperm Whales a variety of marine litter was found. However, none of these findings were considered to have been the primary cause of the stranding event. Potential anthropogenic and environmental factors that may have caused the Sperm Whales to enter the North Sea were assessed. Once Sperm Whales enter the North Sea and head south, the water becomes progressively shallower (<40 m), making this region a global hotspot for Sperm Whale strandings. We conclude that the reasons for Sperm Whales to enter the southern North Sea are the result of complex interactions of extrinsic environmental factors. As such, these large mortality events seldom have a single ultimate cause and it is only through multidisciplinary, collaborative approaches that potentially multifactorial large-scale stranding events can be effectively investigated.
Luke Rendell - One of the best experts on this subject based on the ideXlab platform.
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modelling Sperm Whale habitat preference a novel approach combining transect and follow data
Marine Ecology Progress Series, 2011Co-Authors: Enrico Pirotta, Monique Mackenzie, Jason Matthiopoulos, Lindesay A S Scotthayward, Luke RendellAbstract:ABSTRACT: Sperm Whale Physeter macrocephalus habitat preferences are still poorly understood inthe Mediterranean, despite the population being classified as ‘Endangered’ by the IUCN. Techniquesto make the best use of multiple data sources are important in improving this situation. This work pro-vides a detailed evaluation of Sperm Whale distribution and habitat use around the Balearic Islandsusing a novel analytical framework that combines transect and follow data while accounting for anyautocorrelation present. During dedicated research cruises (2003 to 2008), Sperm Whales werelocated by listening at regular intervals along a search track and subsequently followed acoustically.Sperm Whales were encountered 56 times and followed for periods ranging from a few hours to 3 d.Logistic Generalized Additive Models were used to model the probability of Whale presence acrossthe study area as a function of environmental variables, and Generalized Estimating Equations wereused to account for autocorrelation. The results suggest that Sperm Whales do not use the region uni-formly and that topography plays a key role in shaping their distribution. Moreover, solitary individ-uals were found to use the habitat differently from groups. This segregation appeared to be driven bywater temperature and might reflect different needs or intraspecific competition. By shedding lighton Sperm Whale habitat preference in such a critical area, this study represents an important steptowards the implementation of conservation measures for this population.KEY WORDS: Habitat modelling · Cetacean · Distribution · Balearic Islands · GAM · GEE · Multi-scale
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Modelling Sperm Whale habitat preference: A novel approach combining transect and follow data
Marine Ecology Progress Series, 2011Co-Authors: Enrico Pirotta, Lindesay Scott-hayward, Monique Mackenzie, Jason Matthiopoulos, Luke RendellAbstract:Sperm Whale Physeter macrocephalus habitat preferences are still poorly understood in the Mediterranean, despite the population being classified as ‘Endangered’ by the IUCN. Techniques to make the best use of multiple data sources are important in improving this situation. This work pro- vides a detailed evaluation of Sperm Whale distribution and habitat use around the Balearic Islands using a novel analytical framework that combines transect and follow data while accounting for any autocorrelation present. During dedicated research cruises (2003 to 2008), Sperm Whales were located by listening at regular intervals along a search track and subsequently followed acoustically. Sperm Whales were encountered 56 times and followed for periods ranging from a few hours to 3 d. Logistic Generalized Additive Models were used to model the probability of Whale presence across the study area as a function of environmental variables, and Generalized Estimating Equations were used to account for autocorrelation. The results suggest that Sperm Whales do not use the region uni- formly and that topography plays a key role in shaping their distribution. Moreover, solitary individ- uals were found to use the habitat differently from groups. This segregation appeared to be driven by water temperature and might reflect different needs or intraspecific competition. By shedding light on Sperm Whale habitat preference in such a critical area, this study represents an important step towards the implementation of conservation measures for this population.
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Sperm Whale feeding variation by location year social group and clan evidence from stable isotopes
Marine Ecology Progress Series, 2007Co-Authors: Marianne Marcoux, Hal Whitehead, Luke RendellAbstract:We studied the diet of Sperm Whales Physeter macrocephalus by measuring carbon and nitrogen isotope ratios in 106 sloughed skin samples and 10 squid beaks (Histioteuthidae spp.), the latter collected from Sperm Whale defecations. Samples were collected during 8 studies conducted between 1989 and 2000 in the South Pacific Ocean. We examined diet variation across region, year, social group and vocal clan. The isotopic signatures of groups and acoustic clans of Sperm Whales were compared using a nested analysis of variance (ANOVA) and the absolute distances between each pair of samples were calculated. The δ 13 C and δ 15 N values ranged from -17.8 to -14.5‰ and from 8.5 to 22.3‰, respectively. The δ 15 N values of defecated squids were about 3‰ lower than val- ues of the Sperm Whale, corresponding to a trophic difference of one level. There was a significant difference in both the δ 15 N and δ 13 C values between groups (nested within clans and the studies) and clans (nested within studies). Most of the variation was between studies. The latitude at which the samples were collected was inversely related to the δ 15 N values. We suggest that the differences in diet between the groups from different clans are mainly caused by characteristic behaviour of the clans and differential use of micro-habitats; i.e. groups from a clan with a generally more benthic or inshore distribution had higher δ 13 C than groups with a more offshore or pelagic influence, a general characteristic of this isotope in marine habitats.
