One of the most important challenges researchers and managers confront in conservation ecology is... more One of the most important challenges researchers and managers confront in conservation ecology is predicting a population’s response to sub-lethal stressors. Such predictions have been particularly elusive when assessing responses of large marine mammals to past anthropogenic pressures. Recently developed techniques involving baleen whale earplugs combine age estimates with cortisol measurements to assess spatial and temporal stress/stressor relationships. Here we show a relationship between baseline-corrected cortisol levels and corresponding whaling counts of fin, humpback, and blue whales in the Northern Hemisphere spanning the 20th century. We also model the impact of alternative demographic and environmental factors and determine that increased anomalies of sea surface temperature over a 46-year mean (1970–2016) were positively associated with cortisol levels. While industrial whaling can deplete populations by direct harvest, our data underscore a widespread stress response in...
Extinctions and declines of large marine vertebrates have major ecological impacts and are of cri... more Extinctions and declines of large marine vertebrates have major ecological impacts and are of critical concern in marine environments. The Caribbean monk seal, Monachus tropicalis, last definitively reported in 1952, was one of the few marine mammal species to become extinct in historical times. Despite its importance for understanding the evolutionary biogeography of southern phocids, the relationships of
The Hawaiian monk seal (Monachus schauinslandi) is an endangered species only found within the Ha... more The Hawaiian monk seal (Monachus schauinslandi) is an endangered species only found within the Hawaiian Archipelago. The majority of the breeding population for this seal is located around six islands in the Northwest Hawaiian Island chain (NWHI). Overall, both juvenile and adult seals have a wide range in 13C and 15N from 1912-2006 (13C: -12.5‰; 15N: 12.6‰). Seals in the northern NWHI were enriched in 13C by nearly 2‰ and depleted in 15N by nearly 6‰ during the 96 years. Meanwhile, seals within the middle and southern extent of the NWHI showed little to very slight decreases in 13C and 15N. Preliminary comparison of modern monk seals with selected potential prey in the southern NWHI indicate possible trophic reliance on a mix of reef fish, eels, and lobster. Commercial fishery data post-WWII indicate an overlap between fisheries and monk seal diets in lobster, squirrelfish, and goatfish. -22 -20 -18 -16 -14 -12 -10 -8 -6 3 6 9 12 1 3 C ( 0 / 0 0 ) 15N (/00) Adult Monk Se...
Baleen has been harvested by indigenous people for thousands of years, as well as collected by wh... more Baleen has been harvested by indigenous people for thousands of years, as well as collected by whalers as an additional product of commercial whaling in modern times. Baleen refers to the food-filtering system of Mysticeti whales; a full baleen rack consists of dozens of plates of a tough and flexible keratinous material that terminate in bristles. Due to its properties, baleen was a valuable raw material used in a wide range of artefacts, from implements to clothing. Baleen is not widely used today, however, analyses of this biomolecular tissue have the potential to contribute to conservation efforts, studies of genetic diversity and a better understanding of the exploitation and use of Mysticeti whales in past and recent times. Fortunately, baleen is present in abundance in museum natural history collections. However, it is often difficult or impossible to make a species identification of manufactured or old baleen. Here, we propose a new tool for biomolecular identification of ba...
Smithsonian at the poles : contributions to International Polar Year science, 2009
Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditiona... more Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditional knowledge to render a more complete description of tooth-related structures and to propose a new hypothesis for tusk function in the adult male. Gross anatomy fi ndings from computed tomography (CT) and magnetic resonance (MR) imaging and dissections of an adult male and female and one fetus, four to six months in development, were documented. Computed tomography scans rendered images of the tusks and vestigial teeth and their shared sources of innervation at the base of the tusks. Paired and asymmetrical tusks and vestigial teeth were observed in all three samples, and their relative positions reversed during development. Vestigial teeth shifted anteriorly during growth, and the developing tusks moved posteriorly as they developed. Examination of tusk microanatomy revealed the presence of a dentinal tubule network with lumena approximately 2 micrometers in diameter and 10-20 micrometers apart over the pulpal and erupted tusk surfaces. Orifi ces were present on the cementum surface indicating direct communication and sensory capability from the environment to the inner pulpal wall. Flexural strength of 95 MPa at mid tusk and 165 MPa at the base indicated resistance to high fl exural stresses. Inuit knowledge describes a tusk with remarkable and combined strength and fl exibility. Elder observations of anatomy are described by variable phenotypes and classifi ed by skin coloration, sex, and tusk expression. Behavioral observations of males leading seasonal migration groups, nonaggressive tusk encounters, and frequent sightings of smaller groups separated by sex add to the discussion of tusk function.
This study's objective was to investigate mandibular fractures in 50 short-finned pilot whales, G... more This study's objective was to investigate mandibular fractures in 50 short-finned pilot whales, Globicephala macrorhynchus, from two mass strandings. Based on current 1
The 6I3C and W N compositions of teeth used in combination with existing data provide dietary inf... more The 6I3C and W N compositions of teeth used in combination with existing data provide dietary information for different populations of western North Atlantic bottlenose dolphins (Ttlrsiops truncutus). The dental isotopic signatures of bottlenose dolphins collected during the 1980s significantly differ for coastal and offshore ecotypes and are consistent with reports that coastal forms feed primarily on fish whereas offshore individuals consume more squid. In a second study, the isotopic compositions of teeth from bottlenose dolphins that span a 100-yr period and data from published stomach content analyses as well as field observations made during the past 100 yr provide evidence that coastal bottlenose dolphins from the 1880s, 1920s, and 1980s had similar diets.
ABSTRACT Little is known about the ontogeny of brain size in pinnipeds despite potential function... more ABSTRACT Little is known about the ontogeny of brain size in pinnipeds despite potential functional implications of brain substrate (glucose, oxygen) requirements for diving, fasting, growth, and lactation strategies. We measured brain mass (brM) and cranial capacity (CC) in newborn and adult Weddell seals. Neonatal Weddell seals had brM that represented ~70% of adult brM. Weddell seals have the largest neonatal brain, proportional to adult brain, reported for any mammal to date, which is remarkable considering the relatively small size of Weddell seal pups at birth (6%–7% of maternal body mass) compared to neonates of other highly precocial mammals. Provision of sufficient glucose to maintain the large, well-developed brain of the neonatal Weddell seal has a nontrivial metabolic cost to both pup and mother. We therefore hypothesize that this phenomenon must have functional significance, such as allowing pups to acquire complex under-ice navigation skills during the period of maternal attendance.
North Atlantic harbour porpoises Phocoena phocoena (L.) face considerable energetic challenges, a... more North Atlantic harbour porpoises Phocoena phocoena (L.) face considerable energetic challenges, as they are relatively small marine mammals with an intense reproductive schedule and a cold-water habitat. Postnatal growth of these porpoises was described using ontogenetic allometry and body composition techniques. The cross-sectional sample contained robust calves, immature, and mature porpoises (n = 122) incidentally killed in commercial ®shing operations between 1992 and 1998. Total mass and the mass of 26 body components were measured using a standard dissection protocol. Most body components grew similarly in female and male porpoises. Blubber, brain and skull were negatively allometric, while muscle and reproductive tissues exhibited positive allometry. Female heart, liver, intestine and mesenteric lymph node grew at signi®cantly higher rates than in males. Male locomotor muscle and pelvic bones grew signi®cantly faster than in females. High growth rates for visceral and reproductive organs in porpoises, relative to other mammals, may underlie their early maturation and support their intensive, annual reproductive schedule. Relative to other cetaceans, porpoises seem to allocate a larger percentage of their total body mass to blubber. This allocation to blubber, which is greatest in calves (37% of body mass), may provide harbour porpoises with the thermal insulation required to live in cold water. The factors in¯uencing growth rates and differential investments in body composition seem to change at various stages of a porpoise's life. Energy allocation in porpoises seems to shift from an emphasis on developing an insulative blubber layer in young animals to preparing the body for annual reproduction at sexual maturity.
Bottlenose dolphins (Tursiops truncatus) collected during the 1987/88 mass mortality event along ... more Bottlenose dolphins (Tursiops truncatus) collected during the 1987/88 mass mortality event along the Atlantic coast of the United States have been analyzed for anthropogenic chemical contaminants. Average contaminant concentrations in adult males were higher than the average concentrations measured in adult females. Females could be divided into two groups by contaminant concentrations, one with low concentrations, and another with concentrations 4.4 times (PCBs) to 8.9 times (p,p'-DDE) greater. Contaminant concentrations in bottlenose were generally greater than the concentrations measured in either common (Delphinus delDhis) or white-sided (Lagenorhynchus acutus) dolphins from the western North Atlantic Ocean. A subset of animals screened for unusual chemical contaminants showed that numerous polybrominated chemicals were present, including polybrominated biphenyls and diphenyl ethers not previously found in marine mammals from U.S. coastal waters.
Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditiona... more Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditional knowledge to render a more complete description of tooth-related structures and to propose a new hypothesis for tusk function in the adult male. Gross anatomy fi ndings from computed tomography (CT) and magnetic resonance (MR) imaging and dissections of an adult male and female and one fetus, four to six months in development, were documented. Computed tomography scans rendered images of the tusks and vestigial teeth and their shared sources of innervation at the base of the tusks. Paired and asymmetrical tusks and vestigial teeth were observed in all three samples, and their relative positions reversed during development. Vestigial teeth shifted anteriorly during growth, and the developing tusks moved posteriorly as they developed. Examination of tusk microanatomy revealed the presence of a dentinal tubule network with lumena approximately 2 micrometers in diameter and 10-20 micrometers apart over the pulpal and erupted tusk surfaces. Orifi ces were present on the cementum surface indicating direct communication and sensory capability from the environment to the inner pulpal wall. Flexural strength of 95 MPa at mid tusk and 165 MPa at the base indicated resistance to high fl exural stresses. Inuit knowledge describes a tusk with remarkable and combined strength and fl exibility. Elder observations of anatomy are described by variable phenotypes and classifi ed by skin coloration, sex, and tusk expression. Behavioral observations of males leading seasonal migration groups, nonaggressive tusk encounters, and frequent sightings of smaller groups separated by sex add to the discussion of tusk function.
One of the most important challenges researchers and managers confront in conservation ecology is... more One of the most important challenges researchers and managers confront in conservation ecology is predicting a population’s response to sub-lethal stressors. Such predictions have been particularly elusive when assessing responses of large marine mammals to past anthropogenic pressures. Recently developed techniques involving baleen whale earplugs combine age estimates with cortisol measurements to assess spatial and temporal stress/stressor relationships. Here we show a relationship between baseline-corrected cortisol levels and corresponding whaling counts of fin, humpback, and blue whales in the Northern Hemisphere spanning the 20th century. We also model the impact of alternative demographic and environmental factors and determine that increased anomalies of sea surface temperature over a 46-year mean (1970–2016) were positively associated with cortisol levels. While industrial whaling can deplete populations by direct harvest, our data underscore a widespread stress response in...
Extinctions and declines of large marine vertebrates have major ecological impacts and are of cri... more Extinctions and declines of large marine vertebrates have major ecological impacts and are of critical concern in marine environments. The Caribbean monk seal, Monachus tropicalis, last definitively reported in 1952, was one of the few marine mammal species to become extinct in historical times. Despite its importance for understanding the evolutionary biogeography of southern phocids, the relationships of
The Hawaiian monk seal (Monachus schauinslandi) is an endangered species only found within the Ha... more The Hawaiian monk seal (Monachus schauinslandi) is an endangered species only found within the Hawaiian Archipelago. The majority of the breeding population for this seal is located around six islands in the Northwest Hawaiian Island chain (NWHI). Overall, both juvenile and adult seals have a wide range in 13C and 15N from 1912-2006 (13C: -12.5‰; 15N: 12.6‰). Seals in the northern NWHI were enriched in 13C by nearly 2‰ and depleted in 15N by nearly 6‰ during the 96 years. Meanwhile, seals within the middle and southern extent of the NWHI showed little to very slight decreases in 13C and 15N. Preliminary comparison of modern monk seals with selected potential prey in the southern NWHI indicate possible trophic reliance on a mix of reef fish, eels, and lobster. Commercial fishery data post-WWII indicate an overlap between fisheries and monk seal diets in lobster, squirrelfish, and goatfish. -22 -20 -18 -16 -14 -12 -10 -8 -6 3 6 9 12 1 3 C ( 0 / 0 0 ) 15N (/00) Adult Monk Se...
Baleen has been harvested by indigenous people for thousands of years, as well as collected by wh... more Baleen has been harvested by indigenous people for thousands of years, as well as collected by whalers as an additional product of commercial whaling in modern times. Baleen refers to the food-filtering system of Mysticeti whales; a full baleen rack consists of dozens of plates of a tough and flexible keratinous material that terminate in bristles. Due to its properties, baleen was a valuable raw material used in a wide range of artefacts, from implements to clothing. Baleen is not widely used today, however, analyses of this biomolecular tissue have the potential to contribute to conservation efforts, studies of genetic diversity and a better understanding of the exploitation and use of Mysticeti whales in past and recent times. Fortunately, baleen is present in abundance in museum natural history collections. However, it is often difficult or impossible to make a species identification of manufactured or old baleen. Here, we propose a new tool for biomolecular identification of ba...
Smithsonian at the poles : contributions to International Polar Year science, 2009
Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditiona... more Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditional knowledge to render a more complete description of tooth-related structures and to propose a new hypothesis for tusk function in the adult male. Gross anatomy fi ndings from computed tomography (CT) and magnetic resonance (MR) imaging and dissections of an adult male and female and one fetus, four to six months in development, were documented. Computed tomography scans rendered images of the tusks and vestigial teeth and their shared sources of innervation at the base of the tusks. Paired and asymmetrical tusks and vestigial teeth were observed in all three samples, and their relative positions reversed during development. Vestigial teeth shifted anteriorly during growth, and the developing tusks moved posteriorly as they developed. Examination of tusk microanatomy revealed the presence of a dentinal tubule network with lumena approximately 2 micrometers in diameter and 10-20 micrometers apart over the pulpal and erupted tusk surfaces. Orifi ces were present on the cementum surface indicating direct communication and sensory capability from the environment to the inner pulpal wall. Flexural strength of 95 MPa at mid tusk and 165 MPa at the base indicated resistance to high fl exural stresses. Inuit knowledge describes a tusk with remarkable and combined strength and fl exibility. Elder observations of anatomy are described by variable phenotypes and classifi ed by skin coloration, sex, and tusk expression. Behavioral observations of males leading seasonal migration groups, nonaggressive tusk encounters, and frequent sightings of smaller groups separated by sex add to the discussion of tusk function.
This study's objective was to investigate mandibular fractures in 50 short-finned pilot whales, G... more This study's objective was to investigate mandibular fractures in 50 short-finned pilot whales, Globicephala macrorhynchus, from two mass strandings. Based on current 1
The 6I3C and W N compositions of teeth used in combination with existing data provide dietary inf... more The 6I3C and W N compositions of teeth used in combination with existing data provide dietary information for different populations of western North Atlantic bottlenose dolphins (Ttlrsiops truncutus). The dental isotopic signatures of bottlenose dolphins collected during the 1980s significantly differ for coastal and offshore ecotypes and are consistent with reports that coastal forms feed primarily on fish whereas offshore individuals consume more squid. In a second study, the isotopic compositions of teeth from bottlenose dolphins that span a 100-yr period and data from published stomach content analyses as well as field observations made during the past 100 yr provide evidence that coastal bottlenose dolphins from the 1880s, 1920s, and 1980s had similar diets.
ABSTRACT Little is known about the ontogeny of brain size in pinnipeds despite potential function... more ABSTRACT Little is known about the ontogeny of brain size in pinnipeds despite potential functional implications of brain substrate (glucose, oxygen) requirements for diving, fasting, growth, and lactation strategies. We measured brain mass (brM) and cranial capacity (CC) in newborn and adult Weddell seals. Neonatal Weddell seals had brM that represented ~70% of adult brM. Weddell seals have the largest neonatal brain, proportional to adult brain, reported for any mammal to date, which is remarkable considering the relatively small size of Weddell seal pups at birth (6%–7% of maternal body mass) compared to neonates of other highly precocial mammals. Provision of sufficient glucose to maintain the large, well-developed brain of the neonatal Weddell seal has a nontrivial metabolic cost to both pup and mother. We therefore hypothesize that this phenomenon must have functional significance, such as allowing pups to acquire complex under-ice navigation skills during the period of maternal attendance.
North Atlantic harbour porpoises Phocoena phocoena (L.) face considerable energetic challenges, a... more North Atlantic harbour porpoises Phocoena phocoena (L.) face considerable energetic challenges, as they are relatively small marine mammals with an intense reproductive schedule and a cold-water habitat. Postnatal growth of these porpoises was described using ontogenetic allometry and body composition techniques. The cross-sectional sample contained robust calves, immature, and mature porpoises (n = 122) incidentally killed in commercial ®shing operations between 1992 and 1998. Total mass and the mass of 26 body components were measured using a standard dissection protocol. Most body components grew similarly in female and male porpoises. Blubber, brain and skull were negatively allometric, while muscle and reproductive tissues exhibited positive allometry. Female heart, liver, intestine and mesenteric lymph node grew at signi®cantly higher rates than in males. Male locomotor muscle and pelvic bones grew signi®cantly faster than in females. High growth rates for visceral and reproductive organs in porpoises, relative to other mammals, may underlie their early maturation and support their intensive, annual reproductive schedule. Relative to other cetaceans, porpoises seem to allocate a larger percentage of their total body mass to blubber. This allocation to blubber, which is greatest in calves (37% of body mass), may provide harbour porpoises with the thermal insulation required to live in cold water. The factors in¯uencing growth rates and differential investments in body composition seem to change at various stages of a porpoise's life. Energy allocation in porpoises seems to shift from an emphasis on developing an insulative blubber layer in young animals to preparing the body for annual reproduction at sexual maturity.
Bottlenose dolphins (Tursiops truncatus) collected during the 1987/88 mass mortality event along ... more Bottlenose dolphins (Tursiops truncatus) collected during the 1987/88 mass mortality event along the Atlantic coast of the United States have been analyzed for anthropogenic chemical contaminants. Average contaminant concentrations in adult males were higher than the average concentrations measured in adult females. Females could be divided into two groups by contaminant concentrations, one with low concentrations, and another with concentrations 4.4 times (PCBs) to 8.9 times (p,p'-DDE) greater. Contaminant concentrations in bottlenose were generally greater than the concentrations measured in either common (Delphinus delDhis) or white-sided (Lagenorhynchus acutus) dolphins from the western North Atlantic Ocean. A subset of animals screened for unusual chemical contaminants showed that numerous polybrominated chemicals were present, including polybrominated biphenyls and diphenyl ethers not previously found in marine mammals from U.S. coastal waters.
Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditiona... more Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditional knowledge to render a more complete description of tooth-related structures and to propose a new hypothesis for tusk function in the adult male. Gross anatomy fi ndings from computed tomography (CT) and magnetic resonance (MR) imaging and dissections of an adult male and female and one fetus, four to six months in development, were documented. Computed tomography scans rendered images of the tusks and vestigial teeth and their shared sources of innervation at the base of the tusks. Paired and asymmetrical tusks and vestigial teeth were observed in all three samples, and their relative positions reversed during development. Vestigial teeth shifted anteriorly during growth, and the developing tusks moved posteriorly as they developed. Examination of tusk microanatomy revealed the presence of a dentinal tubule network with lumena approximately 2 micrometers in diameter and 10-20 micrometers apart over the pulpal and erupted tusk surfaces. Orifi ces were present on the cementum surface indicating direct communication and sensory capability from the environment to the inner pulpal wall. Flexural strength of 95 MPa at mid tusk and 165 MPa at the base indicated resistance to high fl exural stresses. Inuit knowledge describes a tusk with remarkable and combined strength and fl exibility. Elder observations of anatomy are described by variable phenotypes and classifi ed by skin coloration, sex, and tusk expression. Behavioral observations of males leading seasonal migration groups, nonaggressive tusk encounters, and frequent sightings of smaller groups separated by sex add to the discussion of tusk function.
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Papers by charles Potter