Alzheimer's disease (AD) is the most common neurodegenerative disease and the primary cause o... more Alzheimer's disease (AD) is the most common neurodegenerative disease and the primary cause of disability and dependency among elderly humans worldwide. AD is thought to be a disease unique to humans although several other animals develop some aspects of AD‐like pathology. Odontocetes (toothed whales) share traits with humans that suggest they may be susceptible to AD. The brains of 22 stranded odontocetes of five different species were examined using immunohistochemistry to investigate the presence or absence of neuropathological hallmarks of AD: amyloid‐beta plaques, phospho‐tau accumulation and gliosis. Immunohistochemistry revealed that all aged animals accumulated amyloid plaque pathology. In three animals of three different species of odontocete, there was co‐occurrence of amyloid‐beta plaques, intraneuronal accumulation of hyperphosphorylated tau, neuropil threads and neuritic plaques. One animal showed well‐developed neuropil threads, phospho‐tau accumulation and neuriti...
Gray seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the envir... more Gray seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the environment they inhabit. Our previous research identified strains of pathogenic Campylobacter and Salmonella, originating from both human and agricultural animal hosts, on rectal swabs from live gray seal (H. grypus) pups and yearlings on the Isle of May, Scotland, UK. We examined rectal swabs from the same pup (n = 90) and yearling (n = 19) gray seals to gain further understanding into the effects of age‐related changes (pup vs. yearling) and three different natal terrestrial habitats on seal pup fecal microbiota. DNA was extracted from a subset of rectal swabs (pups n = 23, yearlings n = 9) using an optimized procedure, and the V4 region of the 16S ribosomal RNA gene was sequenced to identify each individual's microbiota. Diversity in pup samples was lower (3.92 ± 0.19) than yearlings (4.66 ± 0.39) although not significant at the p = 0.05 level (p = 0.062) but differences in the compos...
Background Chlamydia-like organisms (CLO) have been found to be present in many environmental nic... more Background Chlamydia-like organisms (CLO) have been found to be present in many environmental niches, including human sewage and agricultural run-off, as well as in a number of aquatic species worldwide. Therefore, monitoring their presence in sentinel wildlife species may be useful in assessing the wider health of marine food webs in response to habitat loss, pollution and disease. We used nasal swabs from live (n = 42) and dead (n = 50) pre-weaned grey seal pups and samples of differing natal substrates (n = 8) from an off-shore island devoid of livestock and permanent human habitation to determine if CLO DNA is present in these mammals and to identify possible sources. Results We recovered CLO DNA from 32/92 (34.7%) nasal swabs from both live (n = 17) and dead (n = 15) seal pups that clustered most closely with currently recognised species belonging to three chlamydial families: Parachlamydiaceae (n = 22), Rhabdochlamydiaceae (n = 6), and Simkaniaceae (n = 3). All DNA positive se...
Grey seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the envir... more Grey seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the environment they inhabit. Our previous research identified strains of pathogenic Campylobacter and Salmonella, originating from both human and agricultural animal hosts, on rectal swabs from live grey seal (Halichoerus grypus) pups and yearlings on the Isle of May, Scotland, UK. We examined rectal swabs from the same pup (n=90) and yearling (n=19) grey seals to gain further understanding into the effects of age-related changes (pup versus yearling) and three different natal terrestrial habitats on seal pup fecal microbiota. DNA was extracted from a subset of rectal swabs (pups n=23, yearlings n=9) using an optimized procedure, and the V4 region of the 16S rRNA gene was sequenced to identify each individual’s microbiota. Diversity in pup samples was lower (3.92 ± 0.19) than yearlings (4.66 ± 0.39) although not significant at the p=0.05 level (p = 0.062) but differences in the composition of th...
Canadian Journal of Fisheries and Aquatic Sciences, Jul 1, 1996
Nous avons mesure l'exposition totale et quotidienne de jeunes phoques gris (Halichoerus gryp... more Nous avons mesure l'exposition totale et quotidienne de jeunes phoques gris (Halichoerus grypus) a 25 congeneres de biphenyle chlore (BC) presents dans le lait des meres a l'ile de May (Ecosse) en 1990, 1991 et 1992. L'exposition totale de 36 petits nes de 13 femelles differentes variait entre 8,8 et 58,9 mg; les congeneres UICPA CB-153 et CB-138 etaient les composantes principales dans le lait, ou ils representaient 42,1% de l'exposition totale aux BC. La quantite de lait consommee chaque jour par les petits et la teneur en lipides de ce lait augmentaient pendant la lactation. En consequence, l'exposition quotidienne aux BC a augmente fortement pendant la premiere moitie de la periode d'allaitement de 18 jours. Il y avait des differences significatives entre les femelles dans les concentrations de BC dans le lait et dans la contribution relative des differents congeneres a l'exposition totale aux BC. Lorsqu'on eliminait les effets des variations entre femelles, on observait des changements significatifs dans les concentrations de BC moins chlores pendant la lactation et d'une annee a l'autre. On peut estimer de facon precise l'exposition d'un petit phoque gris aux BC si l'on connait l'identite de sa mere, sa masse au moment du sevrage et la concentration de BC dans un echantillon de lait preleve vers la fin de l'allaitement.
Wildlife populations and their habitats are exposed to an expanding diversity and intensity of st... more Wildlife populations and their habitats are exposed to an expanding diversity and intensity of stressors caused by human activities, within the broader context of natural processes and increasing pressure from climate change. Estimating how these multiple stressors affect individuals, populations, and ecosystems is thus of growing importance. However, their combined effects often cannot be predicted reliably from the individual effects of each stressor, and we lack the mechanistic understanding and analytical tools to predict their joint outcomes. We review the science of multiple stressors and present a conceptual framework that captures and reconciles the variety of existing approaches for assessing combined effects. Specifically, we show that all approaches lie along a spectrum, reflecting increasing assumptions about the mechanisms that regulate the action of single stressors and their combined effects. An emphasis on mechanisms improves analytical precision and predictive power but could introduce bias if the underlying assumptions are incorrect. A purely empirical approach has less risk of bias but requires adequate data on the effects of the full range of anticipated combinations of stressor types and magnitudes. We illustrate how this spectrum can be formalised into specific analytical methods, using an example of North Atlantic right whales feeding on limited prey resources while simultaneously being affected by entanglement in fishing gear. In practice, case-specific management needs and data availability will guide the exploration of the stressor combinations of interest and the selection of a suitable trade-off between precision and bias. We argue that the primary goal for adaptive management should be to identify the most practical and effective ways to remove or reduce specific combinations of stressors, bringing the risk of adverse impacts on populations and ecosystems below acceptable thresholds.
Understanding the ecology and evolution of wildlife and domesticated species requires knowledge o... more Understanding the ecology and evolution of wildlife and domesticated species requires knowledge of their physiological responses to environmental change and the constraints under which they operate. However, whole animal experiments are often limited in sample size and can be logistically and ethically challenging. Culture techniques represent a powerful approach, but are used infrequently in field research due to practical constraints. We used minimal tissue culture equipment in a remote field site for in vitro explant experiments using blubber from wild grey seals Halichoerus grypus. Assessing explant viability and detecting microbial contamination in remote field sites, where facilities are often small, unspecialised and more vulnerable to bacterial or fungal infection, present major challenges. We investigated whether oxygen‐sensitive planar optodes (OSPO) in closed system respirometry could be used to assess oxygen consumption by blubber explants from suckling and fasting wild ...
A regime shift is a large, sudden, and long‐lasting change in the dynamics of an ecosystem, affec... more A regime shift is a large, sudden, and long‐lasting change in the dynamics of an ecosystem, affecting multiple trophic levels. There are a growing number of papers that report regime shifts in marine ecosystems. However, the evidence for regime shifts is equivocal, because the methods used to detect them are not yet well developed. We have collated over 300 biological time series from seven marine regions around the UK, covering the ecosystem from phytoplankton to marine mammals. Each time series consists of annual measures of abundance for a single group of organisms over several decades. We summarised the data for each region using the first principal component, weighting either each time series or each biological component (e.g. plankton, fish, benthos) equally. We then searched for regime shifts using Rodionov’s regime shift detection (RSD) method, which found regime shifts in the first principal component for all seven marine regions. However, there are consistent temporal tren...
Harmful algal bloom events are increasing in a number of water bodies around the world with signi... more Harmful algal bloom events are increasing in a number of water bodies around the world with significant economic impacts on the aquaculture, fishing and tourism industries. As well as their potential impacts on human health, toxin exposure from harmful algal blooms (HABs) has resulted in widespread morbidity and mortality in marine life, including top marine predators. There is therefore a need for an improved understanding of the trophic transfer, and persistence of toxins in marine food webs. For the first time, the concentrations of two toxin groups of commercial and environmental importance, domoic acid (DA) and saxitoxin (including Paralytic Shellfish Toxin (PST) analogues), were measured in the viscera of 40 different fish species caught in Scotland between February and November, 2012 to 2019. Overall, fish had higher concentrations of DA compared to PSTs, with a peak in the summer / autumn months. Whole fish concentrations were highest in pelagic species including Atlantic mackerel and herring, key forage fish for marine predators including seals, cetaceans and seabirds. The highest DA concentrations were measured along the east coast of Scotland and in Orkney. PSTs showed highest concentrations in early summer, consistent with phytoplankton bloom timings. The detection of multiple toxins in such a range of demersal, pelagic and benthic fish prey species suggests that both the fish, and by extension, piscivorous marine predators, experience multiple routes of toxin exposure. Risk assessment models to understand the impacts of exposure to HAB toxins on marine predators therefore need to consider how chronic, low-dose exposure to multiple toxins, as well as acute exposure during a bloom, could lead to potential long-term health effects ultimately contributing to mortalities. The potential synergistic, neurotoxic and physiological effects of long-term exposure to multiple toxins require investigation in order to appropriately assess the risks of HAB toxins to fish as well as their predators.
Alzheimer's disease (AD) is the most common neurodegenerative disease and the primary cause o... more Alzheimer's disease (AD) is the most common neurodegenerative disease and the primary cause of disability and dependency among elderly humans worldwide. AD is thought to be a disease unique to humans although several other animals develop some aspects of AD‐like pathology. Odontocetes (toothed whales) share traits with humans that suggest they may be susceptible to AD. The brains of 22 stranded odontocetes of five different species were examined using immunohistochemistry to investigate the presence or absence of neuropathological hallmarks of AD: amyloid‐beta plaques, phospho‐tau accumulation and gliosis. Immunohistochemistry revealed that all aged animals accumulated amyloid plaque pathology. In three animals of three different species of odontocete, there was co‐occurrence of amyloid‐beta plaques, intraneuronal accumulation of hyperphosphorylated tau, neuropil threads and neuritic plaques. One animal showed well‐developed neuropil threads, phospho‐tau accumulation and neuriti...
Gray seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the envir... more Gray seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the environment they inhabit. Our previous research identified strains of pathogenic Campylobacter and Salmonella, originating from both human and agricultural animal hosts, on rectal swabs from live gray seal (H. grypus) pups and yearlings on the Isle of May, Scotland, UK. We examined rectal swabs from the same pup (n = 90) and yearling (n = 19) gray seals to gain further understanding into the effects of age‐related changes (pup vs. yearling) and three different natal terrestrial habitats on seal pup fecal microbiota. DNA was extracted from a subset of rectal swabs (pups n = 23, yearlings n = 9) using an optimized procedure, and the V4 region of the 16S ribosomal RNA gene was sequenced to identify each individual's microbiota. Diversity in pup samples was lower (3.92 ± 0.19) than yearlings (4.66 ± 0.39) although not significant at the p = 0.05 level (p = 0.062) but differences in the compos...
Background Chlamydia-like organisms (CLO) have been found to be present in many environmental nic... more Background Chlamydia-like organisms (CLO) have been found to be present in many environmental niches, including human sewage and agricultural run-off, as well as in a number of aquatic species worldwide. Therefore, monitoring their presence in sentinel wildlife species may be useful in assessing the wider health of marine food webs in response to habitat loss, pollution and disease. We used nasal swabs from live (n = 42) and dead (n = 50) pre-weaned grey seal pups and samples of differing natal substrates (n = 8) from an off-shore island devoid of livestock and permanent human habitation to determine if CLO DNA is present in these mammals and to identify possible sources. Results We recovered CLO DNA from 32/92 (34.7%) nasal swabs from both live (n = 17) and dead (n = 15) seal pups that clustered most closely with currently recognised species belonging to three chlamydial families: Parachlamydiaceae (n = 22), Rhabdochlamydiaceae (n = 6), and Simkaniaceae (n = 3). All DNA positive se...
Grey seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the envir... more Grey seals (Halichoerus grypus) can act as sentinel species reflecting the condition of the environment they inhabit. Our previous research identified strains of pathogenic Campylobacter and Salmonella, originating from both human and agricultural animal hosts, on rectal swabs from live grey seal (Halichoerus grypus) pups and yearlings on the Isle of May, Scotland, UK. We examined rectal swabs from the same pup (n=90) and yearling (n=19) grey seals to gain further understanding into the effects of age-related changes (pup versus yearling) and three different natal terrestrial habitats on seal pup fecal microbiota. DNA was extracted from a subset of rectal swabs (pups n=23, yearlings n=9) using an optimized procedure, and the V4 region of the 16S rRNA gene was sequenced to identify each individual’s microbiota. Diversity in pup samples was lower (3.92 ± 0.19) than yearlings (4.66 ± 0.39) although not significant at the p=0.05 level (p = 0.062) but differences in the composition of th...
Canadian Journal of Fisheries and Aquatic Sciences, Jul 1, 1996
Nous avons mesure l'exposition totale et quotidienne de jeunes phoques gris (Halichoerus gryp... more Nous avons mesure l'exposition totale et quotidienne de jeunes phoques gris (Halichoerus grypus) a 25 congeneres de biphenyle chlore (BC) presents dans le lait des meres a l'ile de May (Ecosse) en 1990, 1991 et 1992. L'exposition totale de 36 petits nes de 13 femelles differentes variait entre 8,8 et 58,9 mg; les congeneres UICPA CB-153 et CB-138 etaient les composantes principales dans le lait, ou ils representaient 42,1% de l'exposition totale aux BC. La quantite de lait consommee chaque jour par les petits et la teneur en lipides de ce lait augmentaient pendant la lactation. En consequence, l'exposition quotidienne aux BC a augmente fortement pendant la premiere moitie de la periode d'allaitement de 18 jours. Il y avait des differences significatives entre les femelles dans les concentrations de BC dans le lait et dans la contribution relative des differents congeneres a l'exposition totale aux BC. Lorsqu'on eliminait les effets des variations entre femelles, on observait des changements significatifs dans les concentrations de BC moins chlores pendant la lactation et d'une annee a l'autre. On peut estimer de facon precise l'exposition d'un petit phoque gris aux BC si l'on connait l'identite de sa mere, sa masse au moment du sevrage et la concentration de BC dans un echantillon de lait preleve vers la fin de l'allaitement.
Wildlife populations and their habitats are exposed to an expanding diversity and intensity of st... more Wildlife populations and their habitats are exposed to an expanding diversity and intensity of stressors caused by human activities, within the broader context of natural processes and increasing pressure from climate change. Estimating how these multiple stressors affect individuals, populations, and ecosystems is thus of growing importance. However, their combined effects often cannot be predicted reliably from the individual effects of each stressor, and we lack the mechanistic understanding and analytical tools to predict their joint outcomes. We review the science of multiple stressors and present a conceptual framework that captures and reconciles the variety of existing approaches for assessing combined effects. Specifically, we show that all approaches lie along a spectrum, reflecting increasing assumptions about the mechanisms that regulate the action of single stressors and their combined effects. An emphasis on mechanisms improves analytical precision and predictive power but could introduce bias if the underlying assumptions are incorrect. A purely empirical approach has less risk of bias but requires adequate data on the effects of the full range of anticipated combinations of stressor types and magnitudes. We illustrate how this spectrum can be formalised into specific analytical methods, using an example of North Atlantic right whales feeding on limited prey resources while simultaneously being affected by entanglement in fishing gear. In practice, case-specific management needs and data availability will guide the exploration of the stressor combinations of interest and the selection of a suitable trade-off between precision and bias. We argue that the primary goal for adaptive management should be to identify the most practical and effective ways to remove or reduce specific combinations of stressors, bringing the risk of adverse impacts on populations and ecosystems below acceptable thresholds.
Understanding the ecology and evolution of wildlife and domesticated species requires knowledge o... more Understanding the ecology and evolution of wildlife and domesticated species requires knowledge of their physiological responses to environmental change and the constraints under which they operate. However, whole animal experiments are often limited in sample size and can be logistically and ethically challenging. Culture techniques represent a powerful approach, but are used infrequently in field research due to practical constraints. We used minimal tissue culture equipment in a remote field site for in vitro explant experiments using blubber from wild grey seals Halichoerus grypus. Assessing explant viability and detecting microbial contamination in remote field sites, where facilities are often small, unspecialised and more vulnerable to bacterial or fungal infection, present major challenges. We investigated whether oxygen‐sensitive planar optodes (OSPO) in closed system respirometry could be used to assess oxygen consumption by blubber explants from suckling and fasting wild ...
A regime shift is a large, sudden, and long‐lasting change in the dynamics of an ecosystem, affec... more A regime shift is a large, sudden, and long‐lasting change in the dynamics of an ecosystem, affecting multiple trophic levels. There are a growing number of papers that report regime shifts in marine ecosystems. However, the evidence for regime shifts is equivocal, because the methods used to detect them are not yet well developed. We have collated over 300 biological time series from seven marine regions around the UK, covering the ecosystem from phytoplankton to marine mammals. Each time series consists of annual measures of abundance for a single group of organisms over several decades. We summarised the data for each region using the first principal component, weighting either each time series or each biological component (e.g. plankton, fish, benthos) equally. We then searched for regime shifts using Rodionov’s regime shift detection (RSD) method, which found regime shifts in the first principal component for all seven marine regions. However, there are consistent temporal tren...
Harmful algal bloom events are increasing in a number of water bodies around the world with signi... more Harmful algal bloom events are increasing in a number of water bodies around the world with significant economic impacts on the aquaculture, fishing and tourism industries. As well as their potential impacts on human health, toxin exposure from harmful algal blooms (HABs) has resulted in widespread morbidity and mortality in marine life, including top marine predators. There is therefore a need for an improved understanding of the trophic transfer, and persistence of toxins in marine food webs. For the first time, the concentrations of two toxin groups of commercial and environmental importance, domoic acid (DA) and saxitoxin (including Paralytic Shellfish Toxin (PST) analogues), were measured in the viscera of 40 different fish species caught in Scotland between February and November, 2012 to 2019. Overall, fish had higher concentrations of DA compared to PSTs, with a peak in the summer / autumn months. Whole fish concentrations were highest in pelagic species including Atlantic mackerel and herring, key forage fish for marine predators including seals, cetaceans and seabirds. The highest DA concentrations were measured along the east coast of Scotland and in Orkney. PSTs showed highest concentrations in early summer, consistent with phytoplankton bloom timings. The detection of multiple toxins in such a range of demersal, pelagic and benthic fish prey species suggests that both the fish, and by extension, piscivorous marine predators, experience multiple routes of toxin exposure. Risk assessment models to understand the impacts of exposure to HAB toxins on marine predators therefore need to consider how chronic, low-dose exposure to multiple toxins, as well as acute exposure during a bloom, could lead to potential long-term health effects ultimately contributing to mortalities. The potential synergistic, neurotoxic and physiological effects of long-term exposure to multiple toxins require investigation in order to appropriately assess the risks of HAB toxins to fish as well as their predators.
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