The Role of Canine Distemper Virus and Persistent Organic Pollutants in Mortality Patterns of Caspian Seals (Pusa caspica)

Wilson, Susan C.; Eybatov, T.; Amano, Masao; Jepson, Paul D.; Goodman, Simon J.

doi:10.1371/journal.pone.0099265

Cited by 27 publications

(25 citation statements)

References 55 publications

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“…However, any change in the contaminant level in the population of adult females would be gradual and not cause extreme variation among years. Moreover, the most recent contaminant data available collected during the 2000−2001 canine distemper virus (CDV) outbreak suggest contaminant concentrations are below the threshold for large impacts on fertility (Helle et al 1976, Wilson et al 2014.…”

Section: Variation Among the Years 2005 To 2012mentioning

confidence: 99%

Inter-year variation in pup production of Caspian seals Pusa caspica 2005–2012 determined from aerial surveys

Dmitrieva¹,

Härkönen²,

Baimukanov³

et al. 2015

Endang. Species. Res.

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Assessing species abundance and reproductive output is crucial for evaluations of population dynamics, conservation status and the development of management objectives. The Caspian seal Pusa caspica is a key predator in the Caspian Sea ecosystem and is listed as Endangered by the IUCN. Here we report on fixed-wing aerial strip transect surveys of the breeding population on the Caspian Sea winter ice field carried out in February, 2005−2012. Potential detection biases were estimated by applying a Petersen mark-recapture estimator to the counts from double photographic observations. We also tested for effects of weather conditions on count results, and for correlations between pup production and ice conditions and net primary productivity (npp). Fluctuations in pup production estimates were observed among years, ranging from 8200 pups (95% CI: 7130−9342) in 2010 to 34 000 (95% CI: 31 275−36 814) in 2005. Total adults on the ice ranged from 14 500 in 2010 to 66 300 in 2012. We did not detect significant associations between pup production and either ice summary data (ice season length and ice area) or npp. The observed inter-year variation may be partly due to underlying biological drivers influencing the fecundity of the population, although measurement errors arising from observation bias, plus variation in survey timing and weather conditions may also have contributed. Identifying the potential drivers of Caspian seal population dynamics will require extending both the survey time series and the quality of supporting data. However, inter-year fluctuations should still cause concern that the population may be vulnerable to environmental variability and ecosystem dynamics.

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Section: Variation Among the Years 2005 To 2012mentioning

confidence: 99%

Inter-year variation in pup production of Caspian seals Pusa caspica 2005–2012 determined from aerial surveys

Dmitrieva¹,

Härkönen²,

Baimukanov³

et al. 2015

Endang. Species. Res.

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“…In pinnipeds, relatively 'fatter' animals are more efficient divers (Adachi et al 2014) and may be better able to exploit deeper habitats, which is consistent with our observation of deep divers having higher post-moult BMI. Alternatively, while it is not possible to estimate the age of mature Caspian seals precisely on the basis of body length, mature seals do continue to grow through adult life (Wilson et al 2014) so that on average, in our study, shallow divers may have been older than deep divers. Shallow divers' foraging locations were concentrated around the inflow of the Volga delta, which has some of the highest NPP in the Caspian.…”

Section: Individual Variation In Foraging and Diving Behaviourmentioning

confidence: 81%

“…Comparison of body lengths to male and female growth curves for Caspian seals (Wilson et al 2014), suggest that all the animals were sexually mature individuals. Body length was measured as linear nose to tip of tail distance along the side of the animal.…”

Section: Study Sites Instrumentation and Data Collectionmentioning

confidence: 94%

“…only 9 females (compared to 24 males) contributed to the summer season data. There is limited sexual dimorphism in Caspian seals (Wilson et al 2014), and it is unclear whether energetic demands might vary significantly among sexes. Females have costs due to pregnancy and lactation, while males may experience costs due to competition, display and maintaining territories during breeding.…”

Section: Individual Variation In Foraging and Diving Behaviourmentioning

confidence: 99%

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Individual variation in seasonal movements and foraging strategies of a land-locked, ice-breeding pinniped

Dmitrieva¹,

Jüssi²,

Jüssi³

et al. 2016

Mar. Ecol. Prog. Ser.

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Marine mammal satellite telemetry studies can provide important tests of movement and foraging theory. Here we present the first satellite tracking study of Caspian seals Pusa caspica, an endangered, ice-breeding phocid seal, endemic to the Caspian Sea. The Caspian Sea is one of the most variable habitats inhabited by any pinniped species, and lacks competing large piscivores. Under such conditions foraging theory predicts that individual variation in foraging strategy may develop to reduce intra-species competition. We deployed 75 Argos satellite tags from 2009 to 2012 on adult seals of both sexes, and used state-space modelling to describe movement, and behavioural states. During winter in all years most individuals were mobile within the icepack, making repeated trips into open water outside the ice field, with only brief stationary periods that may have been related to breeding activity. During summer 2011, 60% of tagged animals migrated into the mid and southern Caspian, while the remainder spent the ice-free season in the north. Summer foraging locations were not restricted by proximity to haul-out sites, with animals spending more than 6 months at sea. Maximum dive depths exceeded 200 m, and maximum duration was greater than 20 min, but 80% of dives were shallower than 15 m and shorter than 5 min. Hierarchical cluster analysis identified 3 distinct groups of summer dive behaviour, comprising shallow, intermediate and deep divers, which were also spatially exclusive, suggesting potential niche partitioning and individual specialisation on prey or habitat types. The results can contribute to assessment of impacts from anthropogenic activities and to designation of protected areas encompassing critical habitats.

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“…CDV affects a wide variety of carnivore species, including mustelids, procyonids, ursids, canids (domestic and wild), felids and marine mammals [2,[28][29][30]. It is considered among the most widespread multi-host pathogens [31].…”

Section: Plos Onementioning

confidence: 99%

Development and validation of a portable, point-of-care canine distemper virus qPCR test

et al. 2020

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Canine distemper virus (CDV) is a multi-host pathogen that can cause significant mortality in domestic, wild terrestrial and marine mammals. It is a major conservation threat in some endangered species. Infection can result in severe respiratory disease and fatal encephalitis. Diagnosis and disease monitoring in wildlife, and differentiation of CDV from rabies (a lifethreatening zoonotic disease that can produce similar neurologic signs), would benefit from the availability of a portable, point-of-care (POC) diagnostic test. We therefore developed a quantitative RT-PCR assay for CDV using shelf-stable, lyophilized reagents and target-specific primers and probes for use with the handheld Biomeme two3™ qPCR thermocycler. Biomeme's extraction methodology, lyophilized reagents, and thermocycler were compared to our standard laboratory-based methods to assess sensitivity, efficiency and overall test performance. Results using a positive control plasmid for CDV showed comparable sensitivity (detection of 50 copies) and PCR efficiency between the two platforms, and CDV detection was similar between platforms when tested using a modified live CDV vaccine. Significantly higher Ct values (average Ct = 5.1 cycles) were observed using the Biomeme platform on known CDV positive animal samples. CDV detection using the Biomeme platform was similar in 25 of 26 samples from suspect CDV cases when compared to standard virology laboratory testing. One false positive was observed that was negative upon retest. The Biomeme methodology can be adapted for detection of specific targets, and this portable technology saves time by eliminating the need for local or international sample transport for laboratory-based diagnostics. However, results of our testing suggest that decreased diagnostic sensitivity (higher Ct values) relative to laboratory-based methods was observed using animal samples, so careful validation and optimization are essential. Portable qPCR platforms can empower biologists and wildlife health professionals in remote and low-resource settings, which will greatly improve our understanding of CDV disease ecology and associated conservation threats in wildlife.

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The Role of Canine Distemper Virus and Persistent Organic Pollutants in Mortality Patterns of Caspian Seals (Pusa caspica)

Cited by 27 publications

References 55 publications

Inter-year variation in pup production of Caspian seals Pusa caspica 2005–2012 determined from aerial surveys

Inter-year variation in pup production of Caspian seals Pusa caspica 2005–2012 determined from aerial surveys

Individual variation in seasonal movements and foraging strategies of a land-locked, ice-breeding pinniped

Development and validation of a portable, point-of-care canine distemper virus qPCR test

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