Jonna A. K. Mazet

Southern Sea Otter as a Sentinel of Marine Ecosystem Health

The southern sea otter (Enhydra lutris nereis) is listed as “threatened” under the Endangered Species Act (ESA) and is a “keystone species,” strongly influencing the abundance and diversity of the other species within its kelp forest ecosystem. This is accomplished primarily by preying upon urchins that eat the kelp stipe and holdfast, which can reduce a kelp forest to an urchin barren. Sea otters are very susceptible to marine pollutants such as petroleum, which may be directly toxic and/or alter their fur’s insulating properties. Sea otters are an excellent sentinel species. They eat approximately 25% of their body weight per day in shellfish and other invertebrates, and can concentrate and integrate chemical contaminants. In addition, they appear to be susceptible to a number of diseases and parasites that may have anthropogenic origins, and shellfish may serve as an intermediary for some of these infections. Many of the shellfish the otters eat are also harvested for human food. In their role as sentinels, sea otter health has implications for human health, economic sustainability of shellfisheries, as well as overall marine ecosystem health. The recent southern sea otter decline has been viewed with some alarm by conservationists and, indeed, recovery seems a long way off. High mortality rather than depressed recruitment appears to underlie the decline. A good deal of debate has centered on the role of infectious diseases and parasites, exposure to contaminants, nutrition and prey availability, net and pot fishery interactions, and other sources of mortality. Current research is being done related to major classes of mortality, various types of pollutants and some specific organisms causing southern sea otter mortality, and their implications for marine ecosystem health and sustainability.

Rabies Virus and Canine Distemper Virus in Wild and Domestic Carnivores in Northern Kenya: Are Domestic Dogs the Reservoir?

Rabies virus (RV) and canine distemper virus (CDV) can cause significant mortality in wild carnivore populations, and RV threatens human lives. We investigated serological patterns of exposure to CDV and RV in domestic dogs (Canis familiaris), African wild dogs (Lycaon pictus), black-backed jackals (Canis mesomelas), spotted hyenas (Crocuta crocuta), striped hyenas (Hyaena hyaena) and African lions (Panthera leo), over a 10-year period, in a Kenyan rangeland to assess the role domestic dogs may play in the transmission dynamics of these two important canid pathogens. Observed patterns of RV exposure suggested that repeated introduction, rather than maintenance, occurred in the wild carnivore species studied. However, RV appeared to have been maintained in domestic dogs: exposure was more likely in domestic dogs than in the wild carnivores; was detected consistently over time without variation among years; and was detected in juveniles (≤1-year-old) as well as adults (>1-year-old). We conclude that this domestic dog population could be a RV reservoir. By contrast, the absence of evidence of CDV exposure for each carnivore species examined in the study area, for specific years, suggested repeated introduction, rather than maintenance, and that CDV may require a larger reservoir population than RV. This reservoir could be a larger domestic dog population; another wildlife species; or a “metareservoir” consisting of multiple interconnected carnivore populations. Our findings suggest that RV risks to people and wild carnivores might be controlled by domestic dog vaccination, but that CDV control, if required, would need to target the species of concern.

Toxoplasma gondii, Source to Sea: Higher Contribution of Domestic Felids to Terrestrial Parasite Loading Despite Lower Infection Prevalence

Environmental transmission of Toxoplasma gondii, a global zoonotic parasite, adversely impacts human and animal health. Toxoplasma is a significant cause of mortality in threatened Southern sea otters, which serve as sentinels for disease threats to people and animals in coastal environments. As wild and domestic felids are the only recognized hosts capable of shedding Toxoplasma oocysts into the environment, otter infection suggests land-to-sea pathogen transmission. To assess relative contributions to terrestrial parasite loading, we evaluated infection and shedding among managed and unmanaged feral domestic cats, mountain lions, and bobcats in coastal California, USA. Infection prevalence differed among sympatric felids, with a significantly lower prevalence for managed feral cats (17%) than mountain lions, bobcats, or unmanaged feral cats subsisting on wild prey (73–81%). A geographic hotspot of infection in felids was identified near Monterey Bay, bordering a high-risk site for otter infection. Increased odds of oocyst shedding were detected in bobcats and unmanaged feral cats. Due to their large populations, pet and feral domestic cats likely contribute more oocysts to lands bordering the sea otter range than native wild felids. Continued coastal development may influence felid numbers and distribution, increase terrestrial pathogens in freshwater runoff, and alter disease dynamics at the human–animal–environment interface.

Aquatic polymers can drive pathogen transmission in coastal ecosystems

Gelatinous polymers including extracellular polymeric substances (EPSs) are fundamental to biophysical processes in aquatic habitats, including mediating aggregation processes and functioning as the matrix of biofilms. Yet insight into the impact of these sticky molecules on the environmental transmission of pathogens in the ocean is limited. We used the zoonotic parasite Toxoplasma gondii as a model to evaluate polymer-mediated mechanisms that promote transmission of terrestrially derived pathogens to marine fauna and humans. We show that transparent exopolymer particles, a particulate form of EPS, enhance T. gondii association with marine aggregates, material consumed by organisms otherwise unable to access micrometre-sized particles. Adhesion to EPS biofilms on macroalgae also captures T. gondii from the water, enabling uptake of pathogens by invertebrates that feed on kelp surfaces. We demonstrate the acquisition, concentration and retention of T. gondii by kelp-grazing snails, which can transmit T. gondii to threatened California sea otters. Results highlight novel mechanisms whereby aquatic polymers facilitate incorporation of pathogens into food webs via association with particle aggregates and biofilms. Identifying the critical role of invisible polymers in transmission of pathogens in the ocean represents a fundamental advance in understanding and mitigating the health impacts of coastal habitat pollution with contaminated runoff.

Integrating the Management of Ruaha Landscape of Tanzania with Local Needs and Preferences

Sustainable management of landscapes with multiple competing demands such as the Ruaha Landscape is complex due to the diverse preferences and needs of stakeholder groups involved. This study uses conjoint analysis to assess the preferences of representatives from three stakeholder groups—local communities, district government officials, and non-governmental organizations—toward potential solutions of conservation and development tradeoffs facing local communities in the Ruaha Landscape of Tanzania. Results demonstrate that there is little consensus among stakeholders about the best development strategies for the Ruaha region. This analysis suggests a need for incorporating issues deemed important by these various groups into a development strategy that aims to promote conservation of the Ruaha Landscape and improve the livelihood of local communities.

Oiled Wildlife Care Network Development for Integrated Emergency Response1

ABSTRACT In response to the potential risk to California from oil spill events, the Lempert-Keene-Seastrand Oil Spill Prevention and Response Act was passed in 1990 requiring the Administrator of t...

Rehabilitation of oiled wildlife: Why do it ?

ABSTRACT Although the publics interest in oil spills and similar environmental disasters often focus on the plight of injured animals, animal issues are only a very small part of an oil spill resp...

Awareness and Practices Relating to Zoonotic Diseases Among Smallholder Farmers in Nepal

AbstractIncreasing livestock production to meet growing demands has resulted in greater interactions at the livestock–wildlife–human interface and more opportunities for zoonotic disease spread. Zoonoses impose enormous burdens on low-income countries like Nepal, where populations are largely dependent on livestock production and access to shared grazing lands, often near protected areas, due to population pressures. Several livestock-associated zoonoses have been reported in Nepal; however, little is known regarding Nepali farmers’ knowledge of zoonoses and opportunities for disease management. We conducted a cross-sectional study to investigate Nepali farmers’ awareness of zoonoses, assess current health challenges, and evaluate disease prevention and control practices. We found that awareness of zoonotic pathogens was limited, especially in informally educated and illiterate farmers; the majority of which were women. Further, farmers’ preventive herd health, food safety, and sanitation practices were not associated with their awareness. Several farmers reported high-risk practices despite being aware of zoonotic diseases, suggesting a disconnect between the farmers’ awareness and practice. Our study highlights the need for improving Nepali farmers’ knowledge of zoonoses and disease prevention measures. Closing these awareness-practice gaps will require an improved understanding of risk and effective drivers of behavior change, alongside engagement of farmers in development of zoonotic disease prevention programs that encourage participation of both male and female farmers across all levels of education.