Climate change leads to spread of phocine distemper virus in North Pacific 

UC Davis researchers at the One Health Institute, in collaboration with other co-authoring institutions, have linked the loss of sea ice in the Arctic with the emergence of a deadly virus in marine mammals in the North Pacific, according to a study published on Nov. 7 in the journal “Scientific Reports.”

After phocine distemper virus (PDV) was identified in northern sea otters in Alaska in 2004, scientists wanted to know how this pathogen, that previously had only been found in the North Atlantic, reached the Pacific Ocean. Upon completing the 15-year study, the researchers discovered that the decline of sea ice in the Arctic has opened up new pathways to spread the pathogen between marine mammal species, according to Tracey Goldstein, the associate director of the One Health Institute at the UC Davis School of Veterinary Medicine and one of the principal investigators of the study. 

“Sea otters aren’t migratory, so we wondered how viruses from the Atlantic got into animals in the Pacific and how it was introduced,” Goldstein said.

For this study, the One Health Institute brought together multidisciplinary teams to look at the intersection of human, environmental and animal health impacts of this pathogen in the Arctic, according to Jonna Mazet, the executive director of the One Health Institute and the other principal investigator of this study. 

“Members of the marine mammal community all came together to work with us at UC  Davis because we were concerned about the pathogen in the Arctic that didn’t belong in the Pacific Ocean,” Mazet said.

According to Mazet, PDV killed thousands of European harbor seals in the North Atlantic in 2002, so its recent emergence in the Pacific Ocean poses a serious threat to the mammals that live there.

“We are like disease detectives to find out why [PDV] is showing up in marine animals in an ocean that it should not be in,” Mazet said. 

After pooling data from 2001–2016, researchers found a pattern that illustrates how  melting sea ice allows marine mammals to move further into the Arctic and make contact with Pactific Ocean species. The 2002 outbreak in European harbor seals in the North Atlantic occurred in September, which is the time of year when ice is lowest. Also, 2002 was the first year the Arctic channel had an opening in the ice, Goldstein said

“Antibodies told us there had been exposure in 2003 in pups,” Goldstein said. “The moms might have been exposed earlier in 2002 or 2003.”

A second peak in an outbreak of the virus occurred in 2009, following the same pattern as the 2002 outbreak, since there was an opening in the Arctic ice again in 2008. Scientists believe infected marine mammals reintroduced PDV in the North Pacific, according to Goldstein. 

“There is variability from year to year with how many [marine mammals] are injected, but there is evidence that there are long-term changes due to climate change,” said Elizabeth VanWormer, a postdoctoral researcher at UC Davis during the study and the first author in the paper. “Since 2008, the ice in the Arctic has been open almost every year, creating many more opportunities for diseases to be shared across oceans.” 

Climate scientists have provided good evidence to link climate change to the reason for the decline in sea ice and the acceleration in the cycles of sea ice change, according to Mazet. 

“This is direct evidence that there are health threats due to the climate crisis,” Mazet said. “Climate critics will point to how they think it’s going to take decades to know if [climate change] is true, but this study shows it is true. These animals are giving us a very clear warning sign to do something now.”

The marine mammals that were researched in the study include Steller sea lions, northern sea otters, northern fur seals, spotted seals, gray seals, harbor seals, harp seals, ribbon seals, bearded seals, ribbon seals and ring seals, VanWormer said.

 “We studied pretty diverse populations over time, which helped us understand how the virus was moving among populations,” VanWormer said. 

Researchers found that each mammal reacted differently to the disease, some more negatively than others.

“Harbor seals are very susceptible to disease, and they get sick and die,” Goldstein said. “Gray seals don’t always get very sick and share the disease. Harp seal are carriers and give it to other animals in the Arctic. Sea lions and northern fur seals, ribbon seals, ring seals, spotted seals and sea otters can all be infected but we are not sure [about] all of the effects [they experience].”

After conducting this research, Goldstein said the pathogen is more widespread than previously thought and can infect many different animals. Since the Arctic ice has been open almost every year since 2008, diseases can spread more easily. 

“As the environment changes, it affects animal health and affects human health,” Goldstein said. “It is all linked and holistically affect each other.” 

Researchers were concerned that the pathogen could harm people who live in the Arctic and hunt marine mammals through traditional practices. No evidence has shown the pathogen causes harm to humans, Mazet said, but it can impact the people who depend on marine mammals in other ways. 

“Up in the Arctic, for Native Alaskans, these animals are really important for people,” Goldstein said. “As animals are affected, people are affected as well. People, animals and the environment are all very connected. Climate change increases the effects on the livelihood of the people in the Arctic.” 

In addition to UC Davis’ contributions, other co-authoring institutions include the University of Saint Andrews, U.S. Fish and Wildlife Service, National Marine Fisheries Service (NOAA Fisheries), Alaska Fisheries Science Center’s Marine Mammal Laboratory, University of Glasgow, Alaska Department of Fish and Game, University of Alaska-Fairbanks, Queen’s University Belfast, Pirbright Institute and Alaska Veterinary Pathology Service.

“By collaborating with one another, we could pool data together,” Mazet said.

Funding for the study was granted by the Morris Animal Foundation, NOAA Oceans and Human Health Graduate Traineeship Program, the Alaska Fisheries Science Center Marine Mammal Laboratory and the U.S. Fish and Wildlife Service.

Because of the high impact of this study on animals, humans and the environment, the Morris Animal Foundation (MAF) granted the study a total of $70,152 between August 2009 to October 2012, according to Kelly Diehl, the senior director of science and communications at the MAF. The foundation understands how wildlife can have great effects on the rest of the world. 

“I’m really proud of [the] foundation for dipping their toe in this controversial topic, and for not being afraid to fund it,” Diehl said. “If the science is solid, we want to fund it. It is important to do solid science that adds to conversation when a topic is controversial.”

Even though their paper has already been published, researchers are continuing their work on this topic. The published study contains samples through 2016, so now scientists are studying samples collected from the last two years to assess the virus’ current status in the Arctic, Goldstein said. 

“We want to continue to monitor this,” Goldstein said. “In the Atlantic ocean, we see cycles of the virus peaking between five to 10 years, but in the Pacitifc we see there are different peaks. We want to know the next time [an outbreak] happens and if any deaths happen.”

Written by: Margo Rosenbaum — science@theaggie.org 

Planting genetically resilient forest in effort to battle forest fires, climate change

Tree populations in the Sierra Nevada area have seen a considerable decrease in health and density. Between 2012 and 2016, the area lost more than 129 million trees. Patricia Maloney, UC Davis biologist and scientist in the UC Davis Department of Plant Pathology and Tahoe Environmental Research Center, attributes this increased mortality — specifically of sugar pine trees — to a combination of drought and mountain pine beetle outbreak. 

In an effort to combat this rapid decline, Maloney and a team of researchers collected seeds from 100 surviving trees in the Lake Tahoe basin to perform a sugar pine reforestation. The project, Maloney said, originates from a question she asked her colleague: “Can we detect the genetic consequences of historical logging on sugar pine in the basin?”

The subsequent research conducted by her colleague Andrew Eckert, a professor of biology at Virginia Commonwealth University, revealed an important idea. Eckert’s data indicated that historical logging not only reduced population sizes, but also removed genetic material inherent to the sugar pine. 

Eckert is a collaborator in the sugar pine reforestation project, working as the evolutionary geneticist finding variants in DNA and correlating them to phenotypic differences, or observable differences, among the trees. Phenotypic traits that respond to climate include growth rate, water usage and biomass production over time, all of which are important details to know in order for this sugar pine restoration to be successful. 

“Sugar pine is one of the major species of both ecological and economic importance in the California forest ecosystem, but it is under threat due to an introduced pathogen,” said David Neale, a professor in the department of plant sciences and principal investigator on the project. 

This pathogen is commonly known as white pine blister rust, which travelled from Asia to Europe, and then to North America in 1925 via imported wood products. From there, it quickly spread to living forest populations.

“Often, trees that adapt to a pathogen have a trade-off with their ability to adapt to their climate or environment,” Eckert said. 

The goal is to increase genetic resilience and survivability in these trees, which becomes difficult when being resilient to drought could possibly increase sugar pine’s susceptibility to pathogens like white pine blister rust. 

“Survivors do matter because […] what we’re seeing is natural selection playing out currently,” Maloney said. 

Sugar pine is not the only tree affected by the Californian drought, nor is it the only one threatened by white pine blister rust. The whitebark pine, a high elevation pine listed as an endangered species by the Canadian government, is under threat from the same pathogen. Losing the tree species would create a severe ecological imbalance, as whitebark pine is an important food source for countless native species ranging from birds to bears. 

While research on the sugar pine tree is not directly applicable to species related to it, Eckert mentioned that research on other pines will require similar techniques and technology. Due to genetic markers being present in the same locations in the DNA, trees like whitebark pine will be easier to study in the wake of this project. 

Even with all of this genetic information, reforestation and restoration remain a challenging project to work on. 

“There’s a lot of debate about what sort of seed sources to use for restoration and reforestation,” Maloney said. “There are folks who think that you should be replanting maybe with different species but I counter that and I still think the best seed sources to use for restoration and reforestation are local seed sources.”

The use of local seed sources could be necessary to maintain ecological balance, because the project unearthed how well certain populations of trees have adapted to certain areas. In turn, local populations become phenotypically different from trees of the same species in other regions. 

“[This discovery] will impact basic research by allowing us to think more about the spatial scale of adaptation as a function of the environment,” Eckert said. “For research, it upends the assumption that adaptation happens in a range-wide, latitudinal scale.”

This highly localised adaptation supports Maloney’s assertion against planting foreign species of pine in the Lake Tahoe basin. The replanted species must be capable of not just surviving, but also thriving in their given environment. Neale speaks of the forest restoration project as a way to indirectly combat wildfires in California. Healthier trees means less fuel for the fires as well as the reduced chance of the fires even starting.

Sugar pine restoration is a multi-faceted project with the opportunity to make a great impact not only on conservation efforts but on research as well. 

“This project not only fosters restorative growth in California’s forests, it also plants seeds of forestry awareness and experience in our Corpsmembers that can lead them to careers in forest conservation,” said Bruce Saito, the director of the California Conservation Corps, via email.

Written by: HUSN KHARABANDA — hkhara@ucdavis.edu

Food waste more complex, interconnected than commonly known

Researchers at UC Davis have created a comprehensive report on food waste and loss to identify and provide solutions for the systemic inefficiencies currently in the food supply system that have resulted in the waste or loss of one third of global food. 

“We wanted to look at all aspects of food waste, from the farming end to the consumers and the systemic causes of food waste,” said Ned Spang, an assistant professor in the UC Davis Department of Food Science and Technology. 

The study, led by Spang, involved experts in fields ranging from food science to public health, highlighting the complexity of food and the loss of waste of it. This wide range of expertise allowed them to create an expansive and inclusive report that looked at food waste, the loss of products that are still usable due to avoidable reasons and loss, product that is trashed due to unavoidable reasons, from start to finish. 

Food waste and loss begins at the farm. The first losses are due to often unavoidable causes such as disease and insects that infect and ruin the crop. When it is time to harvest, more waste can be created. 

The United States Department of Agriculture grade system that defines the standards for food sold in commercial markets is effective at keeping food that is not safe for human consumption, due to potential disease and other ailments, from entering distribution. Farmers in search of the highest profit will want to grow food that is at the highest grade but the system is often restrictive due to its heavy focus on cosmetics. 

“Farmers will leave perfectly good produce in the field because it is not worth it to harvest it,” said Elizabeth Mitcham, director of the Postharvest Technology Center and the Horticulture Innovation Lab. 

A lower grade given to a farmer’s crop due to its “undesirable” appearances based on odd shape and color development causes farmers to leave good produce on the field. This is because the cost of harvesting it will not match or exceed the profits they would receive from selling “lower grade” produce. These highly selective standards that demand unrealistic levels of perfection from produce result in high levels of waste at the farm level. 

Postharvest food waste can be linked to the transportation and the storage of food. In a more industrialized and developed country such as the U.S., less food is wasted during this period.

“Developed countries have more infrastructure which includes good roads and refrigerators, and in less developed countries we tend to see higher level of losses due to less infrastructure,” Spang said.

The lack of infrastructure in less developed countries results in larger amounts of food waste as they do not have the technology available to extend the life of produce postharvest. In developed countries, an estimated 20% of food is wasted due to inadequate drying, storage, and transportation while in less developed countries 30% of food is wasted.

Once food reaches the market, consumer habits become the main source of food waste. Consumers enter a grocery store in search of the best produce, which is often based solely off appearances, and leave the less attractive produce to waste. Once the produce leaves the store, a high proportion of it ends up getting wasted in the consumer’s household.

In developed countries, a lower percentage of income is spent on food which results in food having a lower importance; not spending a large portion of one’s money on food helps create the perception that it is disposable and thus less valuable. Developed countries also tend to have more access to an overabundance of food, further instilling a societal acceptance of household food waste and valuing food less.

“Consumers have such an access to food, the waste is quite high,” said Irwin Donis-González, an assistant professor of biological and agricultural engineering. “In other countries where food is not as available, they tend to view it more importantly.” 

The cultural relationship with food in less developed countries highlights a key difference in the type of consumer waste seen around the world. Wealthier countries are less conscious of their private food waste because they can simply go buy more food. This mindset does not exist in places where food is harder to obtain. 

The complexity of food waste and loss is evident when attempting to analyze each realm of the food system. From the farm to consumers’ fridges, food waste is interconnected and coming up with solutions is just as complex.

Researchers at UC Davis work diligently to find solutions to the unsustainability of the food system at various parts in the cycle. Sara Pace, a postdoctoral scholar in the Spang Lab, is designing a new project that would address the impact of food waste going to landfills. When organic matter is thrown into landfill, due to the lack of oxygen, it undergoes anaerobic decomposition which produces methane, a very potent greenhouse gas. Because greenhouse gases contribute greatly to climate change, this project understands the importance of mitigating food waste.

The project uses anaerobic digestion infrastructure to treat food waste. Anaerobic digestion takes advantage of the methane naturally produced by the decomposition of food waste and harvests it to be used as a source of energy. The goal of this project is to install small systems close to processing plants and other main sources of food waste in urban environments to reduce greenhouse gas emissions and generate a source of renewable energy. 

“We are installing these systems close to the source or at the source so you can treat anything that is coming out and reduce them from going to the landfill,” Pace said.

The project will take food waste from processing plants and local restaurants and use it to produce heat or electricity through the capturing of released methane. Additionally, the process will produce a nutrient rich fertilizer that can be sold. If successful, this would be an efficient way to reduce food waste in urban settings while producing a form of energy.

At UC Davis, students are donating their time and energy to address food waste. The Food Recovery Network is a student run organization that collaborates with the on-campus dining commons and the Davis farmer’s market to reduce food waste.

“Our main goal is to reduce as much food waste as we can on campus and use that food to fight food insecurity,” said Alicia Marzolf, a third-year clinical nutrition major and the club’s event coordinator.

Since its creation in 2013, the Food Recovery Network has been able to divert 72,000 pounds of food from going to a landfill. Even at at student campus level, UC Davis is making it clear how important reducing food waste is. 

With a growing population, the need to address food waste is mounting. Globally, if we were able to reduce not only the amount of food being wasted but also reduce the amount of resources being wasted, we could increase the food produced by being more effective. 

“With an increasing population, we will need to use more land for agriculture and convert more land to farming,” Spang said. “Yet if we just start to reduce the inefficiencies within our current food system, we can increase yield as less will be wasted.” 

Reducing food waste has the capacity to help combat the ever rising global population. To be effective in our reductions, education and increased awareness of this issue are crucial. Changes started at an individual and local level have the capacity to be effective as people are inspired by their surroundings and motivated to do their part to reduce waste. 

Written by: Alma Meckler-Pacheco — science@theaggie.org