OREGON STATE UNIVERSITY

college of agricultural sciences

Toxic algal blooms behind Klamath River dams create health risks far downstream

CORVALLIS, Ore. – A new study has found that toxic algal blooms in reservoirs on the Klamath River can travel more than 180 miles downriver in a few days, survive passage through hydroelectric turbines and create unsafe water conditions on lower parts of the river in northern California.

Water-borne algal blooms can accumulate to concentrations that can pose health risks to people, pets and wildlife, and improved monitoring and public health outreach is needed to address this issue, researchers said.

The frequency, duration and magnitude of harmful algal blooms appear to be increasing.

The findings were made by researchers from Oregon State University, based on data from an extensive survey of the Klamath River in 2012, and just published in Harmful Algae, a professional journal.

The toxins may be a special concern if they are bioaccumulated in some animal species, such as freshwater mussels in which the level of the toxin can be more than 100 times higher than ambient concentrations.

“It’s clear that these harmful algal blooms can travel long distances on the river, delivering toxins to areas that are presently underappreciated, such as coastal margins,” said Timothy Otten, an OSU postdoctoral scholar in the OSU College of Science and College of Agricultural Sciences.

“And the blooms are dynamic, since they can move up and down in the water column and are physically distributed throughout the reservoir,” he said. “This means you can’t just measure water in one place and at one time and adequately estimate the public health risk.”

Microcystis is a seasonal blue-green cyanobacterium found around the world, preferring warm waters in lakes and reservoirs. Some strains are toxic, others are not. Its magnitude and persistence may increase with global climate change, researchers say, and it can cause a range of health issues, including liver damage, rashes, gastrointestinal illness, and other concerns. The toxin is not destroyed by boiling, making it unique from many other biological drinking water contaminants.

Improved awareness of the ability of blooms to travel significant distances downstream, and communication based on that, would help better inform the public, the OSU scientists said. But individual knowledge and awareness would also help.

“On a lake or river, if you see a green band along the shore or green scum on the surface, the water may not be safe to recreate in,” Otten said. “Because this problem is so diffuse, it's often not possible to put up posters or signs everywhere that there’s a problem in real-time, so people need to learn what to watch for.  Just as with poison ivy or oak, the general public needs to learn to recognize what these hazards look like, and know to avoid them in order to safeguard their own health.”

In this and other recent research, the OSU scientists have also developed genetic tools that can help identify problems with Microcystis, more quickly and at lower cost than some older methods. But those tools have not yet been widely adopted by the monitoring community.

“Right now, some lakes are not sampled at all for algal blooms, so we don’t really know if there’s a problem or not,” said Theo Dreher, the Pernot Professor and former chair of the Department of Microbiology in the OSU College of Science and College of Agricultural Sciences. “There’s no doubt we could use improved monitoring in highly used lakes and reservoirs, or in rivers downstream of them when toxic blooms are found.”

In this study, researchers found that intensive blooms of Microcystis in Iron Gate Reservoir on the Klamath River were the primary source of toxic algae observed downstream. They used genetic tracking technology to establish what many may have suspected when observing Microcystis in the lower reaches of the Klamath River. This transport of algae has been very little studied, even though it’s likely common.

The possible removal of dams on the Klamath River after 2020 may ultimately help mitigate this problem, the researchers said. Their study found no evidence of endemic Microcystis populations in the flowing regions of the Klamath River, both upstream and downstream of the Copco and Iron Gate reservoirs.

The problem with these bacteria is national and global in scope, especially in summer.

There are more than 123,000 lakes greater than 10 acres in size across the United States, and based on an EPA National Lakes Assessment, at least one-third may contain toxin-producing cyanobacteria. Dams, rising temperatures and atmospheric carbon dioxide concentrations, extreme weather and increased runoff of nutrients from urban and agricultural lands are all compounding the problem.

Many large, eutrophic lakes such as Lake Erie are plagued each year by algal blooms so massive that they are visible from outer space. Dogs have died from drinking contaminated water, and sea otter deaths in Monterey Bay have been attributed to eating shellfish contaminated with toxin produced by Microsystis.

This study was supported by Pacificorp, the OSU Agricultural Experiment Station and the Mabel E. Pernot Trust.

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Tim Otten, 541-737-1796

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Toxic algal bloom
Toxic algal bloom

Decades of research yield natural dairy thickener with probiotic potential

CORVALLIS, Ore. – Microbiologists at Oregon State University have discovered and helped patent and commercialize a new type of dairy or food thickener, which may add probiotic characteristics to the products in which it’s used.

The thickener is now in commercial use, and OSU officials say it may have a significant impact in major industries. The global market for polymers such as this approaches $7 billion, and there are estimates the U.S. spends up to $120 billion a year on probiotic products such as yogurt, sour cream and buttermilk.

The new product is produced by a natural bacterium that was isolated in Oregon. It’s the result of decades of research, beginning in the early 1990s when a novel polymer with an ability to rapidly thicken milk was discovered by an OSU microbiologist. The polymer is known as Ropy 352 and produced by a non-disease-causing bacterium.

“This is one of many naturally occurring, non-disease-causing bacterial strains my research program isolated and studied for years,” said Janine Trempy, an OSU microbiologist. “We discovered that this bacterium had a brand-new, never-before reported grouping of genes that code for a unique polymer that naturally thickens milk. In basic research, we’ve also broadened our understanding of how and why non-disease-causing bacteria produce polymers.”

This polymer appears to give fermented foods a smooth, thick, creamy property, and may initially find uses in sour cream, yogurt, kefir, buttermilk, cream cheese and artisan soft cheeses. Composed of natural compounds, it offers a slightly sweet property and may improve the sensory characteristics of low-fat or no-fat foods. And unlike other polymers that are now commonly used as thickeners, it may add probiotic characteristics to foods, with associated health benefits.

“There are actually very few new, non-disease-causing bacterial strains that produce unique polymers with characteristics desirable and safe for food products,” Trempy said. “In the case of a dairy thickener, for instance, a bacterium such as Ropy 352 ferments the sugar in the milk and produces a substance that changes the milk’s properties.”

These are chemical processes driven by naturally occurring bacteria that do not cause disease in humans, Trempy said, but instead may contribute to human health through their probiotic potential.

One of the most common polymers, xanthum gum, has been in use since 1969 and is found in a huge range of food products, from canned foods to ice cream, pharmaceuticals and beauty products. Xanthum gum is “generally recognized as safe” by the FDA, but is derived from a bacterium known to be a plant pathogen and suspected of causing digestive distress or being “pyrogenic,” or fever-inducing.

Trempy’s research program has determined the new polymer will thicken whole and non-fat milk, lactose-free milk, coconut milk, rice milk, and other products designed for use in either dieting or gaining weight. Beyond that, the polymer may have a wide range of applications such as thickening of pharmaceuticals, nutraceuticals, fruit juices, cosmetics and personal care products.

In their broader uses, microbial polymers are used for food production, chemical production, detergents, cosmetics, paints, pesticides, fertilizers, film formers, lubricants, explosives, pharmaceutical production and waste treatment.

OSU recently agreed to a non-exclusive license for the patented Ropy 352 technology to a global market leader for dairy starter cultures. It’s also available for further licensing through OSU’s Office of Commercialization and Corporate Development.

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Janine Trempy, 541-737-4441

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Food thickener
Dairy thickener

Study finds shade, cover can reduce predation by birds on trout

CORVALLIS, Ore. – As snowpack levels decline with the warming climate, many streams will experience less water flow, especially during summer months, potentially exposing more fish to predation by birds and other animals.

A new study has found that providing adequate shade and cover in small streams may reduce predation on trout by as much as 12 percent, from just one species of bird – the kingfisher. The findings, based on a study at the Oregon Hatchery Research Center in the Alsea River basin, are being published in the journal Ecology of Freshwater Fish.

Lead author Brooke Penaluna, who is a research fish biologist with the U.S. Forest Service’s Pacific Northwest Research Station in Corvallis, said the findings may give fisheries managers a new tool to help mitigate the effects of climate change and better preserve fish populations during low-water regimes.

“We’re able to tell fisheries managers that they may be able to increase their trout population by 12 percent – and it may be higher,” said Penaluna, who led the research as a doctoral student in the Department of Fisheries and Wildlife at Oregon State University. “It is possible that adding shade and cover to small streams may help protect trout against other predators as well.”

Avian predation of fish is hard to quantify in the wild because it is difficult to monitor and researchers don’t know how many fish are in a particular section of a stream. So Penaluna and her colleagues set up a study at the Oregon Hatchery Research Center where they could control the number of fish in a section of stream, monitor predation, and control the amount of cover available.

Using coastal cutthroat trout, they found that individual fish sought cover at least as large as their own bodies, and the addition of in-stream cover reduced the rate of predation from kingfishers by 12 percent. Trout also had better survival in areas with greater shade.

“It is generally assumed that shade is good for fish solely because of temperature,” said Jason Dunham, an aquatic ecologist with the U.S. Geological Survey and co-author on the study. “This study shows shade can make it more difficult for kingfishers to spot and catch fish. Kingfishers are the number one predators of small trout.”

“Eighty percent of the streams in the U.S. are the same size or smaller than those studied at the hatchery,” added Dunham, a courtesy faculty member in OSU’s Department of Fisheries and Wildlife. “This study provides important information for streams that could be among the first affected by climate change.”

Cover is particularly important during late summer months when water levels are naturally low and deep pools are hard to find, the researchers say. Adding wood or rocks to streams for cover may help protect cutthroat trout and other fish at a low cost.

“The beauty of this study is in its simplicity,” said David Noakes, an OSU professor of fisheries and wildlife and director of the Oregon Hatchery Research Center. “We wanted to know the impact of shade and cover on fish, and Brooke was able to find that out. It is a very useful piece of knowledge.”

The study was funded by multiple sources. The Oregon Hatchery Research Center is a collaboration between the Oregon Department of Fish and Wildlife and OSU’s Department of Fisheries and Wildlife.

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Brooke Penaluna, 541-758-8783, bepenaluna@fs.fed.us; David Noakes, 541-737-1953, david.noakes@oregonstate.edu; Jason Dunham, 541-750-7397, jdunham@usgs.gov

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Trout

Solomon Islands dolphin hunts cast spotlight on small cetacean survival

NEWPORT, Ore. – A new study on the impact of ‘drive-hunting’ dolphins in the Solomon Islands is casting a spotlight on the increasing vulnerability of small cetaceans around the world.

From 1976 to 2013, more than 15,000 dolphins were killed by villagers in Fanalei alone, where a single dolphin tooth can fetch the equivalent of 70 cents ($0.70 U.S.) – an increase in value of five times just in the last decade.

Results of the Solomon Islands study are being reported this week online in the new journal, Royal Society Open Science.

“In the Solomon Islands, the hunting is as much about culture as economic value,” said Scott Baker, associate director of the Marine Mammal Institute at Oregon State University and co-author on the study. “In other parts of the world, however, the targeting of dolphins and other small cetaceans appears to be increasing as coastal fishing stocks decline.

“The hunting of large whales is managed by the International Whaling Commission,” added Baker, who works out of OSU’s Hatfield Marine Science Center in Newport, Ore. “But there is no international or inter-governmental organization to set quotas or provide management advice for hunting small cetaceans. Unregulated and often undocumented exploitation pose a real threat to the survival of local populations in some regions of the world.”

The drive-hunting of dolphins has a long history in the Solomon Islands, particularly at the island of Malaita, according to Marc Oremus, a biologist with the South Pacific Whale Research Consortium and lead author on the study. In 2010, the most active village, Fanalei, suspended hunting in exchange for financial compensation from an international non-governmental organization. The villagers resumed hunting in 2013.

“After the agreement broke down in 2013, a local newspaper reported that villagers had killed hundreds of dolphins in just a few months,” Oremus said. “So we went to take a look.”

Oremus and co-author John Leqata, a research officer with the Ministry of Fisheries and Marine Resources, visited Fanalei in March of 2013 to document the impact on the population, and examine detailed records of the kills. During the first three months of that year, villagers killed more than 1,500 spotted dolphins, 159 spinner dolphins, and 15 bottlenose dolphins.

This is one of the largest documented hunts of dolphins in the world, rivaling even the more-industrialized hunting of dolphins in Japan, noted Baker, whose genetic identification research was featured in the Academy Award-winning documentary on dolphin exploitation, “The Cove.”

“It is also troubling that teeth are increasing in cash value, apparently creating a commercial incentive for hunting dolphins,” Baker said.

In drive-hunting, the hunters operate in close coordination from 20 to 30 traditional canoes. When dolphins are found, the hunters used rounded stones to create a clapping sound underwater. The hunters maneuver the canoes into a U-shape around the dolphins, using sound as an acoustic barrier to drive them toward shore where they are killed.

“The main objective of the hunt is to obtain dolphin teeth that are used in wedding ceremonies,” Oremus said. “The teeth and meat are also sold for cash.”

Oremus said the Solomon Island hunters understand the risk of exploiting the population.

“The government of the Solomon Islands has contributed substantially to research in recent years, but is not well-equipped to undertake the scale of research needed to estimate abundance and trends of the local dolphin population,” Oremus said. “This problem exists in many island nations with large ‘Exclusive Economic Zones.’”

The research was supported by the International Fund for Animal Welfare, the Pew Environmental Group and the International Whaling Commission.

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Scott Baker, 541-272-0560, scott.baker@oregonstate.edu

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dolphinteeth

Dolphin teeth are sold for necklaces

Longest mammal migration raises questions about distinct species

NEWPORT, Ore. – A team of scientists from the United States and Russia has documented the longest migration of a mammal ever recorded – a round-trip trek of nearly 14,000 miles by a whale identified as a critically endangered species that raises questions about its status.

The researchers used satellite-monitored tags to track three western North Pacific gray whales from their primary feeding ground off Russia’s Sakhalin Island across the Pacific Ocean and down the West Coast of the United States to Baja, Mexico. One of the tagged whales, dubbed Varvara (which is Russian for Barbara), visited the three major breeding areas for eastern gray whales, which are found off North America and are not endangered.

Results of their study are being published this week by the Royal Society in the journal Biology Letters.

“The fact that endangered western gray whales have such a long range and interact with eastern gray whales was a surprise and leaves a lot of questions up in the air,” said Bruce Mate, director of the Marine Mammal Institute at Oregon State University and lead author on the study. “Past studies have indicated genetic differentiation between the species, but this suggests we may need to take a closer look.”

Western gray whales were thought to have gone extinct by the 1970s before a small aggregation was discovered in Russia off Sakhalin Island – with a present estimated population of 150 individuals that has been monitored by scientists from Russia and the U.S. since the 1990s.

Like their western cousins, eastern gray whales were decimated by whaling and listed as endangered, but conservation efforts led to their recovery. They were delisted in 1996 and today have a population estimated at more than 18,000 animals.

Not all scientists believe that western gray whales are a separate, distinct species. Valentin Ilyashenko of the A.N Severtsov Institute for Ecology and Evolution, who is the Russian representative to the International Whaling Commission, has proposed since 2009 that recent western and eastern gray whale populations are not isolated and that the gray whales found in Russian waters are a part of an eastern population that is restoring its former historical range. He is a co-author on the study.

“The ability of the whales to navigate across open water over tremendously long distances is impressive and suggests that some western gray whales might actually be eastern grays,” Mate said. “But that doesn’t mean that there may not be some true western gray whales remaining.

“If so, then the number of true western gray whales is even smaller than we previously thought.”

Since the discovery that western and eastern gray whales interact, other researchers have compared photo catalogues of both groups and identified dozens of western gray whales from Russia matching whale photographs taken in British Columbia and San Ignacio Lagoon in Baja California, Mexico.

Protecting the endangered western gray whales has been difficult – five whales have died in Japanese fishing nets within the last decade. Their feeding areas off Japan and Russia include fishing areas, shipping lanes, and oil and gas production – as well as future sites oil sites. Their largely unknown migration routes may include additional hazards.

The study was coordinated by the International Whaling Commission, with funding provided by Exxon Neftegas Limited, the Sakhalin Energy Investment Company, the U.S. Office of Naval Research, and OSU’s Marine Mammal Institute.

Media Contact: 
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 Bruce Mate, 541-867-0202, bruce.mate@oregonstate.edu; Ladd Irvine, 541-867-0394, ladd.irvine@oregonstate.edu

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Western Gray Whale - Sakhalin Island, Russia

 

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Photos by Craig Hayslip, OSU Marine Mammal Institute

Mechanism outlined by which inadequate vitamin E can cause brain damage

 

The study this story is based on is available online: http://bit.ly/1DtAIyU

 

CORVALLIS, Ore. – Researchers at Oregon State University have discovered how vitamin E deficiency may cause neurological damage by interrupting a supply line of specific nutrients and robbing the brain of the “building blocks” it needs to maintain neuronal health.

The findings – in work done with zebrafish – were just published in the Journal of Lipid Research. The work was supported by the National Institutes of Health.

The research showed that zebrafish fed a diet deficient in vitamin E throughout their life had about 30 percent lower levels of DHA-PC, which is a part of the cellular membrane in every brain cell, or neuron. Other recent studies have also concluded that low levels of DHA-PC in the blood plasma of humans are a biomarker than can predict a higher risk of Alzheimer’s disease.

Just as important, the new research studied the level of compounds called “lyso PLs,” which are nutrients needed for getting DHA into the brain, and serve as building blocks that aid in membrane repair. It showed the lyso PLs are an average of 60 percent lower in fish with a vitamin E deficient diet.

The year-old zebrafish used in this study, and the deficient levels of vitamin E they were given, are equivalent to humans eating a low vitamin E diet for a lifetime. In the United States, 96 percent of adult women and 90 percent of men do not receive adequate levels of vitamin E in their diet.

DHA is a polyunsaturated fatty acid, or PUFA, increasingly recognized as one of the most important nutrients found in omega-3 fatty acids, such as those provided by fish oils and some other foods.

“This research showed that vitamin E is needed to prevent a dramatic loss of a critically important molecule in the brain, and helps explain why vitamin E is needed for brain health,” said Maret Traber, the Helen P. Rumbel Professor for Micronutrient Research in the College of Public Health and Human Sciences at OSU and lead author on this research.

“Human brains are very enriched in DHA but they can’t make it,” said Traber, who also is a principal investigator in the Linus Pauling Institute at OSU. “They get it from the liver. The particular molecules that help carry it there are these lyso PLs, and the amount of those compounds is being greatly reduced when vitamin E intake is insufficient. This sets the stage for cellular membrane damage and neuronal death.”

DHA is the needed nutrient, Traber said, but it’s lyso PLs which help get it into the brain. It’s the building block.

“You can’t build a house without the necessary materials,” Traber said. “In a sense, if vitamin E is inadequate, we’re cutting by more than half the amount of materials with which we can build and maintain the brain.”

Some other research, Traber said, has shown that the progression of Alzheimer’s disease can be slowed by increased intake of vitamin E, including one study published last year in the Journal of the American Medical Association. But that disease is probably a reflection of years of neurological damage that has already been done, she said. The zebrafish diet used in this study was deficient in vitamin E for the whole life of the fish – as is vitamin E deficiency in some humans.

Vitamin E in human diets is most often provided by dietary oils, such as olive oil. But many of the highest levels are in foods not routinely considered dietary staples – almonds, sunflower seeds or avocados.

“There’s increasingly clear evidence that vitamin E is associated with brain protection, and now we’re starting to better understand some of the underlying mechanisms,” Traber said.

Other collaborators on this research included Jan Stevens from the OSU College of Pharmacy and Robert Tanguay from the College of Agricultural Sciences.

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Maret Traber, 541-737-7977

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Sunflowers
Vitamin E source

Fish native to Japan found in Port Orford waters

NEWPORT, Ore. – A team of scientists from Oregon State University and the Oregon Department of Fish and Wildlife is studying an unusual fish captured alive in a crab pot near Port Orford this week called a striped knifejaw that is native to Japan, as well as China and Korea.

The appearance in Oregon waters of the fish (Oplegnathus fasciatus), which is sometimes called a barred knifejaw or striped beakfish, may or may not be related to the Japanese tsunami of 2011, the researchers say, and it is premature to conclude that this non-native species may be established in Oregon waters.

But its appearance and survival certainly raises questions, according to OSU’s John Chapman, an aquatic invasive species specialist at the university’s Hatfield Marine Science Center in Newport.

“Some association with Japanese tsunami debris is a strong possibility, but we cannot rule out other options, such as the fish being carried over in ballast water of a ship or an aquarium fish being released locally,” Chapman said. “But finding a second knifejaw nearly two years after the discovery of fish in a drifting Japanese boat certainly gets my attention.”

In March 2013, five striped knifejaws were found alive in a boat near Long Beach, Washington, that had drifted over from Japan. Four of the fish were euthanized, but one was taken to the Seaside Aquarium, where it is still alive and well.

OSU marine ecologist Jessica Miller examined the four euthanized knifejaws from Washington in 2013, analyzing their otoliths, or ear bones, for clues to their origin.

“The young fish of these species are known to associate with drift and may be attracted to floating marine debris,” Miller said. “Japanese tsunami marine debris continues to arrive on beaches in Oregon and Washington – and some debris from Japan washed up on the southern Oregon coast this month – so it is not inconceivable that the Port Orford fish was associated with Japanese marine debris.

“The species is also found in other parts of Asia and the northwest Hawaiian islands, so it is native to a broader range than just Japan,” she added. “At this time, there is no evidence that they are successfully reproducing in Oregon.”

Tom Calvanese, an Oregon State graduate student researcher working with Oregon Sea Grant on the start-up of a new OSU field station in Port Orford, worked with the fisherman to secure the exotic species. The fish is approximately 13 centimeters in length, and thus not a fully grown adult, and was captured in a crab pot between Port Orford and Cape Blanco  - just off the Elk River in southern Oregon.

“We are fortunate to have this occur in a fishing community that is ocean-aware,” Calvanese said. “The fisherman who caught the fish identified it as an exotic then transported it to shore alive, where the fish buyer was able to care for it. It was then brought to my attention, initiating a response from the scientific community that will result in an exciting learning opportunity for all.

“It appears to be in good shape and was swimming upright, though it had a small cut in its abdomen,” Calvanese said. “I talked to Keith Chandler at the Seaside Aquarium who suggested feeding it razor clams, which it took readily.”

Steven Rumrill, a biologist with the Oregon Department of Fish and Wildlife, is working with Calvanese and others to transport the fish to a quarantine facility at the Hatfield Marine Science Center, where it will be under the care of OSU aquatic veterinarian Tim Miller-Morgan of Oregon Sea Grant.

“It is important that the fish be held in quarantine until the wound is healed and for sufficient time to ensure that it is free from any pathogens or parasites that could pose a threat to our native fishes,” Rumrill said.

Sam Chan, an OSU invasive species expert affiliated with Oregon Sea Grant and vice-chair of the Oregon Invasive Species Council, has seen striped knifejaws in Japan and estimates this fish may be 1-2 years old.

“Therefore, it is unlikely to have left Japan in the 2011 tsunami,” Chan said, “but a boat could have been milling around Asian waters for the past 2-3 years and then picked up the fish and ridden the currents over. The big question is – are there more of these?”

Chan said Oregon Sea Grant – an OSU-based marine research, education and outreach program – would work with Oregon fishermen, crabbers and others to keep a lookout for additional striped knifejaws and other exotic species.

Calvanese posted a brief video of the fish on you-tube: http://youtu.be/XzA4NPXTYqg

Oregonians who believe they have spotted an invasive species are encouraged to report it at http://oregoninvasiveshotline.org, or call 1-866-INVADER.

Media Contact: 
Source: 

John Chapman, 541-961-3258, john.chapman@oregonstate.edu;

Jessica Miller, 541-867-0381, Jessica.miller@oregonstate.edu;

Tom Calvanese, 415-309-6568, tom.calvanese@oregonstate.edu;

Sam Chan, 503-679-4828, sam.chan@oregonstate.edu;

Steven Rumrill, 541-867-0300, ext. 245; Steven.S.Rumrill@state.or.us

Climate change may affect tick life cycles, Lyme disease

CORVALLIS, Ore. – A new study suggests that changing climate patterns may be altering the life cycles of blacklegged ticks in the northeastern United States, which could increase transmission among animals – and ultimately humans – of certain pathogens, including the bacterium that causes Lyme disease.

Other colder regions of the country that have sufficient populations of blacklegged ticks – particularly Wisconsin and Minnesota – may also experience a higher risk of Lyme disease. However, the changing life cycles of the ticks may result in a less-likely probability of transmitting a more deadly pathogen that results in Powassan encephalitis, the researchers say.

Results of the research are being published this week in a special issue of Philosophical Transactions of the Royal Society B dedicated to climate change and vector-borne diseases.

A team of scientists led by Taal Levi of Oregon State University and Richard Ostfeld of the Cary Institute of Ecosystem Studies analyzed 19 years of data on blacklegged ticks in the Northeast and their relationship to “host” animals ranging from small rodents to deer and other larger mammals. They then overlaid the results with climate data and used computer models to predict what may happen in the future.

“The bottom line is that as the climate warms, it is pushing the timing of tick nymphs and larvae forward, potentially changing the interactions they have with their hosts,” said Levi, an assistant professor in OSU’s Department of Fisheries and Wildlife in the College of Agricultural Sciences and lead author on the study.

“October is a key month,” he added, “because the difference between a cold fall and a warmer fall can have a profound effect on when the ticks interact with their hosts.”

Blacklegged ticks can be found in hardwood forests all along the eastern seaboard as well as in the northern states. They have a two-year life cycle that goes from eggs, to larva, to nymphs to adults.

After adult ticks lay eggs in the spring, the larvae emerge in the summer and in August and September they begin looking for a host to feed upon – usually mice, voles and other small rodents. They are not born infected with pathogens, but can become infected after feeding upon an infected host. However, their feeding lasts only a few days and they then become inactive and thus are not a threat to humans or large mammals at this stage.

As they transform to nymphs, they become active the following spring when they begin looking for a host. If not previously infected as larva, they can become infected again by selecting a host carrying a pathogen. Studies have shown that as many as one out of four blacklegged tick nymphs carry the Lyme disease bacterium.

“This is where climate change comes in,” Levi said. “When nymphs emerge months before larvae, they inoculate the host community with pathogens that the later-emerging larvae can then contract. The Lyme disease pathogen is long-lived – it will remain in the host. So an increasing gap between the nymphs feeding in the spring and the next cohort of larvae feeding in late summer will give the nymphs more time to infect the hosts with bacterium that can then be passed to the next generation of tick larvae.”

Since ticks can’t fly or jump, they usually find hosts by hanging onto the ends of grass blades or small branches and attaching themselves to animals. This hit-or-miss approach results in some tick larvae that don’t find a host. And if the weather is cold and activity ceases early, the number of larva that “over-winter” increases.

When that happens, the larva and nymphs are more likely to feed at the same time, the researchers say, and that may increase the chance of transmitting the pathogen causing Powassan encephalitis, which can be deadly but is very short-lived in hosts. The disease causes mortality in about 10 percent of human patients, and persistent illness in another 50 percent.

“Luckily the pathogen for Powassan doesn’t persist for very long, but having synchronous activity between larva and nymphs makes transmission more likely,” Levi said. “If autumn temperatures increase, it looks like fewer larvae will overwinter to feed at the same time as nymphs, which should reduce the risk of Powassan virus.”

It is the nymph stage that is most problematic for humans, the researchers say. The larva usually target rodents, which are low to the ground and plentiful. Adult ticks can easily transmit the Lyme disease pathogen, but adult males do not feed and females usually target deer and other woodland creatures. Also, it takes three days for Lyme disease to establish after a tick bite and most people will spot and remove the tick within that time.

Powassan transmission, however, is almost immediate – hence the concern for colder climate states.

Blacklegged ticks also inhabit the western United States, though in much fewer numbers. Tick transmission of Lyme disease has grown rapidly in the Northeast, however, with estimates of 200,000 cases per year in New York alone.

The study was supported by the National Science Foundation, National Institutes of Health, Environmental Protection Agency and Dutchess County, N.Y. Other researchers on the study include Felicia Keesing of Bard College; and Kelly Oggenfuss and Richard Ostfeld of the Cary Institute of Ecosystem Studies in Millbrook, N.Y.

Media Contact: 
Source: 

Taal Levi, 541-737-4067, taal.levi@oregonstate.edu

Study finds lamprey decline continues with loss of habitat in Oregon

CORVALLIS, Ore. – A new study aimed at understanding habitat needs for Pacific lamprey in western Oregon found this once-abundant fish that is both ecologically and culturally significant prefers side channels and other lower water velocity habitats in streams.

However, because of the legacy of historic land uses in the Northwest – including human settlement and activities – these habitats are much less common than they were in the past. And that may explain why populations of lamprey have declined over the past several decades – not only in western Oregon, but throughout the Pacific Northwest.

Results of the study were just published in the Ecology of Freshwater Fish.

“The lamprey decline has probably been going on for the past half century, but it wasn’t until the last 15-20 years that it has been recognized by many in the scientific community,” said Luke Schultz, a research assistant in Oregon State University’s Department of Fisheries and Wildlife and lead author on the study. “Today lamprey populations are at about 5 to 10 percent of the 1960s totals at Bonneville Dam, and the story is much the same elsewhere.

“The Willamette River basin is one of the few places that still appears to have decent numbers of lamprey because of its system of sloughs and side channels,” he added. “But they are facing new threats, such as introduced fish species that prey on them – especially bass – so we’ll likely be hearing more about this emerging threat in the next few years.”

Schultz is project leader Oregon Cooperative Fish Research Unit’s Pacific lamprey project – a joint effort between OSU and the U.S. Geological Survey that is seeking to learn more about the fish and restore its habitat. Although this latest article focuses on the Willamette Basin, Schultz and his colleagues at OSU, the USGS, Oregon Department of Fish and Wildlife and the U.S. Fish and Wildlife Service have looked at lamprey populations and habitat from the Columbia River in northeastern Oregon to southern Oregon’s Umpqua River.

The causes of Pacific lamprey decline are myriad, the researchers say. Restoring their numbers will require mitigation in the form of restoring habitat to include complex channels and deep pools, and the removal of barriers that block access to spawning grounds for adult lampreys, the authors note.

“Removal or mitigation will allow lampreys to recolonize those areas,” Schultz said.

Some factors affecting the lamprey decline may be out of the researchers’ control, Schultz said, specifically ocean conditions. They require an abundance of food; ocean conditions that are favorable to salmon are usually beneficial for lampreys, as well. Rather than swimming freely, they may attach themselves to large fishes, or even whales, sea lions or other marine animals – and the abundant ocean prey lets them grow large.

“Pacific lamprey may spend one or two years in the ocean,” Schultz noted. “They will weigh less than an ounce when they go out there as juveniles, and they may grow to 30 inches in length and up to two pounds before they return.”

Although Pacific lampreys are anadromous, another species, the brook lamprey, only grows to a length of 6-7 inches and stays in fresh water for its entire lifespan of 4-8 years.

It is the Pacific lamprey that researchers are focusing on because of their one-time abundance, larger size, and more prominent ecological role.

“These are really interesting animals that have historic importance in the Pacific Northwest,” Schultz noted. “They can live up to about 10 years or so – about three times longer than the coho salmon life cycle – and they are roughly six times as energy-dense as salmon, making them important prey.

“Because of that, I like to call them swimming sticks of butter.”

When lampreys are abundant, they reduce predation by a variety of species – especially sea lions, but also sturgeon, birds, bass and walleye – on juvenile salmon and steelhead. It may not be an accident that salmonid numbers have declined at the same time lamprey populations have diminished.

The research in the study has led to some habitat restoration work supported by the Columbia River Inter-Tribal Fish Commission. Helping lamprey populations recover has important social significance as well as ecological importance, Schultz said.

“Lampreys were an incredibly important resource for many Northwest tribes because they provided a source of protein in the summer months when salmon weren’t as readily available,” he noted. “Now the only place where there is even a limited tribal harvest is at Willamette Falls.”

More information on lampreys is available in this feature article in OSU’s Terra Magazine: http://bit.ly/1fhu8k4

Media Contact: 
Source: 

Luke Schultz, 541-737-1961; luke.schultz@oregonstate.edu

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Sampling at Willamette Falls

 

 

 

 

 



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Juvenile lamprey



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Measuring in the field

Study finds tropical fish moving into temperate waters

CORVALLIS, Ore. – Tropical herbivorous fish are beginning to expand their range into temperate waters – likely as a result of climate change – and a new international study documents the dramatic impact of the intrusion in the Mediterranean Sea.

Temperate waters are typically dominated by algal “forests” and have naturally low levels and limited diversity of herbivores, the researchers say. But as tropical fish move into these waters, they are consuming much of the plant life and changing the habitat as well as the manner in which different species interact.

Results of the study, which was funded primarily by the Pew Foundation, have just been published in the Journal of Ecology. It builds on a previous study documenting the move of tropical fish species into temperate waters that recently was published in Proceedings of the Royal Society B.

“The introduction of tropical fish into more temperate regions is troubling and this new study gives a vivid example of what can happen when non-native species occupy a new ecosystem,” said Fiona Tomas Nash, a courtesy professor of fisheries and wildlife at Oregon State University and a co-author on both studies.

“We now know that the arrival of tropical fish into temperate areas is occurring on an increasing basis around the world,” she added. “This is the first attempt to characterize what impacts these fish are having – and the mechanisms driving these impacts.”

In this latest study, an international research team surveyed roughly 1,000 kilometers of coastline in the eastern Mediterranean to study two species of tropical fish called rabbitfish. They were introduced to the region through the Suez Canal and now have become a dominant component of the total fish biomass in the southernmost part of the eastern Mediterranean.

This part of the Mediterranean has two distinct areas – one with warmer regions that attract abundant numbers of rabbitfish, and colder regions where they are very rare or completely absent. Where abundant, their damage has been striking: a 65 percent reduction in canopy algae, a 60 percent reduction in overall benthic biomass (algae and invertebrates) and a 40 percent decrease in the total number of plant and animal species.

“The fear is that if the colder regions warm just a bit through climate change or some other mechanism, rabbitfish will begin moving into those areas as well,” Tomas Nash said.

To learn more about how the rabbitfish changed the ecosystem, the researchers videotaped fish feeding in the Mediterranean off Turkey in two areas – one dominated by tropical rabbitfish and the other dominated by native temperate fish. They were surprised by what they found. Native temperate herbivorous fish actually had higher consumption rates than the tropical rabbitfish. “We did not expect to see that,” Tomas Nash said.

But while native fish targeted only adult macroalgae, the two species of rabbitfish fed complementarily – one targeted the mature kelps while the other fed almost exclusively on emerging algal “recruits,” or juvenile plants.

“The result is that one species denudes the forest and the other prevents it from recovering,” said Tomas Nash, who also has a faculty appointment with the Mediterranean Institute for Advanced Studies in Spain.

A study off Japan by collaborators found that the introduction of tropical species there, including rabbitfish and parrotfish, resulted in the loss of kelp forests and the emergence of non-native corals in as little as 20 years.

In the first paper, the researchers outlined how tropical herbivorous fish primarily along west boundary currents are moving into temperate zones, including South Africa, Brazil, the Gulf of Mexico, Australia and Japan, as well as the Mediterranean. Other areas, including the Pacific Northwest of the United States, have not seen sustained spread of tropical species likely due to prevailing currents and because surface waters are too cold due to seasonal upwelling.

The researchers found algal forests in the waters off Greece had not been severely affected because only the rabbitfish that feeds on adult algae is present and in relatively low densities. They have just begun studies of rabbitfish and chub arrivals in Australia.

“The greatest damage that we documented was off Turkey, which may be serving as the proverbial canary in the coal mine,” Tomas Nash said. “The barrenness of the underwater habitat is unique and quite striking – it is spread over hundreds of kilometers.”

Media Contact: 
Source: 

Fiona Tomas Nash, 541-737-4531; fiona.tomasnash@oregonstate.edu

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Cystos Adrasan 1

Healthy ecosystem

 

 

denuded landscape

Effects of non-native fish