Natural Resources and Environment
Natural Resources and Environment
News Article | May 12, 2017
Researchers Simo Laakkonen and Timo Vuorisalo from the University of Turku, Finland, together with their colleague Richard Tucker from the University of Michigan, USA, have edited the first extensive summary with global perspectives on the environmental history of the Second World War. The Long Shadows: A Global Environmental History of the Second World War was published by Oregon State University Press in April 2017. The Second World War was beyond comparison in scale. It was a human tragedy that claimed 50-70 million lives. In addition, the war left deep scars in nature in the war zones, the home front and areas used by the armament industry. - The Second World War contributed decisively to the birth of the current global environmental problems. On the other hand, it helped to raise concern over a possible apocalypse caused by humans, which also led to the activation of international environmental politics. This major war had a great impact on the development of both the modern environmental problems and the means to solve them during the Cold War era and later on. The war casts long shadows to this day, state Simo Laakkonen and Timo Vuorisalo. The book has its roots partly in an earlier work by Laakkonen and Vuorisalo on the ecology of war published in Finnish in 2007, and partly in an international symposium they organised in 2012. In addition to the themes familiar from the earlier book, the recent publication explores the effects of the war-supporting infrastructure at the Arctic region, Indian subcontinent and the Pacific Ocean. Furthermore, it discusses the consequences of the procurement of raw materials used in warfare in Canada, Japan, Mexico and Caribbean Sea region, and the food crises caused by the war in Africa, Soviet Union and China. Timo Vuorisalo is a University Lecturer of Environmental Sciences at the University of Turku, Finland, Simo Laakkonen is a University Lecturer of Landscape Studies at the University Consortium of Pori, Finland, and Richard Tucker is Adjunct Professor in the School of Natural Resources and Environment at the University of Michigan, the United States. Simo Laakkonen, Richard P. Tucker and Timo Vuorisalo (eds), The Long Shadows: A Global Environmental History of the Second World War (Corvallis: Oregon State University Press, 2017). http://osupress.
News Article | May 17, 2017
ANN ARBOR--A new study of native bumblebee populations in southeastern Michigan cities found, surprisingly, that Detroit has more of the large-bodied bees than some surrounding, less urbanized locations. The University of Michigan students who conducted the study suspect that the large amount of vacant or idle land in Detroit may boost the bumblebee population by providing nesting sites and flowers for food. Bumbleebees belong to the bee genus Bombus. In the study, more than 500 individuals from 10 species were identified at 30 sites in southeast Michigan. "Sites within Detroit had higher Bombus abundance and diversity, despite their location in the densest urban landscape," according to the authors--four U-M graduate students and one undergraduate--of a study published online May 17 in the journal Royal Society Open Science. "Overall, these results have important implications for conservation of native bee populations and pollination services." Native bees are critical sources of pollination for agriculture and wild flowering plants. Many native bees are declining in both abundance and diversity, due to various causes that likely include loss of habitat from human activities. While the effects of large-scale agriculture on native bees are relatively well understood, the effects of urban development are less clear. To help clarify the role of urbanization, the U-M researchers sampled bumblebees at nature reserves and urban farms and gardens in several southeast Michigan cities--Dexter, Ann Arbor, Ypsilanti, Dearborn and Detroit--with varying degrees of urban development. Each city has a dense urban core surrounded by suburban development. Bumblebees need to nest in less-disturbed areas with bare ground, tall grass or abandoned tree stumps, making them a good candidate for testing the effects of urban land development. Handheld nets and insect traps were used to capture the bees. The researchers used geographical information systems data to develop profiles of the land cover types surrounding each of the 30 study sites. As a proxy for urban development, they used the amount of impervious surfaces--buildings, concrete parking structures, asphalt roads, etc.--blanketing the ground. They found that increased urbanization, as measured by the proportion of impervious surface area, was tied to decreases in both the abundance and diversity of bumblebees sampled at sites outside Detroit. But that pattern did not hold in Detroit. There, high urbanization seemed to be correlated with increased bumblebee abundance when compared to less urbanized sites, a finding the authors describe as "an initially unintuitive trend." In fact, the Detroit site with the highest impervious surface coverage, an urban agriculture demonstration garden in downtown Detroit, had nearly the same number of bumblebees captured as U-M's E.S. George Reserve, a nature preserve near Pinckney with the lowest impervious surface cover proportion in the study. One possible explanation is that the thousands of vacant residential properties in Detroit help sustain bumblebee colonies, according to the authors. Vacant lots are often less frequently mowed and less likely to be treated with pesticides and herbicides. Therefore, these lots can provide various flowering plants and nesting sites for bees. The most abundant bumblebee species sampled during the study was the common eastern bumblebee (72.1 percent), followed by the brown-belted bumblebee (11.4 percent) and the two-spotted bumblebee (9.6 percent). Another unexpected study finding was that urbanization seems to affect female and male bumblebees differently. Those distinct and previously unidentified effects seem to stem from behavioral differences between sexes. Bumblebee colonies consist of one reproductive female, many female workers that forage for nectar and pollen and bring it back to the colony, and reproductive male drones whose only role is to mate. These different roles lead to distinct movement patterns and nesting needs between the sexes. By analyzing males and females separately, the U-M researchers found that observed declines in overall bumblebee abundance and diversity with increasing urbanization were entirely driven by declines in female workers, while male abundance and diversity were unrelated to urbanization. The student researchers said their results highlight the importance of heterogeneity in urban areas and suggest that urban landscapes can be managed to support native bee conservation. They thanked the farmers and gardeners who offered their plots for the study. "We are very grateful to everyone who participated. We could not have done this research without their support," said first author Paul Glaum. The authors of the Royal Society Open Science paper are graduate students Glaum, Chatura Vaidya and Gordon Fitch of the Department of Ecology and Evolutionary Biology; graduate student Maria-Carolina Simao of the School of Natural Resources and Environment; and undergraduate Benjamin Iulinao of the Department of Ecology and Evolutionary Biology. The work was partially supported by a U-M Mcubed grant and the Matthaei Botanical Garden & Nichols Arboretum Student Research Funds. Glaum was partially supported by the Graham Institute-Dow Sustainability Fellows Program. Iulinao was partially supported through the University of Michigan-Undergrad Research Opportunities Program.
News Article | May 22, 2017
The Ecological Society of America recognizes Michael J.M. McTavish and Julienne E. NeSmith for outstanding student research presentations at the 101st Annual Meeting of the Society in Fort Lauderdale, Florida in August 2016. ESA will present the awards during the 2017 Annual Meeting in Portland, Oregon. The awards ceremony will take place on Monday, August 7, at 8 AM in the Oregon Ballroom at the Oregon Convention Center. Murray F. Buell had a long and distinguished record of service and accomplishment in the Ecological Society of America. Among other things, he ascribed great importance to the participation of students in meetings and to excellence in the presentation of papers. To honor his selfless dedication to the younger generation of ecologists, the Murray F. Buell Award for Excellence in Ecology is given to a student for the outstanding oral paper presented at the ESA Annual Meeting. Lucy Braun, an eminent plant ecologist and one of the charter members of the Society, studied and mapped the deciduous forest regions of eastern North America and described them in her classic book, The Deciduous Forests of Eastern North America. To honor her, the E. Lucy Braun Award for Excellence in Ecology is given to a student for the outstanding poster presentation at the ESA Annual Meeting. Papers and posters are judged on the significance of ideas, creativity, quality of methodology, validity of conclusions drawn from results, and clarity of presentation. Award panel members honored Michael J.M. McTavish with the Buell Award for his presentation "Selective granivory of exotic earthworms within commercial grass seed mixes: Implications for seeding-based restoration in invaded ecosystems." McTavish is a doctoral candidate working with Professor Stephen D. Murphy in the School of Environment, Resources & Sustainability at the University of Waterloo in Ontario, Canada. The invasion of earthworms into previously earthworm-free soils is instigating sweeping change in the ecosystems of eastern North America. This has brought interest in the earthworms' appetite for seeds and how they may impact ecological restoration projects that add seeds to soil. McTavish investigated the characteristics of commercial grass seeds favored by the exotic earthworm Lumbricus terrestris. He observed how earthworm activity affected the biomass of different types of grass in outdoor, enclosed experiments called mesocosms, which simulate natural environments under controlled conditions. He found that earthworms preferred smaller seeds that had been coated to increase water uptake, resulting in decreased grass biomass in mesocosms planted with coated seeds. The judges felt that McTavish showed excellence in presenting and answering his experimental questions, particularly praising his distribution of text and pictures. His experimental results formed a comprehensive and important story. Panel members honored Julienne E. NeSmith with the Braun Award for her poster "Interactive effects of soil moisture and plant invasion on pine tree survival." NeSmith is a graduate student working with Associate Professor of Agronomy S. Luke Flory in the School of Natural Resources and Environment at the University of Florida in Gainesville. NeSmith investigated the separate and combined effects of drought and exotic grass invasion on the survival of native loblolly (Pinus tied) and slash (Pinus elliottii) pine in central Florida by manipulating environmental conditions in experimental garden plots. Cogongrass (Imperata cylindrica) is an aggressively invasive, highly flammable perennial grass which arrived in the southeastern United States in the early twentieth century. Drought and cogongrass invasion each separately decreased survival of both pine species, but invasion only exacerbated the effects of drought on the survival of loblolly pine. The presence of cogongrass offset the effects of drought on slash pine survival in the experimental garden plots. NeSmith attributed the greater survival of slash pine under drought conditions to higher soil moisture and humidity in invaded plots than non-invaded plots. Judges recognized NeSmith's ability to explain the experimental details and the management implications of her results and enjoyed her enthusiasm for the project. Environmental scientists from 50 U.S. states, U. S. territories, and countries around the world will converge on Portland, Oregon this August for the 102nd Annual Meeting of the Ecological Society of America. Five thousand attendees are expected to gather for nearly four thousand scientific presentations on breaking research and new ecological concepts at the Oregon Convention Center on August 6th through 11th, 2017. ESA invites reporters and institutional public information officers to attend the Annual Meeting for free. To apply, please contact ESA Communications Officer Liza Lester directly at email@example.com. The Ecological Society of America, founded in 1915, is the world's largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 10,000 member Society publishes five journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society's Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at http://www. .
News Article | May 16, 2017
Vietnam's government will likely ease requirements, placed on seafood companies, for declarations of conformity with food safety regulations, reports Vietnam Net. Officials said this during a conference with the country's ministries of Health, Industry and Trade and the Natural Resources and Environment, the Viet Nam Association of Seafood Exporters and Producers (Vasep) and local seafood companies. At the conference, Vasep proposed the government remove the requirement on declaration of conformity with technical and food safety regulations, arguing it takes seafood firms 15 days to complete the required procedure, which is too long and costly. Deputy minister of health Truong Quoc Cuong said Vasep’s request is reasonable as the food safety law only requires seafood firms to declare whether their products meet the technical standards or not. Cuong said that the ministry would try to amend the regulation within two or three months to meet the demand of Vasep and seafood firms, as well as the food safety law. Click here for the full story.
News Article | August 25, 2016
« Swiss team develops effective and low-cost solar water-splitting device; 14.2% solar-to-hydrogen efficiency | Main | Volkswagen, VW-branded franchise dealers in US reach agreement in principle to resolve diesel litigation » A new study from University of Michigan researchers challenges the assumption that crop-based biofuels such as corn ethanol and biodiesel are inherently carbon-neutral—i.e., that only production-related greenhouse gas (GHG) emissions need to be tallied when comparing them to fossil fuels. In an open-access paper published in the journal Climatic Change, the researchers conclude that once estimates from the literature for process emissions and displacement effects including land-use change are considered, US biofuel use to date is associated with a net increase rather than a net decrease in CO emissions. The study, based on US Department of Agriculture crop-production data, shows that during the period when US biofuel production rapidly ramped up, the increased carbon dioxide uptake by the crops was only enough to offset 37% of the CO emissions due to biofuel combustion over the period 2005-2013. The environmental justification rests on the assumption that, as renewable alternatives to fossil fuels, biofuels are inherently carbon neutral because the CO released when they are burned is derived from CO uptake during feedstock growth. That convention is premised on globally complete carbon accounting in which biogenic emissions are not counted in energy sectors when carbon stock changes are counted in land-use sectors. This assumption has been used in cap-and-trade programs and carbon taxes as promulgated to date, which address only fossil-derived CO emissions. However, errors arise when bioenergy is treated as carbon neutral in national and subnational policies, which do not impose globally coherent accounting that tracks all carbon stock changes. The carbon neutrality assumption is also embedded in lifecycle analysis (LCA), which traditionally focused only on production-related GHG emissions within a fuel’s supply chain. … Thus, although it was proposed as an objective way to compare fuels, LCA has become a form of scenario analysis. However, it is inferior in this regard to integrated assessment modeling (IAM), which uses a biogeochemically and economically coherent analytic framework that LCA lacks. Moreover, as a static framework, it fails to reflect the stock-and-flow dynamics that are fundamental to bioenergy systems. Indeed, policy applications of LCA raise serious questions regarding the limitations of the method. Given such concerns, it is useful to analyze the situation by a method other than LCA. The researchers applied Annual Basis Carbon accounting to investigate the changes in carbon flows directly associated with a vehicle-fuel system. Unlike LCA or other forms of carbon accounting used for climate policy to date, ABC does not treat biofuels as inherently carbon neutral; it tallies CO emissions on the basis of chemistry in the specific locations where they occur. ABC accounting reflects the stock-and-flow nature of the carbon cycle,— i.e., that changes in the atmospheric stock depend on both inflows and outflows. LCA, on the other hand, focuses only on inflows (GHGs discharged into the atmosphere). The system in the study was defined to include motor fuel consumption, fuel processing operations and resource inputs, including cropland for biofuel feedstocks. Thus, instead of modeling the emissions, lead author Professor John DeCicco and his colleagues analyzed real-world data on crop production, biofuel production, fossil fuel production and vehicle emissions—without presuming that that biofuels are carbon neutral. This is the first study to carefully examine the carbon on farmland when biofuels are grown, instead of just making assumptions about it. When you look at what’s actually happening on the land, you find that not enough carbon is being removed from the atmosphere to balance what's coming out of the tailpipe. When it comes to the emissions that cause global warming, it turns out that biofuels are worse than gasoline. So the underpinnings of policies used to promote biofuels for reasons of climate have now been proven to be scientifically incorrect. Policymakers should reconsider their support for biofuels. This issue has been debated for many years. What’s new here is that hard data, straight from America’s croplands, now confirm the worst fears about the harm that biofuels do to the planet. DeCicco’s co-authors include current and former students at the U-M School of Natural Resources and Environment and the U-M Program in the Environment, as well as a postdoctoral researcher at the Energy Institute. They are Danielle Yuqiao Liu, Joonghyeok Heo, Rashmi Krishnan, Angelika Kurthen and Louise Wang. Some funding for the study was provided by the American Petroleum Institute.
News Article | November 13, 2015
A new study by University of Michigan researchers suggests that the coffee plants themselves may hold biological weapons that could someday be harnessed in the fight against the coffee rust fungal pathogen. Those potential weapons are themselves fungi, a surprisingly diverse community of more than 300 species of them—including 15 likely fungal parasites—living on coffee leaves, within or alongside the yellow blotches that mark coffee rust lesions. Using an old-fashioned handheld paper punch, U-M researchers collected leaf samples from both infected and uninfected coffee leaves at coffee farms in Chiapas, Mexico, and in Puerto Rico. They found up to 69 fungal species living on a single quarter-inch-diameter leaf disc from uninfected leaves and up to 62 species on rust-infected leaf discs, according to Timothy James, a U-M mycologist and lead author of a paper scheduled for online publication Nov. 13 in Applied and Environmental Microbiology, a journal of the American Society for Microbiology. "Latin America is experiencing unprecedented epidemics of coffee rust, so identification of its natural enemies could aid in developing management strategies or in pinpointing species that could be used for biocontrol," said James, an associate professor in the Department of Ecology and Evolutionary Biology. "We recovered a surprisingly high fungal diversity in extraordinarily small samples of coffee leaf material—more than 300 species in a sampling area that, in total, was much smaller than the average size of a single coffee leaf. These hyper-diverse communities highlight the complexity of fungal diversity of unknown ecological function within these leaves." James' co-authors on the paper include U-M faculty members Ivette Perfecto of the School of Natural Resources and Environment and John Vandermeer of EEB, who have operated research plots at an organic coffee farm in southern Chiapas, Mexico, for nearly 20 years. The leaf-dwelling fungal species include 15 likely fungal parasites—organisms that grow on other fungi. The best-known of these so-called mycoparasites is white halo fungus, which is known to attack insects and help keep coffee rust fungus in check. It's possible that other fungal parasites on the leaves could be developed as biocontrol agents to combat coffee rust. But Vandermeer and Perfecto warn that tinkering with the complex ecological webs present on traditional shade-grown coffee farms could cause more harm than good. For example, spraying a newly developed fungicide on infected coffee plants could inadvertently destroy natural fungal enemies of coffee rust, worsening the problem. "Our approach is mostly one of prevention, keeping the farm strong and healthy with a lot of natural enemies that can combat the pests, rather than trying to solve a problem after it has emerged, which has been the approach of agronomists and pest-control management people," Perfecto said. In the study, leaf samples were collected from three coffee farms in Chiapas and five farms in Puerto Rico's central mountain region. DNA was extracted from 46 leaf discs, amplified using polymerase chain reaction, then sequenced using single-molecule DNA sequencing. A total of 313 fungal species (or closely related groups of species) were found. The 15 likely fungal parasites were identified based on their association with coffee rust lesions or their genetic similarity to other suspected mycoparasite species. Culturing and inoculation studies should now be used to test the candidate mycoparasitic fungi and verify that they are, in fact, parasites of coffee rust, the authors wrote. More information: Identification of putative coffee rust mycoparasites using single molecule DNA sequencing of infected pustules, Applied and Environmental Microbiology, 2015.
News Article | January 2, 2016
The largely unregulated industry has grown rapidly in the last two years to meet Chinese demand. Bauxite mining was blamed for turning the waters red on a stretch of coastline and surrounding rivers in eastern peninsula Malaysia after two days of heavy rain earlier this week. The cabinet wants to temporarily halt bauxite mining until regulations, licensing and environmental protection can be put in place, the source told Reuters on Saturday. "The idea is to suspend it for a time until all this is sorted out, but ultimately the prerogative for licensing lies with the state," the source told Reuters on condition of anonymity as he was not authorized to speak to media. Prime Minister Najib Razak has asked the resource minister to resolve the issues with the government of Malaysia's third-largest state and key bauxite producer Pahang, the source said. Waters and seas near Pahang's state capital Kuantan ran red earlier this week as downpours brought an increase in run-off from the ochre-red earth at the mines and the stockpiles, stoking environmental concerns. The state official in charge of the environment Mohd Soffi Abd Razak, however, said the pollution was caused by illegal mine operators and not by mines run by companies approved by the state government, according to local media reports. "We believe the illegal miners are causing the waters to be murky," local daily Malay Mail quoted the official as saying. Bauxite mines have sprung up in Malaysia since late 2014, notably in Kuantan, which faces the South China Sea. The mines have been shipping increasing amounts of the raw material to China, filling in a gap after Indonesia banned bauxite exports in early 2014, forcing the world's top aluminum producer, China, to seek supplies elsewhere. In the first 11 months of 2015, Malaysia exported more than 20 million tonnes of bauxite to China, up nearly 700 percent on the previous year. In 2013, it shipped just 162,000 tonnes. But the frantic pace of mining in Kuantan has brought in its wake a growing clamor of voices complaining of contamination of water sources and the destruction of the environment. Natural Resources and Environment Minister Wan Junaidi Tuanku Jaafar had previously said that Malaysia has come up with a raft of new regulations and guidelines for the industry, but needs the consent of the state government to impose them. The minister could not be immediately reached for a comment by Reuters on Saturday.
News Article | April 14, 2016
The huge pile of African elephant tusks, estimated to be worth $20 million, was first fed into in an industrial crusher to be pulverised, and then incinerated in a giant furnace in Port Dickson in southern Malaysia. Malaysia has previously announced in Parliament that 4,624 ivory tusks were confiscated between 2011 and 2014. "This is our first-ever ivory destruction. We want to send a strong message to the world that Malaysia does not compromise in protecting endangered species," Natural Resources and Environment Minister Wan Junaidi Tuanku Jaafar told AFP. The international ivory trade, with rare exceptions, has been outlawed since 1989 after the population of African elephants declined from millions in the mid-20th century to just 600,000 by the end of the 1980s. But poachers and smugglers have continued to exploit demand, mainly from Asia and particularly China, where ivory is highly prized for medicinal and decorative uses. Malaysia, a signatory to the Convention on International Trade in Endangered Species (CITES), has seized a number of shipments over the years, mostly by sea. In March, officials said they had confiscated 159 kilogrammes (350 pounds) of ivory smuggled by passengers aboard commercial flights. Wan Junaidi said the tusks destroyed Thursday originated from 11 African countries ranging from Ghana to Tanzania. They were publicly destroyed to deter smugglers, he said, while adding it also was partly in response to questions raised by conservationists over the fate of seized ivory. "I do not want any of the seized ivory lost. If the ivory is no longer needed to be kept for evidence, we will destroy it," he said. The event was witnessed by foreign diplomats and conservation groups. "We look forward to these good intentions being bolstered with concrete actions to tackle the factors that have made Malaysia a key transit point in the global ivory trade," said Kanitha Krishnasamy, programme manager for TRAFFIC in Southeast Asia.
News Article | January 4, 2016
However, most of the expected declines in Lake Erie will not be as extreme as some experts have predicted, according to the food-web study by the University of Michigan's Hongyan Zhang and colleagues from other American and Canadian research institutions. A few fish species, including smallmouth bass, would likely increase. The study is the first to use a food-web model to examine the likely impacts of bighead and silver carp in Lake Erie. These plankton-eating Asian carp are established in watersheds close to the Great Lakes but not in the lakes themselves. The invasive carp would likely affect Lake Erie's food web in two main ways: They would likely compete with native fish by eating their food, and juvenile Asian carp would likely become food for fish-eating fish. According to the study, walleye, rainbow trout, gizzard shad and emerald shiners could all decline, with declines in emerald shiner of up to 37 percent. Smallmouth bass stood to gain the most, with increases of up to 16 percent. A paper summarizing the findings was published online Dec. 30, 2015 in the journal Transactions of the American Fisheries Society. The model results suggest that Asian carp could eventually account for up to 34 percent of the total fish weight in the lake, said Zhang, assistant research scientist at U-M's Cooperative Institute for Limnology and Ecosystems Research in the School of Natural Resources and Environment. "Fortunately, the percentage would not be as high as it is today in the Illinois River, where Asian carp have caused large changes in the ecosystem and have affected human use of the river," she said. Previous predictions of Asian carp impacts in the Great Lakes have ranged widely. Some experts say Asian carp could decimate Great Lakes fisheries and food webs, while others suggest the effects would likely be minor because much of the Great Lakes is not a suitable habitat for Asian carp. >Results of the new study fall somewhere between the two extremes. "This study goes beyond previous efforts in two significant ways. It focuses on the food webs and—where model input data were not available—it includes uncertainty estimates from experts," said co-author Ed Rutherford, a fisheries biologist at the Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor, a U.S. National Oceanic and Atmospheric Administration facility. To include uncertainty in model predictions, team members interviewed 11 leading experts on Asian carp biology and Great Lakes ecology and fisheries, then incorporated the experts' estimates into the model. The experts were also asked to indicate the level of uncertainty associated with each statement they provided. "We don't know how these two Asian carp species are going to do in Lake Erie, so we have to incorporate that uncertainty into our model projections," said co-author Doran Mason, a research ecologist at GLERL. "It's like using computer models to predict a hurricane's path and intensity and including the margin of error in the forecast." The team has shared its Lake Erie results with Great Lakes resource managers to help inform decisions related to Asian carp. Of the Great Lakes, Erie may be most vulnerable to Asian carp invasion due to its proximity to waters where Asian carp exist, the presence of adequate food, and the availability of suitable spawning habitat. The same research team is now working on modeling studies to predict Asian carp impacts in lakes Michigan, Huron and Ontario, as well as a study of the regional economic impacts associated with Asian carp in Lake Erie.
News Article | March 14, 2016
The study's results suggest that Lake Huron resource managers should focus their efforts on restoration of native fish species such as lake trout, walleye, lake whitefish and lake herring. The findings also suggest that if current trends continue, Lake Michigan will likely experience an alewife collapse similar to Lake Huron's, followed by the crash of its Chinook salmon fishery there. "These results serve as a reality check for those who continue to pressure the resource managers to stock Chinook salmon in Lake Huron," said study co-author Sara Adlerstein-Gonzalez, a fishery scientist at U-M's School of Natural Resources and Environment. "The findings are also good news for native fish species and for the restoration of the entire Lake Huron ecosystem. Maybe we should celebrate the improvements in the native fish populations and try to adapt to this new situation." A paper summarizing the findings is scheduled for online publication in the journal Ecosystems on March 14. The paper's first author is Yu-Chun Kao, who conducted the work for his doctoral dissertation at U-M under Adlerstein-Gonzalez. He is now a postdoctoral researcher at Michigan State University and works at the U.S. Geological Survey's Great Lakes Science Center in Ann Arbor. The other author of the Ecosystems paper is Edward Rutherford of the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory in Ann Arbor. Pacific salmon were introduced into the Great Lakes 50 years ago to establish a new recreational fishery and to help control alewives, a non-native species that entered the lakes in the late 1940s and early 1950s. Alewives soon became the main prey species for Chinook salmon and lake trout, which are staples of a Great Lakes fishery valued at more than $4 billion per year. Lake Huron's alewife population collapsed in 2003, and a sharp Chinook salmon decline soon followed. The state of Michigan and the province of Ontario stopped stocking Chinook salmon in southern Lake Huron in 2014 but continue to stock in the northern part of the lake. In Lake Michigan, where populations of both alewives and salmon are declining, stocking of Chinooks continues at significantly reduced levels. The new study is the first attempt to use a food-web modeling approach to assess the various factors behind the 2003 collapse of Lake Huron alewives and the implications for future fish populations there. The total weight or "biomass" of alewives in Lake Huron plunged by more than 90 percent between 2002 and 2003, and the exact causes of the collapse are still debated by anglers and biologists. Some researchers have suggested the alewife collapse was mainly due to too much predation by Chinook salmon and native lake trout. Others say it likely resulted from a drop in food availability tied to the explosive spread of zebra and quagga mussels starting in the late 1980s. The computer simulations in the new study show that the collapse was caused by a combination of predation and food limitation—and that predation alone would not have caused the crash. The spread of the non-native mussels, coupled with declining levels of the nutrient phosphorus entering the lake from rivers and streams, were essential factors, according to the new study. The Lake Huron dominoes fell sequentially, according to the report. First came increased predation of alewives, due initially to heavier stocking of Chinook salmon and later the result of increased natural reproduction of salmon and a drop in sea-lamprey mortality. Predation of Lake Huron alewives by Chinook salmon likely peaked in the mid-1980s and then remained roughly constant until the alewife collapse, according to the new simulations. Beginning in the 1990s, quagga mussels spread quickly at a time when the level of phosphorus flowing into the lake from rivers and streams was dropping in response to nutrient abatement programs initiated in the 1970s. Mussels in Lake Huron's Saginaw Bay compounded the problem by sucking up and storing nutrients near the shore, preventing them from making it into Lake Huron's main basin. The loss of essential nutrients in the main basin reduced the amount of algae at the base of the Lake Huron food web. Zooplankton, tiny animals that feed on algae and that provide food for small fish such as alewives and rainbow smelt, suffered. At the time, alewives and rainbow smelt were the two most important prey species for Chinook salmon in Lake Huron. The new computer simulations show that rainbow smelt suffered significant declines before alewives did, dropping 78 percent by 2002. Deprived of a favorite food, Chinook salmon began to rely more heavily on alewives, and this increased predation hastened the alewife population collapse, according to the study. This sequence of events can be used to assess the likelihood of an alewife and Chinook salmon collapse in lakes Michigan and Ontario, the researchers said. "We are seeing all the same warning signs in lakes Michigan and Ontario," Kao said. "We're seeing decreasing nutrient loads, a decrease in soft-bodied, bottom-dwelling invertebrates due to the mussels, a decrease in rainbow smelt and, as a result, Chinook salmon feeding almost solely on alewives." Explore further: An Illuminating Great Lakes Tale: The Alewife and the Opossum Shrimp