News Article | November 21, 2016
Up until now, atmospheric models and hydrodynamic models have remained separate to a large extent in the Great Lakes region, with only a few attempts to loosely couple them. In a new study, published online this week in the Journal of Climate, an integrated model brings together climate and water models. The collaborative work is the product of researchers from Michigan Technological University, Loyola Marymount University, LimnoTech and the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory. Pengfei Xue, an assistant professor of civil and environmental engineering at Michigan Tech, led the study through his work at the Great Lakes Research Center on campus. "One of the important concepts in climate change, in addition to knowing the warming trend, is understanding that extreme events become more severe," Xue says. "That is both a challenge and an important focus in regional climate modeling." To make those connections, the model specifically uses two-way coupling and 3-dimensional modeling to connect atmospheric and lake body interactions. Two-way coupling is like a two-way street and enables feedback between variables; other models use preset inputs that act more like one-way streets. Current models also rely on 1-D lake models that cannot account for the dynamic nature of hydrologic processes in bodies of water as large as the Great Lakes. For comparison, most widely used global climate models use only tens of grid points (roughly 0.5 degree resolution) to cover all of the Great Lakes, if they account for the lakes at all. To create a more nuanced view, like what has been accomplished already in ocean coastline modeling, the new model simulates the hydrodynamics of the Great Lakes region with 3-D hydrodynamic model constructed of 40 vertical layers and 2-kilometer horizontal grid resolution. That's roughly 50,000 grids for each layer, which enables feedback between air and water data. The datasets used are so large that they can only run on a supercomputer. Xue uses the Superior supercomputer at the Great Lakes Research Center. Xue and his team vetted the model's accuracy by comparing its simulations to historical records and satellite data. "This kind of approach has been recognized as a critical step in the Great Lakes region that has been building over the past decade," Xue says. The next stage of the research will expand the model to include surface water runoff. Refining the model is a community effort, and the team plans to work with current collaborators to apply and test the limits of the model. In its current version, the new model provides better footing to further Great Lakes research. By doing so, scientists will glean more information about everything from regional climate change and shipping to oil spill mitigation and invasive species.
News Article | April 2, 2016
If the old pipelines under the Straits of Makinac burst, more than 700 miles of the Great Lakes shoreline are at at risk for oil spills, a University of Michigan study has revealed. The computer-modeling study conducted by hydrodynamics expert David Schwab included 840 oil spill simulations from the Enbridge Line 5 pipeline that lies underneath the Mackinac strait. The simulation, under the support of National Wildlife Federation, found more than 245 kilometers (152 miles) of Huron and Michigan lakes shoreline could be greatly affected by a single oil spill. Once all 840 simulated spills were plotted, the researchers found that about 1,162 kilometers (720 miles) of U.S. and Canadian shorelines would become vulnerable to the spills. Those with the highest risk include Bois Blanc and Mackinac islands, as well as areas that are directly west and east of Mackinaw City. Beaver Island, Harbor Springs, Cross Village, Cheboygan and other communities along the Huron and Michigan lakes' shoreline would also be greatly affected. The report is, by far, the only study that detailed the length and speed in case an oil spill occurs. Schwab's study provides a very good material the government can use when planning for a spill-response. Mike Shriberg, National Widlife Federation's Great Lakes Regional Center regional executive director, believes that the study is an important component of assessing Line 5's risk to the Great Lakes. "Michigan public officials have an important decision to make about how to protect our communities, economy, wildlife and Great Lakes from an oil spill disaster," Shriberg said. Using a high-resolution hydrodynamic model developed by Schwab ad Eric Anderson of the National Oceanic and Atmospheric Administration's (NOAA) Great Lakes Environmental Research Laboratory, the researchers were able to do simulations that incorporated approximations in case an oil spill occurs at the halfway point of the 5-mile wide Straits of Mackinac. The study also showed several significant findings including that in one of the 840 simulations, the open waters of Lake Huron and Lake Michigan would have 60 percent and 15 percent of visible oil, respectively. The open water, at risk, is 44,405 square kilometres (17,318 square miles), almost equal to the combined surface areas of lakes Ontario and Erie. A single hypothetical spill covers a maximum open water area of 1,600 square kilometres (624 square miles), which is bigger than Lake St. Clair. The simulation also noted that visible surface oil can arrive at the shore in just 2.5 hours. The whole Mackinac Island could be severely affected in just nine hours and can reach Cheboygan in 30 hours. The extent of the oil spill is due to the volume of oil that passes through Enbridge Line 5 pipeline under the Straits of Mackenzie. About 20 million gallons of light synthetic crude oil, light crude oil, and natural gas liquids pass through the pipes each day. In case of a 25,000 barrel spill scenario, Schwab said a cleanup of Mackinac Island is 90 percent probable. It is important to note that the study simulation did not include a containment action to stop the oil spill at the Straits of Mackinac. The present study complements Schwab's 2014 study, which only used two computer simulations, and aims to help Michigan officials to decide on the old pipeline before an oil spill happens and a beach cleanup becomes necessary. A previous study by marine scientists from University of Georgia who lab-simulated an oil spill, which released 172 million gallons of oil in the Gulf of Mexico, revealed that chemical dispersants used to remove oil from the water were not able to fully degrade it and even hurt the oil-degrading microbes present in the water.
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
McCarty L.S.,Scientific Research and Consulting Newmarket |
Landrum P.F.,Great Lakes Environmental Research Laboratory |
Luoma S.N.,U.S. Geological Survey |
Meador J.P.,National Oceanic and Atmospheric Administration |
And 3 more authors.
Integrated Environmental Assessment and Management | Year: 2011
The tissue residue dose concept has been used, although in a limited manner, in environmental toxicology for more than 100 y. This review outlines the history of this approach and the technical background for organic chemicals and metals. Although the toxicity of both can be explained in tissue residue terms, the relationship between external exposure concentration, body and/or tissues dose surrogates, and the effective internal dose at the sites of toxic action tends to be more complex for metals. Various issues and current limitations related to research and regulatory applications are also examined. It is clear that the tissue residue approach (TRA) should be an integral component in future efforts to enhance the generation, understanding, and utility of toxicity testing data, both in the laboratory and in the field. To accomplish these goals, several key areas need to be addressed: 1) development of a risk-based interpretive framework linking toxicology and ecology at multiple levels of biological organization and incorporating organism-based dose metrics; 2) a broadly applicable, generally accepted classification scheme for modes/mechanisms of toxic action with explicit consideration of residue information to improve both single chemical and mixture toxicity data interpretation and regulatory risk assessment; 3) toxicity testing protocols updated to ensure collection of adequate residue information, along with toxicokinetics and toxicodynamics information, based on explicitly defined toxicological models accompanied by toxicological model validation; 4) continued development of residueeffect databases is needed ensure their ongoing utility; and 5) regulatory guidance incorporating residue-based testing and interpretation approaches, essential in various jurisdictions. ©:2010 SETAC.
Vanderploeg H.A.,National Oceanic and Atmospheric Administration |
Liebig J.R.,National Oceanic and Atmospheric Administration |
Nalepa T.F.,National Oceanic and Atmospheric Administration |
Fahnenstiel G.L.,Great Lakes Environmental Research Laboratory |
Pothoven S.A.,Great Lakes Environmental Research Laboratory
Journal of Great Lakes Research | Year: 2010
We determined the clearance rates of the profunda morph of the quagga mussel (Dreissena bugensis) using seston and Cryptomonas ozolini, a high-quality algal food, for the temperature range 1-7°C, which is the full temperature range this morph is likely to experience during isothermal conditions or in the hypolimnion of deep lakes. Experiments at 3°C with the shallow-water morph of the quagga and the zebra mussel provided very similar results. The clearance rates were combined with dreissenid abundance in 0-30. m, 30-50. m, 50-90. m, and > 90m depth zones of the southern basin of Lake Michigan to calculate a maximum (using Cryptomonas) and minimum (using seston) fraction of the water column cleared (FC) per day in the different depth zones at 3°C to determine dreissenid impact on the spring phytoplankton bloom from 1994 to 2008. Starting in 2003 or 2004 with the replacement of zebra mussels by quagga mussels in shallow water and expansion of quagga mussel biomass in deep water, FC began to exceed likely phytoplankton growth in the 30-50. m zone. In 2007-2008, FC greatly exceeded likely phytoplankton growth by a factor of about 5 in the 30- to 50-m depth zone, where dreissenids were extremely abundant. Low FC in the offshore region led to the hypothesis of a mid-depth carbon (C) and phosphorous (P) sink caused by mussel uptake of seston-associated C and P that affected not only the mid-depth region, but also the offshore region "downstream" of the mid-depth zone. © 2010.
Vanderploeg H.A.,National Oceanic and Atmospheric Administration |
Pothoven S.A.,Great Lakes Environmental Research Laboratory |
Fahnenstiel G.L.,Great Lakes Environmental Research Laboratory |
Cavaletto J.F.,National Oceanic and Atmospheric Administration |
And 5 more authors.
Journal of Great Lakes Research | Year: 2012
We examined seasonal dynamics of zooplankton at an offshore station in Lake Michigan from 1994 to 2003 and 2007 to 2008. This period saw variable weather, declines in planktivorous fish abundance, the introduction and expansion of dreissenid mussels, and a slow decline in total phosphorus concentrations. After the major expansion of mussels into deep water (2007-2008), chlorophyll in spring declined sharply, Secchi depth increased markedly in all seasons, and planktivorous fish biomass declined to record-low levels. Overlaying these dramatic ecosystem-level changes, the zooplankton community exhibited complex seasonal dynamics between 1994-2003 and 2007-2008. Phenology of the zooplankton maximum was affected by onset of thermal stratification, but there was no other discernable effect due to temperature. Interannual variability in zooplankton biomass during 1994 and 2003 was strongly driven by planktivorous fish abundance, particularly age-0 and age-1 alewives. In 2007-2008, there were large decreases in . Diacyclops thomasi and . Daphnia mendotae possibly caused by food limitation as well as increased predation and indirect negative effects from increases in . Bythotrephes longimanus abundance and in foraging efficiency associated with increased light penetration. The . Bythotrephes increase was likely driven in part by decreased predation from yearling and older alewife. While there was a major decrease in epilimnetic-metalimnetic herbivorous cladocerans in 2007-2008, there was an increase in large omnivorous and predacious calanoid copepods, especially those in the hypolimnion. Thus, changes to the zooplankton community are the result of cascading, synergistic interactions, including a shift from vertebrate to invertebrate planktivory and mussel ecosystem impacts on light climate and chlorophyll. © 2012.
News Article | January 5, 2016
Invasive Asian carp, steadily moving northward for decades, could eventually make up a third of the fish weight in Lake Erie if they successfully invade and become established there, researchers say. Voraciously consuming plants and animals that serve as food for native species as they work their way north through the Mississippi River system, the Asian carp could cause many Lake Erie native fish species to go into decline, including important commercial and sport species like walleye and rainbow trout, scientists say. That's one finding of a study by University of Michigan researchers, working with colleagues at other research institutions in America and Canada. They used a computer model to predict the likely impact on food webs if silver and bighead varieties of Asian carp gain a foothold in Lake Erie, they report in the journal Transactions of the American Fisheries Society. While some native species like walleye and trout would suffer as the carp out-compete them for food, some other fish-eating species, such as smallmouth bass, might benefit from an abundance of juvenile carp as a new food source, the researchers suggest. Still, Asian carp could eventually account for up to 34 percent of the lake's total fish weight, says UM researcher Hongyan Zhang. "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 says. Experts have differed in their predictions of what impacts Asian carp could have on the Great Lakes; some believe the carp may decimate fisheries and lake food webs, while other researchers suggest the Great Lakes are not suitable carp habitat and the effects of their presence would be minor. The new study falls somewhere in between in its suggestions, the researchers say. Asian carp have established themselves in watersheds adjacent to the Great Lakes but have not been found in the lakes themselves yet, which makes the study's predictions subject to modification, they say. "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," says study co-author Doran Mason, an ecologist at the Great Lakes Environmental Research Laboratory. "It's like using computer models to predict a hurricane's path and intensity and including the margin of error in the forecast." The researchers are also conducting modeling studies on possible carp impacts on other Great Lakes, including Michigan, Huron and Ontario.
Moore N.,Zhejiang University |
Moore N.,Michigan State University |
Alagarswamy G.,Michigan State University |
Pijanowski B.,Purdue University |
And 6 more authors.
Climatic Change | Year: 2012
Climate change impacts food production systems, particularly in locations with large, vulnerable populations. Elevated greenhouse gases (GHG), as well as land cover/land use change (LCLUC), can influence regional climate dynamics. Biophysical factors such as topography, soil type, and seasonal rainfall can strongly affect crop yields. We used a regional climate model derived from the Regional Atmospheric Modeling System (RAMS) to compare the effects of projected future GHG and future LCLUC on spatial variability of crop yields in East Africa. Crop yields were estimated with a process-based simulation model. The results suggest that: (1) GHG-influenced and LCLUC-influenced yield changes are highly heterogeneous across this region; (2) LCLUC effects are significant drivers of yield change; and (3) high spatial variability in yield is indicated for several key agricultural sub-regions of East Africa. Food production risk when considered at the household scale is largely dependent on the occurrence of extremes, so mean yield in some cases may be an incomplete predictor of risk. The broad range of projected crop yields reflects enormous variability in key parameters that underlie regional food security; hence, donor institutions' strategies and investments might benefit from considering the spatial distribution around mean impacts for a given region. Ultimately, global assessments of food security risk would benefit from including regional and local assessments of climate impacts on food production. This may be less of a consideration in other regions. This study supports the concept that LCLUC is a first-order factor in assessing food production risk. © 2011 The Author(s).
Hawley N.,Great Lakes Environmental Research Laboratory |
Redder T.,Limno Technology |
Beletsky R.,University of Michigan |
Verhamme E.,Limno Technology |
And 2 more authors.
Journal of Great Lakes Research | Year: 2014
An integrated hydrodynamic and sediment transport model was applied to Saginaw Bay for the ice-free portions of 2009 and 2010. Observations of surface waves and suspended sediment concentration made during the spring of both years were used to constrain the model and to validate the model output. The results show that sediment resuspension in both the inner and outer bay is due almost entirely to surface wave action, and that the bulk of the resuspension events occur during the fall of each year. Although the model accurately predicted the occurrence of resuspension events, it did not always accurately simulate the amount of material resuspended. Because resuspension mixes bottom sediment into the water column and makes it and associated nutrients available to the biota, the effects of sediment resuspension need to be accounted for in any water quality model of the bay. Better specification of both the surface waves and the initial specification of the bottom sediment would probably improve the performance of the model. © 2013.