WEST LAFAYETTE, Ind. – Indiana’s average air temperatures are expected to rise by as much as 6 degrees Fahrenheit by mid-century, warming and reducing wintertime ice cover on the state’s lakes, streams, and rivers. At the same time, increases in winter and spring rainfall will likely wash more nutrients from farm fields into those water bodies, adding significant challenges to already fragile ecosystems.
Those are some of the key points in “Aquatic Ecosystems in a Shifting Indiana Climate,” the latest report from the Purdue University-based Indiana Climate Change Impacts Assessment, released during a community briefing Sept. 12 at Bass Pro Shops in Portage, Indiana.
“Changes in Indiana’s climate are going to affect the timing of water flows, the quality of water and water temperatures. All of these things have major implications for the wide variety of animals and plants that live in aquatic ecosystems,” said Jeff Dukes, director of the Purdue Climate Change Research Center. “Climate change is an additional stressor to Indiana’s native fish population. We already have invasive fish in many of our water bodies, and we have added a wide variety of pollutants and nutrients to our streams. How well some of our native populations will be able to deal with this accumulation of stresses piling up on them is still unclear.”
Rising water temperatures will likely shift stratification – the layering of water at different depths in lakes. That may improve or increase habitat for the state’s warm water fish.
However, those rising temperatures and increasing spring rain totals will send more nutrients from farm fields into nearby waters. That combination is problematic for many coldwater species, such as cisco, a native fish that used to exist in about 50 of the state’s lakes but has already suffered from rising temperatures.
“Because many of our lakes are very nutrient-rich, they experience large algal blooms in late spring and summer, which may grow larger with warmer temperatures and more spring runoff. Dead algae later settle to the lake’s bottom and are decomposed by bacteria, depleting the water’s oxygen,” said Tomas Höök, Purdue professor of fisheries and aquatic sciences, director of Illinois-Indiana Sea Grant and lead author of the report. “This creates hypoxia in bottom waters. Cisco are going to get really squeezed from warmer temperatures on the surface and lack of oxygen on the bottom. Cisco persist in six lakes right now, but they may not be present in the state much longer.”
Changing precipitation patterns could also negatively impact Indiana’s already-endangered freshwater mussels, with different effects across seasons. Drier summers will likely reduce water levels in streams where the mussels live, exposing them to intolerable conditions. In the spring increased stream flows could dislodge mussels from their habitats in rivers.
Wetlands may stay wet longer in the spring and dry more than usual during the summer, altering ecosystems that depend on critical seasonal timing. Some plants and animals adapted to Indiana’s current climate may not thrive here in the coming decades.
In Lake Michigan, where near-surface temperatures have already warmed by 3 degrees Fahrenheit since 1980, temperature changes could lead some coldwater fishes, such as salmon, trout and lake whitefish, to move further offshore to deeper waters. As a result, they may spend less time in the Indiana waters of Lake Michigan, which are relatively shallow and warm. The lake’s warmer temperatures could also affect growth, spawning or reproductive processes for many valuable commercial and sport fish species.
Höök suggests those tasked with managing Indiana’s aquatic ecosystems focus on maintaining or increasing both genetic and habitat diversity.
“Trying to make precise predictions of how species will respond to climate change is tricky,” Höök said. “Climate change is one of many factors impacting aquatic organisms, along with pollution, invasive species, fisheries harvest and habitat destruction. But maintaining a diversity of species, habitats and genetic variation within these ecosystems should help buffer against these different stressors.”
Carolyn Foley, research coordinator for Illinois-Indiana Sea Grant and a co-author on the report, suggests that people all over the state have the ability to help work on the issue, from researchers to everyday people.
“There are a lot of freshwater ecosystems in Indiana—streams, rivers, wetlands, lakes, reservoirs,” said Foley. “And a lot of great, water-related research happening here, too. In this report, researchers worked together to paint a rich picture of how aquatic ecosystem components might be affected by climate change. If the general public wants to help, they could think about volunteering with local watershed alliances or other organizations trying to improve waterways through cleanups, habitat restoration, or decreasing runoff from land to water. Keeping waters as healthy as possible will support robust ecosystems, which are more likely to successfully navigate the changes that are coming.”
The Indiana Climate Change Impacts Assessment (IN CCIA) is compiling the latest scientific research into a series of easily understandable reports about climate change impacts in 10 topic areas: climate, health, forest ecosystems, aquatic ecosystems, urban green infrastructure, tourism and recreation, agriculture, water resources, energy, and infrastructure. The assessment team consists of more than 100 experts from Purdue and other Indiana institutions.
The IN CCIA has now released six reports. All are available on the IN CCIA website at http://indianaclimate.org/. For more information about the IN CCIA, go to the website or follow on social media at @PurdueCCRC, #ClimateChange, #INCCIA.
Writer: Brian Wallheimer, 765-532-0233, bwallhei@purdue.edu
Sources: Jeff Dukes, 765-496-3662, jsdukes@purdue.edu
Tomas Höök, 765-496-6799, thook@purdue.edu
Carolyn Foley, cfoley@purdue.edu
Evolution is often viewed through the lens of thousands of years. But it may have taken humans only a century or so to force evolutionary changes to fish in the Great Lakes, according to a Purdue University report.
Environmental factors over long periods of time often lead to beneficial traits in animals. But Tomas Höök, a professor in the Department of Forestry & Natural Resources at Purdue University and director of Illinois-Indiana Sea Grant, and colleagues believe there is evidence of fisheries-induced evolution (FIE) in the Great Lakes.
“Fishing and harvesting creates strong pressure that could select for certain genetic material in a fish population and lead to rapid human-induced evolution of the population,” Höök said.
A review, published in the Journal of Great Lakes Research, presents the case for rapid evolution, including case studies of two important fishery species — yellow perch and lake whitefish.
For yellow perch, Lake Michigan commercial fishing operations in the early 1990s overharvested perch, in particular large female fish. This led to an abundance of male fish as well as smaller females, since they were the most likely to have an opportunity to reproduce.
After a collapse of yellow perch populations, commercial fishing for the species was shut down and recreational angling for the species was restricted. Research shows that yellow perch quickly started to sexually mature later and at larger sizes once they weren’t susceptible to harvest.
“Importantly, this research suggests that FIE can occur rapidly, but that changes are reversible,” wrote the authors, which included Erin Dunlop from the Ontario Ministry of Natural Resources and Forestry, as well as Zachary Feiner and Höök from Purdue.
Lake whitefish populations have been affected by overfishing and invasive species in Lake Michigan and Lake Huron. Models suggest that high harvest rates and harvesting before whitefish reach sexual maturation could lead to rapid declines in population and the size at which fish mature.
Höök said fisheries-induced evolution has been widely studied in marine systems, but more needs to be done on freshwater species since many can be important ecologically and commercially.
“We need to assess the potential for fisheries-induced evolution in these systems to better understand the extent to which fishery managers can and should think about FIE when making key management decisions affecting fish populations,” Höök said.
WEST LAFAYETTE, Ind. – Purdue University scientists led a comprehensive analysis of research concerning the effects of microplastics on aquatic life, with the results showing widely different impacts among different types of animals. Strong negative effects were particularly apparent for small animals, such as larval fish and zooplankton, a source of food for many species, suggesting serious potential consequences that could ripple throughout the food web.
Tomas Höök, an associate professor in Purdue University’s Department of Forestry and Natural Resources and director of the Illinois-Indiana Sea Grant College Program, led a team that designed a meta-analysis of research related to the effects of microplastics on aquatic life. The analysis, published in the journal Science of the Total Environment, used results from 43 other studies that each considered the effects of microplastics on consumption of food, growth, reproduction, and/or survival of aquatic animals. The analysis mathematically calculated one or more effect size(s) for each study, then those effects were combined statistically to understand the big-picture effect on animals. The animals included in this study were all aquatic but ranged from fish to mussels to sea urchins to worms.
The most significant findings included:
* Considering all effect sizes together, on average, exposure to microplastics negatively affects consumption, growth and survival of aquatic animals.
* However, the results are highly varied and not all groups of animals were affected in the same ways.
* Microplastics significantly reduced growth, reproduction and survival of zooplankton.
* When exposed to microplastics, larval and juvenile fish see negative effects on natural consumption of other foods.
“One of the types of organisms that seems to be affected is crustacean zooplankton, which are the main prey for many small fishes,” said Höök, whose findings were published in the journal Science of the Total Environment. “The fact that these very small organisms are consuming these microplastics, altering their growth, reproduction and survival, means there could be consequences up the food web. If zooplankton numbers decline, there may be less food available for organisms at higher trophic levels.”
Microplastics, small pieces of the material less than 5 millimeters in size, have been found in waters and soils in and around all seven continents. They come from a wide variety of sources, including broken-down food and drink containers, fibers from synthetic clothing, industrial waste and some beauty products.
Many organizations and governments have tried to reduce the amount of plastic pollution reaching water and wildlife, but the effects these microplastics are having on the range of aquatic life hasn’t been clear. Purdue’s meta-analysis puts all the current, applicable research into perspective.
“Our results most strongly support the notion that exposure to microplastics leads to negative effects on consumption of aquatic organisms, with less compelling and consistent evidence that growth, reproduction or survival of aquatic organisms is negatively affected by exposure to microplastics,” the authors find.
Carolyn Foley, a research associate in Purdue’s Department of Natural Resources and research coordinator for Illinois-Indiana Sea Grant, said few of the studies analyzed included microplastic fibers, the small pieces of plastic that break away from larger pieces. That might be an area to focus future research. She also suggested that while the effects on upper-level functions, such as reproduction and survival, were highly variable, there isn’t a similar summary of research examining how microplastics might be altering aquatic life in less perceptible ways.
“If microplastics aren’t having immediate effects on these upper-level functions, maybe there are less-obvious and cumulative negative impacts,” said Foley, who is the lead author of the paper. “It may be more important to look at finer-level effects, including molecular-level effects.”
The Illinois-Indiana Sea Grant College Program and Purdue’s Department of Forestry and Natural Resources funded the research.
Tomas Höök has taken the lead as director of Illinois-Indiana Sea Grant, managing program administration at Purdue University after the transition from University of Illinois. Höök, who has been with IISG since 2010, was previously the program’s associate director of research. He replaces Brian Miller, who served as IISG director for the past ten years.
“As director, I initially hope to help guide the program through the transition period as our administration moves from Illinois to Purdue and new staff members come on board, all while dealing with uncertain federal funding scenarios,” Höök said. “Eventually, I’d like to help our program develop new initiatives, partnerships and approaches to help inform and empower Illinois and Indiana communities.”
Höök holds an appointment as associate professor of fisheries and aquatic sciences in the Department of Forestry and Natural Resources at Purdue University. He directs a Purdue research lab that investigates environmental questions at the interface between applied and basic ecology, focusing on fish and fisheries ecology in the Great Lakes.
“Purdue is thrilled that Dr. Tomas Hook will serve as the next director of Illinois-Indiana Sea Grant,” said Robert Wagner, head of Purdue’s Department of Forestry and Natural Resources. “Tomas brings outstanding previous experience with IISG, as well as incredible expertise, to this leadership position. We are happy to once again serve as the lead institution for the next phase of Illinois-Indiana Sea Grant.”
Höök grew up in Sweden but completed high school in Alabama when his family moved to the United States and he now holds dual citizenship in both countries. He received his BS, MS and PhD from the University of Michigan. Prior to joining IISG and Purdue University, he worked at the Cooperative Institute for Limnology and Ecosystems Research (now known as CIGLR) and as a visiting scientist at Stockholm University in Sweden. Höök is also a former president of the International Association for Great Lakes Research.
“I enjoy working with IISG because I believe our program makes a real difference through applied research and engagement, thereby facilitating communities in Illinois and Indiana to improve quality of life and environmental conditions around Lake Michigan,” said Höök. “I also appreciate that IISG staff members are a dedicated, knowledgeable and fun bunch to work with.”
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