Fish Ecology: A True ‘Canary in a Coal Mine’

Jamilynn Polettto in her lab
Natural Resources Systems: Exploring Fish, Wildlife, Landscapes, and Water

Fish Ecology: A True ‘Canary in a Coal Mine’

Improving Human Health Through the Study of Fish Physiology

Leanne Gamet
Interview with Jamilynn Poletto by Leanne Gamet

Fish are an indicator species and may even be a signpost for human health dangers. University of Nebraska–Lincoln assistant professor in the School of Natural Resources and fish physiologist Jamilynn Poletto explained that some fish species are seen as somewhat of a “canary in a coal mine,” as they are often early indicators for issues that could affect humans. Similar to the canaries that were sent down coal mines to detect the threat of dangerous gases that could be hazardous to coal miners, fish can help humans detect issues in water systems. 

“If fish are sick, it is a really good indication that there is something wrong in that ecosystem. For fish in particular, it is usually associated with water quality. And unfortunately, the water that fish are swimming in is oftentimes the same water that we are drinking,” Poletto said. “So anything that’s going to be potentially detrimental to the health and survival of a fish could be detrimental to us [humans] as well.” 

Due to their sensitivity to various environmental conditions, a sick fish species could be a warning sign that other animals in the ecosystem could potentially become subject to the condition as well. 

Ecology, or the behavior of organisms with others as well as their environment, has become a second language for Poletto. Specifically, Poletto and her research team determine how changes in the environment, many times referred to as stressors, interrupt normal fish behavior. Given the importance of fish to an ecosystem, Poletto also outlines ways to conserve various fish species. Together, this information can help to better understand ways that environmental impacts can alter the health and well-being of various fish species as well as the quality of water in a given area.

Environmental Stressors for Fish

Changes in the environment can cause stress to various fish species because the change interrupts typical fish behavior. Three main stressors impact fish species in Nebraska: rising temperatures, water level fluctuations and pesticides.  

First, rising temperatures cause a significant stress to fish because fish are ectotherms. An ectotherm’s body temperature reflects the temperature of the water.  Therefore, rising temperatures in the environment will, in turn, raise the body temperature of the fish. 

“Every aspect of physiology is dependent on temperature,” Poletto said. “As temperatures begin to increase, everything else begins to increase. For fish, the most notable is metabolic rate.” 

When the metabolic rate increases, fish growth also increases. When fish grow rapidly, their need for food naturally increases, yet a food source is not always available for the growing population of the fish. Poletto explained that researchers often pull fish out of rivers that are overly skinny and ill-looking, which can be an indication that warmer temperatures are increasing metabolic rates. Fish are unable to compensate with enough calories to balance out their high metabolism and the lack of food causes weight loss and health issues, Poletto said.

Second, because irrigation is such a key component in Nebraska’s farmland, water level fluctuations are also an issue for fish. 

“As we pull water out of the rivers for irrigation and for municipal use, the water levels begin to drop and fish can actually become stranded,” Poletto said. For example, there are places in the Platte River that go dry and it happens rapidly. When this happens, fish may not have enough time to move to a new area and often become deserted. 

Finally, while pesticides are an important aspect of the farming industry, they may burden fish populations if pesticide levels get too high. Pesticides are maintained at levels that are safe for humans to drink, but fish are much more susceptible to elevated levels. “They [fish] start to show abnormalities in behavior, physiology, growth, so we see that first,” Poletto said.

Being aware of specific stressors that are impacting fish in Nebraska habitats is essential. This knowledge will be a cornerstone of the continuance of fish conservation. 

Jamilynn Poletto in her aquaculture lab with
undergraduate lab manager Octavious Bartek.
Jamilynn Poletto in her aquaculture lab with undergraduate lab manager Octavious Bartek.

Conservation Efforts in Nebraska

Many Nebraska residents are passionate about being outdoors. Hunting, fishing and watching nature are some of the many things in which Nebraskans are interested and contribute to the advantage of being in Nebraska. According to Poletto, some residents inherently want to be around wildlife populations. This often makes people more receptive to the importance of conservation and environmental restorations. 

“I think we need to get the message across that if we don’t continue certain conservation efforts or if we don’t create new conservation efforts, we are going to lose these endangered fish species populations,” Poletto said. 

Moving forward, conservation projects and management will be crucial for species of all ecosystems, but especially for specific fish species because they represent nearly half of the vertebrate diversity that exists in the world. 

“We have this amazing opportunity to study the diversity of fish species. For pretty much any physiological property or behavioral property you want to study, there is a fish species that is the shining exemplar of it. Studying fish allows us to continue to look into interesting scientific principles that maybe we can’t study in mammals or in birds,” Poletto said. 

Human love for wildlife will be the drive for people to continue to keep conservation efforts resilient. When people are passionate about something, they typically work hard to keep it and fish need our help, she added. 

“Endangered fish are not going to heal themselves, if we do not help them at this point. There are so many human imposed stressors that we have inflicted upon them,” Poletto said. “It’s important to keep studying them because they are interesting and they provide information that we didn’t previously know.”

Keeping conservation efforts alive will help maintain the resilience of these species that are constantly faced with stressors in their environments.

The Future of Fish Conservation

Technological developments to conservation efforts are currently happening at the university. “I think the future of conservation is using technology in really unique and creative ways. That is going to come from students who are studying technology and science right now,” Poletto said.

Poletto’s aquaculture laboratory, located behind the Nebraska Tractor Test Laboratory, is making strides toward stronger fish resilience. Poletto’s aquaculture lab houses recirculating systems where researchers can run tests to learn more about temperature, water quality and oxygen in fish.   

Within this lab, Poletto and her team determine how well fish can swim (and in what conditions), the maximum temperatures that fish can withstand, how well fish are able to grow and survive in certain conditions as well as how fish respond to the stressors outlined previously. Together, this research helps to understand fish behavior in certain conditions as those same conditions may also impact humans. 

“We rely on the same natural resources that many of the fish and wildlife rely upon,” Poletto said. “If they’re not taken into consideration, we’re not taking our own future into consideration as well.”