In our Research Highlights blog series, we debut newly published fisheries research by our women of fisheries colleagues. If you have research you would like to highlight and share with our readers, submit a nomination form here!
This Month’s Research Highlight:
Harrison, S.E., and S.M. Gray. 2024. Effects of light pollution on Bluegill foraging behavior. Transactions of the American Fisheries Society.
Despite only covering approximately 1% of the Earth’s surface, freshwater ecosystems – including lakes, rivers, and wetlands – are home to about one-third of vertebrate species and 10% of all species according to recent estimates. Yet, these ecosystems face a variety of threats, from water pollution to non-native species introductions to climate change. As a result, they are considered the most endangered ecosystems on Earth.
In order to understand the impacts of individual threats on freshwater biota, scientists often conduct controlled laboratory experiments. Susanna Harrison and her team in the Gray Lab and the Streams, Rivers, and Estuaries (STRIVE) Lab at The Ohio State University recently published the results of such an experiment exploring the influence of artificial light at night (ALAN) on Bluegill Lepomis macrochirus feeding behavior. This was part of a larger project funded by the Ohio Department of Transportation to evaluate the effects of roadway lighting on urban freshwater systems and potential solutions to minimize those effects.
Photo Credit: Steven Gratz
Over evolutionary time, fish have adapted and evolved in response to the predicable patterns of light – in timing, intensity, and color – that occur throughout the day and year. However, with the advent of electricity came many anthropogenic light sources from buildings, street lights, and vehicles that ultimately altered these patterns. As human populations continue to increase, these patterns are expected to become even more altered – particularly at night. This ALAN can negatively impact aquatic ecosystems. For example, Susanna notes, “if fish are better able to see potential threats or feeding opportunities at night under artificial lighting, they might become more active and expend more energy than they would under natural dark conditions. This can lead to long-term physiological stress and altered behavior at the individual level (both for the fish itself and its prey), and ultimately scale up to changes at the population, community, and ecosystem levels.”
In their research, Susanna and her team used outdoor tanks to expose hatchery-raised Bluegill to various nighttime light treatments, including constant light at two different light intensities and flashing light at high intensity. These treatments simulated different lighting sources, such as building or street lights (constant) and vehicle traffic lights (flashing). What they ultimately found was that the fish’s feeding behavior was affected by the flashing light, presumably due to light avoidance, yet were relatively unaffected by the constant light. The lack of an effect of constant lighting on Bluegill feeding behavior was surprising but equally valuable to communicate. As Susanna notes, these “insignificant results are important because they seem to contradict expectations based on prior work and they invite further investigation.”
So, no lights out for Bluegill? Not so fast. As with most studies, the answer can’t be found in a single experiment. Additional experiments using wild fish, other species, and other light intensities and frequencies are necessary before any broad-scale conclusions can be made. Although Susanna has moved on from this work, researchers in the Gray and STRIVE labs are continuing with other studies on light pollution, in particular exploring the effects of intermittent lighting.
The negative effects of light pollution are well documented for wildlife – from sea turtles to birds – and much effort has been made to mitigate these impacts. This is a relatively new area of research in fisheries and aquatic ecology, but evidence is building that aquatic ecosystems are impacted as well. Jennifer Schultz with the National Conference of State Legislatures reports 19 states plus the District of Columbia and Puerto Rico currently have laws in place to reduce light pollution. Solutions are relatively simple, including using red light, installing light shields, and limiting hours of operation. Susanna also notes, “one incredibly easy way everyone can limit environmental light pollution is to simply turn off lights at night in and around our homes if they’re not being used. Additionally, timers, dimmers, and motion sensors are all widely available tools that can help individuals reduce their contribution to light pollution (and save money on their power bills).”
So, go ahead. Turn out the lights.
The full manuscript can be found and downloaded here:
doi.org/10.1002/tafs.10451 (open access)
My path was definitely in the “non-traditional” category. I went from art school to the video game industry to the U.S. Coast Guard to an environmental science and ecology degree at UTSA to a graduate fellowship and MSc at Ohio State to my current position with FWC. I guess I would say that my journey is proof that there’s no one “right” way to go about getting involved in research and working in fisheries. If you like science, you’re curious about the natural world, and you’re willing to put in the work, then you are the right person for this type of job. As women, we don’t fit the traditional picture of what a fisheries biologist looks like, so we can face a lot of external barriers to entry into fisheries science- and that goes double for those who fall into any other group that is underrepresented in our field. Unfortunately, we’ll probably always have to fight that battle to some extent, but my advice would be to try not to make it harder on yourself by letting the internal stuff- doubts about your age, comparing yourself to others, impostor syndrome, etc.- hold you back.
Photo Credit: Joshua Jones
