This unique public art in Calgary, Alberta shines lights on the Bow River below. All photos are by Lindsey McDonald.
A new city art project was debuted in 2015, perched on the shore of the Bow River in Calgary’s St. Patrick’s Island. Michel de Broin designed Bloom, a 23-meter tall whimsical flower composed of various streetlights that shine on the paths below (photo above). This gorgeous structure was heralded as adding safety to the park by increasing the amount of light available for pedestrians to stroll through at any hour (Ho 2015). Decisions such as these are made to increase our safety, but what about the fish? City planners need to consider implications of light and sound on surrounding ecosystems. Luckily, Bloom has a dimmer switch, but let’s consider in general how we are impacting these often-forgotten ecosystems.
Streetlights - keep us safe,
Avert your gaze on waterways
Fish, come out and play.
Avert your gaze on waterways
Fish, come out and play.
According to Reid et al. (2019) light and sound pollution are an emerging threat to freshwater ecosystems, especially artificial light at night. The number of hours of light during the day and darkness at night can trigger natural responses (Meyer and Sullivan 2013), such as a bat hunting at night when the light is low and they have the upper hand. Or turtle hatchlings that use the cue of distant silhouettes to guide them to the relative safety of open water. When we take away darkness, we mess with their natural rhythm and complicate their lives.
Freshwater ecosystems host a bevy of invertebrates, fish, and plant life. Ecological light pollution can affect foraging behaviours which influences how and when an organism eats (Meyer and Sullivan 2013). Artificial light at night will limit a predator from finding its prey (Longcore and Rich 2004). It’s easy to just think of the prey, and how wonderful it is that she can live another day… however, this is forgetting about food webs and their multiple complex interactions. Changing one critter’s behaviour can inadvertently change other species abundance, throwing an ecosystem out of balance.
Huh?! Cried Mr. Fish,
with a fin cupped to his ear.
“Quiet down, I can’t hear!”
with a fin cupped to his ear.
“Quiet down, I can’t hear!”
Human development brings light pollution, but also noise pollution through motorized boats or seismic exploration. Sound carries further and more efficiently in water than air, meaning that even sounds that may not bother us could become quite a nuisance underwater. Communication between a species can help them locate food, find mates, or avoid danger (Kunc et al. 2016, Cox et al. 2018). There have been measured impacts on fish having difficulties with foraging and schooling and can have fewer offspring or potential hearing loss (Cox et al. 2018). In freshwater ecosystems, fish are among the top of the food chain, reducing their numbers can impact abundance of aquatic invertebrates and plants, having more consequences we can not predict.
Large-scale ecosystem level changes in these aquatic communities have not been extensively studied, meaning we don’t actually know the final consequences of these actions. The result could be ecosystem collapse, or it could be widespread adaptation. We need to study this to avoid potential disaster that we could be causing inadvertently with our human ways.
A pedestrian bridge near the confluence of the Elbow and Bow Rivers in Calgary, Alberta. The bright lights shine on the water below, creating safety for people and uncertainty for the aquatic life. [Photo: Lindsey McDonald]
Oh, bright city lights
Shining on the Elbow River,
Will they dim your glare?
Shining on the Elbow River,
Will they dim your glare?
What can we do?
Most solutions are at the city planning level, but we can all help. Cities can use motion sensors on lights, so that nobody is subjected to constant glare, and use LED lights with less spread focussed away from water. Worldwide there is a push for dark skies, and the Royal Astronomical Society of Canada has been leading the charge at home. In less than twenty years we reduced our light pollution levels by 34% (Cauwels et al. 2014). Calgary changed more than 80% of their streetlighting to more energy efficient LED lights, not only reducing their cost but also reducing the spread of the light to the streets below.
We can reduce recreational light and noise by people powered sports; kayaking, stand-up paddle boarding, and canoeing are quieter and more environmentally friendly ways to access the water. If motorboats are your thing, consider turning down your music so the sound travels less, reducing unnecessary lights, and keeping away from sensitive areas. We can find ways to enjoy recreation without harming our freshwater friends.
Pun intended. Thanks for reading.
References
Cauwels, P., N. Pestalozzi, and D. Sornette. 2014. Dynamics and spatial distribution of global nighttime lights. EPJ Data Science 3:1–26.
Cox, K., L. P. Brennan, T. G. Gerwing, S. E. Dudas, and F. Juanes. 2018. Sound the alarm: A meta-analysis on the effect of aquatic noise on fish behavior and physiology. Global Change Biology 24:3105–3116.
Ho, C. 2015, August 12. Calgary stargazer worried about brightness of new art piece Bloom. https://calgaryherald.com/news/local-news/calgary-stargazer-worried-about-brightness-of-new-art-piece-bloom.
Kunc, H. P., K. E. McLaughlin, and R. Schmidt. 2016. Aquatic noise pollution: Implications for individuals, populations, and ecosystems. Proceedings of the Royal Society B: Biological Sciences 283.
Longcore, T., and C. Rich. 2004. Ecological light pollution. Frontiers in Ecology and the Environment 2:191–198.
Meyer, L. A., and S. M. P. Sullivan. 2013. Bright lights, big city: Influences of ecological light pollution on reciprocal stream-riparian invertebrate fluxes. Ecological Applications 23:1322–1330.
Reid, A. J., A. K. Carlson, I. F. Creed, E. J. Eliason, P. A. Gell, P. T. J. Johnson, K. A. Kidd, T. J. MacCormack, J. D. Olden, S. J. Ormerod, J. P. Smol, W. W. Taylor, K. Tockner, J. C. Vermaire, D. Dudgeon, and S. J. Cooke. 2019. Emerging threats and persistent conservation challenges for freshwater biodiversity. Biological Reviews 94:849–873.
