Besides negatively impacting the reproduction process, circadian rhythms and consumption patterns of aquatic creatures, light pollution can also severely impact the predator-prey relationship in aquatic organisms like aquatic insects. While not all of them might live underwater, most aquatic insects spend a larger part of their lives in water bodies, with only several days or weeks spent airborne after fully maturing. How then might these winged-creatures move if they can’t fly?
Night Drifting of Aquatic Insects
Well, larval aquatic insects are able to move through the process of “drifting”. Drifting involves the insects detaching themselves from one region of stream substrate to another, while intermittently floating with the current (much like this gif of homer simpson below).
However, because the process of drifting leaves these aquatic insects visible to predators who are on the lookout for food, they preferentially drift at night, even to the extent of avoiding drifting on nights where the moonlight is significantly brighter. However, with the brightening of our cities with light fixtures, the dark night is no longer available for the safe drifting of aquatic insects. In this study, aquatic insects located in streams exposed to elevated levels of artificial light are found to experience significantly lower levels of drift rates.
Why It Matters
With that said, what is the significance of decreased drift rates in aquatic insects? Small as they might be, these insects play a vital role to the larger aquatic ecosystem. Firstly, as a larval, these insects make up a significant part of the diet of fish and amphibians. Having grown into adults, they too serve to feed animals beyond the waters such as bats, birds and lizards. The premature consumption of larval-stage insects facilitated by increased light pollution will leave these dependent animals with insufficient food which eventually is bound to adversely impact their growth and population. This video gives a glimpse of the lives of aquatic insects and the role they play in the larger ecosystem (0:00 to 2:52). This illustrates the importance of aquatic insects in the larger food chain.
Besides its role in the food chain, larval aquatic insects serve as natural managers of algae growth, processing algae as well as breaking down dead leaves that fall into water bodies. Without them, water bodies might observe large algae blooms and even eutrophication, causing further damage to the lives living in and surrounding the water body.
The presence of aquatic insects is known to be indicators of good water quality and environmental health. Hence, monitoring and managing their well-being should be a priority, if not for them, then for the multitude of other organisms that it’ll affect!
Till next time!
Trudie
References:
- Ivanova, N. (2013, January 13). Homer Pool Time [Gif]. Dribbble. https://dribbble.com/shots/4096624-Homer-Pool-Time
- Perkin, L. (2019, March 7). A surprising effect of light pollution: It disrupts aquatic insects • The revelator. The Revelator. https://therevelator.org/light-pollution-aquatic-insects/