Dragonflies as Ecological Indicators

By Wade Boys

Water quality is becoming ever more important to monitor considering the rates of human alterations and climate warming to our landscapes. Aquatic invertebrates are unique organisms that can be used to assess the health of different freshwater habitats. The most common aquatic invertebrates used in this manner include mayflies, stoneflies, and caddisflies. Dragonflies are currently not included in many water quality indices since they are often missed in common collection techniques and are generally more tolerant of pollution than other aquatic insects. However, these beautiful insects can also serve as indicators of habitat stability of different water bodies. 

Dragonflies are in the order Odonata, which also includes their smaller counterparts – damselflies. These insects spend the majority of their life as aquatic nymphs in a variety of freshwater habitats, from lakes and ponds to flowing rivers to small seeps and springs. In fact, a dragonfly may spend up to 3-5 years in the water before they crawl out and emerge as adults! This complex life cycle makes them particularly useful in assessments of freshwater habitats. 

Additionally, dragonflies play an important role in aquatic food webs and are incredible predators both as nymphs and adults. They feed on smaller insects, even those that are more frequently assessed in water quality studies. A unique characteristic of dragonfly and damselfly nymphs is their lower lip or labium, which they shoot out to capture prey! For dragonflies to grow large enough to crawl out of the water and emerge as an adult, they need to have a stable source of prey. Though they are voracious predators, dragonflies are also prey for many other organisms such as fish, birds, and amphibians. Therefore, a diverse dragonfly assemblage is often a reliable indicator of ecological stability.  

Next time you’re near a body of water keep an eye out for these amazing insects! To learn more about the dragonflies in your area, check out Odonatacentral.org. You can contribute to this wonderful resource by uploading records of any dragonfly or damselfly you see. By contributing to this database, you can help track changes in dragonfly and damselfly assemblages which is incredibly important for understanding aquatic habitat health and stability. Happy dragon hunting! 

Wade Boys is a master's student studying ecology and evolution at the University of Arkansas. He is passionate about preserving aquatic habitats and species that rely on them. Learn more about his work at wadeaboys.weebly.com

Pictured left to right: An Ebony Jewelwing damselfly (Calopteryx Maculata.  A Halloween Penant (Celithemis eponina).  A Common Baskettail (Epitheca cynosura) emerging as an adult. 

Photos courtesy of Kevin Mouser and Wade Boys

Join Chert Glades Master Naturalists and discover some nymph dragonflies and other tiny water critters that reside in our streams. We will conduct a biological water quality demo at 12:00, April 27th, at the Earth & Arbor Day celebration in Landreth Park. We are looking for Wonderful, Wacky Water Critters. Join us at creekside and learn what they can tell us about our water quality.

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Posted on April 24, 2019 and filed under NATURAL HAPPENINGS, EDUCATION, EVENTS.