A rare lined claspertail flies low over a wetland in Hluhluwe iMfolozi Park. Minutes later a rarer eastern scissortail joins him in the evening light. It’s an uncommon and beautiful sight, so you grab your camera. Little do you know that these small insects are more than just a photo opportunity, but clues to the surrounding environment as well.
A new manual released by two Stellenbosch University researchers has given the dragonfly a new role: freshwater monitor. Manual of Freshwater Assessment for South Africa: Dragonfly Biotic Index written by Professor Michael Samways and Dr John Simaika discusses dragonflies’ relationship to water and their role in determining the quality of it.
According to Samways and Simaika, you can measure the purity of a water source through the presence of dragonflies. Certain species of the insect equal certain levels of water health. But how does this happen? There are 162 dragonfly species in South Africa, each unique and individual from one another. While some species are easily affected by waste and debris, others have the resilience to live in unhealthful conditions such as polluted or soiled water. Therefore, observing a more sensitive species indicates a fresher body of water, while observing a tougher species may indicate a contaminated body of water.
Samways and Simaika’s manual provides photographs and descriptions as well as each species’s threat and sensitivity level, making it possible to identify both the dragonfly and the quality of the surrounding water. And as Professor Samways notes, thanks to dragonfly observation it’s a lot easier to monitor water health: “You do not have to wade into the water to collect samples when you want to do an assessment, but can do so from the reasonable comfort of a streambank or the edge of a dam.” The guide is currently available as a book and CD, and will soon be downloadable for free.
Watching dragonflies is an activity that is accessible to all. According to Professor Samways, “all you need is a good guide, a pair of close-focus binoculars and a sunny day.” So grab some binocs, choose a body of water and see what you can learn from these extraordinary insects.
Samways, M.J. & Simaika, J.P. (2016). Manual of Freshwater Assessment for South Africa: Dragonfly Biotic Index, Suricata 2. South African National Biodiversity Institute, Pretoria.
Are you a fan of dragonflies? Read the article in the Winter 2016 issue of Wild.
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We have the perfect guide to help you identify dragonflies and damselflies. A Guide to the Dragonflies & Damselflies of South Africa by Warwick and Michèle Tarboton describes all 164 species found in South Africa. The guide contains several detailed images for each species, as well as measurements and a distribution map.
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