Biotope selection by adult male dragonflies (Odonata) at an artificial lake created for insect conservation in South Africa

Published source details Steytler N.S. & Samways M.J. (1995) Biotope selection by adult male dragonflies (Odonata) at an artificial lake created for insect conservation in South Africa. Biological Conservation, 72, 381-386.
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Summary

A large pond designed to incorporate a range of habitat types (biotopes) at the National Botanical Gardens (30º20’43”S, 29º36’25”E) in the city of Pietermaritzburg (KwaZulu-Natal, South Africa) was created as part of an ecological landscaping urban project for plant and insect conservation. A study was undertaken investigating Odonata colonization and biotope conditions that attracted and maintained them.

The site comprised a stream impounded in June 1989 to form an elongated pond of about 300 m in length and 550 m circumference, retaining an in and outflow of water via the original stream. A range of vegetation was planted or established naturally in the water and along banks. A 3-m high waterfall and rapids were also created.

Between January 1987 and June 1989 the stream section to be inundated was surveyed (about 30 times) for Odonata. After pond creation, surveys were made during walks around the site on 10 occasions during 1-14 February 1991. The pond was divided into 31 plots, each 20 m x 2 m (1 m of bank and 1 m of water); adult male Odonata within each were recorded.

Biotope preference of each species was determined by categorising each plot dependent on percentage of shaded area (at midday), water flow characteristics (pond or stream), and percentage cover of important vegetation.

Twelve Odonata species were recorded before pond creation (5 Zygoptera; 7 Anisoptera) and 26 (11 Zygoptera; 15 Anisoptera) after creation.Only one riverine species, Paragomphus cognatus was lost due to creation of the pond, but it remained abundant along the stream adjacent to the survey area.

Whilst most colonisers were widespread habitat generalist and strong-flying, widely-dispersive dragonflies, some were more local, rarer species including two damselflies, Pseudagrion hageni and Chlorolestes tessellatus, which require woodland along the water’s edge.

Creation of this pond incorporating a wide range of biotopes thus increased local Odonata species richness.

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