Background: The management of water in urban areas can be a problem, because rainfall rapidly runs off impervious surfaces like pavements and roads. This means the water quickly enters rivers and streams, which then flood. City managers reduce the rate at which water enters rivers using stormwater management facilities, which often include ponds to hold back the stormwater. These ponds are usually managed just for water retention, but they could potentially form a very useful habitat for aquatic plants and animals in cities.
What we did: We looked at 20 of these stormwater management ponds (SMPs) to see how many animals and plants were using them. We also compared those 20 ponds against 10 other ponds that were not used for stormwater management, but were found in roughly the same area. We showed that the water chemistry in the SMPs was often high in salt, and that the amount of salt in the ponds was related to the amount of urban land cover (which makes sense: much of the salt would have been road salt washed in during snow melt). However, despite some differences in water chemistry there were no significant differences between the SMPs and the other ponds in the diversity of animals. We conclude that it is not the management, per se, that affects the ponds, but the landscape within which they are found.
Importance: Management of particular habitats frequently has to prioritise one function over another. Stormwater management is a major concern in many areas, and so there may not be much willingness to detract from the role of ponds in managing run-off in order to benefit biodiversity. We showed that this may not be necessary: if the ponds are in a relatively low-intensity urban area then they may contain high biodiversity regardless of management.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Stormwater ponds can contain comparable biodiversity to unmanaged wetlands in urban areas”, was published in the journal Hydrobiologia in 2014. You can find this paper at the publisher’s website.
Image credit: tpsdave, http://bit.ly/1rb1IKi, Public Domain.