Dig and they will come: Why drastic pond-restoration strategies pay off

Ponds are home to a wide range of aquatic wildlife, such as this beautiful Azure Damselfly, Coenagrion paella. Copyright Jonathan Lewis

Ponds are home to a wide range of aquatic wildlife, such as this beautiful Azure Damselfly, Coenagrion paella.
Image copyright Jonathan Lewis

Sit quietly at the edge of a pond on a warm summer’s day and you’ll be rewarded with an abundant display of wildlife. You’ll see dragonflies hawking in search of prey over a mosaic of brightly coloured water plants, which are in turn visited by a host of bees and other pollinators. Where sunlight penetrates below the water surface, myriads of insect life can be seen; mayflies, damselflies, water beetles, scorpions and snails – many of which spend most of their life underwater in larval stages. Wait long enough, and you might spot a hobby swoop down to snatch a dragonfly in mid-air, a water vole feast on bankside vegetation or a grass snake silently slide across the water surface in search of frogs.

Ponds are a tremendously rich habitat for wildlife. In Britain they are home to 75% of all freshwater species, and research has shown that they support more species – and more unique and scarce species – than rivers, streams, ditches, lakes or reservoirs.

Each red dot denotes a pond lost since 1957. This example over a very small area of Norfolk is a trend seen across Britain

Each red dot denotes a pond lost since 1957. This example for a small area of Norfolk is a trend seen across Britain
Image by Emily Alderton, used under a creative commons license from Ghost Ponds.

Yet, they are a habitat in crisis: 50% of ponds were lost in Britain over the 20th century and of those remaining, 80% are in poor condition. Whilst billions of pounds are spent on river restoration (despite claims from many eminent scientists that such schemes have no or little positive impact on wildlife), ponds are largely shunned by the conservation world. This bias is clearly apparent in international regulations, such as the European Union’s ‘Water Framework Directive’, which legally binds governments to stringent standards for rivers and lakes, but offers no protection for ponds. Likewise, agricultural stewardship schemes in Britain place ponds low in the list of importance.

However, something of a pond revival seems to be occurring. Research at University College London (UCL) is demonstrating that traditional, but largely forgotten, management of ponds can have a profoundly positive effect on wildlife.

Dr. Sayer and his team have been transforming neglected ponds around Norfolk into wildlife hotspots. His method is simple but effective; dig out a proportion of the sludge and remove bankside trees and vegetation, effectively resetting the process of succession1. It’s an inexpensive process and takes only a day or two to complete. This technique is not for the faint-hearted, with completed sites often looking like bomb craters, but nature is resilient and within no time they recover and are buzzing with life once more.

The team at UCL have carefully observed and recorded wildlife both before and after restoration. The results have been quite astounding.

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Sayer’s Black Pit before, during and after restoration. After two years, the pond showed dense growth of Broad-leaved pond weed.
Images by Carl Sayer1, used with permission.

A typical example of the potential of this type of management can be seen at a highly overgrown pond in Norfolk, humorously referred to by Carl’s team as “Sayer’s Black Pit”. Prior to management, no aquatic plants inhabited the pond, only two common species of dragonfly frequented the site and no species of amphibians were recorded. In 2010 management of the site begun and just two years later an amazing transformation had occurred. The team recorded 9 species of aquatic plant, fourteen species of dragonfly, including the nationally rare scarce emerald damselfly (Lestes dryas) and 4 species of amphibian, including the protected great crested newt (Triturus cristatus).

New growth of stoneworts and other aquatic plants in aquaria containing sediment from a pond which was filled-in 45 years ago.

New growth of stoneworts and other aquatic plants in aquaria containing sediment from a pond which was filled-in 45 years ago.
Image by Emily Alderton, used under a creative commons license from Ghost Ponds.

Interestingly, scientists have also found that buried within the sediment of these ponds is a seed bank2, which remains viable for centuries. Furthermore, some of these seeds are from ecologically important and rare aquatic plants, such as stoneworts. Restoring neglected ponds could be an effective way of returning rare and threatened species to our landscapes.

If managed ponds support such significant increases in plant, insect and amphibian life then could they also help other groups of wildlife, such as rapidly declining farmland birds? What about bats, pollinators or reptiles? Further research will determine whether this is the case, and help to raise the profile of these overlooked gems hidden within our countryside.

A recent survey recorded 21,222 ponds in Norfolk alone3. A majority are overgrown and currently support little diversity. Imagine the benefits to wildlife if these large aquatic networks were restored. Could they act as stepping stones, allowing species to move freely within a landscape? Could they restore the once abundant wetland habitats that existed before damaging activities such as drainage began? Could they improve the resilience of populations, whilst also reversing some worrying declines in British wildlife?

There’s only one way to find out…

References

1. Sayer, C.D., Shilland, E., Greaves, H., Dawson, B., Patmore, I.R., Emson, E., Alderton, E., Robinson, P., Andrews, K., Axmacher, J.A. & Wiik, E. (2013) Managing British ponds – conservation lessons from a Norfolk farm. British Wildlife, 25(1), 21-28.
2. Alderton, E. (2015) Ghost Ponds. [ONLINE] Available at: https://ghostponds.wordpress.com. Accessed 15 December 2015.
3. Carroll (2009) Ponds in Norfolk: Establishing the Feasibility of Determining Important Pond Areas in the County from Norfolk Biodiversity Information Service (NBIS) Data.

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The contribution of managed ponds to avian diversity and abundance on farms in lowland England


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