Comment
Ponds have long been neglected by science, but we can’t afford to ignore these nature hotspots any more, say Jeremy Biggs and PennyWilliams
CONSIDERING they are the world’s most numerous patches of water, it is surprising that ponds are poorly understood. There are millions – possibly billions – of them. Yet for a century or so, scientists have paid them very little attention.
This neglect might not have mattered were it not for increasing evidence that ponds are extremely important habitats for wildlife. Across many landscapes, they are being shown to support more freshwater plant and animal species than rivers or lakes. From microscopic algae to water beetles, aquatic plants, amphibians and water birds, ponds have rich, diverse and distinctive communities with a disproportionate number of rare and endangered species.
Intriguingly, this biodiversity seems to be partly due to the small size of ponds, which allows them to have a wide range of conditions. The community in a shaded pond with clear, tannin-rich water will be very different to that in a nearby seasonal pond made cloudy by grazing animals. Ponds show far greater variation than rivers and streams, as flowing water tends to homogenise water chemistry.
So why have we overlooked such a vital part of the natural world? A key reason appears to be what freshwater scientist John Downing has called “a saliency error”: the cognitive bias we humans have where we tacitly assume that if something is small, it can’t be all that important. Rather than study ponds, biologists in the past typically headed for the largest lake or river they could find.
Most of us also devalue ponds because we assume they are artificial habitats: we look at the human-made examples around us and don’t realise that these waters have a deeply ancient origin. In our new book Ponds, Pools and Puddles, we debunk this idea. Ponds have clearly existed on Earth as long as there has been land and water and the geological record shows they have been a constant presence. The best-preserved evidence of pondlike freshwater communities anywhere in the world is in the Rhynie chert rocks in Scotland, which has traces of Devonian fairy shrimps swimming among stonewort plants 400 million years ago, just as they do today.
The neglect of ponds within freshwat
