The report on the government-funded Lowland Pond Survey conducted in 1996 shows that countryside ponds are being lost at a worrying rate. Between 1990 and 1996, nationally, there was a high turnover of ponds with an estimated net loss of around 2000 ponds. When new ponds were created they were constructed principally for amenity uses such as fishing and wildfowling. More than one third of the ponds identified in the survey were seasonal and were dry in the Summer of 1996. Of the remaining ‘permanent’ ponds more than 40% were very shallow, having an average water depth of less than 25cm. A map study in Hertfordshire during 1986 revealed that in 100 years the total number of ponds in the county had almost halved. In the same year a field study of 730 ponds showed that 80% were in poor condition (The Hertfordshire Pond Report 1987).
As a monitoring exercise during the summer of 1997 a repeat survey was performed on a sample of these ponds. Macroinvertebrates, fish, amphibians and birds were recorded as well as marginal, emergent and submerged/floating vegetation. Physical features including size and depth, management style, origin and condition were also recorded. Ponds were subsequently scored using the Biological Sites Assessment Card for open waters. Of the 59 ponds surveyed, the results showed a substantial loss of water with a corresponding reduction in diversity of aquatic flora and fauna. 17 ponds were completely dry representing 29% of the ponds re-surveyed.
When the same pond quality scoring system used in 1986 was applied to the remaining 42 ponds, the biological quality decreased from a mean score of 24 in 1986 to 19 in 1997; this amounted to a significant 21% decline. The quality of the sample of ponds has clearly declined during the last 10 years and may reflect a similar decline throughout the county. It is important that monitoring programmes are initiated in Hertfordshire to evaluate long-term pond quality trends with respect to pollution and climatic change.
HBRC have decided to carry out a survey across the county to follow-up their results from 1986 and see how quality and diversity of ponds has changed in Hertfordshire in the last 20 years. They will add their results to the National database and their own information records.
Part of my work as Pond Project Officer has been to establish a programme of monitoring in a representative range of ponds across the county, focussing on HCC's 1986 pond survey (top grade ponds) and ponds that are likely to be of biological importance (for example, for protected species). Some of the surveys have also been carried out in association with the Countryside Management Service. We are using three different survey sheets for each pond: the Biological Card for Open Waters looks at general characteristics (such as age, management, pollution, and number of species) to determine a score for each pond. This was used in 1986 and we are using it to give a fair comparison to previous results. We are also using the NPMN basic survey sheet, this notes general characteristics and surrounding land-use. The third survey is the new National methodology: PSYM (Predicitve SYstem for Multimetrics), this has been developed to be a standard across the country. It uses the vegetation and invertebrate species found in each pond, to produce a score. The latter two surveys will be added to the National database.
I have also compiled a pond inventory and created a pond layer in point data on GIS, entering all the ponds marked on the os map, plus any others known about, onto a database. This will make it easy in the future, to find any pond and any information associated with it.
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