Sustainable drainage system (SuDS) ponds in Inverness, UK and the favourable conservation status of amphibians

Abstract

Amphibians are suffering global declines in populations, and urban habitats are becoming increasingly important for the survival of several species. Sustainable Drainage Systems (SuDS) in Inverness (Highlands, UK) were studied over 3 years to assess their role in supporting breeding amphibians. Amphibians were found in seven of the 12 SuDS ponds surveyed in 2010 and eight of the same 12 in 2011 and 2012. Of the eight, common frog Rana temporaria bred in every pond and common toad Bufo bufo bred in two of them. Palmate newts Lissotriton helveticus were found in one pond in 2012. Chemical analysis (pH and for ammonia, nitrate, nitrite, phosphate and chloride ions) showed none of the ponds contained pollutants at levels known to have adverse effects on amphibians. Nutrient levels in Inverness SuDS are lower than those found in a previously published sample of lowland British ponds: six of the 12 SuDS ponds had NO3 concentrations <0.5 mg/l N and phosphate <0.05 mg/l P (i.e. below levels which would normally be considered eutrophic). The suitability of SuDS for the nationally scarce great crested newt Triturus cristatus was also evaluated. The Inverness SuDS had higher great crested newt Habitat Suitability Indices than ponds in the wider countryside and exhibited a greater variation in size than previous studies of urban ponds in the UK, which may increase their ability to support a range of species.