Lakes and ponds are notably vulnerable to water quality issues; many are damaged by eutrophication in particular. Nevertheless, pond habitats support two thirds of freshwater species.
It is not only permanent ponds that are valuable to wildlife; temporary ponds support specialist species, often rare, adapted to the transient nature of their habitat.
Since 2007, ponds of high ecological quality have been defined as a UK Biodiversity Action Plan (BAP) Priority Habitat. Targets for pond conservation aim to maintain and expand both the extent and quality of ponds of Priority Pond status.
A pond may achieve this status if it is a habitat of high conservation importance, supports species of high conservation value, supports an exceptionally species-rich assemblage, is categorised as being of high ecological quality, or is of limited geographical distribution.
Lakes and ponds may be surveyed using a variety of nets, grabs and dredge to survey benthos, nekton and or plankton.
The ecological quality of a pond is assessed using PSYM (Predictive System for Multimetrics) methodology. This single season survey uses selected environmental parameters, aquatic and wetland plants, and aquatic macroinvertebrates to assess the overall quality of the waterbody.
National Pond Survey (NPS) methodology uses a combination of environmental parameters, plant and macroinvertebrate species data, collected over three seasons, to provide a detailed assessment of a site.
PSYM analysis is used to categorise pond ecological value; whether a pond achieves criterion 4 for priority status.
Species Rarity Indices (SRI) provide a conservation value of a pond based on species-richness and the presence of uncommon species of wetland plant and aquatic macroinvertebrate.
The conservation value of the pond or lake fauna can be assessed using species richness and diversity indices and the Community Conservation Index (CCI).