Ponds, Pools and Lochans

2.3 Biological importance of ponds


Ponds are often very rich habitats, particularly important for aquatic invertebrates, wetland plants and amphibians. They are also used by a variety of mammals, birds and fish, especially where ponds form part of a mosaic of wetland habitats.

Even compared to other freshwater ecosystems, such as lakes and rivers, ponds are surprisingly rich. For example, comparing river invertebrate data from a 600 site national database collected by the Institute of Freshwater Ecology with a similarly-collected but smaller data set (156 sites) from the National Pond Survey suggests that, at a national scale, small water bodies support: (i) at least as many invertebrate species as rivers and (ii) considerably more uncommon and rare species (see Table 2).

Table 2.
Macroinvertebrate biodiversity in ponds and rivers in Britain. Ponds in Britain support: (i) at least as many invertebrate species as rivers and (ii) considerably more uncommon and rare species.

Invertebrate Groups

Species richness Nationally Scarce spp. Red Data Book spp.
Ponds Rivers Ponds Rivers Ponds Rivers
Flatworms 8 9 1 0 0 0
Snails and orb mussels 34 33 1 2 4 2
Leaches 10 14 1 0 0 0
Shrimps, slaters and crayfish 6 10 0 0 0 0
Mayflies 19 37 0 1 1 3
Stoneflies 7 27 0 1 0 0
Dragonflies 26 13 4 2 1 0
Water bugs 45 27 2 0 1 0
Water beetles 170 100 60 27 13 4
Alderflies and spongeflies 2 3 0 1 0 0
Caddis flies 71 95 3 7 1 4
Total number of species 398 368 72 41 41 13
Sources: National Pond Survey unpublished data: Wright et al. (1996). The comparison is based on all invertebrate groups sampled in both surveys for which reliable published national distribution and nd status are available.
Note: Numbers of taxa given by Wright et al. (1996) in their Table 1 were modified as follows to enable comparisons to be made. Argulus Foliaceus was omitted from the Crustacea total; Sigara (Sigara) sp. was omitted from the  Hemiptera total; water beetles in the family Scirtidae (4 taxa) were omitted from the Coleoptera total; Hydroptilidae (seven taxa) were omitted from the Trichoptera total.

The importance of ponds in supporting rare species is underlined by the number of freshwater UK Biodiversity Action Plan (BAP) species that are found in permanent and temporary ponds. In Scotland, these include: great crested newt (Figure 9), natterjack toad (below), pillwort (Figure 11), slender naiad, marsh clubmoss and medicinal leech. For other BAP species, such as water vole, otter, reed bunting, common scoter and red necked phalarope (Figure 7), ponds may be an important component of the species habitat.

Ponds_fig5.jpg (10782 bytes)

Figure 5. The natterjack toad (Bufo calamita) is Britains most endangered amphibian. In Scotland it occurs in coastal ponds in the south-west. Information on the management of this species is contained in the natterjack toad conservation handbook (Beebee and Denton, 1996). Pond Action

 

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Figure 6. Many damselfly species are found in semi-permanent and temporary ponds, including acid waters, throughout Scotland. Lorne Gill/SNH

 

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Figure 7. Man-made and natural pools are an important component of the breeding habitat of the red-necked phalarope (Phalaropus lobatus) which usually nests amongst flooded peat cuttings or other shallow pools in northern and western Scotland. Chris
Gomersall/ RSPB
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