Survey of the invertebrate communities in Pen Park Hole, Bristol

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Pen Park Hole is an interesting cave in a small outlying outcrop of Clifton Down Limestone on the outskirts of Bristol, one of the few extant examples in Britain of a cave formed by rising thermal groundwaters. The land overlying the cave is urban parkland, but several times in the past proposals for development of this land for housing have been put forward, regardless of the considerable voids below and the geological interest of the cave.  The cave is also the only known location of a cavernicolous population of the blind, colourless shrimp Niphargus kochianus, which occurs in large numbers in the subterranean lake at the bottom of the main chamber.

The latest proposal for development led to a local group of researchers contacting Natural England, which contracted surveys of the geological and invertebrate interest of the cave prior to possible designation as a SSSI. The invertebrate survey recorded a poor diversity terrestrial fauna, but a large and varied population of subterranean aquatic invertebrates. The results of the surveys led to the cave eventually becoming designated as a SSSI, the first example in Britain in which both its geological interest and ‘its community of cave invertebrates’ were cited on the designation and given equal consideration.