The aquatic invertebrate fauna of Ogof Draenen cave system in South Wales, UK

Knight, Lee R.F.D.; Brancelj, Anton; Edwards, Francois; Maurice, Lou. 2018 The aquatic invertebrate fauna of Ogof Draenen cave system in South Wales, UK. Cave and Karst Science, 45 (1). 19-30.

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Abstract/Summary

The invertebrate fauna of the Ogof Draenen cave system in South Wales was investigated between 2012 and 2015. Fifty-nine sites were sampled within the cave, comprising 51 sites on vadose streams, four pools and four dripping avens. The main method employed in vadose streams was three minutes of “kick sampling” using an FBA pattern net. Pools and smaller flows of water were sampled using a combination of netting and manual searching. Sampling was also carried out on the surface at six resurgences and four surface seepages/streams feeding into dolines (stream sinks) that are known from dye-tracing to be connected to the cave system below. Sixty-two invertebrate taxa were recorded in the cave system, 43 from the sinks, and 58 from the resurgences. Most cave samples were dominated by Oligochaeta and stygobiontic Crustacea including the amphipods Niphargus fontanus Bate 1859 and Microniphargus leruthi Schellenberg 1934, the isopod Proasellus cavaticus Leydig 1871 sensu Henry 1970 and the syncarid Antrobathynella stammeri Jakobi 1954. The records of M. leruthi, a species only discovered in Britain in 2010, are the first from a Welsh cave system; and the records of A. stammeri are the first for this species from Wales. Four eustygophilic species were also recorded in the cave, which were not present in samples collected from the resurgences or sinks and may therefore represent isolated subterranean populations. These included: the oligochaete worm Dorydrilus michaelseni Piguet 1913, the ostracod Cavernocypris subterranea (Wolf 1920), the copepod Paracyclops fimbriatus (Fischer 1853) and the halacarid mite Soldanellonyx chappuisi (Walter 1917). The amphipod Gammarus pulex (Linnaeus 1758) occurred in the sinks, resurgences and at several sites within the cave, some at a considerable distance underground, and amongst large populations of stygobiontic Crustacea. These showed varying degrees of depigmentation and were highly likely to represent a eustygophilic population. Stygobiontic Crustacea were common and often abundant, with populations of over 100 Proasellus cavaticus at some sites. In total, 7010 invertebrates were collected from the 59 samples. These samples represent only a tiny fraction of the habitat present, and therefore the invertebrates in the cave system may occur in substantial enough numbers to play a role in biogeochemical cycles. The invertebrate communities of lentic (static water) habitats were less diverse than those of the vadose streams and included small numbers of Oligochaeta, with occasional specimens of P. cavaticus, N. fontanus, Microniphargus and Nematoda, as well as the copepod Paracyclops fimbriatus. Epigean benthic fauna were present in the cave close to surface inlets, and within the surface sinks and resurgences, although the latter were also characterized by stygobiontic Crustacea, including a second Niphargus species, N. aquilex Schiödte 1855, which was not found within the cave. The presence of five stygobiontic Crustacea from the system makes this the most diverse stygobiontic fauna recorded so far from a British cave.

Item Type:	Publication - Article
UKCEH and CEH Sections/Science Areas:	Water Resources (Science Area 2017-)
ISSN:	1356-191X
Additional Keywords:	Ogof Draenen, cave aquatic invertebrates, stygobiontic Crustacea, eustygophilic, biodiversity
NORA Subject Terms:	Ecology and Environment Zoology
Date made live:	27 Jun 2019 14:50 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/523972

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