Hypogean macro-Crustacea records

Quality Control

The dataset has been maintained on an ad-hoc basis since its first creation in 2003. An extensive review of the dataset and up-dating of records was carried out in early 2007. In early 2008 an attempt was made to try and match some of the older records with more accurate dates and grid references (especially the Irish records) by re-checking literature sources and examination of Ordnance Survey maps.

As the dataset only covers a small group of species, a fairly high level of confidence can be attached to the accuracy of the identifications, especially since certain Niphargus species tend to occur in certain areas / habitats and any confusing records have since been checked. There are a few old records for N. aquilex from South wales on the BCRA database which are thought to have been mis-identified N. fontanus and there is some doubt over the correct identification of a record of Crangonyx subterraneus from Montgomeryshire sent in by the Environment Agency. Any doubts over the data have been explained in the Notes section of the database.

Method steps

1. The dataset is built up around a core of data held by the BRC and the biological records of the Cave Research Group (CRG) and British Cave Research Association (BCRA). As the recording scheme is quite small, with few contributors modern records are generated on a rather ad-hoc basis. Methods used in data capture include direct observations underground, trawl nets in pit wells, bait traps, the Gilson well samplers, drift nets for sampling springs and the Bou-Rouch and Karaman-Chappuis methods for sampling the hyporheic zone and springs. Full details of sampling methodologies are included on the scheme website.
   
   Records are included on the database if they are from a known contributor or a specimen is sent to the scheme organiser for validation. A very few old records are thought to be possible mis-identifications and have been corrected and included in the dataset, details of any concern are included in the Notes section. Some records have been generated from literature searches and references are also included in the Notes section.

The dataset covers the whole of the UK (including the Channel Islands) and Ireland, although in the UK the distribution of the hypogean Crustacea is mostly limited to the south of England and Wales (as far north as County Sligo in Ireland). This is thought to be a relic from the last glaciation. Antrobathynella has been recorded as far north as the Midlandian Valley in Scotland and occasional records exist for Niphargus aquilex north of the glacial limit.

Most of the cave systems of the UK have been fairly well covered by the CRG and BCRA recording in the past, which also included some wells and mines. More work is required in North Wales, the Yorkshire Wolds and East Anglia especially. Due to a small number of recorders and difficulties in accessing the habitats in which hypogean Crustacea occur the range of the dataset has limitations. Most modern records reflect the recorders' areas of activity. A few very old records for the Channel Islands exist and a, modern, detailed survey is required. Extensive work has recently been carried out and is still on-going in Ireland.

Most records have eight or six figure grid references, although a few of the older records are limited to 1km or 10km grid references.