Notes on Erigone arctica

From The Newsletter No. 89 November 2000

Recently, I have been collecting around disused pits near Lound in Bassetlaw along the Idle valley, mainly by beating, grubbing and some sweeping.

In July 1999, on a very small area (about 6 m2) of shoreline with shingle, in about 10 minutes of searching, I found four females and two males of Erigone arctica (White, 1852). This species is apparently common around all the British coasts, but is far less commonly met with inland.

Roberts (1987) mentions sewage beds and large lakes. To these it seems we can add flooded sand workings where these have plenty of shingle at their edge. It would be interesting to know (and perhaps the forthcoming distribution Atlas will clarify the matter) if this habitat is now being routinely colonised by Erigone arctica—windblown no doubt from some stretch of sea coast. Apart from the water being fresh and not salt or tidal, the physical similarities to the seaside are obvious; and there seems no reason why this spider should not thrive inland, given suitable conditions.

In late July our S.R.S. County Organiser, Tom Faulds, and I visited a second site about 2.5 km away down the river Idle. There we chiefly searched a limited area, about 30 m long by 2 m wide, beside a large flooded area with shallow water at the edges. The first metre width was sand and shingle with drift-type debris and algae; while clumps of rushes, thick grass tufts in hollows, and low herbage characterised the vegetation further back from the water. Only one male Erigone arctica was found in the shingle on this occasion but, interestingly, another widespread but uncommon species turned up in this niche: two males and one female of Prinerigone vagans (Audouin, 1826), found mainly in sewage beds and 'wet grassy habitats' (Roberts, 1987; Locket & Millidge, 1953) or salt flats (Locket & Millidge, 1953).
 
Added by John Partridge at 17:49 on Sun 8th Jan 2012.

INLAND RECORDS OF ERIGONE ARCTICA (WHITE) by Eric Duffey

From The Newsletter No. 23 December 1978

This small Erigonid spider is well known as a coastal species in Britain, occurring in the driftline on sandy beaches and also on salt marshes. It is probably widespread around the whole of the British coastline, and sometimes occurs in very large numbers (Locket, Millidge, Merrett 1974 map 484). It is generally confined to the limits of the inter-tidal range, but may avoid flooding by seawater for long periods because it is often found under driftline material or scattered vegetation at the extreme upper limit of the tide (van Wingerden 1977). On the Suffolk coast I have taken it on brackish marshes on the landward side of the coastal dunes, where the water level fluctuates only slightly in relation to the tidal level. These brackish lagoons may become almost fresh during periods of high rainfall.

Although it is unusual to find Erigone arctica above the extreme point of highest tides, and I personally do not have any records of it occurring for example in the marram dunes on coastal sites in England and Wales, it may extend further inland in parts of Scotland. In the Outer Hebrides and north-west Scotland, large numbers of Erigone arctica have been taken on the machair where the vegetation is extremely short (for example heavily grazed turf) sometimes as far as 300 metres from the shore-line. In addition Dr. W.S. Bristowe tells me that, in the early 1930s he took a specimen on top of the highest hill on the main island of Orkney. Nevertheless, well-established inland colonies of this spider are confined to the very specialised habitat of sewage filter beds, where it has been frequently recorded on the spaces between the clinker. Many of these records come from the Midlands, particularly the numerous sewage farms around Birmingham (Duffey 1978).

It seems strange, however, that a spider which is so widespread around our coasts and is a very good aeronaut should not be taken in other inland situations in this country. It is known to be, for example, widespread on mountains above the tree-line in Scandinavia and Iceland, on stony bare ground, but is has not been recorded in this habitat in Scotland or further south in Europe. The presence of this species on sandy inland heaths in this country, where one might perhaps expect to find it, has never been proved, although a good deal of work has been done on such areas by British arachnologists.

In N. Germany it has been recorded from inland saline areas and Professor Vlijra of the Free University, Amsterdam, in the Netherlands, tells me that specimens have been taken on the sandy foundations of building sites in that city. The saline areas of Cheshire may be similar to those in Germany although those surviving today are artificial and consist of saline lime beds and areas of salt-contaminated land and waste material from salt works (Lee & Greenwood 1976, Lee 1977). These areas vary very much in their salinity and also in the type of vegetation which colonises them. On 12th July 1978, a visit was made to the Witton lime beds just outside Northwich, Cheshire (N.G.R. SJ 663746) during the British Ecological Society summer meeting. Northwich is the main centre for tho salt industry in Britain, and around it is a complex of sites varying in area and the chemical nature of their waste material. At the Witton beds, a collection of spiders was made by sweeping open grassy vegetation on 2 different sorts of lime beds which have a base status of pH 12. In one case, the bare ground cover was about 40% and there was a thin, scattered growth of grasses and a few other herbs. In the other, the vegetation was better developed, with about 25% bare ground and a more diverse herb layer, with numerous scattered bushes, particularly of willow. On the day of the visit, the ground was dry and hard, but there were areas on the beds which clearly became waterlogged during periods of wet weather. The collection of spiders (made by the use of a sweep net for about one hour) included species which are common and widespread in Britain, but also one male of Erigone arctica. As it was on the upper parts of the vegetation it was, presumably, about to disperse aerially, the weather being very favourable at the time. As far as I am aware, this is the first inland record for this species in Britain away from sewage filter beds. In contrast collections also made on 12th July from wet saline marshes at Sandbach and Winsford in Cheshire produced only 2 female Erigone longipalpis (together with several common species) as evidence of association with coastal salt marshes.

The purpose of this note is to draw attention to this new habitat for E. arctica, and to ask whether other members of the Society have inland records in similar or different types of situation. If such exist, I would be very pleased to have full details including date, place and particularly the nature of the vegetation and type of substrate on which the spiders occurred. I would also like to have similar records from other countries in Europe in order to find out whether this species is widespread in other types of habitat further south in its range. In 1975 I made extensive collections around inland saline lagoons near Zarargossa in Spain but did not record E. arctica.

References:

Duffey, E. 1975. Habitat selection by spiders in man-made environments. Proc. 6th Int. Arach. Congress, pp 53-67. Amsterdam.
Lee, J.A. 1977. The vegetation of British inland salt marshes. J. Ecol. 65(2) pp 673-398.
Lee, J.A. and Greenwood, Barbara. 1976, The colonisation by plants of calcareous wastes from the salt and alkali industry in Cheshire, England. Biol. Conserv. 10(2) pp 131-149.
Locket, G.H., Millidge, A.F. and Merrett, P. 1974. British Spiders, Vol. III. Ray Soc. London.
Van Wingerden, W.K.R.E. 1977. Population dynamics of Erigone arctica (White). Ph.D. Thesis. Vrije University, Amsterdam.
 
Added by John Partridge at 17:45 on Sun 8th Jan 2012. Return to Summary for Erigone arctica