Ground-living spiders ( Araneae ) at polluted sites in the Subarctic

Spiders were studied around the Pechenganikel smelter combine, Kola Peninsula, north-western Russia. The average spider density was 6-fold greater and the density of Linyphiidae specimens 11.5-fold higher at slightly polluted sites, compared with heavily polluted sites. Altogether, 18 species from 10 families were found at heavily polluted sites, the theridiid Robertus scoticus clearly dominating (23.3 % of identifiable specimens), also Neon reticulatus (9.6 %), Thanatus formicinus (9.6 %) and Xysticus audax (8.2 %) were abundant. The most numerous among 58 species found at slightly polluted sites were Tapinocyba pallens (18.5 %), Robertus scoticus (13.7 %), Maso sundevalli (9.5 %) and Alopecosa aculeata (8.2 %). The family Linyphiidae dominated at slightly polluted sites, 64 % of species and 60 % of individuals; compared with heavily polluted sites, 23 % and 38 % respectively.

In the late 1980's, reports of heavy pollution loads from the Russian smelters in the Kola Peninsula and their possible effect on needle losses among pine in northern Finland prompted active studies on effects of pollution on forest ecosystems in northern Finland, Russia and Norway (see KOZLOV et al. 1993, TIKKANEN & NIEMELÄ 1995).
Spiders, like some other predatory arthropod groups, have been observed at heavily polluted sites near smelters in northern Europe (BENGTSSON & RUDGREN 1984, KONEVA 1993, KOPONEN & NIEMELÄ 1994, KOPONEN & KONEVA 2006).Generally, markedly high concentrations of heavy metals have been found in spiders near pollution sources (BENGTSSON & RUNDGREN 1984, KOPONEN & NIEMELÄ 1995, MAELFAIT & HENDRICKX 1998), and spiders have often been used as indicators in monitoring the effects of pollution (e.g.CLAUSEN 1986).In the present paper, information will be given on spider assemblages near the Pechenganikel smelter complex, in the subarctic Kola Peninsula, NW Russia.
For general data on the nature and degree of pollution in the area, see KOZLOV et al. (1993KOZLOV et al. ( , 2009) ) and NORWEGIAN POLLUTION CONTROL AUTHORITY (2002).Spider densities near the Pechenganikel smelter have been briefly dealt with by KONEVA & KOPONEN (1993).For the spider fauna of natural forests in the subarctic and northern boreal taiga zones in Fennoscandia, see e.g.KOPONEN (1977, 1999) and RYBALOV (2003).

Material and Methods
The present study area, the Pechenganikel smelter combine (Nikel and Zapolyarny), ca 69°30'N, 30°20'E, is situated in a subarctic pine forest area, where there are also birch woods, bogs and treeless fells (Fig. 1).The altitude of sites varies between 100 and 200 m asl.The smelter is very close to Norway (only about 10 km from the border) and to Finland (40 km from the border), and the distance to the Arctic Ocean is about 50 km.The yearly mean temperature is about -1°C, and permanent snow cover lasts 6-7 months.
Yearly emission in 1990, just before the spider sampling, was about 250 000 tons SO 2 , ca. 200 tons Cu, 300 tons Ni and 10 tons Co (see KOZLOV et al. 2009).This means that sulphur load was the same as in Monchegorsk smelter, central Kola Peninsula, but copper, nickel and cobalt loads were only 10 % of that in Monchegorsk.The area of complete damage to forests was 45 km 2 and severe damage 300 km 2 around the Pechenganikel complex; in these areas SO 2 concentration was over 80 g/m 3 , and annual dry sulphur deposition ca 4 g/m 2 (GYTARSKY et al. 1997, NORWEGIAN POLLUTION CONTROL AUTHORITY 2002).
Spiders were collected at five study sites in heavily polluted areas, 2.5 -7 km from the smelter, and at nine sites in slightly (or moderately) polluted areas, 6 -55 km from the smelter.The average cover of ground and field layer vegetation indicates the degree of pollution: 30 % coverage at heavily and 80 % at slightly polluted sites.Thus heavily polluted sites are more open and because the ground is often black, their microclimatic conditions in summer are more extreme, i.e. they are drier and warmer than at slightly polluted sites.
Ground-and soil-living spiders were collected, in 1991-92 from 25 x 25 cm squares by hand-sorting.The field work was done by Dr. Galina G. Koneva (Moscow) and identification was by the author.The material consists of ca 620 identifiable spider specimens (of the total 1185 individuals) and is deposited in the Zoological Museum, University of Turku, Finland.
Altogether, 18 and 58 species of spiders were caught in heavily (5 sites) and slightly (9 sites) polluted areas, respectively.Interestingly, as many as 10 families but only 18 species were found at heavily polluted sites, and at slightly polluted sites the material was much more species-rich, but represented no more than 13 families.1).
The dominant species of the slightly polluted sites, Tapinocyba pallens, was found at the heavily polluted sites but only in small numbers.About 64 % of all species and 60 % of specimens at slightly polluted areas belonged to the family Linyphiidae.Three linyphiids were among the six most abundant species.The percentage of Lycosidae was 12 % of all individuals caught (Table 1).

Discussion
Leg deformations or other injuries caused by pollution, could not be found in spiders collected at the polluted sites.Deformations have been observed previously in, e.g., oribatid mites near a smelter (EEVA & PENTTINEN 2009).
The average spider density (about 120 ind./m 2 ) at slightly polluted sites was of the same magnitude as found previously in natural northern boreal or subarctic forests (e.g.KOPONEN 1977).Also the species composition and the great proportion of Linyphiidae among species and specimens in slightly polluted areas resembled the situation in natural forest habitats.The family Linyphiidae is known to dominate in the ground layer of northern areas (e.g.KOPONEN 1993).Proportions of Lycosidae specimens were almost equal and rather low at heavily and slightly polluted sites, i.e. 11 % and 12 %, respectively.In southern Finland, Xerolycosa and Alopecosa species dominated at the most polluted sites near a smelter (KOPONEN & NIEMELÄ 1994).On the other hand, lycosids were not found in the eroded industrial barren area close to the Monchegorsk smelter, central Kola Peninsula (KOPONEN & KONEVA 2006).However, different collecting methods, pitfall traps in southern Finland and hand-sorting both in Pechenganikel and Monchegorsk, must be borne in mind.
When spiders along a pollution gradient were studied by KOPONEN & KONEVA (2006) near the Monchegorsk smelter complex, Robertus scoticus and Agyneta gulosa were also found there in the most polluted areas (black, dead barren sites 2.5-5 km from the smelter).In addition to these two species, only Steatoda phalerata occurred at the most polluted sites.S. phalerata was not found in the Pechenganikel area at all; which may have conditions too harsh for this thermophilous species.Of the present species found at heavily polluted sites, Micaria alpina, Alopecosa aculeata, Evarcha falcata and Tapinocyba pallens were caught in good numbers at rather heavily polluted sites in Monchegorsk (10 km from the smelter).The spider densities near the Monchegorsk smelter were lower than in the present study area (KOPONEN & KONEVA 2006), probably indicating the effect of much greater copper and nickel emissions at Monchegorsk (see Material and Methods).
Emissions of heavy metals and especially sulphur dioxide have decreased greatly since the field work of this paper.According to KOZLOV et al. (2009), the decrease in emissions from 1985 (heavy pollution period) to 2005 was for SO 2 about 70 %, Co 75 %, Cu 20 %, and Ni 15 %.However, pollution in the study area has continued all the time, and emissions at the beginning of this century were still above the critical level for sensitive biota (NORWEGIAN POLLUTION CONTROL AUTHORITY 2002).Thus the environment for the ground-living fauna is nowadays not better than in the early 1990s.

Table 1 :
Composition of the spider fauna in the studied heavily (5 sites) and slightly polluted areas (9 sites), Pechenganikel.

Table 2 :
Total number of spider specimens found at five most polluted and damaged sites (2.5 -7 km from the smelter), Pechenganikel.Agyneta gulosa were found in good numbers at slightly polluted sites.Altogether, four linyphiid species (i.e., Agyneta gulosa, Scandichrestus tenuis, Tapinocyba pallens, and Walckenaeria antica) were found among the total 18 species (22 %) at heavily polluted sites.Only one linyphiid was among the six most abundant spider species (Table2).The percentage of Lycosidae specimens was about 11 % (Table

Table 3 :
Total number of specimens of the most abundant spiders found at nine slightly polluted sites (6 -55 km from the smelter), Pechenganikel.