MALACOFAUNA OF THE WAWEL HILL IN CRACOW ( POLAND ) – A QUARTER OF A CENTURY AFTER ITS FIRST DESCRIPTION

Mollusc assemblages found at the Wawel Hill in 2011 included 13 species; nine of the species found in 1988 were absent. Several shade-loving species had disappeared and some open-country species had increased in abundance at the expense of others. For example, Vallonia pulchella (Müll.) was a dominant component of the present malacofauna, while V. costata (Müll.) decreased in abundance. The results confirmed the environmental changes that had taken place since 1988: the negative impact of mass tourism and pollution.


INTRODUCTION
The Wawel Hill is located in the centre of Cracow at an altitude of 228 m a.s.l.It is built of Jurassic limestones which were uplifted during the Miocene as a tectonic framework.The hill rises above the Vistula River.Its slopes are mainly covered with planted grass; the eastern, southern and north-western slopes are partly wooded.The southern slope above the Dragon Cave is rocky.On the top of the hill, at the Wawel Castle, flowerbeds have been created.Though the limestones offer favourable gastropod habitats, the considerable air and soil pollution as well as increased traffic and urbanisation cause environmental changes which may contribute to impoverishment of the mollusc communities.The recently intensified human-induced changes result in destruction of natural habitats on the one hand and emergence of anthropogenic habitats on the other.In such places the malacofauna tends to show a different species composition, compared to the surrounding areas.Research on the malacocoenoses of castles has been conducted for many years in different countries (S.W. ALEXANDROWICZ 1995, JUØIÈ-KOVÁ & KUÈERA 2005a, 2005b).The malacofauna of the Wawel Hill has been described by S. W. ALEX-ANDROWICZ (1988).The aim of this study was an attempt to specify possible changes in the malacofauna between 1988 and 2011.

MATERIAL AND METHODS
Samples containing gastropod shells were taken from nine sites at the Wawel Hill (Fig. 1) in the spring of 2011 from the surface soil layer to the depth of 3 cm.Each sample, taken with a spade and containing soil, empty shells and live individuals, was ca. 1 kg.The samples were washed, and fresh shells and their fragments were extracted.The gastropods were identified using WIKTOR's ( 2004) key.
The samples were taken from the central part of the hill as well as from its northern, eastern, western and southern slopes.Site 1 -partly shaded lawn and flowerbed surrounded by a low limestone wall; the site is located among the buildings of the Wawel castle, at the top of the hill, where the grass is frequently mown and renovation works are still carried out in the courtyard.Site 2 -a smaller lawn and flowerbed situated between the Visitors Center and the castle wall in the western part of the ridge.Site 3 -north-western slope of the Wawel Hill below the castle wall; forested, with strongly polluted soil.Site 4 -north-eastern slope, well insolated and polluted because of the close proximity of the Podzamcze street.Site 5 -south-eastern forested slope and open lawn on a flat terrace; the slope is steep, with a low limestone wall in the middle.Site 6 -sward on the southern slope.Site 7 -southern slope and well insolated lawn above the Berdardyñska Street.Site 8 -south-western slope, above the entrance to the Dragon Cave; this part of the hill is rocky and built of Jurassic limestones, with both sunny and shady places; the site is littered.Site 9 -deforested western slope on the left bank of the Vistula River.
Standard methods of malacological analysis were applied as described by LOZEK (1964), S. W. ALEXANDROWICZ & W. P. ALEXANDROWICZ (2011).The indices of diversity: TDI and ADI (S.W. ALEXANDROWICZ 1987ALEXANDROWICZ , 1999) ) were calculated for the whole fauna.Similarity between the assemblages was analysed using the method described by S. W. ALEXANDROWICZ (1987).The structure of constancy (C) and dominance (D) as well as indices of normalised constancy and dominance (C i , D i ) were also analysed (DOBROWOLSKI 1963, S. W. ALEXANDROWICZ 1987).The earlier data on the malacofauna of the Wawel Hill (S.W. ALEXANDROWICZ 1988) were used for comparison.

RESULTS
The whole analysed material comprised 13 snail taxa (1,030 specimens) (Table 1).The species were divided into three ecological groups: F -shade-loving species, O -open-country species and M -mesophile species with wide ecological tolerance.The number of species per sample ranged from 3 to 9, the number of specimens from 9 to 368.
The material used for comparison (S.W. ALEXANDROWICZ 1988), from the nine samples taken between 1983 and 1985 from the same sites (Fig. 1), included 22 species (7-14 per sample) and 1,559 specimens.This "old fauna" included three types of ).The taxonomic diversity index (TDI), as well as assemblage diversity index (ADI) for the whole material, reached 0.6.The TDI for individual samples varied from 0.5 to 0.7.The values correspond to relatively high diversity which is characteristic of polymictic associations.The mollusc assemblages could be divided in two categories.Poor generalised associations occurred in sites 2, 3, 4, 6 and 7, rich generalised associations were present in sites 1, 5, 8 and 9.

DISCUSSION
The 2011 malacofauna included three shade-loving species, five open-country species and five mesophiles (Fig. 2), while the previous survey revealed six shade-loving species, nine open-country species and seven mesophiles.The MSI spectrum indicates that at present the malacofauna is mainly composed of  The changes in the assemblages in individual sites were as follows.In site 1 the species composition changed completely: no mesophiles were found during the previous survey, but they were frequent in 2011.In site 2 the species composition was unchanged, but the abundance decreased.In sites 3 and 4 the 2011 species list was shorter, but included a previously unrecorded Cecilioides acicula.In site 5 the species composition overlapped with the corresponding sample from the previous survey and it was still the largest sample.In site 6 Vallonia pulchella and Cochlicopa lubrica appeared, as well as one mesophile.In sites 7 and 8 the species composition remained unchanged, but the abundance was smaller.The sample from site 9 included Cecilioides acicula, Pupilla muscorum and Trichia hispida not recorded on the previous occasion.
The ADI values for the earlier survey and for the 2011 samples were the same: 0.6.All the studied assemblages were generalised associations.However, the mollusc assemblages changed and the poorly specialised associations disappeared, as indicated by the TDI values for individual samples.The number of molluscs living in unfavourable habitats increased, making the poor generalised associations richer than before.Moreover, the rich generalised associations were poorer.
The similarities among the assemblages changed since the previous survey (Fig. 3).Three clusters of assemblages could be distinguished in the previous survey (S.W. ALEXANDROWICZ 1988), and only two in 2011.The first group included sites 5, 6 and 8, and corresponded with various ecological conditions (partly shady) on the southern slopes of the Wawel Hill.Its TDI varied from 0.6 to 0.7, and the group was similar to that distinguished before.The second group, which differed from the group distinguished in the previous survey, included sites 4 and 7 and represented generalised assemblages of dry, sunny habitats.
The Wawel Hill with its Jurassic limestones creates favourable conditions for gastropods.However, the increased tourism at the Wawel Castle, combined with its location in the city centre, have a negative impact on molluscs due to pollution, traffic, necessity of regular fertilising and grass mowing.The malacofauna inhabiting the Wawel Hill comprises 13 gastropod taxa.The mollusc assemblages are diverse, reflecting the different habitats on the slopes.The assemblages from sites 4, 5 and 8 show no similarity with the assemblages found during the previous survey.Beside these two groups, four separate assemblages from sites 1, 2, 3 and 9 were distinguished.The species composition and abundance and their changes reflect the environmental changes.The changes in species composition in favour of open-country snails and disappearance of shade-loving ones are especially pronounced, reflecting the prevalence of open habitats.
The unfavourable living conditions have resulted in enrichment of poor generalised assemblages.This may cause further loss of species at the Wawel Hill.The dominant species is now Vallonia pulchella, while the abundance of Vallonia costata has decreased.Cepaea nemoralis, abundant during the previous survey, has mostly disappeared.The abundance of Trichia hispida and Helix pomatia has decreased, which may indicate a further impoverishment of mesophilic and shade-loving fauna.Vertigo alpestris in Poland is regarded as a rare and endangered species.It still inhabits the Wawel Hill and has even increased in abundance.The synanthropes found at the Wawel Hill (e.g.Cepaea nemoralis, Cecilioides acicula, Helicella obvia) may have been imported by humans.
Fig. 1.The Wawel Hill in Cracow, sampling sites: 1-9 -2011, I-IX -1988 Constancy (C) and dominance (D) structure of mollusc assemblages for the samples; S tax -number of species, S spec -number of specimens, C i , D i , TDI and ADI -indices Dsnails.The MSS spectrum shows a high diversity.Compared to the previous survey, the number of shade-loving species has become reduced.Only Alinda biplicata is still present in large numbers while Helix pomatia and Cepaea nemoralis have disappeared.Open-country snails remain dominant, but the abundance of Vallonia pulchella has increased at the expense of Vallonia costata, whereas Pupilla muscorum has become much more abundant.Mesophiles are still represented by Cochlicopa lubrica, but other mesophiles occur in smaller numbers.Vertigo alpestris was abundant (21 specimens) in site 1 (at the top of the Hill); during the previous survey it was found in site 9. Nine of the species recorded during the previous inventory were not found in 2011: Truncatellina cylindrica, Truncatellina claustralis, Cochlicopa lubricella, Vitrina pellucida, Aegopinella pura, Oxychilus draparnaudi, Oxychilus inopinatus, Arianta arbustorum and Cepaea hortensis.Of these only Oxychilus draparnaudi and Arianta arbustorum were abundant; the remaining ones were represented by single or few specimens.In 2011, the most abundant species (> 50 specimens) were: Vallonia pulchella, Pupilla muscorum, Vallonia costata, Helicella obvia, Alinda biplicata and Cochlicopa lubrica.