**5. Ice age refugia of temperate forest steppe and steppe gastropods: The results of quaternary malacological investigations on the loess/ paleosol sequence of the Crvenka brickyard, northern Vojvodina, Serbia**

its Atlanto-Mediterranean vicariant counterpart: *Pomatias elegans*. The radiocarbon-dated appearance of these latter taxa in the Ócsa profile is the oldest recorded one in Europe several thousand years before the first Atlantic distribution records of the taxon [98, 99]. On the basis of this record, the assumption that the Atlantic and Central European distribution of this taxon is connected to the Middle Holocene [100] must be refuted. The appearance of *Pomatias* 

Bátorligeti marshland, Bátorliget Fényi-forest, and Vámospércs Jónás region.

104 Biological Resources of Water

**Figure 5.** The European distribution of *Pomatias elegans* and *Pomatias rivulare* and their Hungarian fossil, pre-modern and modern occurrences. Horizontal black line = European distribution of *Pomatias elegans*; vertical black line = European distribution of *Pomatias rivulare*; white cross = Hungarian Pleistocene distribution of *Pomatias elegans*, Vértesszőlős, Tata, and Budai Várhegy; white stars = Hungarian modern distribution of *Pomatias elegans*, Bérbaltavár, Tihany, Őrtilos, Zákány, and Zákányfalu; white circle = Hungarian Holocene distribution of *Pomatias elegans*, Szurdokpüspöki, Esztergom, Budapest— Rákos-patak, Ócsa, Kiskörös, Fehérvárcsurgó, and Keszthely—Fenékpuszta, Kisapáti, Tapolca, Celldömölk, Ménfőcsanak, Balf, and Fertőboz; white pentagon = modern Hungarian distribution of *Pomatias rivulare*, Bátorligeti marshland, Szekszárd Sötét-valley, and Nagymányok; white rectangle = Hungarian Holocene and subrecent distribution of *Pomatias rivulare*,

> The findings of Quaternary mollusk analyses implemented on radiocarbon-dated loess/paleosol sequences from the eastern half of the Carpathian Basin in the 1980s have clearly revealed that the Late Pleistocene environment of the Carpathian Basin was far from being uniform [54, 55, 64]. These observations gave an impetus to further comparative paleobiogeographical investigations using our malacological records deriving from different parts of the basin and covering the period of the Late Pleistocene. To highlight the environmental conditions characteristic of the southern part of the basin, our findings on the mollusk fauna of a Northern

Vojvodinian loess/paleosol sequence at the brickyard of Crvenka are presented in the following part [69, 104, 105]. The observed features of the malacofauna are in line with the ones made at other loess/paleosol profiles from the Southern GHP, spanning the same time period [54, 55, 67, 68]. A comparative analysis of these profiles with that or Crvenka enabled us to reconstruct the Late Glacial paleobiogeography of the southern part of the basin and tackle the spatial distribution of refugia for temperate forest steppe and steppe gastropod elements. Changes observed in the mollusk fauna of the Crvenka loess/paleosol profile are in line with climatic fluctuations recorded in the NGRIP Greenland ice core. The presence of numerous interstadial horizons representing the Greenland Interstadials between GI17 and GI2 could have been identified (**Figure 6**). The relatively low resolution of sampling hampered the identification of all GI events at the centennial scale. Based on our malacological data, the milder periods were characterized by higher temperatures and decreasing humidity resulting in a fixation and expansion of short grassland vegetation and the accompanying steppe-dwelling mollusk elements, while the cooler periods experienced only a minor drop in temperature and increasing humidity favoring the expansion of high grasses and some arboreal elements (scattered trees and bushes).

This type of change is especially pronounced in the horizon corresponding to the last glacial maximum. During this time an expansion of cold-loving, tundra-dweller mollusks is recorded in the northern and western ice-free areas of Europe. Conversely, this period is characterized by the appearance of closed woodland dwelling mollusks coevally with the coldloving Arcto-Alpine elements. According to the trends observed, the southern parts of the GHP were characterized by fluctuating expansions and retreat of short grass and high-grass grasslands during the warmer and cooler periods of the late glacial. Thanks to the mosaic-like complexity of these habitats, mollusk taxa with contrasting ecological preferences regarding humidity, temperature, and vegetation cover could have existed side by side during the Late Pleistocene. Humidity increases during the coolings favored the expansion of mollusks resulting in a highly diverse fauna. Conversely, the warmer periods creating drier conditions

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This unique feature of the southern part of the Carpathian Basin is by no means a newly described phenomenon. It has been known for ca. 30 years that compositional changes in the mollusk fauna of the southern parts of the basin are utterly different from those recorded in the other parts of the Carpathian Basin as well as in northern, western, and eastern Europe [54, 64, 67, 94, 106]. The most important difference is seen in the constant presence of xerothermophylous grassland elements (*Cochlicopa lubricella*, *Granaria frumentum*, *Pupilla triplicata*, *Chondrula tridens*, and *Helicopsis striata*) during the entire Late Pleistocene and their clear dominance in periods corresponding to the interstadials [67, 69]. It must be noted that the dominance peaks of the individual taxa in different profiles of the Southern GHP may not be fully coeval thanks to variations in local environmental and microclimatic conditions. Yet the general fluctuations of the similar warmth-loving paleoecological groups in time are synchro-

It is also important to note that during the stadials characterized by only small temperature drops, the dominant elements of the mollusk fauna were those of the Holarctic forest steppe and high-grass-steppe dwellers, primarily members of the taxon *Vallonia costata*. During the interstadials, the fauna was prevailed by taxa characteristic of short grass Pontian grassland dwellers, which occupy the central driest Pannonian forest steppes of the Carpathian Basin (*Cochlicopa lubricella*, *Granaria frumentum*, and *Helicopsis striata* paleoassemblage). At the same time, elements of Holarctic forest steppes were also present in the malacofauna, although highly subordinately. Similarly, the Pontian grassland elements were likewise present in the

All these data indicate the presence of an ecotone of temperate Pannonian forest steppesteppe areas composed of highly complex patches of short and high grassland types between 60,000 and 24,000 cal BP years. The recurring macroclimatic changes of the Late Pleistocene controlled a cyclical expansion and retreat of these environmental mosaics [67]. The best indicator element of temperate grasslands is *Granaria frumentum*. The largest aerial distribution of this taxon is recorded during the Late Glacial ca. 60 ka in the Carpathian Basin. During this time the presence of this taxon could have been observed in the areas of the Transdanubian Mid-Mountains in Western Hungary and the Sub-Carpathian alpine region as well besides that of the GHP. This spatial distribution must have developed during the last interglacial

decreased the diversity.

nous between the individual profiles [67, 69].

mollusk assemblages of the stadials.

**Figure 6.** Fluctuations of different palaeoecological indicator groups on the late Pleistocene loess/paleosol sequence of the brickyard at Crvenka (northern Vojvodina, Serbia).

This type of change is especially pronounced in the horizon corresponding to the last glacial maximum. During this time an expansion of cold-loving, tundra-dweller mollusks is recorded in the northern and western ice-free areas of Europe. Conversely, this period is characterized by the appearance of closed woodland dwelling mollusks coevally with the coldloving Arcto-Alpine elements. According to the trends observed, the southern parts of the GHP were characterized by fluctuating expansions and retreat of short grass and high-grass grasslands during the warmer and cooler periods of the late glacial. Thanks to the mosaic-like complexity of these habitats, mollusk taxa with contrasting ecological preferences regarding humidity, temperature, and vegetation cover could have existed side by side during the Late Pleistocene. Humidity increases during the coolings favored the expansion of mollusks resulting in a highly diverse fauna. Conversely, the warmer periods creating drier conditions decreased the diversity.

Vojvodinian loess/paleosol sequence at the brickyard of Crvenka are presented in the following part [69, 104, 105]. The observed features of the malacofauna are in line with the ones made at other loess/paleosol profiles from the Southern GHP, spanning the same time period [54, 55, 67, 68]. A comparative analysis of these profiles with that or Crvenka enabled us to reconstruct the Late Glacial paleobiogeography of the southern part of the basin and tackle the spatial distribution of refugia for temperate forest steppe and steppe gastropod elements. Changes observed in the mollusk fauna of the Crvenka loess/paleosol profile are in line with climatic fluctuations recorded in the NGRIP Greenland ice core. The presence of numerous interstadial horizons representing the Greenland Interstadials between GI17 and GI2 could have been identified (**Figure 6**). The relatively low resolution of sampling hampered the identification of all GI events at the centennial scale. Based on our malacological data, the milder periods were characterized by higher temperatures and decreasing humidity resulting in a fixation and expansion of short grassland vegetation and the accompanying steppe-dwelling mollusk elements, while the cooler periods experienced only a minor drop in temperature and increasing humidity favoring the expansion of high grasses and some arboreal elements

**Figure 6.** Fluctuations of different palaeoecological indicator groups on the late Pleistocene loess/paleosol sequence of

(scattered trees and bushes).

106 Biological Resources of Water

the brickyard at Crvenka (northern Vojvodina, Serbia).

This unique feature of the southern part of the Carpathian Basin is by no means a newly described phenomenon. It has been known for ca. 30 years that compositional changes in the mollusk fauna of the southern parts of the basin are utterly different from those recorded in the other parts of the Carpathian Basin as well as in northern, western, and eastern Europe [54, 64, 67, 94, 106]. The most important difference is seen in the constant presence of xerothermophylous grassland elements (*Cochlicopa lubricella*, *Granaria frumentum*, *Pupilla triplicata*, *Chondrula tridens*, and *Helicopsis striata*) during the entire Late Pleistocene and their clear dominance in periods corresponding to the interstadials [67, 69]. It must be noted that the dominance peaks of the individual taxa in different profiles of the Southern GHP may not be fully coeval thanks to variations in local environmental and microclimatic conditions. Yet the general fluctuations of the similar warmth-loving paleoecological groups in time are synchronous between the individual profiles [67, 69].

It is also important to note that during the stadials characterized by only small temperature drops, the dominant elements of the mollusk fauna were those of the Holarctic forest steppe and high-grass-steppe dwellers, primarily members of the taxon *Vallonia costata*. During the interstadials, the fauna was prevailed by taxa characteristic of short grass Pontian grassland dwellers, which occupy the central driest Pannonian forest steppes of the Carpathian Basin (*Cochlicopa lubricella*, *Granaria frumentum*, and *Helicopsis striata* paleoassemblage). At the same time, elements of Holarctic forest steppes were also present in the malacofauna, although highly subordinately. Similarly, the Pontian grassland elements were likewise present in the mollusk assemblages of the stadials.

All these data indicate the presence of an ecotone of temperate Pannonian forest steppesteppe areas composed of highly complex patches of short and high grassland types between 60,000 and 24,000 cal BP years. The recurring macroclimatic changes of the Late Pleistocene controlled a cyclical expansion and retreat of these environmental mosaics [67]. The best indicator element of temperate grasslands is *Granaria frumentum*. The largest aerial distribution of this taxon is recorded during the Late Glacial ca. 60 ka in the Carpathian Basin. During this time the presence of this taxon could have been observed in the areas of the Transdanubian Mid-Mountains in Western Hungary and the Sub-Carpathian alpine region as well besides that of the GHP. This spatial distribution must have developed during the last interglacial (MIS 5), when this taxon expanded to almost all areas of Central Europe, including the Czech Basin [107], the Vienna Basin [108], as well as the Alps and the Carpathian Mts to a height of ca. 1000 m ASL [25, 26, 109]. All these indicate the expansion of temperate forest steppes to the foothill areas and the lower highlands during the drier periods of the last interglacial characterized by higher temperatures as well. After 60 ka, marking the onset of the last glacial, there is a gradual retreat in the distribution of *Granaria frumentum* to scattered habitats characterized by favorable microclimatic conditions. There is another major expansion of the referred taxon which can be dated between 40 and 30 ka. The highest dominances are recorded in the southern parts of the GHP with gradually decreasing northward trends. There is a major retreat between 30 and 24 ka to scattered refugia found in the southern part of the Carpathian Basin again, which hallmarked the start of the coldest phase of the last glacial. According to the findings of comprehensive studies done using our own mollusk data compiled into a database (Hungarian Quartermalacological Database), the southern part of the GHP, including the area of Vojvodina, Serbia, as well, was a transitional fluctuation zone between the refugia of the southern foothills of the Carpathians, the marginal area of the Dinarides and its northern island hills. This zone harbored an ecotone of temperate Pannonian grassland and forest steppe during the warmer, drier periods of the Late Pleistocene. Conversely, this vegetation complex was replaced by a boreal forest steppe during the cooler periods, similar to the taiga steppes of Southern Siberia today. This special evolution of the vegetation is utterly different from that of the northern parts of the Carpathian Basin as well as Northern, Western, and Central Europe. The difference is attributable to the regional and local higher temperatures of the ice age resulting in drier conditions in the former areas. Thus the most important ecological driver, regarding the evolution of both the vegetation and the mollusk fauna, in the southern areas of the basin was humidity. The higher aridity of this area during the Late Glacial is attributable partly to the high distance from the seas and oceans. In addition, the intensification of the so-called basin effect as a result of the uplift of the surrounding mountains.

**Acknowledgements**

"ICER."

**Author details**

Debrecen, Hungary

**43**:652-666

1852. 250 p

International. 2016;**415**:241-252

**References**

Pál Sümegi1,2, Sándor Gulyás<sup>1</sup>

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The research was supported by the European Union and the State of Hungary, cofinanced by the European Regional Development Fund in the project of GINOP-2.3.15-02-2016-00009

, Katalin Náfrádi<sup>1</sup>

Ice Age Terrestrial and Freshwater Gastropod Refugia in the Carpathian Basin, Central Europe

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\*, Dávid Molnár<sup>1</sup>

3 Department of Aquaculture, Szent István University, Gödöllő, Hungary

1 Department of Geology and Paleontology, University of Szeged, Szeged, Hungary 2 Archaeological Institute of Hungarian Academy of Sciences, Budapest, Hungary

5 Department of Evolutionary Zoology and Human Biology, University of Debrecen,

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4 Hortobágy National Park Directorate, Debrecen, Hungary

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