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

**Ice Age Terrestrial and Freshwater Gastropod Refugia** 

DOI: 10.5772/intechopen.71910

Pál Sümegi, Sándor Gulyás, Dávid Molnár, Katalin Náfrádi, Tünde Törőcsik, Balázs P. Sümegi, Tamás Müller, Gábor Szilágyi and Zoltán Varga Katalin Náfrádi, Tünde Törőcsik, Balázs P. Sümegi, Tamás Müller, Gábor Szilágyi and Zoltán Varga Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Pál Sümegi, Sándor Gulyás, Dávid Molnár,

http://dx.doi.org/10.5772/intechopen.71910

#### **Abstract**

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Thanks to its unique microclimatic, geomorphological , hydrological conditions forming a mosaic-like environment present at all scales, numerous Late Tertiary and Pleistocene warmth-loving gastropod taxa managed to find refugee within the Carpathian Basin during the major-minor cold spells of the Ice Age. This complex system of refugia have been continuously functioning and evolving since the Late Tertiary through the entire Pleistocene and the Holocene. To understand the spatial and temporal evolution of refugia, detailed paleoecological investigations have been implemented, results of which are summed here. The high-grade fractal-like complexity of the environment led to the emergence of a so-called dual refugia, which is a unique feature of the Carpathian Basin. This temporally parallel but spatially differing presence of habitats for taxa of contrasting ecological needs was noted for paleotemperature gradients and temperate woodland and steppe habitat types as well. Furthermore, detailed geological and paleoecological analysis of a small Pleistocene hot-spring fed pond revealed information about the evolution of endemic thermophylous freshwater gastropod taxa within this microrefugia. This chapter is aimed to give an overview of the nature, evolution of temperate terrestrial and freshwater gastropod refugia present in the Carpathian Basin during the Ice Age.

**Keywords:** gastropods, refugia, evolution of mollusk biota, ice age, Carpathian Basin, Central Europe

#### **1. Introduction**

Embraced by the rugged peaks of the Carpathians, Alps, and Dinaride Mts lies the Carpathian Basin covering an area of ca. 300,000 km<sup>2</sup> at the boundary of Central and Southeast Europe

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

(**Figure 1**). During the ice ages, glaciers were strictly restricted to the Alps with only sporadic occurrences in the adjacent Carpathians leaving the entire basin ice-free [1]. Moreover, permafrost was restricted to the northern rim alone [2–4]. Numerous scientific postulations emerged from as early as the late nineteenth and early twentieth centuries, according to which several Late Tertiary and Pleistocene warmth-loving (thermophilous) gastropods could have found refugee within the Carpathian Basin during the major-minor cold spells of the ice age. This proposed system of refugia must have been continuously functioning and evolving from the Late Tertiary through the entire Pleistocene up to the Holocene. Most of these postulations were made about a single member of a gastropod family, whose representatives were widespread in Europe during the Tertiary: the Melanopsidae. This taxon was first reported during the mid-nineteenth century by the Austrian geologist, von Bregrath Franz Ritter Hauer, from a hot-water spring-fed thermal lake (Lake St. Ladislaus, Püspökfürdő) (**Figure 2**) found near the city of Nagyvárad (today Oradea) [5]. It must be noted though that the German natural scientist Phillippi who gave the first taxonomic description of the gastropod taxon *Melanopsis parreyssii* in his seminal volume from 1847 [6] (page 176 and Table 4, Figure 15) mentions Hungary as the type locality and the Austrian naturalist von Mühlfeld as the collector. Unfortunately, not a single word is given about the exact locality or the time and area of von Mühlfeld's visit. No further details on how the specimen described were attained.

Although there is no exact way to prove that the referred specimen was collected from Püspökfürdő (Baia Mai 1, Romania today), this assumption cannot be fully refuted either, as modern occurrences of this taxon are strictly restricted to a single locality, the referred thermal lake, with no others known. The first detailed geological description of the lacustrine deposits and the embedded Melanopsis taxa comes from the Austrian geologist von Heinrich Wolf [7].

His profile, located at the lakeshore, starts with an embryonic humus layer [7]. The lack of a map displaying the exact location, orientation of his work, as well as the environmental changes of the past centuries hampered the later comparative use of his first description. Yet his work is by no means futile as the major geological units identified and described by him were clearly traceable in later works on the lacustrine deposits as well. So, the referred gastropod taxa appear in later publications from the late nineteenth century as well [8]. Despite the promising start, the first detailed presentation on the Quaternary mollusk fauna of Püspökfürdő, including morphological changes observed on the shells of Melanopsidae, was given only in 1890 by the Hungarian amateur naturalist Mihály Tóth on the 25th Congress of Hungarian Medical Doctors and Naturalists held in Nagyvárad (Oradea) [9]. He presented a series of mollusk shells collected via singling from a 2-m-deep profile. In addition, based on the observed variations, he lined up an evolutionary series with numerous members. In his view, the lake harboring the *Melanopsis* taxa is older than the so-called Old Alluvial (presently known as the Holocene epoch). Thus, these gastropods must derive from a Tertiary ancestor, whose descendants managed to survive the cold periods of the Diluvial (Pleistocene epoch). His work is the first presentation of the referred ice age refugia hypothesis in Central Europe. Considering the formerly accepted relatively short time

span of the Pleistocene at ca. 600 Ky [10–11] compared to the modern known value of 2.58 My [12–16], his postulation is rather remarkable considering our modern understanding of

Selyemrét, Ócsa (Danube-Tisza interfluve, Hungary); and (6) brickyard (Crvenka, Serbia).

**Figure 1.** Location of the sites mentioned in this study on the Holdridge-type bioclimatological map of Szelepcsényi et al. [69]: (1) Lake St. Ladislaus, Püspökfürdő-Nagyvárad (Baia Mai 1, Oradea, Romania); (2) Petény rock shelter (Bükk Mts, Hungary); (3) Rejtek rock shelter (Bükk Mts, Hungary); (4) protected marshland, Bátorliget (Nyírség, Hungary); (5)

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speciation and macroevolution.

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(**Figure 1**). During the ice ages, glaciers were strictly restricted to the Alps with only sporadic occurrences in the adjacent Carpathians leaving the entire basin ice-free [1]. Moreover, permafrost was restricted to the northern rim alone [2–4]. Numerous scientific postulations emerged from as early as the late nineteenth and early twentieth centuries, according to which several Late Tertiary and Pleistocene warmth-loving (thermophilous) gastropods could have found refugee within the Carpathian Basin during the major-minor cold spells of the ice age. This proposed system of refugia must have been continuously functioning and evolving from the Late Tertiary through the entire Pleistocene up to the Holocene. Most of these postulations were made about a single member of a gastropod family, whose representatives were widespread in Europe during the Tertiary: the Melanopsidae. This taxon was first reported during the mid-nineteenth century by the Austrian geologist, von Bregrath Franz Ritter Hauer, from a hot-water spring-fed thermal lake (Lake St. Ladislaus, Püspökfürdő) (**Figure 2**) found near the city of Nagyvárad (today Oradea) [5]. It must be noted though that the German natural scientist Phillippi who gave the first taxonomic description of the gastropod taxon *Melanopsis parreyssii* in his seminal volume from 1847 [6] (page 176 and Table 4, Figure 15) mentions Hungary as the type locality and the Austrian naturalist von Mühlfeld as the collector. Unfortunately, not a single word is given about the exact locality or the time and area of von Mühlfeld's visit. No further details on how the

Although there is no exact way to prove that the referred specimen was collected from Püspökfürdő (Baia Mai 1, Romania today), this assumption cannot be fully refuted either, as modern occurrences of this taxon are strictly restricted to a single locality, the referred thermal lake, with no others known. The first detailed geological description of the lacustrine deposits and the embedded Melanopsis taxa comes from the Austrian geologist von Heinrich

His profile, located at the lakeshore, starts with an embryonic humus layer [7]. The lack of a map displaying the exact location, orientation of his work, as well as the environmental changes of the past centuries hampered the later comparative use of his first description. Yet his work is by no means futile as the major geological units identified and described by him were clearly traceable in later works on the lacustrine deposits as well. So, the referred gastropod taxa appear in later publications from the late nineteenth century as well [8]. Despite the promising start, the first detailed presentation on the Quaternary mollusk fauna of Püspökfürdő, including morphological changes observed on the shells of Melanopsidae, was given only in 1890 by the Hungarian amateur naturalist Mihály Tóth on the 25th Congress of Hungarian Medical Doctors and Naturalists held in Nagyvárad (Oradea) [9]. He presented a series of mollusk shells collected via singling from a 2-m-deep profile. In addition, based on the observed variations, he lined up an evolutionary series with numerous members. In his view, the lake harboring the *Melanopsis* taxa is older than the so-called Old Alluvial (presently known as the Holocene epoch). Thus, these gastropods must derive from a Tertiary ancestor, whose descendants managed to survive the cold periods of the Diluvial (Pleistocene epoch). His work is the first presentation of the referred ice age refugia hypothesis in Central Europe. Considering the formerly accepted relatively short time

specimen described were attained.

94 Biological Resources of Water

Wolf [7].

**Figure 1.** Location of the sites mentioned in this study on the Holdridge-type bioclimatological map of Szelepcsényi et al. [69]: (1) Lake St. Ladislaus, Püspökfürdő-Nagyvárad (Baia Mai 1, Oradea, Romania); (2) Petény rock shelter (Bükk Mts, Hungary); (3) Rejtek rock shelter (Bükk Mts, Hungary); (4) protected marshland, Bátorliget (Nyírség, Hungary); (5) Selyemrét, Ócsa (Danube-Tisza interfluve, Hungary); and (6) brickyard (Crvenka, Serbia).

span of the Pleistocene at ca. 600 Ky [10–11] compared to the modern known value of 2.58 My [12–16], his postulation is rather remarkable considering our modern understanding of speciation and macroevolution.

one by Tóth after careful consideration of the geology and geomorphology of the area and the available publications [8–9]. Kormos gave a detailed description of the stratigraphy and geology in addition to the identified *Theodoxus* and *Melanopsis* taxa including the ones described by Brusina [18–21]. What is more a geological compilation of regionally available boreholes is also given along with maps displaying the exact location of these including his own and Tóth's profile as well. Thus, Kormos' seminal work could have been considered as a reliable foundation for our future research. The most important bullet

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• Taxa of the genera *Melanopsis* and *Theodoxus* (*Neritina)* identified in the lacustrine deposits must have a Tertiary common ancestor. In his view, this ancestor must be found in the Late

• Some taxa of the genus *Melanopsis* from Lake St. Ladislaus have clear evolutionary relationship with certain taxa of the genus *Fagotia* (considered as *Melanopsis* by him), especially the ones of *Fagotia acicularis* and *Fagotia esperi* [20]. These latter two taxa now known as *Esperiana* (*Microcolpia*) *daudebartii acicularis* (Férussac, 1823) and *Esperiana* (*Fagotia*) *esperi* (Férussac, 1823) are considered to be Pontian from a biogeographical point of view by certain researchers [24]. However, cyclical recurrence of these taxa in the malacofauna of the Carpathian Basin is connected to the warmer periods of the Pleistocene, that is, inter-

It must be emphasized though that the presence of a special waterlily *Nymphaea lotus thermalis* in Lake St. Ladislaus leads numerous botanists to the conclusion that the area is a true subtropical relict of a former geological period [22, 23, 27, 28] despite a clear objection of other botanists, who were highly skeptic regarding the origin and age of immigration of the referred plant taxon [29, 30]. So Kormos simply adopted the generally accepted scientific notion of his era along with another famous malacologist studying the modern mollusk fauna

WWI brought a sudden halt to malacological investigations. The only exception is perhaps an article published by Pauca [33] following the 1933 conservation of the site. Pauca kept only two taxa *Melanopsis parreissi* and *Melanopsis sikorai* from the ones listed by the former researchers providing highly questionable justification for his choice. In addition, no reason was given why these two were considered to be relict taxa from the Late Tertiary. His views were systematically adopted in later studies on the Romanian mollusk fauna [34] as well as the malacofauna of the region [24, 35] despite Diaconesa and Popa's works from the 1960s [36, 37], who clearly justified a Holocene timing of waterlily the invasion into the thermal lake. The origin and evolution of the Melanopsidae of Lake St. Ladislaus are far from settled and are a constant subject of scientific debates [38–42]. Yet, as it is an important hallmark in the question of Carpathian Basin refugia, a brief discussion based on our latest findings is

WWI meant an end not only to malacological research done on the unique Melanopsidae of Lake St. Ladislaus but on the question of refugia in Hungary and Central Europe as well. Not

Tertiary mollusk fauna of the southern parts of the Carpathian Basin.

glacials, and by no means to the Neogene Period (Tertiary) [25, 26].

points of his work are:

of the region: Lajos Soós [31, 32].

presented in the next chapter.

**Figure 2.** View of thermal Lake St. Ladislaus near Nagyvárad-Püspökfürdő (Oradea, Bai 1 Mai, Romania) in 1999 preceding its complete desiccation.

Tóth's work gave a major impetus to further detailed malacological studies on the mollusk fauna of the lake in the forthcoming decades involving the two internationally known malacologists of the Austro-Hungarian Monarchy: the Croatian Spiridon Brusina and the Hungarian Tivadar Kormos as well [17–21]. Their work included the genera *Melanopsis* and *Theodoxus* as well. Brusina examined the shells collected by Tóth, in addition to the ones collected by himself from the surficial deposits alone [17]. No profiles or boreholes were deepened to yield him stratigraphically reliable data and samples, which had serious consequences leading to erroneous observations and statements in the future. In his work Brusina identified eight different taxa of the *Melanopsis* genus, including the first described *Melanopsis parreyssii*. In addition, 23 varieties were mentioned. Unfortunately, his work is lacking a detailed taxonomic description and figures, having only a short diagnosis of each taxa in two or three sentences [17]. Brusina, based on his readings of the works of a paleobotanist Móric Straub [22, 23] describing a special waterlily from the thermal lake, considered the mollusks as representatives of a remnant Subtropical Tertiary oasis*.* Tivadar Kormos on the other hand prepared a new 11-m-deep composite profile near the one by Tóth after careful consideration of the geology and geomorphology of the area and the available publications [8–9]. Kormos gave a detailed description of the stratigraphy and geology in addition to the identified *Theodoxus* and *Melanopsis* taxa including the ones described by Brusina [18–21]. What is more a geological compilation of regionally available boreholes is also given along with maps displaying the exact location of these including his own and Tóth's profile as well. Thus, Kormos' seminal work could have been considered as a reliable foundation for our future research. The most important bullet points of his work are:


It must be emphasized though that the presence of a special waterlily *Nymphaea lotus thermalis* in Lake St. Ladislaus leads numerous botanists to the conclusion that the area is a true subtropical relict of a former geological period [22, 23, 27, 28] despite a clear objection of other botanists, who were highly skeptic regarding the origin and age of immigration of the referred plant taxon [29, 30]. So Kormos simply adopted the generally accepted scientific notion of his era along with another famous malacologist studying the modern mollusk fauna of the region: Lajos Soós [31, 32].

Tóth's work gave a major impetus to further detailed malacological studies on the mollusk fauna of the lake in the forthcoming decades involving the two internationally known malacologists of the Austro-Hungarian Monarchy: the Croatian Spiridon Brusina and the Hungarian Tivadar Kormos as well [17–21]. Their work included the genera *Melanopsis* and *Theodoxus* as well. Brusina examined the shells collected by Tóth, in addition to the ones collected by himself from the surficial deposits alone [17]. No profiles or boreholes were deepened to yield him stratigraphically reliable data and samples, which had serious consequences leading to erroneous observations and statements in the future. In his work Brusina identified eight different taxa of the *Melanopsis* genus, including the first described *Melanopsis parreyssii*. In addition, 23 varieties were mentioned. Unfortunately, his work is lacking a detailed taxonomic description and figures, having only a short diagnosis of each taxa in two or three sentences [17]. Brusina, based on his readings of the works of a paleobotanist Móric Straub [22, 23] describing a special waterlily from the thermal lake, considered the mollusks as representatives of a remnant Subtropical Tertiary oasis*.* Tivadar Kormos on the other hand prepared a new 11-m-deep composite profile near the

**Figure 2.** View of thermal Lake St. Ladislaus near Nagyvárad-Püspökfürdő (Oradea, Bai 1 Mai, Romania) in 1999

preceding its complete desiccation.

96 Biological Resources of Water

WWI brought a sudden halt to malacological investigations. The only exception is perhaps an article published by Pauca [33] following the 1933 conservation of the site. Pauca kept only two taxa *Melanopsis parreissi* and *Melanopsis sikorai* from the ones listed by the former researchers providing highly questionable justification for his choice. In addition, no reason was given why these two were considered to be relict taxa from the Late Tertiary. His views were systematically adopted in later studies on the Romanian mollusk fauna [34] as well as the malacofauna of the region [24, 35] despite Diaconesa and Popa's works from the 1960s [36, 37], who clearly justified a Holocene timing of waterlily the invasion into the thermal lake. The origin and evolution of the Melanopsidae of Lake St. Ladislaus are far from settled and are a constant subject of scientific debates [38–42]. Yet, as it is an important hallmark in the question of Carpathian Basin refugia, a brief discussion based on our latest findings is presented in the next chapter.

WWI meant an end not only to malacological research done on the unique Melanopsidae of Lake St. Ladislaus but on the question of refugia in Hungary and Central Europe as well. Not long after, however, studies implemented on the woodland mollusk fauna of a species-rich marshland near Bátorliget, NE Hungary initiated another debate regarding a potential refugia for temperate mollusk taxa in the basin during the ice age [43, 44]. Evidence for the survival of temperate woodlands in the Carpathian Basin during the Pleistocene was first presented between 1956 and 1969 by the paleobotanist József Stieber based on his detailed anthraconomical studies of wood remains deriving from cave sites in the Bükk Mts and loess/paleosol profiles from different parts of Hungary [45–48]. Thirty years after Stieber's seminal work, members of a British-Hungarian research group managed to independently corroborate the idea of Stieber on the presence of temperate woodland refugia in the Carpathian Basin [49– 56]. Besides the presence of woodland refugia, ice age refugia for several temperate grassland elements have also been recently identified [57–61]. Detailed malacological studies starting from the 1980s and the accompanying reconstruction of Late Glacial and Holocene vegetation changes have brought the question of ice age refugia into focus again [54, 55, 62–65]. Complementing comprehensive paleoecological investigations of loess/paleosol sequences from various parts of the basin using numerous biotic proxies (mollusks, phytoliths, alkanes) clearly highlighted the presence of temperate grassland refugia in the southern parts of the Great Hungarian Plain and its wider surroundings [53, 54, 66–70]. In the following chapters, a short overview of the results of these works is also presented in addition to those of freshwater and woodland mollusk refugia.

gastropod taxon *Melanopsis*. However, for our final evaluation, the material of the longer profile was used. Here a larger volume of samples (ca. 30 l) yielded several thousand shells yielding better representativity of the original mollusk fauna. The forms and varieties described by Tóth [9], Brusina [17], and Kormos [18–21] were all present in the studied samples from both profiles [38, 39]. The identified taxa were further investigated using X-ray photographs of the shells (**Figure 3**) as this way even minor morphological and size differences could have been

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After a meticulous study of shell variations from different parts of the profile, a clear evolutionary lineage could have been outlined. In the layers corresponding to the LGM as well as the Heinrich 1 event [71–73], smooth shelled forms prevailed, displaying a close affinity to the taxon *Fagotia acicularis* [*Esperiana* (*Microcolpia*) *daudebartii acicularis*]. Other morphological varieties or taxa were clearly missing from these horizons. This horizon and its dominant taxon were missed in the works of Neubauer and his colleagues [41, 42], because their analysis was restricted to museum specimens representing those of the surficial collections made by Brusina [17] and the 2-m-deep profile of Tóth [9]. So the projection of their findings to our 8.4-m-deep profile [38, 39] is highly misleading, similarly to their delineation of the Pleistocene–Holocene boundary [41]. According to the recorded 14C age of a charcoal piece from the depths of 596–600 cm in our profile (10,789–11,185 cal BP years), the majority of the profile can be dated to the Holocene. The Pleistocene/Holocene boundary could have

**Figure 3.** X-ray photographs of shells of various *Esperiana* (Microcolpia) taxa identified from Lake St. Ladislaus, Nagyvárad-Püspökfürdő (Oradea, Baia 1 Mai, Romania): (1) *Esperiana* (*Microcolpia*) *daudebartii acicularis* [*Fagotia acicularis*] (Férussac, 1823), (2) *Microcolpia parreyssii sikorai* (Brusina, 1903), (3) *Esperiana daudebartii daudebartii* (Prevost,

1821) [*Esperiana daudebartii acicularis F. thermalis*], and (4) *Microcolpia parreyssii parreyssii* (Philippi [6]).

noted as well.
