**2. Ice age refugia in hot-water springs and lakes: Lake saint Ladislaus, Nagyvárad-Püspökfürdő (Lake Petea, Oradea region)**

In 1999, following the works of Kormos [18–21] and Tóth [9], a new 2-m-deep geological profile was created in the littoral part of Lake St. Ladislaus adjacently to the one of Tóth by members of our Geoarcheological and Quaternary Paleoecological research group. In addition, numerous undisturbed cores were also taken to delineate the spatial distribution of the identified stratigraphic horizons. Another 8.4-m-deep profile was dug next to that of Kormos in 2012 as part of a bilateral Romanian-Hungarian project, this time in the fully dried-up lakebed. The first geological profile spans the interval from the Late Glacial, while the 2012 one dates back to the last glacial maximum (LGM) of the last glacial.

Lithological observations made on the shorter profile are fully congruent with the one made by Tóth [9]. The profile starts with coarse silt-rich clayey lacustrine silts followed by lacustrine carbonate muds ending in highly altered peats representing the final desiccation of the lakebed. The stratigraphy of the longer, more recently established profile is much more complex recording several sedimentary changes. Nevertheless, the ice age part here is likewise represented by clayey, fine-silty coarse silts similarly to the bottom part of the shorter profile. A significant increase in the carbonate content is recorded only from the Late Glacial part of the profile, which also means that the more complex lithology is restricted to the upper Holocene parts. Samples from both profiles are fossiliferous yielding representatives of the 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 noted as well.

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 freshwa-

ter and woodland mollusk refugia.

98 Biological Resources of Water

**2. Ice age refugia in hot-water springs and lakes: Lake saint Ladislaus, Nagyvárad-Püspökfürdő (Lake Petea, Oradea region)**

one dates back to the last glacial maximum (LGM) of the last glacial.

In 1999, following the works of Kormos [18–21] and Tóth [9], a new 2-m-deep geological profile was created in the littoral part of Lake St. Ladislaus adjacently to the one of Tóth by members of our Geoarcheological and Quaternary Paleoecological research group. In addition, numerous undisturbed cores were also taken to delineate the spatial distribution of the identified stratigraphic horizons. Another 8.4-m-deep profile was dug next to that of Kormos in 2012 as part of a bilateral Romanian-Hungarian project, this time in the fully dried-up lakebed. The first geological profile spans the interval from the Late Glacial, while the 2012

Lithological observations made on the shorter profile are fully congruent with the one made by Tóth [9]. The profile starts with coarse silt-rich clayey lacustrine silts followed by lacustrine carbonate muds ending in highly altered peats representing the final desiccation of the lakebed. The stratigraphy of the longer, more recently established profile is much more complex recording several sedimentary changes. Nevertheless, the ice age part here is likewise represented by clayey, fine-silty coarse silts similarly to the bottom part of the shorter profile. A significant increase in the carbonate content is recorded only from the Late Glacial part of the profile, which also means that the more complex lithology is restricted to the upper Holocene parts. Samples from both profiles are fossiliferous yielding representatives of the 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]).

been placed between 600 and 620 cm in our 8.4-m-deep profile. So, during the LGM, forms of the *Melanopsis* taxa displaying a close affinity to *Fagotia acicularis* [*Esperiana (Microcolpia) daudebartii acicularis*] were present. A longer type of this taxon with a thicker shell turns up in the Late Glacial part of the profile termed as *Fagotia acicularis F. thermalis* besides another smaller type which was described as *Melanopsis hazayi* by Brusina [17]. In addition, several other forms, taken to represent individual taxa by researchers during the late nineteenth and early twentieth centuries, turn up here as well (*sublanceolata, szontaghi*, *mucronifera*, *tothi*, *hazayi*, *staubi, franciscae*, *vidovici*, and *hazayi*) [9, 17, 18–21]. The appearance of these various new forms is clearly connected to a major environmental change noticed in a sudden increase in the carbonate content and water-soluble Ca and Mg content of the samples. This marked change in the geochemistry and the lithological character was so strong that it must signal a significant increase in the water temperature of the hot spring and the lake during the Late Glacial following the H1 event compared to temperatures characteristic for the LGM. It is also the horizon, where the first smooth, keeled, and shouldered shell forms of *Melanopsis* are recorded, though subordinately. These smooth, keeled, and shouldered shells having spiral striae running parallel with the suture are similar to the ones of the taxon *Melanopsis sikorai* (Brusina [17]). On the basis of these observations, we can postulate that the ecophenotypes leading to the evolution of the endemic taxon *M. parreyssi* inhabiting the modern lake must have emerged even during the Late Glacial. The opening of the Holocene marked the appearance of further sculpted, shouldered forms (*M. sublanceolata*, *M. staubi*), but the Late Glacial ecophenotypes were also preserved. The Early and Middle Holocene are characterized by an outstanding variety of shell forms. The Holocene also marks the disappearance of the smooth forms displaying close affinity to *Fagotia acicularis* [*Esperiana* (*Microcolpia*) *daudebartii acicularis*] including the taxa determined as *M. hazayi* and *Fagotia acicularis F. thermalis*. The Late Holocene corresponding to the last 2000 years is characterized by an increase in the organic content of the lacustrine deposits marking the transition to a marshland at the end of the Iron Age. By this time the presence of ribbed and shouldered forms can be attested representing the so-called *Melanopsis hungarica* assemblage (*M. hungarica*, *M. themaki*). It is also the time when the first representatives of the modern endemic taxon *Microcolpia* (*Melanopsis*) *parreyssii parreyssii* (Phillipi [6]) turn up. This endemic taxon represents the final member of an evolutionary lineage starting from the Late Pleistocene ancestor *Esperiana* (*Microcolpia*) *daudebartii acicularis* through various Late Glacial and Holocene ecophenotypes. Findings of detailed genetic analysis have independently corroborated our assumptions regarding the evolution of this taxon [74].

thermal lakes in the preservation of mollusks even during the coldest periods of the ice age in the area of the Carpathian Basin. As several such systems are known from various parts of the basin as well as the transitional zone to the Carpathian Mts, one can presume that these also could have a significant role in the survival of warmth-loving mollusk taxa during the

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

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

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**3. Ice age woodland refugia in highlands between the elevations of 500–700 m ASL: Petény cave and Rejtek 1 rock shelter, Bükk Mts, NE** 

Excavations starting in the 1950s as part of a collaborative work of vertebrate paleontologists, anthracologists, and archeologists in two cave systems found in the Bükk Mts in NE Hungary yielded outstanding records regarding the presence of ice age woodland refugia in a highland setting of the Carpathian Basin [45–48, 75–78]. One of the studied caves was formed in Triassic limestone at an elevation of 735 m ASL (Petény Cave) (**Figure 1**). The other, the Rejtek rock shelter, found at an elevation of 500 m ASL was formed in Jurassic limestone. Both cave systems are facing south. According to the retrieved vertebrate fauna and recovered archeology, sediment accumulation must have initiated from the terminal part of the last glacial in these karstic depressions. Fine-stratigraphic sampling of the identified lithological horizons yielded numerous charcoal pieces. The taxonomic composition of these charred plant remains indicated the emergence of mixed taiga woodland at this elevation during the last stage of the last glacial [45–48]. Besides the clear dominance of spruce and Scots pine, scattered patches of deciduous elements like elm, oak, lime, maple, beech, ash, as well as hazel were also present in these woodlands. On the basis of this information, József Stieber came up with the idea regarding the presence of ice age woodland refugia for temperate thermomesophylous trees in the Carpathian Basin for the first time [45–48]. Unfortunately, his observations were by no means welcomed by the majority of Hungarian botanists of his time. It was only in 1999 when a British-Hungarian research group managed to corroborate his presumption independently [49–52, 55, 56]. The samples taken by Stieber and his colleague Dénes Jánossy yielded numerous terrestrial mollusk shells, which were handed over for further evaluation to the late Endre Krolopp, an outstanding Quaternary malacologist of the late twentieth century. The malacological remains of both caves have been scientifically evaluated along with a revision of the charcoal remains complemented by 14C dating of the major stratigraphic units sampled in the 1950s [55, 56]. According to the results of these investigations, Central European woodland mollusk elements prevailed in this area from even the

The prevailing taxon of the Late Glacial horizon is *Cochlodina cerata*. The modern distribution of this taxon's habitat is found in the area of the Northern, Northeastern Carpathian Mts ranging from the lower alpine woodlands of the foothills to the upper alpine woodlands to a height of ca. 1000 m [79–84]. Consequently, the studied region in the Bükk Mts, NE Hungary, between the elevations of 500–750 m ASL must have acted as an ice age

cold spells of the ice age.

last glacial onward (**Figure 4**).

**Hungary**

The final part of the story is rather heartbreaking as this unique Middle Pleistocene refugee forming a cradle for various endemic gastropod taxa, including *Theodoxus prevostianus*, is bound to fully disappear in a couple of years. The last members of the endemic *Microcolpia* (*Melanopsis*) *parreyssii parreyssii* (Phillipi [6]) are living among artificial conditions in the aquarium of a Hungarian research institute thanks to the quick response of dedicated zoologists to the human-induced desiccation of the lakebed of Lake St. Ladislaus. Although there have been measures taken to restore the previous conditions, the newly created artificial thermal lake system may not fully be capable to fulfill its preservational role as refugia in the future. Yet our records have clearly pointed to the importance of hot-water spring-fed thermal lakes in the preservation of mollusks even during the coldest periods of the ice age in the area of the Carpathian Basin. As several such systems are known from various parts of the basin as well as the transitional zone to the Carpathian Mts, one can presume that these also could have a significant role in the survival of warmth-loving mollusk taxa during the cold spells of the ice age.

been placed between 600 and 620 cm in our 8.4-m-deep profile. So, during the LGM, forms of the *Melanopsis* taxa displaying a close affinity to *Fagotia acicularis* [*Esperiana (Microcolpia) daudebartii acicularis*] were present. A longer type of this taxon with a thicker shell turns up in the Late Glacial part of the profile termed as *Fagotia acicularis F. thermalis* besides another smaller type which was described as *Melanopsis hazayi* by Brusina [17]. In addition, several other forms, taken to represent individual taxa by researchers during the late nineteenth and early twentieth centuries, turn up here as well (*sublanceolata, szontaghi*, *mucronifera*, *tothi*, *hazayi*, *staubi, franciscae*, *vidovici*, and *hazayi*) [9, 17, 18–21]. The appearance of these various new forms is clearly connected to a major environmental change noticed in a sudden increase in the carbonate content and water-soluble Ca and Mg content of the samples. This marked change in the geochemistry and the lithological character was so strong that it must signal a significant increase in the water temperature of the hot spring and the lake during the Late Glacial following the H1 event compared to temperatures characteristic for the LGM. It is also the horizon, where the first smooth, keeled, and shouldered shell forms of *Melanopsis* are recorded, though subordinately. These smooth, keeled, and shouldered shells having spiral striae running parallel with the suture are similar to the ones of the taxon *Melanopsis sikorai* (Brusina [17]). On the basis of these observations, we can postulate that the ecophenotypes leading to the evolution of the endemic taxon *M. parreyssi* inhabiting the modern lake must have emerged even during the Late Glacial. The opening of the Holocene marked the appearance of further sculpted, shouldered forms (*M. sublanceolata*, *M. staubi*), but the Late Glacial ecophenotypes were also preserved. The Early and Middle Holocene are characterized by an outstanding variety of shell forms. The Holocene also marks the disappearance of the smooth forms displaying close affinity to *Fagotia acicularis* [*Esperiana* (*Microcolpia*) *daudebartii acicularis*] including the taxa determined as *M. hazayi* and *Fagotia acicularis F. thermalis*. The Late Holocene corresponding to the last 2000 years is characterized by an increase in the organic content of the lacustrine deposits marking the transition to a marshland at the end of the Iron Age. By this time the presence of ribbed and shouldered forms can be attested representing the so-called *Melanopsis hungarica* assemblage (*M. hungarica*, *M. themaki*). It is also the time when the first representatives of the modern endemic taxon *Microcolpia* (*Melanopsis*) *parreyssii parreyssii* (Phillipi [6]) turn up. This endemic taxon represents the final member of an evolutionary lineage starting from the Late Pleistocene ancestor *Esperiana* (*Microcolpia*) *daudebartii acicularis* through various Late Glacial and Holocene ecophenotypes. Findings of detailed genetic analysis have independently corroborated our assumptions regarding the evolution

The final part of the story is rather heartbreaking as this unique Middle Pleistocene refugee forming a cradle for various endemic gastropod taxa, including *Theodoxus prevostianus*, is bound to fully disappear in a couple of years. The last members of the endemic *Microcolpia* (*Melanopsis*) *parreyssii parreyssii* (Phillipi [6]) are living among artificial conditions in the aquarium of a Hungarian research institute thanks to the quick response of dedicated zoologists to the human-induced desiccation of the lakebed of Lake St. Ladislaus. Although there have been measures taken to restore the previous conditions, the newly created artificial thermal lake system may not fully be capable to fulfill its preservational role as refugia in the future. Yet our records have clearly pointed to the importance of hot-water spring-fed

of this taxon [74].

100 Biological Resources of Water
