Coordinated response of endemic gastropods to Late Glacial and Holocene climate-driven paleohydrological changes in a small thermal pond of Central Europe

Abstract

The thermal spring-fed Lake Pețea located in NW Romania southeast of the city of Oradea harbors a unique endemic warm water biota. It is the only location in Europe where thermal water endemic melanopsid Microcolpia parreyssii (Philippi, 1847) lived along with the highly endangered warm-water relict neritid Theodoxus prevostianus. Lake Petea’s evolution was mainly controlled by major climate-driven hydrological changes also seen in regional records. The hydrological changes were mainly controlled by varying input of thermal water due to recurring increased/decreased recharge of the underground karst water system. The driving factor was warming connected to the interstadial GI 1 increasing recharge by melting of regional ice sheets in the Late Glacial. Conversely, during the Younger Dryas (H0) and the Holocene increasing/decreasing moisture availability was in control. Low stands created multiple bottlenecks reducing genetic variability seen in the appearance of extreme morphologies during next rapid climate melioration. The studied gastropods responded mostly similarly to changes controlling the availability of elements in shell construction and habitat reduction leading to changes in shape, density, size. Periods of lower lake levels and reduced warm water input are characterized by the emergence of elongated tightly coiled shells while globular, compressed loosely coiled shells develop at times of warmer water provision and increased Mg availability. In size there is a contrasting trend. Namely globose Th. prevostianus shells are larger than the elongated ones. Conversely globose, compressed Microcolpia are generally smaller than their elongated spindle-shaped counterparts. In this sense the development of dwarf morphotypes in warmer water habitats is characteristic of Lake Pețea melanopsids. This type of dwarfism i.e. the reduction of shell size is lacking though in Lake Pețea neritids. Our findings also confirm the presence of various ecophenotypes of Microcolpia in the pond degrading our endemic species Mi. parreyssii to a variety of Mi. daudebartii.

Assessing phenotypic variation and plasticity of endemic gastropods from thermal water refugia using complex morphometric techniques: A case study of Lake Pețea melanopsids

“…parreyssii parreyssii (Philippi, 1847) has a preference for relatively higher water temperatures above 26°C, water temperature shifts might have contributed to the emergence of these morphotypes as well as mentioned by Sümegi, Molnár, Sávai, and Gulyás (2012;Sümegi, Molnár, Sávai, & Töviskes, 2012;Sümegi et al, 2018). This view is further supported by an observable increase in abundance of the thermophilous Theodoxus prevostianus (C. Pfeiffer 1828) in parallel with the appearance of shouldered melanopsids in both the lowermost and upper part of our sequence (Figures 9 and 10) (Gulyás & Sümegi, 2023, 2024. Based on the presence of this taxon, water temperatures reaching and or exceeding 23°C can be assumed (Sîrbu & Benedek, 2005, 2009Sümegi, Molnár, Sávai, & Gulyás, 2012).…”

“…The next unit is a 1 m organic-rich lacustrine sediment with thin silty, sandy marl intercalations overlain by 1 m of clay-rich silty marls again deposited in a eutrophic thermal lake system corresponding to the final ca. 5 kys (Gulyás & Sümegi, 2023, 2024. It is worth noting how well the stratigraphy corresponds in both the position and thickness of the individual layers to that of the 1903 profile of Kormos (1905b) (Figure 1).…”

“…The random appearance of morphologies like the ones noted for the Neogene melanopsids of Kos Island, Greece, may indicate convergent evolution. As seen from our stratigraphic record, the presence of multiple bottleneck events controlling the formation of morphotypes of two identified taxa of Lake Pețea Microcolpia must be assumed (Gulyás & Sümegi, 2024). To clarify the nature of these (water temperature shifts, habitat segmentation via emergence of hot/cold water spots in generally cooler/warmer waters, paludification, habitat segmentation due to lowstands), the introduction of further data derived from the analysis and interpretation of abiotic and biotic proxies complemented by information on temporal changes of morphological disparity is needed (Gulyás & Sümegi, 2024).…”

“…The entire obtained material derives from stratified samples of the geological profile of the 2012 campaign created in the center of the pond (Gulyás & Sümegi, 2023, 2024Sümegi, Molnár, Sávai, & Gulyás, 2012;Sümegi, Molnár, Sávai, & Töviskes, 2012;Sümegi et al, 2018) (Figure 1). The base of the 8.4 m sequence is given by limestone pebbles overlain by ca.…”

“…The phenotypic plasticity of extant and fossil melanopsids has been widely documented in various lacustrine and fluvial habitats (Bandel, 2000;Bändel et al, 2007;Elkarmi, 2006;Geary, 1990Geary, , 1992Geary et al, 1989Geary et al, , 2002Geary et al, , 2012Glaubrecht, 1993;Heller et al, 2005;Heller & Sivan, 2001, 2002Michel, 1994;Neubauer et al, 2013, Neubauer, Harzhauser, et al, 2016Papp, 1955). Nevertheless, highresolution, well-dated fossil records from the mentioned thermal springs and spring-fed ponds are scarce (Gulyás & Sümegi, 2023, 2024Neubauer et al, 2014;Sümegi et al, 2018). Lake Pețea is located in NW Romania, southeast of the city of Oradea (Figure 1).…”