Geographic changes in the Aegean Sea since the Last Glacial Maximum: Postulating biogeographic effects of sea-level rise on islands

Abstract

In order to assess how the last sea level rise affected the Aegean archipelago, we quantified the magnitude and rate of geographic change for the Aegean islands during the last sea-level-rise episode (21 kyr BP-present) with a spatially explicit geophysical model. An island-specific Area-Distance-Change (ADC) typology was constructed, with higher ADC values representing a higher degree of change. The highest fragmentation rates of the Aegean archipelago occurred in tandem with the largest rates of sea-level-rise occurring between 17 kyr and 7 kyr ago. Sea-level rise resulted in an area loss for the Aegean archipelago of approximately 70%. Spatiotemporal differences in sea-level changes across the Aegean Sea and irregular bathymetry produced a variety of island surface-area loss responses, with area losses ranging from 20% to N90% per island. In addition, sea-level rise led to increased island isolation, increasing distances of islands to continents to N200% for some islands. We discuss how rates of area contractions and distance increases may have affected biotas, their evolutionary history and genetics. Five testable hypotheses are proposed to guide future research. We hypothesize that islands with higher ADC-values will exhibit higher degrees of community hyper-saturation, more local extinctions, larger genetic bottlenecks, higher genetic diversity within species pools, more endemics and shared species on continental fragments and higher z-values of the power-law species-area relationship. The developed typology and the quantified geographic response to sea-level rise of continental islands, as in the Aegean Sea, present an ideal research framework to test biogeographic and evolutionary hypotheses assessing the role of rates of area and distance change affecting biota.

Geography, climate, ecology: What is more important in determining bee diversity in the Aegean Archipelago?

“…Smaller islands can be assumed to comprise habitats less uneven in plant species richness, demonstrating higher plant density and, thus, floral resources, and may positively influence species exchange among islands (Sfenthourakis & Panitsa, ). Undoubtedly, species exchange has been much influenced by the Aegean Archipelago's complex geological history (e.g., Messinian Salinity Crisis, Pleistocene changes) (Simaiakis et al., ). Indeed, for the Aegean islands, Pleistocene palaeogeography has been identified as a key factor for the present distribution patterns (Fattorini, ; Poulakakis et al., ) and Pleistocene distances as the drivers of its current biota (Hausdorf & Hennig, ).…”

A review of the Pleistocene dwarfed elephants from the Aegean islands, and their paleogeographic context

“…In addition to the impact of tectonic events on the palaeogeography of the Aegean realm, global sea-level fluctuations have impacted the extension of emerged areas. Lykousis (2009), Kapsimalis et al (2009) and Simaiakis et al (2017) showed that the Cyclades were separated from mainland Greece during the Middle Pleistocene. The Mega-Cyclades palaeo-island became fragmented into separate islands after the Last Glacial Maximum (LGM) due to the combined sea-level rise and subsidence.…”

“…Indeed, the southern Aegean realm has been subsiding at least since the end of the Miocene (Lykousis 2009, Philippon et al 2014, Simaiakis et al 2017, and references therein). The seismic reflection profiles showed that after the Messinian Salinity Crisis, in the Early Pliocene the sea occupied the Myrtoon Basins and Saronikos Gulf, east of Peloponnese and south of Attiki respectively.…”

“…This is also the time interval during which a new marine connection between the southern and northern Aegean basins settled (mid Aegean trench), thus separating the eastern and western parts of the Aegean domain. Despite a progressive marine transgression, most parts of the Cyclades remained as land and connected to Attiki up to the Middle Pleistocene (Lykousis 2009, Simaiakis et al 2017. It was also the case for the Dodecanese islands which remained connected to the southwestern coast of Anatolia up to the Middle Pleistocene (Perissoratis and Conispoliatis 2003).…”

“…Since the pioneering work of Creutzburg (1963), several palaeogeographic maps of the Aegean region for the successive periods of the Neogene and Quaternary were proposed Papanikolaou 1981, Dermitzakis 1990, Anastasakis and Dermitzakis 1990, Perissoratis and Conispoliatis 2003, Anastasakis et al 2006, Lykousis 2009, Poulakakis et al 2015, Simaiakis et al 2017. Lykousis (2009) used data from seismic reflection profiles, subsidence rates, land observations (terraces and faults) and sea-level fluctuations during the glacial and interglacial periods to calculate the subsidence rates for the second half of the Quaternary in different domains of the Aegean.…”