Aspects of paleoclimatic and paleoceanographic evolution of the north Aegean Sea through the Holocene are revealed by the study of quantitative variations in planktonic foraminiferal, pteropodal, and palynomorph assemblages; the isotopic composition of planktonic foraminifera; and hydrographic-related indices, extracted from two high-sedimentation rate cores from the North Aegean Trough. Focusing on the last ~10 cal ka BP, the current Holocene subdivision (Greenlandian, Northgrippian, and Meghalayan) confirms the traditional understanding of an evolution from wetter (Greenlandian) to gradually drier (Northgrippian and Meghalayan) climatic conditions and further highlights the role of changing seasonality during this time. The most warm and humid phase corresponds to the time of the sapropel S1 deposition (9.6–6.1 cal ka BP). The Holocene climatic instability of the study area is further supported by six episodes of brief cooling (North Aegean cooling; NAEGC6–NAEGC1) centered at 9.30, 8.05, 7.05, 4.55, 3.55, and 2.05 cal ka BP, reflected by significant faunal changes and oxygen isotope enrichments. These cold/arid events are coeval with equivalent cooling events that have been described in different basins of the Mediterranean Sea, while signal similarities with equivalent changes in the intensity of the Siberian high suggest a climatic link between the studied area and the high-latitude areas.

A multidisciplinary study was conducted in order to investigate the environmental factors affecting the planktonic foraminiferal and pteropod communities of the south Aegean Sea. Aspects of the Late Quaternary paleoceanographic evolution were revealed by means of quantitative analyses of planktonic foraminiferal and pteropod assemblages (including multivariate statistical approach; principal component analysis (PCA)), the oxygen (δ¹⁸O) and carbon (δ¹³C) isotopic composition of planktonic foraminifera and related paleoceanographic (planktonic paleoclimatic curve (PPC), productivity (E-index), stratification (S-index), seasonality) indices, extracted by the gravity core KIM-2A derived from the submarine area between Kimolos and Sifnos islands. Focusing on the last ~21 calibrated thousands of years before present (ka BP), cold and eutrophicated conditions were identified during the Late Glacial period (21.1–15.7 ka BP) and were followed by warmer and wetter conditions during the deglaciation phase. The beginning of the Holocene was marked by a climatic amelioration and increased seasonality. The more pronounced environmental changes were identified during the deposition of the sapropel sublayers S1a (9.4–7.7 ka BP) and S1b (6.9–6.4 ka BP), with extremely warm and stratified conditions. Pteropod fauna during the sapropel deposition were recorded for the first time in the south Aegean Sea, suggesting arid conditions towards the end of S1a. Besides sea surface temperature (SST), which shows the highest explanatory power for the distribution of the analyzed fauna, water column stratification, primary productivity, and seasonality also control their communities during the Late Quaternary.

Well-preserved leaves and rhizomes of the Mediterranean endemic marine angiosperm Posidonia oceanica and the rich associated mollusc and fish fauna are contained in the early Pleistocene shallow siliciclastic sediments of the Kritika Formation of the island of Rhodes (Greece). The leaf moulds are preserved in fine-grained sands, whereas the rhizomes are found in situ within coarse-grained sediments. The associated molluscan fauna includes 79 species, 47 gastropods and 32 bivalves, most of them extant. The rhizome-associated community comprises 49 species and the leaves-associated community includes 30 species. Small gastropods grazing on microalgae (Rissoidae, Cerithiidae, Trochidae) are the most abundant elements of the fauna, however carnivorous gastropods (Nassariidae, Naticidae, Muricidae) are also diverse. Among the bivalves Lucinidae (e.g., Lucinella) numerically dominate the deeper infauna and other chemosymbiont bivalves, as Ungulinidae (Diplodonta) are also common. Although many species are not associated exclusively with this seagrass and they may occur in other environments as well, they generally thrive on P. oceanica leaves and rhizomes. The Posidonia oceanica meadows were also inhabited by several characteristic fish species which thrive in the seagrass meadows of the eastern Mediterranean until today. The studied fauna is the first reported from the early Pleistocene of Greece and shows similarities to the modern counterparts of Posidonia oceanica meadows, providing new data on the resilience of seagrass ecosystems to environmental change in general.