Quantitative analyses of coccolithophores, planktonic foraminifers, dinoflagellate cysts and pollen assemblages were carried out on shallow (NS-14) and deeper (NS-40) sediment cores from the south-eastern Aegean Sea. Nine coccolithophore (ACE 1–9) and nine planktonic foraminifer (APFE 1–9) ecozones, correlated with dinoflagellate cyst evidence, have been defined for the last ~14.5 cal. ka. Additionally, eight pollen assemblage zones (PAZ 1–8) have been recognised and correlated with the plankton ecozones. Although generally consistent with existing schemes for the central and eastern Mediterranean, the established high resolution ecostratigraphy has led to an expanded palaeoecological reconstruction of the Late Glacial–Holocene archive in the south-eastern Aegean Sea, defining two warm and humid phases at 9.3–8.6 and 7.6–6.4 cal. ka B.P., associated with the deposition of the early Holocene sapropel S1, and a third one between 5.2 and 4.2 cal. ka B.P. The high sedimentation rates which characterise the study area enabled the detection of even minor and brief climatic events in the Aegean Sea during S1 deposition times.
New micropaleontological, palynological, and geochemical results from a relatively shallow (∼500 m) sediment core (NS-14) in the south-eastern Aegean Sea provide a detailed picture of the regional expression of sapropel S1 formation in this sub-basin of the eastern Mediterranean Sea. Specifically, freshwater input during ∼10.6–10.0 ka BP has preceded the deposition of S1. Further decrease in surface water salinity is evidenced between 10.0 and 8.5 ka BP at the lower part of S1a, which in respect to S1b, is featured by warmer (∼19.5 °C) and more productive surface waters associated with dysoxic bottom conditions. A series of coolings detected within the S1 depositional interval, may be linked to outbursts of cold northerly air masses and relevant pulses in the deep-intermediate water ventilation that caused the S1 interruption between 7.9 and 7.3 ka BP and culminated during the deposition of S1b, with the decline of deep chlorophyll maximum (DCM) at ∼6.5 ka BP. The climate instability and the relevant absence of anoxia weakened the organic matter preservation in the shallow south-eastern Aegean margin during the S1 times. NS-14 record provides evidence for a distinct mid Holocene warm (up to ∼25 °C) and wet phase associated with the deposition of the sapropel-like layer SMH (Sapropel Mid Holocene), between 5.4 and 4.3 ka BP. The SMH layer could represent evidence of on-going, albeit weak, African monsoon forcing, only expressed at the south-eastern edge of the Aegean Sea. Its end is associated with the 4.2 ka BP Northern Hemisphere megadrought event and the termination of the African Humid Period at 3.8 ka BP.
During the last decades, hundreds of species of Indo-Pacific origin from the Red Sea have traversed the Suez Canal and settled in the Eastern Mediterranean. Nowadays, Amphistegina lobifera Larsen, the most common epiphytic, symbiont- bearing large foraminifer, is known to be a successful immigrant that is widely distributed in the coastal ecosystems of the Eastern Mediterranean Sea. In this study, we provide additional sites of occurrences on distributional range and settlement of A. lobifera in the Greek coastal ecosystems. The high relative abundances recorded are the result of very successful inhabitation of thisspecies in the Aegean ecosystems and suggest that it has become significant part of the epiphytic foraminiferal fauna.
An apparently unambiguous combination coccosphere from the Eastern Mediterranean (Aegean Sea, Greece) is documented involving Syracosphaera protrudens Okada & McIntyre, 1977 and Syracosphaera pulchra Lohmann, 1902 HOL pirus-type. This finding is difficult to interpret in terms of the current understanding of Syracosphaera taxonomy and adds evidence to the hypothesis of a distinctly complex Syracosphaera pulchra life cycle.
A combined study of extant nannoflora (calcareous nannoplankton/coccolithophores) and microfauna (ostracods, benthic foraminifera) was conducted in summer period between 2001 and 2003 at Kastro and Korthi gulfs, Andros Island (central Aegean Sea). The results of our study showed that the studied three groups can provide evidence of stress on the natural assemblages and therefore can be used as proxies of declining coastal environments. In particular, the existence of coccolithophore communities with low species diversities, high dominance values and the predominance of Emiliania huxleyi with malformed coccoliths indicate unstable environmental conditions. The environmental stress in ostracod assemblages is mainly proved by the decreasing abundances of Xestoleberis spp. specimens. The response of benthic foraminifers was demonstrated by the increase of foraminiferal tests with morphological abnormalities and the replacement of Amphistegina lobifera – an environmental health proxy- by miliolids and small rotalliid forms.
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