Jane M. Reed

The tempo of Holocene climatic change in the eastern Mediterranean region: new high-resolution crater-lake sediment data from central Turkey

This study presents results from a multi-proxy analysis of cores taken in a crater-lake sequence from Eski Acigöl in centr-al Turkey which cover the period from pre-c. 16000 cal. yr BP to the present. The sediments comprise an upper unit of enerally non-laminated, banded to massive silts and peats of mid- to late-Holocene age, overlying a laminated unit of late-Pleistocene to early/mid-Holocenie age. The laminae, comprising mainly aragonite. amorphous silica (diatom frustules) and organic matter were formed in a relatively deep, dilute. meromictic lake. Pollen data indicate an abrupt replacement of Arteyisia-chenopod steppe by grass-oak-terebinth parkland during the period of laminae deposition, marking the start of the Holocene. A gradual increase in tree pollen during the early Holocene came to an end c. 6500 cal. yr BP (U-series and adjusted 14C timescale), when mesic deciduots taxa declined at the same time as lake levels fell. Human impact on regional vegetation is inferred from a sharp decline in oak around 4500-4000 cal. yr BP. Diatom, isotopic and mineralogical data indicate that during the second half of the Holocene the lake became relatively shallow and oscillated between fresh and brackish/evaporated water conditions. The contrast between wetter early and drier late-Holocene climatic conditions is matched by other eastern and central Mediterranean proxy climate data. While the Eski Acigöl sequence resembles Holocene hydroclimatic changes in the Saharo-Arabian zone and was also apparenitly linlked to orbital forcing, it is unlikely to have had the samlle direct cause, i.e., an expansion and subsequent retreat of monsoon rainfall.

A multi-proxy record of Holocene climatic change in southwestern Spain: the Laguna de Medina, Cádiz

Palaeolimnological data (diatoms, ostracods, foraminifera, molluscs, aquatic pollen and lithology) from a radiocarbon dated sediment core from a saline lake, the Laguna de Medina, provide the first complete record of Holocene lake-level change for southwest Spain for the last c. 9000 cal. years. The lake has always been relatively shallow but has exhibited marked fluctuations in salinity and water depth, especially in the earlier record when oscillations culminate in maximum lake levels from c. 6960-6680 cal. BP (c. 6070-5830 BP), indicating enhanced early to mid-Holocene humidity and a mid-Holocene humidity maximum. Prolonged shallowing thereafter reflects in part increased aridity in the later Holocene. Lake desiccation followed by a c. 800-yr phase (zone 2) of major limnological change commencing at c. 8000 cal. BP (c. 7200 BP), and a number of other abrupt desiccation events, are also noteworthy. The mid-Holocene maximum is consistent with widespread evidence for high lake levels around 6000 BP, but the underlying climatic mechanisms are uncertain; there is some evidence it may apply predominantly to the westerly (Atlantic) Peninsula, withi earlier maxima in the east. Phases of abrupt limnological change show affinities with African data; as in African lakes, the ′zone 2′ phase appears to be a response to global change centred on c. 8.1-8.2 cal. BP. Other correlations made are tenuous, due partly to the lack of preservation in the upper record of some of the proxies used. Other desiccation events currently appear to be of more local significance, reflecting high decadal- to century-scale climatic variability throughout the Holocene.

Pattern and Process in Balkan Biodiversity — An Overview

The morose manner in which the grand vizier, Jusuf Ibrahim, is reported by the celebrated writer, the Bosnian Serb, No Andric, to have recalled his Bosnian homeland probably reflects equally the opinions of the two men. In the 19th century, Ibrahim had been transferred from Bosnia in his early childhood to Istanbul, the most splendid city of its time, as part of a `harac’, or tax in blood, which was paid in the form of children by Christian families for them to be converted to Islam and trained as yanitsarees. Jusuf Ibrahim, the poor Bosnian child, went on to attain the highest position in the Ottoman’s court. Both men made successful careers in the outside world, but both apparently harboured deep-seated resentment about their early childhoods in Bosnia.

The recent palaeoecology and conservation status of Balkan Lake Dojran

Abstract Lake Dojran is a Balkan lake which is host to a number of endemic species and is of high conservation concern. We report the results of research into the present ecological status of the lake and its comparison with palaeolimnological data for recent human impact, based on modern zoobenthology, diatom and ostracod palaeoecology, sedimentology and 18 O/ 16 O and 13 C/ 12 C stable isotope ratios from shells of Darwinula stevensoni (Ostracoda) and Anodonta cygnea glochidia larvae (Mollusca). The results of the modern survey indicate that benthic faunal composition has changed substantially in recent years. However, in spite of documented eutrophication and major, human-induced fluctuations in lake level since the 1950s, the results of palaeoecological analyses indicate that Lake Dojran is still buffered from major ecological impact. The palaeolimnological datasets suggest, however, that an ecological threshold may have been reached, and remedial measures should now be considered. Ecological problems include not only a major decrease in water depth through water abstraction and the diversion of source waters for agricultural purposes, but also recent climatic aridity and anthropogenic pollution. However, geopolitical problems presently conspire against the formulation of a management strategy for the preservation of the lake and its endemic fauna and flora.

The Physical Geography of The Balkans and Nomenclature of Place Names

The complexity of Balkan physical geography, together with its location in an important transition zone of faunal and floral influences, will have influenced greatly the evolution of Balkan biodiversity. This chapter gives a broad description of the geology, topography and climate of the Balkan Peninsula which serves as a reference point for subsequent specialist chapters on the biodiversity of the Balkan flora and fauna. Since some of the geographic boundaries of the Balkans are not well demarcated the chapter begins with a discussion of how the territory is defined. For the international audience, it includes a brief summary of the nomenclature used for geographic features whose names vary locally.

The last glacial-interglacial cycle in Lake Ohrid (Macedonia/Albania): testing diatom response to climate

Lake Ohrid is a site of global importance for palaeoclimate research. This study presents results of diatom analysis of a ca. 136 ka sequence, Co1202, from the northeast of the lake basin. It offers the opportunity to test diatom response across two glacial-interglacial transitions and within the Last Glacial, while setting up taxonomic protocols for future research. The results are outstanding in demonstrating the sensitivity of diatoms to climate change, providing proxy evidence for temperature change marked by glacialinterglacial shifts between the dominant planktonic taxa, Cyclotella fottii andC. ocellata, and exact correlation with geochemical proxies to mark the start of the Last Interglacial at ca. 130 ka. Importantly, diatoms show much stronger evidence in this site for warming during MIS3 than recorded in other productivity-related proxies, peaking at ca. 39 ka, prior to the extreme conditions of the Last Glacial maximum. In the light of the observed patterns, and from the results of analysis of early Holocene sediments from a second core, Lz1120, the lack of a response to Late Glacial and early Holocene warming from ca. 14.7–6.9 ka suggests the Co1202 sequence may be compromised during this phase. After ca. 7.4 ka, there is evidence for enhanced nutrient enrichment compared to the Last Interglacial, followed by a post-Medieval loss of diversity which is consistent with cooling, but not definitive. Taxonomically, morphological variability in C. fottii shows no clear trends linked to climate, but an intriguing change in central area morphology occurs after ca. 48.7 ka, coincident with a tephra layer. In contrast, C. ocellatashows morphological variation in the number of ocelli between interglacials, suggesting climatically-forced Correspondence to: J. M. Reed (j.m.reed@hull.ac.uk) variation or evolutionary selection pressure. The application of a simple dissolution index does not track preservation quality very effectively, underlining the importance of diatom accumulation data in future studies.

Oxygen isotope analysis of diatom silica and authigenic calcite from Lake Pinarbasi, Turkey

There is increasing interest in the 18O/16O ratio of diatom silica, particularly for lakes where carbonates are absent. Here we compare the 18O/16O ratios preserved in diatom silica and authigenic calcite from an open, spring-fed, freshwater lake core from Turkey which spans marine oxygen isotope stage 3. The two sets of isotope data show contrasting trends in spite of their mutual dependence on the water 18O/16O ratio and lake-water temperature. The most likely explanation for this divergence is difference in seasonality of biological productivity mediated by the strongly continental climate of the Anatolian plateau. Diatom silica and authigenic calcite are precipitated from solutes in the lake-water at different times of the year. Diatom productivity follows a well-defined seasonal cycle, peaking first and most importantly in the spring and then in the autumn. The precipitation of calcite follows productivity by all forms of photosynthetic organisms that deplete CO2 but in most lakes this occurs during the summer months. The δ18Ocalcite curve shows mean summer temperature maxima at ca. 30–35 and ca. 58 ka BP while the intervening data represent a period of relatively cool summers. The δ18Odiatom curve shows bipolar results (15–20 and 29–33‰), which suggests that at least two discrete sources or processes contributed to the oxygen composition of the diatoms but probably involved a dilution mechanism to shift the isotopic values. The most likely source of depleted water is from snow entering the lake during the spring thaw. We infer that many authigenic calcite curves from regions with markedly seasonal climates may be temporally limited to a few summer months and that diatom silica provides complementary data on seasonally-specific water isotopic composition rather than a substitute for analyses based on carbonate.

More Than One Million Years of History in Lake Ohrid Cores

Continental scientific drilling is an important tool for exploring natural and anthropogenic processes on Earth. In past decades the results obtained from lake drilling projects contributed significantly to a better understanding of short-term and long-term climate change and natural hazards.

Coastal Evolution in a Mediterranean Microtidal Zone: Mid to Late Holocene Natural Dynamics and Human Management of the Castelló Lagoon, NE Spain.

We present a palaeoenvironmental study of the Castelló lagoon (NE Spain), an important archive for understanding long-term interactions between dynamic littoral ecosystems and human management. Combining geochemistry, mineralogy, ostracods, diatoms, pollen, non-pollen palynomorphs, charcoal and archaeo-historical datasets we reconstruct: 1) the transition of the lagoon from a marine to a marginal environment between ~3150 cal BC to the 17th century AD; 2) fluctuations in salinity; and 3) natural and anthropogenic forces contributing to these changes. From the Late Neolithic to the Medieval period the lagoon ecosystem was driven by changing marine influence and the land was mainly exploited for grazing, with little evidence for impact on the natural woodland. Land-use exploitation adapted to natural coastal dynamics, with maximum marine flooding hampering agropastoral activities between ~1550 and ~150 cal BC. In contrast, societies actively controlled the lagoon dynamics and become a major agent of landscape transformation after the Medieval period. The removal of littoral woodlands after the 8th century was followed by the expansion of agrarian and industrial activities. Regional mining and smelting activities polluted the lagoon with heavy metals from the ~11th century onwards. The expansion of the milling industry and of agricultural lands led to the channelization of the river Muga into the lagoon after ~1250 cal AD. This caused its transformation into a freshwater lake, increased nutrient load, and the infilling and drainage of a great part of the lagoon. By tracking the shift towards an anthropogenically-controlled system around ~750 yr ago, this study points out Mediterranean lagoons as ancient and heavily-modified systems, with anthropogenic impacts and controls covering multi-centennial and even millennial timescales. Finally, we contributed to the future construction of reliable seashell-based chronologies in NE Spain by calibrating the Banyuls-sur-Mer ΔR offset with ceramic imports from the Emporiae archaeological site.

Late Pleistocene Rodent Dispersal in The Balkans

The paper is focused on the zoogeographical relations of Late Pleistocene mammalian faunas from the Balkans, and in particular on the issue of whether direct mammalian dispersal between Anatolia and the Balkan Peninsula across the Aegean island arcs and the Bosphorus-Dardanelles region made a significant contribution to Balkan biodiversity. The study is based on micromammals, and more precisely on rodent species from selected local faunas which date from around the penultimate glacial cycle. During this period the Recent fauna of the Balkans became essentially established and rodent taxa can be mostly referred to the extant species. The paper does not deal with fossil sites from the northernmost Balkan region (Slovenia to northern Romania).