Abstract Neoichnological research of terrestrial tracemakers in coastal settings provides important palaeoenvironmental information about their context within the subaerial facies. Here we present the first geophysical dataset of reptile burrows in a carbonate substrate and use it to help visualize parts of the burrows of the Bahamian (San Salvador) rock iguana ( Cyclura rileyi ). High-resolution 800 MHz ground-penetrating radar (GPR) images within an enclosure on San Salvador Island were employed to discriminate between the electromagnetic signal response from subsurface anomalies related to air-dominated voids or live animals within burrows. The dielectric contrast between the carbonate substrate and open burrows was sufficient to identify the majority of the 15–20 cm-wide subsurface extensions of the inclined tunnels in the upper 30–40 cm. Whereas limestone clasts induced some interference, it is possible to differentiate their high-amplitude diffractions from those produced by the iguana burrows. Our research indicates that GPR imaging is a viable, rapid, non-invasive method of visualizing animal burrows, with implications for neoichnology, palaeoichnology, and conservation ecology of semi-fossorial species. Furthermore, the critically endangered status of Bahamian land iguanas, as well as ongoing threats from natural and introduced pressures, highlights the need for research into their ichnological record.

Hydromorphological and hydroclimatic methods were used to reconstruct the former surface runoff from the East European part of the Black Sea drainage basin. Data on the shape and dynamics of the last Fennoscandian ice sheet were used to calculate meltwater supply to the headwaters of the Dnieper River. The channel width and meander wavelength of well-preserved fragments of large paleochannels were measured at 51 locations in the Dnieper and Don River basins (East European Plain), which allowed reconstruction of the former surface runoff of the ancient rivers, as well as the total volume of flow into the Black Sea, using transform functions. Studies of the composition of fossil floras derived from radiocarbon-dated sediments of various origins and ages make it possible to locate their modern region analogues. These analogues provide climatic and hydrological indexes for the Late Pleniglacial and Late Glacial landscapes. Morphological, geological, geochronological, and palynological studies show that the landscape, climatic, and hydrologic history of the region included: (1) a cold and dry interval close to the Last Glacial Maximum characterized by high meteoritic surface runoff supplemented by meltwater flow from ice-dam lakes; (2) a warmer humid interval at the end of the Late Pleniglacial with very high surface runoff and formation of extremely large meandering channels, combined with a short event of substantial inflow from the Caspian Sea; and (3) a period from the Oldest Dryas to the Preboreal of nonsteady surface runoff decrease, and transformation of large meandering channels into smaller ones against the background of climate warming.

This paper describes the relationship between sea levels and climate based on the links between sea-level variations and river runoff. During the final late Pleistocene and postglacial periods, the Caspian Sea fluctuated between regression and transgression stages. The Black Sea experienced fluctuations as well, but these were mainly controlled by the world ocean due to water exchange through the Bosporus Strait. Sometimes, the Caspian Sea overflowed into the Black Sea through the Manych Strait, and they periodically coalesced. Change in the level of both seas could be interpreted as responses to the regional-scale water budget (the balance between inflow and outflow components). These components can be calculated from atmospheric general circulation models. This approach uses climate modeling data to reproduce river runoff changes, and, consequently, variations in seawater and sea level under contrasting climate conditions. In response to glacial conditions of the last cold Pleistocene event, the lowering levels of the Black Sea (post-Karangatian regression stage) and the Caspian Sea (Atelian regression stage) are simulated simultaneously. This lends credence to the idea of the connection between deep regression states of the Caspian and Black Seas and mature stages of the late Quaternary glacial/cooling/drying planetary events. Analysis of observed information allows us to conclude—taking into account the uncertainties of reconstructed data—that at least two regression stages occurred simultaneously with late Quaternary glacial planetary events. The simulation of transgression stages (their onset and duration) remains a very difficult problem. Results of modeling have shown that during the warm periods (taking as examples the mid-Holocene and Allerød events), simulated river runoff did not increase to the extent needed for a strong transgression and overflow of the Caspian Sea into the Black Sea through the Manych Strait. Thus, there is no clear understanding about the source of “additional” water volume necessary to elevate the level of the Caspian Sea to a point that would permit overflow into the Black Sea.

This paper presents geophysical and core data obtained from several marine geology surveys carried out in the western Black Sea. These data provide a solid record of water-level fluctuation during the Last Glacial Maximum in the Black Sea. A Last Glacial Maximum lowstand wedge evidenced at the shelf edge in Romania, Bulgaria, and Turkey represents the starting point of this record. Then, a first transgressive system is identified as the Danube prodelta built under ~40 m of water depth. The related rise in water level is interpreted to have been caused by an increase in water provided to the Black Sea by the melting of the ice after 18,000 yr B.P., drained by the largest European rivers (Danube, Dnieper, Dniester). Subsequently, the Black Sea lacustrine shelf deposits formed a significant basinward-prograding wedge system, interpreted as forced regression system tracts. On top of these prograding sequences, there is a set of sand dunes that delineates a wave-cut terrace-like feature around the isobath −100 m. The upper part of the last prograding sequence is incised by anastomosed channels that end in the Danube (Viteaz) canyon, which are also built on the lacustrine prograding wedge. Overlying this succession, there is a shelfwide unconformity visible in very high-resolution seismic-reflection profiles and present all over the shelf. A uniform drape of marine sediment above the unconformity is present all over the continental shelf with practically the same thickness over nearby elevations and depressions. This mud drape represents the last stage of the Black Sea water-level fluctuation and is set after the reconnection of this basin with the Mediterranean Sea.

The investigation of rapid sea-level and climate change is critical to understanding the geologic history of the Black Sea and its effect on ancient civilizations of the region and adjacent areas. The current consensus of western scientists is that only local sea-level curves may be constructed because of local-to-regional changes in sedimentation, tectonics, and other factors. Recently, however, I.P. Balabanov published a synoptic sea-level curve for the entire Black Sea that spans the Pleistocene-Holocene transition and the Holocene based on older radiocarbon dates. This curve has been heavily criticized and is viewed skeptically by western workers for the reasons already mentioned as well as the use of questionable methodologies. Here, we examine Balabanov's curve in light of these criticisms by comparing his sea-level curve to other independently derived sea-level and environmental indices. We find that, despite its drawbacks, many of the fluctuations of the Balabanov curve coincide with repeated ocean-atmosphere reorganizations, which involve shifts from cool to warm phases and corresponding changes in the species composition of foraminiferal assemblage ecozones, precipitation, and runoff. We suggest that following the initial invasion of the Black Sea by marine Mediterranean waters during the Pleistocene-Holocene transition, climatic amelioration (warming) following each cool phase of an ocean-atmosphere reorganization resulted in shifting precipitation patterns that produced repeated, rapid freshwater discharges into the Black Sea from surrounding rivers. In this scenario, runoff following each reorganization temporarily altered the species composition of foraminiferal assemblages, as noted in earlier studies. Freshwater discharges during the Holocene were likely lower than those envisioned by Balabanov but may have affected sea level sufficiently to alter coastal geomorphology and coastal aquifers rapidly, while causing the translocation of settlements from areas where submarine archaeological sites are now situated. Sea-level and climate change during the Pleistocene-Holocene transition may have been similar to that of the Holocene, but greatly amplified.

The problem of formation of the Black and Caspian Sea sea-level regime, which is considered as a component of Earth climate, is addressed through a time series of parameters for the past 200 years. To analyze the variables in sea-level changes, we applied modern methods of statistical processing: correlation, spectral and singularity analyses, and the wavelet analysis, among others. Using this approach, we prove that changes in climatic and hydrological parameters at global and regional scales are directly or indirectly reflected in sea-level regime. Based on statistical output, we propose a scenario of climatic sea-level changes for the short- and long-term future (until the end of 2100).

Analyses of marine sediment lithology, paleorelief, and depositional environments on the northwestern Black Sea shelf were used for paleogeographic reconstructions reflecting the time periods of 30–25 ka, 15.5–15 ka, 11–10 ka, 9 ka, and 4 ka. The landscape of 25 ka, when sea level was 87 m below present, consisted of three geomorphic elements: (1) a denudation plain incised by numerous rivers and uniformly dipping southward, (2) a late Pleistocene alluvial terrace plain, within which the valleys of the Dnieper, Dniester, and Danube formed a common alluvial plain, and (3) a low coastal delta plain. The subsequent sea-level rise of the Neoeuxinian sea-lake to −55 m (15.5–15 ka) and −37 m (11–10 ka) resulted in the flooding of deltaic lowlands and a large portion of the alluvial terrace plain containing the deeply embayed Dniester and Dnieper limans. After the Drevnechernomorian transgressive phase at 9 ka, the sea flooded almost the entire late Pleistocene alluvial terrace plain, and the Dniester and Dnieper limans were converted to open marine embayments. Through Kalamitian time (4 ka), the entire Chilia section of the Danube delta was flooded. A large tract of land existed in the region of the Tendra Spit and Odessa bank. Around 25 ka, forest landscapes were common for the highlands and valley slopes of rivers and gullies. A steppe zone occupied the alluvial plain, which dominated the landscape to the south. This study demonstrates that paleogeographic reconstructions may serve as a basis for (1) locating submerged ancient settlements and (2) constraining possible migration routes.

Previous palynological studies of the Caspian–Black Sea–Mediterranean corridor primarily focused on pollen and spores for paleoecological and chronostratigraphic studies. Until recently, there has been less emphasis on the nonpollen palynomorphs, such as dinoflagellate cysts, algal and fungal spores, and animal remains. New studies of nonpollen palynomorphs in land-locked seas, estuaries, and lakes reported here indicate that they are important markers of salinity, nutrient loading, and human activity, including ballast discharge, farming, and soil erosion. We describe the nonoxidative laboratory processing methods necessary to extract nonpollen palynomorphs from marine- and brackish-water sediment samples. We list 48 nonpollen palynomorphs taxa from 37 surface sediments (including the past millennium) for cores along the salinity gradient from <16‰ off the Danube Delta to >39‰ in the Aegean, Mediterranean, and Red Seas, for two Crimean saline lakes, the Caspian and Aral Seas, and for lakes in Iran and Kazakhstan. The main nonpollen palynomorphs taxa are illustrated and listed systematically to provide a baseline for future collaborative studies among Black Sea corridor palynologists. We outline the biological affinities of some nonpollen palynomorphs and discuss the initial results of the study in terms of what nonpollen palynomorphs may reveal about the history of the salinity in the Black Sea corridor and the impact of humans on soil erosion, plankton production, and harmful algal blooms.

Pollen and lithopedological data were obtained from Upper Paleolithic sites and Upper Pleistocene loess-soil sequences located between the Sea of Azov and the River Donets, and in the foothills of the Crimean Mountains. During the last Middle Pleniglacial interstadial (Upper Vytachiv soil, 30–27 ka), there existed boreal steppe (south-boreal forest-steppe in Crimea). During the Late Pleniglacial, two main phases of loess accumulation occurred, which were separated by the phase of initial pedogenesis. The loess accumulated under subperiglacial xeric steppe (particularly dry at 15–13 ka), and the incipient soils (Dofinivka unit, 18–15 ka) formed under boreal grassland. During the Late Glacial interstadials, there existed boreal and south-boreal forest-steppe with a relatively wet climate (middle Prychernomorsk soil unit, the upper soil 11.8–11.4 ka). During the Younger Dryas, grassland reappeared under a dry and cool climate (10.9–10.5 ka). Paleoclimatic changes demonstrate the same pattern in both studied areas, and they correspond well with Black Sea transgressive-regressive cycles. Regional differences still existed—during all phases, the climate was the mildest in the western foothills of the Crimean Mountains, the coldest in the Donetsk Upland, and the driest near the Sea of Azov.

We discuss pollen, soil, geomorphologic, and archaeological records used for reconstructing climatic, biogeographic, and human-environment events in the Crimean Peninsula during the past 130 k.y. Warm and moist conditions conducive to forest growth prevailed during the Eemian Interglacial (marine isotope stage [MIS] 5e). Although sea levels were higher than at present, a review of the stratigraphic and geomorphic data suggests that the peninsula was not detached from the mainland. During the last glacial period (MIS 5d–MIS 2), conditions fluctuated between steppe and tree growth in warmer places during the stadials, and forest-steppe during the interstadials. The Pleistocene–Holocene transition involved forest growth during the Bølling-Allerød interstadials, steppe during the Younger Dryas, and a forest-steppe during the early Holocene. The establishment of the modern Black Sea ca. 7 ka and increasing temperatures led to the formation of the modern vegetation belts, ushering in optimal conditions for the establishment of Neolithic communities. A dry period peaked around 4–3.5 ka, followed by milder conditions that lasted until the colonization of Crimea by Greek farmers during the middle part of the first millennium A.D. Dry conditions at the end of the same millennium led to the abandonment of agriculture and settlement decline. Sea-level oscillations during the late Holocene had an important effect on shoreline configuration, lagoonal systems, coastal wetlands, and human settlements. Data used in this paper were drawn from a number of published papers, mostly in Russian and Ukrainian, as well as records produced by the authors' research.

The Black Sea basin presents an ideal laboratory for investigations of morphodynamic interplay between response (morphology) and force (processes) associated with shelf sedimentation. Recent studies along the perimeter of the basin have documented the existence of a complex, heterogeneous seafloor varyingly composed of sand, gravel, silt, and clay. Side-scan sonar data are utilized to establish the spatial patterns of bedform types in the area. In addition, a benthic tripod, configured with an acoustic Doppler current profiler, a rotary fanbeam sonar, and a conductivity-temperature sensor was deployed to record seabed dynamics in response to changing forcing conditions. Together, the tripod and side-scan survey data sets provide a complementary basis for deciphering the processes responsible for the observed seafloor morphology. The side-scan sonar data allows for the determination of spatial patterns of bedform length and orientation. In total, 2376 individual large sand wave bedforms were digitized in geographic information systems with mean and modal wavelengths of 72.8 and 15.7 m respectively. The correlation of near-inertial waves (velocity amplitude 12–20 cm/s and period 12–16 h) and bedform geometry suggest that the extensive sand-wave patches imaged across the shelf are affected by active modern processes and may themselves be modern features or perhaps relict features that remain active presently. Progressive vector diagrams of the nearbed mean current flow indicate a component of cross-shelf directed flow, suggesting an enhanced potential for artifact preservation via cross-shelf advection of anoxic bottom waters by the near-inertial flows measured in this study.

The August 2007 expedition to the Black Sea continued a multiyear project designed to locate and study ancient shipwrecks in deep water. The expedition revisited and investigated two shipwrecks, Sinop D (at 325 m depth off Sinop, Turkey) and Chersonesos A (at 135 m depth off Sevastopol, Ukraine). These wreck sites are good case studies for our research because they are located in different parts of the Black Sea, in anoxic and suboxic waters, respectively. Preliminary data reported here are from seawater samples taken from around the wrecks and a year-long collection of temperature, salinity, and pressure data. Trace-element data from the seawater samples are consistent with reported processes and values for the Black Sea. The oceanographic sensor data confirm the stagnant nature of the anoxic water layer that has allowed for the high level of preservation of the Sinop D wreck site. We also discuss the design and placement of two sets of experiments left in situ to characterize the decay rates of common materials found on ancient shipwrecks, including wood and metal. By providing ways to understand the chemical and physical processes that characterize different parts of the Black Sea water column, these wrecks are important sites for (1) determining the preservation potentials of cultural materials in deep water, and (2) informing the design of methodologies necessary to conserve them.

An accurate chronology for the exchange of aquatic species between water basins is important for paleoenvironmental reconstruction on both regional and continental scales. During the early Holocene, the range of zebra mussels, Dreissena polymorpha , was limited to the Black, Azov, Caspian, and Aral Seas, as well as the estuaries and lower and middle reaches of the Pontic-Caspian rivers. We present new findings that challenge the currently held view that this species migrated into the Baltic Sea watershed during the early 1800s through the canals joining the tributaries of rivers that drain into the Black and Baltic Sea basins. Geological investigations along the southeast Baltic Sea coast (Curonian and Vistula spits and lagoons) have uncovered shells of D. polymorpha that yielded radiocarbon ages older than 1000 radiocarbon yr B.P. We propose two scenarios to explain the new radiocarbon dates for D. polymorpha . The first scenario involves an anomalously large reservoir effect—as large as 600–800 yr—however, several lines of evidence cast doubt upon the validity of such a large reservoir correction. The second scenario that might explain the old zebra mussel ages is the earlier arrival of Dreissena polymorpha into the Baltic region. Natural exchange may have been facilitated by the proximity of the tributaries draining the Pontic and Baltic watersheds. Human-mediated transport is also considered in association with Viking voyages from the Baltic to the Black and Caspian Seas between A.D. 800 and 1000, and the riverine trade exchange during the Lithuanian expansion into the Pontic steppe in subsequent centuries. It is likely that both scenarios played a role, with implications for late Holocene biogeography and paleoecology of the Pontic-Caspian and Baltic basins.