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Two unique Pre-Viking Age ship burials were found from Salme village, Saaremaa Island, eastern Baltic Sea, containing remains of seven men in the smaller and 34 men in the larger ship. According to the archaeological interpretations, these ships belonged to a viking crew possibly from the Stockholm-Mälaren region, eastern Sweden. Geoarchaeological research was conducted in the area to reconstruct Late-Holocene relative sea-level (RSL) changes and shoreline displacement to provide environmental context to these burials. In this paper we present a Late-Holocene shore displacement curve for the Saaremaa Island and GIS-based palaeogeographic reconstructions for the Salme area. The curve shows an almost linear RSL fall from 5.5 to 0.8 m a.s.l. between 1000 BC and 1300 AD with an average rate of 2 mm/year. A slowdown in regression may be attributed to accelerated sea-level rise after the Little Ice Age and during the industrial period, being consistent with the tide-gauge measurements from the 20th century. Palaeogeographic reconstructions indicate the existence of a strait in the Salme area during the burial of the ships. The eastern part of the strait with water depth up to 2.8 m was about 80–100 m wide. The relatively steep and wind-protected shores in that part of the strait were probably the best places in the area for landing the viking ships. According to sedimentological evidence and diatom data, the narrowing of Salme palaeostrait occurred between 1270 and 1300 AD. Salme I and II ships were buried at 650–770 AD into the sandy-gravelly coastal deposits which had accumulated there in the open coastal zone about 710–450 years earlier. Reconstructions show that the ships were located about 2–2.5 m above coeval sea level and more than 100 m from the coastline. Thus, both ships were probably moved from the shore to the higher ground for burial. [ABSTRACT FROM AUTHOR]

The ringed seal (Pusa hispida) is an early immigrant in the Baltic Basin and has since its arrival experienced substantial changes in the climate, salinity and productivity of the Basin. In this paper, we discuss the dispersal and distribution of the ringed seal during different stages of the Baltic Sea in relation to past and ongoing environmental changes. Subfossil ringed seal remains around the Baltic Sea and the Danish Straits were radiocarbon dated in order to map the distribution of the species in different time periods. The δ13C data were used in evaluating the changes in the marine character of the Baltic Basin. The sequence of the dates indicates a continuous presence of the species in the Baltic Basin. The earliest ringed seal finds come from the Skagerrak/Kattegat area (Denmark, Swedish west coast) and date to the full glacial period and Baltic Ice Lake. In the Baltic Basin, the species appears in the subfossil record during the Ancylus period, but the main part of the remains date to the Littorina stage. During the Littorina stage, the distribution of the species was at least periodically wider than today, covering also southern parts of the Baltic. The presence of breeding populations in southern parts of the Baltic during the Holocene Thermal Maximum (HTM) indicates that the winters were at least periodically cold enough for winter ice. The changes in the marine influence in the Baltic Basin can be seen in the seal collagen δ13C values, which serve as a proxy for qualitative changes in water mass salinity. [ABSTRACT FROM AUTHOR]

While it is acknowledged that an incorrect age datum was used to construct the depth–age relationship for the lower part of the core in question, the conclusions of the paper, which related to salinity changes of the last 10 000 years, are unaffected. [ABSTRACT FROM AUTHOR]

Lacustrine sediments retain Cladocera (Crustacea) subfossils (carapaces, ephippia, head shields, and postabdomens) from the Holocene, which allows reconstructing past aquatic communities and environmental changes. In late Holocene (Subatlantic) fossils, among many Cladocera species, we noticed the appearance of several Bosmina (Eubosmina) species in lakes surrounding the Baltic Sea. These species were never recorded in the early Holocene. The appearance of these species is a record of very recent speciation, which took place during the last millennium in lakes surrounding the Baltic Sea. Contemporary data show co-occurrence of several Bosmina (Eubosmina) species (longispina, kessleri, reflexa, ruehei, coregoni, gibbera, thersites). These species are not a product of invasion or introgressive hybridization, but in fact, they are probably a product of speciation. Here, we present the palaeolimnological evidence of this speciation from the only one species, Bosmina (Eubosmina) longispina, found in lacustrine sediments from the last interglacial and glacial periods. [ABSTRACT FROM PUBLISHER]

To investigate the Holocene vegetation history and shoreline displacement along the southeastern Swedish coast, two radiocarbon dated pollen, macrofossil and mineral magnetic sequences were studied in the western Blekinge coast: Hunnemara Lake and Smygen Bay. Both pollen records show mosaic vegetation with grasslands, heaths and woodlands prior to 11 300 cal. BP. Pinus -dominated mixed forest was initially established by 11 000 cal. BP. By 10 000 cal. BP, mixed forest with higher species diversity was fully established. Expansion of broad-leaved trees began at about 8600 cal. BP, indicating the onset of the mid-Holocene thermal maximum in Scandinavia. Following the Ulmus decline 5800 cal. BP, the regional forest became much more open due to increased human disturbance. Both basins were isolated during the period of 11 300 – 11 000 cal. BP, and subsequently in contact with the Ancylus Lake between 10 700 and 9800 cal. BP. Low abundance of brackish-water diatoms at Smygen suggests that this basin was connected with the Baltic Sea between 9800 and 8600 cal. BP, corresponding to the Early Littorina Sea phase. Hunnemara was isolated during this period. The two basins were in turn flooded at 8600 and 8300 cal. BP, as a result of global sea-level rise. A sedimentary hiatus (8300 – 7500 cal. BP) was present at Hunnemara, probably caused by a rapid sea-level rise related to global meltwater pulse 3. Aquatic macrofossil and mineral magnetic proxies reveal several minor transgressions at both sites, probably regulated by centennial-scale variations in regional storminess. Hunnemara was isolated from the Baltic Basin by 3100 cal. BP, concurrent with a lowering of the sea level at Smygen. [ABSTRACT FROM AUTHOR]

Sediment cores from the Gotland Basin were studied for their siliceous microfossil assemblages and organic carbon content to compare recent environmental changes in the Baltic Sea with its natural long-term history. Age models were constructed using 210 Pb, 137 Cs and corrected and calibrated 14 C dates. The transgression that marks the onset of the Ancylus Lake stage is recorded in the sediments as a small increase in organic carbon coinciding with a peak in diatom abundance and increased diatom diversity. A minor occurrence of brackish-freshwater diatoms is recorded in the Ancylus Lake c. 9950–9750 cal. yr BP (c. 8900–8800 14 C yr BP), correlating with the onset of the Initial Litorina Sea in the Bornholm Basin. A high-productivity event is recorded in the end of the Post-Litorina Sea and corresponds to the Mediaeval warm event. An alteration in the diatom assemblage contemporaneous with a decrease in organic carbon, interpreted as representing a deterioration in the climate, correlates with the start of the ‘Little Ice Age’ about 850–700 cal. yr BP. A change dated to ad 1950–1960 is probably an effect of increased nutrient availability in the open Baltic Sea. This effect of eutrophication was probably caused by increased discharge of nutrients deriving from fertilizers, as the responding diatom species partly indicate a cold climate rather than a warm one, as would have been expected if this had been only a response to the warmer climate documented during the last 100 years or so. [ABSTRACT FROM AUTHOR]

Four short sediment cores from the southwestern Baltic Sea were analysed with respect to their content of siliceous microfossils. The aim was to detect and date changes in the composition of the diatom flora and to link these changes to variations in the anthropogenic load of nutrients during the last century. The study shows that the most significant change in the diatom assemblages occurred 130–140 years ago. The change is recorded in the sediments as a shift from periphytic diatom taxa to a predominance of planktonic taxa. This indicates that the photic layer has decreased in depth, probably due to eutrophication of the Baltic Sea, which consequently began to affect the area investigated approximately ad 1850. To support the results of a changing ratio of periphytic to planktonic diatoms, diatom accumulation rates were calculated. In general, the diatom accumulation rate data show a decrease in the periphytic accumulation rates and an increase in the planktonic accumulation rates towards the sediment surface. Some indications of a colder climate are recorded in the sediments approximately 230 years ago. These results are in accordance with the record of maximum extent of sea ice in the same area and are suggested to represent a late stage in the ‘Little Ice Age’. [ABSTRACT FROM AUTHOR]

Studies of plant and animal macrofossils have been carried out on early-Holocene lake marls from the southwestern Baltic. The records have been dated to the interval from c. 8500 to 7800 14 C years BP by correlating pollen assemblages to an onshore radiocarbon dated pollen diagram. The sediments contain from 5 to 81% carbonate, and only few macroscopic remains of wetland and terrestrial taxa. The plant and animal (mainly mollusc) macrofossils reflect deposition at the outer edge of the belt with submerged macro-limno-phytes, in the lower littoral, perhaps at water depths at 4–7 m. The ratio between the shells and opercula of the snail Bithynia tentaculata points to some post-mortem disturbance, but it can be concluded that the water was highly alkaline and mesotrophic. [ABSTRACT FROM AUTHOR]