Early Holocene shore‐displacement in southern central Sweden as recorded in elevated isolated basins

Hedenström, Anna; Risberg, Jan

doi:10.1111/j.1502-3885.1999.tb00236.x

Cited by 15 publications

(13 citation statements)

References 24 publications

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“…In the Gulf of Bothnia area, in the northernmost part of the Baltic, this change was delayed by c. 500 years (Eronen 1974). A delay of the same duration has been found in studies of sea-level history in central Sweden (Hedenström & Risberg 1999).…”

Section: Mastogloia Phase and Litorina Sea Stagesupporting

confidence: 71%

Rates of Holocene isostatic uplift and relative sea‐level lowering of the Baltic in SW Finland based on studies of isolation contacts

Eronen¹,

Glückert

Hatakka³

et al. 2001

Boreas

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Southwestern Finland was covered by the Weichselian ice sheet and experienced rapid glacio‐isostati c rebound after early Holocene deglaciation. The present mean overall apparent uplift rate is of the order of 4–5 mm/yr, but immediately after deglaciation the rate of crustal rebound was several times higher. Concurrently with land uplift, relative sea level in the Baltic basin during the past more than 8000 years was also strongly affected by the eustatic changes in sea level. There is ample evidence from earlier studies that during the early Litorina Sea stage on the southeastern coast of Finland around 7000 yr BP (7800 cal. yr BP), the rise in sea level exceeded the rate of land uplift, resulting in a short‐lived transgression. Because of a higher rate of uplift, the transgression was even more short‐lived or of negligible magnitude in the southwestern part of coastal Finland, but even in this latter case a slowing down in the rate of regression can still be detected. We used evidence from isolation basins to obtain a set of 71 14C dates, and over 30 new sea‐level index points. The age‐elevation data, obtained from lakes in two different areas and located between c. 64 m and 1.5 m above present sea level, display a high degree of internal consistency. This suggests that the dates are reliable, even though most of them were based on bulk sediment samples. The two relative sea‐level curves confirm the established model of relatively gradually decreasing rates of relative sea‐level lowering since c. 6100 yr BP (7000 cal. yr BP) and clearly indicate that the more northerly of the two study areas experienced the higher rate of glacio‐isostati c recovery. In the southerly study area, changes in diatom assemblages and lithostratigraphy suggest that during the early Litorina Sea stage (8300–7600 cal. yr BP) eustatic sea‐level rise exceeded land uplift for hundreds of years. Evidence for this transgressio n was discovered in a lake with a basin threshold at an elevation of 41 m above sea level, which is markedly higher than any previously known site with evidence for the Litorina transgression in Finland. We also discuss evidence for subsequent short‐term fluctuations superimposed on the main trends of relative sea‐level changes.

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Section: Mastogloia Phase and Litorina Sea Stagesupporting

confidence: 71%

Rates of Holocene isostatic uplift and relative sea‐level lowering of the Baltic in SW Finland based on studies of isolation contacts

Eronen¹,

Glückert

Hatakka³

et al. 2001

Boreas

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“…This result indicates that dispersal events that transported marine taxa from the sea were more frequent to the lake in closer proximity to the sea compared with the other two lakes, which were either located in the mountains or close to the Swedish Baltic Sea coast, which is a brackish environment. An alternative explanation to our result is that lake Lille Jonsvatn was previously below sea level (Reite, 1983;Hedenströ m and Risberg, 1999); that is, before ancient displacement of the Norwegian seashore line (B8000 years ago), and marine bacteria may have remained in the lake since then. This explanation, however, seem unlikely, especially for the sediments, since we only used surface sediments which were much more recently formed.…”

Section: Discussionmentioning

confidence: 67%

Can marine bacteria be recruited from freshwater sources and the air?

et al. 2014

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There is now clear evidence that microorganisms present biogeographic patterns, yet the processes that create and maintain them are still not well understood. In particular, the contribution of dispersal and its exact impact on local community composition is still unclear. For example, dispersing cells may not thrive in recipient environments, but may still remain part of the local species pool. Here, we experimentally tested if marine bacteria can be retrieved from freshwater communities (pelagic and sediment) and the atmosphere by exposing bacteria from three lakes, that differ in their proximity to the Norwegian Sea, to marine conditions. We found that the percentage of freshwater taxa decreased with increasing salinities, whereas marine taxa increased along the same gradient. Our results further showed that this increase was stronger for lake and sediment compared with air communities. Further, significant increases in the average niche breadth of taxa were found for all sources, and in particular lake water and sediment communities, at higher salinities. Our results therefore suggests that marine taxa can readily grow from freshwater sources, but that the response was likely driven by the growth of habitat generalists that are typically found in marine systems. Finally, there was a greater proportion of marine taxa found in communities originating from the lake closest to the Norwegian Sea. In summary, this study shows that the interplay between bacterial dispersal limitation and dispersal from internal and external sources may have an important role for community recovery in response to environmental change.

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“…These include several 11,400-11,300-yearold records for two sites (Lake Rummu and Rae Basin, now a bog), when they were part of the initial freshwater Yoldia Sea phase of the Baltic Sea basin, and several approximately 9,500-year-old records from calcareous silt in what was then a freshwater lagoon isolated from the Baltic Sea (Kõpu basin, Island of Hiiumaa), but now a bog. There is also a record in the early Holocene from the other side of the Baltic in south central Sweden (Hedenstr} om & Risberg, 1999). An undated post-Tertiary sand stained with peaty residue below a layer of alluvial soil not far from the mouth of a valley entering Loch Fine, Scotland, had a mixture of marine and freshwater species, including D. geminata (Gregory, 1857).…”

Section: Fossil Recordsmentioning

confidence: 95%

Biology of the freshwater diatom Didymosphenia: a review

2009

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Features of the colonial diatom Didymosphenia are reviewed, especially D. geminata. Although there is a long record of its occurrence in north temperate regions, mass growths have been reported much more widely in recent years. Contrary to some statements in the literature, there are also reliable older records for the southern hemisphere, though the first report of mass growth was in New Zealand in 2004. The annual cycle of morphological changes in D. geminata in northern England, and probably elsewhere, includes a winter period when motile cells are attached to the substratum followed by spring when stalks start to develop. These raise cells into the water column and provide a site for phosphatase activity. Environmental factors associated with success include absence of extreme floods, high light, pH above neutral and nutrient chemistry. D. geminata often, but not always, occurs in waters where the N:P ratio is high for much of the year, but the key factor is the ratio of organic to inorganic phosphate. D. geminata thrives where organic P is predominant and the overall P concentration is low enough for organic P to be an important P source. It is unknown whether organic N can be used. Environmental changes increasing the relative importance of organic P are likely to favour D. geminata. Likely examples are increased N:P due to atmospheric N deposition and changes in form and seasonality of P release from organic-rich soils due to climatic warming. The nutrient chemistry of deep water released from dams to rivers also needs investigation. To what extent are genetic changes occurring in response to environmental changes and are new ecotypes spreading round the world? In spite of many adverse reports about D. geminata, such as detached mats blocking water pipes, there is still doubt about the extent to which it causes problems, particularly for fish. There have been few adverse effects on migratory salmonids in Europe and North America, but at least one report of harm to a brown trout population in USA. In New Zealand, it has caused serious problems for water sports, although it remains open to question how much adverse effect it has had on fish populations. If the presence of microcystins in or associated with D. geminata, as indicated recently for two populations, proves to be widespread and at sufficiently high concentration, their possible accumulation in fish requires study. Where control is required, this could Handling editor: Pierluigi Viaroli be achieved by enhancing the ratio of inorganic to organic phosphate in the water early in the growth season. Practical ways to achieve this are suggested.

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Early Holocene shore‐displacement in southern central Sweden as recorded in elevated isolated basins

Cited by 15 publications

References 24 publications

Rates of Holocene isostatic uplift and relative sea‐level lowering of the Baltic in SW Finland based on studies of isolation contacts

Rates of Holocene isostatic uplift and relative sea‐level lowering of the Baltic in SW Finland based on studies of isolation contacts

Can marine bacteria be recruited from freshwater sources and the air?

Biology of the freshwater diatom Didymosphenia: a review

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