The development of northern Sylt during the Latest Holocene

Abstract

Former stages of the morphological development of northern Sylt are reconstructed to extend knowledge of the type and approximate time of the formation of a sandy bay (K6nigshafen) in the Wadden Sea. Apart from an analysis of historical maps and nautical charts, this paper includes the representation of the results of recent borings and sedimentological findings. The two ways of tracing back the development led to different conclusions, which are discussed. The cartographical conclusions cannot confirm the assumption that Kbnigshafen was a deep bay. The input of dune sand from westerly directions and the formation of a sand spit system from the south have caused great morphological changes up to present times. Since the middle of the 17th century there has been an extension of the Kbnigshafen area. On the other hand, geological investigations show that the Ellenbogen could have been formed between the middle of the 17th century and the end of the 18th century. Before that, Kbnigshafen was sheltered by a large sandy spit directly at the Lister Tief. It might have been the location of the famous sea battle of 1644 between the Danish fleet and a Swedish/Dutch fleet. The Kbnigshafen area is possibly a young formation and is, at least since its separation from the Lister Tief by the Ellenbogen, an area of prevailing sedimentation.

Transitions in sandflat biota since the 1930s: effects of sea-level rise, eutrophication and biological globalization in the tidal bay Königshafen, northern Wadden Sea

“…The shape of Königshafen has changed little over the past century except for the embankment of a salt marsh area in the south in 1937 and a peninsula created by nourished sand 70 years ago (Kolumbe 1932;Newig 1980;Bayerl and Hilgelke 1994). Although most of the shores show signs of retreat by erosion, the rate is rather small.…”

How an introduced seaweed can affect epibiota diversity in different coastal systems

“…Tides are semi-diurnal with an average tidal range of about 2 m. Salinity usually remains between 30 and 32 psu. A detailed description of the hydrography, geology, sediments and biota of the study area is given by Reise (1985), Austen (1994a, b), Bayerl and Higelke (1994) and Ga¨tje and Reise (1998). Assemblages of macroalgae are scarce on the sedimentary tidal flats where F. vesiculosus presents the only abundant native habitat-providing seaweed.…”

Habitat-specific size structure variations in periwinkle populations (Littorina littorea) caused by biotic factors

“…Detailed descriptions of the geology, hydrography and sediments of the study area are given by Reise (1985), Austen (1992Austen ( , 1994a, Bayerl and Higelke (1994) and . In the Wadden Sea, periwinkles L. littorea reach highest densities on mixed epibenthic aggregations of the non-indigenous PaciWc oyster Crassostrea gigas (Thunberg) and the native blue mussel Mytilus edulis L. which represent preferred habitats for periwinkles because bivalve aggregations provide an appropriate attachment substratum and suitable food conditions.…”