Holocene diatom biostratigraphy of the SW Gulf of Gdańsk, Southern Baltic Sea (part III)

Abstract

The palaeoenvironmental changes of the south-western part of the Gulf of Gdańsk during the last 8,000 years, with reference to the stages of the Baltic Sea, were reconstructed. Diatom analyses of two cores taken from the shallower and deeper parts of the basin enabled the conclusion to be drawn that the microflora studied developed in the three Baltic phases: Mastogloia, Littorina and Post-Littorina. Moreover, the so-called anthropogenic assemblage was observed in subbottom sediments of the study area.

Diatoms as indicators of eutrophication in the SW part of the Gulf of Gdańsk, the Baltic Sea

“…These species were noted as abundant in the previous studies on the Post-Littorina flora of the Gulf of Gdańsk (Witkowski 1994 The so-called 'anthropogenic assemblages' of diatoms were identified in the upper parts of cores R11, R12 and R13. The thickness of the zones varied from 14 cm in R12 and R13 to 23 cm in R11, which is comparable with the previous diatom analysis of bottom sediments of the study area (Witkowski 1994, Witkowski & Pempkowiak 1995, Stachura-Suchoples 1999, Leśniewska & Witak 2008, Witak 2010). Thickness differences between R11-II, R-12-II and R13-II DAZ may be explained by different sedimentation rates within the gulf.…”

“…It is known as a eutraphentic taxon tolerating α-mesosaprobic environment (van Dam et al 1994, Stachura-Suchoples 2001. In the study area it was observed by Witkowski (1994), Witkowski & Pempkowiak (1995), Stachura & Witkowski (1997), Stachura (1999), Witak (2000), , Leśniewska & Witak (2008) and Witak (2010). This species was recorded also in the Gulf of Finland (Weckström et al 2004, Clarke et al 2006) and the Gulf of Riga (Olli et al 2008) and the Szczecin Lagoon (Bąk et al 2001).…”

“…C. meneghiniana occurred rarely in the analyzed cores. Recorded commonly in sediments surrounding the Vistula River Mouth (Witkowski 1994, Witkowski & Pempkowiak 1995, Stachura & Witkowski 1997, Stachura-Suchoples 1999, this halophilous taxon proved to be an indicator of the influence by riverine waters (Leśniewska & Witak 2008). This diatom was also observed in samples from the Szczecin Lagoon (Andrén 1999, Bąk et al 2001, Bąk 2004, the Gulf of Finland (Weckström et al 2004, Clarke et al 2006 and the Roskilde Fjord (Clarke et al 2003(Clarke et al , 2006.…”

“…5 -20% in superficial sediments. It was frequent in diatom assemblages preserved in the superficial sediments of the Gulf of Gdańsk (Witkowski 1994, Witkowski & Pempkowiak 1995, Stachura & Witkowski 1997, Stachura-Suchoples 1999, Witak 2000, Leśniewska & Witak 2008, Witak 2010. It was encountered also in sediment samples from the Gotland Basin (Andrén et al 2000a), the Bornholm Basin , the Arkona Basin, Oder Rinne and Greisswalder Bodden , the Szczecin Lagoon (Bąk et al 2001(Bąk et al , 2006, the Archipelago Sea (Tuovinen et al 2009), the Gulf of Finland (Weckström et al 2004, Olli et al 2008, the Gulf of Riga, the Kattegat (Olli et al 2008) and the Roskilde Fjord sediments in Denmark (Clarke et al 2003(Clarke et al , 2006.…”

“…Progressive eutrophication of the gulf was so far evidenced in some of the cores from the study area by the presence of so-called 'anthropogenic assemblages' of diatoms, dominated by pollution resistant taxa, such as Cyclotella choctawhatcheeana Prasad, C. meneghiniana Kützing, Stephanodiscus hantzschii Grunow and Thalassiosira levanderi Van Goor (e.g. Witkowski 1994, Witkowski & Pempkowiak 1995, Stachura & Witkowski 1997, Stachura-Suchoples 1999, Stachura-Suchoples 2001, Leśniewska & Witak 2008, Witak 2010.…”