Juvenile flatfish in the northern Baltic Sea — long-term decline and potential links to habitat characteristics

The long-term fate of chlorophenols and adsorbable organic halogens (AOX) was studied in two large recipients of bleach-plant effluents: Lake Vättern in Sweden and the Baltic Sea. The study showed that there is a long-distance transport (>100 km) of chloroguaiacols from bleach-plants to remote parts of receiving waters. However, there was no evidence of several-year-long accumulation of chloro-organics in the water-phase. A simple water-exchange model for Lake Vättern showed that the cumulated bleach-plant discharges from the past 35 years would have increased the AOX concentration in the lake by more than 100 µg Cl/l, if no AOX had been removed from the water by evaporation, sedimentation or degradation. However, the observed AOX concentration in Lake Vättern averaged only about 15 µg Cl/l, which was less than the average AOX concentration (32 µg Cl/l) in the “unpolluted” tributaries of the lake. Similar investigations in the Baltic Sea showed that non-point sources, including natural halogenation processes, accounted for a substantial fraction of the AOX in the open sea. The presence of 2,4,6-trichlorophenol in precipitation and “unpolluted” surface waters showed that non-point sources may also make a considerable contribution to the background levels of compounds normally regarded as indicators of bleach-plant effluents.

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Long term couplings of winter index of North Atlantic oscillation and water level in the Baltic Sea and Kattegat

Ocean Engineering ◽

10.1016/j.oceaneng.2015.09.014 ◽

2015 ◽

Vol 109 ◽

pp. 113-126

Author(s):

Grzegorz Różyński

Keyword(s):

Baltic Sea ◽

North Atlantic Oscillation ◽

Water Level ◽

North Atlantic ◽

The Baltic Sea ◽

The Baltic

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Long-term spatial variations in the Baltic Sea wave fields

Ocean Science ◽

10.5194/os-7-141-2011 ◽

2011 ◽

Vol 7 (1) ◽

pp. 141-150 ◽

Cited By ~ 23

Author(s):

T. Soomere ◽

A. Räämet

Keyword(s):

Baltic Sea ◽

Spatial Variations ◽

Extreme Wave ◽

The Baltic Sea ◽

Wave Fields ◽

Wave Heights ◽

The Baltic ◽

Wave Properties ◽

Sea Wave

Abstract. This study focuses on spatial patterns in linear trends of numerically reconstructed basic wave properties (average and extreme wave heights, wave periods) in the Baltic Sea under the assumption of no ice cover. Numerical simulations of wave conditions for 1970–2007, using the WAM wave model and adjusted geostrophic winds, revealed extensive spatial variations in long-term changes in both average and extreme wave heights in the Baltic Sea but almost no changes in the basinwide wave activity and wave periods. There has been a statistically significant decrease in the annual mean significant wave height by more than 10% between the islands of Öland and Gotland and in the southward sea area, and a substantial increase to the south-west of Bornholm, near the coast of Latvia, between the Åland Archipelago and the Swedish mainland, and between the Bothnian Sea and the Bothnian Bay. Variations in extreme wave heights (defined as the threshold for 1% of the highest waves each year) show similar patterns of changes. In several areas the trends in average and extreme wave heights are different. Such a complicated pattern of changes indicates that (i) different regions of the Baltic Sea basin have experienced widespread but essentially different changes in wind properties and (ii) many seemingly controversial trends and variations established in wave properties at different sites in the recent past may reflect the natural spatial variability in the Baltic Sea wave fields.

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Supplementary material to "Long-term coastal openness variation and its impact on sediment grain-size distribution: a case study from the Baltic Sea"

10.5194/esurf-2016-24-supplement ◽

2016 ◽

Author(s):

Wenxin Ning ◽

Jing Tang ◽

Helena L. Filipsson

Keyword(s):

Grain Size ◽

Baltic Sea ◽

Size Distribution ◽

Grain Size Distribution ◽

The Baltic Sea ◽

Sediment Grain Size ◽

Supplementary Material ◽

The Baltic

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A century of genetic homogenization in Baltic salmon—evidence from archival DNA

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.3147 ◽

2021 ◽

Vol 288 (1949) ◽

Author(s):

Johan Östergren ◽

Stefan Palm ◽

John Gilbey ◽

Göran Spong ◽

Johan Dannewitz ◽

...

Keyword(s):

Baltic Sea ◽

Large Scale ◽

Isolation By Distance ◽

Anthropogenic Impacts ◽

Genetic Change ◽

Past Century ◽

The Baltic Sea ◽

The Baltic ◽

Archival Dna

Intra-species genetic homogenization arising from anthropogenic impacts is a major threat to biodiversity. However, few taxa have sufficient historical material to systematically quantify long-term genetic changes. Using archival DNA collected over approximately 100 years, we assessed spatio-temporal genetic change in Atlantic salmon populations across the Baltic Sea, an area heavily impacted by hydropower exploitation and associated with large-scale mitigation stocking. Analysis was carried out by screening 82 SNPs in 1680 individuals from 13 Swedish rivers. We found an overall decrease in genetic divergence and diminished isolation by distance among populations, strongly indicating genetic homogenization over the past century. We further observed an increase in genetic diversity within populations consistent with increased gene flow. The temporal genetic change was lower in larger wild populations than in smaller wild and hatchery-reared ones, indicating that larger populations have been able to support a high number of native spawners in relation to immigrants. Our results demonstrate that stocking practices of salmon in the Baltic Sea have led to the homogenization of populations over the last century, potentially compromising their ability to adapt to environmental change. Stocking of reared fish is common worldwide, and our study is a cautionary example of the potentially long-term negative effects of such activities.

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