Tuomi, L., Kahma, K. K. & Pettersson, H. 2011: Wave hindcast statistics in the seasonally ice-covered Baltic Sea. Boreal Env. Res. 16: 451–472.
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Gottschalk, S. 2011: EU reference conditions in Swedish lakes identified with diatoms as palaeoindicators — a review. Boreal Env. Res. 16: 473–494.
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Kopáček, J., Turek, J., Hejzlar, J. & Porcal, P. 2011: Bulk deposition and throughfall fluxes of elements in the Bohemian Forest (central Europe) from 1998 to 2009. Boreal Env. Res. 16: 495–508.
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Setälä, O., Sopanen, S., Autio, R., Kankaanpää, H. & Erler, K. 2011: Dinoflagellate toxins in northern Baltic Sea phytoplankton and zooplankton assemblages. Boreal Env. Res. 16: 509–520.
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Rousi, H., Peltonen, H., Mattila, J., Bäck, S. & Bonsdorff, E. 2011: Impacts of physical environmental characteristics on the distribution of benthic fauna in the northern Baltic Sea. Boreal Env. Res. 16: 521–533.
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Tuomi, L., Kahma, K. K. & Pettersson, H. 2011: Wave hindcast statistics in the seasonally ice-covered Baltic Sea. Boreal Env. Res. 16: 451–472.

We used six years of wave hindcasts, calculated by the wave model WAM, to compile wave statistics for the Baltic Sea. The wave model was implemented taking into account the special features of the Baltic Sea: irregular coastline, archipelago and ice. To our knowledge, there is no single way to present annual statistics in seasonally ice-covered seas. We discuss five different possibilities to calculate the statistics, and the differences between them. According to verification against wave buoy and satellite altimeter measurements, the quality of the hindcast significant wave height is sufficient for presenting reliable wave statistics. The mean values of the significant wave height are smaller than 1.5 m. According to the mean values and exceedance probabilities, the severest wave climate is in the Baltic Proper. The wave climate in the other basins is considerably less severe. The maximum hindcast significant wave height is over 9 m, whereas the measured maximum is 8.2 m.

Gottschalk, S. 2011: EU reference conditions in Swedish lakes identified with diatoms as palaeoindicators — a review. Boreal Env. Res. 16: 473–494.

This study aims to assess the reference conditions and reference diatom communities for Swedish lakes by summarizing 36 performed palaeolimnological studies. The following results can serve as a tool in the discussion about reference conditions according to the European Water Framework Directive. (1) Finding one general fixed time of prevailing reference conditions for all Swedish lakes is impossible. (2) 1850 AD, as an often applied fixed reference time, is not an appropriate reference time for all Swedish lakes. (3) Reference nutrient and pH conditions for many southern Swedish lakes were prevailing until about 2300 BP. (4) Reference nutrient and pH conditions for many northern Swedish lakes prevailed longer and may even prevail today. (5) Different reference diatom communities can be found: either benthic (both acidophilous and alkaliphilous) or planktonic communities.

Kopáček, J., Turek, J., Hejzlar, J. & Porcal, P. 2011: Bulk deposition and throughfall fluxes of elements in the Bohemian Forest (central Europe) from 1998 to 2009. Boreal Env. Res. 16: 495–508.

We measured element concentrations and fluxes in bulk precipitation (at two sites) and throughfall (at four sites) in Norway spruce mountain stands in the Bohemian Forest (Czech Republic) from 1998–2009, with the aim to evaluate net atmospheric inputs of nutrients to the area, and (together with previous data from 1991–1997) long-term trends in acidic deposition. The average net atmospheric inputs of nutrients were 11, 4, 9, 62, 62, 45, 26, and 0.7–1.3 mmol m^–2 yr^–1 for Ca²⁺, Mg²⁺, K⁺, NO₃^–, NH₄⁺, total organic N, S, and total P (TP), respectively. The TP deposition was affected by a notable contribution from local dust and pollen sources. Throughfall pH increased from 3.6–3.7 in 1991–1994 to 4.7–5.0 in 2006–2009, due to average declines in the SO₄^2– plus NO₃^– concentrations by 202 µeq l^–1 and the H⁺ concentration by 147 µeq l^–1. The decline in throughfall concentrations of SO₄^2– (by 184 µeq l^–1) was the dominant driving force for the pH increase.

Setälä, O., Sopanen, S., Autio, R., Kankaanpää, H. & Erler, K. 2011: Dinoflagellate toxins in northern Baltic Sea phytoplankton and zooplankton assemblages. Boreal Env. Res. 16: 509–520.

The distribution of dinoflagellate toxins (OA, DTXs, PTXs, YTXs) in plankton communities was studied in the northern Baltic Sea during late summers of 2005 and 2006. The phycotoxins were analysed from samples that contained field collected microplankton in the size range of 20–76 ?m, zooplankton collected with a net, and individually hand-picked copepods from open-sea and coastal sampling stations. Concentrations of pectenotoxin-2 (PTX2) present in the microplankton samples containing Dinophysis spp. were between 2.1 and 10.6 pg cell^–1. Zooplankton net samples were positive for pectenotoxin seco acid (PTX2SA) at 10 sampling sites, and for PTX2 at two stations. The zooplankton net material contained also Dinophysis spp. cells that were the likely origin of these toxins, corresponding to 7.7–17.5 pg PTX2 cell^–1. Individually picked copepods did not contain any of the phycotoxins that were included in the analyses. Yessotoxin (YTX) was found in two microplankton samples. Toxins from the okadaic acid group were not detected. Our results confirm previous observations from the study area that the presence of PTX2 is a recurrent phenomenon in microplankton communities, whereas okadaic acid presence is not.

Rousi, H., Peltonen, H., Mattila, J., Bäck, S. & Bonsdorff, E. 2011: Impacts of physical environmental characteristics on the distribution of benthic fauna in the northern Baltic Sea. Boreal Env. Res. 16: 521–533.

The Baltic Sea is characterized by steep and strong environmental gradients in physical and chemical parameters which contribute to the geographic distribution of biota. At small scales, uneven bottom topography and heterogeneous sediment features induce high habitat diversity for example in the archipelago areas in the northern Baltic Sea. Here we analyse the impact/importance of sediment types and depth on the distribution of benthic animals in a relatively small (ca. 10 km²) archipelago area consisting of a mosaic of different benthic habitats interspaced with islands and skerries. A total of 26 major taxa of benthic macrofauna were found/observed in the study area. Results of the CCA analyses where depth and sediment types (clay, mud, sandy silt, fine sand, coarse sand, gravel and stones) were chosen as the environmental factors, revealed that habitat preferences of zoobenthic species were strongly affected by sediment types. Depth also impacted zonation of the species, but did not change the zonation patterns based on sediment characteristics. Macoma balthica, Saduria entomon and Harmothoe sarsi were identified as the only generalists while all other species/taxa showed clear correlation to different sediment types and depth zones. The animal-sediment patterns found reflected largely differential feeding modes of the species. The results clearly showed that sediment characteristics are of decisive importance for the composition of benthic fauna on soft bottoms.