Coastal eutrophication: Causes, consequences and perspectives in the Archipelago areas of the northern Baltic Sea

Bonsdorff, Erik; Blomqvist, Ea Maria; Mattila, Johanna; Norkko, Alf

doi:10.1016/s0272-7714(97)80008-x

Cited by 226 publications

(131 citation statements)

References 29 publications

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“…These tolerances make Ulva the most common macroalgal genus in marine littoral habitats. Massive blooms of a single species or aggregates of several species are often encountered in the form of mats that float freely on the water surface in spring and summer (Bonsdorff et al, 1997;Alström-Rapaport et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Ulva flexuosa(Ulvaceae, Chlorophyta) inhabiting inland aquatic ecosystems: molecular, morphological and ecological discrimination of subspecies

Rybak

Czerwoniec²,

Gąbka

et al. 2014

European Journal of Phycology

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Species of Ulva (Ulvaceae, Chlorophyta) are relatively common macroalgae in most coastal areas. In this paper, we examine Ulva in inland aquatic ecosystems to determine relationships between the chemical parameters of the water and the Ulva taxa present. Two groups of samples of freshwater Ulva were selected from: (i) habitats with high salinity levels, and (ii) habitats with fresh or slightly saline waters. We showed that these two groups of Ulva, which occupy distinct habitats, represent two separate taxa. The first group represents Ulva flexuosa subsp. pilifera (Kützing) M.J. Wynne, which is very common and regularly encountered in fresh waters, but is equally well represented in slightly saline waters. The second is U. flexuosa subsp. paradoxa (C. Agardh) M.J. Wynne, which is less common, preferring mainly salt-wedge saline waters. We did not find both Ulva flexuosa subspecies together at any of the research sites.There were significant morphological differences between the Ulva flexuosa subspecies. Ulva flexuosa subsp. pilifera had longer and wider thalli and wider cells than those of subsp. paradoxa. Ulva flexuosa subsp. paradoxa cells were longer and of greater circumference than those of subsp. pilifera. Analyses of the rRNA ITS region and partial rbcL gene sequences demonstrated minor sequence variation within the two subspecies. The results of this study provide detailed information on the characteristics of limnic Ulva habitats and indicate the niches where such populations are likely to occur.

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Section: Introductionmentioning

confidence: 99%

Ulva flexuosa(Ulvaceae, Chlorophyta) inhabiting inland aquatic ecosystems: molecular, morphological and ecological discrimination of subspecies

Rybak

Czerwoniec²,

Gąbka

et al. 2014

European Journal of Phycology

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“…However, the prominent aggravation of hypoxia in the 1950s was unequivocally anthropogenically-induced. The timing of this shift predates the major establishment period of fish farms in the Archipelago Sea in 1970s (Hänninen et al, 2000), suggesting that although aquaculture has aggravated hypoxia since the 1970s (Bonsdorff et al, 1997a), other human activities 10 had significantly degraded the coastal water quality up to 20 years previously.…”

Section: Discussionmentioning

confidence: 99%

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

Jokinen¹,

Virtasalo²,

Jilbert³

et al. 2018

Preprint

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Abstract. The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment.Here 5 we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented, and besides gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. The 10 progressive deoxygenation since the beginning of 1900s was originally triggered by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the anthropogenic eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s through fueling primary productivity, while we find no evidence of anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal 15 water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality. 25Biogeosciences Discuss., https://doi

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“…It has been estimated that the sedimentation of organic matter and thus the burial of C, N and P increased in the Baltic Sea during the latter half of the twentieth century as a result of eutrophication (Jonsson and Carman 1994;Bonsdorff et al 1997;Emeis et al 2000;Vaalgamaa and Conley 2008). Jonsson and Carman (1994) suggested an increase in organic matter deposition by a factor larger than 1.7 between the 1920s and 1980s in the northern Baltic Proper and Emeis et al (2000) estimated a fourfold increase in sediment accumulation in the Bornholm, Gdansk and Gotland basins since 1900.…”

Section: Past Changesmentioning

confidence: 99%

Environmental Impacts—Marine Biogeochemistry

Schneider

Eilola

Lukkari

et al. 2015

Regional Climate Studies

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Marine biogeochemistry deals with the budgets and transformations of biogeochemically reactive elements such as carbon, nitrogen and phosphorus. Inorganic nitrogen and phosphorus compounds are the major nutrients and control organic matter (biomass) production in the surface water. Due to various anthropogenic activities, the input of these nutrients into the Baltic Sea has increased drastically during the last century and has enhanced the net organic matter production by a factor of 2-4 (eutrophication). This has led to detrimental oxygen depletion and hydrogen sulphide production in the deep basins of the Baltic Sea. Model simulations based on the Baltic Sea Action Plan (BSAP) indicate that current eutrophication and thus extension of oxygen-depleted areas cannot be reversed within the next hundred years by the proposed nutrient reduction measures. Another environmental problem is related to decreasing pH (acidification) that is caused by dissolution of the rising atmospheric CO 2 . Estimates indicate a decrease in pH by about 0.15 during the last 1-2 centuries, and continuation of this trend may have serious ecological consequences. However, the concurrent increase in the alkalinity of the Baltic Sea may have significantly counteracted acidification.

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Coastal eutrophication: Causes, consequences and perspectives in the Archipelago areas of the northern Baltic Sea

Cited by 226 publications

References 29 publications

Ulva flexuosa(Ulvaceae, Chlorophyta) inhabiting inland aquatic ecosystems: molecular, morphological and ecological discrimination of subspecies

Ulva flexuosa(Ulvaceae, Chlorophyta) inhabiting inland aquatic ecosystems: molecular, morphological and ecological discrimination of subspecies

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

Environmental Impacts—Marine Biogeochemistry

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Coastal eutrophication: Causes, consequences and perspectives in the Archipelago areas of the northern Baltic Sea

Cited by 226 publications

References 29 publications

Ulva flexuosa(Ulvaceae, Chlorophyta) inhabiting inland aquatic ecosystems: molecular, morphological and ecological discrimination of subspecies

Ulva flexuosa(Ulvaceae, Chlorophyta) inhabiting inland aquatic ecosystems: molecular, morphological and ecological discrimination of subspecies

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20&lt;sup&gt;th&lt;/sup&gt; century

Environmental Impacts—Marine Biogeochemistry

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A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century