The History of Eutrophication in the Sea Area of Helsinki in the 20th Century

Finni, Terttu; Laurila, Sari; Laakkonen, Simo

doi:10.1639/0044-7447(2001)030[0264:thoeit]2.0.co;2

Cited by 13 publications

(17 citation statements)

References 5 publications

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“…The historic phytoplankton data were counted from Lugol fixed samples under an inverted microscope after settling for 24 h (Edler 1979, HELCOM 1988. In the late 1960s and early 1970s, Keefe's solution (Keefe 1926) was used as fixative by the City of Helsinki Environment Centre (Finni et al 2001). Older samples (1975to 1992 provided by the Institute of Aquatic Sciences, University of Latvia, were formalin fixed and counted using a settling method (for details see Jurgensone et al 2011).…”

Section: Data Compilation Proceduresmentioning

confidence: 99%

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Harmonizing large data sets reveals novel patterns in the Baltic Sea phytoplankton community structure

Olli¹,

Trikk²,

Klais³

et al. 2013

Mar. Ecol. Prog. Ser.

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Phytoplankton forms the basis of aquatic food webs, and shifts in community composition reflect changes in environmental conditions. Despite the accepted importance, the processes behind maintaining spatial and temporal community structure and biodiversity at the base of the aquatic food web remain poorly described and understood. A recognized challenge hampering validation of ecological models and meta-analysis is the scarcity of large phytoplankton data sets. Compared to other aquatic data, harmonization of quantitative phytoplankton data sets from different sources and academic institutions has remained a major challenge. Here we demonstrate and examine processes used to compile and harmonize a large multi-sourced phytoplankton data set covering 40 yr of monitoring and over 15 000 quantitative samples from the Baltic Sea. We show differences in the quality of data among countries and analyze autocorrelation scales in field data. Phytoplankton community composition showed positive autocorrelation at a temporal scale of less than 30 d and had a recurrent pattern at a yearly interval. Both total biomass and community composition showed a positive spatial autocorrelation, but the extent of the data determines the autocorrelation scale and strength. We introduce a new strategy to select the best performing model to assess regional taxon richness in phytoplankton field data. The Weibull 4-parameter model showed both the best fit with data and robust parameter estimates at varying sample size.

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Section: Data Compilation Proceduresmentioning

confidence: 99%

“…Notes on phytoplankton abundance and even algal blooms in the Baltic Sea date back to the mid 19th century (Eichwald 1847, Olli 1996, Finni et al 2001. Data sets with species abundances and biomasses, taken and processed with modern methods, are available since the mid-1960s (Wasmund et al 2008, Jurgensone et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Harmonizing large data sets reveals novel patterns in the Baltic Sea phytoplankton community structure

Olli¹,

Trikk²,

Klais³

et al. 2013

Mar. Ecol. Prog. Ser.

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“…The load into Laajalahti Bay in the mid-1800s was estimated to be 1.5 and 17 t TN yr -1 based on the development of the average daily per capita nutrient load and the approximate population, which was assumed to have developed in parallel with the population in the catchment area of Helsinki (see Laakkonen & Peltonen 1999); there was no general sewage network at that time. However, pollution of coastal waters in Helsinki must have already started in the late 1880s on the basis of first-hand accounts at that time (Laakkonen 2001).…”

Section: Natural Conditionsmentioning

confidence: 99%

“…This period was characterised by a slow rise in the population and a lack of treatment of wastewaters (Laakkonen & Peltonen 1999). Most of the lavatory sewage in Helsinki at the time was discharged to coastal waters, because nearly 2 out of 3 apartments had flushing toilets (Laakkonen 2001). Wastewaterloading spread to a wider area, as the network of wastewater pipelines extended to the western part of Helsinki.…”

Section: Onset Of Anthropogenic Impactmentioning

confidence: 99%

“…However, increases in sedimentary pigments arise through better preservation (Leavitt 1993). Bluegreen algal blooms appear to have been a common phenomenon in the receiving waters near large cities such as Helsinki before the introduction of sewage treatment (Finni et al 2001). The N 2 -fixing cyanobacteria Aphanizomenon spp.…”

Section: Onset Of Anthropogenic Impactmentioning

confidence: 99%

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Tracing pollution and recovery using sediments in an urban estuary, northern Baltic Sea: are we far from ecological reference conditions?

Kauppila¹,

Weckström²,

Vaalgamaa³

et al. 2005

Mar. Ecol. Prog. Ser.

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One of the primary challenges of the Water Framework Directive (WFD) of the European Union is to provide a guide for the recovery of surface waters from pollution. However, few studies deal with reference conditions according to the WFD in coastal waters. Using the urbanised Laajalahti Bay (Helsinki, Finland) as an example, reference conditions and pollution history were defined using the stratigraphy of diatoms, sediment geochemistry, stable isotopes, sedimentary pigments, long-term monitoring results of water quality, and nutrient-loading. Principal components analysis was used to generate a multidimensional index of water quality on the basis of the sediment data. We distinguished 5 phases: (1) a pre-industrial phase (before ca. 1815); (2) a phase of slight human disturbance (ca. 1815 to 1900); (3) an onset of anthropogenic impact (ca. 1900 to 1955); (4) a severe pollution phase (ca. 1955 to 1975); (5) basin recovery and a phase of internal loading (from ca. 1975 onwards). Phase 2 was used to define reference conditions. Phase 1 was not used as it occurred before the formation of the semi-enclosed bay by post-glacial isostatic land-uplift. There was good agreement between the sedimentary record and the water-quality data during Phase 4. Despite an improvement in water quality after the local municipal treatment plant closed in 1986, Laajalahti Bay is still far from reference conditions due to internal loading.

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Interaction between the land and the sea: sources and patterns of nutrients in the scattered coastal zone of a eutrophied sea

Raateoja

Kauppila

2018

Environ Monit Assess

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A long-term trophic development of three geographical transects—including a river mouth, an estuary, and an archipelago—were studied in the southern Finnish coast in the Baltic Sea. Each transect was studied to clarify how far off the coast the land-based nutrient sources (catchment factor, CF) had a decisive role in shaping the wintertime regimes of dissolved inorganic nitrogen and dissolved inorganic phosphorus and where the marine processes (marine factor, MF) start to play a major role. Generally, CF controlled the nutrient regime from the coast to the outer brink of the inner coastal area, after which MF started to dominate. The estuaries exhibited steep vertical nutrient gradients, above which the riverine input dominated the nutrient regime. The extent of the area where CF dominated the nutrient regime was therefore decisively dependent on estuarine stratification, i.e., whether the conclusions were drawn based on the surface layer data, including the riverine impact, or on the data beneath that layer, including the marine impact. This result deviates from the current consensus that the trophic regime of the sea is most directly assessed by the surface layer nutrient content. The estuarine nutrient regime is unrepresentative to that of a typical coastal water body due to the strong land-based impact on the estuary. Therefore, any generalization of the trophic condition of an estuary to represent areas farther off the coast should be done cautiously. The estuaries should also be defined as belonging to transitional waters according to the typology related to European Marine Legislation.

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The History of Eutrophication in the Sea Area of Helsinki in the 20th Century

Cited by 13 publications

References 5 publications

Harmonizing large data sets reveals novel patterns in the Baltic Sea phytoplankton community structure

Harmonizing large data sets reveals novel patterns in the Baltic Sea phytoplankton community structure

Tracing pollution and recovery using sediments in an urban estuary, northern Baltic Sea: are we far from ecological reference conditions?

Interaction between the land and the sea: sources and patterns of nutrients in the scattered coastal zone of a eutrophied sea

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