Gulf of Riga and Pärnu Bay

Kotta, Jonne; Lauringson, Velda; Martin, Georg; Simm, Mart; Kotta, Ilmar; Herkül, Kristjan; Ojaveer, Henn

doi:10.1007/978-3-540-73524-3_10

Cited by 72 publications

(90 citation statements)

References 51 publications

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“…The oxygen regime is relatively good due to strong vertical mixing. In most areas, oxygen concentrations are higher than 5 ml l -1 [13]. In consequence of limited water exchange, the Gulf is more eutrophicated than the Baltic Proper, and the outflow of nutrients through the straits is higher than the inflow [14,15].…”

Section: Methodsmentioning

confidence: 99%

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Bayesian inference for predicting ecological water quality under different climate change scenarios

Kotta

Aps

Orav‐Kotta

2009

WIT Transactions on Ecology and the Environment

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The aim of this paper is to assess the separate and interactive effects of eutrophication and climate variables on the sea water quality in Pärnu Bay (the Gulf of Riga, Baltic Sea) using multivariate statistical analyses and the Bayesian Belief Network (BBN) methodology. The assessment was based on the following biological quality elements: phytoplankton, submerged aquatic vegetation and benthic invertebrates. The multivariate statistical analyses suggest that zoobenthos communities are largely driven by weather conditions (i.e. climate variables), phytoplankton by nutrient loads while the dynamics of macrophyte communities was due to the combined effect of weather and nutrient loads. The BBN constructed for this study represents uncertainty in ecological water quality assessment. Probabilistic modeling shows that phytoplankton and zoobenthos are not sensitive to climate change impacts while phytobenthos would suffer from decrease in sea water salinity. Under climate change, therefore, phytobenthos is one of the key variables in determining the water quality in the study area.

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Section: Methodsmentioning

confidence: 99%

“…In summer and early autumn, the concentrations remain low. After November, a gradual increase takes place due to the higher intensity of vertical mixing [13].…”

Section: Methodsmentioning

confidence: 99%

Bayesian inference for predicting ecological water quality under different climate change scenarios

Kotta

Aps

Orav‐Kotta

2009

WIT Transactions on Ecology and the Environment

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“…In most years, the bay is fully ice-covered during winter, usually from December/ January to March/April. Sea surface temperature (SST) fluctuates seasonally from regularly sub-zero degrees °C in winter to >20 °C in summer; salinity varies between three and six PSU (Practical Salinity Unit) and water is typically well mixed down to the bottom year around [23]. The currents are weak (velocities of <10 cm s ) and mainly wind-induced, but modified by coastline morphology and bottom topography.…”

Section: Study Sitementioning

confidence: 99%

Maturation at a young age and small size of European smelt (Osmerus eperlanus): A consequence of population overexploitation or climate change?

et al. 2017

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Age of fish at maturation depends on the species and environmental factors but, in general, investment in growth is prioritized until the first sexual maturity, after which a considerable and increasing proportion of resources are used for reproduction. The present study summarizes for the first the key elements of the maturation of European smelt (Osmerus eperlanus) young of the year (YoY) in the North-eastern Gulf of Riga (the Baltic Sea). Prior to the changes in climatic conditions and collapse of smelt fishery in the 1990s in the Gulf of Riga, smelt attained sexual maturity at the age of 3-4 years. We found a substantial share (22%) of YoY smelt with maturing gonads after the collapse of the smelt fisheries. Maturing individuals had a significantly higher weight, length and condition factor than immature YOY, indicating the importance of individual growth rates in the maturation process. The proportion of maturing YoY individuals increased with fish size. We discuss the factors behind prioritizing reproduction overgrowth in early life and its implications for the smelt population dynamics.

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“…1) for many decades. The mesotrophic Gulf is one of the most nutrient polluted sub-basins of the Baltic Sea (Håkanson and Bryhn 2008a;Kotta et al 2008). Urban sewage treatment is the most effective, and also a comparatively cost-effective way to decrease the total phosphorus (TP) loading to the Gulf of Riga (Bryhn, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…1) has a surface area of 16 700 km 2 , a mean depth of 24.5 m and a maximum depth of 56 m (Håkanson and Bryhn 2008a). The water of the Gulf is brackish as the salinity in most parts ranges from 5.5 to 6.0 psu (Kotta et al 2008 Pärnu (Estonia/Latvia), and River Salaca/Salatsi (Latvia/Estonia).…”

Section: Introductionmentioning

confidence: 99%

Estimated Trophic State Effects and Abatement Costs in Connection with Improved Urban Sewage Treatment in the Gulf of Riga

Bryhn

2012

J. Environ. Eng.

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Environmental conflicts of interest are important to account for when environmental policies are designed. This paper explores the quantitative connection between urban waste water treatment, coastal eutrophication, and fish biomass in the mesotrophic Gulf of Riga (northern Europe). The probable effect on the water quality from one clearly defined abatement measure, improved urban sewage treatment has been studied. Furthermore, the implementation cost and the likely effect on total fish biomass have also been assessed. Computer simulations using the previously published model CoastMab suggested that good water quality according to the EU Marine Strategy Framework Directive could be achieved if urban sewage treatment would be upgraded to Nordic and German standards, and not only around the Gulf of Riga but in the whole Baltic Sea drainage basin. The Secchi depth would double according to these simulations while total phosphorus and summer chlorophyll concentrations would decrease by 54% and 53%, respectively. The total fish biomass should be expected to decrease by about 42% if "good" water quality (as defined in European Union directives) should be achieved. However, changes in total fish biomass could also be offset by changes in other important determinants such as climate related variables or fishing pressure. The study estimated that it could take about 20-40 years after abatement action for the trophic state in the Gulf to stabilise again. Upgrading urban sewage treatment to this extent would cost 468-1,118 million euros per year. Treatment could have substantial positive effects on the water quality of the Gulf but could also have adverse side effects on the total fish biomass.

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Gulf of Riga and Pärnu Bay

Cited by 72 publications

References 51 publications

Bayesian inference for predicting ecological water quality under different climate change scenarios

Bayesian inference for predicting ecological water quality under different climate change scenarios

Maturation at a young age and small size of European smelt (Osmerus eperlanus): A consequence of population overexploitation or climate change?

Estimated Trophic State Effects and Abatement Costs in Connection with Improved Urban Sewage Treatment in the Gulf of Riga

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