Gulf of Finland Research Papers (original) (raw)

With improved observation methods, increased winter navigation, and increased awareness of the climate and environmental changes, research on the Baltic Sea ice conditions has become increasingly active. Sea ice has been recognized as a sensitive indicator for changes in climate. Although the interannual variability in the ice conditions is large, a change towards milder ice winters has been detected from the time series of the maximum annual extent of sea ice and the length of the ice season. On the basis of the ice extent, the shift towards a warmer climate took place in the latter half of the 19th century. On the other hand, data on the ice thickness, which are mostly limited to the land-fast ice zone, basically do not show clear trends during the 20th century, except that during the last 20 years the thickness of land-fast ice has decreased. Due to difficulties in measuring the pack-ice thickness, the total mass of sea ice in the Baltic Sea is, however, still poorly known. The ice extent and length of the ice season depend on the indices of the Arctic Oscillation and North Atlantic Oscillation. Sea ice dynamics, thermodynamics, structure, and properties strongly interact with each other, as well as with the atmosphere and the sea. The surface conditions over the ice-covered Baltic Sea show high spatial variability, which cannot be described by two surface types (such as ice and open water) only. The variability is strongly reflected to the radiative and turbulent surface fluxes. The Baltic Sea has served as a testbed for several developments in the theory of sea ice dynamics. Experiences with advanced models have increased our understanding on sea ice dynamics, which depends on the ice thickness distribution, and in turn redistributes the ice thickness. During the latest decade, advance has been made in studies on sea ice structure, surface albedo, penetration of solar radiation, sub-surface melting, and formation of superimposed ice and snow ice. A high vertical resolution has been found as a prerequisite to successfully model thermodynamic processes during the spring melt period. A few observations have demonstrated how the river discharge and ice melt affect the stratification of the oceanic boundary layer below the ice and the oceanic heat flux to the ice bottom. In general, process studies on ice-ocean interaction have been rare. In the future, increasingly multidisciplinary studies are needed with close links between sea ice physics, geochemistry and biology.

- by
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- Geology, Oceanography, Thermodynamics, Time Series

Continuous measurements of the surface water CO 2 partial pressure (pCO 2) and the chlorophyll a fluorescence were performed in the Baltic Sea using a fully automated measurement system deployed on a cargo ship. The ship commuted regularly at two day intervals between the Mecklenburg Bight (Luebeck) and the Gulf of Finland (Helsinki). The pCO 2 data collected during June 2003 and September 2004 were used to identify biological production events such as the spring bloom and the midsummer cyanobacteria bloom in five different sub-regions. To quantify the net biomass production, the decrease of the total CO 2 , N C T (normalized to a uniform alkalinity), during the production periods was calculated using the pCO 2 , temperature and salinity records and the mean alkalinity. Taking into account the CO 2 air/sea exchange and the formation of dissolved organic carbon, a simple mass balance yielded the net production of particulate organic carbon which represents the total biomass. The chlorophyll a concentrations obtained from the fluorescence data showed peaks that in most cases coincided with the production maxima and thus supported the interpretation of the pCO 2 data. The production during both the spring bloom (2004) and the midsummer nitrogen fixation period (2003) increased by a factor of about three from the southwest to the northeast. For the spring bloom our estimates were significantly higher than those based on the winter nutrient supply and Redfield C / N and C / P ratios. This indicated the existence of additional nutrient sources such as dissolved organic nitrogen, early nitrogen fixation and preferential P mineralization. Midsummer N C T minima were observed only in 2003 and used to quantify the nitrogen fixation activity and to characterize its interannual variability.

- by Seppo Kaitala
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- Oceanography, Carbon Dioxide, Nitrogen Fixation, Surface Water

Maritime traffic poses various risks in terms of human, environmental and economic loss. In a risk analysis of ship collisions, it is important to get a reasonable estimate for the probability of such accidents and the consequences they lead to. In this paper, a method is proposed to assess the probability of vessels colliding with each other. The method is capable of determining the expected number of accidents, the locations where and the time when they are most likely to occur, while providing input for models concerned with the expected consequences. At the basis of the collision detection algorithm lays an extensive time domain micro-simulation of vessel traffic in the given area. The Monte Carlo simulation technique is applied to obtain a meaningful prediction of the relevant factors of the collision events. Data obtained through the Automatic Identification System is analyzed in detail to obtain realistic input data for the traffic simulation: traffic routes, the number of vessels on each route, the ship departure times, main dimensions and sailing speed. The results obtained by the proposed method for the studied case of the Gulf of Finland are presented, showing reasonable agreement with registered accident and near-miss data.

- by Pentti Kujala
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- Engineering, Traffic Simulation, Monte Carlo Simulation, Risk Analysis

Among engineers, risk is defined as a product of probability of the occurrence of an undesired event and the expected consequences in terms of human, economic, and environmental loss. These two components are equally important; therefore, the appropriate estimation of these values is a matter of great significance. This paper deals with one of these two components-the assessment of the probability of vessels colliding, presenting a new approach for the geometrical probability of collision estimation on the basis of maritime and aviation experience. The geometrical model that is being introduced in this paper takes into account registered vessel traffic data and generalised vessel dynamics and uses advanced statistical and optimisation methods (Monte Carlo and genetic algorithms). The results obtained from the model are compared with registered data for maritime traffic in the Gulf of Finland and a good agreement is found. (J. Montewka).

- by Jakub Montewka and +1
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- Engineering, Risk, Shipping, Reliability Engineering

HEINSALU, ATKO, VESKI, SIIM and VASSILJEV, JÜRI 2000. Palaeoenvi- ronment and shoreline displacement on Suursaari Island, the Gulf of Finland. Bulletin of the Geological Society of Finland 72, Parts 1-2, 21-46. The island of Suursaari in the middle of the Gulf of Finland is exceptionally high (175 m a.s.l.). Sediment profiles from one mire and three lakes were in- vestigated

- by Atko Heinsalu
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- Brackish Water, Radiocarbon Dating, Late Glacial, Vegetation history

The paper presents a model for risk analysis regarding marine traffic, with the emphasis on two types of the most common marine accidents which are: collision and grounding. The focus is on oil tankers as these pose the highest environmental risk. A case study in selected areas of Gulf of Finland in ice free conditions is presented. The model utilizes a well-founded formula for risk calculation, which combines the probability of an unwanted event with its consequences. Thus the model is regarded a block type model, consisting of blocks for the probability of collision and grounding estimation respectively as well as blocks for consequences of an accident modelling. Probability of vessel colliding is assessed by means of a Minimum Distance To Collision (MDTC) based model. The model defines in a novel way the collision zone, using mathematical ship motion model and recognizes traffic flow as a non homogeneous process. The presented calculations address waterways crossing between Helsinki and Tallinn, where dense cross traffic during certain hours is observed. For assessment of a grounding probability, a new approach is proposed, which utilizes a newly developed model, where spatial interactions between objects in different locations are recognized. A ship at a seaway and navigational obstructions may be perceived as interacting objects and their repulsion may be modelled by a sort of deterministic formulation. Risk due to tankers running aground addresses an approach fairway to an oil terminal in Sköldvik, near Helsinki. The consequences of an accident are expressed in monetary terms, and concern costs of an oil spill, based on statistics of compensations claimed from the International Oil Pollution Compensation Funds (IOPC Funds) by parties involved.

- by P. Krata and +1
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- Risk, Safety, COLLISION, Maritime traffic

Монография является итоговой работой, объединившей исследования последних десятилетий отечественных
и зарубежных специалистов по восстановлению миграционных и культурных процессов восточной части Балтий-
ского региона в VI–III тыс. до н.э., а также по моделированию палеогеографической ситуации Нарвско-Лужского
междуречья. Исследование представляет данные для реконструкции древних культурных и природных процессов
в голоцене далеко за пределами рассматриваемой территории. Издание предназначено для специалистов по архео-
логии и палеогеографии, смежным специальностям, краеведов и всех интересующихся древней историей человека
и природы Прибалтийского региона.

- by Dmitriy Gerasimov and +9
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- Coastal Geomorphology, Neolithic Archaeology, Gulf of Finland

Eutrophication of the Baltic Sea has become a serious concern in recent decades. To provide a potential means for quality assessments of coastal waters in this area, we collected a data set of 49 embayments in the Gulf of Finland, and explored the relationship between surface sediment diatom assemblages and 15 environmental variables, with special emphasis on nutrients. Total dissolved nitrogen, total phosphorus, depth, and salinity all accounted for significant and independent fractions of variation in the diatom data and explained 34% of the total variation. There were clear changes in diatom assemblage structures along the nutrient gradients. Although these changes were gradual, we could identify a number of taxa that were more abundant in a particular nutrient environment. These taxa could be used as potential indicators of the quality of coastal waters in the Baltic Sea. Diatom assemblages that were least affected by nutrient enrichment included a variety of benthic species and a relatively high species richness. Small planktonic taxa such as Cyclotella atomus Hustedt, Cyclotella meneghiniana Kützing and Thalassiosira pseudonana Hasle and Heimdal were good indicators of highly elevated nutrient concentrations (4600 lg . L À 1 total dissolved nitrogen and 60 lg . L À 1 total phosphorus) together with low species richness. The first appearance of these small planktonic taxa in regular monitoring could be used as an early warning sign for deteriorating water quality. Diatoms could be applied to water quality classification and monitoring purposes in the coastal waters of the Baltic Sea area using techniques such as weighted-averaging regression and calibration.

- by Stephen Juggins
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- Phycology, Plant Biology, Eutrophication, Biomonitoring

The eVect of temperature on the development and hatching of resting eggs of the Ponto-Caspian Cercopagis pengoi was studied experimentally in the Gulf of Finland, Baltic Sea. Morphological changes were monitored as the development of the resting eggs proceeded. Sexual reproduction of the C. pengoi population in the Gulf of Finland was evaluated by combining the data from hatching experiments and resting egg abundances in the sediment. Development time of resting eggs was dependent on temperature: increase in the temperature shortened the time needed until hatching. Hatching success was also dependent on incubation temperature. Almost sixfold increase in hatching success was detected when temperature increased two degrees above the storage temperature. Average resting egg abundances varied between 0.16 and 0.49 eggs cm ¡3 in the 0-6 cm sediment layer.

- by S. Sopanen
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- Marine Biology, Biological Sciences, Environmental Sciences, Gulf of Finland

Summary We discuss the relationship of EVRS2000 and EVRF2000 to future national height systems in Europe and specifically in Finland, Norway, and Sweden. The EVRF2000 in these countries is based on their second precise levellings and the... more

- by Jaakko Mäkinen
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- Nordic countries, Gulf of Finland

The maritime traffic is increasing constantly, in terms of number and size of ships. This, on one hand meets the growing demands of the society but on another pose certain risks, both on the environment and the aforementioned society. Therefore a holistic approach is required in order to estimate these dynamic risks and keep them under control. As the risk is perceived as a combination of the probability of an accident and its consequences a proper estimation of these two is of high importance. Therefore this paper introduces a novel approach for estimating the consequences of an open sea collision between two ships, with the attention on a RoPax ship being considered a struck ship. Presented model utilizes the Bayesian network and takes into account composition of maritime traffic in the analysed sea area, ship hydrodynamics, stability, crash-worthiness and collision dynamics. Moreover the accident response is considered with respect to the locations of salvage and rescue ships, evacuation time as well as weather conditions and time of the day at which an accident is probable to happen.

- by Floris Goerlandt
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- Bayesian Networks, Risk Analysis, Ropax, Gulf of Finland

The concentrations and congeners pattern of the polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were determined in sprat collected by the commercial catches in the Gulf of Finland, Baltic Sea. Based on the toxic equivalent concentrations 2,3,4,7,8-PeCDF prevailed among the congeners of PCDD/Fs. The significance of age-and season-specific relationship between the concentration of lipids and dioxins was demonstrated. On lipid weight basis the concentration of PCDDs was significantly higher in spring than in autumn. This difference was not statistically significant for PCDFs. On lipid weight basis the concentration of dioxins decreased with rising content of lipids. PCDD/Fs toxic equivalent concentration increased with the age of sprat exceeding the EU maximum limit value at more than 5-year-old fish.

- by Jonne Kotta and +2
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- Multidisciplinary, Lipids, Seasonality, Fishes

Background, aim, and scope The paper describes the spatial contamination of the River Kymijoki, South-Eastern Finland, and the coastal region of the Gulf of Finland with PCDD/Fs and mercury. The findings of ecotoxicologial and human health studies are also reported, including environmental and human risk assessments. Sediments from the River Kymijoki, draining into the Gulf of Finland, have been heavily polluted by the pulp and paper industry and by chemical industries. A wood preservative, known as Ky-5, was manufactured in the upper reaches of the river between 1940 and 1984 causing severe pollution of river sediments with polychlorinated dibenzo-p-dioxins (PCDD) and diben- Environ Sci Pollut Res (2009) 16:95-105

- by Simo Salo and +1
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- Decision Making, Bioaccumulation, Risk Management, Rivers

Fluxes of dissolved forms of iron and manganese across the sediment-water interface were studied in situ in the Gulf of Finland and the Vistula Lagoon (Baltic Sea), and in the Golubaya Bay (Black Sea) from 2001 to 2005. Fluxes were measured using chamber incubations, and sediment cores were collected and sliced to assess the porewater and solid phase metal distribution at different depths. Measured and calculated benthic fluxes of manganese and iron were directed out of sediment for all sites and were found to vary between 70-4450 and 5-1000 µmole m − 2 day − 1 for manganese and iron, respectively. The behavior of the studied metals at various redox conditions in the near-bottom water and in the sediment was the main focus in this study. Our results show the importance of bottom water redox conditions for iron fluxes. We measured no fluxes at oxic conditions, intermediate fluxes at anoxic conditions (up to 200 μmole m − 2 day − 1 ) and high fluxes at suboxic conditions (up to 1000 μmole m − 2 day − 1 ). Total dissolved iron fluxes were generally dominated by iron(II). Contribution of iron(III) to the total iron flux did not exceed 20%. Obtained fluxes of manganese at all studied regions showed a linear correlation (r 2 = 0.97) to its concentration in the porewater of the top sediment layer (0-5 mm) and did not depend on dissolved oxygen concentrations of bottom water. Organically complexed iron and manganese were in most cases not involved in the benthic exchange processes.

- by Svetlana Pakhomova and +1
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- Geochemistry, Oceanography, Marine chemistry, Iron

Lake isolation studies provide a reliable method for reconstructing the sea-level history of areas affected by the glacio-isostatic land uplift. In this study, Late Holocene relative sea-level changes were investigated along the southern coast of Finland, Gulf of Finland in the Baltic Sea, by studying 11 isolation basins in four areas (Kirkkonummi, Orslandet, Tenhola and Prästkulla), which extend across 120 km of Finnish coastline that is characterised by a narrow archipelago. The methods employed were lithostratigraphic interpretation, diatom analyses and radiocarbon dating. Also used in this work are the results from three previously studied isolation basins with four 14 C dates.

- by Georg Haggrén
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- Earth Sciences, Marine Geology, Sea Level, Anomaly Detection

A cross-disciplinary approach to minimising the risks of maritime transport 345 Abstract: The maritime traffic in the Gulf of Finland is predicted to rapidly increase in the near future, which increases the environmental risks both through direct environmental effects and by increasing the accident risk. This paper describes a multidisciplinary modelling approach, where, based on growth predictions, the maritime traffic in the Gulf of Finland in the year 2015 is modelled and the accident risk, the direct environmental effects and the risk of environmental accidents are evaluated. Finally, the effects of national and international legislation and other management actions are modelled, to produce advice and support for governmental decision makers. In the modelling work, Bayesian Networks (BNs) are applied. The approach produces unique information on the accident risks and their effects separately for each marine route used, which enables efficient local risk control actions to be taken by the decision makers to decrease the probability of accidents.

- by Pentti Kujala and +3
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- Risk Management, Risk assessment, Urban And Regional Planning, Bayesian Networks

A rapid increase in maritime traffic together with challenging navigation conditions and a vulnerable ecosystem has evoked calls for improving maritime safety in the Gulf of Finland, the Baltic Sea. It is suggested that these improvements will be the result of adopting a regionally effective proactive approach to safety policy formulation and management. A proactive approach is grounded on a formal process of identifying, assessing and evaluating accident risks, and adjusting policies or management practices before accidents happen. Currently, maritime safety is globally regulated by internationally agreed prescriptive rules, which are usually revised in reaction to accidents. The proactive Formal Safety Assessment (FSA) is applied to risks common to a ship type or to a particular hazard, when deemed necessary, whereas regional FSA applications are rare. An extensive literature review was conducted in order to examine the opportunities for developing a framework for the GoF for handling regional risks at regional level. Best practices were sought from nuclear safety management and fisheries management, and from a particular case related to maritime risk management. A regional approach that sees maritime safety as a holistic system, and manages it by combining a scientific risk assessment with stakeholder input to identify risks and risk control options, and to evaluate risks is proposed. A regional risk governance framework can improve safety by focusing on actual regional risks, designing tailor-made safety measures to control them, enhancing a positive safety culture in the shipping industry, and by increasing trust among all involved.

- by Jouni Lappalainen and +2
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- Safety and Risk Management, Maritime Studies, Maritime Safety, Maritime Safety, Pollution and Shipping Management

The hypoxic zone in the Baltic Sea has increased in area about four times since 1960 and widespread oxygen deficiency has severely reduced macro benthic communities below the halocline in the Baltic Proper and the Gulf of Finland, which in turn has affected food chain dynamics, fish habitats and fisheries in the entire Baltic Sea. The cause of increased hypoxia is believed to be enhanced eutrophication through increased anthropogenic input of nutrients, such as nitrogen and phosphorus. However, the spatial variability of hypoxia on long time-scales is poorly known: and so are the driving mechanisms. We review the occurrence of hypoxia in modern time (last c. 50 years), modern historical time (AD 1950–1800) and during the more distant past (the last c. 10 000 years) and explore the role of climate variability, environmental change and human impact. We present a compilation of proxy records of hypoxia (laminated sediments) based on long sediment cores from the Baltic Sea. The cumulated results show that the deeper depressions of the Baltic Sea have experienced intermittent hypoxia during most of the Holocene and that regular laminations started to form c. 8500–7800 cal. yr BP ago, in association with the formation of a permanent halocline at the transition between the Early Littorina Sea and the Littorina Sea s. str. Laminated sediments were deposited during three main periods (i.e. between c. 8000–4000, 2000–800 cal. yr BP and subsequent to AD 1800) which overlap the Holocene Thermal Maximum (c. 9000–5000 cal. yr BP), the Medieval Warm Period (c. AD 750–1200) and the modern historical period (AD 1800 to present) and coincide with intervals of high surface salinity (at least during the Littorina s. str.) and high total organic carbon content. This study implies that there may be a correlation between climate variability in the past and the state of the marine environment, where milder and dryer periods with less freshwater run-off correspond to increased salinities and higher accumulation of organic carbon resulting in amplified hypoxia and enlarged distribution of laminated sediments. We suggest that hydrology changes in the drainage area on long time-scales have, as well as the inflow of saltier North Sea waters, controlled the deep oxic conditions in the Baltic Sea and that such changes have followed the general Holocene climate development in Northwest Europe. Increased hypoxia during the Medieval Warm Period also correlates with large-scale changes in land use that occurred in much of the Baltic Sea watershed during the early-medieval expansion. We suggest that hypoxia during this period in the Baltic Sea was not only caused by climate, but increased human impact was most likely an additional trigger. Large areas of the Baltic Sea have experienced intermittent hypoxic from at least AD 1900 with laminated sediments present in the Gotland Basin in the Baltic Proper since then and up to present time. This period coincides with the industrial revolution in Northwestern Europe which started around AD 1850, when population grew, cutting of drainage ditches intensified, and agricultural and forest industry expanded extensively.

- by Lovisa Zillen
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- Earth Sciences, Climate Change, Climate variability, Hypoxia
- by Alkis John Corres
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- Risk, Safety, COLLISION, Maritime traffic
- by Kerkko Nordqvist
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- Earth Sciences, Geoarchaeology, Coastal Geomorphology, Environmental Sciences

Since neural networks have been widely applied to the nonlinear transfer function approximation, we present an empirical neural network algorithm to estimate major parameters in surface waters from combined optical data and microwave data in the Gulf of Finland. Concurrent in situ surface water quality measurements, optical (Landsat TM) data and microwave (ERS-2 SAR) data were obtained in selected locations in August 1997. The TM and ERS-2 SAR data from locations of water samples were extracted and digital data were examined in numerous transformations. Although significant correlations were observed between digital data and chlorophyll-a (Chl-a), suspended sediment concentration (SSC), turbidity (Turb), and Secchi disk depth (SDD), application of neural networks appears to yield a superior performance in modeling transfer functions in this study area. Here, an empirical neural network algorithm is applied to estimate the transfer functions between the major characteristics of surface waters and the satellite optical and microwave data. The results show that the estimation accuracy for major characteristics of surface waters using the neural network is much better than those from regression analysis. The results also indicate that microwave data can assist to improve the estimation of these characteristics. Therefore, it may be possible to develop surface water quality algorithms in which microwave data are used as supplementary data to optical observations. However, this improvement of optical data retrieval algorithm is limited in this case study. The technique still needs to be refined in detail in order to detect differences within the typical range of these water quality parameters found in the area under study. D 2002 Elsevier Science Inc. All rights reserved. 0034-4257/02/$ -see front matter D 2002 Elsevier Science Inc. All rights reserved. PII: S 0 0 3 4 -4 2 5 7 ( 0 2 ) 0 0 0 0 9 -3

- by Sampsa Koponen
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- Algorithms, Remote Sensing, Water quality, Neural Networks

Cyanobacterial blooms are common in the Baltic Sea. They are dominated by Aphanizomenon flos-aquae and Nodularia spumigena and take place in July-August. Investigations of bloom development using different approaches have been carried out in the Gulf of Finland during recent years. The ship-of-opportunity technique allows to observe the upper layer dynamics from meso-to basin-wide scale with high temporal and spatial frequency at low cost. Unattended measurements on board a commercial ferry along a transect between Tallinn and Helsinki have been conducted for 3 years (1997)(1998)(1999). The influence of weather conditions-temperature and wind-on the cyanobacterial bloom development was investigated. The formation of cyanobacterial blooms was favoured by warm and calm weather, while in cold and windy conditions other species formed mass occurrences. Water temperature has been found to be the main factor controlling the initiation of the bloom, in general, while vertical stratification appeared to be the critical factor determining the intensity of the bloom at species level. The spatial distribution of the cyanobacterial bloom was determined rather by the wind-forced advection than by the possible vertical transport of nutrients in the areas of the observed upwelling events.

- by Inga Lips
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- Stratification, Biological Sciences, Environmental Sciences, Temperature
- by Kerkko Nordqvist
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- Archaeology, Geology, Mesolithic Archaeology, Neolithic Archaeology

The paper summarizes the current data on Neolithic Asbestos Ware at the southern
periphery of its distribution – the Karelian Isthmus and the southern Ladoga area, northwestern
Russia, to study communication networks within the territory of this phenomenon
and to trace its southern border.
Morphology and ornamentation of pottery with asbestos temper from 33 sites (including
very recent discoveries) was analysed and compared with the characteristics of the defined
Asbestos Ware types. All the main types of Neolithic Asbestos Ware defined on the
territory of Finland – Early Asbestos Ware, Typical Combed Ware with asbestos, Kierikki,
Pöljä – are presented in Karelian Isthmus including its southern part. Those territories were
well connected with the “core” of the Asbestos Ware tradition in the Saimaa area from the
beginning of its appearance. Asbestos Ware from the southern Ladoga shore sites resembles
both western and eastern (Karelian) traditions, shows some common traits with Volosovo
culture from the Upper Volga and ceramics from Modlona sites from Vologda region, but
also has local peculiarities. Analysis of sites distribution shows that the southern boundary
of spreading of the Late Neolithic Asbestos Ware follows that of the Early Asbestos Ware
and the Late Sperrings (Ka1:2) Ware. Although many spatial and chronological differences
in material culture, subsistence strategies and communication networks are visible within
time and space frames of the Asbestos Ware phenomenon, it may be assumed that the use
of the asbestos temper could be indicative of cultural relations that united certain territories.

- by Dmitriy Gerasimov
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- Neolithic Archaeology, Asbestos, Gulf of Finland, Ladoga

Geological hazards may threaten human life, may result in serious property damage, and may significantly influence normal development of biota. They are caused by natural endogenic and exogenic driving forces or generated by anthropogenic activities. An interaction of geological processes and intense anthropogenic activities, e.g., construction of buildings, harbors, oil and gas pipelines, hydroengineering facilities, and land reclamation, has resulted

- by Vladimir Zhamoida
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- Oil and gas, Land Reclamation, Integrated Management, Environmental Conditions

Pupal exuviae of marine intertidal midge Telmatogeton japonicus Tokunaga (Diptera: Chironomidae) were found in September 2008 from the Gulf of Finland, Baltic Sea. Previous records of the species in the Baltic Sea were from Sweden, Denmark, Germany and Poland. Telmatogeton japonicus is an alien species introduced to Europe from the Pacific Ocean. It probably uses shipping as the vector, since in north-western Europe it has first been detected near large seaports. This was also the case in the Gulf of Finland. Our findings suggests that the species' distribution extends further northeast in the Baltic Sea than understood before, and that the species is able to establish viable populations into fresh-brackish (salinity < 4 ‰) coastal habitats.

- by Yngve Brodin
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- Western Europe, Brackish Water, Ecology, Chironomidae

- by Floris Goerlandt
- •
- Engineering, System Identification, Traffic Simulation, Monte Carlo Simulation

The effect of coastal upwelling on the late summer pelagic environment, focusing on the two main bloom-forming filamentous cyanobacteria species, Aphanizomenon flos-aquae and Nodularia spumigena, was evaluated on the basis of field observations in July and August 1999 in the western Gulf of Finland. The study consisted of biological (chlorophyll a, phytoplankton, primary production), chemical (phosphate, nitrate, silicate), and CTD measurements at a fixed station and ten horizontal mesoscale surveys over the surrounding area. Available meteorological and open sea environment monitoring data (surface layer temperature and cyanobacteria biomass), as well as satellite data, were used for further interpretation of the results. An upwelling event was observed along the northern coast of the Gulf. It caused a 10 8C temperature drop and phosphate enrichment of the upper layer. The total biomass of phytoplankton declined in the area affected by the upwelled water. Within five days from the start of the upwelling chlorophyll a normalized primary production showed a slight increase, which was caused by a brief Mesodinium rubrum bloom. An observed initial decline of cyanobacteria biomass was due to offshore transport of the surface-dwelling populations. Due to the accumulation of N. spumigenacloser to the surface its biomass decrease was more pronounced than the biomass decrease observed for A. flos-aquae. The A. flos-aquae population residing in the upper part of the seasonal thermocline was brought up to the surface layer and growth of this inoculum was promoted by the phosphate input. An increase of A. flos-aquae biomass near the northern coast of the Gulf was observed after a three-week time lag when the upwelling had subsided. The structure of the phytoplankton community in the upwelling zone changed due to the upwelling, but was re-established within five days after the relaxation of upwelling. The growth of other phytoplankton species was most likely limited by nitrogen availability. D

- by Jaan Laanemets
- •
- Oceanography, Phosphorus, Seasonality, Marine

This paper investigates applicability of Bayesian networks to oil spill related situation as- sessment in order to facilitate the Net Environmental Benefit Analysis (NEBA) based de- cisions in selecting the best available oil spill response alternative, and in evaluating the threat or probable overall environmental impact of the spill. A crucial problem that deci- sion makers face in any oil

- by Jonne Kotta and +2
- •
- Oil Spill, Bayesian Inference, Environmental Impact, Bayesian Network

The aim of the study was to measure toxin production and growth of the cyanobacterium Anabaena sp. in the presence of competitor algae and grazers. The study was comparative, as it was repeated at two sites in the Baltic Sea. The results showed that growth and intracellular microcystin concentrations of Anabaena were significantly higher at the Bothnian Sea site than at the Gulf of Finland. Toxin concentrations of Anabaena were higher in the presence of chlorophyte Brachiomonas submarina than in incubations with cryptophyte Rhodomonas salina or copepod Eurytemora affinis. Chlorophyll content was higher in the presence of copepods. The results suggest that both growth and toxin production of Anabaena may be controlled by salinity, because salinity is lower at the Bothnian Sea site, whereas also other factors could have influenced the results. Our data are also in line with the hypothesis that possible allelopathic interactions (here measured as toxicity) are more probable in the presence of foreign species.► Intracellular toxin concentration of Anabaena was higher at the freshwater site ► Anabaena responded to foreign green algae by increasing toxin levels at the brackish-water site (Gulf of Finland) ► Anabaena showed higher growth at the freshwater site (Bothnian Sea)

- by Novia Sari
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- Crustacea, Interaction, Allelopathy, Biological Sciences

- by Margarita Kholkina
- •
- Pottery (Archaeology), Stone Age (Archaeology), Asbestos, Gulf of Finland

Water quality monitoring using remote sensing has been studied in Finland for many years. But there are still few discussions on water quality monitoring using remote sensing technology in support of water policy and legislation in Finland under the WFD. In this study, we present water quality monitoring using remote sensing in the Gulf of Finland, and focus on the spatial distribution of water quality information from satellite-based observations in support of water policy by a case study of nitrate concentrations in surface waters. In addition, we briefly describe instruments using a system of river basin districts (RBD), highlighting the importance of integrated water resources and riverbasin management in the WFD, and discuss the role of water quality monitoring using remote sensing in the implementation of water policy in Finland under the WFD.

- by Martti Hallikainen
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- Remote Sensing, Water, Water quality, Satellite Communications

In 1992, we discovered populations of the nonindigenous quagga mussel Dreissena rostriformis bugensis ͑Andrusov 1897͒ in the middle reaches of the Volga River. The same species was found in samples collected between 1994 and 1997 in the Volga delta and in shallow areas of the Northern Caspian Sea. D. r. bugensis always co-occurred with its more widespread congener, the zebra mussel D. polymorpha ͑Pallas 1771͒. The quagga mussel's contribution to total Dreissena abundance increased over time in the middle Volga reservoirs and Volga River delta. D. r. bugensis was common in the Volga portion of Rybinsk Reservoir during 1997 and, by 2000, it was in Uglich, Rybinsk and Gorky Reservoirs on the Upper Volga River. D. r. bugensis was neither found in Ivankov Reservoir, nor in terminal sections of the Volga-Baltic corridor including the eastern Gulf of Finland. Presently, all but the northern-most regions of the Volga River have been colonized by D. r. bugensis. We hypothesize that its introduction into the Volga River and Caspian basin occurred no later than the late 1980s via commercial shipping that utilized the Volga-Don waterway to navigate between the source Black-Azov Sea region and recipient areas on the Volga River. Larval drift likely contributed to establishment of populations at downstream sites, while human-mediated vectors may be responsible for introductions to upstream locations on the Volga River. We anticipate continued northward dispersal in conjunction with shipping activities.

- by Jim Muirhead
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- Aquatic Ecology, Ecology, Invasive Species, Range Expansion

During the 20th century, extensively hydrographic investigations had been performed in the Baltic Sea. One of the parameters that have been determined during these historic investigations of the Baltic Sea is the total alkalinity (A T ). In this study, this large data set is used together with a specifically developed box model to estimate the in-and outflows of salinity and A T within the different sub-basins. The Baltic Sea receives large amounts of freshwater through river runoff, and A T can be used as a chemical signature of the runoff as its concentration depends on the mineralogy of the drainage basin. Rivers entering the southern part of the Baltic Sea are draining areas rich in limestone, therefore having higher A T than rivers entering the northern part of the Baltic Sea where granite dominates the bedrock.

- by Anders Omstedt and +1
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- Earth Sciences, Biological Sciences, Salinity, Time Series Data
- by Inga Lips
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- Gulf of Finland, Abiotic factors

The founder event in a recently recolonized salmon population in the Baltic Sea (Gulf of Finland) was investigated. To identify the origin of the founders, four wild populations and two hatchery stocks were analysed using six microsatellite loci. The results of assignment tests and factorial correspondence analysis suggest that the initial recolonizers of the river Selja originated from the geographically nearest (7 km) wild population (river Kunda) but as the result of stocking activities, interbreeding between recolonizers and hatchery individuals has occurred in subsequent years. Although the hatchery releases are outnumbering the wild salmon recruitment in the Baltic Sea at present, our results suggest that the native populations may still have an important role in colonization processes of the former salmon rivers.

- by Tiit Paaver
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- Correspondence Analysis, Molecular Ecology, Biological Sciences, Molecular

Among engineers, risk is defined as a product of probability of the occurrence of an undesired event and the expected consequences in terms of human, economic, and environmental loss. These two components are equally important; therefore, the appropriate estimation of these values is a matter of great significance. This paper deals with one of these two components—the assessment of the probability of vessels colliding, presenting a new approach for the geometrical probability of collision estimation on the basis of maritime and aviation experience. The geometrical model that is being introduced in this paper takes into account registered vessel traffic data and generalised vessel dynamics and uses advanced statistical and optimisation methods (Monte Carlo and genetic algorithms). The results obtained from the model are compared with registered data for maritime traffic in the Gulf of Finland and a good agreement is found.

- by Jerzy Matusiak and +1
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- Engineering, Reliability Engineering, Traffic Safety, Mathematical Sciences
- by Stephan Gollasch
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- Biological invasions, Biological Sciences, Environmental Sciences, Biological

We present the results of multiparametric observations designed to follow the phytoplankton dynamics and interrelated physical, chemical and biological processes in the Gulf of Finland (Baltic Sea). Data were acquired by an autonomous moored water column profiler, an acoustic Doppler current profiler, a flow-through system installed aboard a ferry and by profiling and discrete water sampling aboard research vessels in July and August 2009. The main aim of the study was to investigate the processes responsible for the formation and maintenance of sub-surface maxima of phytoplankton biomass. We suggest that the environmental conditions caused by the prevailing atmospheric and oceanographic forcing (wind; vertical stratification; basin-wide, mesoscale and sub-mesoscale processes) are preferred by certain species/taxonomic groups and explain the migration patterns of phytoplankton. Nocturnal downward migration of phytoplankton with a swimming speed up to 1.6 mh −1 occurred when the community was dominated by the dinoflagellate Heterocapsa triquetra. The observed splitting of the population into two vertically separated biomass maxima suggests that the H. triquetra cells, which reached the sub-surface layers with high nutrient concentrations, experienced bi-diurnal or asynchronous (when swimming upwards) vertical migration. The most intense sub-surface biomass maxima, on some occa-sions with the biomass much higher than that in the surface layer, were detected in connection to the sub-mesoscale intrusions below the depth of the strongest vertical density gradient.

- by Inga Lips
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- Geology, Oceanography, Stratification, Swimming speed

We examined the factors underlying the deteriorating marine survival of a hatchery stock of Atlantic salmon, Salmo salar. The stock originated from the salmon population of the Neva River, which flows into the Gulf of Finland in the Baltic Sea. During 1981During -2005,000 Carlin-tagged Neva salmon smolts were released in the Gulf of Finland and the Bothnian Sea. We investigated the effects of fin damage, smolt length, sexual maturity (precocious maturation), smolt year, the time (days) between tagging and release and the release date on survival. The survival of the released smolts clearly decreased towards present. In earlier years, larger smolts tended to survive better than smaller ones, but the advantage of a large smolt size decreased in the later years of the study. No significant effect of dorsal fin damage on survival was detected. On average, immature smolts survived better than precocious males, and the proportion of precocious males increased over time. However, the proportion of precocious males among the tagged fish did not explain the decreasing trend in marine survival. Release year was the most important predictor of the long-term decreasing trend in marine survival. The optimal tagging time varies: in some years smolts tagged in the autumn survived better, while in other years spring taggings were more advantageous. For most years, a late release (in May or June) was more favourable than an early one (in April). As the releases were mainly carried out quite early in the spring in the last 13 years of the study, an unfavourable timing of release may partly explain the lower marine survival recorded during this period.

- by Matti Salminen and +2
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- Fisheries, Ecology, Atlantic Salmon, Fisheries Sciences

- by Pentti Kujala and +2
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- Bayesian Networks, Risk Analysis, Ropax, Gulf of Finland

The development of a deep chlorophyll maximum (DCM) at a depth of 30-35 m was followed during a 15-d case study in July 1998 at the entrance to the Gulf of Finland. The study consisted of three 18-24-h periods of biological (chlorophyll a, phytoplankton, primary production), chemical (nitrate, phosphate) and physical (CTD, turbulence, vertical particle size distribution) measurements at an anchor station and six mesoscale towed CTD/ fluorometer mappings over the surrounding area. Exceptionally cold and windy weather led to a red tide of the dinoflagellate Heterocapsa triquetra instead of the cyanobacterial bloom that frequently occurs in late summer. Comparison of the estimated amount of nitrogen required for an H. triquetra bloom biomass with external loading affirmed that the bloom had been formed on the basis of the nitrate pool below the thermocline. The development of the bloom, therefore, led to the extremely deep nitracline. The DCM formed by H. triquetra developed at the top of the nitracline at an illumination of Ͻ0.1% of the sea surface illumination. A temperature-salinity analysis showed that the DCM was not caused by intrusions from inshore regions. It was concluded that the DCM was formed as a result of changing migratory behavior of H. triquetra after an upwelling event that fertilized the upper layer with phosphorus.

- by Kaisa Kononen
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- Earth Sciences, Limnology, Biological Sciences, Phosphorus
- by Dmitriy Gerasimov
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- Earth Sciences, Geology, Oceanography, Geoarchaeology

The maritime traffic in the Gulf of Finland is predicted to rapidly increase in the near future, which increases the environmental risks both through direct environmental effects and by increasing the accident risk. This paper describes a multidisciplinary modelling approach, where, based on growth predictions, the maritime traffic in the Gulf of Finland in the year 2015 is modelled and the accident risk, the direct environmental effects and the risk of environmental accidents are evaluated. Finally, the effects of national and international legislation and other management actions are modelled, to produce advice and support for governmental decision makers. In the modelling work, Bayesian Networks (BNs) are applied. The approach produces unique information on the accident risks and their effects separately for each marine route used, which enables efficient local risk control actions to be taken by the decision makers to decrease the probability of accidents.

- by Sakari Kuikka
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- Risk Management, Risk assessment, Urban And Regional Planning, Bayesian Networks

Velocity field simulated by a circulation model with extremely high horizontal resolution (the grid bin is 232×232 m) in the Gulf of Finland during a period of summer upwelling events is used to calculate advection of floating Lagrangian particles that are uniformly distributed on the sea surface initially. For a relatively short time of advection τ (of the order of one day), the particles are found to gather within narrow, elongated stripes characterized by extremely high, positive values of vorticity, Finite-Time Lyapunov Exponent, and lateral thermohaline gradients module (fronts). The clustering rate, defined as the time derivative of the standard deviation of normalized particle concentration, tends asymptotically at small τ to the standard deviation of flow divergence. The standard deviation of flow divergence, in its turn, displays a considerable growth with the refinement of the model grid, confirming the paramount role of submesoscale dynamics in clustering of floating stuff. At large τ, the probability density function of floating particle concentration is shown to tend to lognormality. Based on the backward-time integration of the Lagrangian velocity convergence, a criterion for finite-time clustering is introduced.

- by Germo Väli and +1
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- Baltic Sea Region Studies, Numerical Modelling, Ocean Modeling, Baltic Sea

An increase of xenodiversity in plankton and benthos in the eastern Gulf of Finland was observed from 1998 to 2004. Nonindigenous species account for 4.8% of all species found and up to 96% of total biomass. Invasive benthic omnivores, the alien amphipods Gmelinoides fasciatus and Pontogammarus robustoides and the predaceous fish Perccottus glenii with their versatile diets strongly affect the community structure. Invasive sessile seston-feeders that directly (through grazing and water clearance) and indirectly (through recycling of nutrients) interact with other ecosystem components, are mainly represented by the zebra mussel Dreissena polymorpha, which affect the structure of benthic and planktonic communities as well as benthicpelagic coupling. The invasive predatory cladocerans Cercopagis pengoi and Evadne anonyx and larvae of D. polymorpha are only temporary components in the zooplankton, which is limiting their overall effect. Alien benthic bioturbators, the polychaetes Marenzelleria neglecta and the oligochaete Tubificoides pseudogaster account for a high proportion of total abundance and biomass but their effects on native species need further research.

- by Alexey Maximov
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- Oceanography, Community Structure, Ecosystem Function, Gulf of Finland

A 2-week multidisciplinary study of the physical, chemical, and biological mechanisms controlling the initiation of the late summer blooms of the diazotrophic cyanobacteria, Aphanizomenon jlos-aqua2 Ralfs and Nodularia spumigena Mertens, in the Baltic Sea was carried out in a frontal region at the entrance to the Gulf of Finland in July 1993. The front is formed by inflowing sa'itier waters of the northern Baltic proper and outflowing fresher waters from the gulf, and its position and shape are largely controlled by wind conditions. In general, the waters of the northern Baltic proper are less stratified than the outflowing lesssaline waters. At the time of the study, the two major water masses differed in terms of phytoplankton community structure, both at species level and at the level of functional groups. Wind-induced vertical mixing was instrumental in bringing nutrient pulses to the upper mixed layer in the less-stratified, high-saline water mass. Nutrient pulses were followed by enhancement of primary productivity and assimilation number (primary productivity/Chl a) in cyanobacterial (> 20 pm) and flagellate (< 20 vrn) size fractions. It is proposed that mesoscale blooms of A. flos-aquae benefit from the nutrient-pulsing events. Calm weather and solar heating, as reflected by rising temperatures in the upper mixed layer and overriding of water masses in the frontal region, resulted in substantial shallowing of the upper mixed layer, which initiated the bloom of N.

- by Jorma Kuparinen and +1
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- Earth Sciences, Limnology, Biological Sciences, Environmental Sciences

We use molecular markers, feeding experiments, and stable isotopes to understand trophic interactions between native mysids, Mysis mixta and Mysis relicta, and a recent invader to the Baltic Sea, the cladoceran Cercopagis pengoi. In feeding experiments, both mysid species ingested C. pengoi at a maximum of 16 prey mysid 21 d 21 and a specific consumption rate of 0.15 d 21 , similar to rates reported for predation on other prey species. The frequency of predation on C. pengoi assayed by molecular diet analysis of field-collected mysids varied between 5% and 43% depending on mysid size and species. Surprisingly, it was consistently higher in juveniles than in adults and in M. mixta than in M. relicta. The results of stable isotope analysis corroborate those of feeding experiments and molecular analysis and indicate a higher contribution of C. pengoi to the nutrition of juveniles and M. mixta. These ontogenetic and interspecific differences in mysid predation on C. pengoi are likely to reflect differences related to their different migratory behavior. Thus, despite its low relative abundance, C. pengoi is readily consumed by mysids; this may impact lower food web interactions and the nutrition of mysids in the invaded ecosystems.

- by Elena Gorokhova
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- Earth Sciences, Stable Isotope Analysis, Crustacea, Invasive species ecology
- by Lovisa Zillen
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- Earth Sciences, Climate Change, Climate variability, Hypoxia

- by Martti Hallikainen
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- Remote Sensing, Water, Water quality, Satellite Communications