Bay Of Gdansk Research Articles

Nitrogen-fixing sulfate reducing bacteria in shallow coastal sediments under simulated resuspension

Nitrogen (N2) fixation by heterotrophic non-cyanobacterial diazotrophs is common in marine deep-sea sediments. However, in shallow coastal areas, where resuspension of sediments is extensive, the magnitude of sediment-associated N2 fixation during resuspension is unknown. We examined nitrogen fixation in dark slurry incubations with sediments (0–5 cm and 0–10 cm depths) under simulated resuspension from five shallow stations (water depth <1 m) and an anoxic site in the Bay of Gdansk (109 m) in the Baltic Sea. Abiotic variables and the composition of nitrogen fixing organisms (diazotrophs) were measured at the study sites. To estimate the contribution of nitrogen fixing sulfate reducing bacteria to total nitrogen fixation, parallel incubations with sodium molybdate as inhibitor were performed. Our data show low but variable nitrogen fixation rates (n.d. - 23.7 nmol N g−1 d−1), promoted in small-grained sediments associated with increased organic carbon content and high nutrient concentrations in pore waters. Highest nitrogen fixation at the shallow sites was encountered in the upper 0–5 cm of the sediments while rates were negligible below. Sulfate reducing bacteria (e.g. Desulfobacterales and Desulfovibrionales) were responsible for most of the heterotrophic nitrogen fixation and appear as key players for pelagic N2 fixation during resuspension. Our study reveals an important sediment – water coupling, which may be accentuated by the increased storms and resuspension events predicted for the Baltic Sea region.

Seasonal and Spatial Changes of Primary Production in the Baltic Sea (Europe) Based on in situ Measurements in the Period of 1993–2018

The seasonal and spatial variability of primary production (PP) measured using 14C method in two regions: open waters of the Baltic Sea and the Gulf of Gdansk were discussed. The statistical analyses of 26-years dataset (from 1993 to 2018) allow to confirm some regularities of productivity and find some features resulting mainly from changing environmental conditions like solar insolation, temperature, and chlorophyll a concentration. In the dataset, production values varied from 0.005 to 7.8 g C m–2 day–1 in open waters and from 0.07 to 12.9 g C m–2 day–1 in the Gulf of Gdansk. Analysis showed that PP in open waters were 6–17% lower than in Gulf of Gdansk in most of the cases. In both regions, the periods of intense productivity in spring and autumn were observed, but vegetation begins a month earlier in the Gulf of Gdansk than in open waters. Probably the accumulation of nutrients after the winter causes the spring bloom (April–May) in both regions to be more intense (even two times higher) than the autumn bloom (September–October) associated with favorable hydrological conditions resulting from summer insolation. The presented results showed slight downward trends in productivity in both regions, the most visible in the spring in the Bay of Gdansk. This confirms the recent reports on a possible improvement in the eutrophication state of the Baltic Sea.

Lagrangian Residence Time in the Bay of Gdańsk, Baltic Sea

The impact of synoptic scale and mesoscale variability on the Lagrangian residence time (LRT) of the surface water in the Bay of Gdansk was investigated using the results from an eddy-resolving model. The computed LRT of 53–60 days was up to four times longer than the estimated flushing time reported by Witek et al. (2003). The highest residence times were those of Puck Bay and near the coast, below 50 m water depth, especially during the winter. These sites also had the highest annual mean in LRT. During the summer, when the level of biological activity is high, the LRT distribution was very heterogeneous and patchy, possibly due to the eddy field and to variable wind forcing. Long-term run tracking of the inflowing water from the Vistula River showed a broad spectrum of tracer distribution. The potential impact of a much higher LRT on the near-coastal nitrogen cycle, coastal filter function and genetic differentiation is discussed, and the consequences for coastal zone management are considered. The incorporation of residence time into the Marine Strategy Framework Directive descriptors would result in an improved, unbiased evaluation of good environmental status.

Assessment of the Positioning Accuracy of DGPS and EGNOS Systems in the Bay of Gdansk using Maritime Dynamic Measurements

Differential Global Positioning Systems (DGPS) and the European Geostationary Navigation Overlay Service (EGNOS) are included in a group of supporting systems (Ground-Based Augmentation System (GBAS)/Space-Based Augmentation System (SBAS)) for the American GPS. Their main task is to ensure better positioning characteristics (accuracy, reliability, continuity and availability) compared to GPS. Therefore, they are widely applied wherever GPS failures affect human safety, mainly in aviation, land and marine navigation. The aim of this paper is to assess the predictable positioning accuracy of DGPS and EGNOS receivers using a vessel manoeuvring in the Bay of Gdansk. Two receivers were used in the study: a Simrad MXB5 (DGPS) and a Trimble GA530 (EGNOS), which were simultaneously recording their coordinates. The obtained values were compared with the trajectory computed using a geodetic Global Navigation Satellite System (GNSS) receiver (Trimble R10) connected to a GNSS network, ensuring an accuracy of 2–3 cm (p = 0·95). During a four-hour measurement session, the accuracy statistics of these systems were determined based on around 11,500 positionings. Studies have shown that both positioning systems ensure a similar level of accuracy of their positioning services (approximately 0·5–2 m) and they meet the accuracy requirements set in published standards.

Impact of Macrofaunal Communities on the Coastal Filter Function in the Bay of Gdansk, Baltic Sea

Abstract During three cruises to the Bay of Gdansk, Baltic Sea, the fauna, porewater and bottom water were sampled at stations parallel to the shore and along a transect offshore. Diffusive porewater fluxes were calculated and related to the total net fluxes (TNF) of nutrients. The TNF comprise all nutrients that reach the bottom water from the sediment including diffusive nutrient efflux, discharge from macrozoobenthos and microbial activity. They were determined during in situ incubations using a benthic chamber lander, which is rarely done in coastal research. The lander restricts the physical influence of currents and waves on the sediments and only allows nutrient fluxes due to bioturbation by natural communities. Strong benthic-pelagic coupling in the shallow coastal zone suggested a crucial filter function for the bioturbated coastal sediments, which are separated from muddy deep sediments with little or no fauna at a depth of 50 m; in between is a small intermediate zone. While diffusive fluxes were highest at intermediate and offshore stations, TNF were highest at sandy coastal stations, where reservoirs of dissolved nutrients were small and sediments almost devoid of organic material. The greatest impact of macrofauna on sedimentary fluxes was found at stations whose communities were dominated by deep-burrowing polychaetes. The largest TNF were measured directly at the mouth of the Vistula River, where riverine food and nutrients supplies were highest. Macrofauna communities and sediment variables can thus serve as descriptive indicator to estimate the extent of the coastal filter. Finally, based on the total areal size of the different sediment types, annual efflux for the complete coastal zone of the Gdansk Bay was estimated to be 6.9 kt N, 19 kt Si, and 0.9 kt P. Compared to the muddy offshore area, which is twice as large, these amounts were similar for P and threefold higher for N and Si.

River plume and bottom boundary layer – Hotspots for nitrification in a coastal bay?

Coastal zones, impacted by major rivers, comprise distinct environments, such as river plumes and bottom boundary layers (BBL). These environments are characterized by high nutrient concentrations and high microbial activities and thus offer favourable conditions for nitrification, a key process in the coastal nitrogen cycle. Because nitrification provides substrates for both primary production and denitrification, elucidation of its magnitude and regulation is crucial for understanding the nitrogen cycle in coastal zones. During three research cruises covering three seasons, the enhancement of nitrification rates and their regulation by environmental variables, including salinity, temperature, oxygen, and inorganic and organic nitrogen were investigated in river plume and BBL of the Vistula Estuary (Bay of Gdansk, Southern Baltic Sea). Nitrification rates were not enhanced in the river plume (39 ± 38 nmol L−1 d−1) compared to coastal surface water (45 ± 18 nmol−1 d−1) but the relationship to salinity and particulate organic nitrogen changed, suggesting different regulatory mechanisms along the salinity gradient. Nitrification rates in the BBL covered a range from 1 to 227 nmol L−1 d−1 and did not differ seasonally. NH4+ turnover was dominated by assimilation into biomass in summer and by nitrification in winter and spring. In summer, rates were only slightly enhanced in the BBL and clearly related to particulate organic nitrogen and carbon concentrations, indicating particle attachment of nitrifiers and close coupling to organic matter degradation. The lack of correlations between nitrification and environmental variables in winter and spring suggested other regulatory mechanisms than in summer. Short-term changes, including the oxygenation of anoxic deep offshore water and particle resuspension clearly enhanced nitrification and further highlighted the variable mechanisms regulating nitrification in the Bay of Gdansk. Although nitrification rates did not greatly differ between seasons or water layers, the variability in regulatory mechanisms and the seasonal switch in NH4+ recycling are likely to have implications on coastal N-turnover and hence on the filter function of coastal waters.

Architectural Symbols of a City – Case Study

The identity of a city is understood as a collection of individual features, which give the city its individual character and distinguish it from other places; it undoubtedly constitutes a cultural value, which should be cherished. A city is made special thanks to its geographical location, landscape values, urban layout and – architecture. In the case of Sopot – a spa located on the Bay of Gdansk, the mosaic of the above-mentioned features has created a unique image of a seaside resort. Sopot architecture is distinguished by a complex of buildings dating back to the turn of the 20th century, which is the largest one in the country. The architecture of the city is dominated by eclectic influences, mainly Neo-gothic and Art-Nouveau, as well as early modernism; it is also possible to find examples of holiday architecture, with characteristic wooden verandas. The identity of a city and its image is not always permanent and unchanging in time. In the case of Sopot, only 5% of the existing buildings were damaged during the Second World War. However, the most important ones, characteristic for the city and located in its representative part, were destroyed. The war was followed by a period of economic stagnation and isolation from the free world, which lasted for almost 45 years. At that time there were no comprehensive revitalisation projects for this prestigious area of the city. The buildings constructed in the 1960s did not create an architecturally and spatially coherent urban tissue. The situation changed in 1989, when Poland regained its sovereignty. Since that time numerous investment projects have been carried out in Sopot, including the prestigious ones, located in the representative part of the city. This paper has been devoted to Sopot architecture – both historic and modern, the dominating architectural trends and the issues connected with the coexistence of “the old and the new”. The buildings characteristic for the city, historic and modern ones, which constituted (or constitute at present) important landmarks in the urban area, and which were (or still are) the city symbols, have been analysed. Unfortunately, some of the buildings constructed over the last 25 years in the representative part of the city are not consistent with its unique character. The decisions made by investors, architects, city authorities and the monument preservation office may have serious negative effects; they may cause degradation of urban space and, as a result, harm its image. In the summary of this paper possible dangers connected with realising investments in the most important city locations, the ones with historic context, have been indicated, and recommendations aimed at elimination of such dangers have been presented. The priority – particularly in cities with an established, unique image – should be to ensure that architectural and cultural heritage is preserved, while new architecture should speak with modern language and introduce new values to its historic surroundings.

Spatio-temporal dynamics of cod nursery areas in the Baltic Sea

In this study the drift of eastern Baltic cod larvae and juveniles spawned within the historical eastern Baltic cod spawning grounds was investigated by detailed drift model simulations for the years 1971–2010, to examine the spatio-temporal dynamics of environmental suitability in the nursery areas of juvenile cod settlement. The results of the long-term model scenario runs, where juvenile cod were treated as simulated passively drifting particles, enabled us to find strong indications for long-term variations of settlement and potentially the reproduction success of the historically important eastern Baltic cod nursery grounds. Only low proportions of juveniles hatched in the Arkona Basin and in the Gotland Basin were able to settle in their respective spawning ground. Ocean currents were either unfavorable for the juveniles to reach suitable habitats or transported the juveniles to nursery grounds of neighboring subdivisions. Juveniles which hatched in the Bornholm Basin were most widely dispersed and showed the highest settlement probability, while the second highest settlement probability and horizontal dispersal was observed for juveniles originating from the Gdansk Deep. In a long-term perspective, wind-driven transport of larvae/juveniles positively affected the settlement success predominately in the Bornholm Basin and in the Bay of Gdansk. The Bornholm Basin has the potential to contribute on average 54% and the Bay of Gdansk 11% to the production of juveniles in the Baltic Sea. Furthermore, transport of juveniles surviving to the age of settlement with origin in the Bornholm Basin contributed on average 13 and 11% to the total settlement in the Arkona Basin and in the Gdansk Deep, respectively. The time-series of the simulated occupied juvenile cod habitat in the Bornholm Basin and in the Gdansk Deep showed a similar declining trend as the Fulton’s K condition factor of demersal 1-group cod, which may confirm the importance of oxygen-dependent habitat availability and its effect on density dependence as a process relevant for recruitment success.

Modeling of Emissions and Dispersion of Harmful Compounds from Marine Main Propulsion Diesel Engines of Vessels Navigating in Specified Water Basins

Abstract The article presents the results of the first nationwide study of a pro-ecological character, including the problem of the impact of shipping (in a particular basin) on the terrestrial human environment. Shipping in the waters of the Bay of Gdansk is taken as an example of the real system and a detailed identification of the operating conditions for the vessels has been undertaken. Data were obtained from the analysis of information gathered by surveillance systems of vessel traffic (such as Automatic Identification System - AIS) for the complete identification of parameters and characteristics of shipping traffic in the form of deterministic and statistical mathematical models. On the basis of these mathematical models of the emission of harmful exhaust emissions from marine engines have been developed. Models of the spread of exhaust gas are based on the models of Gauss, Euler and Lagrange. Their use has enabled a scientific tool to evaluate the contribution of immission of harmful compounds in the global immission of pollutants in the atmospheric air of the Tri-city agglomeration to be obtained.

Effect of Wind and Hydrographic Conditions on the Transport of Vistula Lagoon Waters Into the Baltic Sea: Results of a Combined Experiment

The influence of wind and hydrodynamic processes on the spreading of turbid waters from the Vistula Lagoon into the Baltic Sea was studied. Our research is based on joint analyses of remote sensing data and those from concurrent in situ measurements of the three-dimensional structure of the outflow. A strong difference in the water optical properties of the Baltic Sea and the Vistula Lagoon caused by an intense summer bloom of cyanobacteria allowed studies of the evolution and transformation of the outflow in mid-July–early August 2014 using Ocean Color satellite data. Our in situ measurements revealed that waters from the Vistula Lagoon were exclusively present in the upper water layer. The study was conducted under various wind and, therefore, under different upwelling/downwelling conditions, thereby determining different patterns of wind-driven currents, which enabled us to assess their impact on the propagation of the lagoon outflow. One of these patterns was reaching to the south, along the Vistula Spit, and another one reaching to the north, along the Sambia Peninsula. We show that the main spreading direction of the plume strongly coincides with that of wind-driven currents. However, if vortical structures are present in the Bay of Gdansk, they also affect the plume transformation, and that should be taken into account when the propagation of water pollution is forecasted.

Selenium content in European smelt (Osmerus eperlanus eperlanus L.) in Pomerania Bay, Gdansk Bay and Curonian Lagoon

Migratory smelt (Osmerus eperlanus eperlanus L.) may be perceived as a valuable indicative organism in monitoring the current environmental status and in assessment of a potential risk caused by selenium pollution. The aim of the study was to compare the selenium content in the European smelt from the Bay of Pomerania, Gdansk, and the Curonian Lagoon. The experimental material consisted of smelt samples (muscle) caught in the bays of Gdansk and Pomerania and the Curonian Lagoon (estuaries of the three largest rivers in the Baltic Sea basin: the Oder, the Vistula and the Neman). A total of 133 smelt were examined (Pomerania Bay n = 67; Gdansk Bay n = 35; Curonian Lagoon n = 31). Selenium concentrations were determined spectrofluorometrically. The data were analyzed statistically using one-way analysis of variance, calculated in Statistica PL software. The region of fish collection significantly affected the content of selenium in the examined smelts. The highest content of selenium was observed in smelt caught in the Bay of Gdansk (0.236 µg g -1 w.w.), then in smelt from the Pomeranian Bay (0.165 µg g-1 w.w.), and the lowest in smelt obtained in the Curonian Lagoon (Lithuania) (0.104 µg g-1 w.w.). The low concentrations of selenium recorded in the smelt show that there is a deficiency of this element, especially in the Curonian Lagoon (Lithuania). Geochemically, Poland and Lithuania are selenium deficient areas. Migratory smelt may serve as indicative organisms of environmental levels of selenium.

Selected aspects of application of dual fuel marine engines

The paper presents examples of application of dual fuel marine engines based on the expertise of the largest marine engine manufacturers. The fueling systems of these engines have been presented as fueled with fuel gases in various combinations with liquid fuels. Examples of the application of dual fuel engines in vessels as well as variants of the powertrains have been shown. The results of own simulation research (Monte Carlo method) have also been presented related to the NOx emission from a variety of vessels operating in the area of the Bay of Gdansk proving that the use of engines fueled with fuel gas may indeed reduce the emission of NOx from marine vessels operating in this area.

Endangered anadromous lampreys in the southern Baltic Sea: spatial distribution, long-term trend, population status

We analysed ~310 records of river lampreys Lampetra fluviatilis (Linnaeus, 1758) (~19 977 663 specimens) and 54 records of sea lampreys Petromyzon marinus Linnaeus, 1758 (~86 specimens) for the southern parts of ICES Subdivisions 22 and 24 to 26 in the Baltic Sea cover- ing the period 1649 to 2005. Most sea lamprey records came from Subdivisions 22 and 24. The major- ity of river lamprey records stem from Subdivisions 24 and 26. We found no distinct temporal trend for sea lamprey stock development. However, a long-term trend showing decreasing catches of river lamprey was detected, indicating a stock decrease of this species from 1887 to 1999. The largest numbers of lamprey (largely river lamprey but may include some sea lamprey as species were not distinguished in the past) were caught in the period 1890 to 1919. Approximately 82% of the total lamprey catch in our study area was made in Subdivision 26. Roughly 65.3% of the mean annual yield of lampreys came from the lower Vistula River, the Vistula Lagoon and the Bay of Gdansk. The river lamprey was mainly distributed in estuarine and coastal marine areas. Offshore records of sea lamprey were also rare. From 1990 to 2005, most river lamprey records and recorded individuals orig- inated from the Szczecin Lagoon and its adjacent waters, demonstrating the present importance of these waters for their spawning migrations. Of 9 known river lamprey spawning sites, 5 were found in the Peene River system which flows into the Szczecin Lagoon. At present, no sea lamprey repro- duction site is known from rivers of the German Baltic Sea area. A rebuilding programme is required for the river lamprey; this should definitely contain measures to restore lost spawning sites and the connectivities within the river systems where spawning populations still occur. Protected areas in estuarine waters with important lamprey migration routes may be an additional measure for the conservation of these anadromous species.

Groundwater flow modelling of multi-aquifer systems for regional resources evaluation: the Gdansk hydrogeological system, Poland

In order to evaluate groundwater regional resources, a mathematical model of the Gdansk hydrogeological system (Poland) was developed. The research area covers about 2,800 km2. Groundwater occurs in Cretaceous, Paleogene and Neogene formations. The recharge zone is situated in the glacial upland of the Kashubian Lake District. The discharge zone spreads over the lowlands of Gdansk and beneath the Bay of Gdansk (Baltic Sea). The MODFLOW program was used to develop a three-dimensional steady-state model on the basis of data from over 1,700 boreholes. The research area was digitalized as a square network of sides 200 m in length. Simplification of groundwater occurrence allowed four aquifers to be distinguished: upper Pleistocene, Pleistocene-Miocene, Oligocene-Eocene, and Cretaceous and also four intervening aquitards. The mathematical model calculations showed that the system is recharged mainly by precipitation (infiltration recharge is 136 mm/year). The precipitation recharge amounts to 1,045,440 m3/day. The other part of the inflow constitutes lateral flows from beyond the area of research and also to some extent from losing rivers and lakes. The runoff from the system takes place mainly through gaining streams and through lateral outflow including under-sea and lake discharge.

Hoarfrost and rime chemistry in Poland—An introductory analysis from meteorological perspective

Hoarfrost and rime analysis was based on the collection of samples between 2003 and 2006 from 8 sites, which represent both lowland (northern) and mountainous (southern) parts of Poland. On the other hand 4 of these sites belong to “urban” and 4 to “rural” category. pH, conductivity, SO42−, NO3−, Cl−, H+, NH4+, Ca2+, Mg2+, Na+, K+ have been determined in order to study the chemistry of hoarfrost and rime. Higher total inorganic ionic content (TIC) in hoarfrost and rime (2.46 meq·l−1 and 1.23 meq·l−1 respectively) was observed when compared with precipitation (0.37 meq·l−1). Large variability of TIC and chemical composition of individual samples were typical at each of the measurement sites depending on emission patterns, atmospheric conditions and local terrain topography. Higher concentrations of both hoarfrost and rime occurred in southern (mountainous) rather than in northern (lowland) part of Poland which can be explained by worse pollutant dispersion conditions in the south. The surprisingly low hoarfrost concentrations in urban coastal stations in the area of the Bay of Gdansk were attributed to the cleaning effect of nocturnal breeze-type circulation, best pronounced in cool part of the year. Due to relatively high pollutant concentration and long duration, hoarfrost and rime are at least significant factors in environmental processes in different ecosystems in Poland.

Distribution and Host Range of the Microsporidian Pleistophora mulleri

Microsporidia of the genus Pleistophora are important parasites of fish and crustacea. Pleistophora mulleri has been described previously as a parasite of the gammarid amphipod crustacean Gammarus duebeni celticus in Irish freshwater habitats. Through a survey of European G. duebeni populations, P. mulleri was found to be widely distributed in the western British Isles (Wales, Scotland, and the Isle of Man), and populations of the subspecies Gammarus duebeni duebeni as well as G. d. celticus were infected. Pleistophora infections were also detected in G. d. duebeni sampled from the Bay of Gdansk on Poland's Baltic coast, indicating a wide distribution of Pleistophora in European G. duebeni. Sequencing and phylogenetic analysis of the 16S rRNA, 18S rRNA, and Rpb1 genes of P. mulleri suggest that this species may be synonymous with P. typicalis, a parasite of fish. These findings suggest that amphipod crustaceans may act as intermediate or reservoir hosts for microsporidian parasites of fish.

Return of twaite shad Alosa fallax (Lacépède, 1803) to the Southern Baltic Sea and the transitional area between the Baltic and North Seas

The status of twaite shad was investigated within the Southern Baltic Sea (ICES subdivision 22–27) and transitional area between the Baltic and North Seas (division IIIa). The following sources of data were analysed: (i) commercial catch statistics and relevant publications, (ii) records from ichthyological museum collections, (iii) records from recent commercial and recreational fisheries, (iv) research fisheries with trawls. A total of 476 records of twaite shad including more than 16 million individuals were obtained for the time between the years 1836 and 2005. About 72.9% of all records originated from commercial catch statistics and publications, whereas 18.9% were received from ichthyological collections. Research fisheries provided 6.3%, and 1.9% of the records were obtained from recent commercial and recreational fisheries. Most records of twaite shad were estimated for subdivisions 24 (45.2%) and 26 (35.5%). From 1836 to 1959, 29.6% of the records date from the period until 1899. 70.4% of the records of twaite shad originate from the twentieth century until 1959. The mean annual catch of twaite shad between 1891 and 1959 amounted to 86,674 kg within subdivisions 24–26 of the Southern Baltic Sea. Catch data show an approximately 20-year-cyclicity of maximum yields and minimum catches, respectively. The maximum annual yield of twaite shad in subdivisions 24–26 (474,700 kg) was registered in 1940, the minimum annual yield was estimated in 1958 (10 kg). In the 1950s, the annual catches of twaite shad declined sharply. Until 1960 twaite shad catches and records originated mainly from the Pommeranian Bay/Pommeranian Coast and adjacent waters including the Szczecin Lagoon (subdivision 24), the Bay of Gdansk, Vistula Lagoon and Vistula Spit (subdivision 26) and from the Curonian Lagoon and Curonian Spit (subdivision 26). The highest catches of twaite shad originated from the area of Curonian Lagoon/Curonian Spit from 1941 to 1960. Seasonal catches of twaite shad showed maximum values from May to July. From 1960 to 1989, only four records of A. fallax were registered in the Southern Baltic Sea which originated from German coastal waters in subdivisions 22 and 24. A total of 107 records of twaite shad was obtained in subdivisions 20–27 from 1990 to 2005. Most of these recent records originate from a twaite-shad stock in subdivisions 24, 25 and 26. There are indications which suggest a separate stock of twaite shad in subdivisions 20 and 21. Disappearance and recovery of twaite shad stocks were probably caused by the following factors: construction of barriers in rivers with spawning sites of twaite shad; habitat destruction in those rivers as consequence of gravel extraction and reengineering scheme to improve navigation and for flood defence purposes, water pollution in the lagoons of the Southern Baltic and in their tributaries, commercial fishery in the Southern Baltic and climatic variation in the Baltic Sea basin south of the latitude of 60° N.

A GIS-based WFD oriented typology of shallow micro-tidal soft bottom using wave exposure and turbidity mapping

Our GIS based project aims at producing a classification scheme to develop a typology of the bottom of the Bay of Gdansk in the southern Baltic. The typology was based on the abiotic factors which are used to define water body types by the European Water Framework Directive (WFD). Significance analysis of particular factors has shown that within the discussed area wave exposure seems to play the most important role. All other factors are to a greater or lesser degree correlated with these two. Taking into consideration the shallows and the varied coastline of the investigated area it was decided to make use of the SWAN numerical wave model to determine the influence of wave impact upon the bottom. The model was used to produce raster maps of orbital velocity near the bottom for each wind scenario. With the help of the GIS analysis the maps were turned into layers: the mean velocity and the maximum velocity at the bottom. To produce the layer of yearly amount of solar radiation a GIS model was built which main parameters were the layer of depth and three layers of turbidity for three seasons. The layers of the maximum orbital velocity and of the solar radiation at the bottom were then used in a classificatory procedure consisted in an iterative sequence of the three following steps: cluster formation, dendrogram analysis and classification using the maximum likelihood method. Ecological importance of the classification has been obtained by means of the aggregation of a part of classes based upon the statistics calculated for them within the GIS system with the help of the zonal function out of the following parameters: salinity, depth, mean and maximum orbital velocity at the bottom, temperature differences between warm and cold seasons, solar radiation, and type of sediments. The method proposed here makes it possible to produce high resolution thematic maps of the bottom even with incomplete data cover of the investigated area.

Speciation of heavy metals in marine sediments vs their bioaccumulation by mussels

Total contents and speciation of selected heavy metals, including Al, Fe, Co, Ni, Pb, Zn, Cu, Cr, were measured in sediment samples and mussels Mya arenaria and Astarte borealis collected in the Horsund Fjord off Spitsbergen (Norwegian Sea) and the Bay of Gdansk (Baltic Sea). The investigation aimed at revealing differences in the accumulation pattern of heavy metals in mussels inhabiting sediments characterized by varying metal bioavailability. The contents of metals adsorbed to sediments and associated with iron and manganese hydroxides, which were obtained by sequential extraction, were utilized as a measure of metal bioavailability. The contents of Cd, Pb, Zn, Cu and Cr in mussels collected off Spitsbergen were generally lower than those in mussels from the Baltic Sea. In sediments collected off Spitsbergen the bioavailable fraction represented a small proportion (0–3.7% adsorbed metals and 0–11% associated with metals hydroxides) of total heavy metal contents. In sediments from the Baltic Sea the percentages of metals adsorbed and bound to hydroxides were 1–46% and 1–13%, respectively. The differences in bioavailable metal contents measured in sediments were utilized to explain the different contents of metals in mussels collected in the corresponding sites.

Post‐fledging migration of common murres Uria aalge in the Baltic Sea: management implications

In this study of common murre Uria aalge chicks, at Slora Karlsö in the Baltic Sea (Sweden), we used two data sets to investigate the post‐fledging migration to learn more on potential threats from human activities. Firstly, we radio tracked 12 chicks on average 5.1 h during their first night at sea, after jumping from the breeding cliffs in early July. Their average speed was 1,9 km h‐’and all chicks swam in a similar direction (SW) with a mean bearing of 235°. By searching an area of ca 400 km2 further off the island between two and six days after the radio tracking, we concluded that they did not stop, even temporarily, within 40 km off the island, but had continued the swimming migration. Our second data set was made up by 400 recoveries of ringed chicks. Only those recovered within eight months after fledging (until February) were included. Two birds recovered at the Polish coast in the beginning of August had moved on average 10.7 and 12.3 km day‐’(i.e. 0.45‐0.51 km h‐). In August, all chicks, except one, were found south of Gotland &gt; 70 km away. The average distance to the recovery sites in. August was 253.5 km (n = 11). The pattern of distribution of birds reported in September. October and during the winter period from November to February was about the same as in August. The average direction from the colony lo the recovery sites was S to SW. Important findings from nature management perspective are: 1) our data suggest that the route of the chicks at least partly coincide with ship routes with at least 42000 passages each year. Hence, there is a potential for a great part of the common murre population to get in contact with oil spillage at this stage, notably in the first half of July. 2) From the 400 reported recoveries of ringed chicks we concluded that the most important over wintering areas are around Bornholm and the Bay of Gdansk. Hence, these are the most likely areas for conflicts with the fishery and oil spillage during the winter.