FEEDING OF THE INVASIVE ROUND GOBY Neogobius melanostomus (Perciformes: Gobiidae) IN THE SOUTH-EASTERN BALTIC

The feeding of the Ponto-Caspian invasive round goby Neogobius melanostomus in the coastal zone of the Baltic Sea near the Curonian Spit, in the Vistula Lagoon and in the eastern part of the Gdansk Bay has been studied. The round goby in coastal waters prefers biotopes with various shelters - boulders, large pebbles, etc. In the diet of the round goby, there is a significant proportion of fouling organisms inhabiting these objects. If fouling organisms are absent for some reason, the goby switches to other types of prey: molluscs, free-living crustaceans, insect larvae and other groups of benthic and nektobenthic organisms. There is a connection between the food spectrum and the size of the round goby: large individuals consume larger prey. The round goby implements a food strategy, which consists in the fact that all organisms that are available territorially and in size are used for food. Such food plasticity is one of the reasons for the wide expansion of this species outside the native range.

The impact of sediment, fresh and marine water on the concentration of chemical elements in water of the ice-covered lagoon

The common use of chemical elements by man has been contributing to their extraction for centuries. As a consequence, they have been directly or indirectly introduced into the biogeochemical cycle. In the framework of many conventions, mining and processing of elements are currently subject to many restrictions. However, their large load that has already been deposited in the soil and bottom sediments can be remobilised and enter the food chain. The identification of factors favouring this process is very important, especially during the period of adopting new legal regulations on limiting the emission of pollutants. It became possible in February 2018 during the persistence of ice cover on the lagoon’s surface. This allowed observation of processes, the effect of which in the absence of ice is blurred by wind mixing water. Therefore, an investigation of sources of 25 elements in a lagoon of the southern Baltic has been undertaken, based on the example of the Vistula Lagoon. The results point to the remobilisation of chemical elements (including the toxic ones) from land and bottom sediments, where they have been deposited for decades. These processes led to the accumulation of metals in certain areas of the lagoon. It may result in their uptake and accumulation in the benthic organisms inhabiting the lagoon and further transfer in the food chain. It is of major importance as the lagoons in the southern Baltic fulfil many essential functions in the scope of tourism, economy, and fishery. Thanks to restrictions on the quality of wastewater and the emission of pollutants, it has been noticed a substantial “purifying” effect of rivers, too.

Analysis of the Water Level Variation in the Polish Part of the Vistula Lagoon (Baltic Sea) and Estimation of Water Inflow and Outflow Transport through the Strait of Baltiysk in the Years 2008–2017

The Vistula Lagoon is located in both Poland and Russia along the southern coast of the Baltic Sea. It is connected to the Baltic Sea in the Russian part by the Strait of Baltiysk. The purpose of the paper is to identify the dominant factors underlying the water level variation mechanism at Tolkmicko in the Vistula Lagoon, revealed by a statistical analysis of the measured data and a discussion on the inflow and outflow transport variation through the strait, estimated by numerical modeling. Seawater transport is exceptionally valuable in terms of the hydrological water balance in the lagoon. Historical research on the hydrology of the lagoon shows that the water exchange in the lagoon is quite complex due to the presence of several different sources of water balance, such as seawater inflow, river inflow, groundwater inflow, precipitation, and evaporation. Unfortunately, there are no current data on seawater inflow and outflow through the Strait of Baltiysk due to the lack of continuous flow measurements in the strait. A novelty of the current work is an in-depth statistical analysis of the water level variation in the Polish part of the lagoon over a long time period and an estimation of water transport through the Strait of Baltiysk by use of a numerical model. The model reproduces well the water level variation responding to variations in the sea level outside the lagoon and the wind action over the lagoon. The years 2008–2017 were chosen as the analysis period. A two-dimensional free surface shallow water numerical model of the lagoon was adapted to simulate the water level variation in view of the wind over the lagoon and the sea level variation at one open boundary. Finally, it was concluded that the water level variation on the Polish side of the Vistula Lagoon is dominated by two factors: the water level in the Gulf of Gdańsk and the wind over the lagoon. The average annual marine water inflow into the Vistula Lagoon was estimated to be equal to 15.87 km3.

Development Prospects of Tourist Passenger Shipping in the Polish Part of the Vistula Lagoon

The Vistula Lagoon is a cross-border area with high natural values and a developing market of tourist services. Passenger shipping is an important part of local tourism, but ship owners are insufficiently involved in planning processes and their views on creating shipping development are underrepresented. The article aims to compare the vision of the development of passenger shipping in the Polish part of the Vistula Lagoon between local governments creating the spatial policy and ship owners offering transport services. We have made an attempt to verify the development prospects. The collation of these visions was based primarily on the qualitative analysis of the content of planning and strategic documents (desk research method) and a survey conducted among all six ship owners. Thanks to the comparative analysis, it was possible to show similarities and differences and to indicate recommendations. The paper presents review of the available literature on the subject, thanks to which the research area was identified as unique in Europe. On the one hand, it is a valuable natural area, which is an important tourist destination, on the other hand, there are organizational and infrastructural limitations in meeting the needs of tourists. Then, field research was conducted, unpublished materials were collected, and surveys were conducted with the operators of passenger ships operating in the Vistula Lagoon. The performed analyses allowed for the formulation of conclusions and recommendations. Similarities in the directions of promoting tourism in the region, improving the quality of infrastructure, eliminating obstacles in international traffic and discrepancies in the co-financing of ship owners’ activities by local governments, shaping the future transport offer or the construction of the Vistula Spit canal are identified. Economic calculation, particularly vital for the private sector (ship owners), is an important criterion for verifying the assumed goals.

Evolution of sedimentation in the Vistula Lagoon of the Baltic Sea due to anthropogenic impact

The work pursued basic objectives: to study the structure of the sedimentary strata, identify the sediment units corresponding to specific sedimentation stages of the late Holocene and evaluate the factors that influenced their formation in the Vistula Lagoon. For the achievement of the goals, well-known methods were used. The thickness of the silt deposits was measured by a hand drill. The grain size analysis of bottom sediments was determined by the mass content of particles of various sizes as a percentage of the test sample mass. The content of the total amount of organic matter in the bottom sediments and the mass loss during calcination was determined by the weight method, the determination of the mineral vivianite was carried out by standard methods accepted in geology. The Research results showed that in the lower part of the cores, organic-rich silts of olive shades are common, formed under the influence of river runoff. The sediment composition in the upper part of the cores is sharply different due to an anthropogenic factor – artificial river runoff regulation. Instead of silty sediments, the lagoon accumulated poorly consolidated, dark gray fine sand and siltstone sediments with small organic matter.

e-Navigating in highly-constrained waters: a case study of the Vistula Lagoon

In recent years the transition of marine navigation to the digital era has been gaining momentum. Implementation of e-Navigation solutions varies from country to country in terms of their priorities, goals, levels and effects. Maritime authorities in Poland have been setting the pace in this transition process, not only in Poland but also in general as a global solution. The most recent example is the planned deployment of a variety of e-Navigation tools in the Vistula Lagoon: from GNSS-RTK Ground-Based Augmentation System, to virtual and synthetic aids to navigation, high-resolution bathymetry and advanced navigational software for piloting. The major objectives of this paper are, first, to summarise recent dynamics in the e-Navigation field, and second, to present a practical implementation of the e-Navigation concept in the Vistula Lagoon area.