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.

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.

The Fight for Free Navigation. Construction of the Channel by the Vistula Spit as Part of the Political Struggle with the Russian Federation

As a consequence of Stalin’s decision, the Vistula Lagoon was divided between Poland and the Soviet Union. Since the Soviet fleet created a naval base in Bałtisko, from 1945 the possibility of using the waterway through the Bay by Poland was practically excluded. The Soviet side allowed iPoland to use the Gulf outlet only to a small extent. In practice, this meant the destruction of the seaport in Elbląg, but also radically limited the possibilities of economic development of this part of Poland, which for many centuries operated on the basis of the Polish economy. After 1989, the Russian side made it even more impossible for the Polish side to use transport routes through the Bay. Ultimately, Poland decided to build a canal through the Vistula Spit. This channel is to enable the revitalization of the port in Elbląg, but also the northern areas of Poland. The article presents the arguments of the Polish side, including economic ones, justifying the implementation of this undertaking.

Hydrodynamic Model of the New Waterway Through the Vistula Spit

The decision to build a new waterway (strait) in the Polish part of the Vistula Spit was made in 2017. The new connection between the Gulf of Gdańsk and the Vistula Lagoon is planned as an artificial navigable channel with a lock and a small port. During storm surges and wind tides in the gulf or in the lagoon, sluicing will be required for vessels to tackle the Vistula Spit. This procedure does not require significant water flow through the channel in normal conditions. However, in the case of a lock failure or in the case of controlled opening of the gate to increase water exchange in the lagoon or to reduce flood risk in the Vistula Lagoon, high flow rates may occur in the navigable channel and in the neighboring port basin. In order to inves-tigate the hydraulic conditions in such extraordinary situations, numerical modeling of the hydrodynamics during water damming in the gulf or in the lagoon is performed. To analyze the hydrodynamics of the artificial connection between the sea and the lagoon during periods of high water stages, mathematical modeling is required. This paper presents the shallow water equations (SWE) model adapted to simulate the flow through the port basin and the navigable channel. The calcula-tions allowed the relation between the water head and the capacity of the navigable channel to be found, as well as to analyze circulations which may occur in the port basin.