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1

Study of ice cover impact on hydrodynamic processes in the Curonian Lagoon through numerical modeling

Idzelytė Rasa, Mėžinė Jovita, Zemlys Petras, Umgiesser Georg

Oceanologia

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2020

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No. 62 (4PA)

428--442

EN

In this study, we present an analysis of the hydrodynamic processes under ice cover in the largest lagoon in Europe – the Curonian Lagoon. By applying a finite element numerical modelling system (SHYFEM) and remote sensing ice cover data, the residual circulation, water fluxes through specific areas of the lagoon, saltwater intrusions, and water residence time (WRT) were investigated. The results, taken over an 11 year period, show that ice cover affects the circulation patterns in the lagoon by forming and shifting different gyre systems. Different circulation patterns are observed throughout all the meteorological seasons of the year. Since ice decreases circulation, water fluxes also decrease, especially in a cross-section in the middle of the lagoon, where the ice-cover suppressed wind-stress has a higher impact on the water movement rather than it has in the north. The presence of ice cover also decreases the salinity of the water in the northern part of the lagoon. In general, the salinity in the water column averaged over different periods is vertically uniform, however, a slight increase of salt concentration can be observed at the bottom layers in the Klaipėda Strait, where the difference of >1 PSU between bottom and top layers shows up on average 130 hours per year. The ice cover also decreases the saltwater intrusions into the lagoon by nearly 14 days per year. The increase of WRT is most prominent after long ice cover periods, away from the river inlets, especially in the southern part of the lagoon, where without the help of the wind action, water takes a longer time to renew than in the northern part.

2

Impact of climate change on the Curonian Lagoon water balance components, salinity and water temperature in the 21st century

Jakimavičius D., Kriaučiūnienė J., Šarauskienė D.

Oceanologia

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2018

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No. 60 (3)

378--389

EN

The Curonian Lagoon is a shallow water body connected to the Baltic Sea by a narrow navigable strait, which enables an exchange of water of different salinity. The projected climate change together with the peculiarities of mixing water will undoubtedly alter hydrological regime of this lagoon. The study uses three climate model outputs under four RCP scenarios, four sea level rise scenarios and hydrological modelling in order to project the extent to which water balance components, salinity and temperature may change in the future. In order to simulate river inflow, the Nemunas River hydrological model was created using HBV software. In general, the changes of the lagoon water balance components, salinity and temperature are expected to be more significant in 2081-2100 than in 2016-2035. It was estimated that in the reference period (1986-2005) the river inflow was 22.1 km3, inflow from the sea was 6.8 km3, salinity (at Juodkrantė) was 1.2 ppt and average water temperature of the lagoon was 9.2°C. It was projected that in 2081-2100 the river inflow may change from 22.1 km3 (RCP2.6) to 15.9 km3 (RCP8.5), whereas inflow from the sea is expected to vary from 8.5 km3 (RCP2.6) to 11.0 km3 (RCP8.5). The lagoon salinity at Juodkrantė is likely to grow from 1.4 ppt (RCP2.6) to 2.6 ppt (RCP8.5) by the end of the century due to global sea level rise and river inflow decrease. The lagoon water temperature is projected to increase by 2-6°C by the year 2100.

3

Distribution of metals and extent of contamination in sediments from the south-eastern Baltic Sea (Lithuanian zone)

Remeikaitė-Nikienė N., Garnaga-Budrė G., Lujanienė G., Jokšas K., Stankevičius A., Malejevas V., Barisevičiūtė R.

Oceanologia

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2018

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No. 60 (2)

193--206

EN

The distribution of metals (Pb, Cu, Cd, Ni, Cr, Zn) in surface sediments and the potential pollution sources in the south-eastern part (SE) of the Baltic Sea (Lithuanian zone) were investigated in relation to the environmental characteristics (amount of fine-grained particles, TOC content in sediments, origin of sedimentary organic matter, salinity, water depth) in 2011-2014. The higher metal concentrations were measured in sediments of the Curonian Lagoon and in the open waters. An approach using various environmental indices (enrichment factor EF, geoaccumulation index Igeo and contamination factor CF) was used to quantitatively assess a contamination degree. The principal component analysis (PCA) was applied in order to further scrutinize pollution from metal sources. The values of the contamination indices showed no/very low sediment contamination with Ni and Cr, minor-moderate contamination with Cu, Zn and Pb and moderate-considerable pollution with Cd. The strong relationships among metals suggested their similar distribution pattern and a combination of natural and anthropogenic sources. The higher metal concentrations coincided with an increasing amount of fine-grained fraction and organic carbon. In the territorial waters, the distribution of elements was related to the water depth. In addition, the binding of metals with insoluble iron sulphides might explain their high concentrations at the most remote and deepest stations.

4

Microorganisms associated with charophytes under different salinity conditions

Kataržytė M., Vaičiūtė D., Bučas M., Gyraitė G., Petkuvienė J.

Oceanologia

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2017

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No. 59 (2)

177--186

EN

Microorganisms associated with aquatic macrophytes can in various ways interact with a plant and influence its activity and vice versa. A low-salinity intrusion into freshwater environment can affect plant-microorganism interactions. In this study, effects of different salinity conditions on the abundance and community composition of associated microorganisms with charophytes in the Curonian Lagoon were assessed. From the results, we found that short term salinity changes affected the abundance of bacteria and fungi associated with charophytes, whereas no response was reflected in the taxa composition of fungi, showing that other factors could be of more importance. The increased fungi abundances and different fungi composition in August in comparison to June was probably related to senescence process of aquatic vegetation. 8 fungi taxa were isolated and identified in association with charophytes, while higher diversity was revealed by DGGE technique.

5

Curonian Lagoon drainage basin modelling and assessment of climate change impact

Čerkasova N., Ertürk A., Zemlys P., Denisov V., Umgiesser G.

Oceanologia

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2016

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No. 58 (2)

90--102

EN

The Curonian Lagoon, which is the largest European coastal lagoon with a surface area of 1578 km2 and a drainage area of 100,458 km2, is facing a severe eutrophication problem. With its increasing water management difficulties, the need for a sophisticated hydrological model of the Curonian Lagoon's drainage area arose, in order to assess possible changes resulting from local and global processes. In this study, we developed and calibrated a sophisticated hydrological model with the required accuracy, as an initial step for the future development of a modelling framework that aims to correctly predict the movement of pesticides, sediments or nutrients, and to evaluate water-management practices. The Soil and Water Assessment Tool was used to implement a model of the study area and to assess the impact of climate-change scenarios on the run-off of the Nemunas River and the Minija River, which are located in the Curonian Lagoons drainage basin. The models calibration and validation were performed using monthly streamflow data, and evaluated using the coefficient of determination (R2) and the Nash-Sutcliffe model efficiency coefficient (NSE). The calculated values of the R2 and NSE for the Nemunas and Minija Rivers stations were 0.81 and 0.79 for the calibration, and 0.679 and 0.602 for the validation period. Two potential climate-change scenarios were developed within the general patterns of near-term climate projections, as defined by the Intergovernmental Panel on Climate Change Fifth Assessment Report: both pessimistic (substantial changes in precipitation and temperature) and optimistic (insubstantial changes in precipitation and temperature). Both simulations produce similar general patterns in river-discharge change: a strong increase (up to 22%) in the winter months, especially in February, a decrease during the spring (up to 10%) and summer (up to 18%), and a slight increase during the autumn (up to 10%).

6

Bioaccumulation of microcystins in invasive bivalves: a case study from the boreal lagoon ecosystem

Paldavičienė A., Zaiko A., Mazur-Marzec H., Razinkovas-Baziukas A.

Oceanologia

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2015

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No. 57 (1)

93--101

EN

In the current study we present the first report on the bioaccumulation of microcystins (MC) in zebra mussel Dreissena polymorpha from the eutrophic brackish water Curonian Lagoon. The bioaccumulation capacity was related to age structure of mussels and ambient environmental conditions. We also discuss the relevant implications of these findings for biomonitoring of toxic cyanobacteria blooms in the Curonian Lagoon and potential consequences for D. polymorpha cultivation activities considered for the futures as remediation measure. Samples for the analysis were collected twice per year, in June and September, in 2006, 2007 and 2008, from two sites within the littoral zone of the lagoon. The highest microcystin concentrations were measured in mussels larger than 30 mm length and sampled in 2006 (when a severe toxic cyanobacteria bloom occurred). In the following years, a consistent reduction in bioaccumulated MC concentration was noticed. However, certain amount of microcystin was recorded in mussel tissues in 2007 and 2008, when no cyanotoxins were reported in the phytoplankton. Considering high depuration rates and presence of cyanotoxins in the bottom sediments well after the recorded toxic blooms, we assume mechanism of secondary contamination when microcystin residuals could be uptaken by mussels with resuspended sediment particles.

7

Inventory of the taxonomical composition of the plankton ciliates in the Curonian Lagoon (SE Baltic Sea)

Griniene E., Mažeikaite S., Gasiunaite Z.R.

Oceanological and Hydrobiological Studies

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2011

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Vol. 40, No.4

86-95

EN

Species composition of plankton ciliates was studied in the Curonian Lagoon in 2007-2008 and compared to long term investigations dating back to the 1980th. In total, 152 taxa were identified at the level of species or genera. More species (76 species/higher taxa) was found in the estuarine part of the Lagoon due to temporally unstable salinity and the presence of both freshwater and brackish/marine species. Some of the brackish/marine species: Tintinnopsis baltica, Tintinnopsis kofoidi, Cothurnia maritima, Lohmaniella oviformis, Lohmaniella spiralis and Helicostomella subulatum were recorded for the first time in the lagoon. The ciliate community at the freshwater sites was less diverse, containing 63 species/higher taxa in the central stagnant part of the Lagoon and 47 – in the Nemunas River avandelta. The comparison of present and past studies revealed that the use of a single live-counting method could lead to underestimation of small nanociliate species, whereas examination of Lugol fixed material provides relatively poor taxonomic information.

8

Morphology and distribution of phage-like particles in a eutrophic boreal lagoon

Sulcius S., Staniulis J., Paškauskas R.

Oceanologia

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2011

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No. 53 (2)

587-603

EN

In this paper we present the results of direct observations of the morphology and size of phage-like particles by means of transmission electron microscopy (TEM) as a function of their spatial distribution in the shallow highly productive Curonian Lagoon of the Baltic Sea. In total, 26 morphologically different forms of phage-like particles were found. Different trends of distribution in terms of abundance, size and shape of virus-like particles were demonstrated. The total abundance of viruses varied from 1.91×107 ml-1 to 5.06×107,/sup. ml-1. The virus to bacteria ratio (VBR) changed from 15.6 to 49 and was negatively associated with total bacterial numbers (r = -0.60; p < 0.05). The phages of family Myoviridae were the most diverse and were dominant at all stations.

9

Toxic cyanobacteria blooms in the Lithuanian part of the Curonian Lagoon

Paldavičiene A., Mazur-Marzec H., Razinkovas A.

Oceanologia

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2009

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No. 51 (2)

203-216

EN

The phenomenon of cyanobacteria (blue-green algae) blooms in the Baltic and the surrounding freshwater bodies has been known for several decades. The presence of cyanobacterial toxic metabolites in the Curonian Lagoon has been investigated and demonstrated for the first time in this work (2006-2007). Microcystis aeruginosa was the most common and widely distributed species in the 2006 blooms. Nodularia spumigena was present in the northern part of the Curonian Lagoon, following the intrusion of brackish water from the Baltic Sea; this is the first time that this nodularin-(NOD)-producing cyanobacterium has been recorded in the lagoon. With the aid of high-performance liquid chromatography (HPLC), four microcystins (MC-LR, MC-RR, MC-LY, MC-YR) and nodularin were detected in 2006. The presence of these cyanobacterial hepatotoxic cyclic peptides was additionally confirmed by enzyme-linked immunosorbent assay (ELISA) and protein phosphatase inhibition assay (PP1). Microcystin-LR, the most frequent of them, was present in every sample at quite high concentrations (from <0.1 to 134.2 žg dm-3). In 2007, no cyanobacterial bloom was recorded and cyanotoxins were detected in only 4% of the investigated samples. A comparably high concentration of nodularin was detected in the northern part of the Curonian Lagoon. In one sample dimethylated MC-RR was also detected (concentration 7.5 žg dm-3). full, complete article (PDF - compatibile with Acrobat 4.0), 289.5 kB

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(137)Cs activity distribution in the Lithuanian coastal waters of the Baltic Sea

Davuliene L., Tarasiuk N., Spirkauskaite N., Trinkunas G., Valkunas L.

Oceanologia

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2007

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No. 49 (1)

71-90

EN

The main (137)Cs accumulation zone in the study area was found to be located at depths below the 50-metre isobath, i.e. below the layer of hydrodynamic activity. In coastal waters not influenced by the fresh water discharge from the Curonian Lagoon, (137)Cs occurs mostly in soluble form. The particulate 137Cs activity concentration in the marine area affected by Curonian Lagoon water can make up 10% of the total (137)Cs activity concentration. The circulation model was developed to assess the distribution of artificial radionuclides in Lithuanian territorial waters. The model was validated on the basis of data acquired during the measurement campaign in the Lithuanian part of the Baltic Sea and the Curonian Lagoon in the years 1999-2001. The model enables the (137)Cs activity concentration to be simulated as a passive admixture (error within c. 15%).

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Tolerance of Paramysis lacustris and Limnomysis benedeni (Crustacea, Mysida) to sudden salinity changes: implications for ballast water treatment

Ovčarenko I., Audzijonyte A., Gasiunaite Z.R.

Oceanologia

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2006

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No. 48 (S)

231-242

EN

In order to draw implications for ballast water management, we tested the tolerance of two Ponto-Caspian mysid species Paramysis lacustris and Limnomysis benedeni to sudden salinity changes. The naturally stenohaline P. lacustris was more susceptible to higher salinities; its mortality rate at 19 PSU was 60%, whereas exposure to 23 PSU was 100% lethal. The euryhaline L. benedeni survived in salinities of up to 19 PSU, but experienced 100% mortality at 34 PSU. The return of both mysid species to fresh water after the 24 h exposure to higher salinities did not prevent further mortality. Considering the rather high short-term salinity tolerance of both species, a salinity of at least 30 PSU should be used as an appropriate biocide.

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Impact of invasive benthic crustaceans on the resuspension of bottom sediments : an experimental study

Zaiko A., Olenin S.

Oceanological and Hydrobiological Studies

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2004

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Vol. 33, No. 3

99--110

EN

The resuspension process caused by the burrowing activity of three Ponto-Caspian amphipod species (Pontogammarus robustoides, P. crassus and Chaetogammarus ischus) introduced to the Curonian Lagoon, Baltic Sea, was studied in a laboratory. The experimental set-up included aquaria with three types of bottom sediments: 1) sand; 2) sand with pebbles; 3) sand with stones up to 30 cm in diameter. The experimental aquaria contained amphipods in numbers that mimicked their density in situ, while control aquaria contained no animals. Water was sampled from three different layers (1, 5, and 9 cm above the sediment surface) from experimental and control aquaria and analyzed with a spectrophotometer at a wavelength of 660 nm in order to estimate the density of suspended material. The burrowing activity of the amphipods in all sediment types increased the amount of suspended material throughout the studied water layer (10 cm). The most visible effect was detected above the sandy bottom with large stones, the least – above the sandypebble bottom. The conclusion was drawn that the invasive burrowing amphipods can increase the resuspension of bottom sediments in invaded ecosystems.