Volume 36 (2007): Issue 4 (December 2007)

Phytoplankton in the littoral zone of the urban Lake Jeziorak Mały (Mazurian Lakeland) were studied between April and October of 2002 and 2003. Five diatom species (Fragilaria delicatissima, Aulacoseira granulata, Fragilaria capucina, Diatoma vulgaris, Fragilaria crotonensis) and one genus (Rhizosolenia sp.), comprising the major proportion of total abundance and biomass of diatoms, were chosen for the study. The relationships between the biomass of these diatoms and water temperature, oxygen content, electrolytic conductivity, orthophosphates, silicon and calcium concentrations were analyzed. The biomass of species F. delicatissima, A. granulata and F. capucina tended to be the highest of the six, which were also associated with the widest temperature range, 10.0°C to 18.7°C. These three species exhibited maximum biomass at the highest orthophosphate concentrations. By contrast, F. crotonensis developed in the narrowest water temperature range, 10.0°C to 13.7°C. The maximum biomass of this species was noted at high silicon and calcium concentrations. The diatoms (except F. capucina and Rhizosolenia sp.) contributed to statistically significant observed reductions in nutrient concentrations during their growth. These results indicate that a range of factors is involved in the productivity and limitation of the studied diatoms, with water temperature being of particular importance.

The Vistula Estuary is a coastal water body boasting free connection with the open sea, where mixing processes of marine and fluvial waters are maintained by local conditions. Based on results from a hydrodynamic model, applied to represent conditions in the year 1994, and using salinity as a tracer, it was found that fluvial water has a tendency to spread westward from the river mouth. This is in contradiction with the dominant wind direction in the region. Model results confirmed field observations of specific hydrological and meteorological conditions required to transport fluvial water northward, towards the Hel Peninsula.

Flounder is the target of directed fisheries in coastal waters and is a bycatch of cod fishing. Flounder were fished in the Baltic region ICES Subdivision 26 (SD 26) by Polish and Soviet fleets until 1991. Since that time political and economic changes have altered the exploitation structure of that area, leading to increased fishing effort and flounder catches. This report, which is based on Polish, Russian and Lithuanian data, presents a review of long term changes in flounder fisheries in SD 26, and describes the current status of flounder exploitation there. The eXtended Survival Analysis (XSA) method was used to assess the stock. The results indicate that the flounder stock in SD 26 is in good condition and that the spawning stock biomass (SSB) is at a consistently high level. However, the estimated mean fishing mortality (F_bar), with reference to Biological Reference Points, indicates that the stock is being exploited too intensely to be sustainable.

The process of ecological succession in marine fouling communities was investigated at two study sites in the Gulf of Gdańsk, Gdynia and Gdańsk. Settlement panels were used as substrata for sessile organisms, and the study lasted 150 days between May and October 2005. Communities were dominated by two species, Balanus improvisus and Mytilus trossulus. The process of succession differed at these two study sites, particularly in the final part of the experiment. Four stages of succession were distinguished at both study sites; at Gdańsk: (1) Biofilm - phase, (2) Green algae - phase, (3) Balanus - phase, (4) Ectocarpaceae - phase; at Gdynia: (1) Biofilm - phase, (2) Balanus - phase, (3) Green algae - phase, (4) Mytilus - phase.

Sediment cores were collected from a number of sites in the Port of Gdansk in 1997 and 1998. The samples were segregated by depth then dried, homogenised and sieved into four grain size fractions (>2.00 mm, 2.00 - 0.063 mm, 0.063 - 0.032 mm, and 0.032 mm) Small-grained sand with a low admixture of silt predominated in all samples, whilst the amount of organic matter and water varied between samples. The 2.00 - 0.063 mm size fraction was the most abundant; and also showed the highest accumulation of trace metals. In the >2.00 mm size fraction the mean concentration of labile forms of copper was 9.06 mg kg^-1 DW, while the concentration of total forms was 12.73 mg kg^-1 DW. The mean concentrations of labile and total forms of zinc in this fraction were 31.79 and 46.27 mg kg^-1 DW, respectively. The widest ranges of concentrations for both labile and total forms of the metals were found in the near-surface sediment layers (0-20 cm). Sediments collected from highly industrialized locations contained the highest concentrations of metals.

Environmental pollution is currently a major concern due to unorganised and increased industrialization and urban development. In the Tamilnadu state of India, on the Bay of Bengal, lies the Ennore estuary, which is an important industrial centre. The main industries in the region include a fertilizer company, refineries, a rubber factory, paint industry and a thermal power station. Investigations into the seasonal pollution impacts on the distribution of various metals in the waters of the Ennore estuary, situated in North Chennai, Tamilnadu, India, and the concentrations of some of the toxic metals in the tissue of the grey mullet, Mugil cephalus L., inhabiting in the same estuary were conducted during the period of April 2004 to March 2006.

The results were compared to those of the Kovalam estuary, which is unpolluted. In the water at one sample site of the Ennore estuary, heavy metal concentrations ranged between: Pb 0.15-0.23, Hg 0.05-0.06, Cd 0.01-0.03, and Cr 3.33-1.093 ppm for summer and monsoon seasons, and were significantly related to the seasonal rains (p<0.01). In contrast, heavy metal concentrations in the Kovalam estuary ranged between: Pb 0.043-0.039, Hg non-detectable-0.001, Cd 0.01-0.098, and Cr 0.063-0.052 ppm, and were not significantly related to the rainy season. The metal concentrations found in the muscle tissues of Mugil cephalus L., at the same site on the Ennore estuary were: Fe 11.06 ±0.29, Zn 1.67 ±0.14, Cr 2.98 ±0.15, and Pb 1.26 ±0.11 ppm, which were also significantly related to season (p<0.01). The metal concentrations in fish inhabiting the Kovalam estuary were: Fe 2.17 ±0.15, Zn 0.42 ±0.05, Cr 0.63 ±0.04, and Pb 0.31 ±0.04, and showed no significant seasonal difference. The highest metal concentrations found in the tissues of the Ennore estuary fish which lead to the oxidative stress and shorten the lifespan of the fish are postulated to primarily result from anthropogenic activities and effluent discharge from the local industrial activities.

In the Baltic modelling research, assimilation techniques were developed with advance. They were concerned to model assimilated basic parameters and observed them directly. In present paper, the most important was the assimilation of surface information and its projection deep into temperature and salinity fields. In oceanic investigations altimetry viewed from satellite was the sea level changes projected far inside and predetermined surface-to-subsurface correlations. To obtain improved modelled hydrophysical fields, sea level variations measured at coastal gauges and efficient data assimilation were taken into account. A data assimilation algorithm has been developed and used in conjunction with a three-dimensional baroclinic model of the Baltic Sea. It was based on a time and space weighted nudging technique. The sea level data were inserted continuously by updating the model solution every time step. Several sensitivity experiments with different values of time and spatial weighting scales were performed. In first series of experiments, only sea level data (SL) were assimilated. In the next simulations, seawater temperature (SWT) and seawater salinity (SWS) related directly to SL were assimilated. To evaluate the effectiveness of the assimilation scheme, modelled sea level series and vertical profiles of seawater temperature and salinity in selected coastal gauges in the Gdansk Basin were examined. Evidently low but statistically essential correlation coefficients indicated nonlinear character of vertical mixing and transfer processes. Decreasing errors obtained while comparing the model results to a control case without assimilation confirmed a real transfer of surface information deep and usefulness of such approach in modelling.

During investigations of the Baltic Sea basin significant differences have become manifest in the distribution of certain chemical elements in different chains of the geo (-eco) system (soils, river, lagoon and marine sediments). This paper presents data on the quantitative relationships of elements resulting from interactions of natural sedimentation processes and the possible human impact on the sediments from two port areas. The total (T), lithogenic (LG; stable) and hydrogenic (HG; mobile, reactive) migration forms of Zn, Cr, Cd, Cu, Pb and Ni were analysed. The HG component comprises that pool of the elements contained in readily degrading minerals; increases in this form potentially being an indicator of adverse human impacts. The distribution of total forms depends on the quantity of the sediment fraction with grain size < 0.063 mm (fr. < 0.063 mm) and on the concentration of organic content (C_org).

With increasing sediment depth, the concentration of elements decreases sharply, although HG concentrations were seen to increase on several occasions. One explanation for such findings is the mineralisation and decomposition of metals from the remnants of biological activities of organisms (pellets, globules) into the sediments. Element concentrations in the natural sedimentation zone (NSZ) of the marine-influenced North Port at Gdańsk are less than in the NSZ and technogenic sedimentation zone (TSZ) of the riverine part of the port of Gdańsk. The ratios between HG, LG and T in the two sedimentation zones are different for different elements, but are always higher in the TSZ than in the NSZ. Multi-site analyses of the port basins allowed NSZ and TSZ to be distinguished. The TSZ is typified by anomalous concentrations of elements, the specific distribution of their migration forms, the semi-stagnant conditions prevailing there and the proximity of human impact sources. The data presented in this paper indicate that the concentrations of only some of the elements in the TSZ sediments of the ports of Klaipėda and Gdańsk exceed the permitted norms for spoil dredged from port basins. By no means can the total load of elements contained in the spoil dumped at sea be treated as an indicator of marine pollution. For an objective assessment of the real pollution threat to port environments, detailed investigations of the various migration forms of chemical elements need to be carried out, and previously established levels revised.

Research into the suitability of Microtox® for the evaluation of toxicity of surface waters and bottom sediments in Poland was conducted. Water bodies of various pollution levels were tested, including the Odra River and its tributaries, the Lower Vistula River, the Kashubian Lake District and the Gulf of Gdańsk, using a Microtox® Model 500 analyser (Microbics Corporation, USA). The majority of tested surface water samples were found to be apparently non-toxic. However, 75% of the bottom sediment samples were found to be highly toxic (EC50>2%). These results indicate that the Microtox® test is suitable for evaluating the toxicity of bottom sediments, in which pollutants tend to accumulate. It seems, however, that Microtox® lacks the sensitivity to be of use in analyzing water quality. The relationship between the toxicity of analysed sediments and their organic content was examined.

The present paper reports on the occurrence of the epibiotic ciliates of the family Folliculinidae Dons on the American crayfish Orconectes limosus (Raf., 1817). This is the first report of folliculinid ciliates from coastal waters of Puck Bay observed on animal substrata.