Volume 41 (2012): Issue 4 (December 2012)

Assessing the impact of ionizing radiation on the marine environment requires a well-defined methodology, which includes, among other elements, the analysis of exposure and effects. One of the most important components of the assessment system is the choice of reference organisms specific for the assessed area that fulfill requirements such as radioecological sensitivity, widespread distribution, and amenability to research and monitoring. The following species specific to the southern Baltic Sea that represent diversified ecological niches were proposed as reference organisms. Polysiphonia fucoides was proposed as a representative of macroalgae. Pelagic and benthic fauna were represented by Crangon crangon (crustacean), Saduria entomon (crustacean), Hediste diversicolor (polychaete), and Mytilus trossulus (mollusc). Fish were represented by Clupea harengus (pelagic planctotrophic fish), Gadus morhua (pelagic carnivorous fish), and Platichthys flesus (benthic fish). Activity concentrations of 137Cs were determined in reference biota as well as in seawater, as required for the total dose-rate evaluation, and relevant concentration factors were calculated.

Effects of environmental factors, including acidity, temperature, oxygen, nitrogen, phosphate and total iron content, on the diversity of aquatic mycobiota in lake water were studied in two lakes in Northern Poland in 2005–2007. Fifty four species of fungi and fungus-like organisms were recorded in the sub-surface and benthic of both lakes. There were 36 and 45 species in Lakes Marta and Sitno, respectively. The greatest species diversity was observed with a higher content of oxygen and biogenic compounds in the surface water. Temperature and oxygen content were the most important factors affecting the distribution of mycobiota in lake water.

Chlorination is a common antifouling method adopted by industrial units to minimize the fouling growth on cooling systems. In the present study, the effect of sodium hypochlorite on extracellular polymeric substance (EPS) production, hydrophobicity, cell adhesion and viability of marine bacteria involved in biofilm formation were assessed in laboratory condition. Two bacterial strains, tentatively identified as Alteromonas sp. and Pseudomonas sp. isolated from the surface of seaweeds were used as test organisms for the present study. The bacterial cultures were treated with sodium hypochlorite at 25% of the minimum inhibitory concentration. Results showed considerable variation in the production of EPS, viable counts, hydrophobicity and adhesion ability of bacteria treated with sodium hypochlorite. In general, the present study indicated that chlorination affects some important characteristics involved in the biofilm formation and thereby reduces the adhesion rate on surfaces.

The population dynamics of harmful microalgae was investigated in the semi-enclosed shallow lagoon, Tunis northern lagoon (South Mediterranean), during a 1-year period from January to December 2007. A total number of 16 potentially toxic dinoflagellates were identified. Density of each species was analyzed in time and space and in relation to environmental parameters. Some species such as Alexandrium catenella, A. pseudogonyaulax, A. tamarense, Dinophysis sacculus, Prorocentrum lima, P. minimum and Gonyaulax spinifera developed high cell concentrations, particularly during spring and summer seasons. Other species such as A. insuetum, A. lee, A. minutum, Coolia monotis, D. acuminata, D. caudata, D. fortii, Ostreopsis siamensis and P. concavum were detected in this coastal ecosystem, but they were rare or appeared in very low densities.

Densities of the most abundant species were closely associated with spring and summer conditions, being positively correlated with water temperature and salinity. These species performed well in this lagoon, but the specific species-dependent affinity to each of the environment factors determined which organisms proliferated. The spatial distribution of the abundant species exhibited a marked increase towards the western and southern parts of the lagoon represented by sites C, D and E. Examination of the temporal distribution revealed that the species more prone to bloom are those with extensive spatial distribution and frequent presence throughout the year such as D. sacculus.

Statistical analysis of D. sacculus density dynamics showed a significant difference between summer and winter assemblages. It presented a positive correlation with water temperature and salinity, but it seems to be tolerant to all levels of nutrients.

The structure of the benthic amphipod assemblage and its relationship with soft-bottom characteristics (particle size, organic matter, etc.) of the coastal waters at the depths of 0–5 m at the Dardanelles, including the Turkish Straits System, was studied. A SCUBA diver took benthos and sediment samples seasonally using a quadrate system of 30×30 cm as three transects from the 8 different stations between July 2008 and April 2009. A total of 3007 individuals belonging to 50 species was reported. Among these, Corophium acutum Chevreux, 1908 had the highest dominance value (Di%=22.18) and the lowest dominance value belonged to Dexamine thea Boeck, 1861 (Di%=0.03). The highest positive correlation (rs=0.57, p<0.05) was observed between the gravel content (%) and the abundance (ind. m−2). The highest sand rate (99.59%) in the sediment was found at the Eceabat site. The lowest rate was at the Kepez Harbour station with a value of 73.01%. The highest H′ value (1.53) was recorded at the Eceabat site, and the lowest H′ value (H′=0.95) was recorded at the Gallipoli sampling station.

Macoma balthica is a marine bivalve commonly occurring in the boreal zone. It is one of the most common zoobenthos species in the Baltic Sea, including the Gulf of Gdańsk, and a significant element of the food web. Observations of the infection prevalence in M. balthica from different parts of Gulf of Gdańsk were conducted in 2007-2008, taking into account the water depth. Metacercariae of Gymnophalloides (=Lacunovermis) macomae (prevalence: 89.0%) were found, as well as sporocysts with metacercariae of Parvatrema affinis (prevalence: 1.1%) and unidentified sporocysts with cercariae (prevalence: 1.3%). The most infected clams were found on the shallowest research station (30 m).

A four-year study carried out in a lake with perennial water blooms caused by toxigenic Planktothrix agardhii (Oscillatoriales) and Anabaena lemmermanii, Anabaena flos-aquae, Anabaena spp. and Aphanizomenon issatchenkoi (Nostocales) revealed that the lake-dwelling fish were threatened by simultaneous exposure to intracellular and extracellular microcystins (MCs) as well as anatoxin-a (ANTX). Higher contents of anatoxin-a and microcystins were found in livers than in fish muscles. This is the first report on ANTX accumulation in the common fish, indigenous to European freshwaters during perennial cyanobacterial blooms. Generally, the omnivorous roach (Rutilus rutilus) and Prussian carp (Carassius gibelio) accumulated higher amounts of MCs in their tissues compared to mostly predacious perch (Perca fluviatilis), and similar amounts of ANTX. The long-lasting presence of MCs exceeding the safe levels for consumption was found in fish muscles. ANTX accumulation in fish muscles (up to 30 ng g−1 FW) suggests the probability of its transfer in a food chain.

Eleven physicochemical parameters of data collected from 12 stations in Daya Bay in 2003 were analyzed by multivariate statistical analysis. Cluster analysis (CA) grouped data from 4 seasons into two groups, the northeast and southwest monsoon periods, representing different natural processes. During the northeast monsoon period, principal component analysis (PCA) and CA group the 12 monitoring sites into Cluster DA1 (S1, S2 and S6) and Cluster DA2 (S3-S5 and S7-S12). During the southwest monsoon period, PCA and CA group the 12 monitoring sites into Cluster WB1 (S1, S2, S7, S9 and S11) and Cluster WB2 (S3-S6, S8, S10, S11 and S12). The spatial heterogeneity within the bay was defined by different hydrodynamic conditions and human activities. These results may be valuable for achieving sustainable use of the coastal ecosystems in Daya Bay.

The Mediterranean green crab Carcinus aestuarii Nardo, 1847 (Crustacea, Brachyura, Portunidae) is a common inhabitant of the shallow waters of Homa Lagoon in Izmir Bay, Turkey, in the eastern Mediterranean. Monthly samples were collected in Homa Lagoon from June 2006 to May 2007 using trammel nets, fyke nets, beach seines and fence traps. In total, 608 males and 559 females of C. aestuarii were collected. The highest sex ratio (81–86% females) was recorded between October and December, and in August (58% females). Ovigerous females were obtained only from November to February with the highest ratio of ovigerous females (55%) observed in January 2007. The maturation curve presenting the carapace width showed that 50% of female crabs with the carapace width of 26.84 ±1.58 mm (r= 0.72) were physiologically mature. Regression analyses indicated that the number of eggs was positively correlated with carapace width and wet weight (P < 0.05, in both cases).

The Vistula Lagoon, a brackish water body that offers unique living conditions to aquatic organisms, is an interesting object of hydrobiological investigations. This paper presents a review of biological research conducted on the Vistula Lagoon, from simple floristic and faunistic analyses to satellite-based comprehensive environmental analyses. Changes that occurred in the studied aquatic ecosystem due to human pressure over the last century are discussed. Innovative research technologies determined what measures should be taken to preserve the unique biocenoses in the Vistula Lagoon.