Volume 40 (2011): Edizione 3 (September 2011)

137Cs activity concentrations were determined in macrophytes and macrozoobenthic organisms from the southern Baltic Sea. Cesium isotope content was analysed in macroalgae species (green, red and brown algae representatives) and in some species of vascular plants. The analyzed macroinvertebrate organisms included bivalves and a crustacean.

Concentration factors (CF) were calculated using the determined 137Cs concentration in the flora and fauna organisms against that in seawater, and the bioaccumulative properties were compared. The study pointed out that the most important factors in the cesium bioaccumulation process occurring in plants are related to morphology. The highest CF values were obtained in algae Polysiphonia fucoides, Ectocarpus siliculosus and Cladophora glomerata. Decidedly lower CF values were observed in the vascular plants and macrozoobenthos representatives.

The antioxidant system effects of Kandelia candel were investigated under four different levels of PAH stress. The activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), the responses to the change of malondialdehyde (MDA) contents and the accumulation of proline in K. candel were determined. Our results suggested that the activities of SOD, CAT, POD increased significantly in leaves and roots of K. candel (p≤0.05) with the increase of the external PAH concentrations, while in stems, the activities of these antioxidant enzymes were all significantly inhibited (p≤0.01). We also observed an increase of MDA in leaves, stems and roots, and an obvious correlation between MDA content and PAH concentrations in three locations, which showed that the change of MDA content could be used as a biomarker of K. candel under PAH stress. The proline content was found remarkably enhanced in leaves, stems and roots. However, a significant inverse correlation was observed between the proline content and SOD (r=−0.99, p≤0.01), POD (r=−0.95, p≤0.05) activities in stems. This study suggested that the antioxidative system of K. candel has an obvious organ-dependent feature when exposed to PAH contamination as revealed by discriminant analysis (DA).

This paper presents data on the physico-chemical characteristics of lake water from May to November, the period without ice cover. Chlorophyll a was monitored over two years from May to November (2006 and 2007). Water was sampled at five locations in the lake’s littoral zone. The following parameters were investigated: temperature, dissolved oxygen, oxygen saturation, pH, total dissolved solid (TDS), Secchi depth (transparency), turbidity, suspended matter, conductivity, total hardness, alkalinity (bicarbonates), acidity, concentrations of nitrite (NO2 −), nitrate (NO3 −), ammonium (NH4 +), total nitrogen (TN), sulphate (SO4 2−), total iron (Fe), silica (SiO2), phosphate (PO4 3−), total phosphorous (TP) and chlorophyll a. Data were statistically analyzed.

The vertical distribution of zooplankton was examined in Lough Derg, Ireland. Zooplankton was collected at one location every 2 m from the surface to the bottom during 24 hours at four-hour intervals. Zooplankton was identified to the species level and its density was calculated for each taxon, depth and hour. We recorded 9 rotifer, 3 copepod, and 4 cladoceran species. The highest total zooplankton density (rotifers, copepods, cladocerans, mysids and zebra mussel larvae) was recorded at 3 a.m. Rotifers preferred mainly a depth from 0 to 8 m, while copepods and cladocerans were observed within the whole water column during a 24 hour observation. It was a different pattern of diurnal migration than that Southern and Gardiner (1932) received, though they didn’t study rotifers. Probably food concentration and/or predators, or other environmental factors could influence the diel vertical migration of zooplankton from Loug Derg.

Zooplankton vertical migration was described in four high altitude lakes in Gran Paradiso National Park (Northern Italy) during 2008 summertime. The authors succeeded in describing the vertical distribution of 6 species: diel vertical migrations were observed in the case of adult crustacean species (Cyclops gr. abyssorum, Arctodiaptomus alpinus and Daphnia gr. longispina), whereas the remaining rotifer species (Keratella quadrata, Polyarthra gr. dolichoptera and Synchaeta gr. stylata-pectinata) and naupliar stages of copepods did not undergo migrations. Migratory behavior of Daphnia gr. longispina and Cyclops gr. abyssorum was influenced by the size of individuals, especially larger individuals use to migrate deeper during the day compared to the smaller conspecific. This study provides new evidences of zooplankton vertical migration in never-stocked lakes and highlights the need to consider the zooplankton migration as result of multiple causal factors.

Comparative significance and synchronicity of morphological and photosynthetic adjustments of Potamogeton perfoliatus to shore-specific environments were examined on plants growing at the maximum depth of colonisation of the northern and southern shores of Lake Balaton. The shore-specific environments did not affect photophysiological parameters: the photosynthesis of plants on both shores was high, coupled with low respiration and compensation irradiances. In contrast, morphological and habitual differences between the shores were significant: plants of the shady, northern shore had lighter, but larger leaves, and longer internodes concentrated in the apex of the plants. Thus, photophysiological variability of Potamogeton does not follow its morphological differentiation.

The main aim of the present study was to determine the effect of low salinity conditions (3 PSU and 7 PSU) on the hatching success, growth and mortality of Orconectes limosus. The results revealed that berried females survived exposure to salinities of 3 PSU and 7 PSU whilst incubating their eggs. The reproductive success reached 100% at both salinities. The length increment of young crayfish per molt was larger at 7 PSU than at 3 PSU — but their condition was affected by higher salinity. The mortality among juveniles reached approximately 50% within 5 weeks of hatching at both salinities.

We have quantified the relative growth of the merus and the propodus & carpus of walking legs of an adult of Eriocheir sinensis against the carapace width by fitting the major axis lines. Different lines have been fitted to data relative to male and female individuals. Slope and elevation tests have been performed to investigate sexual dimorphism. Isometry tests have been used to classify the relative growth of each part of the legs against the carapace width as isometric or allometric.

All the slope tests have not rejected the null hypothesis of a common slope for the major axes fitted to male data and to female data. However, all the elevation tests have rejected the null hypothesis of a common elevation; so sexual dimorphism was detected for all measured leg parts. The isometry tests have rejected the null hypothesis of isometry only for the merus of the first (left and right) legs of male individuals. All the other isometry tests have not rejected the null hypothesis of isometry. So the relative growth of all the measured leg parts, but the merus of the first (left and right) legs of males, against the carapace width was isometric both for males and for females.

Biomass and generic diversity of heterotrophic protists (protozoa) were studied in the near-bottom zone at five stations located in the inner Gulf of Gdańsk and in offshore waters during June 2002. The highest protozoan biomass was observed in the inner Gulf of Gdańsk and close to the mouth of the Vistula River. Protozoan biomass decreased offshore. In well-oxygenated waters heterotrophic flagellates constituted 39–51%, of the protozoan biomass, ciliates constituted 18–25%, and heterotrophic dinoflagellates 29–39% of the protozoan biomass. These findings confirmed previous studies that showed that a high abundance of heterotrophic dinoflagellates is a distinct feature of the Gulf of Gdańsk. At one station located in the Gdańsk Deep, where the near-bottom zone was anoxic, the contribution of heterotrophic flagellates decreased to 18% and ciliates’ share increased to 82% of the protozoan biomass. No dinoflagellates were observed in the anoxic zone.

The potential capability to decompose macromolecular compounds was confirmed in heterotrophic bacteria isolated from two sandy beaches located on the southern Baltic coast. Proteolytic bacteria were the most numerous group, whereas lipolytic organisms were rare among bacteria inhabiting the studied beaches. All studied physiological groups of bacteria were considerably more numerous in the sand of the beach subject to stronger anthropopressure. The differences in bacteriological parameters across the horizontal profile of the beaches were noted. In both studied beaches a higher number of bacteria able to decompose macromolecular compounds were recorded in the surface as compared to the subsurface sand layer.

Indian Ocean coral reef environments off Mascarenes (Réunion and Rodrigues Islands), Comores archipelago (Mayotte) and Eparses atolls (Europa, Glorieuses, Juan de Nova and Tromelin), were sampled in 2007 and 2009 for environmental parameters and benthic diatoms studies. This preliminary note documents the nutrient concentrations [NO3−, NO2−, PO4− and Si(OH)4] of coastal waters in diverse sites and examines the possible relationship between nutrient concentration and anthropogenic pressure. The pool of data is restricted, but the marine coastal environments of Réunion, Rodrigues and Mayotte exhibit, on average, higher levels of nutrient concentration, as compared to Eparses atolls, probably in relation to the degree of urbanisation. A project based on the study of benthic diatom assemblages will offer the opportunity to search for possible anthropogenic signatures.

Monitoring data on water pH are presented for the period between 1972 and 2009 from the sampling stations Längden and Storgadden, at the entrance to the Gulf of Finland, Baltic Sea. The overall pH in the area ranged from 9.2 to 7.4, on average 8.1, and showed a significant decreasing trend during the winter period corresponding to a median annual decrease of 0.006. The data corroborate previous findings about a seasonal effect, where pH is higher during summer than winter.