Spatial distribution of trace metals in the Krka River, Croatia: an example of the self-purification

The spatial distribution of dissolved and total trace metals (Zn, Cd, Pb and Cu) in the Krka River (partly located in the Krka National Park) has been studied using a "clean" sampling, handling and analysis technique. Differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) has been used for trace metal analysis. The Krka River has been divided into the upper and lower flow region with respect to the metals concentration and main physico-chemical parameters. A significant increase in trace metal concentration as the result of the untreated waste water discharge downstream of Knin Town has been registered in the upper flow region. Due to a specific characteristic of the Krka, the so-called self-purification process, a decrease in the elevated trace metals concentration from the water column takes place at numerous small lakes formed by tufa barriers (at the end of the upper flow region). The clean groundwater input at the beginning of the lower flow region additionally contributes to the observed decrease in trace metals concentration in the Krka, maintaining them at a very low level in the remaining region of fresh-water flow. The determined median total concentrations were zinc 120-7400 ng l(-1), cadmium 3-8 ng l(-1), lead 11-250 ng l(-1) and copper 110-440 ng l(-1). Karst rivers, such as the Krka River, with extremely low natural concentrations of trace metals are highly sensitive to the anthropogenic influence. Therefore, such aquatic systems require implementation of strict protection regimes in the entire catchments area.     

Hemosporidian blood parasites in seabirds—a comparative genetic study of species from Antarctic to tropical habitats

Whereas some bird species are heavily affected by blood parasites in the wild, others reportedly are not. Seabirds, in particular, are often free from blood parasites, even in the presence of potential vectors. By means of polymerase chain reaction, we amplified a DNA fragment from the cytochrome b gene to detect parasites of the genera Plasmodium, Leucocytozoon, and Haemoproteus in 14 seabird species, ranging from Antarctica to the tropical Indian Ocean. We did not detect parasites in 11 of these species, including one Antarctic, four subantarctic, two temperate, and four tropical species. On the other hand, two subantarctic species, thin-billed prions Pachyptila belcheri and dolphin gulls Larus scoresbii, were found infected. One of 28 thin-billed prions had a Plasmodium infection whose DNA sequence was identical to lineage P22 of Plasmodium relictum, and one of 20 dolphin gulls was infected with a Haemoproteus lineage which appears phylogenetically clustered with parasites species isolated from passeriform birds such as Haemoproteus lanii, Haemoproteus magnus, Haemoproteus fringillae, Haemoproteus sylvae, Haemoproteus payevskyi, and Haemoproteus belopolskyi. In addition, we found a high parasite prevalence in a single tropical species, the Christmas Island frigatebird Fregata andrewsi, where 56% of sampled adults were infected with Haemoproteus. The latter formed a monophyletic group that includes a Haemoproteus line from Eastern Asian black-tailed gulls Larus crassirostris. Our results are in agreement with those showing that (a) seabirds are poor in hemosporidians and (b) latitude could be a determining factor to predict the presence of hemosporidians in birds. However, further studies should explore the relative importance of extrinsic and intrinsic factors on parasite prevalence, in particular using phylogenetically controlled comparative analyses, systematic sampling and screening of vectors, and within-species comparisons.     

Climate change impacts on a pine stand in Central Siberia

The objective of this paper is to analyse the impacts of climate change on a pine forest stand in Central Siberia (Zotino) to assess benefits and risks for such forests in the future. We use the regional statistical climate model STARS to develop a set of climate change scenarios assuming a temperature increase by mid-century of 1, 2, 3 and 4 K. The process-based forest growth model 4C is applied to a 200-year-old pine forest to analyse impacts on carbon and water balance as well as the risk of fire under these climate change scenarios. The climate scenarios indicate precipitation increases mainly during winter and decreases during summer with increasing temperature trend. They cause rising forest productivity up to about 20 % in spite of increasing respiration losses. At the same time, the water-use efficiency increases slightly from 2.0 g C l^?1 H₂O under current climate to 2.1 g C l^?1 H₂O under 4 K scenario indicating that higher water losses from increasing evapotranspiration do not appear to lead to water limitations for the productivity at this site. The simulated actual evaporation increases by up to 32 %, but the climatic water balance decreases by up to 20 % with increasing temperature trend. In contrast, the risk of fire indicated by the Nesterov index clearly increases. Our analysis confirms increasing productivity of the boreal pine stand but also highlights increasing drought stress and risks from abiotic disturbances which could cancel out productivity gains.     

Major, minor and trace element content derived from aquacultural activity of marine sediments (Central Adriatic, Croatia)

Introduction and purpose

Studies examining the environmental impact of marine aquaculture have increased significantly in number during the last few decades. The present paper investigates a region of rapid growth in intensive aquaculture and its influence on the local marine ecosystem.

Discussion

This study was undertaken with the specific aim of assessing the effect of fish farming on marine sediment at a farm near the island of Vrgada in the Central Adriatic. Data obtained regarding major (Si, Al, K, Na, Fe, Ca, Mg), minor (Mn, P, Ti) and trace (As, Au, Ba, Cd, Co, Cr, Cs, Cu, Ga, Hf, Hg, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Se, Sr, Ta, Th, Tl, U, V, Y, Zn, Zr) elements were used to estimate the spatial and temporal distribution of metals in the sediment and their possible relationship with local aquacultural activity.

Results

Although the measured concentrations of heavy metals in sediment below fish cages were notably different and potentially a result of farming activity, the values were generally lower than background concentrations observed in the Central Adriatic. In contrast, concentrations of heavy metals at a reference site unaffected by aquaculture varied from lower levels to values even higher than those observed below the high-production cages. Furthermore, calculated environmental index values indicate that the sediment below the farm is either uncontaminated or suffers from only low levels of contamination.

Conclusion

Such results suggest that the effect of observed fish farm activity on the local marine ecosystem is practically negligible.     

A solid-phase microextraction method for the in vivo sampling of MTBE in common reed (Phragmites australis)

Phytoscreening of phytoremediation-based plantings is discussed as a promising monitoring tool in literature. We developed and applied an analytical procedure for the in vivo sampling of methyl tert-butyl ether (MTBE) in the common reed (Phragmites australis) from a phytoremediation site highly polluted with MTBE. The approach uses solid-phase microextraction (SPME) with the SPME fibre directly introduced into the aerenchyma of the plant stem. For optimising the analytical procedure and estimating the capability of the proposed method, laboratory tests on the microcosm scale and field studies over one vegetation period were carried out. Furthermore, the results of in vivo SPME sampling were compared with those obtained with the traditional approach for analysing plants using dynamic headspace analysis. The MTBE signals detected within the plants were also correlated with the concentration in the water phase. The discussion of results showed the feasibility of the proposed method for a qualitative phytoscreening of volatile organic compounds present in wetland plants.     

Live fast, die young: flexibility of life history traits in the fat-tailed dwarf lemur (Cheirogaleus medius)

The fat-tailed dwarf lemur, Cheirogaleus medius, occurs in ecologically very different habitat types (rainforest and dry forest) across Madagascar. Its extraordinary biological characteristics, such as monogamy and long-term hibernation, allow us to investigate behavioral, ecological, and physiological flexibility of this species in populations across different ecological environments. This study aims to determine whether different life history and physiological traits show variation in adaptation to the differing ambient conditions or are conservative and influenced more by the organism's evolutionary history. We compared body masses, life history traits, social organization, and hibernation duration of two populations of C. medius, one from a littoral rainforest and one from the dry deciduous forest. We revealed clear geographical differences in the length of hibernation duration as well as, more surprisingly, in life history traits. We found that this species' reproductive strategies seem to be highly flexible. Animals in the rainforest can spend more time in the active state due to a shorter hibernation period, but have, in general, a shorter life expectancy due to higher mortality rates. Hence, they seem to maximize their total reproductive output with higher reproductive rates (larger litter sizes, greater number of litters). Home ranges and social organization, on the other hand, did not vary between habitats, suggesting that the general requirements of this species are independent of environmental conditions. In conclusion, some life history traits, formerly assumed to be genetically fixed parameters of primate species, prove in fact to be highly flexible. Different populations of the same species show distinct adaptations according to the prevailing conditions in order to maximize individual reproductive output.     

Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles

The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing β-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein.