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Dragun Z.,Ruder Boskovic Institute | Tepic N.,National Center for External Evaluation of Education | Krasnici N.,Ruder Boskovic Institute | Teskeredzic E.,Ruder Boskovic Institute
Environmental Science and Pollution Research

The study of metal bioaccumulation in the gills of European chub (Squalius cephalus) was conducted in September 2009 at the medium-sized rural river Sutla, characterized by agricultural and municipal type of water contamination. The concentration ranges were established for the first time in the soluble, metabolically available fractions of chub gills for 12 metals, which are environmentally extremely relevant and yet only seldom studied, as follows in a decreasing order: K, 225–895 mg L−1; Na, 78–366 mg L−1; Ca, 19–62 mg L−1; Mg, 13–47 mg L−1; Rb, 164–1762 μg L−1; Sr, 24–81 μg L−1; Ba, 13–67 μg L−1; Mo, 1.3–16 μg L−1; Co, 0.7–2.7 μg L−1; Li, 0.4–2.2 μg L−1; Cs, 0.2–1.9 μg L−1; and V, 0.1–1.8 μg L−1. The concentrations of Fe (1.6–6.4 mg L−1) and Mn (16–69 μg L−1) were also determined and were in agreement with previous reports. By application of general linear modelling, the influence of different abiotic (metal exposure level) and biotic parameters (fish sex, age, size and condition) on metal bioaccumulation was tested. It was established that bioaccumulation of many metals in fish depended on various physiological conditions, wherein Ba could be singled out as metal exhibiting the strongest association with one of biotic parameters, being significantly higher in smaller fish. However, it was also undoubtedly demonstrated that the concentrations of three metals can be applied as reliable indicators of metal exposure even in the conditions of low or moderate water contamination, such as observed in the Sutla River, and those were nonessential elements Li and Cs and essential element Fe. The results of our study present an important contribution to maintenance of high ecological status of European freshwaters, through enrichment of knowledge on the bioaccumulation of various metals in gills of European chub as frequently applied bioindicator species in monitoring of water pollution. © 2016 Springer-Verlag Berlin Heidelberg Source

Radovic A.,University of Zagreb | Bukovec D.,Croatian Natural History Museum | Tvrtkovic N.,Croatian Natural History Museum | Tepic N.,National Center for External Evaluation of Education
International Journal of Sustainable Development and World Ecology

The authors researched changes in specific habitat types in areas considered to be the most important in Croatia for protection of endangered bird fauna during the period 1990-2000. The analysis focused on four areas in the continental part of Croatia (Danube and Drava River alluvium, Pokupsko depression, Sava River basin, Upper Drava River basin) and four areas in the Mediterranean part (Neretva River estuary, NW part of North Dalmatia, Pasko field, Lake Vrana). For the classified habitat types, changes in Corine land cover databases in 1990 and 2000 were analysed. The greatest changes in habitat were detected along the Danube and Drava River alluvium, where more than 8% of the total area changed habitat type, as well along the Sava River basin, where approximately 5% of the total area and the greatest absolute area changed habitat type. The most pronounced changes were detected in forest habitats, where forest degradation prevents the maturation of forest stands. The authors discuss which bird species listed in the Red Data Book of Birds of Croatia may be most impacted by the detected changes in habitat. Special attention was given to a comparison of habitat changes in the Nature Park Lonjsko polje between two raptor species, Aquila pomarina and Haliaeetus albicilla, according to the suitability of habitats where changes occurred. © 2011 Taylor & Francis. Source

Gasparovic B.,Ruder Boskovic Institute | Djakovac T.,Ruder Boskovic Institute | Tepic N.,National Center for External Evaluation of Education | Degobbis D.,Ruder Boskovic Institute
Continental Shelf Research

Surface-active organic substances (SAS), nutrients, chlorophyll a (Chl a), dissolved oxygen (O2), salinity (S) and temperature (T) were measured approximately monthly in the northern Adriatic Sea (NA) during two years. Results were elaborated for two stations of different trophic status. Exhaustive statistical examinations of measured variables were performed to contribute to better understanding of the processes and interdependence of the measured parameters. The results of those analyses allowed the region to be described based on several groups of data relevant for particular processes. Chl a appear to be independent parameter; orthosilicate, nitrite and ammonium represent the parameter group most relevant for regeneration processes; the second group includes nutrients dominant in freshwater inputs (orthophosphate and nitrate), while in the third group are parameters related to primary production processes (T, O2, organic phosphorus and SAS). Probably due to time lags between nutrient uptake and phytoplankton growth as well as between cells growth/division and SAS release, both, the correlation between nutrients and Chl a and the correlation between Chl a and SAS were not statistically significant. Although significantly higher nutrient and Chl a concentrations were found in the mesotrophic western part of the region in comparison to the oligotrophic eastern part, the SAS concentration differences were less marked. It is assumed that more OM is produced, but also at the same time remineralized, at the mesotrophic western part, leading to higher concentrations of regenerated nutrients there. Presence of different phytoplankton taxa and/or fractions (micro and nano) at the two stations may have also contributed to minimize the difference in SAS contents. Higher SAS acidities were noticed in the mesotrophic than in the oligotrophic part. © 2011 Elsevier Ltd. Source

Cukrov N.,Ruder Boskovic Institute | Tepic N.,National Center for External Evaluation of Education | Omanovic D.,Ruder Boskovic Institute | Lojen S.,Jozef Stefan Institute | And 3 more authors.
International Journal of Environmental Analytical Chemistry

Multivariate statistical analyses were applied on the measured physico-chemical (Cd, Pb, Cu, Zn, Mg, Ca, O2, alkalinity, temperature, pH, SAS, DOC and DIC) and isotopic parameters (δ13C and δ18O) to estimate and distinguish anthropogenic from natural influences to the water system of the Krka River. Analyses were conducted on the data collected during six years from twelve sampling sites. On the basis of orientation, positioning and grouping of parameters arranged by biplots, four main hypotheses were defined and finally statistically confirmed. Thereof, two main and distinct processes occurring in the Krka River could be highlighted: (i) upstream pollution, caused by the inflow of untreated waste-waters of city of Knin and (ii) downstream self-purification, caused by the sedimentation and/or co-precipitation of pollutants coupled by the inflow of clean subterranean water (groundwater recharge). Grouping of (i) hydrological and carbon cycle connected parameters, and (ii) anthropogenically influenced correlated parameters were proposed as a result of statistical analysis. Regarding the pH, it is shown that a stream section influenced by the subterranean inflow of Zrmanja River is statistically significantly different for all sampling campaigns during six years, being lower for about 0.5 pH unit. © 2012 Copyright Taylor and Francis Group, LLC. Source

Gasparovic B.,Ruder Boskovic Institute | Godrijan J.,Ruder Boskovic Institute | Frka S.,Ruder Boskovic Institute | Tomazic I.,Ruder Boskovic Institute | And 8 more authors.
Marine Environmental Research

A systematic investigation of non-phosphorus containing glycolipids (GL) was conducted in the northern Adriatic Sea during two years at two stations with different nutrient loads. GL concentration varied both spatially and temporally, with values of 1.1-21.5μg/L and 0.4-44.7μg/L in the particulate and the dissolved fraction, respectively. The highest concentrations were measured during summer in surface waters and at the more oligotrophic station, where GL yields (% of total lipids) were often higher than 20% and 50% in the particulate and dissolved fractions, respectively. To obtain more insight into factors governing GL accumulation autotrophic plankton community structure (pico-, nano- and microplankton fractions), chlorophyll a, heterotrophic bacteria and nutrient concentrations were measured together with hydrographic parameters and sunlight intensity. During the investigated period smaller autotrophic plankton cells (pico- and followed by nanoplankton) prevailed in abundance over larger cells (microplankton), which were found in large numbers in freshened surface samples. Several major findings resulted from the study. Firstly, during PO4 limitation, particularly at the oligotrophic station, enhanced glycolipid instead of phospholipid accumulation takes place, representing an effective phosphate-conserving mechanism. Secondly, results suggest that at seawater temperatures 19°C autotrophic plankton considerably accumulate GL, probably to achieve thermal stability. Thirdly, high sunlight intensities seem to influence increased GL accumulation; GL possibly plays a role in cell mechanisms that prevent/mitigate photooxidation. And finally, substantial accumulation of GL detected in the dissolved fraction could be related to the fact that GL do not contain biologically relevant elements, like phosphorus, which makes them an unattractive substrate for enzyme activity. Therefore, substantial portion of CO2 could be removed from the atmosphere in P-limited regions during summer via its capture by plankton and conversion to GL. © 2013 Elsevier Ltd. Source

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