Distribucija različitih polutanata u tkivima pet komercijalnih vrsta riba iz Dunava kod Beograda

Abstract

Akvatični ekosistemi su danas ugroženi na globalnom nivou, stoga je u cilju održivog upravljanja vodenim resursima neophodno uspostaviti kontinuirani monitoring njihovog kvaliteta. Položaj riba na vrhu lanca ishrane i upotreba u ishrani ljudi čini ih važnim za procenu kontaminacije akvatičnih ekosistema toksičnim supstancama. U okviru ove disertacije vršena je procena distribucije različitih polutanata na tri lokacije na Dunavu: Batajnica, Veliko ratno ostrvo i Grocka, u periodu od novembra 2012. godine do marta 2014. godine. Na osnovu analize relativne zastupljenosti (abundancije) i masenog udela prisutnih vrsta riba u ukupnom ulovu, kao i bioloških i ekoloških karakteristika samih vrsta, na ispitivanim lokalitetima najpre jeodređenokoje vrste bi mogle biti optimalne indikatorske vrste, tako da su u daljim istraživanjima korišćeni štuka, deverika, krupatica,somi smuđ. Na uzorcima soma,primenom masene spektrometrije sa induktivno spregnutom plazmom (ICP-MS),ispitana je distribucija 11 elemenata u tkivima, kao i njihove koncentracijeu različitim segmentima mišića, škrga, jetre i crevakako bi se utvrdio potencijal korišćenja ovih tkiva u monitoringu populacija riba. Potencijalna korelacija između koncentracije metala i elemenata u tragovima u mišiću sa koncentracijama u krljuštima i analnom peraju ispitana je na jedinkama štuke, deverike, krupatice, soma i smuđa, u cilju razvoja neinvazivnih metoda monitoringa kvaliteta ribljeg mesa. Takođe, ispitano je i prisustvo akumulacije organohlornih zagađivača (polihlorovanih bifenila i pesticida) kod jedinki deverike i smuđa primenom gasne hromatografije sa detektorom elektronskog zahvata(GC-ECD). Histopatološke promene praćene su na škrgama i jetri deverike i smuđa, kako bi se utvrdio potencijal korišćenja histoloških analiza u razvoju metoda monitoringa populacija riba. Rezultati su ukazali na visok nivo diferencijalne akumulacije elemenata među analiziranim tkivima u somu. Najviši sveukupni nivo akumulacije uočen je u kičmenom pršljenu, bubrezima i jetri, dok su minimalne vrednosti uočene u žučnoj kesi, mišiću, mozgu i ribljem mehuru. Akumulacija elemenata u mišiću i koži,kao i u škržnim filamentima i luku, značajno se razlikovala za većinu elemenata, dok između dva ispitivana dela jetre, proksimalnog i distalnog, nije bilo razlika u koncentracijama analiziranih elemenata. U proksimalnom i medijalnom segmentu creva uočen je isti akumulacioni nivo, dok su u oba segmenta zabeležene značajno više koncentracije Co i Zn i niže koncentracije Mn u odnosu na distalni segment. Nije uočena značajna korelacija koncentracija elemenata između mišića i krljušti kod ispitivanih vrsta, pa se može zaključiti da metoda korišćenja krljušti za procenu kontaminacije mišića datim elementimanije zadovoljavajuća, mada se može koristiti kao metoda ranog upozorenja na kontaminaciju tkiva. Koncentracije organohlornih zagađivača bile su ispod propisanih maksimalno dovozvoljenih vrednosti. Na akumulaciju organohlornih jedinjenja utiču kako položaj ribe u lancu ishrane tako i sadržaj lipida, međutim u ovom istraživanju nisu uočene značajne razlike u koncentracijama PCB i pesticida između deverike i smuđa. Histopatološkom analizom utvrđene su više prosečne vrednosti nivoa histopatoloških promena u škrgama deverike, što je i očekivano imajući u vidu da su škrge riba u stalnom kontaktu sa supstancama koje se nalaze u vodi koja ih okružuje, pa predstavljaju relevantne indikatore izloženosti riba zagađivačima u vodi. Ukupni histopatološki indeks jetre nije se značajno razlikovao među vrstama.

Aquatic ecosystems are today globally endangered;thus, in order to ensure sustainable water resources management, it is necessary to establish continuous monitoring of their quality. Considering that fish are situated at the top of the food chain and used for human nutrition, it makes them important for the assessment of contamination of aquatic ecosystems with toxic substances. In scope of this dissertation,the estimation of the distribution of different pollutants was carried out at three localities on the Danube: Batajnica, Veliko Ratno Ostrvo, and Grocka, in the period from November 2012 to March 2014. Based on the analysis of abundance and mass fraction of individual species in the total catch, as well as their biological and ecological characteristics, the optimal indicator species for this study were determined, and accordingly the following species were used northern pike, freshwater bream, white bream, wels catfish, and pike-perch. The distribution of 11 elements wasassessed in the wels catfish tissue samples by inductively coupled plasma mass spectrometry(ICP-MS), as well as their concentrations in different segments of muscles, gills, liver, and intestine, in order to determine the potential for the use of these tissues in monitoring fish populations. The potential relationship of metal and trace element concentrations in the muscle and their concentrations in scales and anal fins was assessed in northern pike, freshwater bream, white bream, wels catfish and pike-perch in order to develop non-invasive methods for monitoring the quality of fish meat. Using the gas chromatography with electron capture detector(GC-ECD), concentrations of organochlorine pollutants (polychlorinated biphenyls and pesticides) in freshwater bream and pike-perch were determined. Histopathological changes were assessed in gills and liver of freshwater bream and pike-perch in order to determine the potential for using histological analyses in the development of methods for monitoring fish populations. The results indicated a high level of differential accumulation of elements among the analyzed tissues in wels catfish. The highest overall accumulation level was observed in vertebra, kidneys, and liver, while minimal values were observed in gallbladder, muscle, brain, and swim bladder. The accumulation of elements in the muscle and skin, as well as in the gill filaments and gill arch, differed significantly among most elements, while between the two examined parts of the liver, proximal and distal, there were no differences in concentrations of the analyzed elements. The same accumulation level was observed in the proximal and medial segments of the intestine, while both segments had significantly higher concentrations of Co and Zn and lower Mn concentration in comparison with the distal segment. There were no significant correlations between muscle and scales in element concentrations in all investigated species, which indicates that the method of using scales is inadequate for assessing muscle contamination with these elements, but that it can be used as an early warning method for assessing overall tissue contamination. Concentrations of organochlorine contaminants were below the prescribed maximum allowed levels. While the accumulation of organochlorine compounds is affected by both the position of the fish in the food chain and the lipid content, no differences in concentrations of polychlorinated biphenyls and pesticides between the freshwater bream and pike-perch were observed in this study. Histopathological analysis revealed higher average histological scores in the gills of freshwater bream, which was expected, given that the gills are in constant contact with the substances found in the surrounding water, which makes them good indicators of fish exposure to pollutants in water. The total histopathological index of the liver did not differ significantly between species.