The first record of the Chinese pond mussel Sinanodonta woodiana (Lea, 1834) in Montenegro

Sinanodonta woodiana (Lea, 1834), Chinese pond mussel (Bivalvia: Unionoida: Unionidae) is one of the most invasive aquatic macroinvertebrate species found in Europe. We report the Chinese pond mussel for the first time in Montenegro, in August 2012, in Lake Šasko (Adriatic part of the Central Mediterranean subarea). One specimen of the Chinese pond mussel was observed in a habitat with a predominantly silt-clay substrate. The main pathway of species introduction was evaluated to be via fish stocking. [Projekat Ministarstva nauke Republike Srbije, br. III 43002 i br. ON 173025

STRUKTURA ZOOPLANKTONA U MEĐUSOBNO POVEZANIM PLITKIM JEZERIMA

The research of zooplankton diversity, abundance and trophic structure was conducted during the summer period in pelagial zone on the longitudinal profile of the Sutla River Backwater. Investigated site consists of two interconnected basins: transparent Upper Basin with submerged macrophytes and turbid Lower Basin without macrophytes in the littoral zone. In the Upper Basin, abundance and diversity of zooplankton in the pelagial was higher in comparison to the Lower Basin, with prevailing species of genus Keratella as microfilter-feeder, and genera of Polyartha and Trihocerca as macrofilterfeeder rotifers. On the contrary, in the Lower Basin, crustaceans dominated in abundance. Microfilter-feeder cladoceran (Bosmina longirostris) and larval and adult stages of macrofilter-feeder copepod (Macrocyclops albidus) prevailed in the Lower Basin. Fish predation pressure was more pronounced in the pelagial of the Upper Basin, indicated by low cladoceran abundance in the surface layer. Although the studied basins were interconnected, results indicate significant (Mann-Whitney U test, p < 0.05) differences in the zooplankton structure as a potential result of the macrophyte impact on environmental conditions and fish predation pressure.Istraživanje raznolikosti, abundancije i trofičke strukture zooplanktona provedeno je tijekom vegetacijskog razdoblja na pelagičkim postajama longitudinalnog profila rukavca rijeke Sutle koji se sastoji od dva međusobno povezana bazena. Gornji bazen veće je prozirnosti i sa submerznim sastojinama makrofita, Donji bazen veće je mutnoće i bez makrofita. U Gornjem bazenu, brojnost i raznolikost zooplanktona u pelagijalu je bila veća u odnosu na Donji bazen, a prevladavali su kolnjaci, detritivorni-mikrofiltratori roda Keratella i algivorni-makrofiltratori rodova Polyartha i Trihocerca. U Donjem bazenu brojnost planktonskih rakova bila je veća u odnosu na Gornji bazen, a prevladavali su mikrofiltratorski rašljoticalci (Bosmina longirostris) te makrofiltratorski ličinački i adultni stadiji veslonožaca (Macrocyclops albidus). Predacijski pritisak riba bio je izraženiji u pelagijalu Gornjeg bazena, na što ukazuje manja brojnost Cladocera u površinskom sloju. Iako su istraživani bazeni međusobno povezani, rezultati rada ukazuju na značajne razlike (Mann-Whitney U test, p < 0.05) u strukturi zooplanktona kao rezultat utjecaja makrofita i predacije riba na promjenu uvjeta okoliša

The first record of the Chinese pond mussel Sinanodonta woodiana (Lea, 1834) in Montenegro

Sinanodonta woodiana (Lea, 1834), Chinese pond mussel (Bivalvia: Unionoida: Unionidae) is one of the most invasive aquatic macroinvertebrate species found in Europe. We report the Chinese pond mussel for the first time in Montenegro, in August 2012, in Lake Šasko (Adriatic part of the Central Mediterranean subarea). One specimen of the Chinese pond mussel was observed in a habitat with a predominantly silt-clay substrate. The main pathway of species introduction was evaluated to be via fish stocking.Projekat ministarstva br. III 43002 i br. ON 17302

Entomofauna sastojina submerznih makrofita u umjetnim ujezerenjima (Park prirode Papuk)

In this study diversity, abundance and functional feeding guild of aquatic entomofauna were assigned within submerged macrophyte stands in Jankovac Stream reservoirs (Papuk Nature Park). The main aims of this study were to analyse: (i) physico-chemical parameters and food resources; (ii) abundance and diversity and (iii) functional feeding guilds of entomofauna. Between reservoirs non significant differences were observed in regard to abiotic or biotic parameters, except higher abundance of active fi lterers in vegetated littoral zone of Reservoir 1 (R1M) than in Reservoir 2 (R2M). Other parameters mostly showed significant seasonal oscillations. In total 19 taxa were identified, among them 14 in R1M, and half less in R2M. Highest abundance was reached in R1M in winter (544 ind m-2), and in R2M in spring (472 ind m-2). Ephemeroptera (R1M 66 %, R2M 76 %) with domination of Cloeon sp., and Diptera (23 % in R1M and R2M) with dominated Tanitarsini specimens contributed at most in total abundance. Among feeding guilds the greatest contribution in abundance achieved detritivores (81 %). Results of this study suggested that food resources and biotic interactions are main drivers in structuring entomofauna, i.e., macroinvertebrate community in submerged macrophyte stands.U provedenom istraživanju razmatrana je raznolikost, abundancija i funkcionalne hranidbene skupine akvatičke entomofaune u submerznim sastojinama umjetnih ujezerenja potoka Jankovac (Park prirode Papuk). Glavni ciljevi ovog istraživanja bili su analizirati: (i)fizičko-kemijske čimbenike i izvore hrane; (ii) abundanciju i raznolikost te (iii) funkcionalne hranidbene skupine entomofaune. Između ujezerenja nisu utvrđene značajne razlike abiotičkih niti biotičkih čimbenika, izuzev veće abundancije aktivnih filtratora u litoralnoj zoni s makrofitima u ujezerenju 1 (R1M) u odnosu na ujezerenje 2 (R2M). Ostali istraživani čimbenici uglavnom su ukazivali na značajne sezonske razlike. Ukupno je utvrđeno 19 svojti, od kojih je 14 svojti bilo prisutno na postaji R1M, a upola manje na postaji R2M. Najveća abundancija postignuta je zimi na postaji R1M (544 jed. m-2) dok je na postaji R2M maksimum abundancije postignut u proljeće (472 jed. m-2). Ephemeroptera (R1M 66 %, R2M 76 %) s dominantnom svojtom Cloeon sp. i Diptera (23 % u R1M i R2M) s dominacijom jedinki iz skupine Tanitarsini najviše su pridonijeli ukupnoj abundanciji. Između funkcionalnih hranidbenih skupina detritovori su postigli najveći udio (81 %) u ukupnoj abundanciji. Rezultati ovog istraživanja ukazuju da su izvori hrane i interakcije unutar vodenih biocenoza bile glavne odrednice u strukturiranju entomofaune odnosno makrozoobentosa u sastojinama submerznih makrofita

IMPACT OF WATER LEVEL FLUCTUATION IN THE SHAPING OF ZOOPLANKTON ASSEMBLAGE IN A SHALLOW LAKE

Promjene u okolišu pod utjecajem su globalnih klimatskih promjena i snažno utječu na ekosustav plitkih jezera te narušavaju relevantne parametre, na primjer biološku raznolikost i prozirnost vode. Tijekom ljeta 2012. i 2013. provedeno je istraživanje zooplanktona u mrtvaji Škrčev put, u porječju rijeke Krapine (SZ Hrvatska, Europa). Cilj istraživanja bio je utvrditi utjecaj promjena hidrološkog režima u kratkom vremenskom razdoblju na uvjete okoliša, pokrovnost makrofitima, strukturu zooplanktona i riba u plitkom jezeru umjerenog područja. U razdoblju od godinu dana razina vode se podigla za 2 metra, što je uzrokovalo značajno smanjenje prisutnosti plutajućih makrofita (npr. Nuphar lutea), dok su vrijednosti prozirnosti, ortofosfata iklorofila a porasle. Ovi izmijenjeni ekološki uvjeti odrazili su se na promjenu, od jezera pokrivenog plutajućim makrofitima tijekom niske razine vode u jezero s dominacijom fitoplanktona tijekom visoke razine vode. Ova promjena značajno se odrazila na promjene u sastavu zooplanktona. Rezultati ukazuju da su ribe utjecale na smanjenje populacije rašljoticalaca, dok su populacije kolnjaka i veslonožaca zadržale visoku brojnost, odnosno nisu direktno izložene predaciji riba. Zaključno, planktonska zajednica je, čak i kratkoročno, podložna promjenama uslijed izmijenjenih okolišnih uvjeta.Shallow lakes are strongly affected by global climate changes reflected in significant parameters of ecosystem deterioration, i.e. biodiversity decrease, and water turbidity. Zooplankton research in Škrčev kut oxbow lake (Krapina River watershed, NW Croatia, Europe) was conducted during the summer of 2012 and 2013 with the aim to determine the effect of inter-annual, short-timescale changes of hydrological regime on environmental conditions, macrophytes, zooplankton and fish assemblage within an oxbow lake in the temperate region. Within one-year period the water level increased by 2 meters. This caused a significant reduction of floating-leaved macrophytes (i.e. Nuphar lutea), while turbidity, ortho-phosphate and chlorophyll a concentrations increased. These altered ecological conditions were reflected in the shift from floating-leaved macrophytes at the lower water level to phytoplankton-dominated lake at the higher water level. Zooplankton underwent significant alteration in assemblage. The results suggest that fish preference suppressed cladocerans and enhanced the rotifer and copepod abundance. Our results indicate that even in a short-timescale zooplankton assemblage mediates in the modification of ecosystem functioning

The first record of the Chinese pond mussel Sinanodonta woodiana (Lea, 1834) in Montenegro

Sinanodonta woodiana (Lea, 1834), Chinese pond mussel (Bivalvia: Unionoida: Unionidae) is one of the most invasive aquatic macroinvertebrate species found in Europe. We report the Chinese pond mussel for the first time in Montenegro, in August 2012, in Lake Šasko (Adriatic part of the Central Mediterranean subarea). One specimen of the Chinese pond mussel was observed in a habitat with a predominantly silt-clay substrate. The main pathway of species introduction was evaluated to be via fish stocking.Projekat ministarstva br. III 43002 i br. ON 17302

“Raspetljavanje” hranidbenih mreža u litoralu plitkih jezera umjerene zone

Elucidation of food web interactions provides a better understanding of ecosystem functioning, indicates anthropogenic impacts which often cause alterations in environmental conditions and deterioration in feeding networks in terrestrial and aquatic ecosystems. The importance of microfauna and macroinvertebrates in the littoral zones of shallow waters has been poorly studied regarding their trophic interactions. This study compares invertebrate assemblage and food web interactions among epiphyton, zooplankton and benthic macroinvertebrates across structural heterogeneity in the littoral zone of three temperate shallow water bodies. Submerged and structurally-complex stands of Ceratophyllum demersum inhabited a higher abundance of cladocerans and supported a higher diversity and biomass of epiphytic protozoans and invertebrates than floating-leaved Nuphar lutea stands. Analysis of the ecosystem functioning illustrated the increased biomass of macroinvertebrate predators and a preference of predation over planktonic crustaceans in more complex macrophyte stands. Food webs displayed higher complexity and size with habitat heterogeneity, while epiphyton and zooplankton shared an important fraction in food resources among the invertebrate trophic network. Results of food web modelling indicated zooplankton and epiphyton as more vulnerable to invertebrate predation in the complex submerged macrophytes than in the floating-leaved macrophyte stands. Integrated approaches to community, ecosystem and food webs in explanation of complex trophic interactions in the littoral zones confirmed an increase in diversity and food-web functional complexity with structural heterogeneity of microhabitats.Razjašnjenje interakcija u hranidbenoj mreži omogućuje bolje razumijevanje funkcioniranja ekosustava te indikaciju antropogenih učinaka koji često uzrokuju promjene uvjeta okoliša i narušavanje hranidbene mreže kopnenih i vodenih ekosustava. Trofičke interakcije mikrofaune i makrozoobentosa slabo su proučavane u priobalnim (litoralnim) zonama plitkih vodenih tijela. Cilj ovog rada je usporediti interakcije beskralježnjaka i izvora hrane, uključujući epifiton, zooplankton i makrozoobentos u strukturno heterogenim litoralnim zonama triju plikih jezera umjerenog pojasa. U submerznim i strukturno složenim makrofitskim sastojinama vrste Ceratophyllum demersum rašljoticalci su razvili populacije velike brojnosti, a također je u njima zbilježena veća raznolikost i biomasa epifitskih protozoa i beskralježnjaka u usporedbi sa sastojinama plutajuće vrste Nuphar lutea. Analiza funkcioniranja ekosustava ukazivala je na to da je u heterogenim makrofitskim sastojinama povećana biomasa makrozoobentoskih predatora i izraženija je njihova predacija nad planktonskim rakovima. Hranidbene mreže bile su složenije u heterogenima staništima, a epifiton i zooplankton imali su važan udio u hranidbenim resursima unutar hranidbene mreže beskralježnjaka. Modeliranje hranidbenih mreža inidicira veću ranjivost zooplanktona i epifitona na predaciju beskralježnjaka u kompleksnijim, submerznim, makrofitskim sastojinama u odnosu na sastojine plutajućih makrofita. Integrirani pristup s aspekta ekologije biocenoza, ekosustava i hranidbenih mreža u objašnjenju složenih trofičkih interakcija u litoralnoj zoni potvrđuje povećanje raznolikosti i kompleksnosti hranidbenih mreža sa strukturalnom heterogenošću mikrostaništa

Comparison of electrochemically determined metallothionein concentrations in wild freshwater salmon fish and gammarids and their relation to total and cytosolic metal levels

Application of metallothionein (MT) as an early warning sign of metal exposure in aquatic organisms is common in biomonitoring, but there is a huge variability in MT concentrations among different studies. Present research aims to assess MT responses in freshwater fish brown trout (Salmo trutta Linnaeus, 1758) and gammarids(Gammarus balcanicus Schäferna, 1922 and Echinogammarus acarinatus Karaman, 1931) as indicators of metal exposure within the freshwater karst environment (Krka River, Croatia). Sampling was performed upstream (reference site) and downstream (anthropogenically impacted site) of the wastewater discharges in autumn and spring seasons. Brown trout intestine was applied as a bioindicator tissue due to its role in dietborne metal uptake while gammarids were chosen as fish food and potential metal uptake source. Moreover, there is a lack of data on intestinal MT levels, so our results on MT and metal/metalloid concentrations, measured as total and metabolically available cytosolic levels, represent the first data of this kind for the selected indicator species. The results indicated that the ecotoxicological impact of technological and municipal wastewaters on the biota of the karst Krka River was moderate, although higher metal levels at the affected site were evident in both, fish and gammarids. The modified Brdička reaction applied in this study was confirmed as reliable electrochemical technique for MT quantification in both vertebrates and invertebrates, and it indicated higher MT levels in gammarids (1.9–4.1 mg g−1 w.w) than in fish intestine (0.5–2.8 mg g−1 w.w). Due to the lack of the data on MT concentrations in S. trutta and gammarid species G. balcanicus and E. acarinatus, presented results can serve as a preliminary data to establish MT background levels in intestine of wild freshwater fish and gammarids. Obtained MT levels showed species-, tissue- and method- specific differences, so comparison between MT levels should always involve the same species, tissue and measurement method