Еcology, biodiversity and conservation of freshwater mussels family

Slatkovodne školjke iz familije Unionidae, predstavljaju jednu od najznačajnijih i široko rasprostranjenih komponenata vodenih ekosistema kopnenih voda. Ekološka uloga ove taksonomske grupe u vodenim ekosistemima je od velikog značaja, s obzirom da predstavlja bitan element strukture i funkcije bentosnih zajednica. Raznovrsnost i rasprostranjenje unionida, do sada, nije adekvatno proučeno u Srbiji, kako u pogledu broja vrsta, tako i u odnosu na opšte poznavanje rasprostranjenja pojedinih vrsta i faktora koji utiču na pojavu taksona i gustinu populacija. Ciljevi ovog istraživanja bili su: pregled ukupnog broja vrsta u Srbiji; analiza strukture i dinamike populacija unionida; definisanje odnosa vrsta i najznačajnijih parametara okruženja; analiza morfološke varijabilnosti različitih populacija, primenom metoda geometrijske i tradicionalne morfometrije i kao krajnji cilj, procena rizika od izumiranja akvatičnih vrsta na nacionalnom nivou i predlog strategije konzervacije. Materijal korišćen za analizu prikupljen je pri realizacije više nacionalnih i međunarodnih projekata u periodu 2001.-2013. godina. Osim savremenih istraživanja, analizom su obuhvaćeni i istorijski podaci, dobijene na osnovu pregleda dostupne zbirke Ante Tadića, Prirodnjačkog muzeja u Beogradu, iz perioda 1953.-1972. Sveobuhvatnom analizom materijala, na prostoru Srbije je utvrđeno prisustvo 7 vrsta slatkovodnih školjki iz familije Unionidae, svrstanih u četiri roda. Najveći diverzitet i brojnost populacije zabeleženi su u donjim tokovima velikih ravničarskih reka (zoni potamona). U radu je dat detaljan pregled sastava zajednica istraživanih slivova, sa prikazom taksonomskih i ekoloških karakteristika pojedinačnih vrsta. Poredeći istorijske podatke o nalazima vrsta i savremena istraživanja, uočene su promene u veličini areala i populacionoj dinamici pojedinih taksona. Značajno smanjenje areala, odnosno potpuno povlačenje sa prostora gde je nekada nalažena, utvrđeno je za vrstu A. cygnea, a kao njeni refugijumi mogu se označiti lentički ekosistemi kakve su akumulacije, jezera i barsko močvarna područja u Srbiji. Na osnovu istorijskih podataka utvrđeno je da je vrsta U. crassus nekada bila široko rasprostranjena i jedna od najprisutnijih vrsta na celom području Srbije do sredine 70-ih godina prošlog veka. Nakon tog perioda, istraživanjima izvršenim u poslednjih nekoliko dekada, uočen je pad brojnosti populacije ove vrste i samo sporadični nalazi na ograničenom prostoru. Najnovija istraživanja ukazuju na pozitivan populacioni trend ove vrste, pri čemu se naročito izdvaja sliv Save. Ispitivanje odnosa prisutnih vrsta prema fizičko-hemijskim karakteristikama vode na analiziranim lokalitetima, pokazalo je da su najvažniji fizičko-hemijski parametri: koncentracija kalcijuma, ukupna tvrdoća vode, BPK, HPK, koncentracija nitrata i amonijum jona. Rezultati kanonijske korespondentne analize ukazuju na očekivano veću osetljivost vrste U. crassus na BPK5, HPK, koncentraciju nitrata i amonijum jona, odnosno veću toleranciju vrste A. anatina na pomenute faktore. Kao najznačajniji parametri uticaja na zajednicu slatkovodnih školjki, iz grupe teških metala, izdvajaju se koncentracije bakra, olova i kadmijuma u vodi. Rezultati kanonijske korespondentne analize ukazuju na povećanu osetljivost vrste U. crassus na ove faktore, dok je veća tolerancija utvrđena za A. anatina. Primenom metoda geometrijske morfometrije, analizirana je varijabilnost veličine i oblika levog kapka ljušture različitih populacija savremenih uzoraka školjki i analiza jedinki koje su pripadale muzejskim uzorcima. Geometrijsko morfometrijskom analizom recentnih uzoraka potvrđeno je postojanje statistički značajnih međupopulacionih razlika u varijabilnosti veličine i oblika morfoloških struktura. Analizom varijavilnosti morfoloških struktura uzoraka iz muzejske zbirke, primenom metoda geometrijske morfometrije, nije potvrđeno postojanje značajnih razlika u varijabilnosti veličine i oblika različitih podvrsta, izuzev u slučaju U. tumidus. Analizom varijabilnosti ljuštura na osnovu devet dužinskih karaktera, primenom tradicionalnog morfometrijskog pristupa, utvrđeno je postojanje međupopulacionih razlika i sličan trend odstupanja kao i pri geometrijsko morfometrijskoj analizi. Primenom modifikovanog modela ESHIPPO-PD, utvrđen je rizik od izumiranja i prioritet konzervacije na lokalnom nivou za analizirane vrste. Za U. crassus, P. complanata i A. cygnea određen je prvi stepen prioriteta zaštite, odnosno visok nivo rizika od izumiranja na nacionalnom nivou. Umereni rizika od izumiranja (II stepen prioriteta konzervacije) ocenjen je za vrste U. pictorum i A. anatina, dok se za U. tumidus uočava da je rizik od izumiranja manji (III stepen prioriteta zaštite). Analizom elemenata modela (ES+HIPPO+PD), izdvajaju se faktori koji najviše utiču na ugroženost datih vrsta i na taj način omogućavaju definisanje adekvatnih mere konzervacije na nacionalnom nivou.Freshwater mussels from the family Unionidae, represent one of the most significant and widespread components of inland water ecosystems. Ecological role of this taxonomic group within water ecosystems is of great significance being an important structural and functional element of benthic communities. The diversity and distribution of Unionidae have not been researched adequately so far in Serbia, neither the species richness, nor general distribution of individual species and factors affecting the emergence of the taxon and populations density. The aims of this research were: review of total number of species in Serbia; analysis of structure and dynamics of Unionidae populations; definition of relations between species and most significant environment parameters; morphological variability analysis of different populations applying the method of geometric and traditional morphometrics and, as the final aim, risk evalulation regarding aquatic species extinction on national level and a conservation strategy recommendation. Material used for analysis was collected during the realization of several national and international projects during the period 2001-2013. Besides contemporary researches, the analysis also includes historical data obtained from available collection of Ante Tadić from the Natural History Museum in Belgrade, period 1953-1972. A thorough material analysis in the region of Serbia led to the determination of presence of 7 fresh water mussels species from family Unionidae, classified into 3 genera. The highest diversity and population abundance were recorded in lower parts large lowland rivers (potamon zone). The detailed overview of communities composition found in the investigated river basins with a review of taxonomic and ecological traits of individual species was presented. The comparison of historical data and contemporary investigations shows there are changes in habitat size and population dynamics of individual taxons. Significant reduction in the habitat size, i.e. complete retreat from the area where it used to be found earlier was determined for the species A. cygnea and lentic ecosystems can be marked as their refugium, such as accumulations, lakes, marsh and swamp regions in Serbia. Based on historical data, it was determined that U. crassus species used to be widespread and one of the most represented species in whole region of Serbia until mid-1970's. After that period, in the investigations carried out during last several decades, the decrease in the number of this population was observed, as well as only sporadic findings in a limited area. The latest investigations indicate to a positive population trend of this species, especially in the Sava river basin. The invastigation of relations among present species based on physical and chemical characteristics of water in analyzed localities has shown that the most important physical and chemical parameters are as follows: Calcium concentration, total water hardness, BPK5, HPK, nitrate concentration and ammonium ion concentration. The results of canonical correspondence analysis indicate to an expectedly higher sensitivity of species U. crassus to BPK, HPK, nitrates and ammonium ion concentration, i.e. greater tolerance of species A. anatina to the above listed factors. The parameters with the most significant influence on freshwater mussels community among the group of heavy metals are the concentrations of copper, lead and cadmium in water. The results of canonical correspondence analysis indicate to an increased sensitivity of species U. crassus to these factors, while a greater tolerance of species A. anatina to these factors was recorded. Using geometric morphometrics method, the size and shape variability of shell left valva of different contemporary shell populations samples were analized, as well as the specimens belonging to museum samples. Geometric morphometrics analysis of recent samples confirms the existence of statistically significant ntrapopulation differences in size and shape variability of morphological structures. Morphological structures variability analysis of museum samples, applying the geometric morphometrics method, does not confirm the existence of significant differences within variability of size and shape of various varieties, except in the case of U. tumidus. Using shell variability analysis based on nine linear characters, applying the traditional morphometric approach, the existence of intrapopulation differences was determined, as well as a similar trend of deviations like in geometric morphometrics analysis. Applying the modified model ESHIPPO-PD, the risk of extinction and the priority of conservation on a local level were determined for the analized species. The first level of protection priority was determined for U. crassus, P. comlanata and A. cygnea, i.e. high extinction risk at local level. A moderate risk (the second level of conservation priority) was estimated for species U. pictorum and A. anatina, while the extiction risk is lower for U. tumidus (the third level of protection priority). The analysis of element included in model ES+HIPPO+PD, singles out the factor of greatest influence on endangeredness of given species

ISOLATION OF MICROPLASTICS FROM FRESHWATER MACROINVERTEBRATES IN THE DANUBE RIVER

The study was conducted on the Danube River, within the project Joint Danube Survey 3 (JDS3). The main aim was to estimate the quantity of microplastics in aquatic ecosystems through passive biological monitoring. Three freshwater species were used for microplastic (MP) isolation from different taxonomic groups of organisms: Mollusca, Oligochaeta, and Chironomidae (Diptera), with the following species: Lithoglyphus naticoides (C. Pfeiffer, 1828), Limnodrilus hoffmeisteri (Claparede, 1862), and Chironomus acutiventris (Wülker, Ryser & Scholl, 1983), respectively. The samples were collected from 6 sites along the Danube River where 540 specimens were examined. The samples were digested by alkaline method (incubation in 10% KOH solution at 60 ⁰C for 24 h) and filtered through a mill silk, 10 µm mesh size. Collected particles were categorized as: fibre, hard plastic, nylon, rubber, or miscellaneous. Categories were divided into subcategories based on the coloration of the particles. Particles ingested by organisms were represented mostly by fibres and fragmented hard plastics, within the size range were from 0.03 to 4.87 mm. A total of 678 MP particles were collected with an average of 4.64 ± 1.59; 1.64 ± 0.46 and 1.24 ± 0.34 items/organism isolated from L. hoffmeisteri, L. naticoides and C. acutiventris, respectively. According to results, L. hoffmeisteri, L. naticoides and C. acutiventris could be used as proper bioaccumulators of MP pollution in the Danube River

Comparative Analysis of Classic Clustering Algorithms and Girvan-Newman Algorithm for Finding Communities in Social Networks

Nowadays finding patterns in large social network datasets is a growing challenge and an important subject of interest. One of current problems in this field is identifying clusters within social networks with large number of nodes. Social network clusters are not necessarily disjoint sets; rather they may overlap and have common nodes, in which case it is more appropriate to designate them as communities. Although many clustering algorithms handle small datasets well, they are usually extremely inefficient on large datasets. This paper shows comparative analysis of frequently used classic graph clustering algorithms and well-known Girvan-Newman algorithm that is used for identification of communities in graphs, which is especially optimized for large datasets. The goal of the paper is to show which of the algorithms give best performances on given dataset. The paper presents real problem of data clustering, algorithms that can be used for its solution, methodology of analysis, results that were achieved and conclusions that were derived. This work is licensed under a&nbsp;Creative Commons Attribution-NonCommercial 4.0 International License.</p

The anthropogenic impact on water quality of the river Danube in Serbia: Microbiological analysis and genotoxicity monitoring

The aim of this work was to examine the impact of urban wastewaters on the water quality of the Danube River in Serbia. Samples of water and sediments for microbiological analysis and genotoxicity monitoring were collected from 6 sites during spring and/or autumn 2010. Sanitary analysis, i.e. enumeration of total and fecal coliforms and intestinal enterococci, indicated moderate to critical fecal contamination, while organic load assessment (oligotroph to heterotroph ratio, index of phosphatase activity) revealed the category of moderately polluted water. Mercury-resistant bacteria were detected in all water samples, with high numbers at locations positioned downstream of Belgrade. There was no correlation of the microbiological parameters of the sediment and water samples. Genotoxicity monitoring, performed by the comet assay on hemocytes of mussels Sinanodonta woodiana, indicated a significant increase of DNA damage in mussels collected from the studied sites compared with the control group.Projekat ministarstva br. 173025 i br. 4300

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

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

First record of Bothrioneurum vejdovskyanum Štolc, 1886 (Oligochaeta, Tubificidae) in Serbia

We report the discovery of Bothrioneurum vejdovskyanum Štolc, 1886 (Annelida: Oligochaeta: Tubificidae: Rhyacodrilinae) in Serbian freshwaters. Fifteen specimens were found in the middle course of the River Ibar (southern Serbia), at a locality where the macrolithal type of substrate and strong currents prevail. These organisms were found together with Stylodrilus heringianus (Claparede, 1862). They were among the most abundant Oligochaeta species. The species are described and its biology and distribution are discussed. The present record contributes to the knowledge on the general distribution of this rare species, particularly in the Balkans (southeastern Europe)

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

The anthropogenic impact on water quality of the river Danube in Serbia: Microbiological analysis and genotoxicity monitoring

The aim of this work was to examine the impact of urban wastewaters on the water quality of the Danube River in Serbia. Samples of water and sediments for microbiological analysis and genotoxicity monitoring were collected from 6 sites during spring and/or autumn 2010. Sanitary analysis, i.e. enumeration of total and fecal coliforms and intestinal enterococci, indicated moderate to critical fecal contamination, while organic load assessment (oligotroph to heterotroph ratio, index of phosphatase activity) revealed the category of moderately polluted water. Mercury-resistant bacteria were detected in all water samples, with high numbers at locations positioned downstream of Belgrade. There was no correlation of the microbiological parameters of the sediment and water samples. Genotoxicity monitoring, performed by the comet assay on hemocytes of mussels Sinanodonta woodiana, indicated a significant increase of DNA damage in mussels collected from the studied sites compared with the control group.Projekat ministarstva br. 173025 i br. 4300