Planktonski žarnjaci Boka-Kotorskog zaljeva, Crna Gora (južni Jadran)

Planktonic cnidarians were investigated at six stations in the Boka Kotorska Bay from March 2009 to June 2010 by vertical hauls of plankton net from bottom to surface. In total, 12 species of hydromedusae and six species of siphonophores were found. With the exception of the instant blooms of Obelia spp. (341 ind. m-3 in December), hydromedusae were generally less frequent and abundant: their average and median values rarely exceed 1 ind. m-3. On the contrary, siphonophores were both frequent and abundant. The most numerous were Muggiaea kochi, Muggiaea atlantica, and Sphaeronectes gracilis. Their total number was highest during the spring-summer period with a maximum of 38 ind. m-3 observed in May 2009 and April 2010. M. atlantica dominated in the more eutrophicated inner area, while M. kochi was more numerous in the outer area, highly influenced by open sea waters. This study confirms a shift of dominant species within the coastal calycophores in the Adriatic Sea observed from 1996: autochthonous M. kochi is progressively being replaced by allochthonous M. atlantica in the coastal waters, especially in the eutrophicated areas. This study provides a detailed report on the composition and abundance of the planktonic cnidarians community in this region, and should be considered as a baseline for future studies on gelatinous zooplankton.Istraživanje planktonskih žarnjaka obavljeno je na šest postaja Boka-kotorskog zaljeva od ožujka 2009. do lipnja 2010. Uzorci su sakupljeni vertikalnim potezima planktonske mreže od dna do površine. Ukupno je nađeno 12 vrsta hidromeduza i 6 vrsta sifonofora. S izuzetkom velikih nakupina vrste roda Obelia u prosincu 2009. (341 jed. m-3), prosječne vrijednosti hidromeduza rijetko su prelazile vrijednost od 1 jed. m-3. za razliku od hidromeduza, sifonofore su bile češće i brojnije, osobito u proljeće i ljeto. Najbrojnije su bile Muggiaea kochi, Muggiaea atlantica i Sphaeronectes gracilis. Najveća gustoća od 38 jed. m-3 utvrđena je u svibnju 2009 i ožujku 2010. godine. Vrsta M. atlantica je dominirala u eutroficiranom unutrašnjem dijelu zaljeva, dok je M. kochi bila brojnija u vanjskom dijelu zaljeva koji je pod jakim utjecajem otvorenog mora. Naša istraživanja su potvrdila dosadašnja saznanja za Jadransko more da u obalnim, osobito eutroficiranim područjima, novo pridošla sifonofora M. atlantica postaje dominatna u odnosu na autohtonu vrstu M. kochi. Ova istraživanja donose prve detaljne podatke o sastavu i brojnosti planktonskih žarnjaka Bokakotorskog zaljeva i predstavljaju osnovu za buduća istraživanja želatinoznog zooplanktona

Neobična pojava jaja inćuna (Engraulis encrasicolus, Linnaeus 1758) u prosincu 2006. godine u Bokokotorskom zaljevu (Jadransko more)

Five anchovy (Engraulis encrasicolus, Linnaeus 1758) eggs were caught during an ichthyoplankton survey in Boka Kotorska Bay (south Adriatic Sea) with a PairOVET (modified CalVet) plankton net on December 5th, 2006. Eggs were found at two sampling stations (42°28’30.24” N, 18°44’41.81” E and 42°29’30.23” N, 18°40’41.84” E). It is the third record of anchovy eggs in the winter months in the Adriatic Sea.Pet jaja brgljuna (Engraulis encrasicolus, Linnaeus 1758) su uhvaćena tijekom istraživanja ihtioplanktona u Bokokotorskom zaljevu (južni Jadran) s PairOVET (izmijenjeni CalVet) i planktonskom mrežom 5. prosinca 2006. godine. Jaja su pronađena na dva mjesta uzorkovanja (42 ° 28’30 .24 “N, 18 ° 44’41 0,81” E i 42 ° 29’30 0,23 “N, 18 ° 40’41 0,84” E). Ovo je treći nalaz jaja brgljuna u zimskim mjesecima u Jadranu

Age, growth, and length-weight relationship of common nase (Chondrostoma nasus) in the Danube River near Belgrade (Serbia).

Growth parameters, length-weight relationship, and condition of the common nase (Chondrostoma nasus) in the Danube River near Belgrade were analysed on a sample (n=30) from the commercial catch, caught between March and May 2017. The total body length of the sampled individuals ranged from 26.8 to 40.1 cm, and body weight from 195 to 875 g. Age was determined from scales and individuals aged 5+, 6+ and 7+ were present in the sample, in approximately the same percentage. The regression coefficient of the length-weight relationship was b = 3.28. The value of b > 3 indicates a positive allometry, which denotes that the weight growth rate is greater than the length growth rate. The Fulton’s condition factor ranged from 0.90 and 1.36, with the mean value of 1.07. The parameters of the von Bertalanffy function were L∞ = 697.84, K = 0.08, and t0 = -1.72. The estimated phi-prime growth performance index (') was 4.60. The lengths were back-calculated using the method of Monastirsky, and the greatest relative growth increment was observed in the first and second year of life

Age, growth, and length-weight relationship of common nase (Chondrostoma nasus) in the Danube River near Belgrade (Serbia).

Growth parameters, length-weight relationship, and condition of the common nase (Chondrostoma nasus) in the Danube River near Belgrade were analyzed on a sample (n=30) from the commercial catch, caught between March and May 2017. The total body length of the sampled individuals ranged from 268 to 401 mm, and body weight from 195 to 875 g. Age was determined from scales and individuals aged 5+, 6+ and 7+ were present in the sample, in approximately the same percentage. The regression coefficient of the length-weight relationship was b = 3.28. The value of b > 3 indicates a positive allometry, which denotes that the weight growth rate is greater than the length growth rate. The Fulton’s condition factor ranged from 0.90 and 1.36, with the mean value of 1.07. The parameters of the von Bertalanffy growth function were L∞ = 697.84, k = 0.08, and t0 = -1.72. The estimated phi-prime growth performance index (j') was 4.60. The lengths were back-calculated using the method of Monastyrsky, and the greatest relative growth increment was observed in the first and second year of life

Growth parameters of vimba bream (Vimba vimba) in the Danube River near Belgrade (Serbia).

Age, growth, and length-weight relationship of the vimba bream (Vimba vimba) were analysed on a sample of 43 individuals from a commercial catch, caught between March and May 2017 in the Danube River near Belgrade. Total body length of the sampled fish ranged from 26.3 to 34.5 cm, and body weight from 223 to 554 g. Age of the sampled fish, determined from scales, ranged from 5+ to 8+, with the largest percentage of individuals in the age class 6+. The regression coefficient of the length-weight relationship was b = 3.28, which indicates a positive allometry. The parameters of the von Bertalanffy function were L∞ = 543.82, K = 0.09, and t0 = -2.41. The estimated phi-prime growth performance index (') was 4.44. The Fulton’s condition factor ranged from 1.04 to 1.42, with the mean value of 1.23. The length-at-age was back-calculated with the method of Monastyrsky, and the greatest relative growth increment was observed during the first two years of life

POREĐENJE DIVERZITETA I BROJNOSTI NASELJA RIBA U GLAVNOM TOKU I RUKAVCU DUNAVA KOD BEOGRADA (1168-1170 RKM)

Diverzitet i struktura naselja riba predstavljaju važne karakteristike dinamike akvatičnih ekosistema. Kako nastanjuju različita staništa i pripadaju različitim trofičkim nivoima, ribe predstavljaju jedan od najznačajnih elemenata za procenu ekološkog statusa akvatičnih ekosistema. Dunav u toku kroz Srbiju nastanjuje 68 vrsta iz 50 rodova i 16 familija (Simonović & Nikolić, 1997). Sastav faune beogradskog sektora Dunava karakteriše prisustvo oko 55 vrsta riba, od kojih oko 25 ima i ribolovni značaj (Hegediš et al., 2013). Važnu ulogu među njima imaju i alohtone vrste. Izgradnjom HE “Đerdap” dolazi do kritične ugroženosti ili nestanka anadromnih vrsta jesetri (fam. Acipenseridae). Što se biomase tiče, javlja se dominacija tzv. «bele ribe». Pored deverike (Abramis brama), značajan udeo imaju i rečna mrena (Barbus barbus), šaran (Cyprinus carpio) i jaz (Leuciscus idus) (ibid.). Cilj ovog rada jeste poređenje primenljivosti četiri indeksa diverziteta (Shannonov indeks, indeks ekvitabilnosti, Simpsonov i Margalefov indeks) u analizi raznovrsnosti naselja riba na beogradskom sektoru Dunava, između 1168 – 1170 rkm, u dve sezone (zima 2014. god. i proleće 2015. god.) i dva različita tipa staništa (otvorena voda na ušću Save u Dunav kod Velikog ratnog ostrva i rukavac Jojkića Dunavac). Indeksi diverziteta se koriste za kvantifikaciju raznovrsnosti zajednice, a njihove različite vrednosti mogu ukazati i na različit intenzitet antropogenog pritiska. Uzorci riba analizirani u ovom radu potiču iz komercijalnog ulova. Izvršeno je 10 uzorkovanja (po 5 u zimskom i prolećnom periodu). Uzorkovanje je vršeno mrežama (dužine 20-50 m, dubine 1,4 m i promera okaca 4, 4,5, i 5 cm). U uzorku koji je obuhvatio 747 jedinki identifikovano je 20 različitih vrsta riba iz pet porodica. Familija Cyprinidae, tzv. “bela” riba, ima najveću zastupljenost (preko 95%). Uočeno je postojanje razlike u sastavu naselja riba između ispitivanih lokaliteta. U mirnijim vodama Jojkića Dunavca prisutne su stagnofilne vrste, štuka (Esox lucius), bodorka (Rutilus rutilus) i grgeč (Perca fluviatilis). S druge strane, u otvorenoj i bržoj vodi oko Velikog ratnog ostrva zabeleženo je prisustvo reofilnih vrsta, kesege (Abramis ballerus), bucova (Aspius aspius), rečne mrene (B. barbus), skobalja (Chondrostoma nasus) i smuđa (Sander lucioperca). Vrednosti analiziranih indeksa pokazale su da je diverzitet vrsta ujednačen na oba lokaliteta. Na osnovu vrednosti Shannonovog indeksa, kvalitet vode na oba ispitivana lokaliteta varira između II-III i III-IV klase (umereno zagađene vode) u zavisnosti od sezone

ZDRAVSTVENO STANJE POPULACIJE CRNOG AMERIČKOG PATULJASTOG SOMA (AMEIURUS MELAS) U SAVSKOM JEZERU

Crni američki patuljasti som Ameiurus melas (Rafinesque, 1820) je jedna od najzastupljenijih i najuspešnijih alohtonih vrsta riba koja naseljava kopnene vode Evrope. Istraživanja koja su sprovedena u proteklih nekoliko godina ukazuju na to da je ovo dominantna invazivna vrsta i u mnogim kopnenim vodama u Srbiji, uključujući i Savsko jezero (Jaćimović, 2015). Zdravstveno stanje populacije crnog američkog patuljastog soma u Savskom jezeru procenjeno je na osnovu analize prevalencije i intenziteta parazitiranosti kod 2349 jedinki u uzorcima prikupljenim tokom 2011. i 2012. godine. Prevalencija parazitiranosti predstavljena je kao broj zaraženih jedinki, tj. procentualni udeo zaraženih jedinki, dok je intenzitet parazitiranosti predstavljen kao broj parazita u svakoj analiziranoj jedinki. Osim kod jedne jedinke kod koje je nađena cista Trematoda, svi uočeni endoparaziti pripadali su razdelu Nematoda. Najverovatnije se radilo o vrsti Philometra rischta. Zdravstveno stanje populacije tokom 2012. godine bilo je znatno bolje u odnosu na 2011. godinu. Jedinke starosti 3+ bile su najzaraženije endoparazitima, kako u svakoj pojedinačnoj godini, tako i u celom uzorku. Iako bi se moglo očekivati da nezaražene jedinke imaju veće vrednosti Fultonovog faktora kondicije (K) u poređenju sa zaraženim, rezultati istraživanja u Savkom jezeru pokazali su da takva pravilnost ne postoji

DUŽINSKO-TEŽINSKI ODNOSI I FAKTOR KONDICIJE KOD DEVERIKE (ABRAMIS BRAMA) U DUNAVU KOD BEOGRADA (1168-1170 RKM)

Deverika (Abramis brama) je značajna vrsta u privrednom i sportskom ribolovu i lovi se mrežama tokom cele godine. Koristi se i kao mamac pri ribolovu na grabljive ribe. Analizirani uzorci deverike potiču iz komercijalnog ulova obavljenog u periodu od decembra 2014. do februara 2015. godine na dva lokaliteta u Dunavu kod Beograda, Jojkića Dunavac (lokalitet 1) i ušće Save u Dunav (lokalitet 2). Uzorkovanim jedinkama izmerene su totalna dužina tela (TL) u mm i težina tela (W) u g, i određena im je starost očitavanjem naraštajnih zona na krljuštima. Korelaciona i regresiona analiza odnosa totalne dužine i težine tela urađena je kako za ceo uzorak, tako i za svaku uzrasnu kategoriju posebno. Za uzorke sa oba lokaliteta određeni su i Fultonov faktor kondicije (K = W/L3 x 100) i alometrijski faktor kondicije (C = W/Lb x 100). Srednja dužina tela (± SD) analiziranih jedinki iznosila je 242 ± 19 mm, a srednja težina (± SD) 151 ± 45 g. Starost jedinki kretala se od 1+ do 5+ godina. Najviše jedinki pripadalo je dužinskoj klasi od 231-260 mm i uzrasnim klasama 2+ i 3+, što znači da su u ulovu najviše zastupljene jedinke koje još nisu polno sazrele. Na taj način, onemogućeno je razmnožavanje ove ekonomski važne vrste ribe, a remeti se i dinamika brojnosti populacije, čime se smanjuje i ulov. Jedinke sa lokaliteta 1 pokazuju negativan alometrijski rast (a = 0.017, b = 2.85, r² = 0.86), dok jedinke sa lokaliteta 2 pokazuju pozitivan alometrijski rast (a = 0.004, b = 3.26, r² = 0.90). Prosečne vrednosti Fultonovog faktora kondicije bile su slične kod jedinki sa lokaliteta 1 (K = 1.04) i sa lokaliteta 2 (K = 1.05), dok su prosečne vrednosti alometrijskog faktora kondicije bile veće kod jedinki sa lokaliteta 1 (C = 1.70) nego kod jedinki sa lokaliteta 2 (C = 0.45). Rezultati su pokazali da kod uzoraka deverike sa oba lokaliteta najbolju kondiciju imaju jedinke koje pripadaju uzrasnoj klasi 4+ (sr. vr. K = 1.08 i C = 1.77 na lokalitetu 1; sr. vr. K = 1.11 i C = 0.47 na lokalitetu 2)

STATUS OF THE POTENTIALLY INVASIVE ASIAN SPECIES SCELIPHRON DEFORME IN EUROPE, AND AN UPDATE ON THE DISTRIBUTION OF S. CURVATUM (HYMENOPTERA: SPHECIDAE)

We reviewed the distribution of the two Asian species of the genus Sceliphron Klug, introduced into Europe in the late 1970s to early 1980s: S. (Hensenia) curvatum (Smith) and S. (Hensenia) deforme (Smith). Both species are routinely considered as invasive in Europe, but the status and effects of their (eventual) invasiveness are yet to be documented and evaluated. We had a focus on two areas, the Balkan Peninsula and European Russia, based principally on the study of specimens collected over the last 15 years, but we also reviewed the extensive published evidence (including some very important internet-based records), and for S. curvatum we provided a concise overview of the entire European range. We confirmed that the latter recorded species, S. deforme, has been introduced into Europe at least twice, first in the central part of European Russia, and then in the SW Balkans, and we established that these introductions originated from different source populations, belonging to a geographically widely separated Asian subspecies. Based on the most recent evidence, we confirmed successful establishment of S. deforme in both areas, and documented its ongoing spreading: from central European Russia southwards/southeastwards, and most probably from the Balkans eastwards. We rectified several erroneous country records for S. deforme (France, Italy, Bulgaria, Greece, “central Europe”), which have been extensively perpetuated in several important publications about the invasive species in Europe in the last three years (n.b. – for Greece, we have positively documented its presence only now). For S. curvatum, we added a new country record (Georgia/Abkhazia), and provided a few important earlier records from the Balkans (Serbia, Greece, Croatia, Bulgaria), which shift the timing of the previously published “first appearance” dates in the area (for two years for N Serbia and C Greece), or otherwise modify the knowledge of its history of spread. Since the most recent evidence suggests the rapid eastward advancing of both introduced species towards their respective westernmost/northernmost native range limits in western to central Asia, we considered it important to briefly review the state of knowledge about their possible coexistence in that area. We also provided detailed maps of their allochtonous ranges in Europe (currently exceeding the longitudinal span of 4,000 km) and westernmost part of their native ranges in Asia. Finally, we very briefly commented on some ecological aspects of their existence within the allochtonous range (parasitism, sex ratio, phenology)

Dnevni naraštajni prstenovi u otolitima i stopa rasta juvenilnog inćuna, Engraulis encrasicolus (Linnaeus, 1758), u jugoistočnom Jadranu

Daily growth rate of juvenile anchovy, Engraulis encrasicolus (Linnaeus, 1758), was estimated in the south-eastern Adriatic Sea. Samples were taken by a commercial beach seine net and the size range of 100 sampled individuals was 5.0-6.8 cm total length. Age was estimated by counting growth increments of sagittal otoliths, which are formed with daily periodicity. Estimated ages were 41- 90 days and hatch date for each age class was back-calculated from the date of capture. The calculated instantaneous growth rate was 0.41 mm day-1. Fish size at metamorphosis from late larva to juvenile was estimated to 3.2 cm total length. Parameters of the von Bertalanffy’s growth function were L∞ = 10.41 and K = 3.36Dnevna stopa rasta juvenilnog inćuna, Engraulis encrasicolus (linnaeus, 1758), procijenjena je u jugoistočnom Jadranu. Uzorci su sakupljani komercijalnom obalnom mrežom potegačom, a raspon veličine kod 100 uzorkovanih jedinki iznosio je 5.0-6.8 cm ukupne dužine. dob je procijenjena brojenjem dnevnih naraštajnih prstenova na sagitalnim otolitima. Procijenjena starost kolebala je između 41- 90 dana, a nadnevak izvaljivanja ličinke za svaki starosni razred bio je naknadno izračunat prema datumu ulova. Izračunata trenutna stopa rasta iznosila je 0.41 mm dan -1. Veličina ribe za vrijeme metarmofoze iz kasnog stadija ličinke u juvenilni stadij procijenjena je na 3.2 cm ukupne dužine. Parametri u von Bertalanffy-jevoj jednadžbi rasta bili su L∞ = 10.41 i K = 3.36