GENOTYPING OF ISOLATED VIRUSES FROM RAINBOW TROUT (ONCORHYNCHUS MYKISS) IN CROATIA

Infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV) are important pathogens in rainbow trout aquaculture. Detection of these viruses in Croatia initiated investigation of their genetic relatedness to the worldwide IHNV and IPNV isolates. For this purpose, determination of nucleotide sequences of G and NV genes for IHNV and VP2/NS region for IPNV was performed. Phylogenetic analyses revealed that Croatian IHNV isolate was clustering within European clade most closely related to the North American M genogroup. Croatian IPNV isolate appeared in the cluster of genogroup III, together with French, English, Danish and Norwegian isolates. These results are important for further epidemiological studies of IHNV and IPNV outbreaks in Croatia

ENVIRONMENTAL IMPACTS OF TUNA AQUACULTURE IN THE ADRIATIC SEA

Razvoj akvakulture, pa tako i tova tuna, u posljednjim je desetljećima, povećao zanimanje javnosti za moguće utjecaje na okoliš. Istraživanja utjecaja uzgoja gospodarski važnih ribljih vrsta su brojna, ali ne i u pogledu procjena mikrobioloških utjecaja, a napose ne u kontekstu tova tuna. Cilj ovog istraživanja bio je procijeniti utjecaj tova tuna (Thunnus thynnus) na okoliš na temelju praćenja mikrobioloških pokazatelja kakvoće morske vode na tovilištu tuna u srednjem Jadranu, te ostvarene rezultate usporediti s rezultatima istraživanja na tovilištu tuna u Mediteranu. Kakvoća morske vode analizirana je na dva lokaliteta, pri čemu je jedan lokalitet bio na tovilištu tuna, a drugi na udaljenosti oko 500m od tovilišta i poslužio je kao tzv. kontrolna točka. Uzorkovanje je provedeno u dvije sezone (proljeće/jesen), u 2007. i 2008. godini. Tijekom ovog istraživanja, analizirani su osnovni fizikalno-kemijski (temperatura, salinitet, prozirnost) i mikrobiološki parametri (ukupan broj bakterija, Vibrio, ukupni koliformi, Escherichia coli, fekalni koliformi, enterokoki) kakvoća morske vode. Za mikrobiološku analizu uzorci morske vode serijski su razrijeđeni s PBS otopinom (Merck). Za određivanje ukupnog broja heterotrofnih bakterija, uporabljene su metodom širenja razmaza dvije podloge, Marine agar (BBL) i Trypticase soy agar (BBL) s dodatkom 1% NaCl-a (Kemika), te supstrat metoda s uporabom SimPlate testa (IDEXX), sve u duplikatu. Za određivanje broja ukupnih koliforma i E. coli, odnosno enterokoka uporabljeni su supstrat testovi Colilert (IDEXX), odnosno Enterolert (IDEXX) u duplikatu. Utvrđene vrijednosti broja heterotrofnih bakterija, koje ukazuju na utjecaje tovilišta u vidu eutrofikacije mora, ukupno su manje od vrijednosti utvrđenih u istraživanjima poduzetim na tovilištima tuna u Mediteranu. Broj E. coli i enterokoka nije značajno različit između tovilišta i kontrolne točke, ali su te vrijednosti veće u odnosu na dosadašnja istraživanja na sličnim tovilištima u Mediteranu. Povećani broj enterokoka u uzorcima mora, i oko tovilišta, najvjerojatnija je indirektna posljedica nepravilne tehnologije hranidbe, koja privlači kolonije galebova. Ovi rezultati ukazuju da promjene kakvoće morske vode, a u svezi s tovom tuna, ovise o širem ekološkom kontekstu. Stoga, smještaj i procjenu utjecaja tova na okoliš valja razmatrati u sklopu šireg ekološkog konteksta područja.Aquaculture including tuna fattening, increased public interests in the possible impact on the environment in recent decades. Influences of cultivation of economically important fish species are numerous, but not in regard to assessment of microbial influences, particularly in the context of tuna. The aim of this study was to assess the effects of tuna fattening (Thunnus thynnus) in the sense of the environmental monitoring of microbial indicators of seawater quality at tuna farm in the central Adriatic, and to compare the achieved results with the results of research on a tuna farm in the Mediterranean. The quality of sea water was analyzed at two sites; one site was at the tuna farm, and the other at a distance of about 500m from the farm, the control point. Sampling was conducted in two seasons (spring / autumn), in 2007 and 2008. During this study, the basic physico-chemical (temperature, salinity, transparency) and microbiological parameters of seawater quality (total number of bacteria, Vibrio, total coliforms, Escherichia coli, faecal coliforms, enterococci) were analyzed. For microbiological analysis of seawater; samples were serially diluted with PBS solution (Merck). To determine the total number of heterotrophic bacteria, spread plate method was used on Marine agar (BBL) and Trypticase soy agar (BBL) supplemented with 1% NaCl-a (Kemika), as well as substrate method using SimPlate test (IDEXX), all in duplicate. To determinate total coliforms and E. coli, and enterococci substrate tests Colilert (IDEXX) and Enterolert (IDEXX) were used in duplicate. Number of heterotrophic bacteria, which indicate the effects of the farm on the eutrophication, was less than the number determined in similar study in the Mediterranean. Number of E. coli and enterococci were not significantly different between farm and control point, but these values are higher than those from research in the Mediterranean. Increased numbers of enterococci, on the farm and control point, were indirect consequence of improper nutrition technology, which attracted a colony of seagulls. These results suggest that changes in seawater quality in relation to tuna fattening, depend on the broader ecological context. Therefore, location and environmental impact of tuna fattening on the environment must be considered within the broader context of ecological areas

HEALTH STATUS OF CHUB (Squalius cephalus) IN RELATION TO WATER QUALITY OF SAVA RIVER

Voda kao životni okoliš organizama koji u njoj žive svojom kvalitetom utječe na njihovo zdravstveno stanje. U dostupnoj je literaturi malo podataka o pokazateljima zdravstvenoga stanja klena, osobito iz rijeke Save. Zbog toga je svrha ovog istraživanja bila procijeniti zdravstveno stanje klena kao pokazatelja kvalitete vode, te odrediti odnos histoloških i parazitoloških pokazatelja prema broju bakterija u vodi. Istraživanje je provedeno na ukupno 289 klenova s pet postaja od slovensko–hrvatske granice do utoka rijeke Une u Savu. Uzorci organa klena uzeti su za parazitološku i histološku pretragu. Istodobno je uzorkovana voda i određen broj heterotrofnih i koliformnih bakterija. Razlike u količini bakterija u vodi bile su izražene među pojedinim postajama. Najviša je vrijednost utvrđena na postaji Oborovo, a najniža na postaji Otok Samoborski. Intenzitet histoloških promjena bio je u korelaciji s mikrobiološkom kakvoćom vode. U svim uzorkovanim organima utvrđen je barem jedan histološki pokazatelj u visokoj korelaciji s mikrobiološkom kakvoćom vode. Od parazitarnih invazija samo su ihtioftirijaza i trihodinijaza pokazale visoku negativnu korelaciju s mikrobiološkom kvalitetom vode. U sklopu parazitološke pretrage primijenjivane su i molekularne metode u svrhu identifikacije crijevnih parazita iz grupe Acanthocephala.Water quality has infuence on the health status of the organisms living in it. In the available literature, there is only a few reports on the health status of chub, particularly in the Sava river. The aim of this study was to estimate health status of chub as indicator of water quality. Furthermore we aimed at relating fish histology and parasitology to the number of bacteria in the water. We sampled 289 chubs for parasitological and histological examination. Fish were sampled on five sites from slovenian–croatian border through to the inflow of river Una in Sava. At the same time, water was sampled for the counting of coliforms and heterotrophic bacteria. The difference in the number of bacteria in the water was pronounced at different locations, with Oborovo and Otok Samoborski having the highest and the lowest values respectively. The intensity of histological parameters was in correlation with the number of bacteria in water. At least one histological parameter highly correlating with the water quality was found in every organ. Regarding parasite invasions, only ichthyophthiriasis and trichodiniasis showed high negative correlation with microbiological quality of the water. As part of parasitological examination, molecular methods were used for the identification of Acanthocephala

BACTERIOLOGICAL PROPERTIES OF MARINE WATER IN ADRIATIC FISH FARMS: ENUMERATION OF HETEROTROPHIC BACTERIA

Akvakultura je jedna od grana proizvodnje hrane, s izuzetnim razvojem. Povećana primjena hrane u akvakulturi, uz moguće organsko onečišćenje generalno vodi ka narušavanju kvalitete vode. Problemi narušene kvalitete vode vezani su uz fizikalne i kemijske čimbenike, kao i narušavanje mikrobiološke kvalitete vode. Heterotrofne bakterije imaju značajnu ulogu u procesu razgradnje organske tvari u vodenom okolišu i pokazatelj su procesa eutrofikacije. U ovom su radu prikazana naša iskustva i spoznaje o bakteriološkim svojstvima morske vode u uzgajalištima lubina (Dicentrarchus labrax L., 1758) uzduž istočne obale Jadranskog mora, s ciljem određivanja broja heterotrofnih bakterija u morskoj vodi primjenom dvije metode i dvije temperature inkubacije. Primijenjene su dvije metode za prebrojavanje heterotrofnih bakterija u morskoj vodi: supstrat SimPlate® test i metoda širenja uzorka po podlozi s uporabom uobičajenih umjetnih hranjivih podloga (Marine agara i Tryptic Soy agara s dodatkom NaCl), kao i dvije temperature inkubacije (22ºC i 35ºC). Rezultati analize bakterioloških svojstava morske vode u jadranskim uzgajalištima upućuju da je određivanje broja heterotrofnih bakterija u morskoj vodi ovisno o primijenjenoj temperaturi i mediju za brojanje. Pri tome je temperatura inkubacije od 22°C pogodnija za rast heterotrofnih bakterija iz morske vode, a SimPlate test daje veće vrijednosti broja heterotrofnih bakterija. Rast vrijednosti broja heterotrofnih bakterija tijekom istraživanja upućuju na moguće narušavanje mikrobiološke kvalitete morske vode u jadranskim uzgajalištima te na potrebu redovitog monitoringa kvalitete morske vode.Aquaculture is currently one of the fastest growing food production sectors in the world. Increase in nutrients and organic wastes lead to general deterioration of water quality. The problem of water quality is associated with both physical and chemical factors, as well as microbiological water quality. Heterotrophic bacteria play an important role in the process of decomposition of organic matter in water environment and indicate eutrophication process. Here we present our experience and knowledge on bacterial properties of marine water in the Adriatic fish farms with European sea bass (Dicentrarchus labrax L., 1758), with an emphasis on enumeration of heterotrophic bacteria in marine water. We applied two temperatures of incubation, as well as two methods for enumeration of heterotrophic bacteria: substrate SimPlate® test and spread plate method on conventional artificial media (Marine agar and Tryptic Soy agar with added NaCl). The results of analysis of bacteriological properties of marine water in the Adriatic fish farms showed that enumeration of heterotrophic bacteria in marine water depends on the applied incubation temperature and media for enumeration. At the same time, the incubation temperature of 22C favours more intense growth of marine heterotrophic bacteria, whereas a SimPlate test gives higher values of heterotrophic bacteria. Volatile values of heterotrophic bacteria during this research indicate a possible deterioration of microbiological water quality in the Adriatic fish farms and a need for regular monitoring of marine water quality