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The quality of oyster meat shows a seasonal variation which is mainly influenced by spawning season, as well as by relevant environmental factors such as hidrographic parameters and the availability of food. It can also be affected by diseases and eventual water pollution (Ruiz et al., 1992 ; Austin et al, 1993 ; Gavrilović et al., 2008). One of the common methods for the evaluation of oyster quality is a determination of meat index (MI) according to Fleury et al. (2003). Following this method, in France which is the highest consumer of oysters in the world, this sea food product is classified into three categories: „spéciales“ (MI > 10, 5), „fines“ (MI 6, 5 – 10, 5) and „non – classées“ (MI < 6, 5). This paper describes the combined effects of different factors on the quality of cultivated european flat oyster Ostrea edulis in the Bistrina Cove, located in the Bay of Mali Ston, the location of the highest shellfish production level in Croatia. At the beginning of the experiment (January 2009) 1500 oysters of approximately the same size were selected and cemented on the nylon ropes (35 oysters per one rope) following local traditional farming techniques. Ropes were deployed on floating long-lines in the Bistina Cove in the Mali Ston Bay. Oysters were placed between one and four meters deep. A sample of 30 specimens was taken for the MI calculation each month during the one year period, together with water samples for the determination of the seston quantity parametars (total – TPM, inorganic – PIM and organic particulate metter POM). Mean monthly value of the hidrografic parametars were calculated according to a weekly measurement, where salinity and temperature were measured with a WTW Cond 315i/SET probe, pH with HANNA instrument HI 8424, and oxygen saturation with the OxyGuard Handy Polaris HO1P. For the quality of oyster meat, the MI was determined according to Fleury et al. (2003) with the formula: wet meat weight / total shellfish weight x 100. Seston quantity parameters (TPM, PIM, POM) were analyzed according to the method described by Peterson et al. (2003). According to the monthly values of the MI, oysters were classified following the categorization described by Fleury et al. (2003). Pearson correlation coefficients were calculated in order to determine the relationship between MI and each particular environmental parameter. The examination of the correlation between MI and all environmental parameters was calculated by multiple regression analysis (Zar, 1999). Results and discussion Figure 1. shows the monthly variations of MI. The highest value was recorded in April, followed by a decrease to the minimal recorded value in August. During the autumn months the value slightly increased until November. These variations coincided with the gonadal maturation seasons which occur two times per year in this aquatoria (Gavrilović et al., 2008). Fig. 1. Monthly variation of meat index of O. edulis in the Bistrina Cove A yearly average value of 12, 38 and the fact that oysters from this location belong in the category „spéciales“ for ten months in the year (only in August and September they were categorized as „fines“), leads to the conclusion that this location has favourable conditions for oyster cultivation. The French (IFREMER' s) method of monitoring (Fleury et al., 2003) at different locations resulted in MI values ranging from 6, 6 to 14, 6. Oysters at different farming location in Mali Ston Bay (Otok Života – Usko) were categorized as „spéciales“ for seven months in the year (Gavrilović et al., 2008). Correlation coefficients between MI and temperature showed a strong negative correlation (r=-0, 54). The relationship between MI and salinity (r=0, 32), TPM (r=0, 11) and POM (r=0, 14) were very low positive, while there was no correlation for POM (r=0, 01). MI and salinity had a very low positive correlation (r=0, 23), while there was a very low negative correlation between MI and oxygen saturation (-0, 11). According to the results of multiple regression analysis, the relationship between MI and all measured variables can be described by the following formulas: MI=-0.33*Month-0.15*T°C-0.02*Sal-0.07*O2+ 3.18*pH-93.65*TPM (r2=0, 99) MI=-0.447*Month-0.110*T°C+ 0.128*Sal-0.053*O2 + 2.414*pH+ 12.339*PIM-689.371*POM (r2=0, 99).

Indigenous populations of brown trout (Salmo trutta L.) throughout Europe have been seriously affected by environmental degradation, harvest and enhancement and are constantly decreasing. Brown trout is classified as a vulnerable species according to the Croatian Red List. Croatia’s Gacka River is one of the most fascinating karstic rivers in Croatia ; it is a part of the Adriatic drainage and among the best-known trout sites in the world. Brown trout in Gacka River grows faster than in other karstic rivers, owing particularly to the optimal water temperature with minor oscillations, plenty of oxygen and the water’s mildly alkaline chemical structure. During the past three decades, the river has been managed by several administrations, which occasionally maintained poorly documented stocking activities. Although stocking was generally regarded as a main tool in the conservation and enhancement of fish populations, today it is well known that inappropriate stocking is a threat to the genetic integrity of wild populations. The importance of the project lies in the preservation of indigenous brown trout of verified genetic profile and the possibility of stocking Gacka River with native, genetically authenticated phyilogenetic lineages of fish in its natural habitat thus creating the conditions for a richer offer through development of fishing tourism of already well-known trout river. The project relies on the construction of the basic infrastructure for breeding of captured indigenous brown trout, taking into account the priorities of environmental protection and sustainable socio-economic development. Indigenous spawners were fished out, checked for the presence of pathogens, their sexual products genetically analyzed, and authenticated lineage produced from eggs to fry size suitable for stocking and further growing. The project thus has direct impact on the following: - preservation and breeding of endangered lineages of brown trout, - controlled stocking with bred, genetically verified fish with checked health status, - potential for providing a high quality offer for brown trout sport fishing, - increased possibilities for a quality offer of brown trout as a culinary specialty, - increase in the overall quality of the tourist offer in the region, - greater awareness for the importance of preserving a clean environment, - new conditions for creating new jobs through employment in the breeding center and self-employment related to the work and development of the centre, - increased global recognition of the region and Croatia as a breeding center for indigenous species. The center is the only of its kind in the wider region that combines breeding facilities with scientific research. An entire component of the project is dedicated to the improvement of skills and know-how in the field of business management and fish breeding technology. Therefore, apart form protecting it from extinction, the model is developed for the rehabilitation and breeding of the brown trout, applicable in other regions and countries.

Ceratothoa oestroides is a cymothoid parasite of cage-cultured sea bass. The adult female and male parasites settle in the buccal cavity of fish. It is a nonspecific host fish parasite with records in six different fish families but no records in wild sea bass. Their life cycle involves only one host. It is considered as one of the most threatening parasitic diseases in Croatia with a high economic impact. A three-year health status monitoring of cultured sea bass was carried out in this study. A total of 1154 parasited sea bass from the same population was examined. Six samplings per year in the first two years were conducted. In the third year, 24 samplings were performed only during winter and summer. Result showed significant very high positive correlation between length and weight of host fish and parasite length during the first year while high positive correlation was found in the second year between the same biometric measures. During the winter period in the third year, the length of female parasites was in a low positive correlation with the length and weight of parasited fish while in the summer period the length of female parasites was in a moderate positive correlation with the length and in a low positive correlation with the weight of host fish.

Freshwater crayfish of the family Astacidae (phyllum Arthropoda, order Decapoda) are represented with more than 540 species in Europe and four of them are indigenous in Croatia: Astacus astacus (Linnaeus, 1758) or noble crayfish, Astacus leptodactylus (Eschscholtz, 1823), Austropotamobius torrentium (Schrank, 1803) or stone crayfish and Austropotamobius pallipes (Lereboullet, 1858) or white-clawed crayfish. Three species (noble, stone and white-clawed crayfish) are listed in the IUCN Red List of Threatenes Species as vulnerable (VU) and are protected by the Croatian law ; the Law of Nature Conservation and the Rule Book on Protection of Crayfish. Also, the presence of one nonindigenous species (Orconectes limosus) was confirmed in marshes of the Nature Park Kopački rit, Croatia.

The frequencies of erythrocytic nuclear abnormalities (ENA), micronuclei (MN), vacuolated nuclei (VN) including cytoplasmic vacuoles (CV) were monitored in the peripheral blood of cultured shade fish Argyrosomus regius (Asso, 1801). Sampling was performed through three seasons: at the end of the winter (March), spring (May) and summer (July) at one location from southern Adriatic Sea (Croatia). ENA comprised blebbed, lobed and notched nuclei, which were the most frequent features, while the MN, VN and CV appeared sporadically. The highest level of ENA and MN were detected in July, and VN in March, respectively. The rarest appearance of these parameteres were recorded in May. Inversely, cytoplasmic vacuoles were the most frequent in May and the least in July. The Spearman rank order correlation test revealed a significant positive correlation between the frequencies of ENA and MN (P < 0.05, r = 0.44), ENA and VN (P < 0.05, r = 0.56). Also, the frequency of MN significantly positively correlated with water temperature (P < 0.05, r = 0.42) and negatively with level of oxygen (P < 0.05, r = - 0.42). Cytoplasmic vacuoles did not correlate with any measured parameters. Our results demonstrate that these parameters displayed a distinct seasonal variation.

Fresh seafood (fish, shellfish, crustaceans, molluscs) were randomly selected and collected from the biggest inland market in Croatia in warm and cold season of the year and they were examined for presence of V. parahaemolyticus and enterobacteria through winter and summer seasons. Consumption of raw or undercooked seafood, particularly shellfish, contaminated with V. parahaemolyticus may lead to development of acute gastroenteritis characterized by diarrhoea, headache, vomiting, nausea, abdominal cramps and low fever. The Enterobacteriaceae count is considered as one of the indexes of fish quality because it is related to storage under ice, washing and evisceration. Unacceptable Enterobacteriaceae levels were obtained in 40 % of the summer fish samples. The poorest quality regarding high counts of enterobacteria was found for summer molluscs and fish, respectively, with up to 3x103 CFU/g. The overall prevalence of V. parahaemolyticus was 5 %. The recovery rate was higher in shellfish in both seasons than in other specimens or specific season conditions. The ubiquitous nature of Vibrio species in marine and estuarine environments makes it impossible to obtain seafood free of these bacteria. The significance for public health is dependant on the health status of the consumer as well as on the concentration and on the pathogenicity of bacteria. Seafood consumers should be acquainted with possible health hazards related with the consumption of raw or undercooked seafood, especially shellfish since careful handling of seafood, prevention of cross-contamination at the processing or food preparation are crucial in preventing infections associated with seafood pathogens.

Brown trout (Salmo trutta L.) has a widespread distribution across Europe. It is characterized by a complex genetic structure and high genetic population differentiation throughout its distribution. Based on the sequence variation of the mitochondrial (mt) DNA control region, five major evolutionary lineages were proposed: Atlantic, Danubian, Adriatic, Mediterranean and marmoratus. However, some regions remain understudied and there is still a deficiency of data from particular areas of the brown trout native range. One such understudied area with importance to the evolutionary history of the species is Croatia. Individuals originating from the Plitvica River were investigated. In order to assess phylogenetic lineages affiliation, and address the question of autochthony of population in the river, mtDNA control region variations were analysed. Complete sequencing of the mtDNA control region revealed that all sampled individuals possess the same haplotype. Identified haplotype was a new, previously undescribed haplotype belonging to the Danubian lineage. Phylogenetic analysis with other Danubian haplotypes demonstrated that this new Danubian haplotype was most closely related to the Da9 haplotype. Thus, this novel haplotype has been named Da9a. It was concluded that brown trout population from the Plitvica River represent native population and should be protected from introduction of domesticated strains of brown trout.

nema sazetka, opisana je uporaba antimikrobnih lijekova koje je MPRRR odobrilo za uporabu na ribama u RH, kao i onih koji se kroz praksu koriste, a koji su odobreni za druge vrste životinja.

Plasma biochemical profile was examined in cage cultured shade fish Argirosomus regius in order to evaluate physiological profile and provide detailed picture of its seasonal changes. Biochemical procedures were employed to study trygliceride (TRIG), cholesterol (CHOL), total protein (TP), glucose (GLU), urea (BUN), inorganic phosphate (PHOS), calcium (Ca), creatine kinase (CK), lactate dehydrogenase (LDH), ammonia (NH3), magnesium (Mg), aspartate aminotransferase (AST), amylase (AMYL), alkaline phosphatase (ALKP), creatinine (CREA), gamma glutamyltransferase (GGT) and total bilirubin (TBIL). The results were evaluated through different statistical analyses. Conventional statistical methods do not provide solutions that meet the goals of the research, so machine learning methodology was used to construct and evaluate classifiers as well as to assess parameter (plasma metabolites and enzymes) importances with respect to the target variable (season). It is evident that about half of the parameters (UREA, ALKP, NH3, CHOL, Ca, PHOS, GLU and CREA) have significant importance (i.e. exhibit significant differences between seasons) for seasonal discrimination models. It is also important to stress that using only a subset of most important parameters is generally enough to obtain high accuracy classifiers, which suggests rather high correlation between these parameters on a seasonal scale.

Molecular genetic studies of brown trout Salmo trutta L. throughout its natural range have demonstrated five major phylogenetic lineages. Such studies have revealed that the species is genetically and geographically highly structured. It is especially important for highly structured species, such as brown trout, that conservation activities are focused at population level. The brown trout population from the Krka River represents the natural population of brown trout from a poorly studied area of south-east Europe. A 562 bp fragment at the 5’ end of mitochondrial DNA control region was sequenced from the population representatives and compared to corresponding brown trout sequences obtained in previous studies. Sequence analysis of the mtDNA control region of brown trout from the Krka River revealed the existence of four major phylogenetic lineages. The native status is assigned to the Adriatic, Mediterranean and marmoratus lineages, while the presence of the Atlantic lineage is a consequence of stocking practice. The results of this study show that brown trout population in the Krka River possesses a unique genetic profile that should be taken into account in future conservation strategies.

nema sažetka

Recovery of Aeromonas hydrophila from the liver, kidney and spleen of screened mullet was described in this work. Affected fish did not manifest external signs of disease, while necropsy findings revealed haemorrhages from the liver, and posterior kidney.

The purpose of this study was the identification and quantification of biochemical parameters over a 1-year cycle and to provide a detailed picture of seasonal changes in plasma metabolites and enzymes. Using the novel methods of machine learning techniques, the authors created and generated for the first time comprehensible classification models for exploring the importance of blood chemistry parameters, strength, mutual interactions or dependencies, and reliability of particular parameters within the seasonal groups.

Extensive lesions, skin ulcers, exophthalmia and ascitic fluid are described in carp fingerlings upon onset of Aeromonas hydrophila infection.

The available data concerning rapid identification of fish bacteria via commercial phenotypic tests demonstrate that there is no agreement regarding the choice of selection of the tests. However, API 20E, an identification system for Enterobacteriaceae and other non-fastidious Gram-negative rods developed for clinical specimens, seems to be increasingly used for the identification of fish pathogens. In this work, adaptation of API 20E for fish bacterial isolates and its distinctiveness for fish bacteria was assessed. For some bacterial fish isolates, their identification must be regarded as only presumptive. Some strains are wrongly identified because they are not included in the database of API 20E system. For comparable results, API 20E has to be adapted for bacterial fish isolates, and there should be a consensus among the fish health professionals regarding the incubation temperature and the duration of the incubation time before performing readings. API 20E reactions should be compared with the diagnostic schemes based on reactions in conventional phenotypic tests. Due to their significance for fish health and impact on the aquaculture, and because of the need for their rapid identification, some important fish bacteria should be included in the API 20E system, such as Yersinia ruckeri, Edwardsiella ictaluri, Vibrio anguillarum.

U predavanju su predstavljeni rezultati dvogodišnjeg mjerenja i istraživanja fizikalno-kemijskih parametara vode rijeke Gacke, te su prikazane usporedne vrijednosti prema postajama.

The brown trout is the most widely distributed fish specied native to Eurasia and North Africa. However, the species has also been extensively introduced worldwide, mailnly for fishing reasons. In the past two decades, genetic variation of brown trout has been extensively studied throughout its natural range. Such studies have demonstrated five distinct phlogenetic lineages defined by mitochondrial DN control region sequences.Established haplotypes in Plitvice lakes were assigned to both Atlantic and Danubian phylogenetic lineages.

Genetic variation of brown trout, Salmo trutta L., has been extensively studied throughout Europe. Such studies have demonstrated five distinct phylogenetic lineages defined by mitochondrial DNA (mtDNA) control region sequences. Croatia is an important geographic region where no systematic studies of genetic variation have been made. MtDNA control region variation from 9 individuals originating from Gacka River were analysed, in order to assess their phylogenetic lineages affiliation, and address the question of autochthony of populations in the river. Based on a sequencing of the 334 bp fragment at the 5' end of the mtDNA control region, two haplotypes were identified. Although Gacka River is a part of the Adriatic drainage, 4 individuals (45 %) were assigned to Atlantic haplotype Ad1 and 5 individuals (55 %) were assigned to Danubian haplotype Da2. The presence of Atlantic and Danubian haplotypes primarily reflects introgressioon stemming from the stocking of hatchery-reared fish, although natural status could not be excluded. These results are of great importance for future adequate management and conservation of natural brown trout populations in this region.

The blood plasma of reptiles is a colourless or greenish - yellow to orange fluid, depending on the species. It comprises some 60 to 80 per cent of the blood volume. The plasma contains a great variety of different substances, most of them present in trace quantities. The composition of blood plasma shows a great variation in reptiles. There are no strictly basal conditions to define reference values in reptilian physiology. The data on seasonal measurements of haematological parameters are scarce, and so are the reference values involving the plasma biochemistry annual cycle. Balkan whip snake (Hierophis gemonensis) is one of most common snakes of costal Croatia and its islands. The results we have shown here consider some plasma biochemical values of captive Balkan whip snakes, in controlled enviroment Measured plasma biochemical parameters were: total protein, glucose, cholesterol, urea, triglycerides, AST, LDH, CK, ALP, calcium and phosphorus. The aim of this study is to determine haematological and biochemical reference ranges in blood for Balkan whip snake. These results could be used for better understnding of reptilian hematology.

U predavanju su opisane značajne nezarazne vrste bolesti pastrvskih vrsta riba koje se pojavljuju prilikom intenzivnog uzgoja, a odnose se uglavnom na fizikalno-kemijske uvjete , te tehnologiju uzgoja.

The usefulness of mammalian antibodies for piscine P450 Western blotting was demonstrated. Also, hepatic P450 1A2 and 3A4 metabolism was quantifiable by modifying kits developed for mammalian microsomes.

Za razliku od eritrocita sisavaca, riblji eritrociti posjeduju jezgru. Osim eritrocita sa ovalnom jezgrom, u krvotoku riba se mogu pojaviti i eritrociti s nepravilnim oblicima jezgri. Međutim mehanizam nastanka tih promjena nije razjašnjen niti je usaglašeni stav o uzroku tih promjena. Istraživanje je pokazalo da se pojava nepravilnih oblika eritrocitnih jezgri riba ne može tretirati kao isključiva posljedica genotoksičnih djelovanja, virusnih infekcija ili kao specifičnost vrste, već postoji niz različitih etioloških čimbenika koji dovode do takvih promjena, a mehanizam nastanka tih promjena vjerojatno je u osnovi isti.

Svi testovi za brzu identifikaciju bakterijskih izolata razvijeni su mahom za identifikaciju bakterija iz porodice Enterobacteriaceae ljudi i toplokrvnih životinja. Oni mogu biti vrlo korisni za dijagnosticiranje nekih bakterija iz riba, iako neke od njih nisu uključene u bazu podataka tih sustava. U njihovom korištenju potreban je oprez zbog mogućih pogrešnih interpretacija, a korišteni testovi u ovom radu davali su proturječne nalaze oko identifikacije Vibrio vulnificus izolata, stoga se preporuča korištenje konvencionalnih metoda uz svaki brzi test.

The aim of the study was to observe the influence of different ploidy levels in fish on micronucleus occurence. Twenty minutes after fertilization, one group of rainbow trout eggs was exposed to water temperatures of 26C in duration of 20 minutes to induce triploidy. Second group was kept in water temperature of 10C, which is optimal for development of rainbow trout. The frequency of micronucleated erythrocytes was determined in the peripheral circulation of rainbow trout 67 days (following absorption of the yolk - swim-up stage) and 128 days (fry stage) post fertilization. There was a significant difference (P

The impact of two aquaculture antibiotics, Terramycin for Fish (oxytetracycline) and Romet-30 (combination of ormetoprim and sulfadimethoxine), on hepatic microsomes of hybrid striped bass, summer flounder, tilapia and channel catfish was assayed. Fish were treated via medicated feed and samplings were performed on day 1, 6, 10/11, and 21 after termination of treatment. Western blotting analyses were performed with mammalian primary antibodies, goat anti-rat CYP1A1 and rabbit anti-human CYP3A4, to demonstrate the possibility of their application in piscine immunochemical assays. Kinetic assays with substrates developed for humans were used: 3-cyano-7-ethoxycoumarin (CEC), /-benzyloxy-4-triflouromethylcoumarin (BFC) and resorufin benzyl ether (BzRes), CES being a CYP1A2 substrate, while BFC and BzRes being CYP3A4 substrates. The results demontrate presence and putative induction of CYP1A and CYP3A enzymes in all sampling periods. Both goat anti rat CYP1A1 and rabbit anti-human CYP3A4 showe good cross-reactivity with the four fish species tested in the study, with a number of non-specific binding. In majority of blots, two immunoreactive bands were displayed. Both antibiotics induced CYP expression in all tested fish, although with different intensities in band signals. Clear responses were found in the hepatic xenobiotic metabolizing enzyme system of four different fish species in a directly comparative manner with differences both in control activities and in the timing and extent of induction responses. BzRes showed to be a better substrate than BFC for monitoring CYP3A activities in fish. Age influenced the pattern of activity in tilapia microsomes after treatment wth Romet-30. While young of the year fish had increased activities of CEC and BzRes in day 1, immature tilapia had all three measured activities decreased below control levels. Summer flounder males displayed slightly stronger signal in Western blots and higher BFC activity, while females had higher activity of CEC and BzRes. In channel catfish treated with Romet-30, there was an apparent increase of CYP3A-related protein acitivity manifested through both BFC and BzRes activities, which suggests that channel catfish may be a good model for investigating the regulation of those proteins. It can be concluded that the use of antibiotics and substrated to CYP enzymes across phyla can be of value of caution is excercised and that standardized protocols for antibiotic impact on fish P450 are necessary for the future application on teleosts.

Health status of rudd living in the biggest Croatian carstic lake is evaluated. Studies were conducted during a two-year period and comprised of parasitological, haematological and bacteriological surveys. Parasitological examination revealed a light infestation on 27 % of examined fish, mostly with Dactylogyrus and Ichthyophthirius species. Haematological studies showed that haematocrit values were lower than physiological limit. A haematocrit coefficient of correlation was in all research periods higher than 15 %, indicating that majority of fish under study were susceptible to development of bacterial and other diseases. Indeed, a diverse array of bacteria were isolated from rudd, mainly Flavobacterium spp. and Aeromonas spp., but also some specific fish pathogens, notably Pasteurella piscicida, Yersinia ruckeri and Edwardsiella ictaluri. Under stress conditions, detected bacterial species can give rise to disease outbreaks.

Air traffic legislatives and measures for air transport of domestic and wild animals are described. Possible impact of transport-related stress on animal health is described.

Aeromonas hydrophila was recovered from fish living in lake Vrana on the Croatian island of Cres. The occurence of the bacterium in the fish was assessed and related to gross signs of disease and findings at necropsy as a potential health hazard for fish. Isolated bacteria were subjected to morphological, physiological, biochemical and antibiotic susceptibility tests. A total of 26 A. hydrophila isolates were obtained. There was a clear seasonality, as no isolates were recovered in the summer months. Most of the isolates were sensitive to all the antimicrobials used in the study except novobiocin and penicilling G. Affected fish manifested haemorrhages over the skin, in the liver, kidney and swim bladder, spleen infarcts, fatty liver, ascitic fluid and swollen haemopoietic tissues. A. hydrophila does not appear to pose a major threat for the fish in the lake at present but under unfavourable and stressful conditions it could seriously compromise fish health.

Abiotic stress in aquarium is a likely contributor to outbreaks of diseases due to immunosupression or increased vulnerability. Extensively reared carp fingerlings transported from earthen ponds to aquarium were exposed to multiple abiotic stressors. These stressors reduced resistance and challenged disease. Severe mortalities occurred and fish started to exhibit signs of septicaemic disease accompanied with skin erosion. Upon the beginning of mortalities a complete necropsy examination, as well as parasitological, virological and bacteriological evaluations were performed on dead and moribund fish. After necropsy and bacteriological examination the occurrence of motile aeromonad septicaemia (MAS), a bacterial disease caused notably by Aeromonas hydrophyla, was established. The role of abiotic stresses, including fish manipulation and water quality, were discussed regarding the disease outbreak. Prospective methods to minimize the risk of diseases as well as their limitations were presented.

One of the major problems of water pollution is the capability of pollutants to concentrate in aquatic organisms.Bioaccumulation and bioconcretration of such chemicals in fish render in unsuitable for human consumption. Bioconcretration of water pollutants through algae, zooplankton and other organisms, can lead to their accumulation through foo-chain, with the fish at the top of the pelagic food web. The occurence of elevated residue levels of various xenobiotics with increasing trophic level hasbeen demonstrated in a variety of aquatic environments and organisms.The increased bioconcretation occurs with increasing trophic level.The tendency of a chemical to bioconcretate has been shown to be strongly related to its lipophilicity. Trophic-level differences in bioconcretation are due largely to increased lipid content and decreased chemical elimination efficiency of organisms occupying increasing trophic levels. The acculation of pollutant is expressed as the bioconcretation factor (BCF), wich is determined as the rate of its uptake to the organism and its elimination from it plus the organism growth rate. Chemical uptake efficiency from water, excretion rate, and chemical assimilation efficiency are variable as a function of the octanol-water partition coefficient (Kow).

In the wild fish there could be found a large range of parasites, but usually only present in small numbers. In contrast with cultured fish, outbreaks of parasitism in the wild may go unnoticed. The aim of this study was to describe and identify the acantocephalan endoparasite discovered in the intestine of free-living brown trout. Parasites recovered from the intestines of the infested brown trout living in Krka river were fixed in 10% neutral buffered formaline and identified regarding their body structures and features of the proboscis. Parasites were found mostly in the lower intestine of fishes. Well developed, strong based proboscis lined by 16-18 hooks in every row along with other body characteristics typical for males and females, indicated towards Pseudorhadinorhynchus salmothymi. This is the first report of P. salmothymi in brown trout of Krka river, the parasite that may severely damage fish intestine and threaten the life of the host.

Investigations of the adaptability of two growth groups of coho salmon fry (1+ and 0+) while being transferred from freshwater (FW) into seawater (SW) were performed in the season autumn/winter on four locations (three locations in the Adriatic Sea and one in the FW fish farm, Luknja). Average weight of the 1+ group was 116 g, and average weight of the 0+ group was 86 g. Changes in body composition and condition factor were examined immediately prior to SW transfer, during the early stages of smoltification and for a period of 30 days post-SW transfer. Fish samples (n=10/time point) were taken in FW, during the transport, and after the transfer into the sea (22.5, 45 and 90 min ; 3, 6 and 12 hours, and also 1, 2, 4, 8 and 30 days following the transfer). Results from the experiments demonstrate some differences in the adaptive fitness between the two age groups examined, with inferior adaptation being expressed by the 0+ group. Over the period of investigation an increase in body moisture and decreases in body lipid and protein were observed, when compared against FW controls regardless of smolt age. This might be interpreted as indicating malnourishment due to aphagia, since appetite loss has been described in this, and other oncorhynchids during SW transfer.

PCR je akronim za "polymerase chain reaction" (metoda lančane reakcije polimeraza), tehniku koja se temelji na otkrivanju i umnožavanju specifičnih DNA odnosno RNA sljedova. Može se primijeniti u dijagnostici naslijednih bolesti, forenzici, populacijskoj genetici, sistematici, bioinženjerstvu, evolucijskoj biologiji, pa i u akvakulturi. Ovom je metodom moguće dijagnosticirati niz virusnih, bakterijskih i parazitarnih bolesti riba, rakova i školjaka. Prednosti tehnike očituju se u brzom dobivanju rezultata, visokoj specifičnosti i osjetljivosti.

U Hrvatskoj postoji duga tradicija uzgoja školjaka, uz perspektivu daljnjeg razvoja školjkarstva. Kako su školjke osjetljivi organizmi koji zahtijevaju posebne uvjete uzgoja i klime, podložne su i mnogim bolestima. Bonamiozu, haplosporidiozu, marteiliozu, mikrocitozu i perkinsozu navodi Međunarodni ured za epizootije kao bolesti školjaka koje se prijavljuju po zakonu, a iridovirozu kao bolest od potencijalnog međunarodnog značaja. Iste bolesti su regulirane Zakonom o veterinarstvu iz 1997. godine., kao zarazne bolesti školjaka čije je spriječavanje i suzbijanje od interesa za Republiku Hrvatsku. Iako se ne suzbija po zakonu, u tekstu ovog članka je, zbog njene važnosti, opisana i Mytilicola bolest. Prema Pravilniku Ministarstva zdravstva iz 1994. godine, jestivi dio školjaka pretražuje se na toksine nekih morskih dinoflagelata, koji mogu biti štetni po ljudsko zdravlje, a to su PSP (Paralytic Shellfish Poison), DSP (Diarrhoeic Shellfish Poison) i NSP (Neuroparalytic Shellfish Poison).

Radi što boljeg uvida u zdravstveno stanje riba u jezeru Vrana na otoku Cresu, tijekom svih godišnjih doba mjerene su vrijednosti hematokrita, ukupnih proteina plazme i indeksa loma plazme ulovljenih riba. Istraživanja su provedena na sve četiri vrste riba koje žive u jezeru, a to su: drlja (Scardinius erythrophtalmus hesperidicus Heckel, 1838.), linjak (Tinca tinca Linnaeus, 1758.), bijeli klen (Leuciscus cephalus albus Bonaparte, 1838.), i štuka (Esox lucius Linnaeus, 1758). Krv je uzimana iz repne vene u mikrohematokritske kapilare. Ovisno o vrsti riba, hematokrit može znatno varirati. Vrijednosti hematokrita za ispitivane drlje, klenove i linjake su u veljači bile 29 plus/minus 5, 61, u svibnju 29, 53 plus/minus 7, 28, a štuke (jedna riba) 26 posto. U lipnju je hematokrit drlja, klenova i linjaka bio 26, 8 plus/minus 6, 32, štuke (jedna riba) 20 posto, dok je u kolovozu hematokrit drlja, klenova i linjaka bio 26, 8 plus/minus 4, 35. Hematokrit je kod linjaka bio izrazito viši zimi nego ljeti. U svim sezonama su mužjaci sve četiri vrste imali više vrijednosti hematokrita od ženki. Vrijednosti indeksa loma plazme su tijekom cijelog istraživanja bile ujednačene za sve pregledane vrste riba. Pojedinačni nalazi nekih vrijednosti proteina plazme ustanovljeni su u svibnju (linjak 1, 2 g/100 ml) i lipnju (linjak 1, 1 g/100 ml). Takva riba ima smanjenu količinu imunoglobulina, pa je podložna nizu bolesti. Prema literaturnim podacima (Goede i Barton, 1990) koeficijent varijabilnosti (KV) hematokrita veći od 15 posto može ukazivati na pojavu bolesti u dijelu riblje populacie. Budući da je kod većine pregledavanih riba u jezeru Vrana KV hematokrita bio veći od 15 posto, a bakteriološkim su analizama iz riba s nižim razinama hematokrita izdvojene i identificirane bakterije (iz rodova Aeromonas, Flavobacterium, Corynebacterium i Mycobacterium), može se zaključiti da su ribe u jezeru Vrana na granici biološke ravnoteže. Potencijalni stresori (kemijsko, organsko zagađenje) mogli bi narušiti ekološku ravnotežu, što će se najprije zamijetiti na zdravlju riba. Stoga treba voditi računa o svim promjenama u ekosustavu jezera Vrana.

Cestodoze su nametničke bolesti riba koje imaju posebno značenje u intenzivnoj ribarskoj proizvodnji, gdje kod riba razne starosti mogu izazvati promjene koje se nepovoljno odražavaju na uzgojne rezultate. Naš je cilj bio da na osnovu rezultata istraživanja provedenih na jednom šaranskom ribnjačarstvu u R. Hrvatskoj, dobijemo uvid u epizootiološko stanje manjeg akvatorija u kojem se odvija akvakulturna proizvodnja. Ujedno smo željeli utvrditi, postoji li povezanost izneđu kakvoće vode i pojave trakavičavosti šarana. Zbog toga smo istovremeno tijekom ulova riba za pretragu, uzimali i uzorke vode za fizikalno-kemijsku analizu kojom su obrađeni ovi kemijski parametri: T oC, pH, slob. koncentracija kisika, slob. CO2, permanganatni broj (KMnO4), NH4, NH3 i alkalitet (CaCO3, CaHCO3). Jednogodišnjim istraživanjem bila su obuhvaćena 392 šarana raznih starosnih skupina od čega ih je sa nametnicima iz skupine Cestoidea bilo invadirano 127 ili 32, 4%. Standardnom parazitološkom pretragom probavnog trakta šaranskog mlađa Šo+, jednogodišnjih šarana Š1+ i dvogodišnjih šarana Š2+ utvrđene su tri vrste trakavica. Utvrđeni broj (%) invadiranih šarana sa trakavicama u odnosu na broj parazitološki obrađenih šarana prema starosnim skupinama bio je slijedeći: Botriocephalus acheilognathi smo utvrdili kod 34 (8, 7%) Šo+ ; 28 (7, 1%) Š1+ i 10 (2, 6%) Š2+. Caryophillaeus fimbriceps kod 14 (3, 6%) Šo+, 25 (6, 4%) Š1+ i 3 (0, 77%) Š2+, a Khawia sinensis je utvrđena kod 4 (1, 02%) Šo+, 9 (2, 3%) Š1+, dok kod dvogodišnjih šarana nije utvrđena invadiranost s nametnicima ove vrste. Veći broj šarana svih starosnih skupina bio je invadiran trakavicama u mjesecu travnju i svibnju dok je invadiranost u ostalim mjesecima bila zanemariva zbog preporučene terapije. Liječenje je provedeno davanjem šaranima ljekovite hrane koja je sadržavala antiparazitik mebendazol. Rezultati istraživanja koja smo proveli bila su prema dostupnim literaturnim podacima istovjetni sa rezultatima takvih istraživanja provedenih u mnogim drugim zemljama svijeta.

Svrha istraživanja bila je pratiti razinu enzima transaminaza (aspartate aminotransferazu, AST i alanin transferazu, ALT) dviju genetskih skupina srebrnih lososa (diploidi i triploidi), te utvrđivanje ralike razine/aktivnosti enzima koje nastaju uslijed promjene kakvoće vode (slatka, morska voda). U provednim istraživanjima pratili smo fizikalno-kemijsku kakvoću slatke vode na ribogojilištu u Luknji, morske vode na kaveznom uzgajalištu Žrnovnica, te slatke i morske vode u akvarijskom prostoru u West Vancouver Laboratoriju, Vancouver, Kanada. Uzorci ribe (n=5-7) za određivanje biokemijskih parametara krvi uzimani su u slatkoj vodi, te nakon - 1, 5, -3, -6, -12 sati, te -1, -2, -4 i -8 dana po prebacivanju u morsku vodu. Uzimala se riba za biometrijska mjerenja, određivanje njenog zdravstvenog stanja, te krv za određivanje razine AST i ALT. Uzorci su obrađivani uz pomoć biokemijskog analizatora CHEM I. Rezultati istraživanja ukazali su na razlike aktivnosti enzima između diploidnih i jedne triploidne skupine lososa kod prebacivanja iz slatke u morsku vodu. Naime kod praćenja enzima AST vidljiv je trend pada vrijednosti u obje diploidne skupine, dok se kod triploidne skupine ne zapaža značajnija promjena. Praćenjem trenda kretanja enzima ALT, prilikom prebacivanja u morsku vodu vidljiv je trend rasta vrijednosti kod triploidne skupine i diploidne skupine iz pokusa u Hrvatskoj. Trend kretanja vrijednosti ovog enzima kod diploidne skupine držane u akvarijskom prostoru pokazuje pad vrijednosti. Iz dobivenih rezultata možemo zaključiti da je prilikom prilagođavanja srebrnih lososa životu u moru došlo do smanjene permeabilnosti staničnih membrana (pad razine AST), povećanja sinteze aminokiselina, što na koncu rezultira boljim rastom riba (rast razine ALT). Neosporna je dakle činjenica koja proizlazi iz izloženih rezultata da je došlo do promjena u aktivnosti istraživanih enzima prilikom promjene kakvoće vode. S obzirom da se zdravstvenim pregledom nije moglo utvrditi nikakvo oštećenje organa, a uginuća su bila minimalna, možemo jedino zaključiti da se radilo o kratkotrajnim funkcionalnim promjenama.

Jezero Vrana na otoku Cresu najveća je kriptodepresija u Hrvatskoj, stalno je jezero u karbonatnim stijenama i najbogatije jezero kvalitetnom pitkom vodom u kršu Hrvatske. Voda jezera je jedini izvor pitke vode na otocima Cres i Lošinj. U jezeru živi četiri vrste riba. Istraživanjima se nastojao dobiti uvid u zdravstveno stanje izlovljenih riba, a posredno steći spoznaje o stanju u sveukupnom ekosistemu te vodene sredine. Kroz sva godišnja doba ribe su lovljene i potom podvrgnute zdravstvenom pregledu. Uzimana im je krv za analizu, a iz unutrašnjih organa su nacijepljivani materijali za bakteriološku pretragu. Izdvojene bakterije identificirane su na temelju istraživanja njihovih morgoloških, uzgojnih i biokemijskih osobina. Pretraživana je osjetljivost tih bakterijskih sojeva prema antimikrobnim lijekovima. Uzimani su uzorci vode za fizikalno-kemijsku analizu. Patološkoanatomske promjene kod pregledavnih riba nisu bile brojne, zdravstveno i kondiciono stanje riba je bilo zadovoljavajuće. Prosječne vrijednosti serumskih proteina, specifične težine seruma i indeksa loma su kroz sve periode istraživanja i za sve veste riba bile ujednačene. Prosječna hematokritska vrijednost je bila povećana u veljači. Izdvojena su 54 bakterijska soja, svojim karakteristikama najsličnija Aeromonas sp. A. media, A. veronii, Flavobacterium sp., F. aquatile, Mycobacterium sp., Nocardia sp., Pasteurella piscicida, Pseudomonas sp., Enterobacter agglomerans, Edwardsiella ictaluri, Neisseria sp., Yersinia sp., Corynebacterium sp., uključivši 8 neidentificiranih gram-negativnih bakterija. Većina bakterija je bila vrlo ili umjreno osjetljivana testirana antimikrobna sredstva. Fizikalno-kemijske osobine jezerske vode su bile povoljne za život i razvoj vodenog svijeta. U okolnostima nepovoljnim za ribu, moglo bi doći do intenzivnijeg razmnažanja bakterija koje se na/u ribi nalaze. Stoga treba dovesti na minimum akutni i kronični stres u jezeru.

Cilj istraživanja bio je dobiti uvid u zdravstveno stanje pregledavanih linjaka i determinirati iz njih izdvojene bakterije. Istraživanja su nastavljena na prethodna (1989. i 1990. godine), kada su iz pregledavanih riba iz izdvojene samo ubikvitarne vodene bakterije. Zdravstvenom pretragom linjaka i bakteriološkom obradom izdvojenih izolata dobili smo podatke koji upućuju na dobar zdravstveni status riba u jezeru, te na postojanje ubikvitarnih i specifičnih ribljih bakterija kao potencijalnih uzročnika bolesti riba. Najveći broj izolata pripada skupini Aeromonas hydrophila, zatim Flavobacterium sp., Acinetobacter sp., Lactobacillus sp., te Aeromonas salmonicida. Te bakterije bi, u slučaju izraženog stresa riba i neravnoteže čimbenika koji uvjetuju život u vodi, mogle dovesti do pojave bolesti.

Istraživanja prilagodbe dviju starosnih grupa mlađi srebrnih lososa (1+ i 0+), pri prebacivanju iz slatke u morsku vodu, bila su provedena u sezoni jesen/zima na 4 lokaliteta u Jadranskom moru. Prosječna težina 1+ grupe bila je 116 grama, odnosno 0+ grupe 86 grama. Uzorci ribe (n=10) za određivanje kemijskog sastava mesa i faktor kondicije uzimani su u slatkoj vodi, tijekom transporta, te nakon 22, 5, 45 i 90 min., zatim 3, 6, 12 sati i poslije 1, 2, 4, 8, i 30 dana nakon prebacivanja u more. Za određivanje kemijskog sastava korištena je cijela riba (carcass composition). Određivana je količina bjelančevina, masti, pepela i vode. Rezulati istraživanja pokazuju razliku u prilagodbi između starosnih grupa (1+ i 0+). Vrijednosti masti su u obje skupine (1+ i 0+) na početku istraživanja više (7, 00+-1, 002 ; 7, 95+-2, 10) nego na kraju istaživanja (6, 16+-1, 74 ; 5, 11+-2, 26). Količina vlage pratila je obrnuto proporcionalno količinu masti u tkivu. Naime, na početku istraživanja je količina vlage u obje skupine ((1+ ; 0+) bila je niža (72, 59+-1, 78 ; 71, 73+-2, 02) nego na krju istaživanja (73, 60+-1, 97 ; 75, 32+-1, 98). Vrijednosti pepela se nakon 30 dana boracka ribe u moru neznatno razlikuju od onih u slatkoj vodi, dok se vrijednosti proteina istovremeno nešto smanjuju u obje skupine. Nakon 30 dana istraživanja došlo je do prilagodbe obiju starosnih skupina što je vidljivo iz rezultata.

Istraživanja su nastavljena na bakteriološke pretrage provedene tijekom 1989. i 1990. godine. Za ovo istraživanje primjerci riba lovljeni su u studenom 1995., veljači, svibnju i lipnju 1996. godine. Po obavljenom zdravstvenom pregledu, materijal za bakteriološku pretragu je uziman iz bubrega, slezene i jetre. Materijal je nasađen na TSA (Triptic soy agar) podloge. Preliminarna identifikacija bakterija je rađena diferencijalnim bojanjem po Gramu i određivanjem pokretljivosti. Provedena je pretraga biokemijskih svojstava bakterija, te njihove osjetljivosti na antimikrobna sredstva. Za razliku od prethodnih istraživanja, kada su gotovo svi izdvojeni izolati pripadali skupini Aeromonas hydrophila, prirodnom stanovniku slatkovodnih riba, nove pretrage pokazuju nalaze i drugih bakterija: A. salmonicida je jedan od najznačajnijih ribljih patogena. Pseudomonas anguiliseptica je potencijalni uzročnik patogenih stanja mnogih ribljih vrsta. Pasteurella piscicida može uzrokovati pomore kako uzgajane, tako i slobodne ribe. Izdvojeni su izolati morfološki sličnih Acinetobacter sp. i Neisseria, kojima još nisu poznati mehanizmi patogenosti. Izoliran je i veći broj Gram negativnih štapićastih bakterija: Flavobacterium sp., F. aquatile, F. "branchiophila", Flexibacter columnaris, Cytophaga aquatilis, koji se smatraju normalnom mikroflorom škrga zdravih riba i prirodna su pojava u vodenoj sredini, no uz određene uvjete mogu uzrokovati velike gubitke kod ribljih populacija. Od Gram pozitivnih štapića izdvojeni su Lactobacillus spp., Nocardia spp. i Mycobacterium fortiutum.

Despite the technological progress applied in recent years to the various production phases of Mediterranean Marine Fish Farming (MMFF), from reproduction to nutrition, several welfare and health issues of farmed fish still represent relevant limiting factors for sustainable production. In particular, the attempts to increase and diversify MMFF productions have been often accompanied by the emergence or reoccurrence of transmissible diseases strongly conditioned by management and environmental factors with consequent significant economic losses and repercussions on fish welfare and health parameters. The experience gained in the attempt to control diseases has amply demonstrated that the treatment (when applicable) is often not conclusive, highlighting that the “disease event” is the result of many interacting factors linked to the pathogen, the host and the environment (intended as production system and surrounding ecosystem), which underly the occurrence of disease and influence morbidity and mortality rates. It is evident that an integrated approach is required to prevent and control diseases of farmed fish, which means adopting a holistic view to take into consideration the integrated manner all the different factors involved in the development of a disease and in fish health management. Based on this concept, the project PerformFISH has developed in WP3 an integrated network of research activities aiming to provide the Mediterranean finfish aquaculture with effective tools to prevent, mitigate and control the most relevant diseases of European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata).

Despite the technological progress applied in recent years to the various production phases of Mediterranean Marine Fish Farming (MMFF), from reproduction to nutrition, several welfare and health issues of farmed fish still represent relevant limiting factors for sustainable production. In particular, the attempts to increase and diversify MMFF productions have been often accompanied by the emergence or reoccurrence of transmissible diseases strongly conditioned by management and environmental factors with consequent significant economic losses and repercussions on fish welfare and health parameters. The experience gained in the attempt to control diseases has amply demonstrated that the treatment (when applicable) is often not conclusive, highlighting that the “disease event” is the result of many interacting factors linked to the pathogen, the host and the environment (intended as production system and surrounding ecosystem), which underly the occurrence of disease and influence morbidity and mortality rates. It is evident that an integrated approach is required to prevent and control diseases of farmed fish, which means adopting a holistic view to take into consideration the integrated manner all the different factors involved in the development of a disease and in fish health management. Based on this concept, the project PerformFISH has developed in WP3 an integrated network of research activities aiming to provide the Mediterranean finfish aquaculture with effective tools to prevent, mitigate and control the most relevant diseases of European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata).

Virtually no comprehensive work has been published on tuna plasma chemistry parameters and its correlation with tissue histological status. This work will be useful for establishing plasma biochemistry reference values for bluefin tuna. Heparinized blood samples were collected from bluefin tuna. Plasma biochemical analyses were performed using standard techniques. Organ tissues were processed histologically and stained with haematoxylin/eosin. Mean, median, standard deviation, standard error of mean, 25th percentile, 75th percentile and range difference of minimum and maximum values were calculated for each variable measured. Obtained values represent preliminary results. All blood biochemistry parameters, except ALT, passed a Kolmogorov-Smirnov normality test. In a number of hepatocytes, different degrees of fatty changes were visible. Normal ranges of plasma activity vary between species and normal values must be produced from a representative population of each species. This work will be followed up by other studies on blood chemistry values of bluefin in the Adriatic Sea involving more individuals from several locations that could provide a base for reference levels

Analiza pročišćenih otpadnih voda koje se ispuštaju u vodene prijemnike uglavnom podrazumijeva tek utvrĎivanje koncentracije organskih tvari (kemijske i biološke potrošnje kisika) i nutrijenata (dušika i fosfora). Stoga je u ovom radu ispitan i učinak efluenta na bioindikatorske organizme (ribe (Carassius gibelio)) i gujavice (Eisenia fetida, Oligochaeta)) i stupanj rezistentnosti bakterijskih izolata na antimikrobne lijekove podrijetlom iz otpadnih voda, s ciljem utvrĎivanja štetnog djelovanja na ţiva bića u vodi, a posredno i na zdravlje ljudi. U tom smislu provedena su ekotoksikološka ispitivanja na bioindikatorskim modelnim organizmima, izvršeno je mjerenje mehanizma multiksenobiotičke otpornosti i vrijednosti parametara oksidacijskog stresa. Citogenetska oštećenja utvrđivana su mikronukleus testom a mutageni učinci Ames testom. Izvršena je komparativna mikrobiološka analiza standardnim mikrobiološkim testovima i MALDI-TOF spektrometrom masa, te su provedena hematološka i histopatološka istraţivanja. Rezultati navedenih istraţivanja pokazuju da pročišćene otpadne vode unošenjem ksenobiotika mijenjaju okolišne parametre recipijenta, dovode do porasta otpornosti bakterija na antibiotike, histopatoloških promjena i oksidacijskog stresa u riba. Dobiven je cjeloviti prikaz utjecaja pročišćenih otpadnih voda na ključne prarametre kakvoće i ekološkog stanja vode i biote. Currently, analysis of treated wastewater discharged from the wastewater treatment plants (WWTP) inflowing into recipients involves determination of concentrations of organic substances (chemical and biological oxygen demand) and nutrients (nitrogen and phosphorus). In this study, the impact of effluent on organismic bioindicators and degree of resistance of bacterial isolates to antimicrobial drugs originating from wastewater has been evaluated with the aim to determine toxic effects on aquatic (fish, Carassius gibelio) and terrestrial (earthworm, Eisenia fetida, Oligochaeta) organisms, and indirectly on human health. The ecotoxicological testings on bioindicator model organisms were conducted, measuring mechanisms of multixenobiotic resistance and parameters of oxidative stress. Cytogenetic damages were determined by micronucleus test, and mutagenic effects with Ames test. Comparative microbiological analyses were made with conventional methods and mass spectrometry analyser. Results of this study show that treated wastewater (leaving WWTP) changed environmental parameters by introduction of xenobiotics, contributed to microbial contamination and antimicrobial resistance, histopathological tissue changes and oxidative stress of examined organisms. Hencewith, our approach encompassed an integrated overview of the impact of treated wastewater on key environmental and organismal parameters.