Marine Water Samples Research Articles

Glyphosate and AMPA in the estuaries of the Baltic Sea method optimization and field study

Water samples from ten German Baltic estuaries were collected in 2012 in order to study the presence of the herbicide glyphosate, its primary metabolite AMPA and their potential transport to the marine environment. For the analyses an LC–MS/MS based analytical method after derivatization with FMOC-Cl was optimized and validated for marine water samples. All investigated estuarine stations were contaminated with AMPA and nine of them also with glyphosate. Concentration ranges observed were 28 to 1690ng/L and 45 to 4156ng/L for glyphosate and AMPA, respectively with strong spatial and temporal fluctuations. Both contaminants were found at inbound sampling sites in the stream Muehlenfliess and concentrations decreased along the salinity gradient to the estuaries of the Baltic Sea. The data obtained in this study clearly depict the transport of glyphosate and AMPA to the Baltic Sea. Hence, detailed fate and risk assessment for both contaminants in marine environments are required.

Antimicrobial resistance of Pseudomonas spp. isolated from wastewater and wastewater-impacted marine coastal zone.

In this study, species distribution and antimicrobial susceptibility of cultivated Pseudomonas spp. were studied in influent (INF), effluent (EFF), and marine outfall (MOut) of wastewater treatment plant (WWTP). The susceptibility was tested against 8 antimicrobial classes, active against Pseudomonas spp.: aminoglycosides, carbapenems, broad-spectrum cephalosporins from the 3rd and 4th generation, extended-spectrum penicillins, as well as their combination with the β-lactamase inhibitors, monobactams, fluoroquinolones, and polymyxins. Among identified species, resistance to all antimicrobials but colistin was shown by Pseudomonas putida, the predominant species in all sampling points. In other species, resistance was observed mainly against ceftazidime, ticarcillin, ticarcillin-clavulanate, and aztreonam, although some isolates of Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas pseudoalcaligenes, and Pseudomonas protegens showed multidrug-resistance (MDR) phenotype. Among P. putida, resistance to β-lactams and to fluoroquinolones as well as multidrug resistance become more prevalent after wastewater treatment, but the resistance rate decreased in marine water samples. Obtained data, however, suggests that Pseudomonas spp. are equipped or are able to acquire a wide range of antibiotic resistance mechanisms, and thus should be monitored as possible source of resistance genes.

Determination of Ammonia, Nitrate and Nitrite Concentrations in Marine Water Samples with Cultured Marine Ornamental Fish Water Sample Analysis

The present studies were concentration of ammonia, nitrite, nitrate, dissolved oxygen, temperature, salinity and pH. For seven physicochemical parameters were determined in marine water samples along with marine ornamental fish water sources from CAS in marine biology laboratory conditions at Parangipettai. Water sample have been studied at a marine water sources. The study concentrations of parameters like ammonia, nitrite, nitrate, dissolved oxygen, temperature, salinity, and pH. And physicochemical parameters have been calculated. The data showed the difference of the investigated parameters in samples as follows; Concentration of water quality parameters like ammonia was maximum level above 1.158 μmol¯1, nitrite was ranging from 0.811 to 0.922 μmol¯1, nitrate was range maximum level above 4.84 μmol¯1, dissolved oxygen content was maximum level above 2.4 mg¯1, temperature was ranging from 32.3 to 100 °C, salinity values ranging from 0 to 36ppt and pH was ranging from 6.5 to 8.0. During the study period of from July 2013 to June 2014 we investigated concentration of seven physicochemical parameters value Marine water samples with cultured fish species in presence of water from CAS in Marine Biology laboratory Annamalai University at Parangipettai.

Determination of Ammonia, Nitrate and Nitrite Concentrations in Marine Water Samples with Cultured Marine Ornamental Fish Water Sample Analysis

The present studies were concentration of ammonia, nitrite, nitrate, dissolved oxygen, temperature, salinity and pH. For seven physicochemical parameters were determined in marine water samples along with marine ornamental fish water sources from CAS in marine biology laboratory conditions at Parangipettai. Water sample have been studied at a marine water sources. The study concentrations of parameters like ammonia, nitrite, nitrate, dissolved oxygen, temperature, salinity, and pH. And physicochemical parameters have been calculated. The data showed the difference of the investigated parameters in samples as follows; Concentration of water quality parameters like ammonia was maximum level above 1.158 μmol¯1, nitrite was ranging from 0.811 to 0.922 μmol¯1, nitrate was range maximum level above 4.84 μmol¯1, dissolved oxygen content was maximum level above 2.4 mg¯1, temperature was ranging from 32.3 to 100 °C, salinity values ranging from 0 to 36ppt and pH was ranging from 6.5 to 8.0. During the study period of from July 2013 to June 2014 we investigated concentration of seven physicochemical parameters value Marine water samples with cultured fish species in presence of water from CAS in Marine Biology laboratory Annamalai University at Parangipettai.

Laboratory calibration and field testing of the Chemcatcher-Metal for trace levels of rare earth elements in estuarine waters.

Little knowledge is available about water concentrations of rare earth elements (REEs) in the marine environment. The direct measurement of REEs in coastal waters is a challenging task due to their ultra-low concentrations as well as the high salt content in the water samples. To quantify these elements at environmental concentrations (pg L(-1) to low ng L(-1)) in coastal waters, current analytical techniques are generally expensive and time consuming, and require complex chemical preconcentration procedures. Therefore, an integrative passive sampler was tested as a more economic alternative sampling approach for REE analysis. We used a Chemcatcher-Metal passive sampler consisting of a 3M Empore Chelating Disk as the receiving phase, as well as a cellulose acetate membrane as the diffusion-limiting layer. The effect of water turbulence and temperature on the uptake rates of REEs was analyzed during 14-day calibration experiments by a flow-through exposure tank system. The sampling rates were in the range of 0.42 mL h(-1) (13 °C; 0.25 m s(-1)) to 4.01 mL h(-1) (13 °C; 1 m s(-1)). Similar results were obtained for the different REEs under investigation. The water turbulence was the most important influence on uptake. The uptake rates were appropriate to ascertain time-weighted average concentrations of REEs during a field experiment in the Elbe Estuary near Cuxhaven Harbor (exposure time 4 weeks). REE concentrations were determined to be in the range 0.2 to 13.8 ng L(-1), where the highest concentrations were found for neodymium and samarium. In comparison, most of the spot samples measured along the Chemcatcher samples had REE concentrations below the limit of detection, in particular due to necessary dilution to minimize the analytical problems that arise with the high salt content in marine water samples. This study was among the first efforts to measure REE levels in the field using a passive sampling approach. Our results suggest that passive samplers could be an effective tool to monitor ultra-trace concentrations of REEs in coastal waters with high salt content.

Flow cytometric applicability to evaluate UV inactivation of phytoplankton in marine water samples

Disinfection of microbes is of importance to prevent the spread of pathogens and non-indigenous species in the environment. Here we test the applicability of using flow cytometry (FCM) to evaluate inactivation of the phytoplankter Tetraselmis suecica after UV irradiation and labeling with the esterase substrate 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM). Non-irradiated and UV irradiated samples were analyzed with the plate count technique and FCM for 24days. The numbers of colony forming units were used as a standard to develop a FCM protocol. Our protocol readily distinguishes live and dead cells, but challenges were encountered when determining whether UV damaged cells are dying or repairable. As damaged cells can represent a risk to aquatic organisms and/or humans, this was taken into account when developing the FCM protocol. In spite of the above mentioned challenges we argue that FCM represents an accurate and rapid method to analyze T. suecica samples.

Promising Biological Indicator of Heavy Metal Pollution: Bioluminescent Bacterial Strains Isolated and Characterized from Marine Niches of Goa, India.

In present study, several marine water samples collected from the North Goa Beaches, India for isolation of luminescent bacterial species. Isolates obtained labelled as DP1-5 and AB1-6. Molecular characterization including identification of a microbial culture using 16S rRNA gene based molecular technique and phylogenetic analysis confirmed that DP3 & AB1 isolates were Vibrio harveyi. All of the isolates demonstrated multiple metal resistances in terms of growth, with altered luminescence with variable metal concentration. Present investigations were an attempt towards exploring and reporting an updated diversity of bioluminescent bacterial species from various sites around the Goa, India which would be explored in future for constructing luminescence based biosensor for efficiently monitoring the level of hazardous metals in the environment.

<i>In vitro</i> cytotoxic and antibacterial potentials of extracts from three marine isolates of Actinomycetes isolated from coastal ecosystems of Tanur, Kerala, India

Three Actinomyctes with potential bioactivity are successfully isolated from the marine water samples and identified as Prauserella marina , Streptomyces sindenensis and S. spiroverticillatus . The ethyl acetate extracts from the three Actinomycetes are found to have significant bioactivity. The highest anti-bacterial activity was given by the extract from P. marina on B. cereus showing 28 mm of zone of inhibition. Cytotoxicity screening of the crude extracts using 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) cell viability assay revealed that extract from P. marina noticeably effected the viability of the human cervical cancer cell grown in vitro . Thin layer chromatography of the crude extract with methanol and chloroform (8:2) as solvent system yielded three distinct fractions, of which fraction with Rf value 0.8 resulted in 77, 68, 54 and 40% growth inhibition of HeLa cells at 15, 10, 5, 2.5 µg/mL, respectively with the IC 50 value as 3.3 µg/mL. HPLC analysis of the fraction resulted in single major peak at 3.7 min.

Bioactive Metabolites from Indigenous Actinomycetes Isolated from Marine Water

Microbial natural products have continued to play an important role in the discovery of novel chemicals for the development of important therapeutic agents. Actinomycetes form a potent reservoir of biologically active secondary metabolites and enzymes. The need for finding novel bioactive compounds for the development of new therapeutic agents is required due to the emergence of antibiotic resistance among pathogenic bacteria. Actinomycetes are considered as one of the best producers of variety of antagonistic compounds that could serve as potential chemotherapeutic agents. The present study was undertaken to find new antagonistic compounds from actinomycetes. Actinomycetes were successfully isolated from marine water samples collected at various locations of Karachi. Initially 39 isolates were collected out of which 23 were found to produce active metabolites against one or more test bacterial cultures. Actinomycetes strains IS26, IS33, and IS39 showed significant potential of having bioactive metabolites. Further, the spectrum of those strains was tested against gram positive and gram negative bacteria and results showed variable potential of actinomycetes to inhibit bacterial growth.

Microbial diversity in Catba island. Part 1: the number and distribution

Catba one of the world biosphere reserves admitted by UNESCO in 2004 consists 367 islands located in Lanha bay and contains all biodiversity-reserved values. Despite the number of scientific reports focus on the diversity of Catba marine animals and plants, valuable researches on microbial communities, which play an essential role in nature element cycles and have many potential uses, is still lacking. Recently, we have carried out a survey to assess the microbial potential in Catba marine water. The analyzed data on microorganisms in Catba marine water and sediment showed that the distribution and the quantity of each individual microorganism were different according to the depth: the quantities of microorganisms in the sediment samples were higher than those in the marine water samples from 10-103 fold. The number of each microorganism was various: 105 - 3.4 ´ 107 aerobic, 104 - 107 fermentative, 104 - 5 ´ 105 hydrocarbon utilizing, 101 - 5 ´ 105 sulfate-reducing and 101 - 106 nitrogen conversion bacteria. Fungi and yeast are present in only few collected samples with low number. Classification of the dominant microorganisms based on their morphology, chemo taxonomy or 16S r RNA sequence analysis exhibited that they are belonging to the species: Acinetobacter johnsonii, Pseudomonas vesicularis, Pseudomonas aeruginosa, Pseudomonas cepacia, Flavobacterium indologenes, Sphingomonas paucimobilis, Ochrobactrum cytisis, Janibacter marinus, Bacillus megatherium, Cladosporium spherospermum, Penicillium oxalicum, Candida parasilosis and Rhodotorula musilaginosa, Streptomyces celluloflavus, Streptomyces sclerotialus. This preliminary result is important step towards applying the useful microorganisms for environmental pollution control and limiting the effect of harmful microorganisms.

Description of Pyramimonas diskoicola sp. nov. and the importance of the flagellate Pyramimonas (Prasinophyceae) in Greenland sea ice during the winter–spring transition

Pyramimonas Schmarda is a genus of unicellular green flagellates, recorded in marine water and sea ice samples. Pyramimonas is within the prey size range of the most important protozoan grazers in Disko Bay, West Greenland, where this study took place. Despite the potential ecological importance, little is known about the occurrence of the genus. The aim of this study was to explore the biomass of Pyramimonas in developing stages of sea ice and in the water column. Pyramimonas colonized the early stages of sea ice, and the highest percent of Pyramimonas biomass was found in grease ice. The biomass of Pyramimonas was more than a magnitude higher within sea ice compared to the surface water. The results illustrate that Pyramimonas from the ice is an important contributor to the plankton community prior to the spring bloom. An undescribed species, Pyramimonas diskoicola sp. nov., was found. Based on morphology and ultrastructure, combined with molecular phylogeny inferred from the small-subunit SSU rDNA and the large-subunit chloroplast-encoded rbcL, the species was placed in subgenus Vestigifera. The cells possessed four flagella, measured 8.3 ± 2.6 μm in length and 5.1 ± 0.8 μm in width, and were characterized by an uplifted quadrant in the center of the box scales, not seen at any other Pyramimonas species. The phylogenetic analyses indicated P. diskoicola to be closely related to other polar sea ice species of Pyramimonas.

Labrenzia sp. BM1: a quorum quenching bacterium that degrades N-acyl homoserine lactones via lactonase activity.

We report the degradation of quorum sensing N-acylhomoserine lactone molecules by a bacterium isolated from a Malaysian marine water sample. MALDI-TOF and phylogenetic analysis indicated this isolate BM1 clustered closely to Labrenzia sp. The quorum quenching activity of this isolate was confirmed by using a series of bioassays and rapid resolution liquid chromatography analysis. Labrenzia sp. degraded a wide range of N-acylhomoserine lactones namely N-(3-hexanoyl)-l-homoserine lactone (C6-HSL), N-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-C6-HSL) and N-(3-hydroxyhexanoyl)-l-homoserine lactone (3-hydroxy-C6-HSL). Re-lactonisation bioassays confirmed Labrenzia sp. BM1 degraded these signalling molecules efficiently via lactonase activity. To the best of our knowledge, this is the first documentation of a Labrenzia sp. capable of degrading N-acylhomoserine lactones and confirmation of its lactonase-based mechanism of action.

Aquatic model for engine oil degradation by rhamnolipid producing Nocardiopsis VITSISB.

The present study was focused on isolation, screening, characterization and application of biosurfactant producing marine actinobacteria. Twenty actinobacteria were isolated from marine water sample and were primarily screened for biosurfactant production using hemolytic activity method. Among the 20 isolates, six showed positive result for hemolytic activity and those were taken for further secondary screening tests such as oil collapse method, oil spreading method and emulsification method. From the results of secondary screening analysis, two isolates (SIS-3 and SIS-20) were selected and further used to carry out biosurfactant characterization test such as pH, density, surface tension and viscosity determination. Comparing biosurfactant characterization results, SIS-3 was chosen for further analysis and application. FT-IR and GC–MS were carried out for analysis of biosurfactant from isolate SIS-3 and the compound detected was rhamnolipid. The isolate (SIS-3) was identified as Nocardiopsis using 16S rRNA gene sequencing and named as ‘Nocardiopsis VITSISB’ (KC958579) which was further applied for immobilizing whole cells for engine oil degradation by constructing an aquatic model and using natural products such as soybean meal, sugarcane juice as nutrient source. The oil was efficiently degraded by rhamnolipid producing Nocardiopsis VITSISB (KC958579) within 25 days which indicated that the strain can act as a natural candidate for the bioremediation of oil spill in ocean.

Determination of nitrate plus nitrite in small volume marine water samples using vanadium(III)chloride as a reduction agent

In this contribution a method to analyse nitrate in marine pore water, seawater and freshwater is presented. The method serves to replace the well-known cadmium column method for the reduction of nitrate to nitrite. Instead, acidic vanadium(III)-solution is used for the reduction avoiding the toxic Cd metal. Both, the already present and the newly produced nitrite are quantified by the established Griess–Ilosvay reaction. Sample preparation is easy because only one reagent solution has to be added to the sample. Efficiency of the nitrate reduction is 100±3% (n=12) using either a reaction time of 60min at 45°C or 10–20h at room temperature. Measurements can either be done by conventional UV–VIS spectrophotometry using 1–5cm cuvettes, by discrete sequential analysers based on the loop flow technique, by continuous flow technique or, when only small sample volumes are available, by microtiter plate readers (MR) in absorbance mode. The latter method requires only 0.5mL of a sample for nitrite and nitrate quantification and has a precision of 2%. The limit of detection of the MR technique is comparable to conventional methods using a 1cm cuvette (0.4μM for nitrate, 0.07μM for nitrite). The method requires only a spectrophotometer, and is simple and cost-effective; sample preparation is rapid and a salt error or an interference by dissolved organic carbon is not evident. Interferences induced by naturally coloured samples, or hydrogen sulphide can be corrected or eliminated. A procedure for direct nitrate determination is given as well as a procedure to compensate for the small loss of nitrite by nitric oxide formation for the nitrite present prior to the addition of a reductant.

Highly Sensitive Liquid Chromatography-Mass Spectrometry Detection of Microcystins with Molecularly Imprinted Polymer Extraction from Complicated Aqueous Ecosystems

In the present study, a liquid chromatography-mass spectrometry (LC-MS) method has been developed and validated to monitor traces of microcystins (MCs) in lake and marine waters. The molecularly imprinted polymer (MIP) formulated with itaconic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinking monomer has been used to selectively enrich MCs from the aqueous solutions. The extraction capacity and selectivity of MIP was higher when comparison with conventionally used resin XAD and powdered activated carbon (PAC). The MIP showed an outstanding selectivity for microcystin-LR (MC-LR) in a mixture of MCs from aqueous solutions in the pH range 6-9. The LC-MS analysis of MCs after MIP extraction showed an excellent linearity in the working range (R2=0.998) with high repeatability (RSD%, <6.3) and recoveries above 90%. Interference of dissolved ions and solution pH on MCs trace quantification in the lake and marine water samples were quantified. The limits of quantification (LOQ) and lower limit of detection (LOD) for the MC-LR were 10 and 1 ng L-1, respectively, which satisfies the strictest World Health Organization standard for MC-LR in drinking water (1 ng mL-1). The proposed analytical approach is simple, efficient and comparable with the detection limit of the traditional and expensive ELISA method of MCs analysis.

Statistical approach for production of PUFA from Kocuria sp. BRI 35 isolated from marine water sample.

In this study, Plackett-Burman design was used to identify the most influential parameters affecting PUFA production by Kocuria sp. BRI 35 isolated from Antarctic water sample. Amongst 10 variables evaluated, magnesium chloride, protease peptone, glucose, and temperature were significant. Response surface methodology consisting of a central composite design was developed to study the interactions between the variables and to determine optimal values of significant variables. A quadratic model (R = 0.9652, F = 14.64, P < 0.0001) was built. The contour plots indicated that the isolate produced maximum PUFA at lower concentrations of magnesium sulfate (0.9 g/L) and higher concentrations of protease peptone (5 g/L) and glucose (10 g/L) at 15°C. MgSO4 and glucose exhibited quadratic as well as interactive effect on PUFA production whereas protease peptone and temperature showed interactive effects only. After optimization, PUFA production per unit biomass increased from 0.94 mg/g to 11.12 mg/g. This represented an increase from 3% to 58.62% of the total fatty acids. Among PUFAs, the yield of ω-6 fatty acids increased from 9.66 mg/L to 107.71 mg/L with significant increase in linoleic acid (20.36 mg/L) whereas ω-3 fatty acids increased up to 12.37 mg/L with DHA being the major ω-3 fatty acid produced.

Identification and biotechnological potential of psychrotrophic marine isolates

Background: Importance of microbial metabolites in food, detergent, pharmaceutical, nutraceutical and cosmetic industries has now been widely established. To fulfill the requirement of these industries, psychrophilic/psychrotrophic marine microbes are being explored. These microbes help in the production of metabolites that are active and stable at extreme physiological conditions. In correlation with this scenario, the present study reports identification of 14 bacterial isolates (BRI 32- BRI 45) from marine water samples (out of which 4 are Antarctic) with emphasis on their biotechnologically important characters. Material and Methods: Bacterial isolates were identified using 16S rRNA gene sequencing. Growth of the isolates under different physiological conditions of temperature (10°C to 45°C), pH (3-10) and concentration of NaCI (0-20%) was studied. Further, the isolates were examined for their ability to produce i) polyunsaturated fatty acids, ii) industrially important enzymes and their potential to produce bio-surfactant. Results: 16S rRNA gene sequence analysis revealed that the isolates belonged to Halomonas, Brevibacillus, Kocuria and Oceanobacillus genera. Our results indicated that the isolates could grow over a wide range of physiological conditions of pH (3-10), temperature (10-45°C) and NaCI concentration. Eight out of 14 isolates showed the presence of omega-3 and omega-6 fatty acids. BRI 34 was found to produce significant amounts of eicosapentaenoic acid (39.66%). Most of the isolates exhibited the ability to produce 3 or 4 enzymes. Only BRI 35 showed potential for biosurfactant production. Conclusions: Our findings suggest potential of these isolates for biotechnological applications.

Application of the experimental design of experiments (DoE) for the determination of organotin compounds in water samples using HS-SPME and GC–MS/MS

When attempting to discover the important factors and then optimise a response by tuning these factors, experimental design (design of experiments, DoE) gives a powerful suite of statistical methodology. DoE identify significant factors and then optimise a response with respect to them in method development. In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography tandem mass spectrometry (GC-MS/MS) methodology for the simultaneous determination of six important organotin compounds namely monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT) has been optimized using a statistical design of experiments (DOE). The analytical method is based on the ethylation with NaBEt4 and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC-MS/MS analysis. The main experimental parameters influencing the extraction efficiency selected for optimization were pre-incubation time, incubation temperature, agitator speed, extraction time, desorption temperature, buffer (pH, concentration and volume), headspace volume, sample salinity, preparation of standards, ultrasonic time and desorption time in the injector. The main factors (excitation voltage, excitation time, ion source temperature, isolation time and electron energy) affecting the GC-IT-MS/MS response were also optimized using the same statistical design of experiments. The proposed method presented good linearity (coefficient of determination R(2)>0.99) and repeatibilty (1-25%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked surface and marine waters was higher than 70% for all compounds studied. Finally, the optimized methodology was applied to real aqueous samples enabled the simultaneous determination of all compounds under study in surface and marine water samples obtained from Valencia region (Spain).

Bioactivity Assay of an Isolated Marine Fusarium sps

Marine fungi are the potential and promising sources for biologically active secondary metabolite productions. Secondary metabolites are the chemical compounds that are produced during the stationary phase of the organism. Many years of study revealed that fungi are excellent sources for novel bioactive secondary metabolites. In the present study fungi were isolated from marine water samples and serial dilution method was performed to isolate single colonies. Later microscopic and macroscopic observations were done to identify the organism. Organisms are inoculated into medium for production of secondary metabolites. One week later ethyl acetate is added to the broth in 1:1 ratio and kept for incubation in shaker. Solvent is separated by separating funnel and solvent is extracted by rotavapour to collect the crude extract. Crude extract is dissolved in DMSO and further tested for biological activities. The Fungi was identified as Fusarium species and its secondary metabolites showed potential antimicrobial activity. The present work was attempted to isolate organisms which are capable of producing efficient antibacterial and antifungal compounds. Further we identified the organism as Fusarium sp. The future scope of this work is to isolate these biologically active compounds to use in pharmaceutical applications.

Occurrence, characterization and antimicrobial susceptibility of Vibrio alginolyticus in the Eastern Adriatic Sea

In 2007–2008, 162 samples (72 marine water samples, 90 swabs from the gills and skin) were collected from three European seabass fish farms in Eastern Adriatic. The aim of study was to determine the occurrence of Vibrio, to identify the isolated strains and to investigate their antimicrobial resistance. The comparison of the results obtained in spring and autumn periods indicated a higher Vibrio concentration in spring samplings. The greatest prevalence of Vibrio alginolyticus was on gills than on skin, whereas statistically significant differences were obtained between sampling periods with maximal prevalence in spring. Vibrio isolates from the marine water and from swabs of European seabass were analysed by DNA sequencing of partial 16S rDNA and gyrB genes and identified as V. alginolyticus. Isolates were highly susceptible to flumequine, chloramphenicol and oxytetracycline.