The Influence of Aquaculture Effluents on the Prevalence and Biocides Resistance of Opportunistic Pseudomonas fluorescens Bacteria in the Drwęca River Protected under the Natura 2000 Network

The aim of this study was to determine the effect of trout aquaculture effluents on the Drwęca River. The count of opportunistic pathogen Pseudomonas fluorescens (OPPF) in the total Pseudomonas fluorescens population (TPFP) were determined by plating on King B medium and fluorescence in situ hybridization. The resistance of OPPF strains to 12 antibiotics and two disinfectants was evaluated. Significant differences (p ≤ 0.05) in OPPF counts were found between seven sampling sites. OPPF counts were highest in samples collected directly downstream from three fish farms. More than 50% of these isolates demonstrated multiple-drug resistance to ampicillin, mezlocillin, cefotaxime, norfloxacin, tetracycline and two disinfectants (Steridial and chloramine T). Of these, 52% were resistant to high doses of cefotaxime and norfloxacin (MIC ≥ 256 µg·mL−1), and 65% were resistant to the maximum doses of Steridial (MIC Ste ≥ 25 mL·m−3) and chloramine T (MIC Chlor ≥ 20 mg·L−1). All OPPF sampled upstream from the farms were sensitive to low concentrations of CTX (cefotaxime) and NOR (norfloxacin) (MIC ≤ 2 µg·mL−1), Steridial (MIC Ste ≤ 5 mL·m−3) and chloramine T (MIC Chlor ≤ 2.5 mg·L−1). Agglomerative clustering revealed two clusters: strains from samples collected upstream and downstream from trout farms. The results indicate that aquaculture effluents significantly affect the prevalence of biocides resistant OPPF along the river continuum

The Influence of Commercial Feed Supplemented with <i>Carnobacterium maltaromaticum</i> Environmental Probiotic Bacteria on the Rearing Parameters and Microbial Safety of Juvenile Rainbow Trout

The aim of this study was to determine the effect of commercial feed (CF) supplemented with 0.1% of the Carnobacterium maltaromaticum environmental probiotic strain on the rearing parameters, apparent nutrient digestibility, and microbial safety of juvenile rainbow trout (Oncorhynchus mykiss). The fish were fed CF (control group, CG) and experimental feed (EF) supplemented with 0.1% of C. maltaromaticum (experimental group, EG) for 56 days. The final body weight and total body length of the fish were measured. The growth rate, condition factor, feed conversion ratio, viscerosomatic and hepatosomatic indices, and apparent digestibility coefficients of protein (PAD), lipids (LAD), ash (AAD), and nitrogen-free extract (NFEAD) were calculated. The total viable counts of C. maltaromaticum bacteria, mesophilic bacteria, hemolytic mesophilic bacteria, Pseudomonas fluorescens, Aeromonas hydrophila, Staphylococcus sp., and sulfite-reducing anaerobic spore-forming Clostridium sp. were determined in digestive tract contents and the skin of fish. Feed supplementation with C. maltaromaticum significantly affected most rearing parameters, as well as the PAD, LAD, AAD and NFE values, and bacterial counts. The principal component analysis (PCA) revealed significant positive correlations (p C. maltaromaticum counts in the EF and in the digestive tract contents of the fish

Water as a Source of Indoor Air Contamination with Potentially Pathogenic Aeromonas hydrophila in Aquaculture

Human activities influence the presence of potentially pathogenic bacteria in indoor air. The aim of this study was to determine the effect of the experimental rearing of European grayling and European perch in a recirculating aquaculture system on the contamination of indoor air with potentially pathogenic Aeromonas hydrophila (PPAH) and the resulting health risks to humans. The PPAH counts, their resistance to seven antibiotics, and the multiple antibiotic resistance (MAR) index were determined in samples of indoor air and water from rearing tanks. The PPAH counts were highest in the laboratory bioaerosol where two fish species were reared. The calculated indoor/outdoor ratio (I/O &gt; 1) demonstrated that tank water was the internal source of PPAH emissions. The unconstrained PCA revealed strong positive relationships (p &le; 0.05) between the PPAH counts in the indoor air and water samples. Most of the PPAH strains isolated from laboratory air were resistant to tetracycline, cefotaxime, and erythromycin, and 26&ndash;82% of the isolates exhibited multiple drug resistance. The values of the MAR index were similar in samples of laboratory air and water (0.23&ndash;0.34 and 0.24&ndash;0.36, respectively). Agglomerative clustering revealed two clusters of strains isolated from laboratory air and tank water. The results of this study indicate that aquaculture can be a source of indoor air contamination with PPAH

Zooplankton communities in a river downstream from a lake restored with hypolimnetic withdrawal

Restoring lakes with hypolimnetic withdrawal can severely threaten water quality and biocenosis downstream. The objective of this study was to evaluate the effect of lake restoration on riverine zooplankton during a period of intense hypolimnion water inflow. Zooplankton density and biomass were determined in water samples. The water samples were also analyzed to determine the following physicochemical parameters: flow rate, dissolved oxygen, hydrogen sulphide, sulphate, ammonium nitrogen, nitrate nitrogen, total phosphorous, soluble reactive phosphorus, total organic carbon, and temperature. The results of multiple regression indicated that water flow was the most significant variable and was the best predictor of total zooplankton and rotifer density. Soluble reactive phosphorous was the main predictor of copepod biomass and density. Our study showed that hypolimnetic withdrawal disturbed the natural process of planktic community transformation, which was linked to the environmental shift from lacustrine to riverine. During the study, zooplankton density and biomass were low, but not as low as when the pipeline was operating at maximum output. At present, this lake restoration method has become more sustainable, because the adverse effects of hypolimnetic withdrawal on the recipient river have been minimized and limited to several weeks

Distribution of <i>Pseudomonas fluorescens</i> and <i>Aeromonas hydrophila</i> Bacteria in a Recirculating Aquaculture System during Farming of European Grayling (<i>Thymallus thymallus</i> L.) Broodstock

Pseudomonas fluorescens and Aeromonas hydrophila bacteria are opportunistic pathogens that occur naturally in the aquatic environment and in the gut flora of healthy fish. Both species can pose a serious threat for fish that are highly sensitive to water pollution. The aim of this study was to determine the extent to which the amount of administered fish feed and fish biomass affect the distribution and abundance of Ps. fluorescens and A. hydrophila bacteria in a recirculating aquaculture system (RAS) during farming of European grayling (Thymallus thymallus L.) broodstock. A total of 68 water samples from the inflow, two rearing tanks and the outflow as well as 17 feed samples were collected and analyzed separately. Bacterial populations were analyzed by the culture-dependent method and a molecular method (fluorescence in situ hybridization, FISH) to detect culturable strains and viable but non-culturable strains, respectively. Fish biomass, feed and 16 water quality parameters (temperature, pH, concentration of dissolved oxygen, oxygen saturation, five-day biochemical oxygen demand (BOD5), total phosphorus, total organic phosphorus and nitrogen, orthophosphates, total nitrogen, nitrite and nitrate nitrogen, ammonia nitrogen, ammonium nitrogen, total suspended solids, and total organic carbon) were the explanatory factors. Statistically significant differences (RM-ANOVA, p &#8804; 0.05) were stated in bacterial abundance in samples from the inflow, rearing tanks and the outflow. Water samples from the RAS were abundantly colonized by non-culturable Ps. fluorescens and A. hydrophila bacteria. Feed was not a source of bacteria, but a redundancy analysis (RDA) revealed that the amount of feed, fish biomass, BOD5, and total suspended solids and total organic carbon were positively correlated in both Ps. fluorescens and A. hydrophila. These parameters also influenced the distribution of both potentially pathogenic bacterial populations and contributed to the bacterial contamination of water in the RAS. Our results are particularly valuable for aquacultures that help to replenish wild stocks and rebuild populations of threatened species in natural aquatic environments

The effect of lake restoration by the hypolimnetic withdrawal method on the intensity of ambient odour

The objective of this study was to evaluate the effect of lake restoration by the hypolimnetic withdrawal method on the intensity of ambient odour in the vicinity of the pipeline outlet. The study was carried out in 2012-2013 from the beginning of the summer stagnation period in Lake Kortowskie to complete overturn in fall. Samples of river water and ambient air were collected from two sites: near the pipeline outlet (PO) and behind the academic campus (AC). A total of 44 air samples and 44 water samples were analysed. Odour intensity was measured in samples of ambient air. The following physicochemical parameters of water were determined: flow rate, dissolved oxygen (DO), hydrogen sulphide (H2S), sulphate (SO4), ammonium nitrogen (NH4-N), total nitrogen (TN), dissolved nitrogen (DN), total particulate nitrogen (T-PN), total organic carbon (TOC), dissolved organic carbon (DOC) and total particulate organic carbon (T-POC). Water samples were also analysed to determine total bacterial abundance (TBA) and the counts of bacterial rods, cocci and spiral-shaped bacteria, and sulphate-reducing bacteria (SRB). Significant variations in odour intensity were noted between years and sampling sites. Odour was significantly determined by the proportion of lake water in river water. It was also significantly correlated (P&lt;0.01, P&lt;0.001) with most of the analysed physicochemical and microbiological parameters. The multiple regression analysis revealed that odour intensity was influenced directly by TOC and DN and indirectly by H2S, NH4-N, TBA and counts of SRB,  rod- and spiral-shaped bacteria only in.</p

Amaranth Meal and Environmental Carnobacterium maltaromaticum Probiotic Bacteria as Novel Stabilizers of the Microbiological Quality of Compound Fish Feeds for Aquaculture

Fish feed should be characterized by microbiological stability to guarantee the optimal health of farmed fish. The aim of this study was to determine the efficacy of amaranth meal (Amaranthus cruentus) and a highly active environmental strain of probiotic bacteria, Carnobacterium maltaromaticum, as novel supplements that stabilize the quantitative and qualitative composition of microbiota in compound fish feeds for aquaculture, regardless of storage temperature. The total viable counts of mesophilic bacteria at 28 &deg;C (TVC 28 &deg;C), hemolytic mesophilic bacteria (Hem 37 &deg;C), Staphylococcus sp. bacteria, aerobic spore-forming bacteria (ASFB), sulfite-reducing anaerobic spore-forming Clostridium sp. bacteria, yeasts, and molds were analyzed in control feed (CF), in feed supplemented with amaranth meal (AF), and in feed supplemented with amaranth meal and C. maltaromaticum (ACF), stored at a temperature of 4 &deg;C and 20 &deg;C for 98 days. Amaranthus cruentus and C. maltaromaticum significantly reduced bacterial counts in fish feeds, regardless of the temperature and duration of storage. The antibacterial and antifungal effects of the tested additives were statistically significant (p &le; 0.05). The studied novel supplements contribute to the microbiological safety of compound fish feeds. The tested additives could be recognized as the key ingredients of organic, environmentally friendly fish feeds, which guarantee the high quality of fish intended for human consumption