Connection between the gut microbiota of largemouth bass (Micropterus salmoides) and microbiota of the aquaponics system environment.

The significant role played by the gut microbiota in fish growth, development, immunity, and overall health has been widely established. Nevertheless, there remains a lack of clarity regarding the interaction and origin between the environmental microbiota and the gut microbiota of aquaculture species within the aquaponics coupling system. Thus, we conducted an analysis of the gut microbiota of largemouth bass (Micropterus salmoides) obtained from an indoor enclosed circulating water aquaponics coupling system located in greenhouses in northern China. Additionally, we examined the microbiota of the fish pond water and tomato rhizosphere soil using high-throughput sequencing of the 16S rRNA gene. Our results demonstrated significant differences in the compositions of fish pond water, rhizosphere soil, and the gut microbiota of largemouth bass. Moreover, these compositions changed throughout the culture period. Approximately 11.99% of the bacterial composition in the gut microbiota of largemouth bass could be attributable to the rhizosphere soil microbiota, while 62.01% of the bacterial composition could be attributable to the fish pond water microbiota. However, the proportion of bacteria in the gut microbiota from the fish pond water microbiota remained respectively 40.90% and 56.15% in May and September, which increased markedly to 88.97% in July. Similarly, the proportion of bacteria in the pond water microbiota from the tomato rhizosphere soil microbiota were respectively 0% and 8.95% in samples collected in May and September, which increased markedly to 69.26% in July, and the proportion of bacteria in the gut microbiota from the tomato rhizosphere soil microbiota were respectively 0.07% and 0% in samples collected in May and September, which increased to 0.45% in July. The research results offer essential insights into the interactions and origins of environmental microbiota and gut microbiota in the aquaponics system of cultured fish. This knowledge could enhance green aquaponics practices for largemouth bass.

Anaerobic degradation of excess protein-rich fish feed drives CH4 ebullition in a freshwater aquaculture pond.

Aquaculture is a climate-relevant source of greenhouse gases like methane. Methane emissions depend on various parameters, with organic matter playing a crucial role. Nevertheless, little is known about the composition of organic matter in aquaculture. We investigated the effects of excessive loading of high-protein fish feed on the quality of sediment organic matter in a fishpond to explain extremely high methane ebullition rates (bubble flux). Analysing the molecular composition of water-extractable organic matter using liquid chromatography Fourier-transform ion cyclotron resonance mass spectroscopy, we found strong differences between the feeding area and open water area: low-molecular weight nitrogen and sulphur-rich organic compounds were highly enriched at the feeding area. In addition, methane ebullition correlated well with sediment protein content and total bound nitrogen in pore water. Our results indicate that feed proteins in the sediments are hydrolysed into oligopeptides (CHNO) and subsequently converted to CHOS and CHNOS components during anaerobic deamination of protein and peptide fragments in the presence of inorganic sulphides. These metabolites accumulate at the feeding area due to continuous feed supply. Our findings illustrate the adverse effects of excessive feeding leading to bioreactor-like methane emissions at the feeding area. Improving feed management has the potential to make aquaculture more climate-friendly.

CH4 and CO2 emissions in water networks of rice cultivation regions.

Rice cultivation regions have a high density of open water networks to meet the requirements of rice growth and production. These open water networks have a significant risk of carbon (C) emissions due to agricultural production, but the C emissions from these waters are not clearly recorded in previous studies. Therefore, this study aimed to explore the pattern and internal mechanism of methane (CH4) and carbon dioxide (CO2) emissions from multiple types of waters (i.e., river, fish pond, reservoir, and ditch) in a typical rice cultivation region in southwestern China. The annual CH4 and CO2 fluxes were higher in the downstream river (2.79-94.89 and 39.39-1699.98 mg m-2 h-1) and ditch (8.80-74.99 and 123.43-542.65 mg m-2 h-1, respectively) and lower in the reservoir (-0.67 to 3.45 and -239.15 to 141.50 mg m-2 h-1) (P < 0.05). The monthly trends of CH4 and CO2 fluxes from the middle river and ditch were driven by interactive reactions of rice cultivation practices and precipitation. In contrast, the emission patterns of CH4 and CO2 from the lower river, upper river, and fish pond were mainly driven by domestic sewage discharge, precipitation, and aquaculture practices, respectively. This study suggested that river and ditch were more sensitive to C emissions than other waters, and the rice production period was the critical period for controlling C emission. Although rice paddy soils yield more cumulative emissions of CH4, water networks in rice cultivation regions were possible hotspots for C emissions due to the higher emission intensities, which were largely overlooked before. Thus, it is necessary to refine and promote practices to better mitigate C emissions from waters in rice cultivation regions in the future.

Characteristics of microplastic pollution and analysis of colonized-microbiota in a freshwater aquaculture system.

The microbial communities associated with microplastics (MPs) and their ambient environments have received wide attention. Although previous studies have reported the differences of microbial communities between MPs and natural environment or substrates, the effects of MPs on microbial balance and functions in ambient water remain unclear, particularly for aquaculture water. Here, we investigated the MPs pollution in farm ponds of grass carp located in the Foshan City of Guangdong Province and reported the distinction of bacterial structures, functions, and complexity between microbiota on MPs and in water. MPs with an average abundance of 288.53 ± 74.27 items/L in pond water were mostly fibers and cellulose, mainly transparent and in size of 0.5-1 mm. Structures and functions of bacterial communities on MPs significantly differed from that in pond water. A large number of enriched or depleted OTUs on MPs compared with water belong to the phylum Proteobacteria, the predominant phylum in microbial communities on MPs and in water. Some species included in the phylum Proteobacteria have been shown to be cellulose-degrading and pathogenic. Microbiota on MPs exhibited higher species richness and diversity as well as a more complex network than that in water, illustrating MPs as a distinct habitat in the aquaculture system.

Pesticide contamination of fish ponds in relation to crop area in a mixed farmland-pond landscape (Dombes area, France).

Pesticides are still widely used by agriculture, leading to the exposure of surface water. This may be the case for fish ponds located in farmland landscapes. To address this issue, the present study investigated the contamination by pesticides of fish ponds located in the mixed agriculture-pond landscape of the Dombes area, France. Ten ponds were selected in water catchments with a gradient of 3-57 ha of cropland with maize and winter cereals as the dominant crops. A total of 197 water samples were collected in the ponds during the fish production season over 3 years. Recently used pesticides were the most frequent residues occurring. Occurrences greater than 0.1 µgL-1 particularly concerned chlorotoluron and S-metolachlor. Maximum observed concentrations were slightly above 3 µgL-1 for S-metolachlor, acetochlor, and dimethenamide, all herbicides allowed for maize cultivation. Isoproturon and chlorotoluron, herbicides allowed in cereal crops, reached up to 1.2 and 1.0 µgL-1, respectively. We found a significant positive effect of crop area in catchments on the pond contamination frequency by pesticides and more significantly on the contamination frequency by broad-spectrum herbicides (glyphosate and AMPA residues). The cumulative antecedent rainfall was best correlated to the frequency of highest contaminations (> 0.5 µgL-1). In such a hydrological context, the crop area within catchment was identified as a good indicator of fish pond exposure to pesticide residues. Finally, we proposed to adapt some mitigation measures to reduce fish pond contamination.

An application study of membraneless-gas separation microfluidic paper-based analytical device for monitoring total ammonia in fish pond water using natural reagent.

The membraneless-gas separation microfluidic paper-based analytical device (ML-GS µPAD), consisting of donor, spacer, and acceptor layers, was developed to monitor total ammonia in fish pond water. The principle of the analysis involved the addition of sodium hydroxide solution to the sample zone in the donor layer containing ammonia/ammonium, and the produced ammonia gas diffuses through the spacer to the detection zone in the acceptor layer containing red rose extract to produce a color change from pink to blue corresponding to the ammonia/ammonium concentration. Under optimum conditions, the proposed method provided good linearity of ammonia in the range concentration of 0-100 mg L-1 (R2 = 0.9993) with LOD and LOQ of 2.25 and 7.51 mg L-1, respectively. This method was successfully applied to fish pond water samples without significant influence of interfering compounds with recoveries in the range of 103-110%, indicating good selectivity and accuracy of the proposed method.

Shifts in structure and function of bacterial community in river and fish pond sediments after a phenol spill.

Phenol is widely used in industrial processes and has microbial toxicity. However, the effects of a phenol spill on the microbial community are not clear. The present study explored the changes of bacterial communities in river and fish pond sediments after a phenol spill. The bacterial richness and diversity in river sediments were lower on day 30 (36 days after the spill) than on day 0, while they increased in fish pond sediments. The structures and functions of bacterial communities in both river and fish pond sediments were changed, and a more dramatical variation was detected in fish pond sediments. In river sediments, Proteobacteria, Chloroflexi, Acidobacteria, Bacteroidetes, and Nitrospirae were the major bacterial phyla, and Chloroflexi was enriched. In fish pond sediments, genera Brevibacillus dominated bacterial communities initially, and bacterial composition showed a dramatic change on day 30. Most predicted metabolism functions, as well as genetic information processing functions of translation, replication, and repair, were enhanced in both river and fish pond sediments, while they showed an opposite change trend for xenobiotic degradation function. This work could strengthen our understanding of the effects of phenol spills on sediment bacterial communities in both lotic and lentic ecosystems.

Development of an android app for estimating the water quality parameters in fish pond.

In this research, a new android app for smartphones for estimating some water quality parameters in carp fish ponds such as pH, electrical conductivity (EC), total dissolved solids (TDS), and turbidity is presented. Contact imaging was used to acquire images from the samples. To estimate pH, EC, TDS, and turbidity values, 12 features were extracted from each image. Features were used as input to the artificial neural network models. The performance of the models was evaluated by the R2 and RMSE parameters. Based on the results, the network with a structure of 12-15-4 was selected as the best model. The values of R2 for estimating pH, TDS, EC, and turbidity were 0.913, 0.993, 0.994, and 0.958, respectively, while the corresponding values for the RMSE were 0.054, 1.835, 3.766, and 0.262, respectively. Finally, this model was successfully implemented on an app named WaterApp on the android smartphone. For testing the app on the smartphone, the performance of the model was evaluated again using new images. According to the results, the R2 values for validation data by the developed WaterApp for pH, EC, TDS, and turbidity were 0.88, 0.913, 0.884, and 0.944, respectively.

Fish pond water treatment using ultrasonic cavitation and advanced oxidation processes.

This investigation explores the efficacy of employing ultrasonic cavitation and coupling it with advanced oxidation processes (hydrogen peroxide and Fenton's reagent) for reducing the levels of total ammonia nitrogen in fish pond water containing Tilapia fishes. Ultrasonic cavitation is a phenomenon where the formation, growth and collapse of vaporous bubbles occur in a liquid medium producing highly reactive free radicals. Ultrasonic probe system (20 kHz with 750 W and 1000 W) was used to induce cavitation. Besides, to intensify the process, ultrasonic cavitation was coupled with hydrogen peroxide and Fenton's reagent. Using SERA colour indicator test kits, the levels of ammonium, nitrite and carbonate hardness were measured. The results obtained from this study clearly show that the advanced oxidation processes are more efficient in reducing the ammonium and nitrite levels in fish pond water than using ultrasound alone. The pH and carbonate hardness levels were not affected significantly by ultrasonic cavitation. The optimal treatment time and ultrasound power to treat the water samples were also established. Energy efficiency and cost analysis of this treatment have also been presented, indicating that ultrasonic cavitation coupled with hydrogen peroxide appears to be a promising technique for reducing total ammonia nitrogen levels in the fish pond water.

Identification of microplastics in fish ponds and natural freshwater environments of the Carpathian basin, Europe.

In the past few years, there has been a significant development in freshwater microplastic research. Pollution has been detected in lakes and rivers of several continents, but the number of papers is still marginal compared to the ones investigating marine environments. In this study, we present the first detection of microplastics (MPs) in Central and Eastern European (CEE) surface waters and, globally, the first detection in fish ponds. Samples were taken from different types of fish ponds and natural water bodies along a novel concept down to a particle size of 100 µm, then, after sample preparation, MPs were characterized using an FTIR microscope. 92% of the water samples contained MPs ranging from 3.52 to 32.05 particles/m3. MPs were detected in 69% of the sediment samples ranging from 0.46 to 1.62 particles/kg. Dominant abundance of polypropylene (PP) and polyethylene was shown in water and PP and polystyrene in sediment samples. First results also indicate that fish ponds may act as a deposition area for MPs.

Assessing the cellulase enzyme heterogeneity of bacterial strains and their feedback to cattle manure degradation in a greenhouse model of in vivo pond ecosystem.

The responses of cellulase enzymes of three bacterial isolates and their impacts on cattle manure decomposition were assessed in a greenhouse model in vivo pond ecosystem. Fifty grams of fresh cattle manure was placed in a fastened nylon bag (mesh size ~ 50 µm dia.) and placed in triplicate in a plastic bucket with 10 l of pond water which was hung inside the enclosed polyhouse, semi-closed and open systems for 4 weeks. Samples of manure residue directly from nylon bag and water from manure leached bucket water, water, and soil from the enclosed polyhouse were collected for enzymatic assays, enumeration of aerobic cellulose decomposing and heterotrophic bacteria, and determination of water and soil quality parameters. Responses of cellulases to different temperatures in situ were also elucidated. The values of test bacteria, endoglucanase, exoglucanase and ß-glucosidase, and organic carbon were significantly (P Ë‚ 0.05) higher in the closed system compared to semi-closed or open system. Priming of all the enzymes coupled with the peak of aerobic cellulose decomposing bacteria and heterotrophic bacterial populations occurred on the day 14 or 21 in vivo. Since the peaks of three cellulases of bacterial isolates (KUPH1, KUPH6, and KUPH8) were demonstrated between 35 and 40 °C, and that temperature coincided with temperature of the greenhouse model, this temperature range appeared to favor the growth of cellulose decomposing bacterial populations and involved cellulase enzymes.

Composition and bioaccessibility of elements in green seaweeds from fish pond aquaculture.

The elemental composition of five species of green seaweeds (Chaetomorpha linum, Rhizoclonium riparium, Ulva intestinalis, Ulva lactuca, Ulva prolifera) grown in fish pond aquaculture systems were studied. The elemental bioaccessibility in these species was also investigated through the application of an innovative in vitro digestive model of the human gastrointestinal tract. It was observed that R. riparium had the highest levels of Mn, Sr, Cd, Sn, and I and that U. lactuca had the highest Ni and Cu concentrations. The daily amounts of dried green seaweed required for achieving specific dietary intakes were calculated, namely: 7g of dried U. lactuca (for meeting Cu Recommended Daily Allowance, RDA); 173g of dried U. lactuca (Zn RDA); 78g of dried C. linum (Se RDA); 41g of dried C. linum (Mo RDA); and 0.5g of dried R. riparium (I Dietary Reference Intake, DRI). Concerning elemental bioaccessibility, Mn and Cu had the highest values, always above 50%, I values were in the lower range, between 14 and 31%. The elemental bioaccessibility range of R. riparium (31-100%) was higher than the ranges for other species, particularly C. linum (0-56%). The bioaccessibility results entailed higher quantities of dried seaweed for reaching dietary intakes: 10g of dried U. lactuca (Cu RDA); 290g of dried R. riparium (Zn RDA); and 2g of dried R. riparium (I DRI). Accordingly, R. riparium is a very rich I source. This study showed the importance of taking into account bioaccessibility results in estimating dietary intakes.

Fatty acid profiles of the main lipid classes of green seaweeds from fish pond aquaculture.

The lipid composition of five species of green seaweeds (Chaetomorpha linum, Rhizoclonium riparium, Ulva intestinalis, Ulva lactuca, and Ulva prolifera) grown in fish pond aquaculture systems was studied. In particular, the overall fatty acid (FA) profile and the FA profile of each main lipid class found in these seaweed species were thoroughly analyzed. It was found that every seaweed had a specific FA profile, whose specificities were rendered more obvious with the study of the FA profile per lipid class. However, between U. lactuca and U. intestinalis, there were only minor differences. Nonetheless, it was possible to identify significant differences between the palmitic acid content in the phospholipid (PL) and glycolipid (GL) classes of each seaweed. A clear distinction between the FA profiles of R. riparium and C. linum, which belong to the Cladophorales order, and those of Ulva genus, Ulvales order, was also determined. Moreover, there were also differences among lipid classes, yielding large contrasts between PLs + GLs and triacylglycerols (TAGs) as well as between monoacylglycerols (MAGs) and free fatty acids (FFAs). This study also found evidence supporting the location of particular FAs in specific TAG positions. FA profiles have the potential to be used as a chemotaxonomic tool in green seaweeds, providing a simple method to check authenticity of seaweed used as food.

Determination of five endosulfan pesticides in the fish pond water by dispersive liquid-liquid microextraction combined with GC-MS.

A simple and rapid dispersive liquid-liquid microextraction (DLLME) technique coupled with gas chromatography-ion trap mass spectrometry (GC-MS) was developed for the extraction and analysis of five endosulfan pesticides from the fish pond water. In this work, different parameters affecting the extraction process such as the type and volume of extraction solvent, type and volume of disperser solvent, and extraction time were studied and optimized. Under optimized conditions, the enrichment factor ranged from 189 to 269 and the relative recovery ranged from 88.5% to 94.9%. The linear range was 2.0-80.0 µg/L; the limits of detection and quantitation were in the range 0.04-1.06 µg/L and 0.12-3.53 µg/L, respectively. The relative standard deviations were in the range 0.94%-2.08% (n = 5). The obtained results show that DLLME combined with GC-MS is a fast and simple method for the determination of endosulfan pesticides in fish pond water.

Composition, diversity and short-term temporal fluctuations of zooplankton communities in fish culture ponds (Pindamonhangaba), SP / Composição, diversidade e flutuações temporais de curto prazo da comunidade zooplanctônica de viveiros de piscicultura (Pindamonhangaba), SP

The present study aimed at evaluating the composition, diversity and short-term temporal fluctuations of zooplankton communities in fish ponds. The study was carried out in two fish ponds, with 180 m² of water surface (6 × 30 m) each, located in the Aquiculture Centre of the Pindamonhangaba Fisheries Institute - São Paulo. The study was developed over eight weeks, from February 16 to April 6, 1998. The physical and chemical conditions of the water in the fish ponds were adequate for zooplankton development. The zooplanktonic community was characterised by high richness of species and a greater diversity was observed in the first fish pond, with a superior density of Rotifera. Temporal changes in zooplankton composition occurred in both ponds with Cladocera appearing in abundance later, in the fourth week, whereas copepods and rotifers were well represented since the beginning. Many species found are typical of fish ponds and are considered to constitute an excellent food source, showing high nutritional value for fish larvae, a good example being individuals from the Rotifera group and the micro-crustacean species Moina minuta and Thermocyclops decipiens.

O presente estudo visou avaliar a composição, a diversidade e a flutuação do zooplâncton em dois viveiros escavados na terra com 180 m² de espelho d'água (6 × 30 m) cada um, no Núcleo de Aquicultura do Instituto de Pesca de Pindamonhangaba-SP. O estudo foi realizado durante oito semanas, no período de 16 de fevereiro a 6 de abril de 1998. As condições observadas, em relação às características físicas e químicas da água dos viveiros, foram adequadas ao desenvolvimento dos organismos zooplanctônicos. A comunidade zooplanctônica foi caracterizada por elevada riqueza de espécies, com maiores densidades de organismos pertencentes ao grupo Rotifera. Mudanças temporais na composição do zooplâncton ocorreram em ambos os tanques, com Cladocera aparecendo em maior abundância mais tarde, na quarta semana, enquanto que copepodos e rotíferos foram bem representados desde o início. Muitas espécies encontradas são típicas de viveiros de piscicultura e constituem excelente fonte alimentar, apresentando alto valor nutritivo para larvas de peixes, como por exemplo os indivíduos do grupo Rotifera e as espécies Moina minuta e Thermocyclops decipiens.