Fish Farm Facilities Research Articles

Results of iodine-based treatment application in carp aquaculture within closed water systems

The study aimed to monitor the prevalence of ectoparasites and bacterial infestations in carp and to determine effective dosages of a new iodine-based treatment for disease prevention. The research found that carp were affected by ectoparasites G. kobayashii at 43.32%, L. cyprinacea at 46.67%, and P. lusiana at 31.71% in fish farming facilities within the Sumy Region. Treatment with the iodine-based product resulted in a reduction of infestation levels to 0.2%, including a decrease in the incidence of gyrodactylosis by 89.92-97.35%, lernaeosis by 79.13-95.91%, and philometroidosis by 81.30-91.16% compared to monitoring results. In investigations of bacterial infestations, it was found that the contamination of carp was higher for E. coli at the PC “Shmatukha” by 8.0%, Aeromonas hydrophila by 47.97%, and Aeromonas salmonicida by 31.39%. Additionally, Pseudomonas anguilliseptica was detected at 19.48%, Streptococcus iniae at 13.27%, and Micrococcus spp. at 38.14% at LLC “Ryasnyanske”. The presence of Staphylococcus aureus was recorded at 21.37%, and Listeria monocytogenes at 11.43% at LLC “Bdzhola”; these figures were lower than those observed in other farms. Following treatment with the iodine-based agent, contamination of fish by E. coli decreased by 98.96% at the PC “Shmatukha”, 99.2% at LLC “Bdzhola”, and 84.32% at LLC “Ryasnyanske”. Contamination of carp by A. hydrophila decreased by 94.51% at the PC “Shmatukha”, 80.28% at LLC “Bdzhola”, and 99.15% at LLC “Ryasnyanske”. The presence of A. salmonicida was reduced by 97.23% at the PC “Shmatukha”, 94.00% at LLC “Bdzhola”, and 79.06% at LLC “Ryasnyanske”. Contamination by S. aureus decreased by 92.15% at the PC “Shmatukha”, 98.74% at LLC “Bdzhola”, and 93.89% at LLC “Ryasnyanske”. The levels of S. iniae decreased by 80.90% at the PC “Shmatukha”, 99.63% at LLC “Bdzhola”, and 83.30% at LLC “Ryasnyanske”. Contamination by L. monocytogenes was reduced by 96.25% at the PC “Shmatukha”, 96.08% at LLC “Bdzhola”, and 98.13% at LLC “Ryasnyanske”. Furthermore, Micrococcus spp. levels decreased by 93.74% at the PC “Shmatukha”, 96.37% at LLC “Bdzhola”, and 92.26% at LLC “Ryasnyanske”, in comparison to the monitoring results. The practical value of this study lies in controlling the spread of ectoparasites and developing preventive measures to eliminate ectoparasites and bacterial infestations in carp prior to their release into water bodies

Smart Low-Cost Control System for Fish Farm Facilities

Smart Low-Cost Control System for Fish Farm Facilities

Salmon farming alters the structure and functioning of Norwegian maerl bed communities

Abstract Effluents resulting from fish farming activities can alter the structure and functioning of benthic ecosystems. In Norway, recent technological advances within the salmon industry have facilitated the expansion of aquaculture into shallower locations, leading to additional pressures upon coastal habitats. Maerl/rhodolith beds are important bioengineers in coastal waters—supporting highly diverse associated macrofaunal communities—and are likely to be particularly at risk. This study aims to investigate the environmental changes induced by fish farms in their vicinity and their impact on the structure and functioning of maerl bed macrofaunal communities. High dissolved nutrients and organic enrichment levels were observed close to the cages, associated with lower live maerl cover. Overall, the most substantial impact of salmon farms on macrofaunal communities was observed within 100 m from the cages. Nevertheless, changes in the structure and functioning of assemblages were evidenced up to 300 m. In the vicinity of the cages, communities were characterized by the dominance of endobenthic subsurface deposit feeders and opportunistic species, notably the polychaetes Chaetozone sp., Capitella sp. and Scoloplos armiger. Conversely, sites situated farther away from the cages exhibited higher abundances of epibenthic taxa, including crawlers, grazers and species sensitive to organic enrichment. Sites unaffected by the presence of fish farms were described by high abundances of the ophiuroid Ophiura robusta, the polychaete Proclea graffi and ostracods, reflecting more favourable environmental conditions. Such changes in macrofaunal communities highlight the vulnerability of maerl beds to the impacts of aquaculture, thus emphasizing the importance of rigorous site selection when establishing new fish farming facilities.

Trajectories of trace element accumulation in seagrass (Posidonia oceanica) over a decade reveal the footprint of fish farming

To evaluate the effect of trace element (TE) release from fish farms on seagrass Posidonia oceanica, we compared TE concentrations (As, Cd, Co, Cu, Mn, Mo, Ni, Pb, V, Zn) in shoots near fish cages (Station ‘Cage’) with those away from them (Station ‘Control’) in two fish farm facilities (Site 1 and Site 2, North Aegean Sea, Greece). We assessed the present (i.e., 2021, year of sampling) and past (reconstructed period 2012–2020) accumulation of TEs using the living compartments (leaf blades, sheaths, rhizomes, roots, epiphytes) and the dead sheaths, respectively. We also assessed possible seagrass degradation by reconstructing past rhizome production. P. oceanica rhizome production at the ‘Cage’ stations was up to 50% lower than at the ‘Control’ stations. Most TE concentrations were higher at ‘Cage’ stations, but the differences often depended on the seagrass living compartment. Significant differentiation between ‘Cage’ and ‘Control’ stations was observed based on the TE concentrations of the dead sheaths during 2012–2020. The contamination level at the ‘Cage’ stations was mostly moderate in Site 1 and low in Site 2, during the reconstructed period, while an increasing contamination trend was found for certain potential phytotoxic TEs (As, Cu, Cd, Mo, V). Our results emphasize the need for the aquaculture industry to work towards a more ecologically aware approach.

Biodegradability and bioavailability of dissolved substances in aquaculture effluent: Performance of indigenous bacteria, cyanobacteria, and green microalgae

Aquaculture is a controlled aquatic farming sector and one of the most important human food sources. Fish farming is one of the predominant, fast-growing sectors that supply seafood products worldwide. Along with its benefits, aquaculture practices can discharge large quantities of nutrients into the environment through non-treated or poorly treated wastewater. This study aims to understand the nutrient composition of fish wastewater and the use of indigenous bacteria, cyanobacteria, and microalgae as an alternative biological treatment method. Wastewater samples from a local fish farming facility were collected and treated using six different species of cyanobacteria and microalgae include Chroococcus minutus, Porphyridium cruentum, Chlorella vulgaris, Microcystis aeruginosa, Chlamydomonas reinhardtii, and Fischerella muscicola. All the samples were incubated for 21 days, and the following parameters were measured weekly: Chemical oxygen demand (COD), phosphate, total dissolved nitrogen, and dissolved inorganic nitrogen. In addition, dissolved organic nitrogen (DON), bioavailable DON (ABDON), and biodegradable DON (BDON) were calculated from the mass-balance equations. Colorimetric and digestive methods were used for the parameter measurements. The results showed that C. reinhardtii reduced the soluble COD concentration by 74.6 %, DON by 94.3 %, and phosphorous by more than 99 %. Moreover, M. aeruginosa, and C. minutus significantly reduced inorganic nitrogen species (>99 %). This alternative fish wastewater treatment method was explored to gain insight into fish wastewater nutrient composition and to create a sustainable alternative to conventional fish wastewater treatment methods.

Development of a hybridized small modular reactor and solar-based energy system for useful commodities required for sustainable cities

The current study develops a hybridized small modular nuclear reactor and solar-based system designed specifically for sustainable communities in metropolitan areas to meet their power, heat, clean fuel, fresh water and food requirements. Both floating-type and bifacial-type photovoltaic arrays are integrated with a high-temperature gas-cooled small modular reactor. In the integrated system, a Rankine cycle subsystem for power generation, a solid oxide electrolyzer for hydrogen production, a pressure swing adsorption unit with ammonia reactor for nitrogen and then ammonia production, a multi-effect desalination unit for freshwater generation, and heat recovery units in order to provide heating to residential area, food drying facility, greenhouse, and fish farm facilities. For both floating and bifacial PV options, the 120 MWp PV modules are considered and integrated with two small modular reactor units at 250 MWth capacities each, 500 MWth in total. A thermodynamic analysis, which is based on energy and exergy approaches, is carried out. The time-dependent analyses are carried out for floating-type PV and bifacial-type PV options for the cities of Istanbul in Turkey; Barcelona in Spain; Los Angeles (LA) in the United States; Tokyo in Japan; and Toronto in Canada by using their hourly meteorological data, source and load capacities in a typical meteorological year. Among ten cases, between 112835 and 146180 tonnes of ammonia are generated in a typical year while meeting the heating and power requirements of sustainable communities in metropolitan areas. Among ten cases, the average overall energy and exergy efficiencies are found as 41.04% and 46.88%, respectively. The hybridization of such nuclear and solar systems achieves unique advantages by preventing intermittencies compared to the renewable-alone systems, reducing carbon emissions compared to fossil-based systems, and lowering the levelized costs of energy compared to the nuclear energy-alone systems.

Tracking Microbial Diversity and Hygienic-Sanitary Status during Processing of Farmed Rainbow Trout (Oncorhynchus mykiss).

Aquaculture is becoming a strategic sector for many national economies to supply the increasing demand for fish from consumers. Fish culture conditions and processing operations can lead to an increase in microbial contamination of farmed fish that may shorten the shelf-life of fish products and byproducts, and ready-to-eat fishery products. The objective of this study was to evaluate the hygienic-sanitary status of water, environment, and processing of fresh-farmed rainbow trout (Oncorhynchus mykiss) fillets produced in a local fish farm in Andalusia, Spain. To achieve this, a longitudinal study was carried out by collecting environmental (air and food-contact surfaces), water from fish ponds, and rainbow trout samples. Thereby, seven sampling visits were performed between February 2021 and July 2022, where foodborne pathogens and spoilage microorganisms, together with physicochemical parameters, were analysed in the collected samples. Further, microbial identification of microbiota was achieved through a culture-dependent technique using blast analysis of 16S RNA gene sequencing. The results showed that Listeria monocytogenes and Salmonella were not detected in the analysed samples. Regarding the hygienic-sanitary status of the fish farm, the slaughtering bath, the eviscerating machine and the outlet water from fish ponds presented the highest counts of coliforms, Enterobacteriaceae, and Aerobic Mesophilic Bacteria. Staphylococcus aureus and sulphite-reducing Clostridium were identified in the conveyor belts, fish flesh, and viscera. The 16S RNA identification confirmed the presence of viable spoilage bacteria such as Citrobacter gillenii, Macrococcus caseolyticus, Hafnia paralvei, Lactococcus lactis, Lactococcus cremoris, Klebsiella, Escherichia coli, Morganella morganii, and Shewanella. Three of these genera (Citrobacter, Hafnia, and Pseudomonas) were present in all types of samples analysed. The results evidenced potential transmission of microbial contamination from contaminated packaging belts and boxes, evisceration and filleting machines to flesh and viscera samples, thus the establishment of control measures should be implemented in fish farm facilities to extend the shelf-life of farmed fishery products.

Current state of ichthyofaauna and prospects for fishing use of lake Ak-School of Zharma district of east Kazakhstan region

The research work was carried out in the spring period in May 2022. The article deals with the formation of the fish population and the study of the current state of commercial fish species in the Ak-School lake located in the Zharma district of the East Kazakhstan region for the subsequent effective development of fish farming. As a result of the work carried out, 4 species — roach, perch, tench, pike. Modern data were obtained on the main biological indicators of fish, such as body length, body weight and sex ratio. According to the results of the research work, the prospects of economic use of the studied reservoir are indicated. For Lake Ak-Shkola, the recommended species for cultivation is carp carp in a polyculture with white cupid and white carp by intensive cultivation method. The research work was carried out within the framework of the project “Development and implementation of effective biotechnical techniques for conducting commercial fish farming in various regions of Kazakhstan”, under the scientific and technical program “Scientific and technological support for the integrated development of aquaculture in Kazakhstan through the development and implementation of innovative technologies and new fish farming facilities”, under the section “Development and implementation effective biotechnical methods of conducting lake-commercial fish farming in the East Kazakhstan region” (hereinafter the project). The study is funded by the Ministry of Ecology, Geology and Natural Resources of the Republic of Kazakhstan (IRN — BR10264236).

Inclusion of cocoa shell flour (Theobroma cacao L) in the diet of (Oreochromis spp)

The research was carried out at the Socio Tilapia fish farm facilities; via Quevedo, Santo Domingo, Los Ríos province, at an altitude of 100 meters above sea level, to determine the inclusion of cocoa shell flour in the fish farming process (Theobroma cacao L) as an alternative protein source in intensive tilapia farming (Oreochromis spp). The sample size consisted of 128 fish, with 8 experimental units per cage, fed for 42 days, with the inclusion of cocoa shell meal levels (0, 4, 8, and 12%), in four treatments and four replicates, with commercial pelleted concentrate as control; an experimental design (DCA) was used, with multiple comparison measures according to Tukey's test (P < 0.05). The results in all variables had a better performance in the T3 treatment (12% cocoa shell meal), without affecting any parameter, obtaining better results for feed conversion (1.45%), weight gain (24.05%), feed consumption (675.06 g) and total length with an average of (1 cm) corresponding to the days of investigation of the 32 experimental units. It was established that in fillet yield and carcass yield there is a usable value, 47.49 %, and 95.42 %, while a lower value in the by-products, 54.65 %, respectively.

Fish farming facilities for cultivation in agricultural reservoirs with intense hydrochemical regime

Agricultural reservoirs built on acidic, swampy soils, peat processing, as a rule, have a tense hydrochemical regime. Overseas phenomena are also a natural consequence of the intensification of pond fish farming. In the hottest time of the year (most often in July, the first half of August), the massive development of phyto-, zooplankton, benthos and, above all, microorganisms (bacteria), compaction of fish planting for cultivation, intensive feeding with artificial feeds, lead to the accumulation of organic matter and a sharp decrease in oxygen content in water. One of the ways to develop such lands is to expand the number of breeding facilities with increased resilience. Widespread, the most hardy, having high nutritional qualities of fish — golden and silver crucian carp, as well as their hybrids have considerable commercial value in reservoirs of various origins and conditions, especially unfavorable hydrochemical regime. A promising object is the snakehead. This is a predatory freshwater Far Eastern fish, which is characterized by rapid growth and has high-quality meat. It breathes both at the expense of oxygen dissolved in water, and at the expense of atmospheric air, for breathing which it has a gill organ. The snakehead cannot exist only due to water respiration by gills. It feeds at a young age mainly on crustaceans and insects. As they grow, more and more switch to fish food, and large specimens feed almost exclusively on fish and frogs. In reservoirs with a tense hydrochemical regime, due to its unpretentiousness and undemanding to oxygen, tench can be grown. Tench is a promising object for breeding and stocking reservoirs. It is unpretentious, undemanding to water quality, can live in reservoirs with a very low oxygen content (up to 0.3 ml/l), a heavily silted bottom and acidic water, tolerating a decrease in pH to 5.

ISOLATION OF STRAINS ANTAGONISTIC TO PATHOGENIC AEROMONADS FROM NATURAL POPULATIONS OF FISH AND BOTTOM SEDIMENTS

Increasing production efficiency and ensuring the environmental safety of commercial fish farming facilities through the creation of modern preparations for the treatment and prevention of diseases is a topical area of aquaculture. The study of the current situation shows that the factors limiting the possibilities of sustainable entry to the market, providing fish farms with high-quality highly productive breeding material and increasing the volume of commercial fish farming products are diseases of the breeding facilities. The development of new highly effective probiotic preparations for the prevention and treatment of aquaculture facilities will not only reduce the economic costs associated with the death of breeded fish, but will also help to increase the viability of fish, the accumulation of nutrients in tissues, and the correction of the microbiocenosis of the aquatic environment. The aim of the study is to search for natural Bacillus antagonistic strains promising for creating probiotics. The strains were isolated from bottom sediments and cyprinids of natural populations. In the course of the work, the antimicrobial spectrum of action of bacilli against the causative agents of aeromonosis, furunculosis and bacterial hemorrhagic septicemia (BHS) was studied. Aeromonas test-strains were isolated from sterlet, sturgeon, stellate sturgeon, trout, carp, grass carp, silver carp, grown in conditions of pond farms.

Non-intrusively estimating the live body biomass of Pintado Real® fingerlings: A feature selection approach

Aquaculture has undergone significant technological advances in recent decades, which has enabled the expansion of fish protein production worldwide. However, some conventional processes in fish farming facilities, such as the weighing of fingerlings, usually occur manually and laboriously, which can cause physical damage to the fingerlings, precision balance errors, and financial losses for fish farmers. The main contribution of this research is the creation of an automatic weighing application for fingerlings and juveniles, in contrast to the laborious manual weighing that occurs particularly in small and medium aquaculture facilities. This paper presents results for the prediction of biomass of moving live fingerlings using supervised learning algorithms. It is applied in two new datasets, the first with illumination and the second without illumination. For both datasets, the images are pre-processed and segmented to extract the characteristic vectors systematically trained with cross-validation by four regression algorithms. So, the selection of attributes was performed based on correlation and relative importance which allowed the removal of some attributes which implied null significance for the model. The best result was for the experiment with attribute and frame selection applied to the lighting dataset and the Linear Regressor obtained a R2 = 0.76 and MAE = 0.83 g. The proposed model shows as promising in comparison with other approaches in the literature.

Effect of oxygen micro-bubble for the temperature and oxygen concentrations of fish farming facility

Effect of oxygen micro-bubble for the temperature and oxygen concentrations of fish farming facility

Influence of aquaculture waste on fatty acid profiles and gonad maturation of wild fish aggregations at fish farms

Wild fish belonging to four species belonging to different trophic groups were captured at three distances from fish farm facilities: long distance (>5 Km), medium distance (1.5 Km) and close to sea-cages. Flesh, brain, liver and gonads were sampled for fatty acid analysis. Fish aggregated near sea-cages showed accumulation of fatty acids of vegetable origin in the studied tissues, due to surplus feed consumption or via predation of fish that consumed the feed. Gonads accumulated vegetable fatty acids in different manner in the different species, and the species least and most influenced by fish-feeds were selected for gonad histological examination. Results showed an acceleration of the final stages of the oocyte development in fish aggregated near fish farms compared to fish captured at long distance. Differences in oocyte development were more acute in the species which incorporated higher quantities of vegetable fatty acids.

Mollusk Shell Debris Accumulation in the Seabed Derived from Coastal Fish Farming

Fish farm facilities become colonized by biofouling, and in situ cleaning activities may increase the accumulation of biofouling, mostly shell-hash, on the sediment. However, there is a lack of knowledge about the effect of fish farming on this process. We evaluated the effect of fish farming on shell-hash accumulation on sediments in three fish farms in the Western Mediterranean in Spain. On the one hand, coverage of non-degraded shell on the seabed was estimated using an underwater camera attached to a frame of 1 × 1 m. On the other hand, superficial sediment samples were taken by a Van-Veen grab, and from a subsample, shell-hash was sorted at the laboratory, dried, and weighted. A significant increase of shells on sediment was detected under fish farms compared with the other treatments, with average values of 53 g kg-1, and 1.12% of cover. Shell-hash at zones close to the fish farm cages (Zone of Influence located between 40 to 60 m from the closest cage) did not show statistical differences compared to the reference zones, 300–500 m away from the concession limits, but the shell cover showed statistical differences. Fish farming activities produce a local increase in the sedimentation rate of shells under the cages. The derived ecological consequences of this accumulation need to be further studied.

Application of a new protocol to evaluate the benthic impacts of aquaculture: Colonization of experimental units for monitoring by polychaeta

A range of different protocols and indices have been developed in recent years for the definition of Environmental Quality Standards in aquaculture. However, it can be difficult to compare these protocols or indices between different regions or different habitats due to spatial heterogeneity at different scales. We carried out a field study to estimate the effectiveness of experimental units (sediment-filled trays) as an environmental management tool. The experimental units were filled with two different sediments - sand and mud - and placed underneath two fish farm facilities for one month. Using polychaetes to assess the ecological status, AMBI and multidimensional analysis showed clear results, and had further value when combined with sulphide concentrations measures. Sandy experimental units had a greater sensitivity for the detection of organic matter enrichment. The species with the most pronounced responses in the facilities studied were Capitella capitata, Spiochaetopterus costarum, Capitella minima, Pseudopolydora pulchra and Aricidea (Strelzovia) claudiae in the fish farm, and Gallardoneris iberica, Micronephtys stammeri, Sternaspis scutata and Ampharete lindstroemi in the reference area without organic enrichment. Experimental units provide a complete and reliable source of information about the environmental quality status of fish farms, and with further refinement they could be used as a management tool for aquaculture monitoring. Experimental units could be used as a management tool for aquaculture monitoring; data of polychaete recolonization with AMBI and multidimensional analysis showed clear results.

Escapes of non-native fish from flooded aquaculture facilities: the case of Paranapanema River, southern Brazil

Non-native species are a major driver of biodiversity loss. Aquaculture activities play a key role in introductions, including the escape of fishes from fish farm facilities. Here, the impact of flooding due to El Niño rains in 2015/2016 in the Lower and Middle Paranapanema River basin, southern Brazil, was investigated by evaluating fish escapes from 12 fish farms. The flooding resulted in the escape of approximately 1.14 million fishes into the river, encompassing 21 species and three hybrids. Non-native species were the most abundant escapees, especially Oreochromisniloticus (Linnaeus, 1758) and Coptodonrendalli (Boulenger, 1897) (96% of all fish). Only seven native fishes were in the escapee fauna, comprising 1% of all fish. Large floods, coupled with inadequate biosecurity, thus resulted in considerable inputs of non-native fish into this already invaded system.

Blue light-emitting diode light at 405 and 465 nm can inhibit a Miamiensis avidus infection in olive flounder, Paralichthys olivaceus

Although previous studies have shown that blue light emitting-diode (LED) light has photoinactivation activity against bacteria, little is known about its activity against parasites. The objective of this study was to determine the antiprotozoal activity of LED light at 405 and 465 nm and their in vivo efficacies against scuticociliatosis caused by Miamiensis avidus in olive flounder. Briefly, 105 cells ml−1 of M. avidus were exposed to 405 nm, 465 nm, 520 nm, or 640 nm LED to inactivate ciliates. These ciliates were then observed after trypan blue staining, or double staining with propidium iodide (PI) and Annexin V followed by flow cytometry. Additionally, in vivo experiments were performed twice to assess the efficacy of 405 nm LED against M. avidus after olive flounder were challenged with M. avidus by immersion method. Possible harmful effects of blue LED illumination on fish were also observed. LED irradiation at 405 nm and 465 nm, but not at 520 nm or 640 nm, inactivated half of M. avidus population within 6–12 h and 24–28 h, respectively. Flow cytometry analysis revealed that the distribution of 405 nm-exposed ciliates double stained with PI and Annexin V was gradually changed from Annexin-/PI- (live cell) to Annexin+/PI− (early apoptotic cell) section. It was then further moved to Annexin+ - PI+ (late apoptosis or necrosis) section. Relative percent survival (RPS) of fish infected with the scuticociliate was 0% in group exposed to ambient light. It was 60–70% in the group of fish exposed to LED at 405 nm and 30% in the group exposed to LED at 465 nm. To the best of our knowledge, this is first study demonstrating that M. avidus could be killed by LED light illumination due to induction of apoptosis. There were no significant histopathological changes in eyes of fish between control and irradiance with LED at 405 nm, except for the dorsal retina region of 405 nm exposed fish sampled at 14 days. There were no significant differences in plasma cortisol level or expression level of stress-related and biorhythm-related genes (HSP70, melatonin-3, caspase-3) in the kidney. Our results provide insights into possible application of blue LED for treating scuticociliatosis, the most devastating disease in olive flounder farming industry. Significance of this studyThis is the first study to demonstrate that blue LED light irradiation can inhibit a parasitic pathogen, Miamiensis avidus, by inducing apoptosis. Also, photoinactivation by 405 and 465 nm LED can reduce mortality of live flounder due to scuticociliatosis using in vivo experiments without causing any severe side effects or inducing stress responses. Data obtained in this study indicate that such light therapy may have tremendous benefit, although further research is needed before applying such therapy for intensive fish farming and commercial aquarium facility in the future.

Design and development of low cost smart turbidity sensor for water quality monitoring in fish farms

Turbidity monitoring is necessary in many cases and several sensors have been developed for this purpose. However, in some cases to quantify the turbidity it is not enough and its characterization is necessary. In fish farms, the increase of sedimentary or phytoplanktonic turbidity requires different actions to prevent further damages. For this reason, a sensor able to differentiate between turbidity sources is necessary. In this paper, a turbidity sensor able to distinguish different types of turbidity is designed, developed and calibrated. The sensor is based on the Beer-Lambert law and it uses four LEDs as light sources with different wavelengths. The sensing elements are located at 180° of the light sources and consist of a photodiode and a photoresistor, sensitive to infrared and visible wavelengths respectively. For the calibration process different turbidity sources were employed, Isochrysis galbana, Tetraselmis chuii and sediment. The results show that it is possible to determine the turbidity using the infrared light and to characterize the origin of that turbidity with the red light. An algorithm was created in order to create a method to process the data from each sample to obtain the turbidity, the origin of this turbidity and the concentration of the turbidity source. With this algorithm, we can create a smart turbidity sensor for water quality monitoring. Our main application is focused on monitoring the water input in fish farm facilities; however, this smart sensor will be useful in many other areas.

Numerical simulation of fish nets in currents using a Morison force model

For complex flexible structures such as nets, the determination of drag forces and its deformation is a challenging task. The accurate prediction of loads on cages is one of the key steps in designing fish farm facilities. The basic physics with a simple cage, can be addressed by the use of experimental studies. However, to design more complex cage system for various environmental conditions, a reliable numerical simulation tool is essential. In this work, the current load on a cage is calculated using a Morison-force model applied at instantaneous positions of equivalent-net modeling. Variations of solidity ratio (Sn) of the net and current speed are considered. An equivalent array of cylinders is built to represent the physical netting. Based on the systematic comparisons between the published experimental data for Raschel nets and the current numerical simulations, carried out using the commercial software OrcaFlex, a new formulation for Cd values, used in the equivalent-net model, is presented. The similar approach can also be applied to other netting materials following the same procedure. In case of high solidity ratio and current speed, the hybrid model defines Cd as a function of Re (Reynolds number) and Sn to better represent the corresponding weak diffraction effects. Otherwise, the conventional Cd values depending only on Re can be used with including shielding effects for downstream elements. This new methodology significantly improves the agreement between numerical and experimental data.