Seaweed Growth Monitoring with a Low-Cost Vision-Based System.

In this paper, we introduce a method for automated seaweed growth monitoring by combining a low-cost RGB and stereo vision camera. While current vision-based seaweed growth monitoring techniques focus on laboratory measurements or above-ground seaweed, we investigate the feasibility of the underwater imaging of a vertical seaweed farm. We use deep learning-based image segmentation (DeeplabV3+) to determine the size of the seaweed in pixels from recorded RGB images. We convert this pixel size to meters squared by using the distance information from the stereo camera. We demonstrate the performance of our monitoring system using measurements in a seaweed farm in the River Scheldt estuary (in The Netherlands). Notwithstanding the poor visibility of the seaweed in the images, we are able to segment the seaweed with an intersection of the union (IoU) of 0.9, and we reach a repeatability of 6% and a precision of the seaweed size of 18%.

Continuous light (relative to a 12:12 photoperiod) has no effect on anxiety-like behaviour, boldness, and locomotion in coho salmon (Oncorhynchus kisutch) post-smolts in recirculating aquaculture systems at a salinity of either 2.5 or 10 ppt.

There is increased interest in rearing salmon in Recirculating Aquaculture Systems (RAS), where environmental conditions can be tightly controlled to optimize growth. Photoperiod and salinity are two important parameters that can be manipulated in RAS. A longer photoperiod permits more time for feeding, while intermediate salinities may reduce the energetic costs of ionoregulation, both of which may enhance growth. However, little is known about how rearing at different photoperiods and salinity affect behaviour, an understudied but important research topic for intensive fish rearing. To address this, we examined the behavioural effects of two salinities and two photoperiod regimes in coho salmon (Oncorhynchus kisutch) post-smolts reared continuously for 120 days in a RAS. Fish were reared on a photoperiod of either 12 h light:12 h dark (12:12), or 24 h light (24:0) at salinities of 2.5 and 10 ppt. To investigate behavioural differences associated with these treatments, we quantified: i) movement in an open-field test, ii) exploratory behaviour/boldness using a novel object approach test, and iii) anxiety-like behaviour with a light/dark test. The 24:0 groups displayed no differences in boldness/anxiety-like behaviour and locomotion relative to the 12:12 groups at their respective salinities. Taken together, fish reared under continuous light (24:0) show negligible behavioural alterations compared to fish reared under normal light dark conditions (12:12).

Effects on the survival rates, hematological parameters, and neurotransmitters in olive flounders, Paralichthys olivaceus, reared in bio-floc and seawater by Streptococcus iniae challenge.

Bacterial infections cause huge losses to aquaculture globally, and increased antibiotic resistance means that alternative methods of reducing mortality from bacterial diseases are required. We compared the resistance of Juvenile olive flounders, Paralichthys olivaceus, to Streptococcus iniae between those reared in biofloc and seawater conditions for ten months. Experimental fish were challenged with S. iniae at concentrations of 0, 3.36 × 106, 3.36 × 107, 3.36 × 108, and 3.36 × 109 colony forming units (CFU)/g fish for 96 h to evaluate the difference in S. iniae susceptibility of flounders reared in biofloc and seawater. The 96 h lethal concentration 50% (LC50) of fish injected with S. iniae was 2.41 × 109 CFU/g fish in biofloc and 1.51 × 108 CFU/g fish in seawater. Hematological parameters such as hemoglobin and hematocrit significantly decreased when fish were challenged by S. iniae. Plasma components such as calcium, glucose, cholesterol, total protein, GOT, GPT, and ALP were significantly altered by S. iniae infection and acetylcholinesterase activity was significantly inhibited. These results indicate that S. iniae infection affects the survival rates, hematological parameters, and neurotransmitter levels of flounders reared in biofloc and seawater, and that S. iniae susceptibility was higher in flounders reared in seawater than those reared in biofloc.

An automated aquatic rack system for rearing marine invertebrates.

BACKGROUND: One hundred years ago, marine organisms were the dominant systems for the study of developmental biology. The challenges in rearing these organisms outside of a marine setting ultimately contributed to a shift towards work on a smaller number of so-called model systems. Those animals are typically non-marine organisms with advantages afforded by short life cycles, high fecundity, and relative ease in laboratory culture. However, a full understanding of biodiversity, evolution, and anthropogenic effects on biological systems requires a broader survey of development in the animal kingdom. To this day, marine organisms remain relatively understudied, particularly the members of the Lophotrochozoa (Spiralia), which include well over one third of the metazoan phyla (such as the annelids, mollusks, flatworms) and exhibit a tremendous diversity of body plans and developmental modes. To facilitate studies of this group, we have previously described the development and culture of one lophotrochozoan representative, the slipper snail Crepidula atrasolea, which is easy to rear in recirculating marine aquaria. Lab-based culture and rearing of larger populations of animals remain a general challenge for many marine organisms, particularly for inland laboratories. RESULTS: Here, we describe the development of an automated marine aquatic rack system for the high-density culture of marine species, which is particularly well suited for rearing filter-feeding animals. Based on existing freshwater recirculating aquatic rack systems, our system is specific to the needs of marine organisms and incorporates robust filtration measures to eliminate wastes, reducing the need for regular water changes. In addition, this system incorporates sensors and associated equipment for automated assessment and adjustment of water quality. An automated feeding system permits precise delivery of liquid food (e.g., phytoplankton) throughout the day, mimicking real-life feeding conditions that contribute to increased growth rates and fecundity. CONCLUSION: This automated system makes laboratory culture of marine animals feasible for both large and small research groups, significantly reducing the time, labor, and overall costs needed to rear these organisms.

Heterogeneous Cubic Multidimensional Integrated Circuit for Water and Food Security in Fish Farming Ponds.

Among major food production sectors, world aquaculture shows the highest growth rate, providing more than 50% of the global seafood market. However, water pollution in fish farming ponds is regarded as the leading cause of fish death and financial losses in the market. Here, an Internet of Things system based on a cubic multidimensional integration of circuit (MD-IC) is demonstrated for water and food security applications in fish farming ponds. Both faces of the silicon substrate are used for thin-film-based device fabrication. The devices are interconnected via through-silicon-vias, resulting in a bifacial complementary metal-oxide-semiconductor-compatible electronics system. The demonstrated cubic MD-IC is a complete, small, and lightweight system that can be easily deployed by farmers with no need for specialists. The system integrates on its outer sides simultaneous air and water quality monitoring devices (temperature, electrical conductivity, ammonia, and pH sensors), solar cells for energy-harvesting, and antenna for real-time data-transfer, while data-management circuitry and a solid-state battery are integrated on its internal faces. Microfluidic cooling technology is used for thermal management in the MD-IC. Finally, a biofriendly polymeric encapsulation is used to waterproof the embedded electronics, improve the mechanical robustness, and allow the system to float on the surface of the water.

Effects of feeding level and C/N ratio on water quality, growth performance, immune and antioxidant status of Litopenaeus vannamei in zero -water exchange bioflocs-based outdoor soil culture ponds.

Two trials were conducted as follows: the first trial was a 90-day experiment to determine the effects of reducing feeding level on shrimp status; the second trial (90 days) is based on the first trial to explore the suitable C/N ratio of biological flocs for shrimp culture in outdoor soil ponds. Results showed that the BFV levels increased gradually and then tended to be stable in the treatment groups. Concentrations of TAN and NO2-N were maintained low level in each treatment pond during experimental period. The final body weight, biology body length and yield of the shrimp in each trial with no significantly different (P > 0.05) while food coefficient and THC of the shrimp in 70% feeding level and C/N12 treatment were slightly lower than in the 100% feeding level and C/N16 treatment respectively (p < 0.05). The antibacterial activity and bacteriolytic activity in C/N16 treatment group were higher than in C/N12 (p < 0.05), while there were no significant difference between the two feeding levels (70%,100%) (P > 0.05). The shrimp in 70% feeding level and C/N12 treatment had the higher T-AOC in both the plasma and the hepatopancreas when compared with 100% feeding level and C/N16 treatment group (p < 0.05). The SOD activity of plasma in 70% treatment group was higher than in 100% (p < 0.05), while it was no significant difference between the two C/N ratios (12,16) in both the plasma and the hepatopancreas (P > 0.05). The effects of two feeding levels and C/N ratios on the GSH level and the ratio of GSH/GSSG in the plasma and the hepatopancreas of shrimp showed no significant difference (P > 0.05). The results showed that 70% feeding level and C/N12 ratio could provide adequate nutrition for shrimp to maintain a normal physical health status with the presence of bioflocs.

Potential influence of jaggery-based biofloc technology at different C:N ratios on water quality, growth performance, innate immunity, immune-related genes expression profiles, and disease resistance against Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus).

Biofloc technology is increasingly becoming the most promising aquaculture tool especially in places where water is scarce and the land is very expensive. The dynamics of water quality, as well as plankton and microbial abundance, are collectively necessary for successful fish farming. The prospective use of jaggery as a potential carbon source and its influence on water quality, growth performance, innate immunity, serum bactericidal capacity, and disease resistance to Aeromonas hydrophila was investigated in Oreochromis niloticus. A completely randomized design was used in triplicates, where the control group was reared in a water system with no carbon source, while T1, T2, and T3 groups were raised in biofloc systems at C:N ratios of C:N12, C:N15, and C:N20, respectively. Water specimens were collected daily and fortnightly, while blood, serum, and head kidneys were collected at 75 days of experimental period for further analysis. TAN, nitrite, and ammonia values were considerably reduced, while the TSS values elevated significantly in all treated groups compared to the control. Jaggery-based biofloc system (JB-BFT) has a pronounced effect on hematological and growth performance parameters rather than control. Similarly, serum antioxidants, lysozyme, protease, antiprotease and bactericidal capacity were significantly increased (p < 0.05) in the treated groups in a dose-dependent manner. LYZ, TNF-α, and IL-1ß genes were upregulated in proportion to C:N ratios with the highest fold in C:N20. Furthermore, fish treated with JB-BFT presented lower cumulative mortalities and better relative levels of production (RLP) after experimental challenge with A. hydrophila compared to control. In conclusion, JB-BFT has a robust influence on Nile tilapia (O. niloticus) innate immunity through favorable innovation of various immune-cells and enzymes as well as upregulating the expression levels of immune-related genes. This study offers jaggery as a new carbon source with unique properties that satisfy all considerations of biofloc technology in an eco-friendly manner.

Water Treatment for Fish Aquaculture System by Biochar-Supplemented Planting Panel System.

Rice husk biochars were prepared by carbonization at 400-600°C. The products were analyzed by FTIR, SEM-EDS, BET, and approximate analysis in order to find final products with the best properties and the lowest carbonization temperature. It has been found that the biochar prepared at 500°C, which has 37.86 ± 0.11% yield, 341.0776 m2/g of BET surface area, and 0.136639 cm3/g of micropore volume, is suitable for use as a root supplement in the aquaponic system. The aquaponic systems consist of aquaculture and a hydroponic system with and without biochar supplement. The control experiment consists of an aquaculture and planting panel with biochar supplement disconnected from each other. Tilapia and Chinese morning glory were used for growth studies. The water quality from all aquaculture ponds has also been analyzed at an interval of 10 days for 47 days. The results showed that the growth rates of Tilapia and Chinese morning glory in the aquaponic system with biochar were clearly higher than in the control experiment, which is in accordance with the water quality in each aquaculture pond. However, the growth rates of Tilapia (23.5 g/body vs. 22.7 g/body) and morning glory (3.907 g/stem vs. 2.609 g/stem) in supplemented biochar system tend to be higher than the nonsupplemented biochar system. It has been shown that rice husk biochar can help in treating water in the aquaponic system by increasing the amount of dissolved oxygen in the aquaculture water and conversion of toxic compounds to those beneficial for plant growth.

Implementation and Evaluation of Open-Source Hardware to Monitor Water Quality in Precision Aquaculture.

Precision aquaculture is a new field that allows farmers to have better control over aquaculture processes, facilitating decision-making and improving efficiency. The implementation and evaluation of a low-cost water-quality monitoring system based on open-source hardware, which is easy to rebuild for scientific applications, is reported in this paper. The proposed system measures temperature, dissolved oxygen, and pH, taking records and sending information through a wireless protocol (ZigBee) to a graphical user interface which can display information numerically and graphically, as well as simultaneously storing the information in a database. These variables are very important for aquaculture, as they have a direct influence on critical culture parameters such as growth and survival. Although it is a low-cost system, it offers good quality data and demonstrates efficiency for its use in precision aquaculture.

Design of a Practical Underwater Sensor Network for Offshore Fish Farm Cages.

In this paper, we present the design of a practical underwater sensor network for offshore fish farm cages. An overview of the current structure of an offshore fish farm, applied sensor network solutions, and their weaknesses are given. A mixed wireless-wired approach is proposed to mitigate the problem of wire breakage in underwater wired sensor networks. The approach is based on the serial arrangement of identical sections with wired and wireless interconnections areas. Wireless section alleviates underwater maintenance operations when cages are damaged. The analytical model of the proposed solution is studied in terms of maximum power transfer efficiency and the general formulas of the current in their transmitting antennas and sensor nodes are provided. Subsequently, based on simulations, the effects of parasitic resistance across the network are evaluated. A practical underwater sensor network to reach the 30 m depth with sensor nodes distanced 6 m is used to determine the proposal compliance with the ISO 11784/11785 HDX standard in its normal operation. Taking into account the cable breakage scenario, the results from experiments demonstrate the robustness of the proposed approach to keep running the sensor nodes that are located before the short circuit. Sensor node run time is reduced only 4.07% at most using standard values when a cable breakage occurs at the second deepest section.

Antiparasitic Effect of Copper Alloy Surface on Cryptocaryon irritans in Aquaculture of Larimichthys crocea.

Copper and alloys containing >60% copper by weight are antimicrobial. In aquaculture, copper alloys are used as part of corrosion-resistant cages or as part of copper coating. To test whether a copper alloy surface prevents the outbreak of parasitosis in the aquaculture of Larimichthys crocea, we covered the bottom of the aquaculture tank with sheets of copper alloy containing 74% to 78% copper, and we cultured L. crocea juveniles that had been artificially infected with the protozoan parasite Cryptocaryon irritans Our results showed that these copper alloy sheets effectively blocked the infectious cycle of C. irritans within a 1-week period and significantly reduced the number of C. irritans trophonts and tomonts, thereby decreasing the mortality rate of L. crocea In in vitro assays, the cytoplasmic membranes of protomonts disintegrated and the cytoplasm overflowed after just 5 minutes of contact with copper alloy surfaces. Although the same cytoplasmic membrane disintegration was not observed in tomonts, the tomonts completely lost their capacity for proliferation and eventually died following direct contact with copper alloy sheets for 1 h; this is likely because C. irritans tomonts took in >100 times more copper ions following contact with the copper alloy sheets than within the control aquaculture environment. Exposure to copper alloy sheets did not lead to excessive heavy metal levels in the aquacultured fish or in the culture seawater.IMPORTANCECryptocaryon irritans, a parasitic ciliate that penetrates the epithelium of the gills, skin, and fins of marine fish, causes acute suffocation and death in cultured fish within days of infection. Much of the existing research centers around the prevention of C. irritans infection, but no cure has been found. Studies demonstrate that copper has strong antimicrobial properties, and fish grown in copper-containing cages have lower rates of C. irritans infection, compared to those grown in other currently used aquaculture cages. In this study, we found that an alloy containing 74% to 78% copper by weight effectively killed C. irritans cells and prevented cryptocaryoniasis outbreaks within a 1-week period. These findings offer a new perspective on the prevention and control of cryptocaryoniasis.

Effects of water recirculation rate on the microbial community and water quality in relation to the growth and survival of white shrimp (Litopenaeus vannamei).

BACKGROUND: Microbial community and its management are crucial to the stabilization of culture environment for recirculating aquaculture system (RAS). Although several studies have been carried out for the microbial community of RAS, few studies were on the RAS for shrimp. Water recirculation ratio is an important factor for the microbial community and the management of RAS. Therefore, low (LC), medium (MC) and high (HC) recirculation ratio systems were set to explore the microbial community constitution of RAS for Litopenaeus vannamei and study the effect of water recirculation rate on it. RESULTS: The bacterial community of bioreactor was mainly dominated by Proteobacteria (41.6-70.7%), followed with Planctomycetes (12.5-31.0%), Bacteroidetes (10.5-26.0%), Actinobacteria (1.1-4.8%) and Verrucomicrobia (1.4-6.8%) phylum. The most dominant family of bioreactor was Rhodobacteraceae or Planctomycetaceae. The bacterial community of culture water was simpler than bioreactor and dominated by Proteobacteria (61.8-96.4%). The dominant bacterial groups of bioreactor and culture water are also different among the three water recirculation rates, and the proportions of dominant groups showed a trend with the variety of water recirculation rate. Water quality indexes including ammonia and nitrite decreased with the increasing of water recirculation rate. According to the growth performance of L. vannamei, shrimp had better performance of growth rate and final weight in MC and HC, however, shrimp had higher survival and yield in LC. Shrimp survival and yield had an inverse correlation with water recirculation rate. CONCLUSIONS: The results demonstrate the microbial community of RAS for shrimp, highlight the importance of further studies on the function of bacterial taxa, and promote the understanding of the effects of water recirculation rate on the microbiota. The findings suggest that water recirculation rate has important impacts on the microbial community, water quality and shrimp growth. Increasing the water recirculation rate could improve the water quality and promote the growth of shrimp. However, the survival rate and yield of L. vannamei are higher under low water recirculation rate. Recirculation rate is an effective method to manage RAS, and its impact on RAS needs further study, especially in the application of low level of water recirculation.

The effect of rearing structures on behaviour and movement of juvenile steelhead Oncorhynchus mykiss.

The relative movement of juvenile steelhead Oncorhynchus mykiss reared on two treatments was investigated to provide insight on the effect of structure in the rearing environment on the behaviour of the fish before potential release into a natural river system. The progeny of wild broodstock were reared either in the presence or absence of structure in the tank environment for 7 months at the Oregon Hatchery Research Center located in Oregon, U.S.A. Behavioural assessments, including movement response to a simulated predator, showed that fish reared on structure moved a similar amount (based on line crosses) as fish reared in bare hatchery tanks. No significant difference was observed in the proportion of time spent near a small structure within the behavioural test tank between the two treatments, but all fish showed decreased movement over time with each subsequent predation event. Fish from both treatments spent 30% of their time in the section of the tank containing the structure, which was one section out of a total of eight sections. In both treatments, fish foraged 20% of the time in the 2 min following the introduction of live tubifex prey (two separate events). Overall, similar movement and foraging responses occurred following mock predation events for juveniles reared either with or without structure. Developing assessment tools such as these, that measures behaviours related to survival based on rearing environment should allow managers to better predict the survival and effect of rearing conditions on the release of hatchery-origin fish into the wild.

The effect of substrate rearing on growth, aerobic scope and physiology of larval white sturgeon Acipenser transmontanus.

The effect of substratum on growth and metabolic rate was assessed in larval white sturgeon Acipenser transmontanus. Yolk-sac larvae (YSL) were reared in bare tanks or tanks with gravel as substratum from hatch until approximately 16 days post hatch (dph). The effect of an artificial substratum was also evaluated on growth alone. Substratum had a significant effect on mass, with larvae reared in gravel and artificial substrata being larger than those reared without substratum. Routine metabolic rates were significantly lower and relative aerobic scope (the difference between maximum and routine metabolic rate) was significantly higher for YSL and feeding larvae (FL) reared in gravel relative to those reared in bare tanks, particularly before fish started feeding exogenously. Furthermore, gravel-reared larvae had higher whole-body glycogen concentrations relative to bare-tank-reared larvae. Routine factorial scope (maximum metabolic rate divided by routine metabolic rate) was relatively low in all treatments (< 1·7) indicating a limited ability to elevate metabolic rate above routine early in development and mass exponents for metabolic rate exceeded 1. Taken together, these data indicate that YSL reared without substratum may divert more of their energy to non-growth related processes impairing growth. This finding underscores the importance of adequate rearing substratum for growth of A. transmontanus and may provide support for habitat restoration and alternative hatchery rearing methods associated with sturgeon conservation.

Comparison between Atlantic salmon Salmo salar post-smolts reared in open sea cages and in the Preline raceway semi-closed containment aquaculture system.

The use of closed containment (CCS) or semi-closed containment systems (S-CCS) for Atlantic salmon Salmo salar aquaculture is under evaluation in Norway. One such system is the Preline S-CCS, a floating raceway system that pumps water from 35 m depth creating a constant current through the system. Exposing fish to moderate water currents is considered aerobic exercise and it is often perceived as positive for fish welfare, growth, food utilization, muscle development and cardiac health. The present study compared fish reared in the Preline S-CCS and in a reference open pen. Samples were taken in fresh water before being transferred to the seawater systems and after 1, 2 and 4 months in seawater and analysed for growth, mortality, muscle development and plasma insulin-like growth factor I (IGF-I) levels. Moreover, gene transcription were determined in the skeletal muscle [igf-I, insulin-like growth factor 1 receptor a (igf1ra) and insulin-like growth factor 1 binding protein 1a (igf1bp1a)] and cardiac transcription factors [myocyte-specific enhancer factor 2C (mef2c), gata4 and vascular endothelial growth factor (vegf)]. While the results suggest that post-smolts in Preline S-CCS were smaller than reference fish, fish from Preline S-CCS have less accumulated mortality at the end of the experiment and showed 2.44 times more small muscle fibres than the reference group fish after 4 months in seawater. These results confirmed what was previously observed in the second generation of Preline. Similar levels of big muscle fibres between Preline S-CCS and reference suggest a similar hypertrophy of muscle fibres even with lower IGF-I expression in the Preline S-CCS. Cardiac gene transcription suggests cardiac hypertrophy was observed after 4 months in seawater in the Preline S-CCS group. Altogether, Preline S-CCS is a promising technology able to produce more robust S. salar with a faster growth and lower mortality in the subsequent standard open cage system growth period.

The application of ceramsite ecological floating bed in aquaculture: its effects on water quality, phytoplankton, bacteria and fish production.

In recent years, biological floating bed technology has been applied increasingly in aquaculture ponds. In this study we developed a novel floating bed made from ceramsite and studied its effect on water quality, phytoplankton, bacteria and fish growth. Water quality was effectively regulated and controlled in ceramsite floating bed (CFB) ponds with an average transparency of 23.18 cm, ammonia nitrogen (NH4+-N) of 2.30 mg L-1, total nitrogen (TN) of 5.09 mg L-1 and total phosphate (TP) of 1.32 mg L-1 which are lower than in control ponds without CFB. Increased phytoplankton species diversity, bacterial number, metabolic activity and microbial diversity was observed with CFB. At the end of growth stage, feed conversion ratio (FCR) was reduced with a total fish yield of 14,838 kg ha-1 at a survival rate of 77.2% in CFB ponds, which is significantly higher than control (P < 0.05). These results emphasize the potential of ecological floating bed to improve water quality, microalgal diversity, reduce the risk of harmful algal blooms and increase the number, activity and diversity of microorganisms as well as fish yield.

A Description of a Noninvasive Surgical Training Pathway Using Translational Tools to Teach Intracoelomic Implantation of Acoustic Transmitters in Fish.

Researchers engaged in surgical implantation of acoustic transmitters into fish must receive adequate and appropriate training to ensure the welfare of their subjects and the quality of the data collected. Increasingly, researchers are being encouraged to partner with veterinarians to improve training and to consider the principles of animal welfare in training. Here, we describe a five-stage training pathway, including implementation of new training tools (the Translational Training Tools and field certification), that was developed collaboratively by researchers and veterinarians and addresses the "three Rs" of animal welfare in the context of surgical training. The three Rs include animal replacement, reduction of the number of animals used, and refinement of techniques to decrease or eliminate pain or distress. The Translational Training Tools, described in the context of the training pathway, use tools as replacement models during training to reduce the number of animals used and allow for refinement of surgical skills prior to working on live animals. The purpose of this paper is to document the Translational Training Tools and the training pathway, which will be useful in developing de novo protocols for review by Institutional Animal Care and Use Committees and similar bodies.

A new reactor for denitrification and micro-particle removal in recirculated aquaculture systems.

A 'membrane-denitrification' reactor (MDR) was developed and tested in a semi-technical recirculation aquaculture system in comparison to a double - without MDR - as reference system. The MDR consisted of a reactor with an ultrafiltration membrane unit for removal of micro-particles (e.g. sludge flocs, bacteria and parasites). Specific carrier material provided surfaces for biofilm growth in a fluidized bed reactor with ethanol as carbon source for denitrification. The continuous motion of these carriers cleaned the membrane surface. With online and laboratory measurements of water parameters and operational data the feasibility of the concept was verified. An advantage is that no chemicals are needed to clean the membranes. Examinations of the fish and water analyses proved an MDR can positively influence cortisol, as a stress marker, and the microflora of the aquatic system.

High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium.

Nannochloropsis salina was grown on a mixture of standard growth media and pre-gasified industrial process water representing effluent from a local biogas plant. The study aimed to investigate the effects of enriched growth media and cultivation time on nutritional composition of Nannochloropsis salina biomass, with a focus on eicosapentaenoic acid (EPA). Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scale using a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large-scale cultivation of Nannochloropsis salina at these conditions could improve the nutritional properties such as EPA, tocopherol, protein and carotenoids compared to laboratory-scale cultivated microalgae. EPA reached 44.2% ± 2.30% of total fatty acids, and α-tocopherol reached 431 ± 28 µg/g of biomass dry weight after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark. The resulting biomass is a rich source of EPA and also a good source of protein (amino acids), tocopherols and carotenoids for potential use in aquaculture feed industry.

Eco-friendly porous concrete using bottom ash aggregate for marine ranch application.

This article presents the test results of an investigation carried out on the reuse of coal bottom ash aggregate as a substitute material for coarse aggregate in porous concrete production for marine ranch applications. The experimental parameters were the rate of bottom ash aggregate substitution (30%, 50% and 100%) and the target void ratio (15%, 20% and 25%). The cement-coated granular fertiliser was substituted into a bottom ash aggregate concrete mixture to improve marine ranch applications. The results of leaching tests revealed that the bottom ash aggregate has only a negligible amount of the ten deleterious substances specified in the Ministry of Environment - Enforcement Regulation of the Waste Management Act of Republic Korea. The large amount of bubbles/air gaps in the bottom ash aggregate increased the voids of the concrete mixtures in all target void ratios, and decreased the compressive strength of the porous concrete mixture; however, the mixture substituted with 30% and 10% of bottom ash aggregate and granular fertiliser, respectively, showed an equal strength to the control mixture. The sea water resistibility of the bottom ash aggregate substituted mixture was relatively equal to that of the control mixture, and also showed a great deal of improvement in the degree of marine organism adhesion compared with the control mixture. No fatality of fish was observed in the fish toxicity test, which suggested that bottom ash aggregate was a harmless material and that the combination of bottom ash aggregate and granular fertiliser with substitution rates of 30% and 10%, respectively, can be effectively used in porous concrete production for marine ranch application.