Field Of Aquaculture Research Articles

What governs the success of aquaculture field schools - Insights from Odisha and Chattisgarh

ICAR-CIFA piloted four Aquaculture Field Schools (AFS), a model of the farmer to farmer extension, of which three are in Odisha and one in Chhattisgarh. The AFSs are attracting farmers and stakeholders as they provide a platform to share experience and cross-learning. In this research, an attempt has been made to identify the factors that contribute to the successful performance of AFS. Data were collected from 166 user farmers selected randomly from the list available with operators. Five variables viz., age of fish farmer, frequency of visit to AFS, duration of visit, interaction with the fellow farmers, advocation of advanced technologies of ICAR-CIFA to other farmers were observed to be significantly contributing to yield of fish. The multiple correlation coefficient indicated that there was a significant and positive correlation between the observed and predicted value of fish yield (p<0.05).Key words Aquaculture Field schools; Fish farmer; Factors

A novel jumbo Tenacibaculum maritimum lytic phage with head-fiber-like appendages.

A novel jumbo bacteriophage (myovirus) is described. The lytic phage of Tenacibaculum maritimum, which is the etiological agent of tenacibaculosis in a variety of farmed marine fish worldwide, was plaque-isolated from seawater around a fish aquaculture field in Japan. The phage had an isometric head 110-120 nm in diameter, from which several 50- to 100-nm-long flexible fiber-like appendages emanate, and a 150-nm-long rigid contractile tail. The full genomes of the two representative phages (PTm1 and PTm5) were 224,680 and 226,876 bp long, respectively, both with 29.7% GC content, and the number of predicted open reading frames (ORFs) was 308 and 306, respectively. The average nucleotide sequence identity between PTm1 and PTm5 was 99.95%, indicating they are quite similar to each other. A genetic relationship was found in 15.0-16.6% of the predicted ORFs among the T. maritimum phages PTm1 and PTm5, the Tenacibaculum spp. phage pT24, and the Sphingomonas paucimobilis phage PAU. Phylogenetic analysis based on the terminase large subunit genes revealed that these four phages (PTm1, PTm5, pT24 and PAU) are more closely related than the other 10 jumbo myoviruses that have similar genome sizes. Transmission electron microscopy observations suggest that the head fibers of the T. maritimum phage function as tentacles to search and recognize the host cell surface to facilitate infection.

Aquaculture and by-products: Challenges and opportunities in the use of alternative protein sources and bioactive compounds.

There is a growing concern about chronic diseases such as obesity, diabetes, hypertension, hypercholesterolemia, cancer and cardiovascular diseases resulting from profound changes in the western lifestyle. Aquaculture by-products are generated in large quantities and they can be profitably recycled through their bioactive compounds used for health or food supplements. Improving waste utilization in the field of aquaculture is essential for a sustainable industry to prevent or minimize the environmental impact. In this sense fish by-products are a great source of protein and omega-3 polyunsaturated fatty acids which are particularly studied on Atlantic salmon or rainbow trout. Fish protein hydrolysate (FPH) obtained from chemical, enzymatical and microbial hydrolysis of processing by-products are being used as a source of amino acids and peptides with high digestibility, fast absorption and important biological activities. Omega-3 polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) from fish discards have been reported to decrease postprandial triacylglycerol levels, reduction of blood pressure, platelet aggregation and the inflammatory response. Crustacean by-products can also be used to produce chitosan with antioxidant and antimicrobial activity for food and pharmaceutical industries and carotenoids with important biological activity. Seaweeds are rich in bioactive compounds such as alginate, carrageenan, agar, carotenoids and polyphenols with different biological activities such as antioxidant, anticancer, antidiabetic, antimicrobial or anti-inflammatory activity. Finally, regarding harvest microalgae, during the past decades, they were mainly used in the healthy food market, with >75% of the annual microalgal biomass production, used for the manufacture of powders, tablets, capsules or pills. We will report and discuss the present and future role of aquaculture by-products as sources of biomolecules for the design and development of functional foods/beverages. This chapter will focus on the main bioactive compounds from aquaculture by-products as functional compounds in food and their applications in biomedicine for the prevention and treatment of diseases.

Growth trajectory analysis of Pacific whiteleg shrimp ( Litopenaeus vannamei ): Comparison of the specific growth rate, the thermal‐unit growth coefficient and its adaptations

Empirical growth models have widespread application in the field of aquaculture. These models allow estimates of harvest size and waste outputs in addition to nutrient and feed requirements. In an effort to increase the ability to predict shrimp growth, the specific growth rate (SGR) and thermal-unit growth coefficient (TGC) models were fitted to 15 datasets encompassing growth of Pacific whiteleg shrimp (Litopenaeus vannamei). Shrimp were reared under commercial conditions in Southeast Asia with weights ranging from 0.01 g to 34 g. Growth rates were regressed against body weights to identify changes in growth pattern across life stages. Analysis identified two distinct patterns of growth, with a break point between stanzas at 7.5 g. The body weight exponent of the TGC model, traditionally assumed to be (1 − b) = 1/3, was solved for iteratively in each identified growth stanza in an effort to improve the goodness of fit of the TGC model. Average body weight exponents in the first and second stanzas were 0.416 and 0.952 respectively. Projected growth trajectories using these exponents resulted in significantly better fits in comparison to the traditional TGC and the SGR on the basis of statistical measures of goodness of fit.

Intermediary metabolic response and gene transcription modulation on the Sub-Antarctic notothenioid Eleginops maclovinus (Valenciennes, 1930) injected with two strains of Piscirickettsia salmonis.

Pathogen interactions with cultured fish populations are well studied, but their effects on native fishes have not been characterized. In Chile, the disease caused by bacterial species Piscirickettsia salmonis represents one of the main issues and is considered to be one of the important pathogens in the field of aquaculture. They have been found to infect native fish. Therefore, it is necessary to understand the impact of P.salmonis on native species of local commercial value, as well as the potential impact associated with the emergence of antibiotic-resistant strains of P.salmonis. Due to this purpose, the native fish Eleginops maclovinus was used in our study. Fish were randomly distributed in tanks and intraperitoneally inoculated with two strains of P.salmonis. No mortality was recorded during the experiment. Cortisol, glucose and total α-amino acid levels increased in fish injected with AUSTRAL-005 strain compared to sham-injected and LF-89-inoculated fish. Moreover, results showed an increase in the activity of carbohydrates and lipids metabolism in liver; and an increase in the carbohydrates, lipids and total α-amino acid metabolism in muscle after injection with AUSTRAL-005. Our results suggest that P.salmonis modulates the physiology of E.maclovinus and the physiological impact increase in the presence of the antibiotic-resistant strain AUSTRAL-005.

Bio-electrosprayed human sperm remain viable

The research article demonstrates the ability for bio-electrosprays to directly handle human sperm without damaging them in anyway. Thus, elucidating the significant implications this platform biotechnology has to the human reproductive sciences and medicine fields, which also extend to the agriculture and aquaculture fields of research and development. In our previous investigations, we demonstrated that certain living cells exposed to bio-electrosprays remained viable, and behaved as expected in comparison to control cells. These studies also extended to post-bio-electrosprayed cells being transplanted into mice, which demonstrated no rejection, and in fact they were seen to integrate with the surrounding host tissues. Therefore, highlighting bio-electrosprays as a front running bioplatform for engineering functional tissues for repair, replacement and rejuvenation of damaged and/ageing tissues. In the present studies, we take bio-electrosprays further into human health, investigating the possibility of this platform biotechnology to directly handle the smallest and most highly specialized cell in the human body, the spermatozoon. These studies demonstrated the ability for bio-electrosprays to directly handle human sperm without compromising their viability, while also demonstrating the technology’s capacity to encapsulate human sperm. These investigations reported herein present interesting implications to human reproductive science and medicine, while also having promising applicability to areas such as the agriculture and aquaculture industries.

Land cover mapping of the Mekong Delta to support natural resource management with multi-temporal Sentinel-1A synthetic aperture radar imagery

Synthetic aperture radar (SAR) has great potential for land cover mapping, especially in tropical regions, where frequent cloud cover obstructs optical remote sensing. The aim of this study is to demonstrate the utility of Sentinel-1A SAR imagery for characterising land use and land cover (LULC) in Bac Lieu, a rapidly developing province of the Mekong Delta, Vietnam, to support natural resource management for land use planning and monitoring. Twenty-one SAR images acquired in 2016 were classified in a four-step process. Firstly, the SAR images were pre-processed to produce Grey Level Co-occurrence Matrix (GLCM) texture images. Then, to reduce the effects of rainfall variation confounding the classification, the images were divided into two categories: dry season (Jan–April) and wet season (May–December) and three input image sets were produced: 1) a single-date composite image (two VV-VH bands), 2) a multi-temporal composite image (eight bands for dry season and sixteen bands for wet season) and 3) a multi-temporal and textural composite image (sixteen bands for dry season and thirty two bands for wet season). We then applied Support Vector Machines (SVM) and Random Forest (RF) classifiers to characterise urban, forest, aquaculture, and rice paddy field for the three input image sets. We tested a combination of input images and classification algorithms and found that no matter the classification algorithms used, multi-temporal images had a higher overall classification accuracy than single-date images and that differences between classification algorithms were minimal. The most accurate classification resulted from a combination of the SVM classifier and multi-temporal and textural input image sets from the dry and wet seasons; with an overall accuracy of 94.81% and Kappa coefficient of 0.92. Our land cover mapping showed that Bac Lieu province is dominated by shrimp farming and rice paddy fields, with natural coastal forested ecosystems only made up a small proportion of the province. The results demonstrated the potential use of SAR as an up-to-date complementary data source of land cover information for local authorities, to support their land use master plan and to monitor illegal land use changes. Long-term monitoring of land use in Bac Lieu province, as well as in the Mekong Delta, will be crucial for decision makers, to ensure sustainability and food security in this region.

USE of group sequential test methods in the survival analysis in aquaculture

The information obtained as a result of research in natural sciences should have a high statistical power, that is also valid for the field of aquaculture. The sample size needs to be increased in order to increase the statistical power of a scientific study. However, studying on large sample size may not always be possible. Therefore, many experimental designs have been developed for data collection purposes to keep the sample size minimum. Group sequential designs have been enhanced for the data entered sequentially to the trial most of the time in medicine, production, economy etc. With these designs, the studies can be early terminated and results can also be obtained the results based on with high statistical power with smaller sample size. These experimental designs are specifically applied to survival data. In the survival analysis used in the field of aquaculture, all of the samples are included at the beginning. One of the important risk in this method is the loss of most or all of the samples due to unexpected effects. If this occurs, the trial must be discontinued or repeated and procedure then becomes time consuming and expensive. To minimize these risks the use of group sequential test methods is proposed in our study. It can be done by a standard treatment (or survival etc.) group and a (or more) new treatment (or survival etc.) group(s). For this approach, 450 rainbow trout were divided into three sequential groups including 1. Control, 2. Aeromonas hyrophilia infected group and 3. Yersinia ruckeri infected group. The survival-time of each sequential run was evaluated by means of four interim analyses via a retrospective trial design. By entering new samples during the trial, both unexpected risks were minimized and continuous data was provided. After the third interim analysis, it was determined that the survival times of the three groups were significantly different from each other and the early termination of the trial was approved.

Review of Dissolved Oxygen Detection Technology: From Laboratory Analysis to Online Intelligent Detection.

Dissolved oxygen is an important index to evaluate water quality, and its concentration is of great significance in industrial production, environmental monitoring, aquaculture, food production, and other fields. As its change is a continuous dynamic process, the dissolved oxygen concentration needs to be accurately measured in real time. In this paper, the principles, main applications, advantages, and disadvantages of iodometric titration, electrochemical detection, and optical detection, which are commonly used dissolved oxygen detection methods, are systematically analyzed and summarized. The detection mechanisms and materials of electrochemical and optical detection methods are examined and reviewed. Because external environmental factors readily cause interferences in dissolved oxygen detection, the traditional detection methods cannot adequately meet the accuracy, real-time, stability, and other measurement requirements; thus, it is urgent to use intelligent methods to make up for these deficiencies. This paper studies the application of intelligent technology in intelligent signal transfer processing, digital signal processing, and the real-time dynamic adaptive compensation and correction of dissolved oxygen sensors. The combined application of optical detection technology, new fluorescence-sensitive materials, and intelligent technology is the focus of future research on dissolved oxygen sensors.

Optimasi Pembentukan Bioflok Dari Skeletonema sp., Nitzschia sp. Dan Bakteri Probiotik Melalui Variasi pH Secara In Vitro

Abstract. Bioflok is a microbial community consisting of bacteria, protozoa and zooplankton, as a shrimp feed supplement containing amino acids methionin, vitamins, minerals and enzymes that can help the process of digestion of feed on shrimp. Bioflux is a suspension contained in water consisting of microalgae, and bacteria that are potentially developed in the field of aquaculture that is as natural food because of high protein content as well as an alternative solution to the problem of cultivation waste. This study aims to find out how optimization of biofloc formation from Skeletonema sp., Nitzschia sp. and probiotic bacteria through the optimum salinity level used on the Walne medium. This research was conducted at Biology Laboratory of Makassar State University. This research was an experimental research using Completely Randomized Design (RAL) consisting of 5 treatments and 3 replications, ie treatment with pH 9, treatment with pH 8,5, treatment with pH 8, treatment with pH 7,5, treatment with pH 7 , pH 6.5 treatment, pH 6 treatment, and pH 5 treatment, on Walne medium using a combination of inoculant Skeletonema sp., Nitzschia sp. and probiotic bacteria. Parameters observed were biomass (dry weight) floc, floc volume, floc activity, temperature, pH, light intensity, and aeration rate. Data were analyzed using Analysis of Variance (ANOVA) and continued by Duncan test (α 0,05). The results showed that the treatment with pH 6.5 was the optimum salinity for biofloc formation shown by the highest floc biomass, the highest floc volume, and the highest floc activity with the floc volume indicator 0.01278 ml, dry weight (biomass) 0.00733 g / ml and floc activity 83.45 ml.Keywords: biofloc, ph, skeletonema sp., nitzschia sp., probiotic bacteria.

Impact of management practices and managerial ability on the financial performance of aquaculture farms in Bangladesh

Theoretical and empirical research on farm management suggests that management practices and managerial ability affect farms’ financial performance. However, the explicit application of these concepts is scarce within the aquaculture field. In this study, the impact of management practices and managerial ability on the financial performance of aquaculture farms are investigated in Bangladesh. The aquaculture sector in Bangladesh mainly comprises small extensive freshwater pond farms, a good representative of aquaculture production in developing countries. The results indicate that both management practices and managerial ability affect farm financial performance. These findings emphasize that small-scale extensive aquaculture can be made more economically sustainable in developing countries if knowledge on improving management practices and managerial abilities are disseminated to farmers and policymakers.

Phenotypic and molecular detection of Aeromonads infection in farmed Nile tilapia in Southern highland and Northern Tanzania

Aeromonads disease outbreaks are now becoming a common phenomenon in freshwater farmed fish worldwide. In Tanzania, the aquaculture field is increasingly growing save to sustain food protein demand and strengthen household income. To avoid losses that tilapia fish farmers might account, information on magnitude of infection and characteristics of the aetiological agent is vital. This study aimed to establish the prevalence of aeromonads infection in farmed tilapia and assess pond and fish health management practices. A cross sectional study was carried out between February 2017 and October 2018 and a total of 816 whole fish samples were aseptically collected from 32 ponds in Ruvuma, Mbeya, Iringa and Kilimanjaro regions. During sampling, water quality parameters were taken and questionnaires to assess the knowledge of farmers were also provided. Isolation and identification of bacteria was conducted using conventional biotyping and molecular techniques. A total of 201 (80.4%) of 250 isolates that were conventionally identified were confirmed to be aeromonads by amplification of 820 bp rpoD gene, making the overall prevalence of 24.6% (201, n = 816). Sequencing of rpoD gene and phylogenetic analysis revealed two aeromonads species, Aeromonas hydrophila and Aeromonas veronii. To the best of our knowledge this is the first report to establish the prevalence of aeromonads in apparently healthy farmed tilapia in Southern highlands and Northern zone of Tanzania. In addition it was observed that farmers were lacking proper knowledge and awareness on pond management practices and fish health management. In conclusion, the infection rate of aeromonads in apparently health tilapia coupled with lack of proper knowledge and awareness on pond and fish health management by fish farmers in the study area poses risk of diseases outbreaks in their farms in future. Therefore, it is recommended that the farmers should be trained on basic pond and fish health management and control strategies.

URIC ACID LEVELS IN GESTATIONAL HYPERTENSIVE DISORDERS AND FETAL GROWTH RESTRICTION

The genus Golenkinia has not been studied for the production of metabolites of commercial interest. In this work, the accumulation and composition of oils and carotenoids was studied in a new isolated strain of the green alga Golenkinia sp. under salinity stress. Both the molecular and morphological characterization of the strain allowed us to identify it tentatively as G. brevispicula. As part of our morphological descriptions, we show previously unreported cellular stages. One of the most remarkable findings relates to the unprecedented observation of a reddish aplanospore stage in a Golenkinia strain resistant to desiccation. Salinity stress induced an increase in total lipids, reaching 37.2% of DW, and an increase in total carotenoids at the end of stress phase. According to the high lipid values with an equilibrated proportion of polyunsaturated fatty acids and the content of carotenoids dissolved in oil droplets, the lipids of this strain could have a potential application in the nutraceutical and aquaculture feed fields. Further studies are being conducted to optimize the growth and stress conditions in order to enhance biomass, oil and carotenoid productivity.

Effects of Marichromatium gracile YL28 on the nitrogen management in the aquaculture pond water

Nitrogen pollution in aquaculture needs the efficient and cost-effective in-situ technology. This study aims to apply Marichromatium gracile YL28 to in-situ bioremediation and test its ability to maintain the nitrogen balance in aquaculture. In laboratory aquaculture system, approximately 99.96% of nitrite (1 mg/L) was removed within 7 d through denitrification coupled with assimilatory nitrate reduction. Ammonium (3.5 mg/L) of 95.6% was directly assimilated by YL28 within 7 d. Moreover, in zero exchange water from shrimp (Penaeus vannamei) aquaculture field trials (20 days), YL28 significantly reduced the ammonium accumulation (0.6 mg/L) and 99.3% of nitrite (1.25 mg/L). Toxicological studies with the Institute of Cancer Research (ICR) mice and Oryzias melastigma indicated that M. gracile YL28 can be safely applied in aquatic ecosystems. All results demonstrate that strain YL28 has high promise for future applications of removing inorganic nitrogen and maintaining the nitrogen balance from in-situ aquaculture.

Synthesis and antiviral activity of a new arctigenin derivative against IHNV in vitro and in vivo

Viral diseases in aquaculture were challenging because there are few preventative measures and/or treatments. Our previous study indicated that imidazole arctigenin derivatives possessed antiviral activities against infectious hematopoietic necrosis virus (IHNV). Based on the structure-activity relationship in that study, a new imidazole arctigenin derivative, 4-(8-(2-ethylimidazole)octyloxy)-arctigenin (EOA), was designed, synthesized and its anti-IHNV activity was evaluated. By comparing inhibitory concentration at half-maximal activity (IC50), we found that EOA (IC50 = 0.56 mg/L) possessed a higher antiviral activity than those imidazole arctigenin derivatives in our previous study. Besides, EOA could significantly decrease cytopathic effect (CPE) and viral titer induced by IHNV in epithelioma papulosum cyprinid (EPC) cells. In addition, EOA significantly inhibited apoptosis induced by IHNV in EPC cells. Further data verified that EOA inhibited IHNV replication in rainbow trout, with reducing 32.0% mortality of IHNV-infected fish. The results suggested that EOA was more stable with a prolonged inhibitory half-life in the early stage of virus infection (1–4 days). Consistent with above results, EOA repressed IHNV glycoprotein gene expression in virus sensitive tissues (kidney and spleen) in the early stage of virus infection. Moreover, histopathological evaluation showed that tissues from the spleen and kidney of fish infected with IHNV exhibited pathological changes. But there were no lesions in any of the tissues from the control group and EOA-treaten group. In accordance with the histopathological assay, EOA could elicited anti-inflammation response in non-viral infected rainbow trout by down-regulating the expression of cytokine genes (IL-8, IL-12p40, and TNF-α). Altogether, EOA was expected to be a therapeutic agent against IHNV infection in the field of aquaculture.

Fish Species Diversity of Fars, by Esmaeili H.R & Teimori A. 2016. 288 p. Fars Environment Department, ISBN: 978-600-04-5600-9

Fars Province, as one of the largest provinces in Iran, has a significant fresh water fish diversity. The present work aimed to review the book entitled “Fish Species Diversity of Fars”, published by Fars Environmental Protection Agency in 2016. In this book, a list of fish species has been described from Fars Province. It provides important information on the taxonomy, morphological, biological, and ecological characteristics and conservation status of fish species. Hence, considering the rich content of this book, it is suggested for ichthyologist and others researches and students in fields of aquaculture, fisheries and biology.

Satellitome landscape analysis of Megaleporinus macrocephalus (Teleostei, Anostomidae) reveals intense accumulation of satellite sequences on the heteromorphic sex chromosome

The accumulation of repetitive DNA sequences on the sex-limited W or Y chromosomes is a well-known process that is likely triggered by the suppression of recombination between the sex chromosomes, which leads to major differences in their sizes and genetic content. Here, we report an analysis conducted on the satellitome of Megaleporinus macrocephalus that focuses specifically on the satDNAs that have been shown to have higher abundances in females and are putatively located on the W chromosome in this species. We characterized 164 satellite families in M. macrocephalus, which is, by far, the most satellite-rich species discovered to date. Subsequently, we mapped 30 satellites, 22 of which were located on the W chromosome, and 14 were shown to exist only on the W chromosome. Finally, we report two simple, quick and reliable methods that can be used for sex identification in M. macrocephalus individuals using fin clips or scales, which could be applicable to future studies conducted in the field of aquaculture.

Growth performance and blood profiles of striped catfish (Pangasianodon hypophthalmus) fed leaves extract of Myrmecodia tuberosa

Abstract. Nugroho RA, Hardi EH, Sari YP, Aryani R, Rudianto. 2019. Growth performance and blood profiles of striped catfish (Pangasianodon hypophthalmus) fed leaves extract of Myrmecodia tuberosa. Nusantara Bioscience 11: 89-96. The application of plant extract in the aquaculture field is gaining momentum. This study aimed to determine the effects of M. tuberosa Jack leaves extract on the growth performance and blood profiles of striped catfish (Pangasianodon hypophthalmus). 400 fish with an initial average weight of 1.54 ± 0.02g were randomly divided into five groups and fed with different concentration of M. tuberosa Jack leaves extract (0.25, 0.5, 1, 2%) and control diet for 80 days. Growth performance, feed conversion rate, feed efficiency, survival rate, morphometric, and hematological profile of the fish were evaluated at the end of the trial. The results found that fish fed 0.5-1% concentration had significantly higher (P<0.05) growth, feed conversion rate, feed efficiency, morphometric value, survival, white blood cell, hemoglobin, neutrophil, lymphocyte, and monocyte than control. Meanwhile, supplementation of 2% MTE in the diet of fish reduced growth, feed utilization, viscerosomatic index, and morphometric values but increased red blood cell. All the supplemented diets decreased platelet of fish. The findings indicated that supplementation 0.5-1% of MTE is beneficial to the growth and blood profile of fish through the increment of growth indices, feed utilization, white blood cell, hemoglobin, neutrophil, lymphocyte, and survival rate of fish.

Impact of Wuyiencin Application on the Soil Microbial Community and Fate of Typical Antibiotic Resistance Genes

Antibiotic resistance genes (ARGs) have raised numerous concerns in recent years as emerging environmental contaminants. At present, research on environmental contamination by antibiotics focuses on medical, animal husbandry, and aquaculture fields, with few studies on environmental contamination by agricultural antibiotics in the field of plant protection. Wuyiencin is a low toxicity, high efficiency, and broad-spectrum agricultural antibiotic. It has been widely used in agricultural production and it effectively controls crop fungal diseases. In the present study, pot experiments with four soil treatments (A, B, C and D) were set up in a greenhouse to investigate the effect of the application of wuyiencin on the fate of typical ARGs and microbial community. Eight typical ARGs were detected by real-time PCR and the microbial communities were analyzed using high-throughput sequencing. The results showed that wuyiencin neither significantly influenced ARG abundance and absolute gene copy numbers, nor significantly varied microbial community among treatments. Since it only was short-term results, and the detection number of ARGs was limited, whether wuyiencin is safe or not to ecological environment when using for long-term will need further deep research.

Surface modifications by plasma treatment, chemical grafting and over dyeing of polyamide nets to improve the antifouling performance in the aquaculture field

Surface modifications by plasma treatment, chemical grafting and over dyeing of polyamide nets to improve the antifouling performance in the aquaculture field