Relevance For Aquaculture Research Articles

Aeromonas salmonicida AI-1 and AI-2 quorum sensing pathways are differentially regulated by rainbow trout mucins and during in vivo colonization

Aeromonas salmonicida is an opportunistic pathogen with relevance for aquaculture. Fish epithelia are covered by a mucus layer, composed mainly by highly glycosylated mucins, which are the first point of contact between fish and pathogens. Quorum sensing (QS), a bacterial communication mechanism through secreted autoinducer signals that governs gene expression, influences bacterial growth and virulence. The main A. salmonicida autoinducers are mediated by the luxS and asaI genes, corresponding to inter- and intraspecies communication, respectively. The aim of this study was to determine the effect of the mucins that pathogens encounter during colonization of the gill and skin on A. salmonicida QS. We found that expression of A. salmonicida asaI, but not luxS, was increased after culture at 20 °C compared to 10 °C. Rainbow trout gill and skin mucins up-regulated asaI expression 2-fold but down-regulated luxS 10-fold. The downregulation of luxS was reflected by a reduction in autoinducer-2 secretion. Mucins isolated from skin had a stronger inhibitory effect than mucins isolated from gills on both luxS expression and A1-2 secretion, consistent with a higher relative abundance of N-Acetylneuraminic acid on skin mucins than on gill mucins. Reduction of AI-2 production by mucins or luxS-deletion lead to a reduced A. salmonicida auto-aggregation. Furthermore, after colonization of the gill, luxS was down regulated whereas asaI expression was upregulated. Both in vivo and in vitro, the expression of luxS and asaI were thus differentially regulated, frequently in an inverse manner. The strong AI-2 inhibiting effect of the skin mucins is likely part of the mucin-based defense against pathogens.

Humanizing aquaculture development: Putting social and human concerns at the center of future aquaculture development

AbstractCompared with other aquaculture issues, attention to human and social dimensions is lagging behind. Sectoral development, policy, and programmatic factors have created inequities and sub‐optimal social outcomes, which are jeopardizing the broader contribution the sector could make to human well‐being. Human rights in aquaculture are at the core of this article, which argues that aquaculture development, as a major economic and food producing sector, needs to be about human development. The article reviews: the application of human rights in aquaculture, and the related right to decent work; the notions of justice and equity including the idea of Blue Justice and its relevance in aquaculture; and ethics and social license to operate with the challenges that business ethics and public acceptance pose to the sector. It also reviews how these issues affect people: women, along with slow progress in gender equality in the sector; youth and their engagement in aquaculture, while noting that ‘youth’ does not equate to “jobs” and requires the lifting of many more societal hurdles for their full participation in the sector; indigenous people and local ecological knowledge—a precious asset for future aquaculture as well as the survival and enhancement of the cultural value of aquaculture; and people with disabilities and other minorities who have yet to become fully visible and accounted for in aquaculture development. Redressing human and social issues in aquaculture, and placing people at the center of aquaculture development requires a fundamental change from business as usual. To humanize aquaculture development, a renewed human relationship with aquaculture is proposed, which is founded on recognizing substantive equality and agency, embracing intersectionality, that is, the multiple social dimensions of identity and interaction, and valuing cross‐disciplinary knowledge systems. It would be implemented through new, inclusive, business models, social provisioning approaches, and procedural justice and governance mechanisms for overcoming inequalities. Public, private, and non‐state actors will need to be involved, inclusive of small‐scale farmers, women, youth, people with disabilities, and indigenous communities as key groups. Six key messages conclude the article.

MiRTil: An Extensive Repository for Nile Tilapia microRNA Next Generation Sequencing Data.

Nile tilapia is the third most cultivated fish worldwide and a novel model species for evolutionary studies. Aiming to improve productivity and contribute to the selection of traits of economic impact, biotechnological approaches have been intensively applied to species enhancement. In this sense, recent studies have focused on the multiple roles played by microRNAs (miRNAs) in the post-transcriptional regulation of protein-coding genes involved in the emergence of phenotypes with relevance for aquaculture. However, there is still a growing demand for a reference resource dedicated to integrating Nile Tilapia miRNA information, obtained from both experimental and in silico approaches, and facilitating the analysis and interpretation of RNA sequencing data. Here, we present an open repository dedicated to Nile Tilapia miRNAs: the “miRTil database”. The database stores data on 734 mature miRNAs identified in 11 distinct tissues and five key developmental stages. The database provides detailed information about miRNA structure, genomic context, predicted targets, expression profiles, and relative 5p/3p arm usage. Additionally, miRTil also includes a comprehensive pre-computed miRNA-target interaction network containing 4936 targets and 19,580 interactions.

Gold nanoparticles (AuNP) exert immunostimulatory and protective effects in shrimp (Litopenaeus vannamei) against Vibrio parahaemolyticus

Gold nanoparticles (AuNP) stimulate immune responses in mammals but they have not been tested in species of relevance in aquaculture. In this study the immunostimulant and protective potential of orally administered AuNP against V. parahaemolyticus, the causative agent of Acute Hepatopancreatic Necrosis Disease, was determined in shrimp. Synthetized AuNP (18.57 ± 4.37 nm) were moderately dispersed with a negative ζ potential of −10.3 ± 0.208 mV (pH = 7). AuNP were administered (single dose) at 0.2, 2, and 20 μg/g feed in shrimp. Hemolymph samples were withdrawn daily for 6 days. Hemolymph or hemocytes were used to determine total hemocyte counts, immune-related enzymatic activities, and expression of immune-relevant genes. Hepatopancreas was sampled for the analysis of AuNP biodistribution and histological examination. Survival was recorded daily. No mortality or toxicity signs in hepatopancreas were found. AuNP were detected in hepatopancreas. Early (24–48 h) immunostimulation was mainly related to immune gene up-regulation. Upon a challenge with V. parahaemolyticus, survival was higher (80%) and histopathological damages were lower in shrimp treated with the 2 μg/g dose when compared to the control. Therefore orally administered AuNP are proposed as immunostimulants that protect shrimp against V. parahaemolyticus infection.

Trade-offs between timing of metamorphosis and grow-out performance of a marine caridean shrimp juveniles and its relevance for aquaculture

Information on the aquaculture performance of marine caridean shrimp is still scarce when compared with that of freshwater species (e.g. Macrobrachium spp.) or penaeids. Moreover, most studies addressing shrimp aquaculture focus either larval performance or juvenile grow-out, with the vast majority overlooking the potential existence of carry-over effects from one life stage to the next. Such effects in phenotypic traits may be expressed when species undergo dramatic shifts, such as at metamorphosis. The present study evaluated the existence of potential trade-offs between the timing of metamorphosis and the grow-out performance displayed by juvenile marine caridean shrimp using Lysmata seticaudata, a marine ornamental species, as model. Larvae that delayed metamorphosis for longer periods (termed as late settlers – LS) gave origin to significantly larger sized post-larvae (7.37 ± 0.25 mm total length), than that displayed by early or middle settlers (ES and MS, 6.95 ± 0.28 mm and 7.02 ± 0.24 mm, respectively). However, at the end of the grow-out period juvenile shrimp originating from LS postlarvae displayed a significantly smaller TL (10.38 ± 0.82 mm) than that displayed from conspecifics originating from ES and MS (11.20 ± 1.02 and 11.22 ± 0.62 mm, respectively). The larger size attained by L. seticaudata post-larvae originating from specimens that delayed metamorphosis (LS) is likely achieved by trading-off endogenous energetic reserves that, once allocated to delay the transition to benthic life will no longer be available to help fueling early juvenile growth. The present work suggests that a detailed record on the timing of metamorphosis can be a more reliable proxy to access the grow-out performance of juvenile marine caridean shrimp than postlarval size at metamorphosis. An optimal aquaculture of organisms with complex life-cycles, such as decapod crustaceans, relies on the detailed knowledge of each life stage performance, as the exposure to suboptimal conditions during early life stages may give origin to phenotypic traits that are carried-over and only displayed later in the life cycle (e.g. post-metamorphosis).

Dissolution rate of calcium carbonate and calcium hydroxide in saline waters and its relevance for aquaculture

The solubilities of calcium carbonate and calcium hydroxide were determined in four waters of different initial salinity, pH, and alkalinity (in parentheses, respectively) as follows: freshwater (0.01gL−1, 6.26, 2.79mgL−1); diluted seawater (3.7gL−1, 7.37, 13mgL−1); diluted seawater (11.0gL−1, 7.97, 35.3mgL−1); seawater (31.7gL−1, 8.12, 109.1mgL−1). Calcium carbonate (97% pure) was added to four 2000-mL flasks of each water at 1.00g each. After 32days, the pH was between 8.1 and 8.3 in all flasks. Alkalinity reached approximately 60mgL−1 in waters initially at 0.01, 3.7, and 11.0gL−1 salinity. In the seawater, alkalinity decreased slightly after 32days. Analysis of results suggested that alkalinity would not increase at a Langelier saturation index of 0.62 or more. Flasks of seawater were treated with calcium hydroxide at rates of about 0, 12, 25, and 76mgL−1 of Ca(OH)2. The pH 24h after treatment ranged from around 8.2 to 8.6. Results of this study revealed that calcium carbonate does not dissolve in seawater and that the equilibrium alkalinity concentration in lower salinity water was about 60mgL−1. Calcium hydroxide – even at 75mgL−1 – did not cause a large increase in pH of seawater. These findings cast serious doubt on the effectiveness of the widespread use of agricultural limestone and lime in shrimp aquaculture ponds.

People matter in animal disease surveillance: Challenges and opportunities for the aquaculture sector

Recurring epidemics and the emergence of new aquatic diseases are increasingly threatening the growth of aquaculture. The fast pace of aquaculture development and on-going global environmental, social and economic change are challenging epidemiologists in their capacity to surveil and control the spread of diseases and avert losses to farmers and impacts on their livelihoods and environment. By placing farmers as the starting point of disease surveillance, we contend that farmer-based syndromic disease surveillance holds potential to overcome the current limitations of conventional disease surveillance, and demonstrate its relevance for aquaculture, particularly in resource constrained environments. Drawing on the literature on aquaculture, epidemiology, farmers' decision-making, technology adoption in animal health management and participation in animal disease surveillance, we highlight the complex interplay of behavioural (economic and social) factors behind farmers' reporting of disease. To this we add insights from institutional economics to analyse the constraints and dilemmas disease surveillance poses to institutions. Whilst information technologies are playing a significant supporting role in disease surveillance, our central argument is that if data collection for epidemiological monitoring is about technology, surveillance itself is about people. Stakeholder involvement and perception of surveillance benefits, value of epidemiological data collected, farmers' knowledge, motivation and trust and institutions' functioning are key considerations in the design of successful syndromic disease surveillance programmes. These human dimensions constitute important knowledge gaps in animal disease surveillance in general, and in particular in aquaculture. Interdisciplinary collaboration in disease surveillance is essential. It is crucial in an environment where diseases are emerging and spreading in increasingly complex, interconnected and dynamic social-ecological systems and is the key to unlocking the numerous benefits of farmer-based syndromic aquatic disease surveillance.

Differential expression of X-box binding protein 1 during ovarian development and association between its SNP and growth-related parameters of the giant tiger shrimp Penaeus monodon

Abstract The full-length cDNA of X-box binding protein 1 ( PmXbp1 ) in the giant tiger shrimp, Penaeus monodon was identified. It was 1762 bp in length containing an ORF of 855 bp corresponding to 284 amino acids. The expression level of PmXbp1 in different ovarian stages of wild intact broodstock was comparable but greater than that of cultured juveniles ( P PmXbp1 in stages III (late vitellogenic) and IV (mature) ovaries of wild P. monodon broodstock ( P PmXbp1 in ovaries of domesticated 18-month-old broodstock at 24 hpi ( P PmXbp1 (185 bp) were examined in domesticated 3-month-old juveniles (average body weight and total length = 12.32 ± 5.13 g and 11.30 ± 1.58 cm, N = 162) by single-strand conformational polymorphism (SSCP) analysis. Association between SSCP patterns of PmXbp1 and growth-related parameters was found where the average body weight (15.07 ± 5.04, N = 44) of juveniles carrying pattern A (corresponding to a T/T 349 SNP) was significantly greater than that (11.37 ± 4.80, N = 116) of juveniles carrying pattern B (corresponding to a T/C 349 SNP). The relative expression levels of PmXbp1 in the hepatopancreas of juveniles carrying different SSCP/SNP genotypes were significantly different (A P PmXbp1 in shrimp exhibiting a greater growth performance (22.08 ± 2.97 g and 13.60 ± 0.56 cm; N = 11) was significantly lower than that with a lesser growth performance (5.00 ± 0.89 g and 8.60 ± 0.98 cm; N = 8) ( P PmXbp1 seems to play an important role in reproduction and growth of P. monodon . Statement of relevance In aquaculture, the primary goal of genetic selection is the growth improvement of economically important species. Molecular markers that allow for selection of juveniles and broodstock with a high breeding value for reproductive maturation and/or growth rates are useful for the shrimp industry. Information on correlation between genotypic and phenotypic variations in penaeid shrimp is rather limited. Identification of molecular markers linked with growth/reproduction or those regulating the growth/reproduction mechanisms can be applied to improve artificial selection processes of P. monodon . To assess the possible biological roles of X-box binding protein 1 in reproduction and growth of P. monodon , the PmXbp1 cDNA sequence was characterized. Expression patterns of PmXbp1 during ovarian development in wild P. monodon broodstock were examined. Effects of eyestalk ablation (wild broodstock) and serotonin induction (domesticated broodstock) on expression levels of ovarian PmXbp1 were examined. In addition, analysis of relationships between SNP detected by SSCP and DNA sequencing and expression levels of PmXbp1 , and growth traits in juvenile shrimp was examined.

Effect of zeolites on cultures of the marine micro-algae Emiliania huxleyi

The yield of cultures of Emiliania huxleyi, a coccolithophore marine micro-alga species, in natural seawater and in seawater previously exposed to elutriates of ZEBEN-06 and ZESTEC-56, two zeolitic-nature products (ZNPs) (supernatant of 2.0gl−1 of ZNP in natural seawater, stirred for 30min) was evaluated. Total concentrations of dissolved trace metals and organic ligands (and respective conditional stability constants) in the initial media and at 7th day cultures were determined, by anodic and cathodic striping voltammetry. The changes introduced by the ZNPs in the media significantly enhanced E. huxleyi growth yield, the effect being more extent in the ZESTEC-56 elutriate. It was observed that both the ZNPs enriched the seawater with trace and not toxic quantities of Mn. In addiction, ZEBEN-06 removed small fractions of Cu and Zn from the media. The ZEBEN-06 elutriate stimulated the cell exudation but that of ZESTEC-56 inhibited exudation. Algae were also incubated in a culture medium with 0.05gl−1 ZESTEC-56 in situ, and the growth yield was similar to that of the control culture. ZEBEN-06 was not studied in situ because it was hard to distinguish its particles from the cells, during cells counting. The ZESTEC-56 in situ enriched the medium in Mn, Cu, Pb and Cd, but impoverished it in Zn. The cell exudation was about four times higher in the presence of the ZNP in situ. Liberation/adsorption of micro-nutrients at the surface of the zeolites seems to be the cause of the observed changes in the biological response of the algae. The yield of the algal growth has economic relevance in aquaculture. On the other hand, ZNP are cheap, only small amounts (few mgl−1) are required and the addition of some nicro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may be economically advantageous. However, it is recommendable an previous investigation, in order to select the zeolitic characteristics and concentration that will maximise the algal yield in each particular case (alga nature and seawater trace metal contents).

Effect of zeolites on cultures of the marine micro-algae Emiliania huxleyi

The yield of cultures of Emiliania huxleyi , a coccolithophore marine micro-alga species, in natural seawater and in seawater previously exposed to elutriates of ZEBEN-06 and ZESTEC-56, two zeolitic-nature products (ZNPs) (supernatant of 2.0 g l −1 of ZNP in natural seawater, stirred for 30 min) was evaluated. Total concentrations of dissolved trace metals and organic ligands (and respective conditional stability constants) in the initial media and at 7th day cultures were determined, by anodic and cathodic striping voltammetry. The changes introduced by the ZNPs in the media significantly enhanced E. huxleyi growth yield, the effect being more extent in the ZESTEC-56 elutriate. It was observed that both the ZNPs enriched the seawater with trace and not toxic quantities of Mn. In addiction, ZEBEN-06 removed small fractions of Cu and Zn from the media. The ZEBEN-06 elutriate stimulated the cell exudation but that of ZESTEC-56 inhibited exudation. Algae were also incubated in a culture medium with 0.05 g l −1 ZESTEC-56 in situ, and the growth yield was similar to that of the control culture. ZEBEN-06 was not studied in situ because it was hard to distinguish its particles from the cells, during cells counting. The ZESTEC-56 in situ enriched the medium in Mn, Cu, Pb and Cd, but impoverished it in Zn. The cell exudation was about four times higher in the presence of the ZNP in situ. Liberation/adsorption of micro-nutrients at the surface of the zeolites seems to be the cause of the observed changes in the biological response of the algae. The yield of the algal growth has economic relevance in aquaculture. On the other hand, ZNP are cheap, only small amounts (few mg l −1 ) are required and the addition of some nicro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may be economically advantageous. However, it is recommendable an previous investigation, in order to select the zeolitic characteristics and concentration that will maximise the algal yield in each particular case (alga nature and seawater trace metal contents).

Advances in economics of marketing and implications for aquaculture development

This paper builds on an earlier review by Kinnucan and Wessells (1997) by discussing in some detail product differentiation, market integration, and generic advertising. The goal is to identify approaches and findings in each topical area that would appear to have relevance for aquaculture. Selected applications are given to highlight principles and to demonstrate usefulness.