Rearing European brown shrimp (Crangon crangon, Linnaeus 1758) : a review on the current status and perspectives for aquaculture

The European brown shrimp, Crangon crangon, is a highly valued commercial species fished in the north-eastern Atlantic, especially the North Sea. The shrimp fisheries are mainly coastal and exert high pressures on the local ecosystems, including estuaries. The culture of the species provides an alternative to supply a niche market I(large live/fresh shrimps) in a sustainable manner. However, after more than a century of biological research on this species, there is still little knowledge on its optimal rearing conditions. C. crangon remains a difficult species to keep alive and healthy for an extended period of time in captivity. This review is based on a comprehensive literature search and reflects on the current status of experimental rearing techniques used for this species, identifies the problems that compromise the closing of the life cycle in captivity and provides examples on how these problem issues were solved in the culture of commercial shrimp species or other crustaceans. The ability to consistently produce high-quality offspring could initiate the commercial production of this valuable shrimp. A further advantage of the ability to consistently produce high-quality offspring of this species would facilitate research on the development of new bio-assays with this ecologically and economically important species in a wide variety of biochemical and physiological studies

Development and validation of the in vivo alkaline comet assay for detecting genomic damage in marine flatfish

Biomonitoring is an important subject within environmental sciences. Biomonitoring tests are required to be quick, relatively inexpensive, accurate, and reproducible. No genetic test currently fulfils all of these requirements. The chromosome aberration and sister chromatid exchange tests are very time consuming, the DNA adduct technique is rather expensive, and the micronucleus test has not inconclusively proven its use as a reliable monitoring tool. This work is focused on the validation of the comet assay as a candidate for monitoring marine ecosystems. For the comet assay, this work deals with the effectiveness of tissue dissociation, storage of cells in lysing buffer and in liquid nitrogen, different electrophoretic conditions, neutralisation and fixation of slides, interindividual variation between samples, and responsiveness of four tissue types to ethyl methanesulphonate (EMS). The main conclusions are: (i) dissociation of solid tissues in a phosphate buffer supplemented with 200 mM N-t-butyl-α-phenylnitrone provides cells with an acceptable background DNA damage; (ii) freezing of cells or tissues in liquid nitrogen generally leads to an increase in DNA breakage, especially for liver, gill and kidney tissue; (iii) storage of slides in the lysing solution for up to one week gives minor changes in comet tails; (iv) differences in protocols for neutralisation and fixation may influence the results; (v) high intra- and interindividual variations in comets (length and DNA content) may obscure the interpretation of comet results; (vi) blood, gill, liver and kidney all showed a statistically significant increase of DNA damage after exposure to 50 mg EMS/l; (vii) electrophoresis at low voltage for longer periods is to be preferred to high voltage and short electrophoresis times. The simplicity and sensitivity of the comet assay make it an adequate test system for biomonitoring of chronic low level exposure. However, protocols and experimental conditions have to be chosen carefully. Copyright (C) 1998 Elsevier Science B.V.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Investigating Features of Chain-wide Sustainability Initiatives Favouring Sustainable Development in Flemish Agriculture

Sustainable development can be described as ‘wicked problem’ without fixed end goals or templates to achieve it. Suggestions to start challenging our existing practice resulted in a number of initiatives stimulating farmers to increase the sustainability of their farming practices. These initiatives are very diverse with respect to the actors involved, the tools used, the setting in which it takes place, etc. The contestable, normatively and revolutionary concept of sustainability calls for learning as an essential element of projects and practices seeking contribution to a sustainable development. Insights on how and if these initiatives influence the sustainable development of farming practices are lacking. Therefore we try to find out the kind of learning necessary to achieve a sustainable development of farming practices through literature on Education for Sustainable Development (ESD) and educational practices. Based on a framework of Lankester, we ordered a non-limitative list of characteristics of educational processes mentioned in literature in categories ‘who learns’, ‘why is learned’, ‘how is learned’, ‘what is learned’. These characteristics will be used to analyze four cases where farmers are stimulated to increase the sustainability of their farm. Two of these initiatives are located in The Netherlands (Veldleeuwerik’ and ‘Koeien en kansen’) and two are located in Belgium (‘Beloftevol Boeren’ and ‘Boerenbond duurzaamheidstraject’). Based on this analysis, we derive recommendations on how the educational dynamic within these practices can be further stimulated and farmers learn to deal with sustainability as a wicked problem.status: publishe

Improvements in larviculture of Crangon crangon as a step towards its commercial aquaculture

The European brown shrimp, Crangon crangon, is a highly valued commercial species in Europe. These shrimp fisheries are characterized by strong seasonal variations in average landings. Attempts to 'catch and hold' wild adults in land-based rearing systems have been proven to be very difficult, due to inadequate feed, slow growth and high mortality. In this study, we have optimized design and operation procedures of a small-scale static larval rearing system for the culture of C. crangon larvae. Focus was on optimizing larval survival via water temperature, feed selection, feeding regime and density. This is the first report that shows that C. crangon larvae can be reared at high densities of 300 larvae L-1 with high survival of 73.5 (+/- 5.4)% under laboratory conditions. In these systems, larvae can be fed exclusively Artemia nauplii according to a feeding regime which is adjusted based on major moulting events. Addition of microalgae may further increase survival by 10%. The information gathered during this research can be applied to further optimize larval development in either flow-through or recirculation systems

The heterodimeric ecdysteroid receptor complex in the brown shrimp Crangon crangon: EcR and RXR isoform characteristics and sensitivity towards the marine pollutant tributyltin

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