Immunostimulatory effects of dietary poly‐β‐hydroxybutyrate in European sea bass postlarvae

The stable production of high‐quality fry in marine aquaculture is still hampered by unpredictable mortality caused by infectious diseases during larval rearing. Consequently, the development of new biocontrol agents is crucial for a viable aquaculture industry. The bacterial energy storage compound poly‐β‐hydroxybutyrate (PHB) has been shown to exhibit beneficial properties on aquatic organisms such as enhanced survival, growth, disease resistance and a controlling effect on the gastrointestinal microbiota. However, the effect of PHB on the developing immune system of fish larvae has so far not been investigated. In this study, the effect of feeding PHB‐enriched Artemia nauplii on survival, growth and immune response in European sea bass (Dicentrarchus labrax) postlarvae was examined. Amorphous PHB was administered to 28‐day‐old sea bass postlarvae over a period of 10 days. The survival and growth performance were monitored, and the expression of 29 genes involved in immunity, growth, metabolism and stress‐response was measured. While the expression of the insulin‐like growth factor 1 (igf1), an indicator of relative growth, was upregulated in response to feeding PHB, the larval survival and growth performance remained unaffected. After 10 days of PHB treatment, the expression of the antimicrobial peptides dicentracin (dic) and hepcidin (hep) as well as mhc class IIa and mhc class IIb was elevated in the PHB fed postlarvae. This indicates that PHB is capable of stimulating the immune system of fish early life stages, which may be the cause of the increased resistance to diseases and robustness observed in previous studies.     

A sensory and nutritional validation of open ocean mussels (Mytilus galloprovincialis Lmk.) cultured in SE Bay of Biscay (Basque Country) compared to their commercial counterparts from Galician Rías (Spain)

Mussel shell biometry, nutritional quality as well as consumer sensory evaluation of experimental open ocean cultured mussel Mytilus galloprovincialis (Lamarck 1819) were analyzed and compared to that of commercial mussels from Galician Rías available in the local market. Both mussel products were of the same commercial size. In this study, open ocean mussels were significantly higher and wider than those of Galician Rías. In addition, with the exception of ash content, both mussel products showed similar biochemical composition. Regarding fatty acid profiles, however, statistical differences were detected. These differences were not fully reflected in the sensory assessment. In terms of consumer acceptability, both mussel products were considered equally satisfactory.

     

Effects of three culture densities on growth and survival of <Emphasis Type="Italic">Octopus vulgaris</Emphasis> (Cuvier, 1797)

The purpoase of this research was to test the effects of three culture densities on the growth and survival of Octopus vulgaris. A total of 141 sub-adult octopuses (1,175.4 ± 194.9 g) were randomly distributed in nine tanks of 2,000 l each (3.6 m × 1.1 m, and 50 cm water depth). Three tanks were stocked with a low initial density of 4 kg/m³, while three other tanks were stocked with an initial density of 8 kg/m³, and the remaining three tanks were stocked at an initial density of 15 kg/m³. Octopuses were all fed frozen squid (Loligo gahi) at 5% body weight per day (%BW/day). The experiment lasted for 70 days. Water temperature varied between 20 ± 2°C, and salinity varied between 36 ± 1 ppt. During the entire experiment, dissolved oxygen was always >75%, and ammonia was always lower than 0.1 mg/l. No differences in growth or growth rates (between 0.9 and 1.1%BW/day for the three densities) were found. Nevertheless, mortality was significantly lower for the low density compared to the other two densities tested. Maximum densities in the culture tanks (>25 kg/m³) were attained in the higher culture densities after 56 days of the experiment.     

Extensive cage culture of pejerrey (Odontesthes bonariensis) in a shallow pampean lake in Argentina

Pejerrey is an important zooplanktivorous native fish of the Argentinean inland waters. It has been traditionally propagated for stocking purposes by relatively costly semi‐intensive and intensive methods. In this study, we evaluated the implementation of an extensive culture method by using floating cages in a shallow pampean lake. Four cages were installed in the Lacombe Lake and stocked with juveniles (16.24 ± 1.69 mm length) at 50 fish m^?3 density for growing until the size of 150 mm, which is considered as a suitable size for stocking. Throughout the experiment, the temperature ranged between 10 and 26 °C and the zooplankton biomass ranged between 12 and 3269 μg dw L^?1. The growth patterns in the length were similar in the four cages and directly related to the lake thermal conditions and zooplankton availability. The average final length after 315 days was 154.4 ± 8.8 mm. The survival rates ranged between 53.5% and 64.7% during the first 110 days and 11.1–25.7% at termination. Growth rate for the first 2 months was the highest documented for pejerrey culture. This simple technique offers the possibility to produce juvenile pejerrey at a low cost and provides the alternative of reinforcing the natural populations with fish already adapted to the natural environmental conditions.     

A Study of Lipid Bioaccessibility in Canned Sardine (Sardina pilchardus) and Chub Mackerel (Scomber japonicus)

The lipid composition and bioaccessibility in canned sardine (Sardina pilchardus) and chub mackerel (Scomber japonicus) were studied. Triacylglycerols were absent from the bioaccessible fraction in both products and each FA had a different bioaccessibility level. While total fat bioaccessibility was in the 60–64% range, the bioaccessibility of ω6 PUFA and DHA was <55%. Bioaccessibility depended on canned fish product species: fat, EPA, DHA, and ω3 PUFA bioaccessibility levels seemed to be higher in canned sardine than in canned mackerel. Daily consumption of 278 g of canned mackerel or 47 g of canned sardine would ensure the recommended daily intake of EPA+ DHA.     

First attempts towards the restoration of gorgonian populations on the Mediterranean continental shelf

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Rhetoric and reality of reforestation methods for soil and water conservation in Guadalajara (Spain)

Foresters have played an important part in the Spanish national strategy against land degradation. It might be expected that after the changes restored political democracy in Spain in the late 1970s, a reorganization of the way the planning and implementation of soil and water conservation projects through reforestation would be changed. This paper considers the case of Guadalajara province as an example of the way in which reforestation has been effected at national level, and the consequences for the ecosystem. It examines how, since the 1940s, the technical methods used by forestry technicians have changed from concerns with protection to those of wood production. Although reforestation methods for wood production have been recognized as detrimental to soil and water conservation, they continue to be used even in the face of considerable opposition by local people and environmental pressure groups. The paper concludes that claims for soil protection mask a policy of wood production, excluding affected people from the decision-making process. Copyright © 1999 John Wiley & Sons, Ltd.     

Habitat characterization,anthropogenic impacts and conservation of rhodolith beds off southeastern Malta

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