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.     

Molecular phylogenetic,morphological, and pathogenic analyses reveal a single clonal population of Septoria lycopersici with a narrower host range in Brazil

Septoria leaf spot, caused by Septoria lycopersici, is considered one of the most important diseases of tomato in Brazil. Despite its importance, the disease agent is still poorly studied. Septoria isolates collected from different production regions of Brazil were characterized by molecular, morphological, and pathogenic methods. A set of 104 isolates was sequenced for the DNA Tub, Cal, and EF1-α loci. Ten isolates were selected, according to geographical region of origin and type of leaf lesion (typical or atypical), for morphological characterization and for evaluation of aggressiveness on tomato cultivar Santa Clara. To evaluate the pathogen host range, cultivated and wild Solanaceae plants were inoculated with four selected isolates. The results showed that all isolates grouped with the type isolate of S. lycopersici in maximum likelihood and Bayesian inference trees. The isolates were morphologically similar. All isolates selected for pathogenicity testing on tomato were able to induce typical symptoms of the disease, but differed in their aggressiveness. A total of eight species of Solanaceae were also identified as potential alternative hosts for S. lycopersici. This information will provide a more accurate assessment of the risks involved with the introduction of new crops, especially of the genus Solanum, in areas where the species is already present. In addition, it will provide the basis for the establishment of more efficient methods in the management of Septoria leaf spot of tomatoes in natural conditions and in the different production systems.     

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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A combination of plant oils promotes adequate growth of the freshwater catfish Rhamdia quelen (Quoy & Gaimard 1824)

Essential fatty acids should be included in the diet to ensure adequate fish growth. Despite the great number of studies on fatty acid nutrition of fish, there are still several unknowns. The aim of the present study was to investigate fatty acid nutrition of jundiá, a Latin American freshwater catfish. Four diets were formulated containing (i) coconut oil (?C, negative control), (ii) coconut oil + high‐docosahexaenoic‐acid‐fish oil (+C, positive control) and coconut + sunflower + linseed oils at different ratios, producing either (iii) a diet rich in linoleic acid (LA) (HighLA) or 4) a diet low in LA (LowLA). All diets contained significant amounts of saturated fatty acids (at least 57.5% total fatty acids in HighLA) and monounsaturated fatty acids (at least 19.1% total fatty acids in ?C). Diets were fed to jundiá fingerlings (1.5 g) for 70 days; growth, body composition and liver histology were evaluated. The ?C diet, without essential fatty acids, promoted significantly lower fish growth, body fat accumulation and hepatic lipidosis. Fish fed HighLA and LowLA diets presented similar growth as fish fed +C diet. These findings suggest that diet formulations for jundiá catfish fingerlings can include only plant oils without negative effect on growth, survival, body composition, fish health or parameters of feed utilization (ingestion rate and protein utilization).     

Factors impacting blackleg development caused by Dickeya spp. in the field

Stem rot symptoms caused by pectinolytic bacteria of Genus Pectobacterium and Genus Dickeya, which are commonly referred to as blackleg, strongly impact the quality of seed potato production in most European countries. Several biotic and abiotic factors, such as cultivar susceptibility, isolate aggressiveness, mother tuber infection density and a wide range of soil-related and climatic factors have been identified in the literature as having an effect on blackleg development. The aim of this study was to identify which biotic and/or abiotic factors are most critical to the development of blackleg in the field. In Switzerland, the predominant species have belonged to Genus Dickeya as far back as 1992, which is why this study only investigates blackleg symptoms induced by Dickeya isolates. Seven field trials, in which inoculated tubers were planted, were conducted during a 3-year period and the number of blackleg-diseased plants was counted. Multiple regression analysis was used in order to determine the factors that had the greatest impact on two different variables: (i) periods between emergence of the plant and disease outbreak and (ii) overall blackleg incidence throughout the growing season. The results of this analysis have revealed that environmental factors, such as evapotranspiration and soil moisture, explain about half of the variability in the number of days before disease outbreak, and the total number of diseased plants is widely dependent upon cultivar susceptibility and isolate aggressiveness.