Phaeobacter grown in biofilters: a new strategy for the control of Vibrionaceae in aquaculture

Growth, biofilm formation, antagonism and residence time in green seawater tanks maintained under fish rearing conditions of Phaeobacter 27‐4 were studied in commercial biofilters made from plastic, sintered glass and ceramic. Phaeobacter reached 10⁸–10⁹ CFU cm^?3 and formed rosettes in all materials, but a multilayer biofilm was only observed in the ceramic biofilters. In sterile seawater, plastic and ceramic biofilters reduced Vibrio anguillarum and V. splendidus concentration in one‐two Log after 24–48 h, showing 10²–10³ CFU mL^?1. Sintered glass biofilters only inactivated V. anguillarum. In Marine Broth, sintered glass and ceramic biofilters inhibited V. anguillarum growth in two‐three Log, showing 10⁴–10⁵ CFU mL^?1 after 24 h. Plastic biofilters reduced V. anguillarum concentration in one Log after 48 h. V. splendidus growth was only inhibited by sintered glass and ceramic biofilters in one‐two Log, showing 10⁷ CFU mL^?1 after 24 h. Phaeobacter also diminished biofilters colonization by the pathogens, both in seawater and in MB. Phaeobacter residence time in green seawater tanks maintained under fish rearing conditions was longer with sintered glass and ceramic biofilters. The latest showed the lowest detachment and, after 11 days, Phaeobacter (10⁶ bacteria·cm^?3) covered more than 80% of biofilters total culturable bacteria. DGGE profiles showed that Phaeobacter biofilters stabilizes the green seawater bacterial microbiota.     

Effect of different fertilisation and irrigation practices on yield,nitrogen uptake and fertiliser use efficiency of white cabbage (Brassica oleracea var. capitata L.)

The effect of different fertilisation (i.e. broadcast application and fertigation) and irrigation practices (tank sprinkler and drip irrigation) on yield, yield quality (nitrate content), nitrogen uptake of white cabbage (Brassica oleracea var. capitata L.) and the potential for N losses was assessed on sandy-loam agricultural soil. ¹⁵N-labelled fertiliser was used as a tracer. It was found that different practices significantly affected yield, nitrate content in plants, N uptake, as well as fertiliser use efficiency. The highest yield (93 t ha⁻¹), plant N uptake (246 kg ha⁻¹), and fertiliser use efficiency (42%) were obtained under treatment with broadcast fertilisation with farmer's practice of irrigation (tank sprinkler). The N surplus after harvest was −41 kg N ha⁻¹, indicating the lowest potential for N losses. Treatment by fertigation and drip irrigation covering 100% of the crop's water requirements did not result in the highest yield as expected (72 t ha⁻¹), the N surplus after harvest was about +38 kg ha⁻¹. The lowest yield (58 t ha⁻¹), fertiliser use efficiency (30%) and hence the highest potential for N losses (N surplus after harvest +68 kg ha⁻¹) were found in treatment with broadcast fertilisation and drip irrigation covering 50% of the crop's water requirements.     

Assessment of polycyclic aromatic hydrocarbons in biochar and biochar-amended agricultural soil from Southern Spain

Journal of Soils and Sediments - The goal of this study was to determine if the application of four biochars produced from different feedstock leads to soil contamination with the 16 US...     

The common carp <Emphasis Type="Italic">Cyprinus carpio</Emphasis> in Croatia (Danube and Adriatic basins): a historical review

This review provides the first historical account of the ecology and biology of common carp Cyprinus carpio in the Danube and Adriatic basins of Croatia, and emphasises the species’ economic relevance and management implications. As a semi-native species that is native to the Danube but translocated across the Adriatic Basin, carp plays an important role for aquaculture, recreational and artisanal fisheries. However, original strains have now disappeared, and because of genetic pollution in inland waters there is an increasing demand for restoring populations of the now rare and threatened wild carp, making conservation measures a priority. Translocations of carp across water bodies of the Adriatic Basin mostly for food supply did not prove successful in the long term, as the resulting ecological impacts may have been higher than the expected economic advantages. Measures for the prevention of further (uncontrolled) carp re-stocking are therefore necessary and this will require closer collaboration between scientists and environmental managers.     

The effect of density in larval rearing of the pullet carpet shell Venerupis corrugata (Gmelin, 1791) in a recirculating aquaculture system

The pullet carpet shell Venerupis corrugata is an economically valuable species in several European countries, however, nowadays stocks are under high fishing pressure. Hatchery production of juveniles for release is a major contributor to strengthen the stock and consequently improve the sustainability of the natural stocks. This study aimed to determine the feasibility of rearing V. corrugata larvae with different larval densities (10, 40 and 200 larvae per mL) in a recirculating aquaculture system (RAS), compared with the traditional larval rearing methodology (Batch). The mean survival, growth and metamorphic rate of V. corrugata larvae in RAS was higher (11.1%; 71.3 μm; 21.6% respectively) than in the Batch system, in all tested densities. The larval growth was not affected by the initial density until 40 larvae per mL, however, 200 larvae per mL decreased the larval growth in length nearly 54 μm. The larval rearing time was shortened in 2 days in the RAS system. The physical, chemical and microbiologic parameters suggested that the tested densities were not excessive to disturb the biofilter stability of RAS. The V. corrugata larval rearing performed at high larval stocking densities in RAS system present a reduction in the operating costs to produce this species.     

New defensins from hard and soft ticks: Similarities,differences, and phylogenetic analyses

Despite the importance of ticks as vectors of disease very little is known about their immune system. Antimicrobial peptides, including defensins (phylogenetically ancient antibacterial peptides) are major components of innate immunity in ticks that have been shown to provide protection against gram-negative and gram-positive bacteria, fungi, viruses and protozoan parasites. With the aim of studying the evolution of the genes involved in tick defense, we identified the preprodefensin genes from four Ornithodoros tick species (O. papillipes: isoforms A, B, and D; O. tartakovskyi and O. puertoricensis: isoforms A and B; O. rostratus: isoform A) and from two Dermacentor tick species (D. reticulatus and D. marginatus: one isoform) not previously described. Phylogenetic analyses revealed that Ornithodoros defensin isoforms (A, B, C, and D) form 4 separate clades, while hard tick defensins are divided into several branches based on particular tick species.     

The effect of the combination of acids and tannin in diet on the performance and selected biochemical,haematological and antioxidant enzyme parameters in grower pigs

Background

The abolition of in-feed antibiotics or chemotherapeutics as growth promoters have stimulated the swine industry to look for alternatives such as organic acids, botanicals, probiotics and tannin. The objective of the present study was to compare the effects of a combination of acids and tannin with diet with organic acids and diet without growth promoters on the growth performance and selected biochemical, haematological and antioxidant enzyme parameters in grower pigs. Tannin is more natural and cheaper but possibly with the same effectiveness as organic acids with regard to growth performance.

Methods

Thirty-six 7 week old grower pigs, divided into three equal groups, were used in a three week feeding trial. Group I was fed basal diet, group II basal diet with added organic acids and group III basal diet with added organic and inorganic acids and tannin. Pigs were weighed before and after feeding and observed daily. Blood was collected before and after the feeding trial for the determination of selected biochemical, haematological and antioxidant enzyme parameters. One-way ANOVA was used to assess any diet related changes of all the parameters. Paired t-test was used to evaluate changes of blood parameters individually in each group of growers before and after feeding.

Results

No clinical health problems related to diet were noted during the three week feeding trial. The average daily gain (ADG) and selected blood parameters were not affected by the addition to basal diet of either acids and tannin or of organic acids alone. Selected blood parameters remained within the reference range before and after the feeding trial, with the exception of total serum proteins that were below the lower value of reference range at both times. The significant changes (paired t-test) observed in individual groups before and after the feeding trial are related to the growth of pigs.

Conclusion

Diet with acids and tannin did not improve the growth performance of grower pigs but had no deleterious effects on selected blood parameters. The possibility of beneficial effects of adding acids and tannin in diets on growth performance over a longer period, however, could not be excluded.