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The article focuses on a study that examined the phylogenetic relationship of Perkinsus olseni originating from the Ebro Delta in Spain with other Perkinsus species using two molecular markers, the nontranscribed spacer (NTS) region and the internal transcribed spacer (ITS) region. The markers used in the study were sequenced from prezoosporangia of Perkinsus species originating from Manila clam, Ruditapes philippinarum, from the Ebro Delta. An analysis of the markers indicated the species identity of the pathogen species found in the clam.

Larvae of two Mediterranean Sparidae species, Sparus aurata and Dentex dentex, were used to test the efficacy of a peroxide-based product (Ox-Aquaculture©) on the reduction in bacterial load in larval rearing water and its effects on larval survival. Eleven-day-old S. aurata larvae and 15-day-old D. dentex larvae were exposed to different concentrations of Ox-Aquaculture© (50, 100 and 200 mg L−1, and 20 and 50 mg L−1 respectively) for 1 h. Results indicated that 50 and 20 mg L−1 were the most effective concentrations for the reduction in bacterial load (at least one order of magnitude) after 1 h treatment, without affecting larval survival and/or vitality in 11 dph S. aurata and 15 dph D. dentex larvae respectively. Ox-Aquaculture© concentrations of 200 and 50 mg L−1 during 1 h affected negatively final survival rate of the larvae of S. aurata and D. dentex respectively. [ABSTRACT FROM AUTHOR]

Reduction of the bacterial load in live prey is paramount to achieving efficient microbiological control during fish larval rearing. Several methods have been tested using physical and chemical disinfection procedures. Nevertheless, chemicals are difficult to deal with because of the frequent problems encountered when disposing of their residual products and because of the sensitivity of the live prey. Hydrogen peroxide is a good disinfectant that has been used for a long time in other fields of research and decomposes in non-toxic products. However, it has not been applied for disinfection in aquaculture until recent years. The effects of a hydrogen peroxide-based product, Ox-Aquaculture©, on rotifers and Artemia nauplii survival and on their associated microbial population have been tested in the present study, a disinfection protocol is proposed, and its effects on live prey fatty acids composition after enrichment were checked. More than 80% survival and a 90% reduction of total heterotrophic bacteria and Vibrionaceae were obtained in rotifers exposed for 15 min to 40 mg L-1 of the product. In the case of Artemia nauplii, 90% survival and 945% reduction of heterotrophic bacteria were obtained after 5 min exposure to 8000 mg L-1 with a further 82.8% reduction of Vibrionaceae. No differences in the fatty acid composition of the live prey were detected after disinfection with hydrogen peroxide. No oxidation of polyunsaturated fatty acids was observed. A short time exposure and easy removal of the product from the treated live prey make hydrogen peroxide an interesting chemical for industrial application. [ABSTRACT FROM AUTHOR]

Reduction of the bacterial load in live prey is paramount to achieving efficient microbiological control during fish larval rearing. Several methods have been tested using physical and chemical disinfection procedures. Nevertheless, chemicals are difficult to deal with because of the frequent problems encountered when disposing of their residual products and because of the sensitivity of the live prey. Hydrogen peroxide is a good disinfectant that has been used for a long time in other fields of research and decomposes in non-toxic products. However, it has not been applied for disinfection in aquaculture until recent years. The effects of a hydrogen peroxide-based product, Ox-Aquaculture©, on rotifers and Artemia nauplii survival and on their associated microbial population have been tested in the present study, a disinfection protocol is proposed, and its effects on live prey fatty acids composition after enrichment were checked. More than 80% survival and a 90% reduction of total heterotrophic bacteria and Vibrionaceae were obtained in rotifers exposed for 15 min to 40 mg L-1 of the product. In the case of Artemia nauplii, 90% survival and 945% reduction of heterotrophic bacteria were obtained after 5 min exposure to 8000 mg L-1 with a further 82.8% reduction of Vibrionaceae. No differences in the fatty acid composition of the live prey were detected after disinfection with hydrogen peroxide. No oxidation of polyunsaturated fatty acids was observed. A short time exposure and easy removal of the product from the treated live prey make hydrogen peroxide an interesting chemical for industrial application. [ABSTRACT FROM AUTHOR]