Two specimens of an unknown jellyfish species were collected in Bat Gallim and Beit Yannai, on the Mediterranean coast of Israel, in June and July 2010. Morphological characters identified it as a cepheid (Cnidaria, Scyphozoa, Rhizostomeae). However, the specimens showed remarkable differences from other cepheid genera; unlike Cephea and Netrostoma it lacks warts or knobs centrally on the exumbrella and filaments on oral disk and between mouths, and it differs from Cotylorhiza in its proximally loose anastomosed radial canals and in lacking stalked suckers and filaments on the moutharms. We thus describe it herein as Marivagia stellata gen. et sp. nov. We also present the results of molecular analyses based on mitochondrial cytochrome oxidase I (COI) and 28S ribosomal DNA, which support its placement among the Cepheidae and also provide its barcode signature. This new find is the fourth introduced scyphozoan species recorded in the Mediterranean. The presence of a sexually mature specimen collected as far back as 2006, and the occurrence of the species this summer at sites nearly 90 kms apart, indicate the existence of an established population.
Within the framework of a larger project aimed to assess the potential of second generation hybrid striped bass for German aquaculture the genotypic segregation of five microsatellite loci was analysed in two progeny lots (n = 74 and 76, respectively). There was no consistent correlation between microsatellite genotypes and phenotypic category (white bass, hybrid, or striped bass). None of the individuals expressed neither only white bass nor only striped bass genotypes at all five loci. On the other hand, only hybrid genotypes at all five loci were detected in three individuals of lot 1 and four individuals of lot 2. Single loci tests for conformity of microsatellite genotypic segregation with Mendelian rules revealed significant deviations (P \ 0.05) in four cases for lot 1 and in three cases for lot 2. If pooled over all five loci, both lots displayed highly significant deviations (P \ 0.01) with an excess of hybrid genotypes and a deficiency of white bass genotypes. It is concluded that stabilizing selection performed on hybrid genotypes might be a suitable approach for practical aquaculture in Europe if the goal is to become independent of first generation hybrid fry supply and/or if establishing domesticated brood stocks of both parental species is impossible. However, more detailed studies on the characteristics and performance of multiple hybrid generations are needed.
Infections of common carp Cyprinus carpio and koi, its coloured morphotypes, with the cyprinid herpesvirus 3 (CyHV-3) can induce severe clinical signs and increased mortality in affected stocks. This may significantly challenge the economic basis of carp farming in Central Europe. To limit virus spread in carp farms, effective disinfection measures for ponds stocked with infected populations are required. In the traditional European pond aquaculture of carp, draining and liming of ponds with quicklime (CaO) up to pH 12 is a well-established disinfection measure against various pathogens. The present field study investigated whether these measures are sufficient for the inactivation of CyHV-3 infectivity in carp ponds. After draining and liming, the ponds were stocked with carp fry from a CyHV-3-negative stock, and 2 ponds were examined for the presence of CyHV-3-specific DNA sequences during the growth period of the carp and in the harvested stock. Wild fish (from the ponds, and feeder and drainage canals) and water samples (from the ponds) were also examined for CyHV-3-specific DNA sequences; and naïve carp were cohabited with wild fish, or exposed to the pondwater samples, to test for the presence of infectious virus. All examined samples remained negative for CyHV-3 throughout the study. This indicates that draining and liming with quicklime can be a suitable disinfection measure for ponds after a CyHV-3 outbreak in carp aquaculture.
Die Welsaufzucht ist in der Aquakultur eine Alternative zur Karpfenproduktion. Für den Europäischen Wels (Silurus glanis) liegen keine oder sehr wenige Angaben über den Bedarf an n‐3‐ und n‐6‐Fettsäuren sowie über den Fettgehalt und den Anteil von Polyensäuren im Fischfleisch bei Pelletverfütterung vor. Unsere Untersuchungen zeigen, daß der Fettgehalt durch das Futter beeinflußt wird. Der Fettgehalt im Fischfleisch war nach Pelletfütterung annähernd 4mal höher als bei Naturnahrung. Im Vergleich zum Karpfen sollte das Welsfutter reich an polyungesättigten n‐3‐Fettsäuren sein. Dies spiegelt sich auch im Fischfleisch wieder. Die Konzentration an n‐3‐Fettsäuren betrug im Mittel 2,9 g/100 g Frischfleisch. Dieser Gehalt entspricht dem von Seefischen, wie Hering und Makrele, die für klinische Studien verwendet wurden.
Catfish rearing is an alternative to carp production in aquacuture. There is no or little data available neither on the n‐3 and n‐6 polyunsaturated fatty acid requirements for European catfish (Silurus glanis), nor on the content of these fatty acids and the proportion of fat in fish meat of feeding pellets. Our investigations show, that the fat content can be influenced by the feed. The fat content in the fish meat is nearly four times higher after pellet feeding, when compared with the natural feed. In comparison to carp, catfish feed should be rich in n‐3 polyunsaturated fatty acids. This is reflected in the composition of fish meat. The concentration of n‐3 polyunsaturated fatty acids was on an average of 2.9 grams per 100 grams fresh meat. This content is similar to that of seafish such as herring and mackerel, which are used for clinical studies.
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