Two hundred and seven species of fish, mostly Australian marine fish, were sequenced (barcoded) for a 655 bp region of the mitochondrial cytochrome oxidase subunit I gene (cox1). Most species were represented by multiple specimens, and 754 sequences were generated. The GC content of the 143 species of teleosts was higher than the 61 species of sharks and rays (47.1% versus 42.2%), largely due to a higher GC content of codon position 3 in the former (41.1% versus 29.9%). Rays had higher GC than sharks (44.7% versus 41.0%), again largely due to higher GC in the 3rd codon position in the former (36.3% versus 26.8%). Average within-species, genus, family, order and class Kimura two parameter (K2P) distances were 0.39%, 9.93%, 15.46%, 22.18% and 23.27%, respectively. All species could be differentiated by their cox1 sequence, although single individuals of each of two species had haplotypes characteristic of a congener. Although DNA barcoding aims to develop species identification systems, some phylogenetic signal was apparent in the data. In the neighbour-joining tree for all 754 sequences, four major clusters were apparent: chimaerids, rays, sharks and teleosts. Species within genera invariably clustered, and generally so did genera within families. Three taxonomic groups-dogfishes of the genus Squalus, flatheads of the family Platycephalidae, and tunas of the genus Thunnus-were examined more closely. The clades revealed after bootstrapping generally corresponded well with expectations. Individuals from operational taxonomic units designated as Squalus species B through F formed individual clades, supporting morphological evidence for each of these being separate species. We conclude that cox1 sequencing, or 'barcoding', can be used to identify fish species.

Four freshwater Antarctic lakes were examined for the presence of pgalactosidase-producing bacteria using mineral medium enrichments and lactose. Enrichments from only one of the lakes produced growth and two strains were isolated that were very similar in phenotype and fatty acid profile, and shared considerable homology in their DNA (DNA-DNA hybridization = 9327 YO). The strains were psychrotrophic with theoretical T,,,,,, Tmin and To,, of 30-31, -7 O and 26 "C, respectively. The P-galactosidase in cell extracts had an optimal activity at 39 "C. The strains were Gram-negative rods, showed gliding motility, contained branched and hydroxy fatty acids, and menaquinone 6 as the major respiratory quinone. The strains did not form microcysts and utilized lactose while using ammonium ions as a source of nitrogen, and a range of other sugars. The G+C content of the DNA was 34 mol%. Phylogenetic analysis of one of the strains, by comparison of 165 rDNA sequences, showed that it was most similar, but not identical to, Flavobacterium columnare and [Sporocytophaga] cauliformis '. Both species could be differentiated phenotypically from the Antarctic isolates. DNA-DNA hybridization of the Antarctic isolate with six different members of the Flavobacterium 165 rDNA cluster showed no strain with greater than 18% relatedness. The nearest type species to the Antarctic isolate in the phylogenetic analysis was Flavobacterium aquatile. The name Flavobacterium hibernum is proposed for the Antarctic strains, and the type strain is ATCC 51468T (= ACAM 376T).Keywords: Flavobacterium hibernum, psychrotroph, P-galactosidase, Antarctica INTRODUCTIONMany humans are intolerant to lactose in their diet and as a result are unable to consume unfermented dairy products without considerable discomfort. One technological approach to solving this problem is to use bgalactosidase in the processing of dairy foods. However, the optimal temperatures for hydrolysis of lactose by P-galactosidases range between 30 and 40 OC, which is also the ideal temperature range for the growth of mesophiles that contaminate and spoil dairy products (Gounot, 1991). Hydrolysis of lactose at low temperatures may be a viable option if a psychrophile can be isolated that produces an efficient low-temperature b-galactosidase (Gounot, 199 1).As part of an ongoing study on the microbial diversity of Antarctic ecosystems, and due to the possible benefits arising from the isolation of psychrophilic j?-galactosidase-producing strains, we targeted lactoseutilizing strains from a number of freshwater Antarctic lakes for enrichment and isolation. A taxonomic study of the isolates was undertaken and the work is herein described. Isolation of bacterial strains. Four freshwater Antarctic lakes [conductivity (pS cm-') and pH given in parentheses after each name] : Druzhby Lake (29,7*2), Crooked Lake (26,7.1), Pauk Lake (118, 7-0) and Lichen Lake (73, 7.3), were sampled for lactose-utilizing bacteria. Each lake was sampled twice, at the same hour from sample points within 10 m of each...

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The level of genetic diversity in a cultured Atlantic salmon (Salmo salar) population from Tasmania, Australia was examined at 11 microsatellite loci and compared with that in its progenitor population from the River Philip in Nova Scotia, Canada. The reference progenitor population consisted of archived scales collected from wild River Philip salmon in 1971 and 1972, not long after salmon from this river were imported into Australia in the mid‐1960s. The Tasmanian hatchery stock had a significant reduction in the mean number of alleles (31–43%) and mean allelic richness (28–39%) across all microsatellite loci compared with the wild Canadian population. Mean heterozygosity levels remained unchanged. Estimates of per‐generation effective population sizes for the Tasmanian population, based on allele frequency temporal variance with the wild progenitor population, ranged from 102–207 individuals and reflected hatchery records.

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