The complete mitochondrial genome of the burrowing ghost shrimp, Nihonotrypaea harmandi (Bouvier, 1901), (Crustacea, Decapoda, Axiidea, Callianassidae) - a validation of the genus and species classifications.

The complete mitochondrial genome of the burrowing ghost shrimp Nihonotrypaea harmandi was reconstructed using the Illumina HiSeq platform. The genome was 15,272 bp in length made up of 37 mitochondrial genes (13 CDSs, 22 tRNAs, and 2 rRNAs) in the same order as other Nihonotrypaea species. Phylogenetic analyses suggested that Nihonotrypaea is a valid genus, and that N. harmandi can be phylogenetically marginally separated from N. japonica, though some authors considered the former as a synonym of the latter.

Dynamics of bacterial community structure on intertidal sandflat inhabited by the ghost shrimp Nihonotrypaea harmandi (Decapoda: Axiidea: Callianassidae) in Tomioka Bay, Amakusa, Japan.

Callianassid (ghost) shrimp has been claimed as an ecosystem engineer, as it is one of the most powerful bioturbating macrobenthos in intertidal sandflats. However, our knowledge about the relationship between areal distribution of bottom-dwelling ghost shrimps and dynamics of sediment microbial community structure remains obscured. We used automated ribosomal intergenic spacer analysis (ARISA) to reveal the bacterial community dynamics in the sediment of intertidal sandflat of Tomioka Bay, Kyushu, Japan, which is predominantly inhabited by a burrow-dwelling callianassid shrimp Nihonotrypaea harmandi. We found that the bacterial community structures of high and middle shrimp population areas were significantly differentiated from those of low population area (ANOSIM, R=0.10-0.18, p<0.01), while the former two areas were statistically indistinguishable (ANOSIM, R=-0.015, p>0.1). These results illustrated the potential importance of shrimp population density as a key factor in shaping the bacterial community structure and interpreting their dynamics in the sandflat. Furthermore, greater similarity between burrow and non-burrow communities was found in samples taken in autumn through winter than in those in summer (one-way ANOVA, p<0.05), whereas the phylotype richness was not simply differentiated by seasons. These results suggest not only that environmental variables including water temperature and salinity of the water column overlying the sandflat could exert notable impacts on the sediment bacterial community dynamics, but that the bio-irrigation and mixing by the ghost shrimp in permeable sandflat would strongly homogenize sediment particles, enhance solute transport surrounding the burrow and ambient subsurface substrate, and therefore reduce spatial differentiation of the bacterial community structure between the two sites. A comparison between present and previous studies of axiidean (former taxonomic group name, thalassinidean) ghost shrimps provides us with a comprehensive understanding of the shrimps' impacts on bacterial community dynamics, highlighting the importance of sediment permeability, a characteristic determined by the type of sediment, as a key controlling factor to shape spatial heterogeneity of bacterial community structure around burrow.

Larval stages of the bluefin tuna blood fluke Cardicola opisthorchis (Trematoda: Aporocotylidae) found from Terebella sp. (Polychaeta: Terebellidae).

We found aporocotylid larval stages (sporocysts and cercariae) from five individuals of terebellid polychaete Terebella sp., which were collected from seabed substrate and ropes and floats attached to tuna cages in a tuna farm on the coast of Tsushima Island, Nagasaki, Japan. Nucleotide sequences of the regions of internal transcribed spacer 2 ribosomal DNA and 28S ribosomal DNA from these larval stages were 100% identical to those of Cardicola opisthorchis registered in GenBank. C. opisthorchis is a pathogen causing blood fluke infection of Pacific bluefin tuna Thunnus orientalis, which is considered to have a significant impact on the Japanese Pacific bluefin tuna aquaculture industry. This is the first description of the intermediate host of C. opisthorchis. This indicates that the life cycle of C. opisthorchis is completed within tuna farms in this area.