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Radionuclide concentrations in wharf roaches inhabiting coastal areas of Honshu, Japan, were investigated in October 2011 and June 2012. Relative high concentrations of 110mAg (2.1–127 Bq kg-wet−1), 134Cs (2.6–61 Bq kg-wet−1), and 137Cs (3.5–92 Bq kg-wet−1) were detected in specimens from the eastern Honshu areas. Significantly lower 137Cs concentrations (0.7–1.6 Bq kg-wet−1) were detected in specimens from western and northern Honshu. The decay-corrected 137Cs concentration was significantly inversely correlated with the distance from the Fukushima Dai-ichi Nuclear Power Plant. Thus, wharf roach may serve as a good bioindicator for monitoring radioactive contamination of its habitats.

The abundance of sulphate-reducing bacteria (SRB) was investigated in the coastal marine sediments along the coast of Japan and South Korea. Sediment samples were collected from fish and shellfish farms between 2006 and 2008. As non-fish farming reference sites, sediments were also collected from highly eutrophic bays, a highly sulphidogenic saline lake, and the deep sea. A quantitative real-time PCR analysis that targeted the gene coding for a portion of the α-subunit of dissimilatory sulphite reductase (dsrA) was performed to assess the abundance of the SRB in the sediments. Between 2.8 × 107 and 2.5 × 109 copies of the dsrA gene per gram dry sediment were detected. There was no relationship between dsrA gene copy number and total bacterial count in the sediments, whereas organic matter contents (particulate organic carbon and nitrogen, ignition loss and chemical oxygen demand) and acid-volatile sulphide contents were significantly correlated with the dsrA copy number. The data presented demonstrate that organic enrichment of sediment may influence the abundance of SRB communities in coastal marine sediments and that the cell density of SRB may be used as a biological indicator for assessing pollution levels in sediments of marine fish farms.

The spionid polychaete Paraprionospio pinnata (Ehlers 1901) has been widely reported from Korean waters. We examined some specimens belonging to the genus Paraprionospio that had been collected from Korean waters, and identified them as Paraprionospio coora Wilson, 1990, Paraprionospio cordifolia Yokoyama, 2007 and Paraprionospio patiens Yokoyama, 2007, which are new to the fauna of Korea. The present study suggests misidentification of the specimens that have been previously reported as P. pinnata from Korean waters.

Potential microbial extracellular leucine-aminopeptidase (LAP) and β-glucosidase (βGlc) activity in the sediments of a red sea-bream (Pagrus major) aquaculture area were measured. Temporal variations in these enzymatic activities were low and stable from December 1999 to April 2000. They rose but fluctuated widely from May to November 2000. LAP activity in the sediments ranged from 334 to 4461 nmol/g per h in the 0–1-cm layer and from 106 to 258 nmol/g per h in the 4–5-cm layer. βGlc activity ranged from 221 to 4121 nmol/g per h in the 0–1-cm layer and from 18 to 238 nmol/g per h in the 4–5-cm layer. These values were higher than others reported and the organic matter load from the fish farms appeared to promote these enzymatic activities, although the relationship was not linear. The ratio of LAP to βGlc was smaller than other reported values in marine sediments or in water samples from the same aquaculture area, suggesting that not only quantitatively but qualitatively an aspect of organic matter degradation in the sediment might be changed by the heavy supply of organic materials from fish farms.

Grab samples of the smaller macrobenthos (>1 mm