Recent advances in our understanding of the biodiversity of copepods in Japanese waters are briefly reviewed. It is noteworthy that the two new species of Platycopioida found in Japan are the first record of this order from the Indo-Pacific. Taxonomic revisions of calanoids in Japanese waters have continued based on both morphological and molecular data. Molecular analyses have revealed the presence of cryptic/sibling species in a common species and of intraspecific variations. Complete mitochondrial DNA sequences from copepods have been analyzed for Tigriopus japonicus, which suggest that copepods are genetically 'eccentric.' Molecular tools have helped to clarify the phylogenetic relationships of highly modified symbiotic copepods. Population dynamics, life cycles, and distributions of planktonic copepods have been thoroughly investigated in coastal and oceanic waters. These studies highlighted the influence of the Oyashio/Kuroshio currents on the coast, the high mortality of eggs from predation, adaptive responses to phytoplankton blooms, and niche partitioning by habitat and food. Deep-sea calanoids are highly diverse and specialized for detritivory and carnivory. East Asian planktonic copepods have been introduced to America and Europe via ballast water, although Japan not yet received any alien planktonic copepods. In contrast, parasitic copepods have been introduced to Japan via aquaculture. The life cycle of commercially important sea lice was clarified. Because copepods are one of the most abundant metazoans on Earth, more biological but also biomimetic information should be accumulated.
A first trial to recognize gelatinous zooplankton using an immunochemical method was carried out. Polyclonal antibodies (rabbit IgG) raised against three cnidarians and four pelagic tunicates were purified and tested for their specificity against various sympatric zooplankton and micronekton. While antibodies to cnidarians were species-specific or at least distinguishable by means of the patterns of the bands appearing, antibodies to the pelagic tunicates cross-reacted with the antigen from the other tunicate species although these did not cross-react with other animal taxa. These results suggest that the present cnidarian antibodies can be applied to the predator identification at the species level. Antibodies to pelagic tunicates would also be effective tools for basic scanning at higher taxonomic levels, i.e. pelagic tunicates or other animals. The antibodies were applied to the identification of the ‘barrel’ of Phronima , indicating that the ‘barrels’ originated from tunicates but not from cnidarians. The present study indicates that the immunochemical method using polyclonal antibodies is a powerful tool for the detection of gelatinous zooplankton.
This paper describes an automated cable-laying system that can automatically pay out a submarine cable on the seafloor while keeping balance with the ground speed. We have installed DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) at Kumanonada and a ROV (Remotely Operated Vehicle) was successfully used to lay the cables which connect observatories to the nodes of the DONET. However, such a cable-laying work was regarded as one of the hardest works since it takes approximately 10 hours (about 10km distance) and is manually carried out by a ROV operator(s). The automated cable-laying system can contribute to reduce the physical and mental burdens on the ROV operator and speed up the construction of DONET2 (the second phase of DONET). In this paper, the components and cable-laying control strategies are described and some experimental results are presented. In addition, we report on the first mission to connect the borehole observatory C0002 to the Node D of the DONET. This achievement has made it possible to receive the data of the borehole observatory in real-time. The paid out cable is 8470m and the travelled distance is approximately 8000m.
