Reconstruction of paleoenvironment using calcium carbonate coral skeletons and bivalve shells: Coral skeletons and bivalve shells consist of calcium carbonate minerals and contain records of ambient information at the time they lived. Fine chemical analyses of these skeletons and shells can reveal various information such as water-temperature and aqueous chemistry. / Higi-precision paleoenvironmental reconstruction using terrestrial cismogenic nuclides: Terrestrial cosmogenic nuclides (TCNs; ¹⁰Be, ²⁶Al, and ³⁶Cl etc.) are produced with the interaction between the target atoms and secondary cosmic rays in the atmosphere or the rock. We can obtain important informations on the mechanisms of the global climate changes by concentrations of TCNs in the atmosphere or the rock.

Census of Marine Zooplankton (CMarZ): a global research on zooplankton biodiversity
The ocean occupies more than 95% of the biosphere on Earth. There is a wealth of diversity in the ocean life, but we only know a small potion of it. The Census of Marine Life (CoML) is an international project in the term 2000-2010, aiming at elucidating the past and present of marine life.

Independent evolution of the specialized pharyngeal jaw apparatus in labroid fishes
The evolution of complex organs is a source of controversy because they require the contribution of many adaptations to function properly. But, it is well known that complex organs with similar function repeatedly evolved in the history of living things.

Deepest living fishes recorded for the first time in the world.
Living fishes of extreme environment of hadal bottom in the Japan trench are recorded for the first time in the world. The Hadal Environmental Science/Education Program (HADEEP) Research team has succeeded in recording video footage of a number of living fishes at depth of 7703 m south of the Japan trench, off Boso-Ibaraki, in the NW-Pacific using the 12,000 m rated hadal lander launched from the R/V Hakuho-maru. It was commonly believed until now that these fish did not exist at such a great depth.

Searching for new hormones that govern adaptation to hypertonic marine environment in teleost fishs
Hypertonic marine environment is even more desiccative than terrestrial environment as exemplified by the frog soaked in seawater (SW). The frog loses body weight more quickly in SW than on dry land because of three-fold higher osmotic pressure of SW than body fluids. Marine teleost fish, which have plasma osmolality one third that of SW just like the frog, lose water from the thin epithelial surfaces of the gills that have 20-fold wider surface area than the skin. Then, how do teleost fish survive in such a desiccative environment and what factors are involved in this regulation?

Genetic characteristics of recently discovered populations of the tideland snail Cerithidea djadjariensis
Recently, northward range expansion has been reported for various species and suspects the influences of global warming. As the rates of expansion are different from species to species, changes of species composition of ecosystems may destroy networks of interspecidfic interactions, which have formed for a long time, and inflict irreversible damage on ecosystem structures.

A new discovery about the Japanese conger eel -Where do they spawn?-
Similar to the Japanese eel, Anguilla japonica, it has long been mysterious where in the ocean the common Japanese conger eels, Conger myriaster, go to spawn. It had been thought to possibly spawn at the edge of the continental shelf of the East China Sea (Takai 1959), but only large sized larvae (called leptocephali) had ever been collected there (Kurogi et al. 2002).

Strong tidal mixing around the Kuril Straits and bidecadal variability in the Northwestern Pacific and climate synchronized with 18.6-year period nodal tidal cycle
North Pacific marine ecosystem including tuna and small pelagic fish as sardine and anchovy is known to be related with inter-decadal ocean-climate variability. However, multi-decadal time-scale ocean-climate variability and mechanism remain unclear and thus unpredictable.

A high-resolution 3D seismic reflection imaging of the Nankai Trough off Kii Peninsula, SW Japan
Historically, large earthquakes along subduction zones have occurred with a recurrence interval of 100-200 years along the Nankai Trough margin where the Philippine Sea Plate subducts beneath the Eurasian Plate to the NNW. In late 2007, the IODP (Integrated Ocean Drilling Program) NanTroSEIZE (Nankai Trough Seismogenic Zone Experiment) project began drilling into the seismogenic portion of the megathrust along which the 1944 Tonankai earthquake (M = 8.1) has occurred off the Kii Peninsula, southwest Japan.

Bio-logging reveals behavioral ecology of seabirds
Recent advances in animal-borne recorders have provided many exciting insights into the foraging ecology and behavioral physiology of top marine predators, particularly diving species. However, precisely how these predators catch their prey underwater, their foraging habitats, their prey species, and the amount of prey they capture remain largely unknown. We are developing new devices and new methodologies to analyze time-series data to address these questions.