Japanese Pacific Coast Research Articles

A New Species of Acoela Possessing a Middorsal Appendage with a Possible Sensory Function.

Acoels, belonging to Xenacoelomorpha, are small worms with a relatively simple body plan and are considered a critical clade for understanding the evolution of bilaterians. Despite acoels' importance, however, many undiscovered species are predicted to be present worldwide. Here, we describe a new marine acoel species, Amphiscolops oni sp. nov., based on materials collected from the intertidal and subtidal zones of rocky shores at several localities along the Japanese Pacific coast. The new species is approximately 3 mm long and shows typical characteristics of the family Convolutidae, such as the presence of eyespots, symbiosis with algae, position of the gonopores, morphology of the bursal nozzles, lack of central singlet microtubules in the axonemes of spermatozoa, and funnel-like posture of the anterior end. Based on morphology and the results of molecular phylogenetic analyses, we assign this species to the genus Amphiscolops. Interestingly, these worms show unique behaviors such as swimming by flapping the lateral sides and actively capturing prey by swinging the anterior funnel. Furthermore, they possess a dorsal appendage-a characteristic previously unreported in Xenacoelomorpha-representing an evolutionary novelty acquired by this species.

Hexacoral-crinoid associations from the modern mesophotic zone: Ecological analogues for Palaeozoic associations

Coral-crinoid associations, where a coral overgrew a crinoid's stem, were among the very common Palaeozoic benthic associations, lasting until the end of the Palaeozoic. Many skeletal overgrowths described so far document syn vivo relationships. This type of interaction is unknown from later, Meso- and Cenozoic deposits, and to date has been unknown from recent seas. Here we analysed two individuals of the crinoid Metacrinus rotundus collected from mesophotic depths off the Japanese Pacific coast, overgrown by a single zoantharian polyp of Abyssoanthus sp. (Anthozoa: Hexacorallia: Zoantharia: Abyssoanthidae), and by some sea anemones identified as Metridioidea sp. indet. (Hexacorallia: Actiniaria). These azooxanthellate hexacorals do not possess skeletons, and were located below the host's feeding fan. Our microtomography examinations showed that the anemones did not modify the host's columnals. These specimens offer a good ecological analogue to similar associations of rugose, Cladochonus-like and tabulate corals known from the Palaeozoic. While in our specimens competition for food between hexacorals and crinoid likely does not occur, such interactions are possible. Both zoantharians and sea anemones show similar corallite/oral disc diameters to rugose corals and Cladochonus-like cnidarians that overgrew crinoids in the Palaeozoic, and therefore they probably obtained similar sizes of food particles. In environments with low relief seafloors these hexacorals benefited from their elevated position, and therefore stronger feeding currents. As both Actiniaria and Zoantharia have their phylogenetic roots deep in the Palaeozoic, and coral-crinoid associations are common among Palaeozoic tabulate and rugose corals, we speculate that also Palaeozoic non-skeletal corals, inferred from molecular studies, may have also developed this strategy of settling on crinoids, and therefore occupying similar ecological niches to these hexacorals described here. This report documents that coral-crinoid associations, characteristic of Palaeozoic benthic communities, and thought to have disappeared by the end of Permian, exist in modern seas.

<i>Styela plicata</i> (Lesueur, 1823) (Urochordata: Ascidiacea) from Ofunato Bay, Iwate Prefecture; first cool-temperate records from the Japanese Pacific coast

<i>Styela plicata</i> (Lesueur, 1823) (Urochordata: Ascidiacea) from Ofunato Bay, Iwate Prefecture; first cool-temperate records from the Japanese Pacific coast

MON-336 LONGITUDINAL ANALYIS OF KIDNEY FUNCTION AND POSSIBLE FACTORS INVOLVED AFTER THE GREAT EAST JAPAN EARTHQUAKE AMONG RESIDENTS NEAR THE FUKUSHIMA DAIICHI NUCLEAR POWER PLANT

In March 2011, the Great East Japan Earthquake and subsequent tsunami seriously damaged the northeast Japanese Pacific coast, including a level 7 accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP). Thousands of residents of Futaba District (where FDNPP is located) evacuated because of possible radioactive contamination. Seven years after the accident, evacuated residents are coming back to Futaba District due to the decreased exposure to radioactivity. The long-term effects of the Great East Japan Earthquake and the FDNPP accident on the kidney function of residents of Futaba District remained unknown. We performed yearly medical examinations of Futaba District residents aged ≥40 years from 2011 to 2016. Approximately 15,000 residents underwent the medical examination every year. Of these, 4,712 had evacuated the district after the Earthquake. The prevalence of hypertension defined as systolic blood pressure >140 mmHg was more than 40% in the days right after the Earthquake, and the prevalence gradually decreased to less than 30% in 2014. The prevalence thereafter increased again over the next 2 years. The prevalence of glycosuria showed a pattern similar to that of hypertension. The prevalence of residents with HbA1c >6.0% and the mean uric acid level increased throughout the 6-year examination. The prevalence of proteinuria remained unchanged, while that of hematuria slightly decreased. The mean creatine and estimated glomerular filtration rate values showed no specific alteration tendency, but the prevalence of chronic kidney disease (CKD) stage G3 or worse kept increasing throughout the 6-year examination. Interestingly, the individuals who evacuated were associated with a significantly higher risk of a new onset of CKD stage G3 or worse compared to the residents who never evacuated, even after the adjustment of background factors. Various factors including psychological stress by the disaster itself, psychological stress due to life as an evacuee, and the decreased amount of outdoor activity were likely to be associated with the changes in the health condition of the inhabitants of Futaba District. Those factors are also likely to have slight but significant influences on kidney function. Our analyses identified no factors that appeared to be directly affected by radiation exposure

Numerical modelling of 137Cs content in the pelagic species of the Japanese Pacific coast following the Fukushima Dai-ichi Nuclear Power Plant accident using a size-structured food-web model.

As result of the great east Japan earthquake on March 2011 and the damages of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), huge amount of radionuclides, especially 137Cs, were released to the Japanese Pacific coast. By consequence, several marine species have been contaminated by direct uptake of radionuclides from seawater or through feeding on contaminated preys. In the present study we propose a novel radioecological modelling approach aiming to simulate the radionuclides transfer to pelagic marine species by giving to the organism body-size a key role in the model. We applied the model to estimate the 137Cs content in 14 commercially important species of the North-Western Pacific Ocean after the FDNPP accident. Firstly, we validated the model and evaluated its performance using various observed field data, and we demonstrated the importance of using such modelling approach in radioecological studies. Afterwards, we estimated some radioecological metrics, such as the maximum activity concentration, its corresponding time and the ecological half-life, which are important in assessment of the previous, current and future contamination levels of the studied species. Finally, we estimated the time duration required for each species to reach the pre-accident 137Cs activity concentrations. The results showed that the contamination levels in the planktivorous species have generally reached the pre-accident levels since about 5 years after the accident (since 2016). While in the case of the higher trophic level species, although the activity concentrations are much lower than the regulatory limit for radiocesium in seafood in Japan (100 Bq kg-1), these species still require another 6–14 years (2018–2026) to reach the pre-accident levels.

A parameter quantifying radiation damping of bay oscillations excited by incident tsunamis

The transient response of a bay with a narrow mouth to incident tsunamis is interpreted as the convolution of the input signal with the impulse response obtained by an inverse Fourier transform of the response curve of the oscillatory system with one degree of freedom. The rate of radiation damping associated with energy escaping seaward through the bay mouth is expressed in terms of the quality factor Q, which determines the decaying envelope of the impulse response. The value of Q of the resonant peak is approximated by the ratio of the resonant frequency ω0 to the bandwidth between frequencies at which the power spectral density of sea level within the bay drops to half of the peak value. Since the shape of the frequency power spectrum during the tsunami event is almost similar to that in the normal state in the neighborhood of ω0, Q can be estimated from sea level datasets in the normal state. Although the amplitude and phase of the impulse response need to be adjusted using the first crest or trough of the observed leading wave, this approach proves to work well in examining the transient responses of Miyako Bay and Kushimoto Bay on the Japanese Pacific coast to incident tsunamis.

Development of Industrial Complex in the Japanese Pacific Coast: Imports of Fossil Fuels and Minerals, Pollution Control, and Nature Conservation, 1930-1973

Development of Industrial Complex in the Japanese Pacific Coast: Imports of Fossil Fuels and Minerals, Pollution Control, and Nature Conservation, 1930-1973

Diversity and distribution of adeonid bryozoans (Cheilostomata: Adeonidae) in Japanese waters

Adeonid bryozoans construct antler-like erect colonies and are common in bryozoan assemblages along the Japanese Pacific coast. The taxonomy of Japanese adeonid species, however, has not been studied since their original descriptions more than 100 years ago. In the present study, adeonid specimens from historical collections and material recently collected along the Japanese coast are examined. Eight adeonid species in two genera were detected, of which Adeonella jahanai sp. nov., Adeonellopsis parvirostrum sp. nov., and Adeonellopsis toyoshioae sp. nov. are described as new species based on the branch width, size and morphology of frontal or suboral avicularia, shape and size of areolar pores, and size of the spiramen. Adeonellopsis arculifera (Canu & Bassler, 1929) is a new record for Japan. Lectotypes for Adeonellopsis japonica (Ortmann, 1890) and Adeonella sparassis (Ortmann, 1890) were selected among Ortmann’s syntypes. Most species of Adeonellopsis around Japan have a southern distribution from Sagami Bay to Okinawa, while A. japonica shows a more northern distribution from Kouchi to Otsuchi. In contrast, Adeonellopsis arculifera was collected only from southwestern Japan. A key to Japanese adeonid species is provided.

Geographic structure evidenced in the toxic dinoflagellate Alexandrium pacificum Litaker (A. catenella – group IV (Whedon & Kofoid) Balech) along Japanese and Chinese coastal waters

The intra-specific diversity and genetic structure within the Alexandrium pacificum Litaker (A. catenella – Group IV) populations along the Temperate Asian coasts, were studied among individuals isolated from Japan to China. The UPGMA dendrogram and FCA revealed the existence of 3 clusters. Assignment analysis suggested the occurrence of gene flows between the Japanese Pacific coast (cluster-1) and the Chinese Zhejiang coast (cluster-2). Human transportations are suspected to explain the lack of genetic difference between several pairs of distant Japanese samples, hardly explained by a natural dispersal mechanism. The genetic isolation of the population established in the Sea of Japan (cluster-3) suggested the existence of a strong ecological and geographical barrier. Along the Pacific coasts, the South–North current allows limited exchanges between Chinese and Japanese populations. The relationships between Temperate Asian and Mediterranean individuals suggested different scenario of large-scale dispersal mechanisms.

A new species of the genus Arhynchite (Annelida, Echiura) from sandy flats of Japan, previously referred to as Thalassema owstoni Ikeda, 1904

A new echiuran, Arhynchite hayaoi sp. n., is described from newly collected specimens from sandy flats of the Seto Inland Sea, Japan, together with many museum specimens, including those once identified as Thalassema owstoni Ikeda, 1904 or Arhynchite arhynchite (Ikeda, 1924). The new species is clearly distinguishable from its congeners by the smooth margin of gonostomal lips and lack of rectal caecum. Brief references are also made to the morphological distinction between the new species and Thalassema owstoni, originally described from the deep bottom on the Japanese Pacific coast.

Tsunami sinusitis

On Friday March 11, 2011, an earthquake and giant tsunami struck the Japanese Pacific coast, killing more than 10 000 people. 1 National Police Agency of JapanDamage Situation and Police Countermeasures associated with 2011 Tohoku district—off the Pacific Ocean Earthquake. http://www.npa.go.jp/archive/keibi/biki/higaijokyo_e.pdf Google Scholar A 31-year-old woman was brought to our hospital a week after the disaster for the treatment of trauma. She had inhaled seawater and nearly drowned. On arrival, she had severe pneumonia and multiple injuries, including a laceration to the top of her foot and a fracture of the thoracic spine. CT of the head showed fluid and opaque material in the maxillary and sphenoid sinuses (figure A, left). Despite treatment with intravenous tazobactam/piperacillin and gentamicin and the subsequent improvement of her pneumonia, she had a persistent fever and her C-reactive protein (CRP) concentration was high at 100 mg/L within 1 week. She underwent irrigation of maxillary sinuses bilaterally under local anaesthesia, during which green-coloured purulent material and sand were washed out (figure B, left). Because of her poor general condition, only the maxillary sinuses could be irrigated. The next day, her temperature decreased; CRP concentration initially fell to 51 mg/L, and then to 7 mg/L 2 weeks later. Culture of the contents of the sinuses showed Pseudomonas aeruginosa, Proteus vulgaris, and Escherichia coli. Given the improvement in her inflammatory indices, we decided to watch her condition carefully without further sinus irrigation.

2）原発事故が地域にもたらしたもの〜福島の大震災の特異性〜

After the catastrophic 2011 Tohoku earthquake and tsunami which struck cities and towns on the Japanese Pacific coast, Fukushima has been the focus of special and serious disaster relief procedures modification regarding nuclear power plant accidents. To date, the Japanese government has repeatedly issued evacuation orders to more than 100,000 residents. Huge numbers of refugees are still uncertain if they can return home and re-cultivate their farm land. Ambiguous public announcements concerning the radiation risks seem to have aggravated feelings of insecurity, fear and the desire to escape, both at home and abroad. This disaster has seriously undermined trust internationally and locally in Fukushima. Harmful rumors added further difficulties. In response to this disaster, local government, medical institutions, care facilities, police, emergency services and the self-defense forces continue to put their utmost effort into reconstruction. This seismic disaster has reminded us that supplies of water, electricity, gas, gasoline and telephone/communication facilities are essential prerequisites for reconstruction and daily life. Disaster and radiation medical association teams actively participated in the rescue efforts, and a number of organized medical teams cared for about 15,000 refugees in 100 shelters. We also visited home-bound patients, who were unable to evacuate from the 20-30 km inner evacuation area. In this relief role, we need to consider the following; (1) professionals, both healthcare and nuclear engineers, must always be prepared for unexpected circumstances, (2) the daily organic cooperation of individuals and units is closely linked to readiness against sudden risks, and (3) appropriate accountability is essential to assuage the fears of residents and refugees. A sincere learning process may benefit those innocent refugees who may be forced to abandon their homes permanently.

Genetic structure in species with shallow evolutionary lineages: a case study of the rare flatfish Verasper variegatus

We examined the genetic population divergence of the spotted halibut Verasper variegatus. A previous report suggested two conservation units for this species along the Japanese Pacific coast. Extending the coverage of the genomes (29 microsatellites and three mitochondrial DNA segments) revealed hitherto-undetected genetic population boundaries. We screened population samples from the major habitats along the Japanese coast and the Yellow Sea coast (East Asian Continent). Significant genetic differentiation was found in every comparison between the habitats. In most cases, the nuclear and mitochondrial population divergences were incongruent, most likely caused by differences between the two genomes in the effects of genetic drift after recent population isolation and bottleneck events. We discuss the ecological and evolutionary mechanisms of the genetic structure as well as the units of conservation. The present study illustrates the merits of wider coverage of genomes in genetic population analysis especially for species with a shallow population history.

A short history of tsunami research and countermeasures in Japan

The tsunami science and engineering began in Japan, the country the most frequently hit by local and distant tsunamis. The gate to the tsunami science was opened in 1896 by a giant local tsunami of the highest run-up height of 38 m that claimed 22,000 lives. The crucial key was a tide record to conclude that this tsunami was generated by a “tsunami earthquake”. In 1933, the same area was hit again by another giant tsunami. A total system of tsunami disaster mitigation including 10 “hard” and “soft” countermeasures was proposed. Relocation of dwelling houses to high ground was the major countermeasures. The tsunami forecasting began in 1941. In 1960, the Chilean Tsunami damaged the whole Japanese Pacific coast. The height of this tsunami was 5–6 m at most. The countermeasures were the construction of structures including the tsunami breakwater which was the first one in the world. Since the late 1970s, tsunami numerical simulation was developed in Japan and refined to become the UNESCO standard scheme that was transformed to 22 different countries. In 1983, photos and videos of a tsunami in the Japan Sea revealed many faces of tsunami such as soliton fission and edge bores. The 1993 tsunami devastated a town protected by seawalls 4.5 m high. This experience introduced again the idea of comprehensive countermeasures, consisted of defense structure, tsunami-resistant town development and evacuation based on warning.

Distribution and bathymetric zonation of deep-sea brittle stars (Echinodermata: Ophiuroidea) off the Japanese Pacific coast

The distribution and bathymetric zonation of deep-sea ophiuroids off the Japanese Pacific coast were analysed. Samples were collected using beam trawls between depths of 60 and 6382 m. In 154 samples, 139 ophiuroid species were found. Data were clustered based on Morisita–Horn similarity index and a dendrogram was constructed. The Japanese Pacific coast can be divided in two major zones. One in the northern part off the Japanese Pacific coast, and another in the region off the central Japanese Pacific coast. In the northern region, five bathymetrical zones were detected at depths of 130–250, 300–500, 500–650, 1100–1500, and 2000–3000 m. In the central region, eight bathymetrical zones were detected at 100–140, 150–250, 200–300, 220–300, 300–400, 400–500, 800–1000, and 1000–1500 m depth. Representative species for each bathymetrical zone are reported.

Implication of onshore-offshore shifts of the Kuroshio axis for plankton biomass in the shirasu fishing grounds off the Japanese Pacific coast

Implication of onshore-offshore shifts of the Kuroshio axis for plankton biomass in the shirasu fishing grounds off the Japanese Pacific coast

239+240Pu and 137Cs concentrations in fish, cephalopods, crustaceans, shellfish, and algae collected around the Japanese coast in the early 1990s

Marine organisms, i.e. fish, cephalopods, crustaceans, shellfish, and algae, were collected in the early 1990s along the Sea of Japan coast and the Japanese Pacific coast and analyzed for their 239+240Pu and 137Cs concentrations. The 239+240Pu concentrations in muscle of fish were below 0.4 mBq/kg wet wt. and the lowest among the analyzed marine organisms. Most 137Cs concentrations in muscle of fish ranged from 100 to 300 mBq/kg wet wt. Higher concentrations of 239+240Pu, ranging from 1.6 to 5.7 mBq/kg wet wt., were observed in viscera of cephalopods than in their muscle. The 239+240Pu concentrations in whole soft tissues of bivalves varied approximately one order of magnitude from 0.8 to 6.1 mBq/kg wet wt., while 137Cs concentrations had little variation, being approximately 60 mBq/kg wet wt. The 239+240Pu concentrations in algae had a wide variation, ranging from 1.7 to 42.3 mBq/kg wet wt., and were higher than those of the other marine organisms. No statistically significant difference in mean concentrations of 239+240Pu was detected among the whole soft tissues of bivalves, viscera of cephalopods and crustaceans, and whole bodies of cephalopods and crustaceans within the 95% confidence limit. The mean concentrations of 137Cs became higher in the order, cephalopods and crustaceans and bivalves, algae, viscera of fish, muscles of fish. The mean concentrations of 239+240Pu were comparable for algae collected along the Japan Sea coast and the Pacific coast. Furthermore, the difference in mean concentrations of 137Cs in algae between the Japan Sea coast and the Pacific coast was not statistically significant within the 95% confidence limit. These results can be considered to indicate no definite influence from radioactive dumping into the Japan Sea by the former USSR and Russia with respect to radioactive pollution of marine organisms collected along the Japanese coast.

東京湾船橋地先におけるアサリの生殖周期

Seasonal gonadal changes were investigated by observation of oocyte diameter and histological examination in samples of Manila clam Ruditapes philippinarum collected from Funabashi waters in Tokyo Bay from May 1988 to September 1991. Gametogenesis was observed from January to November and gonadal maturation was bimodal, similar to southern areas of the Japanese Pacific coast, with peak periods occurring from April to June and from August to October. Gametogenesis in summer was less synchronous between individuals than in winter-spring and was characterized by the prolonged holding of a large number of matured gametes together with partial resorption and new growth of young gametes. Two annual peak periods in the condition factor, which conincided with gonadal maturation, were evident from April to May and August to September. The major spawning period of Manila clam in Funabashi waters was supposed to occur in spring, since gonadal maturation was highly synchronized and the condition factor reached its annual maximal value in this season.

Calcareous Nannoplankton Fossils and their Stratigraphic Meaning

Modern calcareous nannoplanktons have an important role in marine food chain as a primary producelr. Fossils nannoplankton played an important part of the Mesozoic and Cenozoic biological world, and are now accepted as a very useful and accurate index fossil from the Jurassic to Recent Period.In this article recent advance of nannoplankton micropaleontology and biostratigraphy were briefly reviewed. And a calcareous nannoplankton biostratigraphy of the Upper Cenozoic sections in Japanese Pacific coast was presented.In the sections drastic changes of some calcareous nannoplankton species are recognized clearly ; that is, the first appearances of Reticulofenestra japonica, Gephyrocapsa caribbeanica, Gephyrocapsa oceanica, Gephyrocapsa protohuxleyi and Emiliania huxleyi in ascending order, and the disappearances of Sphenolithus abies, Reticulofenestra pseudoumbilica, Discoaster surculus, Discoaster pentaradiatus, Discoaster brouweri, Cyclococcolithus macintyrei. Cyclolithella annula, Reticulofenestra japonica, Reticulofenestra pacifica and Pseudoemiliania lacunosa in ascending order.Based on the first appearances of these species, we can distinguish five calcareous nannoplankton zones in Japan ; that is, Reticulofenestra pseudoumbilica Zone, Reticulofenestra japonica Zone, Reticulofenestra pacifica Zone, Gephyrocapsa oceanica Zone and Emiliania huxleyi Zone in ascending order.Range chart of some important species and calcareous nannoplankton zonation are presented in figure 3, and a stratigraphic correlation is also shown in figure 4.

Lower Pleistocene Invasion and Pleistocene Terraces on the Japanese Pacific Coast

In this paper the Pleistocene terraces and the Lower Pleistocene marine invasion of the Japanese Pacific coast are considered, The writer has divided the Japanese Quaternary deposits into the. following subdivisions: _??_ Of these subdivisions, “dl II” contains Elephas namadieus naumanni MAKIYAMA andd many fossil, marine, shells on the Pacific coast., Between “dl”. beds or below the “Elephas namadicus naumanni M AKIYAMA” horizone, an extensive unconformity has been observed by Japanese writers. The distribution of marine “dl II” beds on the Pacific coast is shown in Fig. a. The “du” beds above “dl II” generally consist of gravel and coarse sand beds. The writer, therefore, concludes that in the early Pleistocene, the Pacific Ocean. invaded. these parts of the Japanese coast. The regions that were covered by the inva _??_ion have been preserved as very smooth flat surfaces, forming coastal terraces I and other flat topographies..Prev ously, the writer divided the Japanese topographic plain into the followir.g subdivisions: A, Du, Dl, Pd Plain. The writer's “Du”, plain agrees with these coastal. terraces and other flat topographies just mentioned. The “Du” plain may therefore be the depositional plain of “dl II, ” which underwent some modifications during the “du” stage. But since no “dl II” are developed on the “Dl” plain, the “Dl” plain may antedate the “dl II” invasion.