Northeastern Coast Of Japan Research Articles

The local phytoplankton community in Shizugawa Bay, Japan, from 2021 to 2022: analysis by DNA metabarcoding

ABSTRACT This study was conducted in Shizugawa Bay, located on the north-eastern coast of Japan, to determine phytoplankton assemblages. Metabarcoding with the PsbA gene and environmental surveys were conducted from May 2021 to January 2022. PCA results showed that phytoplankton assemblages changed with the environmental parameters, such as water temperature and salinity, indicating a clear seasonal pattern. The relative abundance was dominated by Chlorophyta (annual mean 34.9%) > Bacillariophyta (29.1%) > Haptophyta (17.8%) > Dinophyceae (11.7%). It is suggested that many species of Chlorophyta remain without being filtered by shellfish because the dominant representatives were pico-prasinophytes, which are of small size and are difficult for shellfish to capture. Bacillariophytes are thought to have been consumed preferentially since they are known to be a good food source for adult shellfish. Among Dinophyceae, Dinophysis spp. (causing diarrheal poisoning) were dominant throughout the period, while Alexandrium spp. (causing paralytic poisoning) showed relatively low abundance. Phaeocystis spp. (including some toxic species) were the dominant haptophytes. Cyanobacteria tended to appear particularly in summer although their mean relative abundance was less than 3%. Although the data are limited, they provide a useful snapshot of phytoplankton assemblages in Shizugawa Bay and the environmental factors that affect them.

Description of two species of the genus Astrodia Verrill, 1899 (Ophiuroidea, Euryalida, Asteronychidae), including a new species from seamounts in the West Pacific.

Five specimens of Ophiuroidea from deep-sea seamounts in the West Pacific were collected and identified as two species, Astrodiaduospina sp. nov. and Astrodiaabyssicola. The new species, Astrodiaduospina sp. nov., can be distinguished from its congeners by having indistinct or underdeveloped oral papillae, relatively short genital slits, crescent-shaped lateral arm plates, and plate-shaped external ossicles on the aboral surface of the disc. One specimen was identified as Astrodiaabyssicola, which has been reported in the north-western Pacific and the north-eastern coast of Japan. The most recent tabular key of Astrodia was revised with two more key characteristics added, the shape and presence of oral papillae and the number of arm spines. The phylogenetic relationship of Astrodia and Asteronyx was analyzed based on 16S and COI sequences. The discovery of the two species further expanded the geographical distribution of the genus Astrodia.

Influence of normal tide and the Great Tsunami as recorded through hourly-resolution micro-analysis of a mussel shell

We report here hourly variations of Mg/Ca, Sr/Ca, and Ba/Ca ratios in a Mediterranean mussel shell (Mytilus galloprovincialis) collected at the Otsuchi bay, on the Pacific coast of northeastern Japan. This bivalve was living in the intertidal zone, where such organisms are known to form a daily or bidaily growth line comprised of abundant organic matter. Mg/Ca ratios of the inner surface of the outer shell layer, corresponding to the most recent date, show cyclic changes at 25–90 μm intervals, while no interpretable variations are observed in Sr/Ca and Ba/Ca ratios. High Mg/Ca ratios were probably established by (1) cessation of the external supply of Ca and organic layer forming when the shell is closed at low tide, and (2) the strong binding of Mg to the organic layer, but not of Sr and Ba. Immediately following the great tsunami induced by the 2011 Tohoku earthquake, Mg/Ca enrichment occurred, up to 10 times that of normal low tide, while apparent Ba/Ca enrichment was observed for only a few days following the event, therefore serving a proxy of the past tsunami. Following the tsunami, periodic peaks and troughs in Mg/Ca continued, perhaps due to a biological memory effect as an endogenous clock.

Migration patterns and changes in hatching date of neon flying squid Ommastrephes bartramii distributed in the northwestern Pacific Ocean in early summer and caught in fishing grounds off the coast of northeastern Japan in winter

Migration patterns and changes in hatching date of neon flying squid Ommastrephes bartramii distributed in the northwestern Pacific Ocean in early summer and caught in fishing grounds off the coast of northeastern Japan in winter

Lateral variations of 134Cs and 228Ra concentrations in surface waters in the western North Pacific and its marginal sea (2018–2019): Implications for basin-scale and local current circulations

Lateral variations in 134Cs, 137Cs, and 228Ra concentrations (activities) in surface waters off the northeastern coast of Japan, including the subarctic Oyashio Current, subtropical Kuroshio Current, East Sakhalin Current (ESC), and Soya Warm Current (SWC), were examined from July to October in 2018 and 2019. The 134Cs concentrations in the surface seawater samples, decay-corrected to the date of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, were in the range of 0.2–0.9 mBq/L, whereas those transported to the study area with basin-scale currents varied between 0.2 and 1.3 mBq/L; this included the East Kamchatka Current (EKC) for 8 years following the FDNPP accident. Combined with the 228Ra (0.1–1.4 mBq/L) and 137Cs (1.0–1.7 mBq/L) concentrations and the salinity (32.4–34.6), the distribution of 134Cs concentrations indicated that FDNPP-derived radiocesium in this study area was partially transported with the EKC from the northeastern North Pacific. Based on a simple three-component (SWC, ESC, and EKC) mixing model that uses the salinity and 134Cs concentration, the fractions of the EKC showed a maximum value of ~ 0.4 off the southeastern Hokkaido, Japan.

Incorporation of citizens' opinions into the process of earthquake ruins maintenance: A case study of the Great East Japan earthquake ruins in Miyagi Prefecture

AbstractThe Great East Japan Earthquake struck in March 2011, causing a huge tsunami on the northeastern coast of Japan. In the disaster area, there has been a movement to preserve the damaged structures as earthquake ruins. In this study, the characteristics of establishing consensus were investigated by clarifying how the earthquake ruins have been preserved and removed, and how the opinions of citizens were accounted for in the process of maintaining these sites. The study focused on 21 earthquake ruins in Miyagi Prefecture, which were the closest to the epicenter. We extracted 30 elements from the earthquake ruins maintenance process and created labels for them. From these, we prepared time‐series charts and flowcharts and discussed the relation between entities and citizens' opinions regarding the maintenance process. We clarified four stages pertaining to the preserved ruins and found four types of relationships between the major opinions and treatment decisions. Furthermore, the periods following the earthquake were divided into three phases: pioneering, deliberation, and implementation. Consequently, we suggested that citizens' opinions, coupled with expert advice, could be used to help establish consensus in an incremental manner when making administrative decisions.

The Summer/Fall Variability of the Southern East/Japan Sea in the ENSO Period

The summer/fall variability of the upper ocean circulations and properties of the East/Japan Sea occurring during the El Nino-Southern Oscillation (ENSO) period is investigated by use of the high-resolution HYCOM reanalysis data. From August to November of the La Nina period, the inflow through the Korea/Tsushima Strait is intensified, and so are the East Korean Warm Current (EKWC) and the Nearshore Branch of the Tsushima Warm Current (NBTWC) in the southern East/Japan Sea. The intensified EKWC induces an offshore current anomaly near 36°N, weakening the anticyclonic gyre circulation in Ulleung basin, and the intensified NBTWC leads to weakening of the Offshore Branch of the Tsushima Warm Current (OBTWC). The sea surface temperature begins to increase from the northeastern coast of Japan in August, and its positive anomalies expand to the largest area of southern East/Japan Sea in October and last until November. The positive anomalies of sea surface salinity are mainly observed along the south and east coast of Korea. The cyclonic gyre circulation anomaly in Ulleung Basin is accompanied by the negative SSH anomaly and shallowing of the upper ocean isopycnal lines, which leads to substantial cooling of the subsurface water. The reverse is true in the El Nino period.

Lacydoniidae (Annelida) Off the Coast of North-eastern Japan: A Description of Lacydonia japonica sp. nov.

Lacydonia japonica sp. nov. (Annelida, Lacydoniidae) is described based on material found in sediments collected off the Pacific coast of northern Honshu, Japan, at depths of 262 m and 407 m. The sediments were obtained by a remotely operated vehicle equipped with a suction sampler during a Tohoku Ecosystem-Associated Marine Sciences (TEAMS) project in 2019. Lacydonia japonica sp. nov. belongs to the eyeless group of lacydoniids and is discriminated from the morphologically most similar congener, Lacydonia papillata Uschakov, 1958 by its reddish pigments on both the dorsal and ventral parapodial cirri and four pigment spots on the pygidium. To assess the phylogenetic position of the new species among other lacydoniids for which sequence data are available in public databases, analyses were performed using the mitochondrial cytochrome c oxidase subunit I (COI) and 16S rRNA, as well as the nuclear 18S rRNA and 28S rRNA genes. We additionally obtained some lacydoniids by sledging off western Japan, but these were severely fragmented and broken during collection. Using the paucity of morphological data, they were left unidentified as Lacydonia sp. but included in the molecular analyses. Genetic distances between Lacydonia eliasoni Hartmann-Schröder, 1996, Lacydonia japonica, and Lacydonia sp. off western Japan were 10.4-17.1% uncorrected p-distance (11.3-18.6% K2P) in terms of 658-bp COI sequences.

Field surveys and numerical modeling of the August 2016 Typhoon Lionrock along the northeastern coast of Japan: the first typhoon making landfall in Tohoku region

Typhoon Lionrock, also known as the national number 1610 in Japan, caused severe flooding in east Japan in August 28–31, 2016, leaving a death toll of 22. With a maximum sustained wind speed of ~ 220 km/h from the Joint Typhoon Warning Center’s best track, Lionrock was classified as a category 4 hurricane in Saffir–Simpson Hurricane Wind Scale and as a typhoon in Japan Meteorological Agency’s scale. Lionrock was among unique typhoons as it started its landfall from north of Japan. Here, we studied the characteristics of this typhoon through tide gauge data analysis, field surveys and numerical modeling. Tide gauge analysis showed that the surges generated by Lionrock were in the ranges of 15–55 cm with surge duration of 0.8–3.1 days. Our field surveys revealed that the damage to coastal communities/structures was moderate although it caused severe flooding inland. We measured a maximum coastal wave runup of 4.3 m in Iwaisaki. Such a runup was smaller than that generated by other category 4 typhoons hitting Japan in the past. Our numerical model was able to reproduce the storm surge generated by the 2016 Typhoon Lionrock. This validated numerical model can be used in the future for typhoon-hazard studies along the coast of northeastern Japan. Despite relatively small surge/wave runups in coastal areas, Lionrock’s death toll was more than that of some other category 4 typhoons. We attribute this to various primary (e.g., flooding, surges, waves, strong winds) and secondary (e.g., landslides, coastal erosions, debris flows, wind-blown debris) mechanisms and their combinations and interactions that contribute to damage/death during a typhoon event.

What Are the Gender Impacts of the WTO on Local Communities?: South Korea’s Import Restriction on Sea-Squirts from Nuclear Affected Areas in Japan

In 2011, an earthquake triggered a tsunami off the northeastern coast of Japan, damaging the Fukushima Dai-ichi Nuclear Power Plant, which released nuclear material into the Pacific ocean. Soon afterwards, South Korea raised concerns about food safety and imposed a ban on imports of Japanese seafood from the Tohoku region of Honshu. The study reported in this article examined the impact of the South Korean government’s import bans of Japanese seafood on women in that economic sector. The focus of the study was a recent WTO decision to uphold the ban, in spite of the fact that Japan is able to prove the seafood meets safe, approved levels of radiation. The research focussed on the effect of the ban and its continuation on the women involved in the sea-squirts industry in Miyagi prefecture of Tohoku. The article concludes that it is time for the WTO to consider the impact of their decisions on women and take women’s issues into account during their decision making. Women in trade, WTO, food safety, importance of women in trade, Japan, South Korea, Fukushima, seafood

Reduced biomass of the kelp Saccharina japonica cumulatively affects gonad production of sea urchins over ensuing years off northeastern Japan

The annual kelp Saccharina japonica grows along the northeastern coast of Japan, making the coast highly productive for the fishery for herbivores such as sea urchins and abalones. The biomass of the kelp along this coast drastically varies each year due to variable environmental factors, i.e., seawater temperature and nutrient concentrations, during the period of kelp germination. We carried out a field investigation to elucidate how the gonad production fluctuates in an environment where the kelp production varies each year. Seaweed biomass and gonad weight of the sea urchin Mesocentrotus nudus were examined monthly from March 2015 through December 2018. The kelp was abundant and the gonad index (= gonad ∕ body weight × 100) of the sea urchins reached more than 20% in 2015. However, in the following 3 years (2016 to 2018), the kelp was nearly absent from the area and the maximum gonad index was significantly less than that in the kelp-abundant year (2015). During the kelp-scarce 3 years, the gonad index showed a significant decrease from one kelp-scarce year to another, indicating that the effect of a poor algal growth on the gonad production of sea urchins was cumulative over the following years.

NUMERICAL AND HYDRAULIC EXPERIMENTS ON BORE PRESSURE DUE TO TSUNAMI

The 2011 Tohoku earthquake tsunami struck a wide area of the northeastern coast of Japan, and many coastal structures and buildings were damaged by the tsunami. Most of the buildings were damaged by the tsunami wave pressure. After the tsunami, characteristics of tsunami waive pressures have been investigated by many researcher, and are being clarified. As shown in previous studies, there are three regimes charactering the vertical pressure profiles. The first one is the impulsive pressure, which is observed just after the tsunami-bore impacted structures. In this regime, strong hydrodynamic pressures are generated by the fluid-solid impact process. After that, the bore pressure is observed, and both the hydrodynamic and hydrostatic pressures contribute the pressure profile. After that, the flow near the structures reaches a quasi-steady state, and the pressure profile becomes hydrostatic. Most of the evaluation equations of tsunami wave pressure proposed by the previous studies can be used against the impulsive pressures and the pressures in the quasi-steady-state regime. On the other hand, the characteristics and quantitative evaluations of the bore pressure remain immature. In this study, in order to clarify the characteristics of the bore pressure, experiments on the bore pressure are carried out, and furthermore, three-dimensional numerical simulations are also carried out.

Ontogenetic habitat shift of age-0 Japanese flounder Paralichthys olivaceus on the Pacific coast of northeastern Japan: differences in timing of the shift among areas and potential effects on recruitment success

Ontogenetic habitat shift and feeding habits in the shallow (< 15 m) and deep (30–80 m) habitats of age-0 Japanese flounder Paralichthys olivaceus in Sendai Bay, the Pacific coast of northeastern Japan, were examined to understand the mechanisms that potentially enable area-specific high recruitment success. The flounder was able to use the shallow nursery habitat for about 1 year, until the next summer of their settlement (June–August) when they had reached 250 mm total length (TL). In addition, age-0 flounder between 150 and 250 mm TL used both shallow and deep habitats from winter to the next summer of their settlement, where species, size, and availability of potential food and susceptibility to predators are considerably different. These area-specific characteristics in Sendai Bay are clearly different from other areas around Japan that have been described in the literature: shorter residence in the shallow habitat and smaller size at emigration to the deep habitat. The characteristics in Sendai Bay seem to be enabled by prolonged good feeding conditions in the shallow habitat, which result from an abundant food supply and relatively lower temperature that does not exceed the uppermost temperature (25 °C) for maximum growth of the age-0 flounder. We consider that the prolonged better feeding conditions in the shallow habitat in the study area for ca. 1 year after settlement contribute to higher recruitment success.

Biological report of a giant deep-sea squid Onykia robusta collected from the Sanriku Coast, Japan: implications for low genetic diversity

Despite their appeal to both researchers and the general public, the biology of giant deep-sea squids remains enigmatic. The robust clubhook squid Onykia robusta (Verrill, 1876) is one of the largest living deep-sea squids. It is distributed across the northern Pacific Ocean between Japan and California, including the Bering Sea. Although this species has been frequently caught by fishermen, its biology remains largely unknown. In this paper, I report biological data from one specimen, which was collected from the Sanriku Coast of northeastern Japan. The individual was a sexually mature female (total length: 246 cm, mantle length: 125 cm, wet body weight: 26 kg) and with oocytes that may have been large enough to begin yolk accumulation. Low genetic diversity within this species was implied by comparative analysis of the mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) gene (n = 5; additional four sequences sourced from GenBank). The low nucleotide diversity (π = 0.0044) was similar to that of the deep-sea giant squid Architeuthis dux, which is known from mtDNA analysis to lack discernible population structure, showing no genetic differentiation among samples from different regions of the Pacific. Architeuthis dux has been hypothesized to be highly migratory, probably through a pelagic paralarval stage. My data suggest the presence of a common dispersal strategy among the deep-sea giant squids.

Living status, economic hardship and sleep disturbance were associated with subjective shoulder pain in survivors of the Great East Japan Earthquake: A cross sectional study.

The Great East Japan Earthquake and devastating Tsunami hit hard everything on the northeastern coast of Japan. This study aimed to determine socio-psychological factors for "subjective shoulder pain" of the survivors at 2 years evaluated by a self-report questionnaire. Between November 2012 to February 2013, survivors replied to the self-report questionnaire, and 2275 people consented to join this study. Living status was divided into 5 categories (1. same house as before the earthquake (reference group), 2. temporary small house, 3. apartment, 4. house of relatives or acquaintance, 5. new house) and economic hardship was divided into 4 categories (1. normal (reference group), 2. a little bit hard, 3. hard, 4. very hard). Gender, age, body mass index, living areas, smoking and drinking habits, complications of diabetes mellitus and cerebral stroke, working status, and walking time were considered as the confounding factors. Kessler Psychological Distress Scale of ≥10/24 and Athens Insomnia Scale of ≥6/24 points were defined as a presence of psychological distress and sleep disturbance, respectively. We used multiple logistic regression analysis to examine the association of shoulder pain with living environment, economic hardship, psychological distress, and sleep disturbance at 2 years after the earthquake. There were significant differences in the risk of having shoulder pain in those with "apartment" (OR=1.74, 95% CI=1.03-2.96), "house of relatives or acquaintance" (OR=2.98, 95% CI=1.42-6.25), economic hardship of "hard" (OR=1.71, 95% CI=1.08-2.7) and "very hard" (OR=2.51, 95% CI=1.47-4.29), and sleep disturbance (OR=2.96, 95% CI=2.05-4.27). Living status of "apartment" and "house of relatives or acquaintance", economic hardship of "hard" and "very hard", and "sleep disturbance" were significantly associated with shoulder pain.

A Note about the Great East Japan Earthquake and Tsunami in 2011 from a Fisheries Perspective Five Years Later

The 9.0 magnitude earthquake that struck off the northeastern coast of Japan in March 2011 (Fujii et al. 2011) caused a massive tsunami that severely damaged the Pacific coast of the Tohoku region....

Psychological trauma after the Great East Japan Earthquake.

The Great East Japan Earthquake (GEJE) struck the northeastern part of Japan on 11 March 2011 and triggered a devastating tsunami, causing widespread destruction along the coast of northeastern Japan. The tsunami also led to an accident at the Fukushima Daiichi nuclear power plant. Incidents occurring in such major disasters are known to lead to psychological trauma. This paper has summarized English-language documentation regarding GEJE-related psychological trauma or post-traumatic stress disorder (PTSD). Research thus far has reported the possibility of higher probable PTSD prevalence among residents of the GEJE areas than in the average Japanese population during normal times. At the very least, many people have experienced trauma symptoms at self-recognition levels 1 year or longer after the disaster. It appears that the percentage of persons with high PTSD risk was higher in regions with radiation-related impacts than in regions where the main damage was caused by the earthquake and tsunami. Results have not been limited to showing relations between severe exposure to a traumatic event and PTSD symptoms but also show that a variety of factors, including social factors, has been shown to interact with PTSD symptoms. The fact that Japanese society as a whole united against the trauma of the GEJE may have worked to minimize the effects of trauma. To grasp a full picture of the effects of psychological trauma due to the GEJE, further surveys and research are necessary. It will be necessary to continue engagements related to these problems and issues into the future.

Psychological Distress and the Risk of Withdrawing From Hypertension Treatment After an Earthquake Disaster.

This study examined the association between psychological distress and the risk of withdrawing from hypertension treatment (HTTx) 1 year after the earthquake disaster in the coastal area affected by the Great East Japan Earthquake (GEJE). Using cross-sectional data from 2012, we studied people over 20 years of age living in Shichigahama Town, Miyagi, on the northeastern coast of Japan, which had been severely inundated by the tsunami that followed the GEJE in 2011. A total of 1014 subjects were categorized as in need of HTTx. Withdrawing from HTTx was assessed by using a self-reported questionnaire. Subjects with a higher degree of psychological distress (Kessler-6 [K6] score ≥ 13) exhibited a significantly higher risk of withdrawing from HTTx, compared with subjects with a lower degree of psychological distress (K6 score ≤ 12; odds ratio=4.0; 95% confidence interval: 1.3-10.6, P<0.01). This study indicated that psychological distress is a risk factor for withdrawing from HTTx in post-disaster settings. Our data suggested that the increased risk of withdrawing from HTTx associated with post-disaster psychological distress may underlie the increased prevalence of vascular diseases after the earthquake disaster in coastal areas affected by the tsunami. (Disaster Med Public Health Preparedness. 2017;11:179-182).

Influence of living environments and working status on low back pain for survivors of the Great East Japan Earthquake.

The Great East Japan Earthquake and devastating Tsunami caused irreparable damage on the northeastern coast of Japan. This study aimed to examine the influencing factors of "Living environment" and "Working status" on low back pain for the survivors of the earthquake evaluated by a self-report questionnaire. Between 2011 and 2013, survivors replied to the self-report questionnaire, and 986 people consented to join this study. The living environment was divided into 3 categories (1. Living in the same house as before the earthquake, 2. Living in a safe shelter or temporary small house, 3. Living in a house of relatives or apartment house) and working status was divided into 5 categories (1. Unemployed before the earthquake, 2. Unemployed after the earthquake, 3. Decrease in income, 4. Different occupation after the earthquake, 5. The same occupation as before the earthquake). Age, gender, living areas, past history of arthritis, arthropathy, osteoporosis, sleep disturbance, psychological distress, and economic status were considered as confounding factors. Generalized estimating regression models with logit link function were used because outcome variables are repeatedly measured and binomial. We evaluated the correlation between the presence/severity of low back pain over time and housing status/working status at 1 year after the earthquake. There were no significant differences between age, gender, living areas, working status, or living environment before or after the earthquake. There was no significant difference in the risk of having low back pain in living environment or gender. There was significant difference in the risk of having low back pain in those with "Decrease in income" (OR=1.93, 95% CI=1.23-3.03) and "The same occupation as before the earthquake" (OR=1.67, 95% CI=1.1-2.52). Though living environment has little effect, "Decrease in income" and "The same occupation as before the earthquake" have strong influences on low back pain.

Multi-Scale Bridge Wash Out Simulation During Tsunami by Using a Particle Method

n 2011, the huge tsunami caused by the great east Japan earthquake devastated many infrastructures in pacific coast of north eastern Japan. Particularly, collapse of bridges caused a traffic disorder and these collapse behaviors led to delay of recovery after the disaster. In this study, the bridge wash away accident is selected as a target issue, and it is represented by a numerical simulation. For this purpose, Smoothed Particle Hydrodynamics (SPH) Method, which is one of the pure mesh free methods, is utilized for the rigid body motion simulation. In this study, rigid body motion is introduced for the fluid-rigid interaction behavior during bridge wash away simulation. In the numerical analysis, the upper bridge structure is washed away by receiving an impact fluid force. The wash away simulation of two types of the bridge girder showed good agreement with the real accident on the great east Japan earthquake tsunami. © Owned by the authors, published by EDP Sciences, 2016 Language: en