Southwest Of Japan Research Articles

Climate change impacts on migration of Pinus koraiensis during the Quaternary using species distribution models

Clarifying the influences of paleoclimate changes on the disjunct distribution formation of plants allows a historical and mechanical understanding of current vegetation and biodiversity. This study investigated the influences of paleoclimate changes on the present disjunct distribution formation of Pinus koraiensis (Korean pine) using species distribution modeling. A species distribution model (SDM) was built using maximum entropy principle algorithms (MaxEnt), data from 152 occurrences of the species, and four bioclimatic variables at 2.5 arcminute (approximately 5 km) spatial resolution. The simulation revealed the excellent fit of the MaxEnt model performance, with an area under the curve (AUC) value of 0.922 and continuous Boyce index (BCI) value of 0.925 with fivefold cross-validation. The most important climatic factor was the minimum temperature of the coldest month. Suitable habitats for the species ranged between − 30.1 and − 4.1 °C. Projected suitable habitats under the Last Glacial Maximum (approximately 22,000 years ago [ka BP]: LGM) period showed wide distributions in eastern China, the southern part of the Korean Peninsula, and the Japanese Archipelago. After the mid-Holocene (approximately 6 ka BP), the suitable habitats expanded northwards in continental regions and retreated from both north and southwest of Japan. This eventually formed disjunct suitable habitats in central Japan. An increase in temperature after the LGM period caused the migration of P. koraiensis toward new, suitable habitats in continental Northeast Asia, while species in the Japanese Archipelago retreated, forming the present disjunct distributions.

Is rice cultivation sink or source of nitrogen for a Japanese river?

The balance of nitrate nitrogen (NO3–N) in the Ohno River basin on Kyushu, southwest of Japan was investigated based on observed flow discharges and NO3–N concentrations in river water over the period from 1969 to 2018 (half a century). The dependence of NO3–N load on flow discharge at Shirataki in the river was quantified for the cultivation season (May–September) and the fallow period (October–April) in order to evaluate the impact of rice cultivation on the water quality in the river. Measured results in the 50 year period show that NO3–N loads for the cultivation season were smaller than those for the fallow period for a given flow discharge which was less than 100 m3/s. This indicates that the rice cultivation contributes to the decrease in the NO3–N load in the effluent water discharged from paddies which is 18% of the whole basin to the river. Rice cultivations in a watershed can be a source of nutrients induced by excess fertilizer application or a sink because nutrients in inundating water can be assimilated by rice plants to aid their growth. A model presented in this study incorporates the management of water and fertilizer in the paddies, and describes the balance of NO3–N in the basin. The model assumes that rice plants assimilate nitrogen in the soil resulting from fertilization. This occurs preferentially when it is sufficient and, when the rice plants themselves utilize nitrogen in the inundated water after the nitrogen in the soil is depleted. The model was found to substantially reproduce measured NO3–N loads in the Ohno River for the cultivation season in the period (1969–2018). This suggests that the difference in the NO3–N loads for a given flow discharge between the cultivation season and the fallow period at Shirataki in the river was induced through the uptake of nitrogen by rice plants.

Geological characteristics of the Nankai Trough subduction zone and their tectonic significances

The Nankai Trough subduction zone is a typical subduction system characterized by subduction of multiple geological units of the Philippine Sea Plate (the Kyushu-Palau Ridge, the Shikoku Basin, the Kinan Seamount Chain, and the Izu-Bonin Arc) beneath the Eurasian Plate in the southwest of Japan. This study presents a geophysical and geochemical analysis of the Nankai Trough subduction zone in order to determine the features and subduction effects of each geological unit. The results show that the Nankai Trough is characterized by low-gravity anomalies (−20 mGal to −40 mGal) and high heat flow (60–200 mW/m2) in the middle part and low heat flow (20–80 mW/m2) in the western and eastern parts. The crust of the subducting plate is 5–20 km thick. The mantle composition of the subducting plate is progressively depleted from west to east. Subduction of aseismic ridges (e.g., the Kyushu-Palau Ridge, the Kinan Seamount Chain, and the Zenisu Ridge) is a common process that leads to a series of subduction effects at the Nankai Trough. Firstly, aseismic ridge or seamount chain subduction may deform the overriding plate, resulting in irregular concave topography along the front edge of the accretionary wedge. Secondly, it may have served as a seismic barrier inhibiting rupture propagation in the 1944 Mw 8.1 and 1946 Mw 8.3 earthquakes. In addition, subduction of the Kyushu-Palau Ridge and hot and young Shikoku Basin lithosphere may induce slab melting, resulting in adakitic magmatism and the provision of ore-forming metals for the formation of porphyry copper and gold deposits in the overriding Japan Arc. Based on comparisons of their geophysical and geochemical characteristics, we suggest that, although the Izu-Bonin Arc has already collided with the Japan Arc, the Kyushu-Palau Ridge, which represents a remnant arc of the Izu-Bonin Arc, is still at the subduction stage characterized by a single-vergence system and a topographic boundary with the Japan Arc.

Variability and change of precipitation and flood discharge in a Japanese river basin

Study regionThe Banjo River basin on Kyushu Island in the southwest of Japan. Study focusThis study focuses on the impact of local and/or large scale climate change on the river flow in the small and steep river basin. The variability, trend, correlation and change of extreme and mean precipitation and river (flood) runoff are investigated. New hydrological insightsIn the small and steep river basins of Japan, the maximum annual flood runoff which occurs in the wet season, is well correlated with maximum precipitation on a daily time scale. Daily flow and precipitation data recorded in the basin from 1960 to 2015, have a correlation coefficient R2 = 0.72. A high variability of the maximum and mean annual flows, and significant rising trends in daily extreme precipitation and river (flood) flows were also found in the data analysis. The maximum annual flood has increased on average by 5.98 m3/s per year from 330 m3/s in 1960; this increase is fully accounted for by the trend in observed maximum annual precipitation which is 1.1 mm/day per year. On an annual timescale maximum precipitation and maximum flood discharges have become substantially higher in phase with the ENSO (El Nino-Southern Oscillation) in the Pacific Ocean. Time frequency analyses revealed that a periodic component of the annual maximum flood flow in the Banjo River basin with a period of about 6 to 8 years has become significant since the beginning of the 21 st century. The number of days with more than 100, 200, 300, 400 and 500 m3/s flows has increased, which is important for flood control planning.

The 2016 Mw 5.9 earthquake off the southeastern coast of Mie Prefecture as an indicator of preparatory processes of the next Nankai Trough megathrust earthquake

Megathrust earthquakes have occurred repeatedly at intervals of 100 to 150 years along the Nankai Trough, situated in the southwest of Japan. Given that it has been 70 years since the last event, the occurrence of the next devastating earthquake is anticipated in the near future. On April 1, 2016, a moderate earthquake (Mw 5.9, MJMA 6.5) occurred off the southeastern coast of Mie Prefecture in the source region of the 1944 Tonankai earthquake (Mw 8.2). In this study, we investigated the influence of the 2016 earthquake on future megathrust earthquakes. We first determined the hypocenter distributions using a precise velocity structure obtained from seismic surveys in the source region. Using data obtained from the DONET ocean-bottom observation network, we found that this earthquake occurred along the plate boundary fault, which is also believed to have slipped during past megathrust earthquakes. We then performed a preliminary numerical simulation to reproduce the occurrence of a moderate earthquake in the middle of a megathrust earthquake cycle. We used a hierarchical asperity model, in which smaller asperities causing moderate earthquakes are embedded in a hyper-asperity that serves as the source region of megathrust earthquakes. The simulation shows that moderate earthquakes, caused by ruptures of a smaller asperity, occur as a result of shrinkage of strongly coupled areas in the hyper-asperity. This result is consistent with the observation that the hypocenter of the 2016 earthquake was located at the edge of a strongly coupled region along the plate boundary. The simulation also reproduced postseismic slip (afterslip/slow slip) along the plate boundary updip of the hyper-asperity, which is consistent with the observations of slow slip events and very-low-frequency earthquakes after the 2016 earthquake. Thus, the occurrence of the moderate earthquake offshore southeastern Mie Prefecture in the middle of the megathrust earthquake cycle implies that the shrinkage of the strongly coupled area along the plate boundary is occurring as a preparatory process for the next megathrust earthquake in the region.

Shallow very-low-frequency earthquakes accompany slow slip events in the Nankai subduction zone

Recent studies of slow earthquakes along plate boundaries have shown that tectonic tremor, low-frequency earthquakes, very-low-frequency events (VLFEs), and slow-slip events (SSEs) often accompany each other and appear to share common source faults. However, the source processes of slow events occurring in the shallow part of plate boundaries are not well known because seismic observations have been limited to land-based stations, which offer poor resolution beneath offshore plate boundaries. Here we use data obtained from seafloor observation networks in the Nankai trough, southwest of Japan, to investigate shallow VLFEs in detail. Coincident with the VLFE activity, signals indicative of shallow SSEs were detected by geodetic observations at seafloor borehole observatories in the same region. We find that the shallow VLFEs and SSEs share common source regions and almost identical time histories of moment release. We conclude that these slow events arise from the same fault slip and that VLFEs represent relatively high-frequency fluctuations of slip during SSEs.

Recombinant type Human mastadenovirus D85 associated with epidemic keratoconjunctivitis since 2015 in Japan.

The aim of this study was to report the emergence of a recombinant human mastadenovirus (HAdV) type 85 (HAdV-85) and to describe its genomic and clinical characteristics. The strains were detected and identified in Japan in cases of adenoviral conjunctivitis including epidemic keratoconjunctivitis (EKC). The type was designated as HAdV-85 based on the novel combination of penton base (P = HAdV-37), hexon (H = HAdV-19), and fiber (F = HAdV-8). The whole genome sequence determined for HAdV-85 was compared against sequences of other types in the same species. The results of the phylogenetic analysis suggested a recombinant origin between HAdV-53 and HAdV-64, which have been two major causes of adenoviral EKC in Japan over the past decade. During the period between 2008 and 2016 in Kumamoto city, southwest of Japan, 311 cases diagnosed with conjunctivitis were diagnosed as being the consequence of adenoviral infections. Among them, 11 cases were determined to have been caused by HAdV-85 since 2015. Thus, HAdV-85 could be an emerging causative agent of adenoviral conjunctivitis.

Stochastic Extended Simulation (EXSIM) of M<sub>w</sub> 7.0 Kumamoto-Shi earthquake on 15 April 2016 in the Southwest of Japan using the SCEC Broadband Platform (BBP)

Ground motions for Mw 7.0, 15 April 2016, Kumamoto-Shi earthquake of Japan are simulated employing Stochastic Extended Simulation (EXSIM) methodology within the Southern California Earthquake Centre (SCEC) Broadband Platform (BBP) version 15.3.0, utilizing the strong ground motion data from K-NET and KiK-net. Residuals [(ln(data/model)] are plotted as a function of hypocentral distance for a subset of eight periods. Trail simulations are run by varying stress drop until a better match of residuals is obtained. Validation exercise is run with a new data set to ascertain the accuracy of simulations. The results exhibit a close match between the recorded and predicted data. Adopting the validated seismological model of this study, ground motions are predicted at three important sites, which are devoid of strong-motion stations. These results can be used as inputs for conducting dynamic, response spectrum analysis of structures, liquefaction potential of soils, stability analysis and landslide runout estimation of slopes.

The Gondou hydrothermal field in the Ryukyu Arc: A huge hydrothermal system on the flank of a caldera volcano

AbstractHigh‐resolution geophysical mapping was conducted from an autonomous underwater vehicle on the flank of Daisan‐Kume Knoll in the Ryukyu Arc, southwest of Japan. 1 m resolution bathymetry identified 264 spires, 173 large mounds and 268 small mounds within a depression that is up to 1600 m wide and up to 60 m deep, at water depths between 1330 and 1470 m. Hydrothermal venting is strongly inferred from the observation of plumes in sidescan sonar imagery and positive temperature anomalies over the spires and mounds. This field, named the Gondou Field, has a giant mound G1 with a diameter of 280 m and a height of 80 m. Mound G1 has distinctive summit ridges composed of multiple spires where acoustic plumes with temperature anomalies up to 1.12°C are observed, indicative of high‐temperature venting. Other than mound G1, a number of active large mounds more than 30 m wide and spires over 10–22 m tall are common and they concentrate in the central and southern areas of the field, suggesting that these areas are the center of present hydrothermal activity. Acoustic plumes imaged by side‐scan sonar at the Gondou Field are different in character from bubble plumes imaged in other hydrothermal fields in the Ryukyu Arc. The plumes are diffused and deflected as they rise through the water column and have a shape consistent with black smokers.

Smoking and secondhand smoke exposure and prevalence of depressive symptoms during pregnancy in Japan: baseline data from the Kyushu Okinawa Maternal and Child Health Study

Epidemiological evidence on the relationship between smoking and secondhand smoke (SHS) exposure and depressive symptoms during pregnancy has been limited. The present cross-sectional study examined this issue in Japan.Between April 2007 and March 2008, 1757 pregnant women who lived in one of seven prefectures on Kyushu Island in southern Japan or in Okinawa Prefecture, an island chain in the southwest of Japan, participated in the Kyushu Okinawa Maternal and Child Health Study, a prebirth cohort study. In the present study, data on 1745 pregnant women were available for analysis. Information on smoking, SHS exposure, depressive symptoms, and potential confounding factors was obtained through a self-administered questionnaire. Depressive symptoms were defined as present when subjects had a Center for Epidemiologic Studies Depression Scale score of 16 or higher. Adjustment was made for age, gestation, region of residence, number of children, family structure, household income, education, job type, history of depression, and family history of depression.The prevalence of depressive symptoms during pregnancy was 19.2%. Compared with having never smoked, both former and current smoking was independently associated with a higher prevalence of depressive symptoms during pregnancy: the adjusted odds ratios (ORs) were 1.39 (95% CI: 1.06–1.83) and 2.49 (95% CI: 1.36–4.45), respectively. Also, 3.0 to 7.9 and 8.0 or more pack-years of smoking were independently positively related to depressive symptoms during pregnancy: the adjusted ORs were 1.55 (95% CI: 1.08–2.22) and 1.97 (95% CI: 1.26–3.03), respectively (P for trend = 0.0005). Among the 1183 subjects who had never smoked, current SHS exposure at home was independently positively associated with depressive symptoms during pregnancy: the adjusted OR was 1.51 (95% CI: 1.003–2.30).Former and current smoking, 3.0 or more pack-years of smoking, and current SHS exposure at home may be positively associated with depressive symptoms during pregnancy.

Variations in seismic velocity distribution along the Ryukyu (Nansei-Shoto) Trench subduction zone at the northwestern end of the Philippine Sea plate

The Ryukyu (Nansei-Shoto) island arc-trench system, southwest of Japan, is formed by the subduction of the Philippine Sea (PHS) plate. Among the subduction zones surrounding the Japan Islands, the Ryukyu arc-trench system is unique in that its backarc basin, the Okinawa Trough, is the area with current extensively active rifting. The length of the trench is around 1400 km, and the geological and geophysical characteristics vary significantly along the trench axis. We conducted multichannel seismic (MCS) reflection and wide-angle seismic surveys to elucidate the along-arc variation in seismic structures from the island arc to the trench regions, shooting seven seismic lines across the arc-trench system and two along-arc lines in the island arc and the forearc areas. The obtained P-wave velocity models of the Ryukyu arc crust were found to be heterogeneous (depending on the seismic lines), but they basically consist of upper, middle, and lower crusts, indicating a typical island arc structure. Beneath the bathymetric depressions cutting the island arc—for example, the Kerama Gap and the Miyako Saddle—the MCS record shows many across-arc normal faults, which indicates the presence of an extensional regime along the island arc. In the areas from the forearc to the trench, the subduction of the characteristic seafloor features on the PHS plate affects seismic structures; the subducted bathymetric high of the Amami Plateau is detected in the northern trench: the Luzon–Okinawa fracture zone beneath the middle and southern trenches. There are low-velocity (<~4.5 km/s) wedges along the forearc areas, except for off Miyako-jima Island. The characteristic high gravity anomaly at the forearc off Miyako-jima Island is caused not by a bathymetric high of a large-scale accretionary wedge but by shallower materials with a high P-wave velocity of ~4.5 km/s.Graphical Position of the seismic survey lines in the Ryukyu arc-trench system (right) and P-wave velocity models for the lines perpendicular to the trench axis (left). The contour interval is 2.5 km/s. The vertical blue line shows the position of the trench axis.

A revision of the distribution of sea kraits (Reptilia, Laticauda) with an updated occurrence dataset for ecological and conservation research.

The genus Laticauda (Reptilia: Elapidae), commonly known as sea kraits, comprises eight species of marine amphibious snakes distributed along the shores of the Western Pacific Ocean and the Eastern Indian Ocean. We review the information available on the geographic range of sea kraits and analyze their distribution patterns. Generally, we found that south and south-west of Japan, Philippines Archipelago, parts of Indonesia, and Vanuatu have the highest diversity of sea krait species. Further, we compiled the information available on sea kraits’ occurrences from a variety of sources, including museum records, field surveys, and the scientific literature. The final database comprises 694 occurrence records, with Laticauda colubrina having the highest number of records and Laticauda schistorhyncha the lowest. The occurrence records were georeferenced and compiled as a database for each sea krait species. This database can be freely used for future studies.

Amami park and island tourism: Sea, land and islandness at a site of simulation

Amami Park is a nature and culture centre located in the Amami islands in the southwest of Japan. Objects are displayed on one site and marketed for tourists, whether on-island, in the Amami islands or more distant. This article discusses Amami Park in terms of the themes of sea, land and islandness, which emerged as topics for discussion during the research process with regard to how Amami Park represents itself, and the cultural meaning of such presentation and its relevance in the tourist industry. Amami Park offers a range of media through which to showcase the history, nature and culture of the Amami islands, and it offers numerous objects, audiovisual displays and other types of media with much description, representation and celebration of local and archipelagic identity. In this island setting, the article discusses the objects and their presentation, focussing on theme park analysis, cultural tourism and self-representation. Drawing on theoretical ideas pertaining to the notion of “simulation”, as applied to the recontextualization of disparate items in one location, the article shows how this particular nature and culture centre can be viewed as a microcosm of broader social and touristic themes in Japan, particularly with regard to the process of traveling to “other” locations within the domestic tourism industry. The article divides into three main parts that describe, analyze and discuss Amami Park, respectively through an ethnographic and critical lens.

Stress state and its anomaly observations in the vicinity of a fault in NanTroSEIZEExpedition 322

AbstractTo better understand the stress state and geological properties within the shallow Shikoku Basin, southwest of Japan, two sites, C0011A and C0011B, were drilled in open‐ocean sediments using Logging While Drilling (LWD) and coring, respectively. Resistivity image logging was performed at C0011A from sea floor to 950 m below sea floor (mbsf). At C0011B, the serial coring was obtained in order to determine physical properties from 340 to 880 mbsf. For the LWD images, a notable breakout anomaly was observed at a depth of 615 m. Using resistivity images and a stress polygon, the potential horizontal principal stress azimuth and its magnitude within the 500–750 mbsf section of the C0011A borehole were constrained. Borehole breakout azimuths were observed for the variation by the existence of a fault zone at a depth of 615 mbsf. Out of this fracture zone, the breakout azimuth was located at approximately 109° ± 12°, subparallel to the Nankai Trough convergence vector (300–315°). Our calculations describe a stress drop was determined based on the fracture geometry. A close 90° (73° ± 12°) rotation implied a 100% stress drop, defined as a maximum shear stress drop equal to 1 MPa. The magnitude of the horizontal principal stresses near the fracture stress anomaly ranged between 49 and 52 MPa, and the bearing to the vertical stress (Sv = 52 MPa) was found to be within the normal‐faulting stress regime. Low rock strength and a low stress level are necessary to satisfy the observations.

Why did People go up the Hill? Prehistoric Landscape Shifts and Neolithization of the Northern Ryukyu Archipelago, Japan

The remote Ryukyu archipelago, which runs from southern Japan southwest to Taiwan, is located in the subtropical zone, and consists of small coral and volcanic islands, with mainland Okinawa, the largest island, forming the main centre of settlement. Most of the islands are surrounded by coral reefs, beach sand dunes, and interior terraces lower than 700 m above mean sea level (amsl). Throughout human history, these geographical factors have conditioned the formation of cultural landscapes across the archipelago. Neolithic innovations and developments on these islands resulted in significant cultural landscape shifts, evidencing a unique Ryukyu trajectory of Neolithization that was quite different from those taking place elsewhere in the East Asian Inland Seas. In particular, major settlement and subsistence shifts on the islands mark the change from nomadic lifeways to increasing sedentism in the interior uplands between 4000 and 2500 BP, and a subsequent shift to lower coastal locations.

Calibrated Ages of Beachrock Samples Collected from the Miyako Islands, Okinawa, Southwest of Japan

Calibrated Ages of Beachrock Samples Collected from the Miyako Islands, Okinawa, Southwest of Japan

Granular experiments of thrust wedges: Insights relevant to methane hydrate exploration at the Nankai accretionary prism

The accumulation mechanism of methane hydrates has been a central issue in previous hydrate research regarding the Nankai accretionary prism, southwest of Japan. Expulsion of formation fluids is significant during the prism accretion process, and the migration of these methane-bearing fluids exerts a strong control on the accumulation of hydrates. Two types of fluid pathways, inter-granular porosity and faults, need to be evaluated to understand hydrate accumulation. Fluid migration along faults can be partly modeled by examining faulting activity. Our study modeled the accretion process by using two granular methods that approximated the geologic body as an assemblage of particles: (1) analog experiments using granular materials, and (2) a numerical simulation based on the distinct element method. The analog experiments closely reproduced the prism geometry observed in seismic profiles across the Nankai accretionary prism. Digital image correlation analysis indicated that the frontal thrust is generally active but older structures are also frequently reactivated. The numerical simulations produced prism geometries similar to those of the analog experiments. The velocity distributions of the particles showed evidence of episodic faulting and reactivation, but the internal stress field exhibited little change in the deeper part of the prism during deformation. The frequent and substantial changes in fault activity displayed by the models indicate episodic fluid flow along fault surfaces. Active frontal thrusting suggests that formation fluids generally migrate from deep within the prism to the deformation front, but may move along reactivated older faults. Inter-granular permeability also fluctuates, as it is controlled by temporal and spatial variations in the internal stress field. However, fluid flow is likely to be relatively stable in the deeper segment of the prism.

Mechanism of small vulcanian eruptions at Suwanosejima volcano, Japan, as inferred from precursor inflations and tremor signals

We examine precursory signals of vulcanian eruptions at Suwanosejima volcano, southwest of Japan, by deploying seismic and tilt stations close to the active crater to understand the shallow conduit processes just before explosions. Vulcanian eruptions at Suwanosejima for the period from October 2009 to 2011 are often preceded by a sudden cessation of continuous tremor associated with continuous ash emissions. The amplitude of continuous tremor decreases within about 10 s, and tilt signal starts to show uplift of the active crater. Then, the pause of continuous tremor and uplift continue for about 1–2 min, and tilt amplitudes reach a few tens of nanoradians at a distance of 400 m from the active crater. As the pause time of continuous tremor before explosion becomes longer, the maximum amplitude of explosion earthquake and uplift signal become larger. Vulcanian eruptions are also observed during periods without continuous tremor. In these cases, tilt signals capture uplifts of the active crater for about 10 min before explosions and reach a few tens of nanoradians. Cessations of volcanic gas emissions are observed before some explosions during periods without continuous tremor (Mori et al. 2011). These observations suggest that pressurization in the shallow conduit is caused by an accumulation of volcanic gases and ash through the formation of ‘cap’ in the conduit, possibly composed of stiffened magma due to degassing, cooling, rheological changes, or other mechanisms.

A Systematic Review for Estimation of HTLV-I Infection in the Blood Donors of Iran.

HTLV-I infection is a worldwide health problem and approximately 15–20 million persons are estimated to be infected with this infection (1). High HTLV-I seroprevalence rates in the general population or specific groups such as blood donors, have been reported from southwest of Japan, Caribbean basin, South America, Sub-Saharan Africa, and northeastern Iran (1,2). Although most infected people remain asymptomatic, the virus is associated with exceptionally severe diseases, such as adult T-cell leukemia/lymphoma (ATL), and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) (3). HTLV-I infection could transmit from mother to child, predominantly through breastfeeding, via sexual intercourse, and parenteral transmission by transfusion of infected cellular blood products or sharing of needles and syringes (1,4). Presence of HTLV-I infection was reported in 1990 among the Jews emigrated from Mashhad, northeast of Iran (5), and then some patients with ATL were indentified in Mashhad who were seropositive for HTLV-I (6). In later studies, the rate of HTLV-I infection in Mashhad was reported 3% in general population (7) and about 2% in blood donors (8) in 1996. There were some small to large scale epidemiological studies that have reported the prevalence of HTLV-I infection in blood donors from various regions of the country. The widest survey has been conducted by Rezvan et al. in 21 regional blood centres in 1996. This study reported a 0.29% rate for HTLV-I infection in total serum samples; 1.97% among Mashhadi blood donors, and zero to 0.5 percent in other centres (8). Moreover, later surveys in several regions of Iran reported different rates of the infection in blood donors. Nevertheless, there is no overall estimation of the infection in the country. This study conducted to accurately estimate the prevalence of HTLV-I infection in the Iranian blood donors through a comprehensive systematic review of literature and evidences.

Reproductive migration of the coconut crab Birgus latro

Knowledge of movement patterns is essential in tailoring spatial conservation and management measures. Although populations of the coconut crab, Birgus latro, have been severely depleted in most habitats, there have been few serious attempts to manage the resources. Recently, spatial conservation (e.g. seasonal area closure) has been suggested as an effective tool for resource management. However, relatively little is known about coconut crab movements, especially reproductive migration. To determine the dynamics of the reproductive migration of coconut crabs, we investigated both male and female migration patterns during the reproductive season in Hatoma Island, southwest of Japan. Both females and males migrated between inland and coastal areas during the reproductive season. Observed female seaward and landward migrations were temporally coincident with their reproductive activities (egg extrusion and larval hatching). Observed temporal-spatial distribution of males would be shaped by temporal variations in expected future mating opportunities within the reproductive season and male reproductive strategy in response to these variations.