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21.
Dietary analysis of harbour seals (Phoca vitulina) from faecal samples and overlap with fisheries in Erimo,Japan 
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下载免费PDF全文 Tabitha C. Y. Hui Yuka Morita Yumi Kobayashi Yoko Mitani Kazushi Miyashita 《Marine Ecology》2017,38(3)
The number of harbour seals in Japan has been rebounding since protection began in the mid‐1980s. With the increase in seal numbers, increased conflict with fisheries has occurred through depredation and the belief that seals compete with fisheries for prey. However, competition can only be determined if the prey species and quantities seals consume over time are known. We studied the diet of harbour seals in Erimo, site of the largest population of harbour seals in Japan, from 2011 to 2012 and assessed the degree of prey overlap with local fisheries. We used both hard parts and DNA techniques to identify prey items in seal scats, and compared these results to local fisheries data. A total of 46 prey occurrences was detected by both methods, of which 17 matched between techniques at least to the family level. Hard parts methods identified five incidences of prey undetected by DNA methods in five scats (one incidence per scat). DNA methods identified 24 additional prey occurrences in 13 scats, for which no hard part evidence for that prey had been found. This more than doubled the total number of prey occurrences across the 15 scats compared. Overall, the most frequently occurring harbour seal prey were walleye pollock (Theragra chalcogramma), sculpins and snailfishes. In contrast, the top three groups targeted by fisheries were codfishes, salmon and invertebrates. Many species common in the harbour seal's diet such as snailfishes and blennies were not targeted by fisheries. Fishes such as greenlings, sculpins, rockfishes and Japanese anchovy (Engraulis japonicus) were common in the diet of harbour seals, but made up a very small proportion of fisheries catches in Erimo. The importance of other prey species varied between seasons. Sculpins, greenlings and forage fishes were the top three prey groups for harbour seals in spring by percent modified frequency of occurrence, whereas the most important target groups by percentage mass caught by fisheries were codfishes, cephalopods and other invertebrates. Sculpins and rockfishes remained as important prey items for harbour seals in summer and autumn, in addition to codfishes, snailfishes and blennies. In contrast, the main groups caught by fisheries in summer were other fishes, particularly Japanese amberjack (Seriola quinqueradiata) and various species of sharks and eels, and invertebrates. By autumn, Erimo fisheries had focussed on catching salmon. Salmon were taken by harbour seals as well during this period, but at a relatively lower frequency compared to other prey groups. The results of our study show that although harbour seals consumed several of the prey species targeted by fisheries, the relative importance of these species to seals and fisheries and the seasons in which they were targeted were different. 相似文献
22.
Toshio Kataoka Eiji Yunoki Mitsuo Shimizu Tadashige Mori Osamu Tsukamoto Yukitaka Ohashi Ken Sahashi Toshihiko Maitani Koh’ichi Miyashita Toru Iwata Yoko Fujikawa Akira Kudo Roger H. Shaw 《Boundary-Layer Meteorology》2001,101(2):131-156
Concentrations of radon 222Rn andair pollutants, meteorological parametersnear the surface and vertical profiles of meteorological elements were measured atUchio (Okayama City, Okayama Prefecture, Japan) 12 km north from the coast ofthe Inland Sea of Japan. In the nighttime, the 222Rn concentration increased in the case of weak winds, but did not increase as much in the case of moderate or strong winds, as had been expected. In the daytime, the 222Rn concentrationheld at a slightly higher than average level for the period from sunrise to about 1100 JST. It is considered that this phenomenon is due to a period of morning calm, that is, a transition period from land breeze to sea breeze.NO, which is sensitive to traffic volume,brought information concerning advection.Oxidant concentrations,which reflect the availability of sunlight,acted in the reverse manner to 222Rnconcentrations. Thus, a set of 222Rn and air pollutants could provide useful information regarding the local conditions of the atmospheric boundary layer. 相似文献
23.
A deep section of accretionary complex: Susunai Complex in Sakhalin Island, Northwest Pacific Margin
Gaku Kimura Masayuki Sakakibara Hisashi Ofuka Hideo Ishizuka Sumio Miyashita Makoto Okamura Olex A. Melinikov Vilera Lushchenko 《Island Arc》1992,1(1):166-175
Abstract A deep section of accretionary complex, the metamorphosed Susunai Complex, is observed on Sakhalin Is., Russia. High pressure part of pumpellyite-actinolite facies metavolcanics, metacherts and metapelites are well exposed and constitute a tectonic pile preserving primary structures related to underplating of the oceanic crust. Three stages of deformation, D1 through D3 , suggest successive deformation during subduction, underplating and exhumation of the complex. Oceanic material in the complex is more abundant than other well documented ancient accretionary complexes (e.g. the Shimanto Belt in southwest Japan and the Ghost Rocks Formation in Alaska), which were shallowly underplated. At Susunai, deep down-stepping of a décollément has scraped off the upper part of the oceanic crust, primarily the pillowed basalt horizon. This down-stepping results from crustal weakening as overpressured water is released from the fractured oceanic crust during metamorphism. 相似文献
24.
Petrology, geochemistry and paleogeographic reconstruction of the East Sulawesi Ophiolite, Indonesia
Ade Kadarusman Sumio Miyashita Shigenori Maruyama Christopher D. Parkinson Akira Ishikawa 《Tectonophysics》2004,392(1-4):55
The East Sulawesi Ophiolite (ESO) is tectonically dismembered and widely distributed in Central and East Sulawesi. It comprises, from base to top, residual mantle peridotite and mafic–ultramafic cumulate through layered to isotropic gabbro, to sheeted dolerites and basaltic volcanic rocks. Residual peridotite is dominantly spinel lherzolite intercalated with harzburgite and dunite. Ultramafic rocks from different locations display significant differences in rock composition and mineral. However, the clinopyroxene of peridotite displays REE pattern similarities with those of mid-ocean ridge (MOR) origin, rather than those of suprasubduction zone (SSZ) origin. The gabbroic unit consists of massive gabbro, layered gabbro, mafic and ultramafic cumulate and anorthosite. The observed crystallization sequence of gabbroic unit, which is olivine→(spinel)→plagioclase→clinopyroxene→(orthopyroxene)→(hornblende), and the mineral chemistry data indicate that the ESO gabbro has similarities with MOR setting.Major and trace element geochemistry of basalt and dolerite suggests MOR, oceanic plateau and minor SSZ origins. A possible oceanic plateau origin is supported by the following: (i) the 15-km thickness is comparable with the thickness of oceanic plateau rather than normal oceanic lithosphere; (ii) there are no or only minor olivine phenocrysts in the basalt; and (iii) predominance of aphyric texture in the basalts. The REE pattern of ESO basalt exhibits N-MORB-like signatures. However, a negative Nb anomaly in the trace element spider diagram may be attributed to mantle heterogeneity of an OPB source.The geochemical variations and disparities for both peridotite and basalt and the noncogenetic relationship between crust and mantle sections in several locations suggest that the ESO may have been formed at one tectonic setting and was later overprinted by magmatism in different environments through its birth to emplacement. A possible Cretaceous origin of an oceanic plateau component of the ESO is indicated on the basis of calculated paleopositions using plate trajectory analyses together with previously published paleolatitude data. The ESO can be traced back to the proximity of the presently active region of the SW Pacific Superplume. 相似文献
25.
K. Ichimoto B. Lites D. Elmore Y. Suematsu S. Tsuneta Y. Katsukawa T. Shimizu R. Shine T. Tarbell A. Title J. Kiyohara K. Shinoda G. Card A. Lecinski K. Streander M. Nakagiri M. Miyashita M. Noguchi C. Hoffmann T. Cruz 《Solar physics》2008,249(2):233-261
The Solar Optical Telescope (SOT) onboard Hinode aims to obtain vector magnetic fields on the Sun through precise spectropolarimetry of solar spectral lines with a spatial
resolution of 0.2 – 0.3 arcsec. A photometric accuracy of 10−3 is achieved and, after the polarization calibration, any artificial polarization from crosstalk among Stokes parameters is
required to be suppressed below the level of the statistical noise over the SOT’s field of view. This goal was achieved by
the highly optimized design of the SOT as a polarimeter, extensive analyses and testing of optical elements, and an end-to-end
calibration test of the entire system. In this paper we review both the approach adopted to realize the high-precision polarimeter
of the SOT and its final polarization characteristics. 相似文献
26.
Abstract An accretionary complex, which contains fragments of a remnant island arc, was newly recognized in the Cretaceous accretionary terranes in Hokkaido, Japan. It consists of volcanics, volcanic conglomerate, intermediate to ultramafic intrusive rocks with island-arc affinity including boninitic rocks, accompanied by chert and deformed terrigenous turbidites. Compared with the results of modern oceanic surveys, the preserved sequence from island-arc volcanics to chert, via reworked volcanics, is indicative of intraoceanic remnant arc, because the sequence suggests an inactive arc isolated within a pelagic environment before its accretion. The age of a subducting oceanic crust can be discontinuous before and after a remnant-arc subduction, resulting in abrupt changes in accretion style and metamorphism, as seen in Cretaceous Hokkaido. Subduction of such an intraoceanic remnant arc suggests that the subducted oceanic plate in the Cretaceous was not an extensive oceanic plate like the Izanagi and/or Kula Plates as previously believed by many authors, but a marginal basin plate having an arc–back-arc system like the present-day Philippine Sea Plate. 相似文献
27.
EPMA analyses and K-Ar age determinations were carried out on phengite in pelitic schist from the Sanbagawa metamorphic belt of the Kanto Mountains, Central Japan.
Phengite from the Sanbagawa pelitic schist in the Kanto Mountains generally occurs as aggregates of fine-grained crystals. It is extremely fine-grained in domains adjacent to relatively rigid garnet and albite porphyroblasts. This suggests that deformation-induced grain-size reduction took place in phengite during the ductile deformation accompanying the exhumation of the host schists. EPMA analysis shows that phengite is chemically heterogeneous at the thin-section scale, suggesting that it formed during retrograde metamorphism in restricted equilibrium domains. The retrograde chemical reaction was promoted by the ductile deformation.
K-Ar ages of phengite get younger from the Southern Unit (82 Ma) to the Northern Unit (58 Ma) in the Kanto Mountains. The age range is similar to that in Central Shikoku. The older schists occur in the higher metamorphic grade zone in Central Shikoku and in the lower-grade zone in the Kanto Mountains. The thermal structures in Central Shikoku are inverted, so that the highest-grade zone occurs in the upper or middle parts of the apparent stratigraphic succession. In contrast, the Kanto Mountains have a normal thermal structure: the higher-grade zone is in the lower part of the apparent stratigraphic succession. The different tectonic features in exhumation produced the two contrasting age-temperature-structure relations at the western side of Sanbagawa belt in Central Shikoku and the eastern end of the Sanbagawa belt in the Kanto Mountains that are 800 km distant from each other. Namely, the western Sanbagawa belt in Central Shikoku underwent longer ductile deformation during the exhumation than the eastern Sanbagawa belt in the Kanto Mountains. 相似文献
28.
Durair A'Shaikh Hiroharu Matsueda Toshio Mizuta Sumio Miyashita 《Resource Geology》2006,56(2):167-182
Abstract. The hydrothermal alteration in Ghuzayn Volcanics was associated with mineralization and accumulation of three massive sulfide deposits. The Ghuzayn Volcanics were discriminated into basaltic and andesitic lavas. The crossplots of Zr versus Nb, Y, Hf, La and Lu show that they fall in the same linear fractionation trends with more evolved affinities in the andesitic lavas compared to the less evolved affinities in the basaltic lavas. The immobile trace element contents of the Ghuzayn Volcanics show that they are of oceanic to continental tholeiitic affinity which fall in the fields of back‐arc basin basalt, N‐MORB and island arc tholeiite all meet and match with the field of the Lau‐Tonga back‐arc basin lavas. The ore‐body No. 2 is underlain by a zone of intense argillization and silicification which are so‐called alteration pipe as in some of the Cyprus‐type massive sulfide deposits. The alteration in the proximity of the ore‐body No. 2 is characterized by a zone of epidotization and slight silicification and sulfide disseminations, and surrounded by another zone of slight silicification and sulfide dissemination in the outermost rim around the ore‐body No. 2. The alteration zones in the proximity of the ore‐body No. 2 were divided into Zones I and II based on the abundance of the secondary minerals in the altered basaltic lavas. The Zone I is located in the most northern upper part of the ore‐body No. 2 and characterized by corrensite, saponite and prehnite. However, the Zone II is located in the southern part of the ore‐body No. 2 and characterized by chlorite and epidote. Both alteration zones were formed by different alteration stages. Stage 1 was formed by non to partly reacted fluids, to crystallize Mg‐chlorite and albite at temperatures ranging from 150 to 250d?C. Further, these fluids evolved with time and became Mg‐depleted, Si‐ and metal‐enriched to crystallize Fe2+‐chlorite, epidote, quartz and sulfides at temperatures ranging from 250 to 350d?C in stage 2. Later, these fluids were evolved again to be Mg‐ and Ca‐enriched in stage 3 to crystallize prehnite, laumontite, corrensite and saponite at temperatures ranging from 150 to 220d?C. Late zeolite and calcite have overgrown the previously crystallized phases and crosscutting veins along the altered basaltic lavas in stage 4. Finally, the lavas were cracked and refractured to facilitate penetration of seawater into deeper parts to heat up again and re‐leach the silica and metals in a new mineralizing event. 相似文献
29.
Takaya Iwasaki Keiji Adachi Takeo Moriya Hiroki Miyamachi Takeshi Matsushima Kaoru Miyashita Testsuya Takeda Takaaki Taira Tomoaki Yamada Kazuo Ohtake 《Tectonophysics》2004,388(1-4):59
The Hidaka Collision Zone (HCZ), central Hokkaido, Japan, is a good target for studies of crustal evolution and deformation processes associated with an arc–arc collision. The collision of the Kuril Arc (KA) with the Northeast Japan Arc (NJA), which started in the middle Miocene, is considered to be a controlling factor for the formation of the Hidaka Mountains, the westward obduction of middle/lower crustal rocks of the KA (the Hidaka Metamorphic Belt (HMB)) and the development of the foreland fold-and-thrust belt on the NJA side. The “Hokkaido Transect” project undertaken from 1998 to 2000 was a multidisciplinary effort intended to reveal structural heterogeneity across this collision zone by integrated geophysical/geological research including seismic refraction/reflection surveys and earthquake observations. An E–W trending 227 km-long refraction/wide-angle reflection profile found a complicated structural variation from the KA to the NJA across the HCZ. In the east of the HCZ, the hinterland region is covered with 4–4.5 km thick highly undulated Neogene sedimentary layers, beneath which two eastward dipping reflectors were imaged in a depth range of 10–25 km, probably representing the layer boundaries of the obducting middle/lower crust of the KA. The HMB crops out on the westward extension of these reflectors with relatively high Vp (>6.0 km/s) and Vp/Vs (>1.80) consistent with middle/lower crustal rocks. Beneath these reflectors, more flat and westward dipping reflector sequences are situated at the 25–27 km depth, forming a wedge-like geometry. This distribution pattern indicates that the KA crust has been delaminated into more than two segments under our profile. In the western part of the transect, the structure of the fold-and-thrust belt is characterized by a very thick (5–8 km) sedimentary package with a velocity of 2.5–4.8 km/s. This package exhibits one or two velocity reversals in Paleogene sedimentary layers, probably formed by imbrication associated with the collision process. From the horizontal distribution of these velocity reversals and other geophysical/geological data, the rate of crustal shortening in this area is estimated to be greater than 3–4 mm/year, which corresponds to 40–50% of the total convergence rate between the NJA and the Eurasian Plate. This means that the fold-and-thrust belt west of the HCZ is absorbing a large amount of crustal deformation associated with plate interaction across Hokkaido Island. 相似文献
30.
Mauro de Melo Júnior Leonardo K. Miyashita Naira J. Silva Salvador A. Gaeta Rubens M. Lopes 《Marine Ecology》2013,34(3):363-372
We investigated the reproductive biology of the planktonic harpacticoid copepod Euterpina acutifrons, including morphometric data, egg production rates (EPR) and viability, and weight‐specific egg production. Experiments were carried out during 1 year in an inner‐shelf area off Ubatuba (SE Brazil), a site seasonally influenced by bottom intrusions of the relatively cold and nutrient‐rich South Atlantic Central Water (SACW). We hypothesized that E. acutifrons attain higher reproductive rates when SACW penetrates in this region. Live females were incubated individually in cell culture plates during two periods of 24 h each, under controlled temperature and light conditions. Euterpina acutifrons carried on average 16.9 ± 6.9 eggs·sac?1, ranging between 10.8 ± 5.7 and 30.8 ± 7.4 eggs·sac?1. Estimated EPRs ranged from 6.3 ± 3.4 to 13.6 ± 4.2 eggs·female?1·day?1, with mean weight‐specific egg production rates of 0.06 ± 0.04 and 0.17 ± 0.08 per day. Euterpina acutifrons was not directly influenced by SACW intrusions, but body length and clutch size were positively related to temperature and chlorophyll content. Egg hatching time was clearly dependent on water temperature, as a 2 °C increase resulted in a decrease of 15 h in egg hatching time. This shows that even a small variation in temperature may considerably affect E. acutifrons population dynamics. Reproductive traits of this pelagic harpacticoid seem, therefore, to be controlled by the trade‐offs between increased food supply and the metabolic demands at low temperatures associated with SACW bottom intrusions toward this coastal area. 相似文献