Use of colloidal iron as a tracer to measure the ingestion rates of free-living marine nematodes

Ingestion rates of free-living marine nematodes were measured using colloidal iron as a tracer. Detritus labeled with colloidal iron was fed to the dominant nematode species and cultured. The iron ingested by the animals was quantified using a scanning electron microscope equipped with differential X-ray energy analyzer (EDX). Average ingestion rates (μgC ind.⁻¹day⁻¹) measured were 0.28 for Symplocostoma sp., 0.29 for Polygastrophora sp., 0.73 for Mesacanthion sp. and 0.15 for Metachromadora sp. These values were higher than the values determined using radioactive organic materials as tracers, though the present method is considered to provide conservative values. This result thus strongly suggests that the ingestion rates of nematodes measured so far were underestimated, and the use of colloidal iron has advantages over the use of radioactive organic matter as a tracer.     

Seasonal Patterns of Vertical Distribution between Meiofaunal Groups in Relation to Phytodetritus Deposition in the Bathyal Sagami Bay, Central Japan

Temporal changes in the vertical distribution of metazoan meiofaunal groups were examined at a bathyal site (depth 1450 m) in Sagami Bay from December 1996 to August 1998. Among major meiofaunal groups, the vertical distributions of copepods (adults and copepodites), and kinorhynchs changed seasonally and they concentrated in the shallower part in the sediment profile when CPE concentrations were higher. Seasonal changes in the vertical distributions of ovigerous females and nauplii of copepods were not related to CPE concentrations, but related to that of total copepods. On the other hand, nematodes, ostracods, and polychaetes did not show seasonal migrations. These results suggest that there is a difference in the response to the sedimentation of organic matter between metazoan meiofaunal taxa.     

Paleomagnetism of Cretaceous Red beds from Eastern Part of South China Block

INTRODUCTIONCollisionofIndiawithAsiaappearstohavebroughtaboutlargetectonicdeformationofAsia,especiallyEastAsia(Tapponnieretal.,1986).Post-Cretaceousdeformation(translationand/orrotation)ofSimaoandIndochinablocks,whicharelocatedatthesouthernsideofRedRiverfault(RRF),hasbeenreportedfromCretaceouspaleomagneticin-vestigations(Yangetal.,l995;HuangandOpdyke,l993IYangandBesse,1993).AlsoinSouthChinablock(SCB)locatedatnorthsideoftheRRF,localdeformationofsomeregionsneartheRRFhasbeendocum…     

Frequency selective surfaces for radio astronomy

Frequency selective surfaces (FSSs) with the Jerusalem-cross array configuration have been developed for simultaneous observations of radio astronomical sources at the 40GHz and 80GHz bands. For supporting material, PET(polyethylene terephthalate: 200×220mm large, 12m thick, permittivity 3.0) was used, and copper was used for the conducting array. The measured characteristics were in good agreement with the calculated ones. The fabricated FSS has low insertion losses of less than 0.2dB and little distortion of polarization for each band. The characteristics of the developed FSS satisfy radio astronomical requirements.     

A simple fractionation method for determination of phosphorus components in phytoplankton: Application to natural populations of phytoplankton in summer surface waters of Tokyo Bay

A simple procedure for fractionation of phosphorus components in natural populations of phytoplankton has been developed. By a combination of a trichloroacetic acid (TCA) extraction, a hot dilute acid treatment, a charcoal treatment and an organic solvent extraction, cellular phosphorus was divided into orthophosphate, nucleotide phosphorus, sugar phosphates, acid-soluble polyphosphates, lipid phosphorus, nucleic acid phosphorus, acid-insoluble polyphosphates, and residual phosphorus. The recovery of phosphorus was 94±5%. This technique was applied to natural populations of phytoplankton in summer surface waters of Tokyo Bay. Nucleic acid phosphorus and orthophosphate were most abundant, and accounted for 30 to 50% of total phytoplankton phosphorus. The nucleic acid phosphorus was proportional to the biomass of phytoplankton, irrespective of ambient nutrient concentrations. The orthophosphate showed the largest change in association with the change in cellular phosphorus content as well as in ambient phosphate. The orthophosphate serves as a phosphorus reserve in the natural populations of phytoplankton in summer surface waters of Tokyo Bay whereSkeletonema costatum was dominant. Acid-insoluble polyphosphates tended to increase when ambient concentration of phosphate was high, but their amounts were almost one order of magnitude lower than that of orthophosphate.     

Phylogeny of transfer RNA and origins of organelles

By using nucleotide sequences of transfer RNA's, the endosymbiotic model for the origin of chloroplasts and mitochondria is examined. The endosymbiotic origin of the chloroplasts is confirmed, but concerning the origin of the mitochondria no conclusion can be drawn. Phyletic relations of euglenoids to higher plants and to animals are also discussed. Finally, phylogeny of fungi is discussed in terms of tRNA sequences and it is proposed that the classical taxonomy of fungi should be reconsidered in terms of molecular taxonomy or molecular paleontology.     

Comparison of carbon cycle between the western Pacific subarctic and subtropical time-series stations: highlights of the K2S1 project

A comparative study of ecosystems and biogeochemistry at time-series stations in the subarctic gyre (K2) and subtropical region (S1) of the western North Pacific Ocean (K2S1 project) was conducted between 2010 and 2013 to collect essential data about the ecosystem and biological pump in each area and to provide a baseline of information for predicting changes in biologically mediated material cycles in the future. From seasonal chemical and biological observations, general oceanographic settings were verified and annual carbon budgets at both stations were determined. Annual mean of phytoplankton biomass and primary productivity at the oligotrophic station S1 were comparable to that at the eutrophic station K2. Based on chemical/physical observations and numerical simulations, the likely “missing nutrient source” was suggested to include regeneration, meso-scale eddy driven upwelling, meteorological events, and eolian inputs in addition to winter vertical mixing. Time-series observation of carbonate chemistry revealed that ocean acidification (OA) was ongoing at both stations, and that the rate of OA was faster at S1 than at K2 although OA at K2 is more critical for calcifying organisms.     

A new mothed of classifying the growth form of corals and its application to a field survey of coral-associated animals in Kabira Cove,Ishigaki Island

In order to classify the growth form of corals, the following “growth form index” was defined to denote coral shape objectively: Growth Form Index=Coral Surface Area/ (Coral Wet Weight)^2/3. On the basis of this index, growth forms of corals were classified into four major forms: massive, irregular shaped, branching, and highly branching. Coral-associated animals were classified into four groups according to their mode of living: freeliving epi-, sessile epi-, boring crypto-, and secondary crypto-bionts. For the quantitative study of the distribution of coral-associated animals in each growth form of coral and in each habitat of the study area, living coral heads were collected using SCUBA from 10 stations representing various habitats in Kabira Cove, Ishigaki Island, Yaéyama Group, Okinawa Prefecture. By comparing the proportions of four life forms of animals associated with each of the four different growth forms of corals at each station, some consistent patterns were found: massive corals were dominated by both boring and secondary cryptobionts, while branching and highly branching corals were dominated by free-living and sessile epibionts. In addition, the absolute numbers as well as the proportions of the four life forms of animals associated with a given growth form of coral changed from the outer-reef outside the bay to the bay head. From these various distribution patterns, it became clear that the growth forms of corals have a strong influence on the micro ecological distribution of coral-associated animals at each station, while the physical environment regulates the distribution of these animals in a given locality on the macroscopic scale.     

In situ stress measurements in NIED boreholes in and around the fault zone near the 1995 Hyogo-ken Nanbu earthquake, Japan

Abstract The 1995 Hyogo-ken Nanbu (Kobe) earthquake, M 7.2, occurred along the north-east–south-west trending Rokko–Awaji Fault system. Three boreholes of 1001 m, 1313 m and 1838 m deep were drilled in the vicinity of the epicenter of the earthquake. Each borehole is located at characteristic sites in relation to active faults and the aftershock distribution. In particular, the Nojima–Hirabayashi borehole [Hirabayashi National Research Institute for Earth Science and Disaster Prevention (NIED) drilling] in Awaji Island was drilled to a depth of 1838 m, approximately 320 m southeast from the surface rupture of the Nojima Fault, and it crosses fracture zones below a depth of 1140 m. In situ stress measurements by the hydraulic fracturing method were conducted in these boreholes within 1.5 years after the earthquake. Measurement results suggest the following: (i) Differential stress values are very small, approximately 10 MPa at a depth of 1000 m at each site; (ii) the orientation of maximum horizontal compression is almost the same in the boreholes, perpendicular to the surface trace of the faults, north-west–south-east; (iii) fault types estimated from the state of stress differ among these sites; and (iv) the differential stress value just beneath the fault fracture zone decreases abruptly to one-half of that above the fault zone in the Hirabayashi NIED drilling. These features support the idea that the shear stress along the Rokko–Awaji Fault system decreased to a low level just after the earthquake.