Testing the sediment-trapping paradigm of seagrass: Do seagrasses influence nutrient status and sediment structure in tropical intertidal environments?

Seagrass meadows are considered important for sediment trapping and sediment stabilisation. Deposition of fine sediments and associated adsorbed nutrients is considered an important part of the chemical and biological processes attributed to seagrass communities. This paradigm was based on work in temperate regions on Zostera marina and in tropical regions on Thalassia testudinum, two species that maintain relatively high biomass, stable meadows. The current study investigates this concept for three species of intertidal tropical seagrass meadows in northeastern Australia. Sediment structure and nutrient status did not differ between vegetated and unvegated habitats in intertidal areas within the central region of the Great Barrier Reef World Heritage Area. The 'trapping' functions that have been attributed to seagrasses need to be re-assessed for a variety of locations and species before they can be accepted as dogma. In tropical Australia, intertidal meadows are predominantly ephemeral and comprised of structurally small species of low biomass. Consequently, sediment trapping within these meadows is largely insignificant

FURTHER IMPLICATION OF MURINE LEUKEMIA-LIKE VIRUS IN THE DISORDERS OF NZB MICE

Further evidence implicating murine leukemia-like virus in the disorders of NZB mice was afforded by a study of antigens associated with murine leukemia virus (MuLV). MuLV group antigens were prevalent in extracts of spleen, kidney, and, to a lesser extent, thymus throughout a substantial portion of the life span of NZB mice as well as in extracts of lymphomas and sarcomas indigenous to the strain. G (Gross) soluble antigen, type-specific antigen, was first detected in plasma of untreated NZB mice at 3 months of age. G soluble antigen production increased thereafter in line with age, with 50% of reactions becoming positive at 5.3 months and 100% at 7 to 9 months. From months 3 to 9, the time-response curve for positive conversion of direct antiglobulin (Coombs) tests in untreated NZB mice corresponded closely to that for G soluble antigen production. Beyond the 9th month, G soluble antigen underwent elimination from the plasma of NZB mice, with positive reactions reduced to 50% at 13.3 months and to 0% at 18 months. G natural antibody was first detected in the serum of NZB mice at about 10 months of age and increased thereafter in line with age. The curves for G antibody production and G soluble antigen elimination bore a reciprocal relation to each other with crossover at 50% response occurring at 13.3 months. Significant proteinuria, a functional manifestation of membranous glomerulonephritis, became increasingly prevalent in female NZB mice as G soluble antigen was eliminated from plasma. Cumulative mortality of female NZB mice, mainly attributable to renal glomerular disease, increased in phase with G antibody production. MuLV group antigens were identified in the glomerular lesions by the immunofluorescence method. Positive conversion of direct antiglobulin tests was significantly delayed by vaccinating baby NZB mice with formaldehyde-inactivated cell-free filtrates of older NZB mouse spleens. The plasmas of vaccinated NZB mice with negative direct antiglobulin reactions at 4 to 7 months were likewise negative when tested for G soluble antigen. The 50% response time for G antibody production in the vaccinated NZB mice occurred at 7.3 months, that is, 6 months earlier than in untreated NZB mice. The collective findings implicate murine leukemia-like virus in the etiology of autoimmune hemolytic disease and membranous glomerulonephritis, as well as malignant lymphoma, of NZB mice and suggest that virus-specified cell-surface and soluble antigen is a factor in the immunopathogenesis of the renal disease and possibly also the autoimmune hemolytic disease

Seagrasses between Cape York and Hervey Bay, Queensland, Australia

The area of seagrasses in waters adjacent to the Queensland coast between Cape York and Hervey Bay is approximately 4000 km2. Seagrasses were found near estuaries, in coastal bays and associated with islands, at sites that provided shelter from the south-easterly trade winds and Pacific Ocean swells. Of the seagrass meadows mapped, 37% had a bottom vegetation cover greater than 50%. Two large continuous areas (total of approximately 2500 km2) of seagrass of predominantly Halophila species were found in deep water in Hervey Bay and between Barrow Point and Lookout Point and may be part of a much larger area of deep-water seagrass habitat not yet surveyed in the Great Barrier Reef province. Fourteen seagrass species were found in the surveyed region, and most were typical of the northern Australian and Indo-West Pacific region. The opportunistic Halophila and Halodule species were most common, with Halophila ovalis (R. Br.) Hook. f. and Halodule uninervis (Forsk.) Aschers. each being found in more than 15% of samples. High species richness occurred at depths of less than 6 m, predominantly in sheltered bays at coastal and island locations. Low species richness at estuary- associated sites may be due to stresses caused by low salinity during monsoonal runoff periods or exposure at low tides. Zostera capricorni Aschers. was restricted to these areas and may have a competitive advantage over other species with lesser tolerance to varying salinity. Species richness decreased with an increase in both latitude and depth. The latitudinal limits of recorded distributions for some of these tropical seagrasses were confirmed. Seagrass biomass decreased with increasing depth, but parameters of seagrass abundance showed no correlation with latitude, being dependent on a complex of site-related factors. High seagrass biomass occurred at sheltered sites, including estuary-associated, coastal-bay and island-associated sites. The maximum recorded above-ground biomass was 102.9 g m-2 for Zostera capricorni at Upstart Bay. Shoot densities reached 13 806 shoots m-2 for Halophila ovalis at Escape River, and the highest leaf area index was 1.81 for Zostera capricorni at Upstart Bay

INVESTIGATION OF CRUSTAL MOTION IN THE TIEN SHAN USING INSAR

The northern Tien Shan of Central Asia is an area of active mid-continent deformation. Although far from a plate boundary, this region has experienced 5 earthquakes larger than magnitude 7 in the past century and includes one event that may as be as large as Mw 8.0. Previous studies based on GPS measurements indicate on the order of 23 mm/yr of shortening across the entire Tien Shan and up to 15 mm/year in the northern Tien Shan (Figure 1). The seismic moment release rate appears comparable with the geodetic measured slip, at least to first order, suggesting that geodetic rates can be considered a proxy for accumulation rates of stress for seismic hazard estimation. Interferometric synthetic aperture radar may provide a means to make detailed spatial measurements and hence in identifying block boundaries and assisting in seismic hazard. Therefore, we hoped to define block boundaries by direct measurement and by identifying and resolving earthquake slip. Due to political instability in Kyrgzystan, the existing seismic network has not performed as well as required to precisely determine earthquake hypocenters in remote areas and hence InSAR is highly useful. In this paper we present the result of three earthquake studies and show that InSAR is useful for refining locations of teleseismically located earthquakes. ALOS PALSAR data is used to investigate crustal motion in the Tien Shan mountains of Central Asia. As part of the work, considerable software development was undertaken to process PALSAR data. This software has been made freely available. Two damaging earthquakes have been imaged in the Tien Shan and the locations provided by ALOS InSAR have helped to refine seismological velocity models. A third earthquake south of Kyrgyzstan was also imaged. The use of InSAR data and especially L band is therefore very useful in providing groundtruth for earthquake locations

Full moment tensor and source location inversion based on full waveform adjoint inversion: application at the Geysers geothermal field

Abstract not provide