The generation and preservation of multiple hurricane beds in the northern Gulf of Mexico

Cores collected from Mississippi Sound and the inner shelf of the northeast Gulf of Mexico have been examined using ²¹⁰Pb and ¹³⁷Cs geochronology, X-radiography, granulometry, and a multi-sensor core logger. The results indicate that widespread event layers were probably produced by an unnamed hurricane in 1947 and by Hurricane Camille in 1969. Physical and biological post-depositional processes have reworked the event layers, producing regional discontinuities and localized truncation, and resulting in an imperfect and biased record of sedimentary processes during the storms. The oceanographic and sedimentological processes that produced these event beds have been simulated using a suite of numerical models: (1) a parametric cyclone wind model; (2) the SWAN third-generation wave model; (3) the ADCIRC 2D finite-element hydrodynamic model; (4) the Princeton Ocean Model; (5) a coupled wave–current bottom boundary layer-sedimentation model; and (6) a model for bed preservation potential as a function of burial rate and bioturbation rate. Simulated cores from the Mississippi Sound region are consistent with the observed stratigraphy and geochronology on both the landward and seaward sides of the barrier islands.     

Observations of the Sediment-Water Interface: Marine and Fresh Water Environments

The sediment at the interface immediately beneath the water column is distinct from deeper-lying sediments in its properties and, at least quantitatively, in the processes driving diagenesis. Progress in understanding the sediment-water interface can be based on consideration of fundamentals of biogeochemical particle / fluid interactions and on application of certain biological techniques especially suited to this challenging portion of the sediment column. This article reports results achieved by combining theoretical fundamentals and specialized experimental techniques in the study of the interface from selected depositional environments. For fine-grained and sandy deposits from fresh-water to coastal marine environments, the interface is characterized by exaggerated microrelief, great porosity, and significant biological alteration. Additional application of this research approach is poised to further our understanding of engineering, and acoustic and xenochemical responses of sedimentary materials, with special emphasis on the influence of the bio-organic phase of the interface upon its fabric and physical properties.     

Geochemical and tectonic implications of igneous rocks from ODP leg 114, sub-antarctic South Atlantic

Igneous rocks recovered from three major tectonic features of the sub-antarctic South Atlantic Ocean during ODP Leg 114 have a range of compositions: Northeast Georgia Rise, basalt to andesite; Meteor Rise, basalt to trachyte; spreading center in the West South Atlantic Basin, MORB-like basalt. Major and trace element as well as Sr and Nd isotopic data clearly indicate that all rocks share the enriched elemental and isotopic signatures typical of both hotspot and mid-ocean ridge volcanism in the southern ocean basins. Data for the Northeast Georgia and Meteor Rises also suggest the influence of older, continental lithosphere.     

Secondary school student perspectives on community resilience in Grey District

For a national competition supported by the New Zealand Board of Geography Teachers, secondary school students in years 10–13 were asked to identify and investigate factors that were building community resilience in their home areas, and the entries provided young people's perspectives on how well individuals, families and communities ‘bounce back’, adapt, change and become stronger following an adverse event. This article concerns the findings of students at Greymouth High School. Their entries showed that community resilience in Grey District depended on individual and collective capacity for action. The greater their involvement in community affairs and projects, the more likely individuals and families were to form networks and participate in communal activities. In Greymouth, as elsewhere in New Zealand, membership of voluntary organisations and participation in planning for, and responding to, catastrophic events has helped residents respond effectively in times of adversity and has enhanced community resilience.     

Optical identifications of radio sources with accurate positions using the United Kingdom Schmidt Telescope (UKST) IIIA-J plates

Several programmes are making use of UKST Sky Survey plates to identify southern radio sources. The fine-grain modern plates and accurate radio positions give a much improved identification rate. It seems that it will very soon be possible to determine whether or not there is a quasar redshift cut-off at z4. There is an urgent need for more accurate fundamental reference star positions in the South.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Biogeographic variability in the physiological response of the cold‐water coral Lophelia pertusa to ocean acidification

While ocean acidification is a global issue, the severity of ecosystem effects is likely to vary considerably at regional scales. The lack of understanding of how biogeographically separated populations will respond to acidification hampers our ability to predict the future of vital ecosystems. Cold‐water corals are important drivers of biodiversity in ocean basins across the world and are considered one of the most vulnerable ecosystems to ocean acidification. We tested the short‐term physiological response of the cold‐water coral Lophelia pertusa to three pH treatments (pH = 7.9, 7.75 and 7.6) for Gulf of Mexico (USA) and Tisler Reef (Norway) populations, and found that reductions in seawater pH elicited contrasting responses. Gulf of Mexico corals exhibited reductions in net calcification, respiration and prey capture rates with decreasing pH. In contrast, Tisler Reef corals showed only slight reductions in net calcification rates under decreased pH conditions while significantly elevating respiration and capture rates. These differences are likely the result of environmental differences (depth, pH, food supply) between the two regions, invoking the potential for local adaptation or acclimatization to alter their response to global change. However, it is also possible that variations in the methodology used in the experiments contributed to the observed differences. Regardless, these results provide insights into the resilience of L. pertusa to ocean acidification as well as the potential influence of regional differences on the viability of species in future oceans.