Echinoderms and oil pollution: A potential stress assay using bacterial symbionts

Oil pollution is a problem in the North Sea. Important sources of oil pollution are spills and drill cutting. Echinoderms are a major component of the macrobenthos in the North Sea (and elsewhere). They tend to be very sensitive to various types of marine pollution. Many species of echinoderms contain symbiotic sub-cuticular bacteria (SCB). The response of Amphiura filiformis, A. chiajei and Ophiothrix fragilis, all of which contain SCB, to oil pollution was studied in laboratory experiments, mesocosms and in the field. Sublethal stress was monitored by examining changes in the tissue loading of SCB. When subjected to hydrocarbon insult, there was a decline in the number of SCB. The potential use of SCB abundance to detect sublethal stress is discussed.     

Numerical models of convection in the earth's mantle

Calculations on convection in Newtonian fluids at large Rayleigh numbers show behaviour in general agreement with geophysical observations. The calculated values of surface velocities, regional gravity and topographic anomalies all lie within the range of values found at the earth's surface. The sign of the gravity anomaly over rising fluid is positive because the gravitational effect of the surface deformation is greater than that of the density deficit. This result appears to agree with geophysical observations and should permit the flow within the mantle to be followed in some detail.     

Factors Inhibiting Local Government Engagement in Environmental Sustainability: case studies from rural Australia

The literature on local government management of the environment in Australia has been limited in that it has typically focused on the urban sphere. In contrast, this paper places rurality at the centre of its inquiry. It uses data from 15 case studies of rural local governments in Australia to identify the main factors that inhibit natural resource management by rural councils. These barriers mobilise around four key themes: capacity, commitment, co-ordination and community. While many of the issues raised in this study of non-urban shires have been described in previous research, the paper argues that the geographic location of the areas under investigation aggravates barriers to engaging sustainability initiatives. It is contended that rural local governments need to be resourced accordingly to ensure that natural resource management at the local government level in Australia is not compromised.     

Experimentally determined biomediated Sr partition coefficient for dolomite: Significance and implication for natural dolomite

Two strains of moderately halophilic bacteria were grown in aerobic culture experiments containing gel medium to determine the Sr partition coefficient between dolomite and the medium from which it precipitates at 15 to 45 °C. The results demonstrate that Sr incorporation in dolomite does occur not by the substitution of Ca, but rather by Mg. They also suggest that Sr partitioning between the culture medium and the minerals is better described by the Nernst equation (D_Sr^dol = Sr_dol/Sr_bmi), instead of the Henderson and Kracek equation (D_Sr^dol = (Sr/Ca)_dol/(Sr/Ca)_solution. The maximum value for D_Sr^dol occurs at 15 °C in cultures with and without sulfate, while the minimum values occur at 35 °C, where the bacteria exhibit optimal growth. For experiments at 25, 35 and 45 °C, we observed that D_Sr^dol values are greater in cultures with sulfate than in cultures without sulfate, whereas D_Sr^dol values are smaller in cultures with sulfate than in cultures without sulfate at 15 °C.Together, our observations suggest that D_Sr^dol is apparently related to microbial activity, temperature and sulfate concentration, regardless of the convention used to assess the D_Sr^dol. These results have implications for the interpretation of depositional environments of ancient dolomite. The results of our culture experiments show that higher Sr concentrations in ancient dolomite could reflect microbial mediated primary precipitation. In contrast, previous interpretations concluded that high Sr concentrations in ancient dolomites are an indication of secondary replacement of aragonite, which incorporates high Sr concentrations in its crystal lattice, reflecting a diagenetic process.     

Heuristic numerical and analytical models of the hydrologic controls over vertical solute transport in a domed peat bog,Jura Mountains,Switzerland

We report the results of numerical and analytical simulations to test the hypothesis that downward vertical flow of porewater from the crests of domed alpine and kettle bogs controls vertical porewater distributions of major solutes such as Ca and Mg. The domed Etang de la Gruère bog (EGr), Switzerland, characterized by a vertical downward gradient of 0·04 and stratified layers of peat, is chosen as a field site for the model calibration and evaluation. The middle 4‐m section of the 6·5 m thick bog peat is heavily humified and has a hydraulic conductivity of ～10^?5·6 cm s^?1. Above and below, peat is less humified with a hydraulic conductivity of ～10^?3 cm s^?1. Heuristic finite difference simulations, using Visual MODFLOW, of the bog hydraulics show that the higher conductivity peat at the bog base is critical to create the observed deep, local flow cells that substantively recharge porewater. Model results and Peclet number calculations show that before ～7000 ¹⁴C yr BP diffusion of solutes from underlying mineral soils controlled the vertical distribution of porewater chemistry. From 7000 to ～1250 ¹⁴C BP the porewater chemistry was probably controlled by both upward diffusion and downward advection, and after ～1250 ¹⁴C yr BP porewater chemistry was probably controlled by downward advection. Concentrations of conservative major solutes in the porewaters of alpine, ombrotrophic bogs are the net effect of both downward vertical porewater movement and upward vertical diffusion, the magnitudes of which are delicately poised to the configuration of the bog water table over time and subsurface peat stratigraphy. Copyright © 2002 John Wiley & Sons, Ltd.     

Emerging trends in state regulation of private communities in the U.S.

Common interest housing (CIDs), which includes nearly all gated communities as well as non-gated but privately governed neighbourhoods, has become the predominant form of new housing construction in America. Optimistic early assessments that CIDs would prove to be more efficient alternative to municipalities are confronted by the fact of high levels of conflict and litigation, which are proving costly to residents as well as local governments. These conflicts are often highly publicized in the press, leading to concerns in the real estate industry that the demand for such housing could be jeopardized. The conflicts arise from having unpaid, untrained volunteer directors carrying out what were once municipal government functions, and concern financial issues as well as alleged abuses of power by association boards. In response to some of these concerns, across the nation, small but vocal ant-HOA owners groups are organizing, using the internet as their medium and gaining attention from the press. A consensus is emerging that the law governing private communities needs major changes, and different approaches are proposed or being implemented in several states. This paper examines these emerging regulatory trends and offers an assessment of their prospects.     

Residency and migratory behaviour by adult Pomatomus saltatrix in a South African coastal embayment

Acoustic telemetry was used to study patterns of habitat use and movements of Pomatomus saltatrix L. (common name elf/shad/bluefish/tailor) within the Saldanha Bay with Langebaan Lagoon coastal embayment on the west coast of South Africa. Thirty six mature P. saltatrix were tagged with acoustic transmitters and released within the lagoon in May 2006 and November–December 2007, and their positions were monitored until late-November 2008 using 28 hydrophones positioned throughout the embayment. The detection pattern of P. saltatrix suggested a tendency to residence within the embayment throughout the thirty month long study period, with nearly 60% of released individuals only being detected within the lagoon in the inner part of the embayment. However, there was a long-term trend of movement from the lagoon into the bay. One individual was recaptured off the east coast of South Africa 21 months after being tagged, 1760 km away, suggesting that P. saltatrix are capable of undertaking long along-shore migrations. Over finer scales within the inner lagoon, P. saltatrix ground speed increased (1) with an increase in tidal current speed, (2) with an increase in photoperiod, and (3) during day. Pomatomus saltatrix tended to move seaward during ebb tides, and to occupy greater depths during day.     

The relationship between the geometry of normal faults and that of the sedimentary layers in their hanging walls

We derive an analytical expression that relates the shape of a fault in cross-section to the shape of the bedding horizons in its hanging wall block. The expression assumes that the hanging wall deforms by simple shear and that the footwall remains undeformed throughout. Although this paper concentrates on normal faults, the expression is equally valid and applicable to thrust faults. The direction of simple shear in the hanging wall block is arbitrary and has a dramatic effect on the predicted fault or bedding geometry. There is no reason to believe that the simple shear occurs on vertical planes, as is commonly assumed in graphical approaches to this problem, and ignoring the presence of inclined simple shear is likely to lead to considerable underestimates of the amount of extension across normal faults and in the amount of shortening across thrusts. Similar though more complicated expressions can be obtained when compaction within the hanging wall block is taken into account. For a planar normal fault such compaction may result in the development of a hanging wall syncline.