Distribution and retention of Petrolisthes armatus in a coastal plain estuary: The role of vertical movement in larval transport

Since transport of planktonic larvae is essential to the maintenance and expansion of many marine species, we examined the spatial and temporal distribution of green porcelain crab Petrolisthes armatus (Gibbes, 1850) larvae and the possible underlying physical and behavioral mechanisms using a combination of field observations and numerical modeling. The field study consisted of observations of larval abundance and distribution as well as hydrographic surveys of the Satilla River estuary on the east coast of the USA in August 2006. Larvae were found throughout the water column within the tributaries but primarily at depth in the main river. A numerical model was used to examine the effect of flow and possible larval behavior responsible for the observed distribution and the consequences for larval retention in the estuary. Model results that included downward larval movement are consistent with the field observations, supporting the hypothesis that P. armatus larvae vertically migrate within the water column, which aids in their retention within the estuary.     

A 6000 year water level history of Europe Lake, Wisconsin, USA

Europe Lake occupies a small, closed, basin that would have been an embayment in Lake Michigan during the high water level events in the larger lake. Cores recovered from the lake reveal late Holocene water level fluctuations in the basin that are inferred from changes in taxa and abundance of molluscs, ostracodes, magnetic susceptibility, organic carbon, and oxygen isotopes.Non-glacial, Holocene lacustrine/paludal sedimentation in this portion of the Europe Lake basin started after 6600 RCYBP and was probably initiated by a rise in the water table of the deep bedrock aquifer, during the Nipissing transgression in Lake Michigan. Isotopically light ground water from this source was probably a major contributor during this phase to the negative ¹⁸O spikes in Valvata tricarinata and Amnicola limosa.The start of stable lacustrine conditions is marked by maximum diversity of ostracode and mollusc taxa and a shift toward much more positive ¹⁸O values. The Europe Lake basin at this time became an embayment of Lake Michigan. This event was probably coeval with the peak of the Nipissing transgression, when the water plane reached an altitude of about 183 m.The isolation of Europe Lake from Lake Michigan started at about 2390 RCYBP and is probably due to a drop in water level in Lake Michigan and/or to isostatic uplift of the Door Peninsula. Since isolation from Lake Michigan, water levels in Europe lake have been controlled primarily by fluctuations in local precipitation, evaporation and ground water discharge.     

The CO Cameron band emission in the Red Rectangle

The origin of the strong CO Cameron band emission in the Red Rectangle is investigated. From a comparison of laboratory spectroscopic data and astronomical observations in combination with chemical modelling, it is concluded that the Cameron band emission of CO originates from the dissociative recombination of HCO⁺, and its intensity provides a measure of the product of the density of HCO⁺ ions and the electron density, integrated along the line of sight.     

Tectonometamorphic Cycles in Different Geodynamic Conditions

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An analytic model for the epoch of halo creation

In this paper we describe the Bayesian link between the cosmological mass function and the distribution of times at which isolated haloes of a given mass exist. By assuming that clumps of dark matter undergo monotonic growth on the time-scales of interest, this distribution of times is also the distribution of 'creation' times of the haloes. This monotonic growth is an inevitable aspect of gravitational instability. The spherical top-hat collapse model is used to estimate the rate at which clumps of dark matter collapse. This gives the prior for the creation time given no information about halo mass. Applying Bayes' theorem then allows any mass function to be converted into a distribution of times at which haloes of a given mass are created. This general result covers both Gaussian and non-Gaussian models. We also demonstrate how the mass function and the creation time distribution can be combined to give a joint density function, and discuss the relation between the time distribution of major merger events and the formula calculated. Finally, we determine the creation time of haloes within three N -body simulations, and compare the link between the mass function and creation rate with the analytic theory.     

Chemical Composition and Geologic History of Saline Waters in Aux Vases and Cypress Formations, Illinois Basin

Seventy-six samples of formation waters were collected from oil wells producing from the Aux Vases or Cypress Formations in the Illinois Basin. Forty core samples of the reservoir rocks were also collected from the two formations. Analyses of the samples indicated that the total dissolved solids content (TDS) of the waters ranged from 43,300 to 151,400 mg/L, far exceeding the 35,400 mg/L of TDS found in typical seawater. Cl-Br relations suggested that high salinities in the Aux Vases and Cypress formation waters resulted from the evaporation of original seawater and subsequent mixing of the evaporated seawater with concentrated halite solutions. Mixing with the halite solutions increased Na and Cl concentrations and diluted the concentration of other ions in the formation waters. The elemental concentrations were influenced further by diagenetic reactions with silicate and carbonate minerals. Diagenetic signatures revealed by fluid chemistry and rock mineralogy delineated the water-rock interactions that took place in the Aux Vases and Cypress sandstones. Dissolution of K-feldspar released K into the solution, leading to the formation of authigenic illite and mixed-layered illite/smectite. Some Mg was removed from the solution by the formation of authigenic chlorite and dolomite. Dolomitization, calcite recrystallization, and contribution from clay minerals raised Sr levels significantly in the formation waters. The trend of increasing TDS of the saline formation waters with depth can be explained with density stratification. But, it is difficult to explain the combination of the increasing TDS and increasing Ca/Na ratio with depth without invoking the controversial 'ion filtration' mechanism.     

Seasonal Investigations of Dissolved Organic Carbon Dynamics in the Tamar Estuary, U.K.

A high temperature catalytic oxidation (HTCO) technique was used to measure dissolved organic carbon (DOC) during seasonal surveys of the Tamar Estuary, U.K. At the time of the programme, the field of DOC analysis had been plagued by numerous analytical difficulties. However, using thorough calibration of the analytical systems and the systematic analysis of an internal reference material, a valuable estuarine DOC data set was produced. The range of DOC concentrations observed (478–110 μM C) is consistent with the published data for riverine and coastal sea waters respectively. The Tamar Estuary is a freshwater DOC-dominated system, with strong correlation between lateral DOC distribution and salinity. However, mixing behaviour was not strictly conservative. During tidal cycle studies at a fixed station, DOC concentrations appeared to be uncoupled from salinity, and were inversely related to turbidity. It is concluded that tidally-induced resuspension of bottom sediments provided the dominant control mechanism for DOC concentration. The Tamar Estuary shows contrasting behaviour to the larger, more heavily impacted, Severn Estuary. Hence it is likely that the behaviour of DOC in estuaries cannot be classified as typical per se, but is a function of the natural and anthropogenic characteristics of the catchment and hydrology.     

The Environment Act 1995 and quiet enjoyment: implications for countryside recreation in the national parks of England and Wales, UK

Summary National parks in England and Wales have traditionally been seen as places of quiet, less hurried recreation. The phrase 'quiet enjoyment' was adopted to represent this notion, and this paper traces the policy-making process involved in attempting to conserve this view. The debate during the enactment of the Environment Act 1995 brought the use and meaning of the phrase to prominence; amongst other issues, the use of the phrase in tenancy law precluded its use in legislation. The loss of the phrase 'quiet enjoyment' could have prolonged effects on the way in which national parks are used for recreational purposes.     

The Effects of Probe-Induced Flow Distortion on Velocity Covariances: Field Observations

We carried out measurements to test a simple theory of the effect of probe-induced flow distortion on turbulence measurements. We used two three-component sonic anemometers mounted 1.8m apart at a height of 6.7 m. Behind one was a horizontal circular cylinder of radius 0.15 m and length 1.2 m, chosen to model two-dimensional probe-induced flow distortion in the limit where the scale of the turbulence is very large compared to the scale of the probe. The second sonic anemometer measured the undistorted flow. The measured flow-distortion effects on the Reynolds shearing stress and the variances of streamwise and vertical velocity agree well with the theory.