Assessment of Fish Assemblages Before Dredging of the Shipping Channel Near the Mouth of the Savannah River in Coastal Georgia

Evaluating the effects of anthropogenic activities is dependent upon data collection prior to impact, though funds are rarely allocated to conduct an assessment before a critical need arises. The Savannah Harbor Expansion Project is one such activity that includes dredging of the Savannah River. It may potentially change physical conditions of the estuary thereby altering fish assemblages. The purpose of the present study was to characterize pre-impact fish assemblages along a salinity gradient near the mouth of the river and determine which abiotic factors most influence them. One site within the mouth of the Savannah River and two sites immediately outside the river mouth were sampled monthly for 2 years using both a beam trawl and seine net. Salinity, temperature, dissolved oxygen, and sediment grain size were assessed. All four factors had a significant effect on fish assemblages. A total of 3943 fishes representing ≥55 species formed three statistically distinct fish assemblages and at least three seasonal assemblages. Only 24 species (43.6 %) were collected by both gear types indicating the importance of using multiple gear types to assess fish assemblages. We conclude that the fish assemblages near the mouth of the Savannah River may be altered or may shift given the predicted increase in salinity and/or the possible changes in sediment composition from channel dredging. Understanding the abiotic factors that most influence spatial and seasonal fish distributions prior to dredging will be invaluable in predicting how organisms will be impacted by similar public projects elsewhere.     

Time-dependent reliability analysis for radionuclide migration in groundwater in near surface disposal facility using the enhanced Monte Carlo method

In the present study, reliability analysis of near surface disposal facility is performed, by assessing the probability of sequential failure of the multi barrier system using the contaminant transport model. The concentration and dose rate of the radionuclide evolve with time hence there is a need for time dependent reliability analysis. Due to the low values of expected probabilities of failure, an enhanced Monte Carlo (EMC) method and Subset simulation is employed. The Result of the analysis show that, the EMC method is useful to evaluate the probability of failure associated with the barrier system which has low probability of failure.     

Trans-Tasman migration: New Zealanders' explanations for their move

Abstract:  This study investigates why New Zealanders move to Australia. A survey of New Zealanders living in Australia found 'pull' factors, notably greater opportunities and better climate, were the most common reasons. While desire for change or sense of adventure was important, dissatisfaction with life in New Zealand was also a factor. Results indicated a form of transnationalism as migrants felt at home in both countries. They maintained links with New Zealand evident in support for New Zealand sporting teams, expressions of New Zealand nationality, emotional connection and regular contact with New Zealand.     

Devensian Late-glacial environmental change in the Gordano Valley, North Somerset, England: a rare archive for southwest Britain

The Late-glacial and Holocene environmental history of the Gordano Valley, North Somerset, UK has been reconstructed using pollen, sediment particle size and mineralogical analyses and radiocarbon dating. A Devensian sediment ridge across the valley confined the waters of a small lake, within which the initial sedimentation was minerogenic. Radiocarbon dating of overlying organic-rich deposits suggests that this began late in the Dimlington Stadial c. 18,000–15,000 Cal. BP. Petrographic analyses indicate the minerogenic sediments were partly wind-blown in origin. Climatic amelioration during the Windermere Interstadial c. 15,000 Cal. BP encouraged a shift from minerogenic to biogenic sedimentation. A brief return to minerogenic sedimentation between c. 10,400 and c. 9,520 Cal. BP was followed by uninterrupted fen peat accumulation throughout the Holocene. The later minerogenic horizon appears to represent the Loch Lomond Stadial. Few stratigraphic sequences preserving the complete Devensian Late-glacial–Holocene transition exist in southwest Britain, making the sedimentary archive of the Gordano Valley valuable regionally for reconstructing Late-glacial climate change.     

Marginalisation and demographic change in the semi-arid Karoo, South Africa

Semi-arid areas are often considered to be environmentally and economically marginal, a situation which has been exacerbated by economic change, shifts in agricultural production and land use, and changing state policy. These themes are explored with reference to a semi-arid landscape, namely the Karoo, which covers some 40% of the geographic space of South Africa and is used primarily for extensive livestock farming. Despite long-term decline in agricultural output, the traditional mainstay of the region, and weakening small town economies, the Karoo's population and the economies of its largest service centres are growing. There are, real socio-economic needs and development backlogs, and the situation has been exacerbated by recent political marginalisation. In this study, the small towns of the region are focal points of investigation and provide a lens to investigate the changing demographic and economic dynamics of the Karoo. Most of the region's population lives in these centres which are service, collection, and distribution points for what traditionally has been an agriculture-based regional economy. This paper explores the concept of marginalisation with specific reference to historical, economic, and demographic change.     

A Karst Connection model for Grand Canyon, Arizona, USA

Along the Asturian coast of northern Spain an uplifted wave-cut platform extends for  100 km east–west. The steep cliff which bounds the gently seaward-dipping platform to the north increases in height from 30 m in the west to 100 m in the east and reflects the overall eastward increase in platform elevation. The southern edge of the 2–4 km-wide platform runs along the foothills of the Cantabrian Mountains, as constrained by a high-resolution digital elevation model. The marine platform, which was carved into deformed Paleozoic bedrock with abundant quartzite beds, is largely covered by weathered marine and continental sediments. Quartzite samples from flat bedrock outcrops which are currently not covered by sediment or soil yield cosmogenic nuclide concentrations (²¹Ne, ¹⁰Be and ²⁶Al) that demonstrate a long and complex exposure history, including periods of burial with partial or complete shielding from cosmic rays. The combination of multiple cosmogenic nuclides yields a minimum age of 1–2 Ma for the platform. Taking into account (i) the horizontal and vertical extent of the platform, (ii) the high resistance to erosion of the quartzitic bedrock, and (iii) published data on the magnitude of past sea level fluctuations, we suggest that the wave-cut platform formed in the Pliocene. Subvertical faults cutting the platform at high angles to the coastline offset the southern edge of the platform by 20 to 40 m and reactivate the pre-existing anisotropy in the Paleozoic bedrock. Uplift and crustal deformation of the coastal region have occurred after platform formation in the Pliocene and may still be active. The slow deformation of the northern edge of the Iberian plate including the Cantabrian Mountains may result from the ongoing slow convergence at an incipient subduction zone extending along the coast of northern Spain.     

Overcoming disciplinary solitude: The archaeology and geology of native copper in Eastern North America

Although native copper has attracted the scholarly attention of both geologists and archaeologists since the middle of the 19th century, it is only recently that native copper studies have benefited from interdisciplinary research. This history of disciplinary solitude can be traced to the professionalization of the two fields in the early 20th century, an era in which crossdisciplinary communication began to wane. The effects of this phenomena resulted in the development of a model of aboriginal native copper procurement by archaeologists that did not take into account the geological literature, which had long identified numerous—rather than a single—source of native copper in North America. In this article, the author discusses how this disciplinary solitude developed and how it resulted in the creation of a dominant model for native copper procurement that constrained our understanding of aboriginal lifeways for generations. The author also considers how increasing collaboration between geologists and archaeologists since the 1970s has led to the reevaluation of an old model of native copper procurement that has been uncritically accepted by most archaeologists for over a century and a half. © 2007 Wiley Periodicals, Inc.     

Trace‐element analysis of native copper: The view from Northern Minnesota,USA

Native copper, both finished artifacts and worked pieces, are relatively common in pre‐Contact sites of northeastern Minnesota. Fifteen artifact samples and seven sources of native copper were submitted for trace‐element analysis as a test of the procedures developed by G. Rapp, Jr. and colleagues (2000). Although the specific sources chosen had high typicality probabilities, very low posterior probabilities preclude confidence that the artifacts were accurately sourced. Potential problems include incomplete characterization of several sources, as well as the limited number of sources in the database. Of more interest than identification of specific sources is the selection of apparent source pairs. Michipicoten (eastern Lake Superior) and Isle Royale (western Lake Superior) are often chosen together; Weyerhauser Mine (Wisconsin) and the Champion Mine (Keewenaw Peninsula) may form another pair. Future research should concentrate on identifying patterns of sources in the region rather than focusing on specific mines. © 2007 Wiley Periodicals, Inc.     

A digital procedure for ground water recharge and discharge pattern recognition and rate estimation

A digital procedure to estimate recharge/discharge rates that requires relatively short preparation time and uses readily available data was applied to a setting in central Wisconsin. The method requires only measurements of the water table, fluxes such as stream baseflows, bottom of the system, and hydraulic conductivity to delineate approximate recharge/discharge zones and to estimate rates. The method uses interpolation of the water table surface, recharge/discharge mapping, pattern recognition, and a parameter estimation model. The surface interpolator used is based on the theory of radial basis functions with thin-plate splines. The recharge/discharge mapping is based on a mass-balance calculation performed using MODFLOW. The results of the recharge/discharge mapping are critically dependent on the accuracy of the water table interpolation and the accuracy and number of water table measurements. The recharge pattern recognition is performed with the help of a graphical user interface (GUI) program based on several algorithms used in image processing. Pattern recognition is needed to identify the recharge/discharge zonations and zone the results of the mapping method. The parameter estimation program UCODE calculates the parameter values that provide a best fit between simulated heads and flows and calibration head-and-flow targets. A model of the Buena Vista Ground Water Basin in the Central Sand Plains of Wisconsin is used to demonstrate the procedure.