Preliminary Analysis of the Temporal Patterns of Heavy Rainfall across the Southeastern United States

This paper examines trends in heavy rainfall events across the southeastern United States over the past century. Time series of the number of annual storm events over a 76.2 mm threshold were used for analysis. Significant trends that had some spatial coherence were identified. Increasing trends were detected in a region extending from northeastern Texas to the Appalachians, with a weaker signal of decreasing events along the East Coast. These patterns may be linked to fluctuations in the strength and migration of the Bermuda High.     

From small scales to the big picture: persistence mechanisms of planktonic grazers in the oligotrophic ocean

In this review we evaluate whether universal behavioral and metabolic mechanisms exist, which permit marine proto‐ and metazooplankton to persist in continuously food‐limited environments such as the North Pacific Subtropical Gyre and other oligotrophic ocean systems. We re‐visit the issue of what processes account for low steady‐state abundance of the dominant groups of planktonic grazers: phagotrophic protists and copepods, by examining evidence for the four processes proposed by Strom et al. (2000) : grazing thresholds, behavioral response to prey patchiness, top–down control of grazers, and mixotrophy (combination of photosynthesis and phagotrophy in protists) and/or omnivory (switching between alternate prey types). Published observations reveal that grazing thresholds, below which feeders reduce their feeding efforts and, with that, their metabolic expenditures, do exist. There are also studies suggesting that both protistan and small metazoan plankton feeders may take advantage of patchiness of food particles and are frequently mixotrophic and/or omnivorous. Predator patchiness in response to prey patches may facilitate top–down control of grazers. Finally, we discuss processes, which may lead to low quasi steady‐state abundances of food particles and feeders.     

Fish stocks and their management: The changing face of fisheries in South Africa

Transformation of South African marine fisheries over the past 10 years has had to balance economic stability, equity and sustainability. This is being done in three ways. First, access rights have been redistributed, increasing the number of rights holders 20-fold and the participation of historically disadvantaged individuals from 0.75% to 62%. Second, established companies have undergone internal transformation. Third, subsistence fishers have formally been recognised. New focuses include co-management, ecosystem-based management and marine protected areas. Further necessary steps include parity in salaries, attention to artisanal fishers, embracement of co-management, expansion of subsistence management and effective enforcement. Most stocks are healthy or recovering but exceptions, such as abalone, warn how quickly stocks can be decimated if co-operation is not achieved.     

Climate change: A looming challenge for fisheries management in southern Africa

It is now widely accepted that the earth's climate is changing under the influence of anthropogenic activities. A number of key changes in the earths atmosphere and ocean have already been detected (including increasing global surface temperature, rising sea levels, increases in incident UV radiation, changes in average annual precipitation, and increases in the variability and intensity of extreme weather events, among others), while speculation regarding future changes is rife. The implications of global climate change for fish stocks and fisheries is of concern to many scientists, but little effort has been made to incorporate observed changes or event such thinking into management models and paradigms. This paper summarises available evidence linking the production of key greenhouse gases with observed and future projected changes in the earth's climate, specifically in respect of a number of key atmospheric and oceanographic parameters likely to affect fish stocks in South Africa (temperature, pressure/wind fields, CO₂ concentration, rainfall, mean sea level and UV radiation). It also explores likely effects of these changes on fish stocks and key fishery sectors. In addition, it highlights a number of positive steps that be taken by management authorities to ensure that they and the fishing communities for which they are responsible are in the best possible position to deal with the effects of changing global climate as they become manifest.     

Groundwater monitoring for cement kiln dust disposal units in karst aquifers

Well-developed karst aquifers tend to be heterogeneous and consist of variable porosities. Groundwater monitoring and the associated data interpretations in such aquifers are often more complicated than porous medium aquifers. Collection of representative data in karst aquifers often requires monitoring at appropriately located wells and/or springs that are proven to connect to the groundwater system. Water samples are to be collected under different flow conditions, including base flow, high-flow, and low-flow. The sampling frequencies may vary from several months for base flows to minutes in response to recharge events. The groundwater monitoring program presented in this paper is for a cement kiln dust mono-fill site in a karst area of southern Indiana. Following dye tracing and extensive geophysical investigations, one spring was selected as a monitoring location. A second spring should be used as a monitoring location when the last cell of the mono-fill begins receiving the wastes. The paper discusses results from the first spring, at which nine background sampling events were completed to evaluate the natural variations of the water quality. Based on the background data, a statistical evaluation plan was developed for 12 water-quality parameters to determine the integrity of the landfill. The statistical power of the statistical analyses was evaluated by Monte Carlo simulations.     

Major and trace element provenance signatures in stream sediments from the Kando River, San'in district, southwest Japan

Abstract Basement rocks in the catchment of the Kando River in southwest Japan can be divided into two main groups. Paleogene to Cretaceous felsic granitoids and volcanic rocks dominate in the upstream section, and more mafic, mostly Miocene volcanic and volcaniclastic rocks occur in the downstream reaches. Geochemically distinctive Mount Sambe adakitic volcanic products also crop out in the west. X‐ray fluorescence analyses of major elements and 14 trace elements were made of two size fractions (<180 and 180–2000 µm) from 86 stream sediments collected within the catchment, to examine contrasts in composition between the fractions as a result of sorting and varying source lithotype. The <180 µm fractions are depleted in SiO₂ and enriched in most other major and trace elements relative to the 180–2000 µm fractions. Na₂O, K₂O, Ba, Rb and Sr are either depleted relative to the 180–2000 µm fractions, or show little contrast in abundance. Sediments from granitoid‐dominated catchments are distinguished by greater K₂O, Th, Rb, Ba and Nb than those derived from the Miocene volcanic rocks. Granitoid‐derived <180 µm fractions are also enriched in Zr, Ce and Y. Sediments derived from the Miocene volcanic rocks generally contain greater TiO₂, Fe₂O₃*, Sc, V, MgO and P₂O₅, reflecting their more mafic source. Sediments containing Sambe volcanic rocks in their source are marked by higher Sr, CaO, Na₂O and lower Y, reflecting an adakitic signature that persists into the lower main channel, where compositions become less variable as the bedload is homogenized. Normalization against source averages shows that compositions of the 180–2000 µm fractions are less fractionated from their parents than are the <180 µm fractions, which are enriched for some elements. Contrast between the size fractions is greatest for the granitoid‐derived sediments. Weathering indices of the sediments are relatively low, indicating source weathering is moderate, and typical of temperate climates. Some zircon concentration has occurred in granitoid‐derived <180 µm fractions relative to 180–2000 µm counterparts, but Th/Sc and Zr/Sc ratios overall closely reflect both provenance and homogenization in the lower reaches.     

Precipitation in the Venezuelan Andes in the context of regional climate

Summary Rainfall regimes are primarily unimodal in central and eastern Venezuela but bimodal (peaks in May–June and September-October-November with a minimum in July–August) in the northwest. There is a sharp transition across the Andes suggesting a topographic-circulation connection. However, a mid-summer minimum also occurs at other locations in Venezuela and Central America during individual years. This paper addresses the nature and control of the regimes including the role of large-scale circulation features and convection as indicated by outgoing longwave radiation data. Altitudinal characteristics of precipitation in the Andes and their spatial variability are also investigated. The development of the minimum within the rainy season annual cycle is shown to be related to the combined effects of the evolution of sea surface temperatures in the east Pacific warm pool and reinforced in the area of the Andes by enhanced easterlies during July and August.Abbreviations used in text ENSO El Nino-Southern Oscillation - EPWP East Pacific Warm Pool - ITCZ Inter-tropical Convergence Zone - MEI Multivariate ENSO Index - MSM Mid-Summer Minimum - NCEP National Centers for Environmental Prediction - OLR Outgoing Longwave Radiation - SOI Southern Oscillation Index - SST Sea Surface Temperature With 13 Figures