Channel Evolution Model of Semiarid Stream Response to Urban‐Induced Hydromodification1

Hawley, Robert J., Brian P. Bledsoe, Eric D. Stein, and Brian E. Haines, 2012. Channel Evolution Model of Semiarid Stream Response to Urban‐Induced Hydromodification. Journal of the American Water Resources Association (JAWRA) 48(4): 722‐744. DOI: 10.1111/j.1752‐1688.2012.00645.x Abstract: We present a novel channel evolution model (CEM) that qualitatively describes morphologic responses of semiarid channels to altered hydrologic and sediment regimes associated with urbanization (hydromodification). The CEM is based on southern California data from 83 detailed channel surveys, hundreds of synoptic surveys, and historical analyses of aerial photographs along 14 reaches. Channel evolution sometimes follows the well‐known sequence described by Schumm et al. (Incised Channels: Morphology, Dynamics, and Control, Water Resources Publications, Littleton, Colorado, 1984) for incising, single‐thread channels; however, departures from this sequence are common and include transitions of single thread to braided evolutionary endpoints, as opposed to a return to quasi‐equilibrium single‐thread planform. Thresholds and risk factors associated with observed channel response are also presented. In particular, distance to grade control and network position emerged as key controls on channel response trajectory. The CEM and quantitative extensions provide managers with a framework for understanding channel responses and rehabilitation alternatives, and may be transferable to other semiarid settings. It also offers insights regarding channel susceptibility to hydromodification, highlights key boundary conditions for high‐risk channels, and underscores critical knowledge gaps in predicting the complex, discontinuous response trajectories that are highly prevalent in urbanized watersheds.     

Mechanism(s) of long chain n-3 essential fatty acid production in two species of heterotrophic protists: <Emphasis Type="Italic">Oxyrrhis marina</Emphasis> and <Emphasis Type="Italic">Gyrodinium dominans</Emphasis>

As intermediaries, some heterotrophic protists can enhance the content of the long chain n-3 essential fatty acids (LCn-3EFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), of low food quality algae for subsequent use at higher trophic levels. However, the mechanisms that produce LCn-3EFAs are presently unknown, although LCn-3EFA production by heterotrophic protists at the phytoplankton–zooplankton interface may potentially affect the nutritional status of the pelagic system. We investigated whether the heterotrophic protists, Oxyrrhis marina and Gyrodinium dominans, produce LCn-3EFAs via elongation and desaturation of dietary LCn-3EFA precursors and/or synthesize LCn-3EFAs de novo by: (1) feeding the two heterotrophic protists with a prey deficient in n-3 fatty acids, (2) incubating them in medium containing ¹³C-labeled sodium acetate, and (3) feeding the two protists gelatin acacia microspheres (GAMs) containing a deuterium-labeled LCn-3EFA precursor, linolenic acid [18:3(n-3)-d4]. Both O. marina and G. dominans synthesized EPA and DHA when fed the n-3 fatty acid-deficient prey, Perkinsus marinus, a parasitic protozoan. O. marina, but not G. dominans utilized ¹³C-labeled acetate from the medium to produce uniformly labeled fatty acids, including DHA. Both heterotroph species consumed GAMs containing 18:3(n-3)-d4 and catabolized 18:3(n-3)-d4 to 16:3(n-3)-d4 and 14:3(n-3)-d4, while no 20 or 22 carbon metabolites of 18:3(n-3)-d4 were detected. These results suggest that O. marina and G. dominans do not elongate and desaturate dietary LCn-3EFA precursors to produce LCn-3EFAs, but rather they produce LCn-3EFAs de novo, possibly via a polyketide synthesis pathway.     

Biosensing paraoxon in simulated environmental samples by immobilized organophosphorus hydrolase in functionalized mesoporous silica

There is a critical need for highly sensitive, cost-effective sensors to conduct ecological analyses for environmental and homeland security-related applications. Enzyme biosensors, which are currently gaining acceptance for environmental monitoring applications, need improvements to deliver faster measurements with stabilized sensing elements, e.g., enzymes. We report here on a method which significantly overcomes this difficulty, and demonstrate its application in a biosensor for aquatic environmental applications. A fast-responding and stable biosensor was developed via immobilization of organophosphorus hydrolase (OPH) in functionalized mesoporous silica (FMS) with pore sizes in tens of nanometers. The OPH-FMS composite was held on glassy carbon electrode by a dried Nafion gel and FMS protected OPH from Nafion-resulted activity loss. The resulting enzyme biosensor, when integrated with an electrochemical instrument, responded rapidly to low paraoxon concentration and achieved steady-state current in less than 10 s, with a detection limit of 4.0x10(-7) M paraoxon. The biosensor was tested for detection of paraoxon in simulated environmental samples, under wide-ranging physicochemical conditions. Results clearly indicate high recovery efficiencies in aqueous solutions (96 to 101%) at different pH, total organic carbon, total dissolved solids, and total suspended solids, and demonstrate the ability of the biosensor unit to continuously monitor paraoxon in aqueous conditions similar to those found in river and lake systems.     

The Four Cs of disaster partnering: communication,cooperation, coordination and collaboration

Public, nonprofit and private organisations respond to large‐scale disasters domestically and overseas. Critics of these assistance efforts, as well as those involved, often cite poor interorganisational partnering as an obstacle to successful disaster response. Observers frequently call for ‘more’ and ‘better’ partnering. We found important qualitative distinctions existed within partnering behaviours. We identified four different types of interorganisational partnering activities often referred to interchangeably: communication, cooperation, coordination and collaboration—the Four Cs. We derived definitions of the Four Cs from the partnering literature. We then tested them in a case study of the response to the 2010 Haiti earthquake. We suggest that the Four Cs are distinct activities, that organisations are typically strong or weak in one or more for various reasons, and that the four terms represent a continuum of increased interorganisational embeddedness in partnering activities.     

Consumer-resource body-size relationships in natural food webs

It has been suggested that differences in body size between consumer and resource species may have important implications for interaction strengths, population dynamics, and eventually food web structure, function, and evolution. Still, the general distribution of consumer-'resource body-size ratios in real ecosystems, and whether they vary systematically among habitats or broad taxonomic groups, is poorly understood. Using a unique global database on consumer and resource body sizes, we show that the mean body-size ratios of aquatic herbivorous and detritivorous consumers are several orders of magnitude larger than those of carnivorous predators. Carnivorous predator-prey body-size ratios vary across different habitats and predator and prey types (invertebrates, ectotherm, and endotherm vertebrates). Predator-prey body-size ratios are on average significantly higher (1) in freshwater habitats than in marine or terrestrial habitats, (2) for vertebrate than for invertebrate predators, and (3) for invertebrate than for ectotherm vertebrate prey. If recent studies that relate body-size ratios to interaction strengths are general, our results suggest that mean consumer-resource interaction strengths may vary systematically across different habitat categories and consumer types.     

Agricultural Production Monitoring in the Sahel Using Remote Sensing: Present Possibilities and Research Needs

The main objective is to review the current status of research related to the monitoring of agricultural production in the Sahel (west Africa). The Sahel suffers from frequent shortages of food. It is therefore important to have a tool to monitor environmental variables, and thus crop production, during the agricultural season. Satellite remote sensing can contribute significantly to such a system by collecting information on crops and on environmental variables at a sub-continental geographical scale and with a high temporal frequency. One part of the problem is to estimate crop acreage. The technique of area-sampling frame has to adapted to the Sahelian landscape, which is dominated by traditional farming systems. The second part is to estimate crop yields. Three main approaches exist: statistical, semi-deterministic or deterministic. The use of vegetation indices is discussed as well as techniques to derive biophysical variables from remotely-sensed data. Finally, the integration of these remote-sensing techniques with crop-growth models is discussed and some research needs are identified. It is argued that the quantitative assessment of agricultural production in the Sahel should be based on the integration of remotely-sensed data with semi-deterministic agrometeorological models. This approach will allow a regionalization of the production estimates.     

Wyoming's industrial siting permit process and environmental impact assessment

The problem of management of industrial residuals can be reduced through a rational system for siting and planning major industrial facilities. In the United States, Wyoming has moved in the direction of establishing a one-stop permitting system that provides important information for air and water quality planning and solid waste management with a minimum of regulatory overlap. This paper describes Wyoming's Industrial Development Information and Siting Act of 1975 and suggests ways in which the Wyoming permitting system can be improved and applied elsewhere.     

The Historical Development of Public Health Responses to Disasters

The first of a series of state-of-the-art reviews commissioned to mark Disasters' 21st anniversary, this paper considers key publications on public health aspects of natural disasters, refugee emergencies and complex humanitarian disasters over the past twenty-odd years. The literature is reviewed and important signposts highlighted showing how the field has developed. This expanding body of epidemiological research has provided a basis for increasingly effective prevention and intervention strategies.