Water quality and planktonic microbial assemblages of isolated wetlands in an agricultural landscape

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Wetlands 31 (2011): 885-894, doi:10.1007/s13157-011-0203-6.Wetlands provide ecosystem services including flood protection, water quality enhancement, food chain support, carbon sequestration, and support regional biodiversity. Wetlands occur in human-altered landscapes, and the ongoing ability of these wetlands to provide ecosystem services is lacking. Additionally, the apparent lack of connection of some wetlands, termed geographically isolated, to permanent waters has resulted in little regulatory recognition. We examined the influence of intensive agriculture on water quality and planktonic microbial assemblages of intermittently inundated wetlands. We sampled 10 reference and 10 agriculturally altered wetlands in the Gulf Coastal Plain of Georgia. Water quality measures included pH, alkalinity, dissolved organic carbon, nutrients (nitrate, ammonium, and phosphate), and filterable solids (dry mass and ash-free dry mass). We measured abundance and relative size distribution of the planktonic microbial assemblage (< 45 μm) using flow cytometry. Water quality in agricultural wetlands was characterized by elevated nutrients, pH, and suspended solids. Autotrophic microbial cells were largely absent from both wetland types. Heterotrophic microbial abundance was influenced by nutrients and suspended matter concentration. Agriculture caused changes in microbial assemblages forming the base of wetland food webs. Yet, these wetlands potentially support important ecological services in a highly altered landscape.Funding was provided by the Joseph W. Jones Ecological Research Center.2012-07-2

Elevated aluminium concentration in acidified headwater streams lowers aquatic hyphomycete diversity and impairs leaf-litter breakdown.

Aquatic hyphomycetes play an essential role in the decomposition of allochthonous organic matter which is a fundamental process driving the functioning of forested headwater streams. We studied the effect of anthropogenic acidification on aquatic hyphomycetes associated with decaying leaves of Fagus sylvatica in six forested headwater streams (pH range, 4.3-7.1). Non-metric multidimensional scaling revealed marked differences in aquatic hyphomycete assemblages between acidified and reference streams. We found strong relationships between aquatic hyphomycete richness and mean Al concentration (r = -0.998, p < 0.0001) and mean pH (r = 0.962, p < 0.002), meaning that fungal diversity was severely depleted in acidified streams. By contrast, mean fungal biomass was not related to acidity. Leaf breakdown rate was drastically reduced under acidic conditions raising the issue of whether the functioning of headwater ecosystems could be impaired by a loss of aquatic hyphomycete species

Biliary dyskinesia: a potentially unrecognized cause of abdominal pain in children

Biliary dyskinesia is defined as symptomatic biliary colic without cholelithiasis, and is diagnosed during cholescintigraphy by assessing gallbladder emptying with cholecystokinin (CCK) stimulation. Unfortunately, gallbladder emptying is not routinely assessed during cholescintigraphy in pediatric patients. The purpose of this review is to assess the effectiveness of cholecystectomy in patients with chronic abdominal pain and delayed gallbladder emptying and to assess whether these findings correlate with the histologic evidence of chronic cholecystitis. We retrospectively reviewed the medical records of all patients ( n =16) at our institution from October 1997 to August 2001 who underwent quantitative cholescintigraphy with CCK stimulation that demonstrated delayed gallbladder emptying (<35% at 60 min) and who subsequently underwent cholecystectomy. Laparoscopic cholecystectomy was performed in 16 patients with chronic abdominal pain. All 16 patients had delayed gallbladder emptying (mean ejection fraction : 15±8%, range: 3–32%). The mean age was 12±2 years (range: 8–17 years). Presenting symptoms included abdominal pain (86%), fatty food intolerance (27%), emesis (13%), and diarrhea (13%). Mean duration of abdominal pain before operation was 11±19 months (range: 2 weeks–6 years). One patient’s symptoms persisted postoperatively , but abdominal pain resolved in all other patient s. Histologic evidence of chronic cholecystitis was demonstrated in 86% of surgical specimens. Five patients underwent concurrent appendectomy , and all had normal appendiceal histology. Our experience suggests that children with chronic abdominal pain and delayed gallbladder emptying on CCK-stimulated cholescintigraphy are likely to benefit from cholecystectomy and to have histologic evidence of chronic cholecystitis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47166/1/383_2004_Article_1234.pd

The economics of parasitic diseases: Research priorities

Parasitic diseases are primarily diseases of poverty. At serious risk are individuals, communities and countries least able to afford the costs of treatment of prevention. In turn, economic development projects which aim to increase income levels may lead to negative results because of increased transmission of parasitic diseases often results. In attempting to analyse the economic consequences of parasitic diseases and the economics of their control, economists have usually relied on the tools of cost-benefit analysis, cost-effectiveness analysis and financial analysis. These efforts are briefly reviewed in the paper. The results have been subject to considerable criticism because of conceptual and methodological problems. For example, most studies have not taken into account the epidemiology and natural history of the disease in estimating the associated economic losses, thereby leading to inappropriate conclusions. The UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases through its Social and Economic Research Scientific Working Group (SER-SWG) is promoting research on the economics of parasitic diseases. In an attempt to improve the usefulness and reliability of such studies, conceptual and methodological approaches have been suggested which are reported on here. To improve the research design of these projects, a conceptual framework is proposed which consists of four components: (1) baseline social, cultural and economic conditions influencing disease transmission; (2) resources already invested in the health system and investments in other related sectors such as agriculture, housing, water supply and sanitation; (3) health consequences resulting from (1) and (2); and (4) social and economic consequences resulting from (3). A key concern in relation to the framework is to determine the most useful basis for linking results from studies of one component to another so as to analyse more systematically the impacts of disease on individuals and society. Such studies are inherently interdisciplinary and close collaboration of economists with medical scientists and disease control programme staff is needed to ensure completeness and reliability of input data and results. Results from these studies could be used to inform national decision-makers about the social and economic consequences of the parasitic diseases and their control and, thus, should strengthen support for increased investment to reduce the parasitic disease burden in developing countries.

Allied Health Manpower Strategies: Estimates of the Potential Gains from Efficient Task Delegation

This study analyzes the potential impact of physician extenders on the productivity of primary care practices and considers the consequent implica tion for future health manpower requirements. A number of previous inves tigations have evaluated a variety of extenders in experimental settings. This study, in contrast, constructs and operates a simulation model of the repre sentative practice permitting one to synthesize the experiences and insights of earlier demonstration projects. The model requires the practice to delegate tasks to paramedical personnel including the physician extender in such a way as to minimize the total cost of delivering a list of required medical services. The alternative acceptable techniques for delivering care are defined by the number of minutes of each type of medical personnel that must be employed in producing each service. Primary care is characterized by distinct medical services. The model reveals that physician extenders could increase the productivity of a representative primary care practice by up to 74 per cent Alternatively, the commitment of physician time required to serve a patient load of 100 visits a week might be reduced by 14.2 hours through effective use of an extender. The article concludes with observations on the implications of physician extenders for future health manpower requirements. O rig in a l A rticles The demand for medical services is in creasing dramatically. As public and private insurance schemes develop to cover the costs of care, the demands on the health care system will expand further. These ex panded demands have prompted experts to propose that additional resources b e allo cated towards existing programs of physi cian training. Such proposals are premised on the the assumption that th e current organization of the health care system will continue indefinitely. However, in view of the extraordinary cost of medical education and the great length of time required to develop new training programs, it seems appropriate to explore alternative strate gies for the expansion of medical services. Considerable i n t e r e s t h a s developed within the medical profession in task dele gation and in the training of new classes of 45

Is Species Richness Congruent Among Taxa? Surrogacy, Complementarity, And Environmental Correlates Among Three Disparate Taxa In Geographically Isolated Wetlands

Globally, there is a growing awareness that geographically isolated wetlands contribute to important landscape functions and ecological services. One of their most important functions is providing habitat to a diverse fauna and flora adapted to variable wet and dry environments. We focus on analysis of similarities among three distinct taxa, vascular plants, aquatic beetles, and amphibians, in isolated wetlands in the southeastern coastal plain of Georgia. Although species richness for these three taxa is quite high in isolated wetlands at a regional scale, we found a low degree of congruence in species richness and species composition among taxa. This finding demonstrates that none of these groups could be used as a surrogate for the overall biodiversity of these wetlands represented by the three taxa. We identified environmental factors influencing the complex patterns of species richness and distribution for the three groups that indicate biotic and abiotic processes operate at different scales for each taxonomic group and for individual species. Our study illustrates the importance of considering structural diversity, hydrologic variation, and landscape position as key elements to understanding overall diversity represented by the three taxa in isolated wetlands and in developing assessment tools of wetland condition. © 2011 Elsevier Ltd. All rights reserved

Using hydrogeomorphic patterns to predict groundwater discharge in a karst basin: Lower Flint River Basin, southwestern Georgia, USA

Study region: The Lower Flint River Basin (LFRB): a karst catchment in southwestern Georgia, USA. Study focus: Using the U.S. EPA Reach File 3 data set, we generated stream reach azimuths for all tributaries of the Lower Flint River Basin (LFRB) in southwestern Georgia, USA, then compared these results to regional bedrock jointing orientations and stream chemistry (indicating incoming groundwater discharge) in one tributary of the LFRB, Ichawaynochaway Creek. Our objective was to determine if stream bearing might be a useful predictor of increased groundwater discharge in streams of the LFRB where groundwater development has significantly impacted baseflows. New hydrological insights for the region: We identified a dominant N-S trend in 44% of reaches in tributaries of the LFRB with lesser E-W, NNW, NW and NE trends. Bedrock joints and stream reaches in Ichawaynochaway Creek (a tributary of the Flint River) shared similar azimuth trends. When we compared stream reach orientation with known locations of enhanced groundwater inputs (previously detected by Rugel and others) we found that 55% of the time reaches in Ichawaynochaway Creek with increased groundwater discharge followed NW or NNW bearings (mean N49W). Further investigation to replicate these results in other tributaries of the LFRB is warranted and may help inform management strategies which could protect both ecological and economic interests in this region. Keywords: Grondwater discharge, Karst, Water resources, Groundwater-surface water interactio