Patterns in Catch Per Unit Effort of Native Prey Fish and Alien Piscivorous Fish in 7 Pacific Northwest USA Rivers

OBJECTIVE. Hospital readmissions are a current target of initiatives to reduce healthcare costs. This study quantified the association between having a clinical culture positive for 1 of 3 prevalent hospital-associated organisms and time to hospital readmission. DESIGN. Retrospective cohort study. PATIENTS AND SETTING. Adults admitted to an academic, tertiary care referral center from January 1, 2001, through December 31, 2008. METHODS. The primary exposure of interest was a clinical culture positive for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), or Clostridium difficile obtained more than 48 hours after hospital admission during the index hospital stay. The primary outcome of interest was time to readmission to the index facility. Multivariable Cox proportional hazards models were used to model the adjusted association between positive clinical culture result and time to readmission and to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS. Among 136,513 index admissions, the prevalence of hospital-associated positive clinical culture result for 1 of the 3 organisms of interest was 3%, and 35% of patients were readmitted to the index facility within 1 year after discharge. Patients with a positive clinical culture obtained more than 48 hours after hospital admission had an increased hazard of readmission (HR, 1.40; 95% CI, 1.33-1.46) after adjusting for age, sex, index admission length of stay, intensive care unit stay, Charlson comorbidity index, and year of hospital admission. CONCLUSIONS. Patients with healthcare-associated infections may be at increased risk of hospital readmission. These findings may be used to impact health outcomes after discharge from the hospital and to encourage better infection prevention efforts. Infect Control Hosp Epidemiol 2012; 33(6): 539-544Keywords: Stay, Therapy, Length, Surveillance, Mortality, Outcomes, Resistant staphylococcus-aureus, Impact, Model, Risk-factor

Abstract This study applied the Model of Acidification

of Groundwater in Catchments (MAGIC) to estimate the sensitivity of 66 watersheds in the Southern Blue Ridge Province of the Southern Appalachian Mountains, United States, to changes in atmospheric sulfur (S) deposition. MAGIC predicted that stream acid neutralizing capacity (ANC) values were above 20 μeq/L in all modeled watersheds in 1860. Hindcast simulations suggested that the media

Jewels across the Landscape: Monitoring and Assessing the Quality of Lakes and Reservoirs in the United States

An early naturalist described lakes as “jewels” across the landscape and indeed they were…at the end of the nineteenth century. As we settled the country and began to utilize the lake resource for our needs, things changed. Additionally, our needs for water brought about the construction of impoundments from ice ponds to small stock ponds up to mainstem impoundments along our major rivers. The lake resource in the United States now includes natural lakes in our northern tier of states, unique physiographic regions such as Florida and the Sand Hills of Nebraska, and the mountainous regions, and impoundments scattered across the entire landscape. In this chapter, we will describe efforts by an unique partnership between the individual states and tribal nations of the USA and the US Environmental Protection Agency to monitor and assess these systems. These efforts go beyond single water quality (chemistry) issues and include assessments targeting the goal of the Clean Water Act, namely, restoring, maintaining, and protecting the chemical, physical, and biological integrity of the nation’s lakes and reservoirs

Rivers and Streams: Upgrading Monitoring of the Nation’s Freshwater Resources - Meeting the Spirit of the Clean Water Act

The goal of the Clean Water Act (CWA) is to restore and maintain the chemical, physical and biological integrity of the waters in the United States. Much of the monitoring and assessment is reasonably delegated to the States to monitor and report the condition of their water to Congress through the Environmental Protection Agency. States have historically been fully occupied in monitoring the most egregious water quality problems along with select high priority water bodies. This approach, while addressing State priorities with finite resources, does not capture the full spectrum and scope of water quality conditions within and across State boundaries. Hence, the reporting on progress in meeting the goals of the CWA has not been realized. In this chapter, we describe the partnership between EPA, the States and Tribes to remedy this information gap for rivers and streams. Filling this gap requires both improved monitoring designs to reflect conditions across all waters as well as the expansion of indicators to move beyond water chemistry to include all three elements of the CWA goal—chemical, physical and biological integrity

Estimating vertebrate, benthic macroinvertebrate, and diatom taxa richness in raftable Pacific Northwest rivers for bioassessment purposes

The number of sites sampled must be considered when determining the effort necessary for adequately assessing taxa richness in an ecosystem for bioassessment purposes; however, there have been few studies concerning the number of sites necessary for bioassessment of large rivers. We evaluated the effect of sample size (i.e., number of sites) necessary to collect vertebrate (fish and aquatic amphibians), macroinvertebrate, and diatom taxa from seven large rivers in Oregon and Washington, USA during the summers of 2006–2008. We used Monte Carlo simulation to determine the number of sites needed to collect 90–95% of the taxa 75–95% of the time from 20 randomly located sites on each river. The river wetted widths varied from 27.8 to 126.0 m, mean substrate size varied from 1 to 10 cm, and mainstem distances sampled varied from 87 to 254 km. We sampled vertebrates at each site (i.e., 50 times the mean wetted channel width) by nearshore-raft electrofishing. We sampled benthic macroinvertebrates nearshore through the use of a 500-μm mesh kick net at 11 systematic stations. From each site composite sample, we identified a target of 500 macroinvertebrate individuals to the lowest possible taxon, usually genus. We sampled benthic diatoms nearshore at the same 11 stations from a 12-cm² area. At each station, we sucked diatoms from soft substrate into a 60-ml syringe or brushed them off a rock and rinsed them with river water into the same jar. We counted a minimum of 600 valves at 1,000× magnification for each site. We collected 120–211 diatom taxa, 98–128 macroinvertebrate taxa, and 14–33 vertebrate species per river. To collect 90-95% of the taxa 75-95% of the time that were collected at 20 sites, it was necessary to sample 11–16 randomly distributed sites for vertebrates, 13–17 sites for macroinvertebrates, and 16–18 sites for diatoms. We conclude that 12–16 randomly distributed sites are needed for cost-efficient sampling of vertebrate richness in the main stems of our study rivers, but 20 sites markedly underestimates the species richness of benthic macroinvertebrates and diatoms in those rivers.KEYWORDS: Fish, Benthos, Oregon, Washington, Large unwadeable rivers, Sampling effort, Periphyto

Non-wadeable river bioassessment: spatial variation of benthic diatom assemblages in Pacific Northwest rivers, USA

Current bioassessment efforts are focused on small wadeable streams, at least partly because assessing ecological conditions in non-wadeable large rivers poses many additional challenges. In this study, we sampled 20 sites in each of seven large rivers in the Pacific Northwest, USA, to characterize variation of benthic diatom assemblages among and within rivers relative to environmental conditions. Analysis of similarity (ANOSIM) indicated that diatom assemblages were significantly different among all the seven rivers draining different ecoregions. Longitudinal patterns in diatom assemblages showed river-specific features. Bray–Curtis dissimilarity index values did not increase as a function of spatial distance among the sampled reaches within any river but the Malheur. Standardized Mantel r of association between assemblage similarity and spatial distance among sites ranged from a high of 0.69 (Malheur) to a low of 0.18 (Chehalis). In the Malheur River, % monoraphids, nitrogen-tolerant taxa, and beta-mesosaprobous taxa all decreased longitudinally while % motile taxa, especially Nitzschia, showed an opposite trend, reflecting a strong in-stream water quality gradient. Similar longitudinal trends in water quality were observed in other rivers but benthic diatom assemblages showed either weak response patterns or no patterns. Our study indicated that benthic diatom assemblages can clearly reflect among-river factors. The relationships between benthic diatom assemblages and water quality within each river may depend on the strength of the water quality gradients, interactive effects of water quality and habitat conditions, and diatom sampling design.Keywords: River littoral zones, Pacific Northwest, Non-wadeable rivers, Benthic diatomsKeywords: River littoral zones, Pacific Northwest, Non-wadeable rivers, Benthic diatom

Algae–P relationships, thresholds, and frequency distributions guide nutrient criterion development

Abstract. We used complementary information collected using different conceptual approaches to develop recommendations for a stream nutrient criterion based on responses of algal assemblages to anthropogenic P enrichment. Benthic algal attributes, water chemistry, physical habitat, and human activities in watersheds were measured in streams of the Mid-Atlantic Highlands region as part of the Environmental Monitoring and Assessment Program of the US Environmental Protection Agency. Diatom species composition differed greatly between low-and high-pH reference streams; therefore, analyses for criterion development were limited to a subset of 149 well-buffered streams to control for natural variability among streams caused by pH. Regression models showed that TP concentrations were ;10 lg/L in streams with low levels of human activities in watersheds and that TP increased with % agriculture and urban land uses in watersheds. The 75 th percentile at reference sites was 12 lg TP/L. Chlorophyll a and ash-free dry mass increased and acid and alkaline phosphatase activities decreased with increasing TP concentration. The number of diatom taxa, evenness, proportion of expected native taxa, and number of high-P taxa increased with TP concentration in streams. In contrast, the number of low-P native taxa and % low-P individuals decreased with increasing TP. Lowess regression and regression tree analysis indicated nonlinear relationships for many diversity indices and attributes of taxonomic composition with respect to TP. Thresholds in these responses occurred between 10 and 20 lg/L and helped justify recommending a P criterion between 10 and 12 lg TP/L to protect highquality biological conditions in streams of the Mid-Atlantic Highlands

Influence of rare species on electrofishing distance when estimating species richness of stream and river reaches

Abstract.-The electrofishing distance needed to estimate fish species richness at the stream or river reach scale is an important question in fisheries science. This distance is governed by the shape of the species accumulation curve, which, in turn, is influenced by a combination of factors, including the number of species, their overall abundances, habitat associations, the efficiency of the sampling method, and the occurrence of rare species. In this study we document the influence of rare species on the species accumulation curves from stream and river sites in data sets from five dispersed regions of the USA. Spatial discontinuity (i.e., a noncontinuous distribution within reaches) was observed in four of the five data sets, and the four data sets contained numerically rare species represented by one or two individuals (termed singletons and doubletons, respectively). Numerically rare species were typically proportionately rare (i.e., ,1% of the total number of individuals captured), but proportionately rare species were not always numerically rare and were dependent on the total number of fish captured. Species richness asymptotes were reached at shorter electrofishing distances when singletons and doubletons were removed. The number of singletons and doubletons in the samples remained relatively constant with increasing sampling effort (i.e., sampling distance and total abundance). Simulation modeling indicated that individual aggregation within species was not a plausible reason for spatially discontinuous species distributions. When accurately detecting the presence of species is a sampling goal, the presence and prevalence of numerically rare species may need to be considered in determining sampling protocols

Continental-Scale Increase in Lake and Stream Phosphorus: Are Oligotrophic Systems Disappearing in the United States?

This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.We describe continental-scale increases in lake and stream total phosphorus (TP) concentrations, identified through periodic probability surveys of thousands of water bodies in the conterminous U.S. The increases, observed over the period 2000–2014 were most notable in sites in relatively undisturbed catchments and where TP was initially low (e.g., less than 10 μg L⁻¹). Nationally, the percentage of stream length in the U.S. with TP ≤ 10 μg L⁻¹ decreased from 24.5 to 10.4 to 1.6% from 2004 to 2009 to 2014; the percentage of lakes with TP ≤ 10 μg L⁻¹ decreased from 24.9 to 6.7% between 2007 and 2012. Increasing TP concentrations appear to be ubiquitous, but their presence in undeveloped catchments suggests that they cannot be entirely attributed to either point or common non-point sources of TP

Comment on Bachmann et al. (2013): A nonrepresentative sample cannot describe the extent of cultural eutrophication of natural lakes in the United States

In their recent paper, Bachmann et al. (2013) evaluate the extent to which natural lakes in the contiguous United States have been affected by cultural eutrophication since Europe-an settlement, using paleolimnological data collected during the 2007 National Lakes Assessment (NLA; U.S. Environ-mental Protection Agency [USEPA] 2009). The NLA sites were selected using a statistically valid sampling design that allows for the overall ecological condition of the nation’s lakes to be accurately characterized (USEPA 2009). Given the current consensus among limnologists regarding the prevalence of culturally eutrophic lakes (Finlayson and D’Cruz 2005; Carpenter et al. 2011), the conclusion of Bachmann et al. that ‘‘in the United States of America, the extent that natural lakes have been changed by cultural eutrophication does not seem to be large’’ (Bachmann et al. 2013, p. 950) is surprising. The findings of Bachmann et al. supporting this statement are not based on the entire NLA sample of natural lakes but rather on a subset of them. We demonstrate below that not only is this subset not representative of the entire population of natural lakes in the United States, but that it is biased toward lakes in regions with less anthropogenic activity and substantially lower nutrient concentrations. Consequently, we argue that the conclusions drawn by Bachmann et al. (2013) at the national scale are based upon a statistically flawed analysis