Abundance and stomach content analysis of threadfin shad in Lake Mead, Nevada: Do invasive quagga mussels affect this prey species?

Lake Mead, Nevada is the largest reservoir by volume in the United States, as well as a popular sport fishing destination. In January 2007, the invasive quagga mussel Dreissena rostriformis bugensis (Andrusov, 1897) was discovered in the reservoir and concerns began to arise about potential alterations to the aquatic environment. The Lake Mead sport fishery is reliant on the sustainability of prey species like the threadfin shad [Dorosoma petenense (Günther, 1867)]. This study examined 20-year trends in historic abundance of the threadfin shad, before, and shortly after, the discovery of quagga mussels in the system. Larval shad trawl data collected in Las Vegas Bay and Overton Arm portions of Lake Mead were analyzed in the present study. Two-way analysis of variances showed that the abundance of this prey fish has not changed following quagga mussel invasion (P \u3e 0.05). Post-quagga mussel discovery collections of adult threadfin shad from Las Vegas Bay ranged from 113 to 212 mm total length (TL) (mean = 184 mm; n = 170). Shad from Overton Arm ranged from 131 to 197 mm TL (mean = 150 mm; n = 27). Stomach contents were analyzed. The proportion of cladocerans in stomach contents differed significantly from spring to winter in Las Vegas Bay (P = 0.008); whereas the proportion of copepods did not show statistically relevant differences regarding seasonality (P = 0.562). Initial trends in lower trophic level dynamics in response to quagga mussel invasion has yet to reveal significant effects in Las Vegas Bay or Overton Arm. Long-term monitoring on threadfin shad is needed to evaluate potential impacts from invasive quagga mussels in Lake Mead

Ecological Consequences of Invasion of the Quagga Mussel (Dreissena bugensis Andrusov 1897) into Lake Mead

Consequences of Invasion of the Quagga Mussel into Lake Mea

Longitudinal Assessment of Growth in Hypoplastic Left Heart Syndrome: Results From the Single Ventricle Reconstruction Trial

Background: We sought to characterize growth between birth and age 3 years in infants with hypoplastic left heart syndrome who underwent the Norwood procedure. Methods and Results: We performed a secondary analysis using the Single Ventricle Reconstruction Trial database after excluding patients 2 SD below normal). Failure to find consistent risk factors supports the strategy of tailoring nutritional therapies to patient‐ and stage‐specific targets. Clinical Trial Registration URL: http://clinicaltrials.gov/. Unique identifier: NCT00115934

Physician assessments of drug seeking behavior: A mixed methods study.

Pain complaints are common, but clinicians are increasingly concerned about overuse of opioid pain medications. This may lead patients with actual pain to be stigmatized as "drug-seeking," or attempting to obtain medications they do not require medically. We assessed whether patient requests for specific opioid pain medication would lead physicians to classify them as drug-seeking and change management decisions.Mixed-methods analysis of interviews with 192 office-based primary care physicians after viewing video vignettes depicting patients presenting with back pain. For each presentation physicians were randomly assigned to see either an active request for a specific medication or a more general request for help with pain. The main outcome was assignment by the physician of "drug-seeking" as a potential diagnosis among patients presenting with back pain. Additional outcomes included other actions the physician would take and whether the physician would prescribe the medication requested. A potential diagnosis of drug-seeking behavior was included by 21% of physicians seeing a specific request for oxycodone vs. 3% for a general request for help with back pain(p<0.001). In multivariable models an active request was most strongly associated with a physician-assigned diagnosis of drug-seeking behavior(OR 8.10; 95% CI 2.11-31.15;p = 0.002); other major patient and physician characteristics, including gender and race, did not have strong associations with drug-seeking diagnosis. Physicians described short courses of opioid medications as a strategy for managing patients with pain while avoiding opioid overuse.When patients make a specific request for opioid pain medication, physicians are far more likely to suspect that they are drug-seeking. Physician suspicion of drug-seeking behavior did not vary by patient characteristics, including gender and race. The strategies used to assess patients further varied widely. These findings indicate a need for the development of better clinical tools to support the evaluation and management of patients presenting with pain

Potential ecological consequences of invasion of the quagga mussel (Dreissena bugensis) into Lake Mead, Nevada–Arizona

The recent invasion of the quagga mussel (Dreissena bugensis) in Lake Mead, Nevada–Arizona, USA has the potential to alter biological relationships in this western reservoir. We evaluated the potential impacts by examining several measurements in the Boulder Basin of Lake Mead after the introduction of quagga mussel (2007–2008). Analysis of variance did not reveal any basin-wide changes in chlorophyll a concentrations or water clarity (Secchi disk depth). Although significantly lower chlorophyll a concentrations were found in the outer basin, this reduction was likely related to the decline of dissolved phosphorus concentrations. The abundance of cladocerans, copepods or rotifers has not changed since 2007. Overall, the results suggest that there are no statistically significant changes to many of the standard water quality indices routinely measured in the Boulder Basin of Lake Mead; however, given the complexity of biological, chemical and physical processes driving this ecosystem, the long-term impacts of quagga mussels remain uncertain. This manuscript identifies impacts known to be altered by quagga and zebra mussels in other systems and aims to help lake managers develop experimental and monitoring programs that will accurately address the impacts of quagga mussels