Rise of Ruppia in Chesapeake Bay: Climate change-driven turnover of foundation species creates new threats and management opportunities.

Global change has converted many structurally complex and ecologically and economically valuable coastlines to bare substrate. In the structural habitats that remain, climate-tolerant and opportunistic species are increasing in response to environmental extremes and variability. The shifting of dominant foundation species identity with climate change poses a unique conservation challenge because species vary in their responses to environmental stressors and to management. Here, we combine 35 y of watershed modeling and biogeochemical water quality data with species comprehensive aerial surveys to describe causes and consequences of turnover in seagrass foundation species across 26,000 ha of habitat in the Chesapeake Bay. Repeated marine heatwaves have caused 54% retraction of the formerly dominant eelgrass (Zostera marina) since 1991, allowing 171% expansion of the temperature-tolerant widgeongrass (Ruppia maritima) that has likewise benefited from large-scale nutrient reductions. However, this phase shift in dominant seagrass identity now presents two significant shifts for management: Widgeongrass meadows are not only responsible for rapid, extensive recoveries but also for the largest crashes over the last four decades; and, while adapted to high temperatures, are much more susceptible than eelgrass to nutrient pulses driven by springtime runoff. Thus, by selecting for rapid post-disturbance recolonization but low resistance to punctuated freshwater flow disturbance, climate change could threaten the Chesapeake Bay seagrass' ability to provide consistent fishery habitat and sustain functioning over time. We demonstrate that understanding the dynamics of the next generation of foundation species is a critical management priority, because shifts from relatively stable habitat to high interannual variability can have far-reaching consequences across marine and terrestrial ecosystems.

A Pleistocene legacy structures variation in modern seagrass ecosystems.

Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.

The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans.

While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.

Data synthesis for environmental management: A case study of Chesapeake Bay.

Synthesizing large, complex data sets to inform resource managers towards effective environmental stewardship is a universal challenge. In Chesapeake Bay, a well-studied and intensively monitored estuary in North America, the challenge of synthesizing data on water quality and land use as factors related to a key habitat, submerged aquatic vegetation, was tackled by a team of scientists and resource managers operating at multiple levels of governance (state, federal). The synthesis effort took place over a two-year period (2016-2018), and the results were communicated widely to a) scientists via peer review publications and conference presentations; b) resource managers via web materials and workshop presentations; and c) the public through newspaper articles, radio interviews, and podcasts. The synthesis effort was initiated by resource managers at the United States Environmental Protection Agencys' Chesapeake Bay Program and 16 scientist participants were recruited from a diversity of organizations. Multiple short, immersive workshops were conducted regularly to conceptualize the problem, followed by data analysis and interpretation that supported the preparation of the synthetic products that were communicated widely. Reflections on the process indicate that there are a variety of structural and functional requirements, as well as enabling conditions, that need to be considered to achieve successful outcomes from synthesis efforts.

Clinical Characterization of Pediatric Gastroparesis Using a Four-hour Gastric Emptying Scintigraphy Standard.

OBJECTIVES: Four-hour gastric emptying scintigraphy (GES) is the recommended method to identify both adult and childhood gastroparesis (GP). Previous pediatric studies have, however, not used this standard. We sought to determine the characteristics and outcomes of children versus adolescents with GP using the 4-hour GES evaluation. METHODS: We performed a retrospective chart review of pediatric patients diagnosed with GP by 4-hour GES (>10% retention at 4 hours). Demographics, body mass index, GP-related symptoms, comorbidities, etiologies, therapies (eg, medications), healthcare utilization, and response to therapy were captured systematically. Symptoms were compared from the initial versus last gastroenterology visit. Outcomes were categorized as no improvement; improvement (resolution of at least 1 symptom while remaining on therapy); and complete resolution of symptoms. RESULTS: A total of 239 subjects (12.1 ±â€Š4.1 years [mean ±â€Šstandard deviation], 70% girls) were included. The identified characteristics of childhood GP were broad with idiopathic GP being the most common etiology. Outcomes over a median of 22 months (25%-75%: 9.0-45.5 months) were 34.8% no improvement, 34.8% some improvement, and 30.3% with complete symptom resolution. Compared to younger children, adolescents had a higher female predominance (P < 0.01) and were more likely to have nausea (P = 0.006). Girls were more likely to have abdominal pain (P = 0.001), nausea (P = 0.03), and a documented diagnosis of dysautonomia (P = 0.03). Boys were more likely to have regurgitation (P = 0.006), gastroesophageal reflux disease (P = 0.02), and rumination (P = 0.02). CONCLUSIONS: Using the 4-hour GES standard, childhood GP has broad clinical characteristics and outcomes. There are several significant age- and sex-based differences in childhood GP.

Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region.

Humans strongly impact the dynamics of coastal systems, yet surprisingly few studies mechanistically link management of anthropogenic stressors and successful restoration of nearshore habitats over large spatial and temporal scales. Such examples are sorely needed to ensure the success of ecosystem restoration efforts worldwide. Here, we unite 30 consecutive years of watershed modeling, biogeochemical data, and comprehensive aerial surveys of Chesapeake Bay, United States to quantify the cascading effects of anthropogenic impacts on submersed aquatic vegetation (SAV), an ecologically and economically valuable habitat. We employ structural equation models to link land use change to higher nutrient loads, which in turn reduce SAV cover through multiple, independent pathways. We also show through our models that high biodiversity of SAV consistently promotes cover, an unexpected finding that corroborates emerging evidence from other terrestrial and marine systems. Due to sustained management actions that have reduced nitrogen concentrations in Chesapeake Bay by 23% since 1984, SAV has regained 17,000 ha to achieve its highest cover in almost half a century. Our study empirically demonstrates that nutrient reductions and biodiversity conservation are effective strategies to aid the successful recovery of degraded systems at regional scales, a finding which is highly relevant to the utility of environmental management programs worldwide.

Utility of Computed Tomography Overreading and Abdominal Ultrasound in Children With Suspected Appendicitis and Nondiagnostic Computed Tomography at Community Hospitals.

OBJECTIVE: The aim of the study was to examine the ability of overreading of computed tomography (CT) and right lower quadrant ultrasound (RLQ US) to diagnose appendicitis for children with suspected appendicitis with equivocal CTs at community hospitals. METHODS: This was a retrospective chart review of all children transferred to a children's hospital from community emergency departments with suspected appendicitis over 2 years for whom both CT and RLQ US were performed. RESULTS: One hundred eighty-four children were included with a median age of 10.8 years, and 57.6% were female. Community hospitals documented that CTs were equivocal for appendicitis in 110 (59.8%), positive in 63 (34.2%), and negative in 11 (6.0%). Ninety-seven CTs (88.1%) designated equivocal at community hospitals were later deemed interpretable by pediatric radiologists: 21 (19.1%) as appendicitis and 76 (69.1%) as normal. In 13 children (11.8%), both the community and children's hospital CT interpretations were equivocal. In equivocal cases, RLQ US was consistent with appendicitis in 6 (46.2%), normal in 5 (41.7%), and nondiagnostic in 2. κ value between CT interpretations at community versus children's hospital was 0.13 (95% confidence interval, 0.05-0.22), and κ value between CT interpretation at the children's hospital and RLQ US was 0.59 (95% confidence interval, 0.48-0.70). CONCLUSIONS: Most CTs deemed equivocal for appendicitis at community hospitals were interpretable by pediatric radiologists. In a few children for whom CTs were designated nondiagnostic, RLQ US provided a definitive diagnosis in almost 90% of cases. The first step in evaluation of children with suspected appendicitis for whom outside CTs are deemed equivocal should be to have the study reinterpreted by a pediatric radiologist.

Physiologic Ovarian Cysts versus Other Ovarian and Adnexal Pathologic Changes in the Preadolescent and Adolescent Population: US and Surgical Follow-up.

Background Ovarian and adnexal cysts are frequently encountered at US examinations performed in preadolescent and adolescent patients, yet there are few published studies regarding the outcomes of cysts in this population. Purpose To identify characteristics at US that help to distinguish physiologic ovarian cysts from nonphysiologic entities. Materials and Methods Female patients who underwent pelvic US with or without Doppler from January 2009 through December 2013 were identified by using a centralized imaging database. Patients older than 7 years and younger than 18 years with ovarian or adnexal cysts at least 2.5 cm were included. Demographic characteristics, date of surgery, surgical notes, and pathologic reports were extracted from the electronic medical record. Initial and follow-up dates of US, cyst size and complexity, imaging diagnosis, and change on subsequent US images were recorded. Statistical analysis was performed with the Wilcoxon rank sum and Kruskal-Wallis tests for continuous variables and the Fisher exact test for categorical variables. Results Of 754 patients who met inclusion criteria (age, 8-18 years; mean age, 14.6 years ± 1.9 [standard deviation]; mean cyst size, 5 cm ± 3.3), 409 patients underwent complete follow-up that included resolution at imaging (n = 250) or surgery (n = 159). In the patients with complete imaging follow-up, mean time to US documentation of resolution was 194 days ± 321; 59.6% (149 of 250) patients had nonsimple cyst characteristics. One-hundred fifty-nine patients underwent surgical intervention (mean cyst size, 8.5 cm ± 5.3), and 69.8% (111 of 159) of the cysts had simple characteristics. Of the 159 cysts, 100 (62.8%) were defined in the pathologic report as paratubal cysts. Of 409 patients, no malignancies were encountered in this study population with surgical or imaging resolution. Conclusion No malignancies were encountered in the study population and the majority of cysts resolved at follow-up imaging. Large size, persistence, and separability from the ovary were most helpful for identification of nonphysiologic paratubal cysts. © RSNA, 2019.

Pediatric percutaneous renal biopsies: comparison of complications between real-time ultrasound guidance and pre-procedure ultrasound-aided skin-marking techniques.

BACKGROUND: Percutaneous renal biopsy is a commonly performed procedure that guides decision-making for children with renal disease. OBJECTIVE: To compare complications from renal biopsies using real-time ultrasound (US) guidance versus pre-procedure US-aided skin-marking in children. MATERIALS AND METHODS: We conducted a priori power analysis using a risk-adjusted model, which indicated we needed a sample size of 643-714 procedures (effect size: 0.8). Then we retrospectively identified consecutive patients who underwent a percutaneous renal biopsy from Jan. 1, 2012, to Dec. 31, 2016. We categorized complications according to the Society of Interventional Radiology (SIR) criteria and compared rates using the Fisher exact test. We analyzed complication predictors using multivariate regression. RESULTS: The study consisted of 701 percutaneous renal biopsies in 553 patients: 313 used real-time US guidance and 388 used pre-procedure US-aided skin-marking. Among the 254/701 (36%) complications, 56/313 (18%) resulted from real-time US guidance and 198/388 (51%) from pre-procedure US-aided skin-marking (P<0.001). In the US real-time guidance group, 39/56 (70%) complications were SIR A, 8/56 (14%) SIR B, 6/56 (11%) SIR C and 3/56 (5%) SIR D. Among the pre-procedure US-aided skin-marking group, 139/198 (70%) complications were SIR A, 47/198 (24%) SIR B, 11/198 (6%) SIR C and 1/198 (1%) SIR D. Complications between the two groups were significantly different regarding SIR A (P<0.001) and SIR B complications (P<0.001) but not major complications. Multivariate regression demonstrated that complications were higher using US-aided pre-procedure skin-marking (odds ratio [OR]=6.30; 95% confidence interval [CI]=3.86, 10.27) than with US real-time guidance. CONCLUSION: Children and young adults who underwent real-time US-guided percutaneous renal biopsies had significantly fewer minor complications, including those requiring follow-up medical care, compared to those who underwent percutaneous renal biopsies with pre-procedure US-aided skin-marking. No difference was detected in the incidence of major complications.

Pediatric ileocolic intussusception: new observations and unexpected implications.

BACKGROUND: Ileocolic intussusception occurs when the terminal ileum "telescopes" into the colon. We observed that ileocolic intussusception lengths are similar regardless of location in the colon. OBJECTIVE: To examine the uniformity of ileocolic intussusception length and its relationship to colon location, symptom duration and reducibility. MATERIALS AND METHODS: We retrospectively reviewed ultrasound-diagnosed pediatric ileocolic intussusceptions initially treated with pneumatic reduction at the Mayo Clinic or Texas Children's Hospital. We recorded demographic, imaging and surgical findings including age, gender, symptom duration, location of the ileocolic intussusception, reducibility with air enema and, if fluoroscopically irreducible, surgical findings. RESULTS: We identified 119 ileocolic intussusceptions (64% boys), with 81% in the right colon. There was no significant relationship between ileocolic intussusception length and colon location (P=0.15), nor ileocolic intussusception length and symptom duration (P=0.36). Ileocolic intussusceptions were more distal with increasing symptom duration (P=0.016). Successful reductions were unrelated to symptom duration (P=0.84) but were more likely with proximal versus distal locations (P=0.02). CONCLUSION: Ileocolic intussusception lengths are relatively uniform regardless of location along the course of the colon where they present. Our findings suggest that most of the apparent distal propagation of ileocolic intussusceptions is not caused by increasing telescoping of small bowel across the ileocecal valve but rather by foreshortening of the right colon. This implies poor cecal fixation and confirms fluoroscopic and surgical observations of cecal displacement from the right lower quadrant with ileocolic intussusceptions. The movement of the leading edge of the ileocolic intussusception during reduction is first due to "relocating" the cecum into the right lower quadrant after which the reduction of small bowel back across the ileocecal valve then occurs.

Correction to: Pediatric ileocolic intussusception: new observations and unexpected implications.

In this article, the fourth author's name is misspelled. The correct spelling, as shown above, should be "Nadia F. Mahmood."

Latitude, temperature, and habitat complexity predict predation pressure in eelgrass beds across the Northern Hemisphere.

Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37° of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.

Unfounded conclusions of equivalence in diagnostic accuracy studies: a pervasive fallacy of inference in pediatric radiology scientific abstracts.

BACKGROUND: In studies of diagnostic performance that fail to detect a statistically significant difference between compared techniques, investigators often declare evidence of equivalence or similarity without having actually tested that assertion due to incorrect methodology or insufficient statistical power. OBJECTIVE: The purpose of our investigation is to measure the prevalence of unfounded assertions of equivalence or similarity in comparison studies presented at the International Pediatric Radiology (IPR) meeting of 2016 and promote awareness of this fallacy of inference to the pediatric radiology community. MATERIALS AND METHODS: Two pediatric radiologists independently reviewed the methodology and reporting quality of the 194 scientific paper abstracts from the 2016 IPR meeting. All comparison studies were identified and those failing to detect a statistically significance difference and making a claim of equivalence or similarity in the results or conclusion were assessed for a description of the study design type, statistical power and sample size estimator calculation. RESULTS: Of 194 scientific paper abstracts, 112 (58%) were comparison studies. Of these, 36/112 (32%) made unfounded inferences of equivalence or similarity in diagnostic imaging performance. No study had an equivalence or non-inferiority design. No abstract specified the statistical power of the study, and only one abstract acknowledged a small sample size as a limitation in detecting a statistically significant difference. CONCLUSION: Inadequate reporting and unfounded inferences of equivalence or similarity were common in diagnostic performance comparison studies presented at IPR 2016. Failure to recognize these limitations could have adverse consequences by leading to the adoption of unvalidated imaging techniques.

Modified Friedman technique: a new proposed method of measuring glenoid version in the setting of glenohumeral dysplasia.

BACKGROUND: Glenoid version angles are measured to objectively follow changes related to glenohumeral dysplasia in the setting of brachial plexus birth palsy. Measuring glenoid version on cross-sectional imaging was initially described by Friedman et al. in 1992. Recent literature for non-dysplastic shoulders advocates time-consuming reconstructions and reformations for an accurate assessment of glenoid version. OBJECTIVE: To compare Friedman's original method for measuring glenoid version to a novel technique we developed ("modified Friedman") with the reference standard of true axial reformations. MATERIALS AND METHODS: With institutional review board approval, we retrospectively examined 30 normal and dysplastic shoulders obtained from magnetic resonance imaging examinations of 30 patients with an established diagnosis of brachial plexus birth palsy between January 2012 and September 2017. Four pediatric radiologists performed glenoid version measurements using Friedman's method, the modified Friedman method and a previously described true axial reformation method. The modified Friedman technique better accounts for scapular positioning by selecting a reference point related to the acromion-scapular body interface. Inter-rater reliability and inter-method agreement were assessed using intraclass correlation, paired t-tests and mixed linear model analysis. Equivalence tests between methods were performed per reader. RESULTS: Glenoid version measurements were significantly different when comparing Friedman's method to true axial reformations in normal (-10.8±5.7° [mean±standard deviation] vs. -8.8±5.3°; P≤0.001) and dysplastic shoulders (-34.6±17.7° vs. -28.1±17.5°; P≤0.001). Glenoid version measurements were not significantly different when comparing the modified Friedman's method to true axial reformations in normal (-6.3±5.8° vs. -8.8±5.3°; P=0.06) and dysplastic shoulders (-29.0±18.3° vs. -28.1±17.5°; P=0.06). Friedman's method was not equivalent to true axial reformations for measurements in dysplastic shoulders for all readers (P=0.68, 0.81, 0.86, 0.99); the modified Friedman method was equivalent to of true axial reformations for measurements in dysplastic shoulders for 3 of 4 readers (P≤0.001, P≤0.001, P≤0.001, P=0.10). CONCLUSION: In glenohumeral dysplasia, the modified Friedman method and post-processed true axial reformations provide statistically similar and reproducible values. We propose that our modified Friedman technique can be performed in lieu of post-processed true axial reformations to generate glenoid version measurements.

Correction to: Comparative safety and efficacy of balloon use in air enema reduction for pediatric intussusception.

The original version on this paper contained an error. The names of M. John Hicks and R. Paul Guillerman, though correctly appeared in the published version, are incorrectly displayed in indexing sites.

Comparative safety and efficacy of balloon use in air enema reduction for pediatric intussusception.

BACKGROUND: Intussusception, a common cause of bowel obstruction in young children, is primarily treated with air enema reduction. There is little literature comparing the safety and efficacy of air reduction without or with a rectal balloon. OBJECTIVE: To determine the safety and efficacy of a rectal balloon seal in air enema reduction. MATERIALS AND METHODS: We retrospectively reviewed the records of children who underwent air reduction for ileocolic or ileo-ileocolic intussusception over an 8-year period. We sorted data from 566 children according to whether a rectal balloon was used in the reduction, and further sorted them by type and experience level of the practitioner. Using logistic regression analyses, we identified risk factors for iatrogenic bowel perforation or failed reduction. RESULTS: Significant associations with bowel perforation included balloon use (P=0.038), age <1 year (P<0.0001), and attending physician's level of experience <5 years (P=0.043). Younger age was associated with both perforation (P<0.0001) and procedural failure (P=0.001). The risk-adjusted predicted probability of perforation decreased with age, approaching zero by 10 months regardless of balloon use. For cases without bowel resection, the risk-adjusted predicted probability of failure decreased toward zero by 30 months with balloon use, while remaining constant at 3-12% regardless of age when not using a balloon. CONCLUSION: The likelihood of a successful air reduction might be safely increased by using an inflated rectal balloon in children older than 9 months. Use of a balloon in younger infants is associated with a higher risk of iatrogenic bowel injury.

How Long Does it Take to Diagnose Appendicitis? Time Point Process Mapping in the Emergency Department.

OBJECTIVES: Appendicitis is the most common surgical emergency encountered in the pediatric emergency department (ED). We analyzed the time course of children evaluated for suspected appendicitis in relation to implementation of a risk-stratified ultrasound scoring system and structured reporting template (Appy-Score). METHODS: In July 2013, a 6-level ultrasound (US)-based appendicitis scoring system was developed and implemented. The records of children (age ≤18 years) who underwent limited abdominal US exams for suspected appendicitis at a large academic pediatric ED were reviewed retrospectively. Time periods evaluated were from January 1 to April 1, 2013 (before implementation of the US scoring system, "PRE") and July 1 to October 1, 2013 (after implementation of the US scoring system, "POST"). Times are presented as medians with interquartile range. RESULTS: A total of 926 children were included (median age, 9.5 years [range, 0.1-18 years]; 49% female). Four hundred eighty-one patients were evaluated PRE and 445 POST. When comparing the 2 groups, there were no differences in the PRE and POST periods with regard to time from US ordered to first read (102 vs 112 minutes, P = 0.30), US ordered to disposition (215 vs 208 minutes, P = 0.40) and operating room posting (121 vs 122 minutes, P = 0.59), and overall ED stay (329 vs 333 minutes, P = 0.39). CONCLUSIONS: The development of a radiographic appendicitis score, although allowing for a standardized reporting method, did not significantly alter the ED process flow for evaluation of appendicitis. This reflects the complexities in ED throughput and reveals the need for additional factors to change to improve patient flow.

Diagnostic Performance of US for Differentiating Perforated from Nonperforated Pediatric Appendicitis: A Prospective Cohort Study.

Purpose To prospectively evaluate the diagnostic performance of ultrasonography (US) for differentiating perforated from nonperforated pediatric appendicitis and to investigate the association between specific US findings and perforation. Materials and Methods This HIPAA-compliant study had institutional review board approval, and the need for informed consent was waived. All abdominal US studies performed for suspected pediatric appendicitis at one institution from July 1, 2013, to July 9, 2014, were examined prospectively. US studies were reported by using a risk-stratified scoring system (where a score of 1 indicated a normal appendix; a score of 2, an incompletely visualized normal appendix; a score of 3, a nonvisualized appendix; a score of 4, equivocal; a score of 5a, nonperforated appendicitis; and a score of 5b, perforated appendicitis). The diagnostic performance of US studies designated 5a and 5b was calculated. The following US findings were correlated with perforation at multivariate analysis: maximum appendiceal diameter, wall thickness, loss of mural stratification, hyperemia, periappendiceal fat inflammation, periappendiceal fluid, lumen contents, and appendicolith presence. The number of symptomatic days prior to presentation was recorded. Surgical diagnosis and clinical follow-up served as reference standards. Results A total of 577 patients with a diagnosis of appendicitis at US met the study criteria (468 with a score of 5a; 109 with a score of 5b). Appendicitis was correctly identified in 573 (99.3%) of 577 patients. US performance in the detection of perforated appendicitis (5b) was as follows: a sensitivity of 44.0% (80 of 182), a specificity of 93.1% (364 of 391), a positive predictive value of 74.8% (80 of 107), and a negative predictive value of 78.1% (364 of 466). Statistically significant associations with perforated appendicitis were longer duration of symptoms (odds ratio [OR] = 1.46, P < .0001), increased maximum diameter (OR = 1.29, P < .0001), simple periappendiceal fluid (OR = 2.08, P = .002), complex periappendiceal fluid (OR = 18.5, P < .0001), fluid-filled lumen (OR = 0.34, P = .002), and appendicolith (OR = 1.67, P = .02). Conclusion US is highly specific but nonsensitive for perforated pediatric appendicitis. Several US findings are significantly associated with perforation, especially the presence of complex periappendiceal fluid. © RSNA, 2016.

Multiple stressors threaten the imperiled coastal foundation species eelgrass (Zostera marina) in Chesapeake Bay, USA.

Interactions among global change stressors and their effects at large scales are often proposed, but seldom evaluated. This situation is primarily due to lack of comprehensive, sufficiently long-term, and spatially extensive datasets. Seagrasses, which provide nursery habitat, improve water quality, and constitute a globally important carbon sink, are among the most vulnerable habitats on the planet. Here, we unite 31 years of high-resolution aerial monitoring and water quality data to elucidate the patterns and drivers of eelgrass (Zostera marina) abundance in Chesapeake Bay, USA, one of the largest and most valuable estuaries in the world, with an unparalleled history of regulatory efforts. We show that eelgrass area has declined 29% in total since 1991, with wide-ranging and severe ecological and economic consequences. We go on to identify an interaction between decreasing water clarity and warming temperatures as the primary drivers of this trend. Declining clarity has gradually reduced eelgrass cover the past two decades, primarily in deeper beds where light is already limiting. In shallow beds, however, reduced visibility exacerbates the physiological stress of acute warming, leading to recent instances of decline approaching 80%. While degraded water quality has long been known to influence underwater grasses worldwide, we demonstrate a clear and rapidly emerging interaction with climate change. We highlight the urgent need to integrate a broader perspective into local water quality management, in the Chesapeake Bay and in the many other coastal systems facing similar stressors.

Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems.

Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp. Zostera, P. gemini, or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts.