Forest-Stream Linkages: Effects of Terrestrial Invertebrate Input and Light on Diet and Growth of Brown Trout (Salmo trutta) in a Boreal Forest Stream

Subsidies of energy and material from the riparian zone have large impacts on recipient stream habitats. Human-induced changes, such as deforestation, may profoundly affect these pathways. However, the strength of individual factors on stream ecosystems is poorly understood since the factors involved often interact in complex ways. We isolated two of these factors, manipulating the flux of terrestrial input and the intensity of light in a 2×2 factorial design, where we followed the growth and diet of two size-classes of brown trout (Salmo trutta) and the development of periphyton, grazer macroinvertebrates, terrestrial invertebrate inputs, and drift in twelve 20 m long enclosed stream reaches in a five-month-long experiment in a boreal coniferous forest stream. We found that light intensity, which was artificially increased 2.5 times above ambient levels, had an effect on grazer density, but no detectable effect on chlorophyll a biomass. We also found a seasonal effect on the amount of drift and that the reduction of terrestrial prey input, accomplished by covering enclosures with transparent plastic, had a negative impact on the amount of terrestrial invertebrates in the drift. Further, trout growth was strongly seasonal and followed the same pattern as drift biomass, and the reduction of terrestrial prey input had a negative effect on trout growth. Diet analysis was consistent with growth differences, showing that trout in open enclosures consumed relatively more terrestrial prey in summer than trout living in covered enclosures. We also predicted ontogenetic differences in the diet and growth of old and young trout, where we expected old fish to be more affected by the terrestrial prey reduction, but we found little evidence of ontogenetic differences. Overall, our results showed that reduced terrestrial prey inputs, as would be expected from forest harvesting, shaped differences in the growth and diet of the top predator, brown trout

Consensus statement on abusive head trauma in infants and young children

Abusive head trauma (AHT) is the leading cause of fatal head injuries in children younger than 2 years. A multidisciplinary team bases this diagnosis on history, physical examination, imaging and laboratory findings. Because the etiology of the injury is multifactorial (shaking, shaking and impact, impact, etc.) the current best and inclusive term is AHT. There is no controversy concerning the medical validity of the existence of AHT, with multiple components including subdural hematoma, intracranial and spinal changes, complex retinal hemorrhages, and rib and other fractures that are inconsistent with the provided mechanism of trauma. The workup must exclude medical diseases that can mimic AHT. However, the courtroom has become a forum for speculative theories that cannot be reconciled with generally accepted medical literature. There is no reliable medical evidence that the following processes are causative in the constellation of injuries of AHT: cerebral sinovenous thrombosis, hypoxic-ischemic injury, lumbar puncture or dysphagic choking/vomiting. There is no substantiation, at a time remote from birth, that an asymptomatic birth-related subdural hemorrhage can result in rebleeding and sudden collapse. Further, a diagnosis of AHT is a medical conclusion, not a legal determination of the intent of the perpetrator or a diagnosis of murder. We hope that this consensus document reduces confusion by recommending to judges and jurors the tools necessary to distinguish genuine evidence-based opinions of the relevant medical community from legal arguments or etiological speculations that are unwarranted by the clinical findings, medical evidence and evidence-based literature

Patterns of river influence and connectivity among subbasins of Puget Sound, with application to bacterial and nutrient loading

Puget Sound is an estuarine inland sea fed by 14 major rivers and also strongly influenced by the nearby Fraser River. A comprehensive, particle-based reanalysis of an existing circulation model was used to map the area of influence of each of these rivers over a typical seasonal cycle. Each of the 131,000 particles released in the 15 rivers was associated with a freshwater volume, a nutrient load, and a fecal coliform load based on statistics from 10 years of Washington Department of Ecology monitoring data. Simple assumptions regarding mortality and nutrient utilization/export rates were used to estimate the decrease in bacterial and nutrient load as individual parcels of river water age. Reconstructions of basin-scale volume fluxes and salinities from the particle inventory provide consistency checks on the particle calculation, according to methods suitable for error analysis in a wide range of particle-based estuarine residence time studies. Results suggest that river contributions to total freshwater content in Puget Sound are highly nonlocal in spring and summer, with distant, large rivers (the Fraser and Skagit) accounting for a large fraction of total freshwater. However, bacterial mortality and nutrient export rates are relatively fast compared with transport timescales, and so significant loadings associated with major rivers are in most cases only seen close to river mouths. One notable exception is fecal coliform concentration in Bellingham Bay and Samish Bay, which lie north of Puget Sound proper; there, it appears that the Fraser River may rival local rivers (the Samish and Nooksack) as a pathogen source, with the much higher flow volume of the Fraser compensating for its remoteness