Oregon State University

About: Oregon State University is a education organization based out in Corvallis, Oregon, United States. It is known for research contribution in the topics: Population & Climate change. The organization has 28192 authors who have published 64044 publications receiving 2634108 citations. The organization is also known as: Oregon Agricultural College & OSU.

Geomorphic controls on hyporheic exchange flow in mountain streams

Abstract: [1] Hyporheic exchange flows were simulated using MODFLOW and MODPATH to estimate relative effects of channel morphologic features on the extent of the hyporheic zone, on hyporheic exchange flow, and on the residence time of stream water in the hyporheic zone. Four stream reaches were compared in order to examine the influence of stream size and channel constraint. Within stream reaches, the influence of pool-step or pool-riffle sequences, channel sinuosity, secondary channels, and channel splits was examined. Results showed that the way in which channel morphology controlled exchange flows differed with stream size and, in some cases, with channel constraint. Pool-step sequences drove hyporheic exchange in the second-order sites, creating exchange flows with relatively short residence times. Multiple features interacted to drive hyporheic exchange flow in the unconstrained fifth-order site, where pool-riffle sequences and a channel split created exchange flows with short residence times, whereas a secondary channel created exchange flows with long residence times. There was relatively little exchange flow in the bedrock-constrained fifth-order site. Groundwater flow models were effective in examining the morphologic features that controlled hyporheic exchange flow, and surface-visible channel morphologic features controlled the development of the hyporheic zone in these mountain streams.

The acute phase response and innate immunity of fish

Abstract: Tissue trauma or invasion by pathogens or parasites induce changes in the quantities of several macromolecules in animal body fluids These changes comprise one aspect of the acute phase response (APR), which in toto involves metabolic changes in several organ systems One clear indication of the response is the increase in synthesis and secretion by the liver of several plasma proteins, with simultaneous decreases in others These acute phase proteins (APP) function in a variety of defense-related activities such as limiting the dispersal of infectious agents, repair of tissue damage, inactivation of proteases, killing of microbes and other potential pathogens, and restoration of the healthy state Some APP are directly harmful to microbes, while others modify targets thus marking them for cell responses Some work alone while others contribute to cascades Proteins that are APP in mammals, and that have been identified in both teleosts and elasmobranchs include C-reactive protein, serum amyloid P, and several components of the Complement system Others reported in teleosts include transferrin and thrombin Of these, only CRP has been reported to increase in acute phase plasma In trout, a precerebellin-like protein is an APP with unknown functions A cDNA library enriched in fragments of transcripts that were more abundant in livers from fish undergoing an APR recently yielded sequences resembling 12 additional known APP, and as many others either not known to be APP, or not similar to others yet in public databases It appears that, as in mammals, hepatocytes are the prime source of APP in fish, and that pro-inflammatory cytokines induce transcription of their genes

The immediate effects of stress on hormones and plasma lysozyme in rainbow trout

Abstract: The fight-or-flight response prepares an animal for coping with alarming situations and their potential consequences, which include injury. The possible involvement of innate components of immunity in the response has received little attention. We determined plasma concentrations of stress hormones and lysozyme activity before and after a 10 min handling stressor. Rainbow trout (Oncorhynchus mykiss) were anesthetized in their home tanks, bled, revived, and then stressed by being held in the air in a net for 30 s and placed in a shallow bucket of water for 10 min. Fish were then captured, concussed (in one of two experiments) and bled again. Control fish were also bled twice, but were kept anesthetized in their holding tanks between bleedings. Following the stressor, plasma cortisol, adrenaline and lysozyme activity were significantly increased. The experiment was repeated 4 months later with a similar outcome. While chronic stress is eventually immunosuppressive, acute stress/trauma may help enhance both cellular and humoral components of innate defenses at times of likely need.

An Ecological Perspective of Riparian and Stream Restoration in the Western United States

Abstract: There is an unprecedented need to preserve and restore aquatic and riparian biological diversity before extinction eliminates the opportunity. Ecological restoration is the reestablishment of processes, functions, and related biological, chemical, and physical linkages between the aquatic and associated riparian ecosystems; it is the repairing of damage caused by human activities. The first and most critical step in ecological restoration is passive restoration, the cessation of those anthropogenic activities that are causing degradation or preventing recovery. Given the capacity of riparian ecosystems to naturally recover, often this is all that is needed to achieve successful restoration. Prior to implementation of active restoration approaches (e.g., instream structures, channel and streambank reconfiguration, and planting programs), a period of time sufficient for natural recovery is recommended. Unfortunately, structural additions and active manipulations are frequently undertaken without ha...