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ABSTRACT Recolonization by native species following reintroduction can affect resident species through a variety of processes. We examined the effects of natural recolonization by coho salmon Oncorhynchus kisutch on sculpin ( Cottus rhotus and Cottus gulosus), small benthic fishes, in a small forest stream in Western Washington, USA. Provision fish passage around a small dam allowed coho access to habitat, which had been inaccessible for over 100 years. We found that density (g m−2 and number m−2) was unchanged, and body condition (the slope of the relationship between length and weight) of sculpin tended to increase from before relative to a 5-year period following recolonization. The proportion of sculpin comprising the total fish assemblage decreased after coho colonization relative to before but remained stable for a 5-year period after coho reintroduction, whereas coho density increased over fivefold. Additionally, we used Akaike's information criteria to evaluate the relative importance of physical and biological variables to predict sculpin density in pool habitats during the initial coho recolonization period. Physical microhabitat variables had little support for predicting sculpin density, whereas there was a significant support for stream temperature; cutthroat trout ( Oncorhynch us clarkii) density and year were the most important predictors of sculpin density. Coho density was not significant in any model. Our results indicate coho introduction and subsequent recolonization have to date had minimal individual or population level effects on sculpin, therefore demonstrating that species reintroductions into their native range can have no measurable effect on resident organisms. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT Engineered log jams (ELJs) are increasingly being used in large rivers to create fish habitat and as an alternative to riprap for bank stabilization. However, there have been few studies that have systematically examined how juvenile salmonids utilized these structures relative to other available habitat. We examined Chinook salmon ( Oncorhynchus tshawytscha), coho salmon ( O. kisutch) and trout ( O. mykiss and O. clarki) response to the placement of engineered log jams (ELJs) in the Elwha River, Washington State, USA. We used summer snorkel surveys and a paired control-treatment design to determine how engineered log jams in a large river system affect the density of juvenile salmon. We hypothesized that densities of juvenile salmonids would be greater in habitats with ELJs than in habitats without ELJs in the Elwha River and that this ELJ effect would vary by species and size class. Juvenile salmonid density was higher in ELJ units for all control-treatment pairs except for one pair in 2002 and one pair in 2003. Positive mean differences in juvenile salmon densities between ELJ and non-ELJ units were observed in two of four years for all juvenile salmon, trout greater than 100 mm and juvenile Chinook salmon. Positive mean differences occurred in one of 4 years for juvenile coho salmon and trout less than 100 mm. The results suggest that ELJs are potentially useful for restoring juvenile salmon habitat in the Elwha River, Washington State, USA. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To investigate the time course and mechanisms of fetal O2 deprivation, we exposed 93 near-term, pregnant rabbits and their fetuses in utero to intermittent hypoxia. We administered a gas mixture containing 3, 4, 5 or 6 per cent O2 in N2 to a rabbit for 0.5, 1, 2, or 3 minutes, alternately with a recovery period of air breathing of 0.5, 1, 2, or 3 minutes. A given cyclical pattern was continued for 2 hours and fetal survival recorded 1 hour thereafter. Fetal survival decreased significantly at lower O2 levels, longer durations of exposure, and shorter durations of recovery intervals between exposures. Chances for survival were significantly greater among fetuses located at either end of the uterine horn.

The purpose of this study was to determine the placental diffusing capacity of CO in unanesthetized rabbits. A standard dose of CO was administered to 18 near-term rabbits, and at time intervals varying from 5 min to 4 h maternal and fetal blood samples were analyzed for carboxyhemoglobin saturation (HbCO). Following administration of CO, the maternal HbCO rose rapidly within the 1st min and remained nearly constant for the remainder of the experiment. The fetal HbCO after CO introduction to the mother rose as CO crossed the placenta from maternal to fetal blood. After 15 min the fetal HbCO rose to equal the maternal HbCO averaging 18.5%. The fetal HbCO after 1 h averaged 33% saturation, 1.7-fold greater than the maternal HbCO at 1 h. Thereafter there was little further fetal rise and apparently equilibrium was reached. The average placental diffusing capacity for CO was 2.3 ml/(min times mmHg times kg), a value fourfold higher than has previously been reported in anesthetized sheep and dogs. Possible reasons are species difference, effects of posture, influence of anesthesia and surgery, and effects of an open versus intact uterus.