Geology topics

Robert Winfree

Publications and source records attributed to Robert Winfree.

3 recordsLinked to original sources

USGS2014

Predicting the effects of climate change on ecosystems and wildlife habitat in northwest Alaska

We used a modeling framework and a recent ecological land classification and land cover map to predict how ecosystems and wildlife habitat in northwest Alaska might change in response to increasing temperature. Our results suggest modest increases in forest and tall shrub ecotypes in Northwest Alaska by the end of this century thereby increasing habitat for forest-dwelling and shrub-using birds and mammals. Conversely, we predict declines in several more open low shrub, tussock, and meadow ecotypes favored by many waterbird, shorebird, and small mammal species.

Alaska↗

USGS1993

Chemical and nutritional evaluation of soya protein preparations as primary nitrogen sources for rainbow trout (Oncorhynchus mykiss)

Five soya-bean preparations that had been subjected to various physicochemical processing procedures were chemically defined in respect to proximate analysis, amino acid analyses, protease inhibitor activity, soluble oligosaccharides and antigenicity. These soya preparations were then formulated, along with a low-temperature fish meal control, into six isonitrogenous and isocaloric experimental diets. The diets were fed to rainbow trout ( Oncorhynchus mykiss ) in feeding trials as well as in tests using specially constructed metabolic chambers. Based on the chemical and biological results, we concluded that soya-bean oligosaccharides do not have to be removed or modified for maximum growth or nitrogen utilization by rainbow trout. Likewise, the protease or trypsin inhibitor activity, which was low for all experimental treatments, did not appear to be a major factor in determining fish performance. Although the results regarding naturally occurring soya antigens only suggested allergenicity, it is concluded that more attention should be focused on these heat-stable proteins with antigenic or allergenic potential in fish diets.

Animal Feed Science and Technology↗

USGS1992

Nutritional value of dietary nucleic acids and purine bases to rainbow trout (Oncorhynchus mykiss)

Rainbow trout were fed diets with graded levels (0.6%, 1.6%, 2.5%, and 4.1%) of a yeast nucleic acid extract corresponding to dietary Saccharomyces cerevisiae levels of 7.5%, 20%, 30% and 50% or diets supplemented isonitrogenously (0.8% N) with free purines (adenine, guanine, xanthine, and hypoxanthine) in two 12-week studies. Fish fed increasing levels of yeast extract manifested significant ( P < 0.05) corresponding incremental increases in growth and nitrogen retention. No negative effects on feed intake were observed. When fish were fed supplemental free purines, adenine was shown to be a potent inhibitor of feed intake and growth. While supplementation with the remaining purines did not negatively affect feed intake or growth, carcass nitrogen retention was significantly depressed, indicating the lack of a nitrogen-sparing effect. Our results indicate that the nutritional significance of free dietary adenine versus nucleic acid-bound adenine in yeast or yeast nucleic acid is an important consideration in evaluating the suitability of single cell proteins in fish feed formulations.

Aquaculture↗