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131.
C. D. Dubischar E. A. Pakhomov L. von Harbou B. P. V. Hunt U. V. Bathmann 《Marine Biology》2012,159(1):15-24
Two species of salps, Salpa thompsoni and Ihlea racovitzai, were sampled during three cruises to the Lazarev Sea, Southern Ocean, in summer (December–January) 2005/2006, Autumn (April–May)
2004 and Winter (July–August) 2006. Dry weight, carbon, nitrogen, protein, lipid and carbohydrate contents were measured to
characterize the potential value of salps as a food source for predators in the Antarctic ecosystem. Biochemical composition
measurements showed that despite having a high percentage of water (~94% of wet weight), both species had relatively high
carbon and protein contents in their remaining dry weight (DW). In particular I. racovitzai showed high carbon (up to 22% of DW) and protein (up to 32% of DW) values during all seasons sampled, compared to lower values
for S. thompsoni (carbon content only about 15% of the DW, protein content about 10% of the DW). At the same time, carbohydrates (CH) and
lipids (Lip) only accounted for a small portion of salp DW in both species (1.4% CH and 3.6% Lip for I. racovitzai; 2.1% CH and 2.9% Lip for S. thompsoni). There was little variability in the biochemical composition of either salp species between the seasons sampled. Both biochemical
composition and life cycle characteristics suggest that Antarctic salps, especially I. racovitzai, may be important prey items for both cold and warm-blooded predators in an environment where food is often very scarce. 相似文献
132.
Network theory is commonly used to reveal social interactions and the organisation of interconnected nodes—but has not yet been applied to animal invasions. Non-native species invasions are now considered one of the foremost threats to natural ecosystems and biodiversity. This is the first attempt to assess social network properties within a freshwater fish assemblage invaded by a non-native fish species. We show that invasive sunbleak Leucaspius delineatus is socially more strongly interconnected with native species than the native species with each other. The social networks also reveal characteristics of a ‘small world’ such as low clustering coefficients C and short path lengths L. The findings may indicate potential traits of successful invaders and the implication for the spread of pathogens between individuals within a group of animals that contain a non-native invasive species. The success of establishment and subsequent invasion may be highlighted not only by the capacity of the new species to adapt to the new environment, but also in its capacity to penetrate the social circle of the native community. 相似文献
133.
Kathleen E. Hunt Thomas P. Hahn John C. Wingfield 《Behavioral ecology and sociobiology》1999,45(5):360-369
In males of socially monogamous birds, plasma testosterone (T) typically declines to low levels during the parental phase.
Studies on multiple-brooded species indicate that high T may be incompatible with high-quality paternal care. The length of
the breeding season may affect the costs and benefits of high T and its effect on paternal care. We studied the effect of
experimentally elevated T on paternal care in a single-brooded species with a short breeding season, the Lapland longspur
(Calcarius lapponicus). We monitored T levels and parental behavior in 16 males with subcutaneous T implants, 14 males with empty implants, and
14 unimplanted males. We videotaped nests when nestlings were 2–3 days old and again at 4–5 days. T males with 2- to 3-day-old
young visited nests and fed young less often than control males, and the mates of the T males compensated with elevated visits
and feedings. However, when nestlings were 4–5 days old, T males visited their nests at normal rates – though feeding movements
remained below normal – and T females visited and fed at normal rates. Nestling mass and nest success were similar in both
groups. Overall, high T suppresses paternal care in Lapland longspur males. The partial improvement of paternal care when
nestlings are older, despite high T, may be related to the short 6-week breeding season of this arctic species, and the consequently
reduced benefits of sexual behavior late in the breeding season.
Received: 2 February 1998 / Accepted after revision: 2 November 1998 相似文献
134.
Dennis Ojima Luis Garcia E. Elgaali Kathleen Miller Timothy G. F. Kittel Jill Lackett 《Journal of the American Water Resources Association》1999,35(6):1443-1454
ABSTRACT: This paper reports on the current assessment of climate impacts on water resources, including aquatic ecosystems, agricultural demands, and water management, in the U.S. Great Plains. Climate change in the region may have profound effects on agricultural users, aquatic ecosystems, and urban and industrial users alike. In the central Great Plains Region, the potential impacts of climate changes include changes in winter snowfall and snow-melt, growing season rainfall amounts and intensities, minimum winter temperature, and summer time average temperature. Specifically, results from general circulation models indicate that both annual average temperatures and total annual precipitation will increase over the region. However, the seasonal patterns are not uniform. The combined effect of these changes in weather patterns and average seasonal climate will affect numerous sectors critical to the economic, social and ecological welfare of this region. Research is needed to better address the current competition among the water needs of agriculture, urban and industrial uses, and natural ecosystems, and then to look at potential changes. These diverse demands on water needs in this region compound the difficulty in managing water use and projecting the impact of climate changes among the various critical sectors in this region. 相似文献
135.
136.
Bruce W. Hardy Kathleen Hall Jamieson 《Environmental Communication: A Journal of Nature and Culture》2017,11(2):205-217
Unusually cold winters, a slowing in upward global temperatures, or an increase in Arctic sea ice extent are often falsely cast as here-and-now disconfirmation of the scientific consensus on climate change. Such conclusions are examples of “end point bias,” the well documented psychological tendency to interpret a recent short-term fluctuation as a reversal of a long-term trend. End point bias poses a challenge to those trying to communicate cross-decade climate warming trends. In this study, we demonstrate that exposure to misleading scientific information on FoxNews.com that evokes end point bias can affect the beliefs of liberals and moderates as well as conservatives. We also show that the leveraging-involving-visualizing-analogizing communication model can reduce the effects of endpoint bias among moderates and liberals at the same time as it dampens both the ideological and endpoint biasing of conservatives. 相似文献
137.
Michael Hennessy Lauren Hawkins Kathleen Hall Jamieson 《Environmental Communication: A Journal of Nature and Culture》2017,11(1):63-74
In this article we examine in real time the political selective exposure process involved when the public confronted the “walrus haul out” of October 2014, a news event attributed by some climate change researchers to the effects of the climate change-driven reduction of Arctic sea ice. Analyzing data assessing the amount of major TV and cable news network coverage of the haul out, and evaluating public opinion data collected from a rolling cross-sectional survey of US adults take at the time, we show that coverage of this event was not equitably distributed across news media news sources, that exposure to news source is related to the respondents’ ideological dispositions, and that exposure to coverage of the walrus haul out is related to ideology, the selectivity of political news habits, and climate change knowledge. We conclude with a discussion of the apparent inevitability of selective exposure to media coverage of climate change-related events and the implications for effective climate change communication. 相似文献
138.
Kathleen L. Wolf Elizabeth Housley 《Journal of Environmental Planning and Management》2017,60(10):1853-1870
Decades of research studies demonstrate links between healthy environment, healthy lifestyles, and healthy people. This study evaluated the correlations between young adult conservation workers' perceived stress, personal effectiveness, and nature experience using quantitative and qualitative social science methods. The study cohort numbered nearly 300 individuals serving on small crews for an entire year, and were dispersed across Washington State (USA) to participate in conservation projects in rural to urban landscapes. Pre- and post-test surveys, using validated measures of perceived stress, health dimensions, and personal resiliency, were further informed by mid-year, field-based interviews. Overall, the young adults expressed fatigue with the physical work but were quite healthy when compared to national benchmarks. They indicated a reduction in perceived stress, and indicated social function influences based on the conservation work. Conclusions address the importance and implications of expanding this work opportunity to a more diverse cohort and future research needs. 相似文献
139.
A.R. Melwani S.N. Bezalel J.A. Hunt J.L. Grenier G. Ichikawa W. Heim A. Bonnema C. Foe D.G. Slotton J.A. Davis 《Environmental pollution (Barking, Essex : 1987)》2009,157(11):3137-3149
A three-year study was conducted to examine mercury in sport fish from the Sacramento–San Joaquin Delta. More than 4000 fish from 31 species were collected and analyzed for total mercury in individual muscle filets. Largemouth bass and striped bass were the most contaminated, averaging 0.40 μg/g, while redear sunfish, bluegill and rainbow trout exhibited the lowest (<0.15 μg/g) concentrations. Spatial variation in mercury was evaluated with an analysis of covariance model, which accounted for variability due to fish size and regional hydrology. Significant regional differences in mercury were apparent in size-standardized largemouth bass, with concentrations on the Cosumnes and Mokelumne rivers significantly higher than the central and western Delta. Significant prey–predator mercury correlations were also apparent, which may explain a significant proportion of the spatial variation in the watershed. 相似文献
140.