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401.
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403.
Dover sole (Solea solea, Linneaus 1758) were raised from first feeding on brine shrimp (Artemia sp.) with different contents and compositions of the essential fatty acids (EFA) arachidonic acid (ARA, 20:4n − 6); eicosapentaenoic acid (EPA, 20:5n − 3), and docosahexaenoic acid (DHA, 22:6n − 3), and their metabolic rate and tolerance to hypoxia measured prior to and following metamorphosis and settlement. Four
dietary Artemia preparations were compared: (1) un-enriched; (2) enriched with a commercial EFA mixture (Easy DHA SELCO Emulsion); (3) enriched
with a marine fish oil combination (VEVODAR and Incromega DHA) to provide a high ratio of ARA to DHA, and (4) enriched with
these fish oils to provide a low ratio of ARA to DHA. Sole fed un-enriched Artemia were significantly less tolerant to hypoxia than the other dietary groups. Larvae from this group had significantly higher
routine metabolic rate (RMR) in normoxia, and significantly higher O2 partial pressure (PO2) thresholds in progressive hypoxia for their regulation of RMR (P
crit) and for the onset of agitation, respiratory distress and loss of equilibrium. Metamorphosis was associated with an overall
decline in RMR and increase in P
crit, but juveniles fed on un-enriched Artemia still exhibited higher P
crit and agitation thresholds than the other groups. Sole fed un-enriched Artemia had significantly lower contents of EFA in their tissues, both before and after settlement. Thus, enriching live feeds with
EFA has significant effects on the respiratory physiology of sole early life stages and improves their in vivo tolerance to
hypoxia. We found no evidence, however, for any effect of the ratio of ARA to DHA. 相似文献
404.
Jeff Joireman Donelle C. Posey Heather Barnes Truelove Craig D. Parks 《Journal of environmental psychology》2009,29(2):181-192
Three studies examined the impact of warnings about depleting resources. In Study 1, participants played 16 trials of a 5-person resource dilemma game with complete resource uncertainty. After trial 12, participants were told they were close to depleting the resource, and thereafter received no additional warnings. Size of harvests dropped after the warning, but rebounded within 3 trials to pre-warning levels, a pattern stronger under low harvesting variability. In Study 2, participants received warnings after trials 12 and 16 of a 22-trial game. Again, harvesting dropped after the first warning, but rebounded to pre-warning levels within 3 trials, a pattern stronger under a short-term vs. a long-term warning. Harvesting was unaffected by the second warning. In Study 3, when participants received no feedback about others' harvests, harvesting dropped after both warnings, and was lower among those led to believe the resource would last a short number of trials. 相似文献
405.
Global change affects alpine ecosystems by, among many effects, by altering plant distributions and community composition.
However, forecasting alpine vegetation change is challenged by a scarcity of studies observing change in fixed plots spanning
decadal-time scales. We present in this article a probabilistic modeling approach that forecasts vegetation change on Niwot
Ridge, CO using plant abundance data collected from marked plots established in 1971 and resampled in 1991 and 2001. Assuming
future change can be inferred from past change, we extrapolate change for 100 years from 1971 and correlate trends for each
plant community with time series environmental data (1971–2001). Models predict a decreased extent of Snowbed vegetation and
an increased extent of Shrub Tundra by 2071. Mean annual maximum temperature and nitrogen deposition were the primary a posteriori
correlates of plant community change. This modeling effort is useful for generating hypotheses of future vegetation change
that can be tested with future sampling efforts. 相似文献
406.
Vyas NB Spann JW Hulse CS Gentry S Borges SL 《Environmental monitoring and assessment》2007,133(1-3):209-214
The US Environmental Protection Agency conducts risk assessments of insecticide applications to wild birds using a model that
is limited to the dietary route of exposure. However, free-flying birds are also exposed to insecticides via the inhalation
and dermal routes. We measured azinphos-methyl residues on the skin plus feathers and the feet of brown-headed cowbirds (Molothrus ater) in order to quantify dermal exposure to songbirds that entered and inhabited an apple (Malus x domestica) orchard following an insecticide application. Exposure to azinphos-methyl was measured by sampling birds from an aviary
that was built around an apple tree. Birds sampled at 36 h and 7-day post-application were placed in the aviary within 1 h
after the application whereas birds exposed for 3 days were released into the aviary 4-day post-application. Residues on vegetation
and soil were also measured. Azinphos-methyl residues were detected from the skin plus feathers and the feet from all exposure
periods. Our results underscore the importance of incorporating dermal exposure into avian pesticide risk assessments. 相似文献
407.
Gurpal S. Toor Lu Han Craig D. Stanley 《Environmental monitoring and assessment》2013,185(5):4305-4320
Our objective was to evaluate changes in water quality parameters during 1983–2007 in a subtropical drinking water reservoir (area: 7 km2) located in Lake Manatee Watershed (area: 338 km2) in Florida, USA. Most water quality parameters (color, turbidity, Secchi depth, pH, EC, dissolved oxygen, total alkalinity, cations, anions, and lead) were below the Florida potable water standards. Concentrations of copper exceeded the potable water standard of <30 μg?l?1 in about half of the samples. About 75 % of total N in lake was organic N (0.93 mg?l?1) with the remainder (25 %) as inorganic N (NH3-N: 0.19, NO3-N: 0.17 mg?l?1), while 86 % of total P was orthophosphate. Mean total N/P was <6:1 indicating N limitation in the lake. Mean monthly concentration of chlorophyll-a was much lower than the EPA water quality threshold of 20 μg?l?1. Concentrations of total N showed significant increase from 1983 to 1994 and a decrease from 1997 to 2007. Total P showed significant increase during 1983–2007. Mean concentrations of total N (n?=?215; 1.24 mg?l?1) were lower, and total P (n?=?286; 0.26 mg?l?1) was much higher than the EPA numeric criteria of 1.27 mg total N l?1 and 0.05 mg total P l?1 for Florida’s colored lakes, respectively. Seasonal trends were observed for many water quality parameters where concentrations were typically elevated during wet months (June–September). Results suggest that reducing transport of organic N may be one potential option to protect water quality in this drinking water reservoir. 相似文献
408.
Carrie Nelms Myria W. Allen Christopher A. Craig Shelby Riggs 《Environmental Communication: A Journal of Nature and Culture》2017,11(4):537-553
There has been an increase in scholarly attention to adolescents’ environmental attitudes; however, only a small number of empirical studies address the Adolescent Environmentalist’s (AE) personal and collective identity, media usage, and communication orientation. In this study, we investigate differences in young people (aged 12–17) who identify themselves as environmentalists, or the AEs, and those who do not drawing from a national sample of 1096 youth. Results show AEs significantly differ from their peers. The AEs have a different environmental value set, report greater self-confidence and influence among peers, support the stronger display of citizenship behaviors, follow certain news topics more, use and discuss the news more with a variety of others, and report engaging in more dialogue and persuasion. 相似文献
409.
Elizabeth B. Connelly Craig R. Allen Kirk Hatfield José M. Palma-Oliveira David D. Woods Igor Linkov 《The Environmentalist》2017,37(1):46-50
The National Academy of Sciences (NAS) definition of resilience is used here to organize common concepts and synthesize a set of key features of resilience that can be used across diverse application domains. The features in common include critical functions (services), thresholds, cross-scale (both space and time) interactions, and memory and adaptive management. We propose a framework for linking these features to the planning, absorbing, recovering, and adapting phases identified in the NAS definition. The proposed delineation of resilience can be important in understanding and communicating resilience concepts. 相似文献
410.
The Great Lakes Hydrography Dataset: Consistent,Binational Watersheds for the Laurentian Great Lakes Basin 下载免费PDF全文
Danielle K. Forsyth Catherine M. Riseng Kevin E. Wehrly Lacey A. Mason John Gaiot Tom Hollenhorst Craig M. Johnston Conrad Wyrzykowski Gust Annis Chris Castiglione Kent Todd Mike Robertson Dana M. Infante Lizhu Wang James E. McKenna Gary Whelan 《Journal of the American Water Resources Association》2016,52(5):1068-1088
Ecosystem‐based management of the Laurentian Great Lakes, which spans both the United States and Canada, is hampered by the lack of consistent binational watersheds for the entire Basin. Using comparable data sources and consistent methods, we developed spatially equivalent watershed boundaries for the binational extent of the Basin to create the Great Lakes Hydrography Dataset (GLHD). The GLHD consists of 5,589 watersheds for the entire Basin, covering a total area of approximately 547,967 km2, or about twice the 247,003 km2 surface water area of the Great Lakes. The GLHD improves upon existing watershed efforts by delineating watersheds for the entire Basin using consistent methods; enhancing the precision of watershed delineation using recently developed flow direction grids that have been hydrologically enforced and vetted by provincial and federal water resource agencies; and increasing the accuracy of watershed boundaries by enforcing embayments, delineating watersheds on islands, and delineating watersheds for all tributaries draining to connecting channels. In addition, the GLHD is packaged in a publically available geodatabase that includes synthetic stream networks, reach catchments, watershed boundaries, a broad set of attribute data for each tributary, and metadata documenting methodology. The GLHD provides a common set of watersheds and associated hydrography data for the Basin that will enhance binational efforts to protect and restore the Great Lakes. 相似文献