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61.
J. Ashley T. Booth Henry A. Ruhl Lawrence L. Lovell David M. Bailey Kenneth L. SmithJr 《Marine Biology》2008,154(6):933-941
The 17-year time-series study at Station M in the NE Pacific has provided one of the longest datasets on deep-sea ophiuroids
to date. Station M is an abyssal site characterized by low topographical relief and seasonal and interannual variation in
surface-derived food inputs. From 1989 to 2005, over 31,000 ophiuroid specimens were collected. Size–frequency distributions
of the four dominant species, Ophiura bathybia, Amphilepis patens, Amphiura carchara and Ophiacantha
cosmica, were examined for recruitment and the role of surface-derived food supplies on body size distributions. Juveniles were collected
in sediment traps and used to investigate settlement patterns and seasonality. Trawl samples showed no indication of seasonal
changes in recruitment to larger size classes; however, there was evidence of seasonal settling of juveniles. Interannual
differences in median disk diameters and size distributions of trawl-collected adults are greater than those at the seasonal
scale. Three of the four species, O. bathybia, A. patens and O.
cosmica, had co-varying monthly median disk diameters, suggesting they may have a similar factor(s) controlling their growth and
abundance. Interannual differences in monthly size distributions were generally greater than those between seasons. Cross-correlations
between the particulate organic carbon (POC) flux (food supply) and size distribution indices for O. bathybia, A. patens and O.
cosmica all were significant indicating that increases in food supply were followed by increases in the proportion of smaller size
classes after approximately 17–22 months. These findings suggest that food inputs are indeed an important factor influencing
deep-sea ophiuroid populations on interannual time scales, more generally supporting the long-hypothesized connection between
food availability and population size structure in the deep sea.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
62.
Many symbioses involve multiple partners in complex, multi-level associations, yet little is known concerning patterns of
nutrient transfer in multi-level marine mutualisms. We used the anemonefish symbiosis as a model system to create a balance
sheet for nitrogen production and transfer within a three-way symbiotic system. We quantified diel patterns in excretion of
ammonia by anemonefish and subsequent absorption by host sea anemones and zooxanthellae under laboratory conditions. Rates
of ammonia excretion by the anemonefish Amphiprion bicinctus varied from a high of 1.84 μmole g−1 h−1 at 2 h after feeding, to a basal rate of 0.50 μmole g−1 h−1 at 24–36 h since the last meal. Conversely, host sea anemones Entacmaea quadricolor absorbed ammonia at a rate of 0.10 μmole g−1 h−1 during the daytime in ammonia-enriched seawater, but during the night reduced their absorption rate to near zero, indicating
that ammonia uptake was driven by zooxanthella photosynthesis. When incubated together, net ammonia excretion was virturally
zero, indicating that host anemones absorbed most of the ammonia produced by resident fish. Adult anemonefish weighed about
11 g under laboratory conditions, but on the coral reef may reach up to 64 g, resulting in a maximal potential ammonia load
of >200 μmole h−1 produced by two adult fish during daylight hours. In contrast, host sea anemones weighed about 47 g in the laboratory, but
under field conditions, large individuals may reach 680 g, so their maximal ammonia clearance rates may reach about 70 μmole h−1 during the daytime. As such, the ammonia load produced by adult anemonefish far exceeds the clearance rate of host anemones
and zooxanthellae. Ammonia transfer likely occurs mainly during the daytime, when anemonefish consume zooplankton and excrete
rapidly, and in turn the zooxanthellae are photosynthetically active and drive rapid ammonia uptake. We conclude that zooplanktivorous
fishes that form mutualisms with coral reef cnidarians may serve as an important link between open water and benthic ecosystems,
through the transfer of large quantities of nutrients to zooxanthellate hosts, thus enhancing coral reef productivity. 相似文献
63.
Occurrence and fate of pesticides in four contrasting agricultural settings in the United States 总被引:1,自引:0,他引:1
Steele GV Johnson HM Sandstrom MW Capel PD Barbash JE 《Journal of environmental quality》2008,37(3):1116-1132
Occurrence and fate of 45 pesticides and 40 pesticide degradates were investigated in four contrasting agricultural settings--in Maryland, Nebraska, California, and Washington. Primary crops included corn at all sites, soybeans in Maryland, orchards in California and Washington, and vineyards in Washington. Pesticides and pesticide degradates detected in water samples from all four areas were predominantly from two classes of herbicides--triazines and chloroacetanilides; insecticides and fungicides were not present in the shallow ground water. In most samples, pesticide degradates greatly exceeded the concentrations of parent pesticide. In samples from Nebraska, the parent pesticide atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] was about the same concentration as the degradate, but in samples from Maryland and California atrazine concentrations were substantially smaller than its degradate. Simazine [6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine], the second most detected triazine, was detected in ground water from Maryland, California, and Washington. Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] rarely was detected without its degradates, and when they were detected in the same sample metolachlor always had smaller concentrations. The Root-Zone Water-Quality Model was used to examine the occurrence and fate of metolachlor at the Maryland site. Simulations accurately predicted which metolachlor degradate would be predominant in the unsaturated zone. In analyses of relations among redox indicators and pesticide variance, apparent age, concentrations of dissolved oxygen, and excess nitrogen gas (from denitrification) were important indicators of the presence and concentration of pesticides in these ground water systems. 相似文献
64.
We demonstrate an approach for evaluating the level of protection attained using a variety of forms and levels of past, current,
and proposed Air Quality Standards (AQSs). The U.S. Clean Air Act requires the establishment of ambient air quality standards
to protect health and public welfare. However, determination of attainment of these standards is based on ambient pollutant
concentrations rather than prevention of adverse effects. To determine if a given AQS protected against adverse effects on
vegetation, hourly ozone concentrations were adjusted to create exposure levels that “just attain” a given standard. These
exposures were used in combination with a physiologically-based tree growth model to account for the interactions of climate
and ozone. In the evaluation, we used ozone concentrations from two 6-year time periods from the San Bernardino Mountains
in California. There were clear differences in the level of vegetation protection achieved with the various AQSs. Based on
modeled plant growth, the most effective standards were the California 8-hr average maximum of 70 ppb and a seasonal, cumulative,
concentration-weighted index (SUM06), which if attained, resulted in annual growth reductions of 1% or less. Least effective
was the 1-hr maximum of 120 ppb which resulted in a 7% annual reduction. We conclude that combining climate, exposure scenarios,
and a process-based plant growth simulator was a useful approach for evaluating effectiveness of current or proposed air quality
standards, or evaluating the form and/or level of a standard based on preventing adverse growth effects. 相似文献
65.
环境表现对金融利害攸关者的价值 总被引:1,自引:0,他引:1
Evan C.Henry 《生态毒理学报》2000,22(1):11-12
公司财务表现与环境表现之间的联系日益明显.各公司可以通过促进后者而力求获得资助优势.公司环境表现对金融利害攸关者的价值随资助类型而异,同样也随环境改善的程度和具体细节而异.争取资助的公司,以及政府和非政府组织,应当熟悉不同的金融服务业及其具体需要和问题. 相似文献
66.
67.
This paper summarizes research evaluating nitrate levels in shallow groundwater of upstate New York, USA. Water from abandoned dug wells in six different land-use categories was analyzed for nitrate. Findings indicate that regardless of overlying land-use, shallow groundwater is susceptible to high levels of nitrate. Over 60 percent of the water samples tested, including at least one sample from each land-use category, had nitrate levels in excess of the United States drinking water standard of 10 mg 1–1. Due to the potential threat of elevated nitrate levels, efforts should be made to eliminate abandoned dug wells in shallow groundwater as a source of water supply.Glenn Harris is with the Environmental Studies Programme of St Lawrence University in Canton, New York. Brian Henry is with the Department of Entomology at the University of Georgia in Athens, Georgia. Jeffrey Deyette is with the joint International Relations and Resource and Environmental Management Programme at Boston University in Boston, Massachusetts. This research was performed as a Community Service Project sponsored by the Mergardt Fund while Mr Henry and Mr Deyette were students under the supervision of Dr Harris at St Lawrence University. 相似文献
68.
Probability plots of trace element concentrations may be used to partition, or segregate, sample data into its constituent
populations. Two populations are typically present in data from sites requiring remedial action, one representing clean, uncontaminated
soil or sediment (background) and the other representing contaminated ground. The use of such plots in the analysis and evaluation
of environmental data permits a statistical characterization of the background populations, from which defensible cleanup
criteria may be developed. These criteria will be environmentally conservative, yet will minimize the amount of soil removed
in a remedial action. An example is given from a successful cleanup of a surface impoundment. 相似文献
69.
Marie Boehm Henry Janzen Bob MacGregor Murray Fulton 《Mitigation and Adaptation Strategies for Global Change》2004,9(4):503-504
Subject Index
Subject Index 相似文献70.
Venema Henry D. Schiller Eric J. Bass Brad 《Mitigation and Adaptation Strategies for Global Change》1996,1(2):139-165
The ongoing drought in the Sahel region of West Africa highlights the vulnerability of food-producing systems to climate change
and variability. Adaptation to climate should therefore increase the sustainability of agriculture under a long-term drought.
Progress towards sustainability and adaptation in the the Senegal River Basin is hampered by an existing set of social and
ecological relationships that define the control over the means of production and how people interact with their environment.
These relationships are sensitive to the technological inputs and the administration of food production, or the factor bias
in the different policy alternatives for rural development. One option is based on state-controlled, irrigated plantations
to provide rice (Oryza) for the capital, Dakar. This policy emphasizes a top-down management approach, mechanized agriculture and a reliance on
external inputs which strengthens the relationships introduced during the colonial period.
A time series decomposition of the annual flow in the Senegal River at Bakel in Senegal suggests that water resources availability
has been substantially curtailed since 1960, and a review of the water resources budget or availability in the basin suggests
that this policy's food production system is not sustainable under the current climate of the basin. Under these conditions,
this program is exacerbating existing problems of landscape degradation and desertification, which increases rural poverty.
A natural resource management policy offers two adaptation strategies that favour decentralized management and a reduction
of external inputs. The first alternative, “Les Perimetres Irrigués”, emphasizes village-scale irrigation, low water consumption
cereal crops and traditional socio-political structures. The second alternative emphasizes farm-level irrigation and agro-forestry
projects to redress the primary effects of desertification. 相似文献