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241.
242.
Summary Male giant waterbugs (Belostoma flumineum Say) brood eggs oviposited on their dorsa by conspecific females. Laboratory observations indicate that viable egg pads are occasionally discarded before hatching. Theory predicts that such behavior should occur only if the costs incurred by brooding exceed the benefits of hatching the egg pad. We studied the effects of egg pad size, time invested in brooding, and egg viability upon the continuation of paternal care in the giant waterbug. We found that smaller egg pads are less likely to hatch than larger ones, and males appear to be less likely to discard egg pads as temporal investment increases. However, the inviability of eggs did not appear to affect the probability of an egg pad being discarded. Males of this species appear to have evolved a decision-making process involving the continuation of paternal care.
Offprint requests to: K.C. Kruse 相似文献
243.
During oil and gas production, water is often extracted from geological formations along with the hydrocarbons. These "produced
waters" have been discharged to Nueces Bay since the turn of the century. These effluents were found to be highly toxic, and
sediments in the vicinity of the discharges were also toxic. We developed a map of wells and produced-water discharge sites
in the vicinity of Nueces Bay and identified numerous unplugged wells suitable for conversion to produced water disposal wells.
An economic analysis of conversion to subterranean injection of produced water indicates that most of the wells currently
in production could pay out the cost of conversion to injection in one to three years. The use of one injection well for two
or more water-producing wells could yield greater savings. Wells that could not support the cost of injection are small producers,
and their loss would not constitute a major loss of jobs or dollars to the area. This study could serve as a useful model
for evaluating the economic feasibility of conversion to injection in other areas of Texas and Louisiana. 相似文献
244.
Climate change adaptation in the ski industry 总被引:4,自引:0,他引:4
Daniel Scott Geoff McBoyle 《Mitigation and Adaptation Strategies for Global Change》2007,12(8):1411-1431
Regardless of the success of climate change mitigation efforts, the international community has concluded that societies around
the world will need to adapt to some magnitude of climate change in the 21st century. While some economic sectors (e.g., agriculture,
water resources and construction) have been actively engaged in climate change adaptation research for years, adaptation has
received scant consideration within the tourism-recreation industry. This is particularly the case for adaptation by tourism
operators (supply-side). One exception where progress on supply-side climate adaptation has been made is the ski industry.
This paper provides a brief overview of the literature on the implications of climate change for the international ski industry
and how adaptation by ski area operators has been treated within these studies. This is followed by an inventory of climate
adaptation practices currently used by ski industry stakeholders, including the historical development of certain key adaptations
and constraints to wider use. The characteristics of ski areas with higher adaptive capacity are identified. Considering the
highly competitive nature of the ski industry and the generally low climate change risk appraisal within the industry, climate
change adaptation is anticipated to remain individualistic and reactive for some time. With only a few exceptions, the existing
climate change literature on winter tourism has not considered the wide range of adaptation options identified in this paper
and has likely overestimated potential damages. An important task for future studies is to develop methodologies to incorporate
adaptation so that a more accurate understanding of the vulnerability of the international ski industry can be ascertained. 相似文献
245.
Inferring Threat from Scientific Collections 总被引:3,自引:1,他引:3
Exact formulas for the probability of extinction or change in the conservation status of species are described for data based on frequency of sighting. These formulas generalize an expression previously described for the probability of extinction from (binary) sighting data. The formulas will be used in contexts where sightings are recorded as frequencies, such as when observations are aggregated in time. We argue that computing the probability of extinction or change in conservation status will be most useful for setting conservation priorities and in screening large data sets contained in museum and herbarium collections and in biological resource inventories. 相似文献
246.
Two heavy metal-binding proteins occur naturally in the midgut glands of Carcinus maenas (L.) collected from the Firth of Clyde, Scotland. These proteins, of approximately 27,000 and 11,500 MW (molecular weight) have previously been described as Cd-binding proteins after their induction by high concentrations of cadmium in the laboratory. The 27,000 MW heavy metal-binding protein is bound to about 0.10 g-at of Cd, 0.70 g-at of Zn and 0.31 g-at of Cu per mole of protein; 7.7, 7.9 and 1.1%, respectively, of the soluble Cd, Zn and Cu in the midgut gland are associated with this 27,000 MW protein (6.7, 1.6 and 0.9% of the total midgut gland Cd, Zn and Cu). The 11,500 MW protein is bound to about 0.04 g-at of Cd, 0.37 g-at of Zn and 1.54 g-at of Cu per mole of protein; 29.3, 31.3 and 41.7%, respectively, of the soluble Cd, Zn and Cu in the midgut gland are associated with this protein (25.7, 6.3 and 34.4% of the total midgut gland Cd, Zn and Cu). Neither heavy metal-binding protein is bound to measurable amounts of lead. 相似文献
247.
Laurie B. Connell Scott P. MacQuarrie Betty M. Twarog Melissa Iszard V. Monica Bricelj 《Marine Biology》2007,150(6):1227-1236
The softshell clam, Mya arenaria, is a commercially important bivalve with wide latitudinal distribution in North America. Populations of clams with a history
of repeated exposure to toxic Alexandrium spp. have developed a natural resistance to the paralytic shellfish toxins (PSTs) produced by these algae. An association
between PST resistance in individual clams and a single mutation in the saxitoxin (STX) binding region of the α-subunit of
the voltage-gated sodium (Na+) channel gene was previously identified. Here we establish that more than one mutation associated with nerve resistance to
STX occurred at this locus. Both cDNA from mRNA and genomic DNA sequences from individual clams are identical demonstrating
that both alleles are expressed simultaneously. In addition, one resistant allele per individual is sufficient to confer neural
resistance to STX even though heterozygous individuals show an intermediate level of resistance to STX in in vitro nerve trunk
assays. 相似文献
248.
This paper describes a novel analytical methodology using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to measure the 13C/12C ratios of chloroacetic acids (CAAs). CAAs are a major class of environmental pollutants that are widely distributed throughout the world, often at relatively high concentrations, and are of concern due to their toxic effects, particularly on plants. The 13C/12C of CAA reagents was measured by IRMS subsequent to offline combustion. Aqueous solutions of these CAAs were derivatized to the corresponding methyl chloroacetates (MCAAs) with acidic methanol with a known isotopic composition, extracted into pentane, and analyzed by GC/C/IRMS. Measured 13C/12C ratios of derivatized MCAAs were in agreement with calculated values within 1 per thousand for monochloroacetic acid and trichloroacetic acid and within 2 per thousand for dichloroacetic acid, suggesting that methylation and other analytical methodology steps do not isotopically fractionate derivatized MCAAs. 13C/12C ratios of reagent CAAs from different sources had varying isotopic signatures suggesting differences in source carbon and/or production methods. Our results underscore the potential of stable isotopes to serve as tracers of environmental sources of CAAs. 相似文献
249.
Exposure efficiency: an idea whose time has come? 总被引:1,自引:0,他引:1
250.
Scott NA Tate KR Giltrap DJ Tattersall Smith C Wilde RH Newsome PF Davis MR 《Environmental pollution (Barking, Essex : 1987)》2002,116(Z1):S167-S186
We designed a soil carbon monitoring system for New Zealand using country-specific land use and soil carbon information. The system pre-stratifies the country by soil type, climate, and land use. Soils were placed in six IPCC soil categories; Podzols were added as they are widespread throughout New Zealand. Temperature was stratified into two categories, each spanning 7 degrees C. Moisture categories were based on water balance, and included five categories. Temperature and moisture stratification was based on the USDA Soil Classification system. Land use (10 categories) was based on 1980s survey data. Overall, 39 combinations of these three factors (cells) described 93% of the New Zealand landscape. Geo-referenced soil carbon data (carbon concentration and bulk density) were used to quantify average soil carbon for each of the 39 cells. Aggregating the polygons gave an estimated 1990 soil carbon baseline of 1152+/-44, 1439+/-73, and 1602+/-167 Mt C (mean+/-S.D.) for the 0-0.1, 0.1-0.3, and 0.3-1.0 m depth increments (not including forest floor carbon). The system described could also be used to quantify equilibrium changes in soil C associated with land-use change if land use is updated periodically. 相似文献