斜坡区和隆起区断裂密集带差异性及其对油气分布的控制作用

此文以霸县凹陷文安斜坡和饶阳凹陷留楚构造为研究对象,对比了斜坡区和隆起区断裂密集带的特征及其对不同构造部位油气分布的控制作用。在三维地震资料、钻井资料和已发现油气藏特征的基础上,利用断裂密集带识别方法和分类方案,识别出文安斜坡和留楚构造的断裂密集带,并对其进行了分类。对比两种构造部位断裂密集带发育的差异性及对油气分布的控制作用,认为隆起区(留楚构造)相对于斜坡区(文安斜坡)断裂密集带发育数量较少,规模大,斜坡区断裂密集带主要以顺向背形断裂密集带为主,而隆起区主要以屋脊背形断裂密集带为主,隆起区油气主要分布在顺向背形断裂密集带内,斜坡区主要分布在屋脊背形断裂密集带内部及靠近生烃中心的边部。     

Effect of chronic exposure to cadmium on hepatic drug metabolism

Abstract

In an attempt to examine the chronic effect of low levels of cadmium on hepatic drug‐metabolizing enzyme system, an experiment was carried out in which growing male rats were given 0, 5, 10, and 2 0 ppm of cadmium in drinking water for a period of 8 weeks. An ip administration of a hypnotic dose of pentobarbital to the cadmium‐treated and the control rats 2 4 hr following the termination of the experiment exhibited that there was no significant difference in the drug metabolism in control and any of the treated groups. Next, liver microsomes were isolated from animals in all groups to study their ability to metabolize drugs in vitro. The results indicated that the activity of benzphetamine N‐demethylase and aniline hydroxylase, and the concentration of microsomal cytochrome P‐450 were almost identical in the control and treated groups. On the other hand, a single ip dose of cadmium (2 mg/kg) caused significant decrease in the in vivo and in vitro microsomal drug metabolism. These results suggest that although a single ip dose of cadmium (2 mg/kg) causes significant inhibition of drug metabolism, chronic exposure to cadmium up to 2 0 ppm in drinking water over a period of 8 weeks is unlikely to affect hepatic drug metabolism.     

Trophic ecology of coral reef gobies: interspecific,ontogenetic, and seasonal comparison of diet and feeding intensity

In fishes, a small body size may facilitate cost-effective exploitation of various primary and secondary food resources, but may pose difficulties associated with digestion of plant material and finding sufficient food in a foraging area potentially restricted by a high risk of predation. We examined the trophic ecology of five common, small-bodied coral reef fish from the family Gobiidae. For each species, we determined diet composition, feeding bite rate, foraging substrate, and feeding behaviour, and examined whether diet composition and feeding bite rate changed ontogenetically and seasonally. The five species showed a diverse range of trophic modes: Amblygobius bynoensis and Amblygobius phalaena were herbivores, Valenciennea muralis was a carnivore, Asterropteryx semipunctatus a detritivore, and Istigobius goldmanni an omnivore. Both the herbivores and detritivore supplemented their diet with animal material. The consumption of a wide range of dietary resources by the two smallest species with the most restricted mobility (A. semipunctatus and I. goldmanni) may ensure energy requirements are met within a restricted foraging area. There was a significant difference in mean feeding bite rate among species, with carnivore > herbivore > omnivore > detritivore. None of the species exhibited an ontogenetic shift in diet composition or increase in feeding bite rate, indicating that (1) postmaturation growth is not facilitated by a higher quality diet or increased feeding intensity following maturation, and (2) their small body size does not preclude herbivory. The herbivores had the highest gut:fish length ratio, which may facilitate plant digestion. While diet did not change seasonally, the mean feeding bite rate was significantly lower in winter than summer for four of the study species.     

Diamondback Terrapin (Malaclemys terrapin) Mortality in Crab Pots

The entrapment of diamondback terrapins (  Malaclemys terrapin) in crab pots frequently results in drowning and death of the trapped turtles. We determined the rate of capture, size, sex, and age of terrapins captured, and the potential impact crab pot mortality has on local terrapin populations. We estimated terrapin capture rates of 0.17 terrapins/pot/day in shallow water areas of Chesapeake Bay (Maryland, USA). The sex ratio of terrapins caught in crab pots was 3:2 male biased because female terrapins become too large to enter crab pots by the time they reach 8 years of age. Males, however, remain vulnerable to entrapment throughout their life. Our estimates of capture rates and local population size suggest that 15–78% of a local population may be captured in a single year. As a consequence, crab pots may be the major reason terrapins are extirpated in coastal, shallow water areas with heavy crab pot fisheries. Additionally, the selective removal of males may also contribute to female-biased sex ratios observed in this diamondback terrapin population. We developed and tested a modified crab pot that increases terrapin survival and does not reduce the number of crabs caught. Our modified crab pot maintained permanent access to air and prevented the drowning of terrapins. Additionally, our modified crab pot caught more crabs than standard commercial crab pots, suggesting that the modified crab pot could be a viable alternative to standard traps that result in terrapin mortality.     

Socioecological influences on the reproductive success of female mountain gorillas (<Emphasis Type="Italic">Gorilla beringei beringei</Emphasis>)

Over the past few decades, socioecological models have been developed to explain the relationships between the ecological conditions, social systems, and reproductive success of primates. Feeding competition, predation pressures, and risk of infanticide are predicted to influence how female reproductive success (FRS) depends upon their dominance rank, group size, and mate choices. This paper examines how those factors affected the reproductive success of female mountain gorillas (Gorilla beringei beringei) of the Virunga Volcanoes, Rwanda from 1967–2004. Reproductive success was measured through analyses of interbirth intervals, infant survival, and surviving infant birth rates using data from 214 infants born to 67 females. Mountain gorillas were predicted to have “within-group scramble” feeding competition, but we found no evidence of lower FRS in larger groups, even as those groups became two to five times larger than the population average. The gorillas are considered to have negligible “within-group contest” competition, yet higher ranked mothers had shorter interbirth intervals. Infant survival was higher in multimale groups, which was expected because infanticide occurs when the male dies in a one-male group. The combination of those results led to higher surviving birth rates for higher ranking females in multimale groups. Overall, however, the socioecological factors accounted for a relatively small portion of the variance in FRS, as expected for a species that feeds on abundant, evenly distributed foliage.     

Watershed surveys to support an assessment of the regional effects of acidic deposition on surface water chemistry

Through the Direct/Delayed Response Project (DDRP), the United States Environmental Protection Agency is attempting to assess the risk to surface waters from acidic deposition in three regions of the eastern United States: the Northeast Region, the Southern Blue Ridge Province, and the Mid-Appalachian Region. The central policy question being addressed by the DDRP is: Within the regions of concern, how many surface water systems (lakes, streams) will become acidic due to current or altered levels of acidic sulfur deposition, and on what time scales? The approach taken by the DDRP is to select a statistically representative set of watersheds in each region of concern and to project the future response of each watershed to various assumed levels of acidic deposition. The probability structure will then be used to extrapolate the watershed-specific results to each region. The data will be used also for statistical investigation of hypothesized relationships between current surface water chemistry and watershed characteristics. Because the needed terrestrial data base was not available, regional watershed surveys were conducted to meet the specific data needs of the DDRP. Maps (1∶24,000) of soils, vegetation, land use, depth to bedrock, and bedrock geology were made for each watershed. The soils were grouped into sampling classes based on their hypothesized response to acidic deposition. Randomized sampling of these classes provided regional means and variances of soil properties that can be applied to individual watersheds. Because of DDRP's need for consistency within and among regions, unique quality control/quality assurance activities were developed and implemented. After verification and validation, the DDRP data base will be made publicly available. This will be a unique and useful resource for others investigating watershed relationships on a regional scale. The results of these surveys and the conclusions of the DDRP will be presented in several future papers. The current paper gives an overview of the context, rationale, logistical considerations, and implementation of these surveys, with special emphasis on the field activities of watershed mapping and soil sampling. This discussion should be useful to those planning, implementing, and managing survey activities in support of regional assessments of other environmental concerns, who are likely to face similar choices and constraints.     

Fitness consequences of dispersal decisions for male mountain gorillas (Gorilla beringei beringei)

The fitness consequences of dispersal decisions are difficult to quantify, especially for long-lived species with complex social systems. To calculate those consequences for male mountain gorillas, from the perspective of both subordinate and dominant males, we used behavioral and demographic data obtained over 30 years from the Virunga Volcano population to develop an agent-based model that simulates the life history events, social structure, and population dynamics of the species. The model included variables for birth rates, mortality rates, dispersal patterns, and reproductive skew. The model predicted an average lifetime reproductive success (LRS) of 3.2 for philopatric males (followers) and 1.6 for emigrants. The benefits of philopatry were most sensitive to opportunities for social queuing and to female transfer preferences, but philopatry remained the best strategy over a wide range of group conditions and hypothetical simulations. The average LRS for dominant males was 4.5 when a subordinate stayed and 4.6 when the subordinate emigrated. The dispersal decision of the subordinate male had little impact on the fitness of the dominant male because it came relatively late in the dominant males reproductive life span, and it changed his group composition only incrementally. The fitness consequences for the dominant male were most sensitive to the degree of reproductive skew. Since subordinates suffer a fitness loss when they leave a group, they should accept whatever reproductive restraint is needed to avoid eviction, and the dominant male does not need to offer concessions for them to stay. The dominant male may offer reproductive concessions for other reasons, such as peace incentives or to confuse paternity, or he may not have complete control of reproduction within his group.Communicated by D. Watts     

Late Paleozoic gabbroic rocks of the Bridge River accretionary complex, southwestern British Columbia: geology and geochemistry

Gabbroic bodies in the Bralorne-Gold Bridge area of southwestern British Columbia are associated with the oceanic Bridge River complex of the western Canadian Cordillera, one of the suspect terranes accreted to North America in the Jurassic. The gabbros are locally cut by tonalites and are structurally interleaved with ultramafic rocks, phyllites, graphitic cherts, and carbonate lenses that comprise the lower part of the Bridge River complex. Their late Carboniferous crystallization age overlaps the depositional age of affiliated supracrustal rocks (Mississippian-Jurassic), some of which have been metamorphosed to blueschist facies. Compositionally, the gabbros resemble mafic plutonic rocks of ophiolitic complexes and gabbroic rocks of the nearby Shulaps Range. They display some affinity to oceanic island arc tholeiitic suites. The Bralorne and Shulaps gabbros include cumulates and appear to have been derived from a single, light REE-depleted, peridotitic source by melting and subsequent fractional crystallization/accumulation of various combinations of plagioclase, pyroxenes, and olivine. The tonalites are compositionally distinct from typical ophiolitic plagiogranites, but might be related to the associated gabbros. The gabbroic bodies occur within tectonic slivers derived from the oceanic crust that floored a deep ocean basin that existed during the late Paleozoic and early Mesozoic. The Bridge River complex comprises fragments of oceanic crust that were tectonically incorporated into an east-verging accretionary prism during a middle/late Triassic to Jurassic collisional event.     

Green abalone, <Emphasis Type="Italic">Haliotis fulgens</Emphasis> infected with the agent of withering syndrome do not express disease signs under a temperature regime permissive for red abalone, <Emphasis Type="Italic">Haliotis rufescens</Emphasis>

All California abalone species have been shown to be susceptible to infection with the bacterial agent of abalone withering syndrome (WS), although expression of signs of the disease may vary between species and with environmental conditions. We examined thermal modulation of WS expression in green abalone Haliotis fulgens at temperatures mimicking El Niño (18.0°C) and La Niña (14.2°C) events in southern California. In contrast to results obtained from previous experiments with red abalone, H. rufescens, the higher temperature did not result in higher infection intensities of the causative agent of the disease nor increase in clinical signs of disease. These results demonstrate clear differences in thermal regulation of disease expression between abalone species, and provide further data suggesting that green abalone should be a target species of recovery efforts in southern California, where WS is endemic.     

Iteroparity in the variable environment of the salamander Ambystoma tigrinum

Simultaneous estimation of survival, reproduction, and movement is essential to understanding how species maximize lifetime reproduction in environments that vary across space and time. We conducted a four-year, capture-recapture study of three populations of eastern tiger salamanders (Ambystoma tigrinum tigrinum) and used multistate mark-recapture statistical methods to estimate the manner in which movement, survival, and breeding probabilities vary under different environmental conditions across years and among populations and habitats. We inferred how individuals may mitigate risks of mortality and reproductive failure by deferring breeding or by moving among populations. Movement probabilities among populations were extremely low despite high spatiotemporal variation in reproductive success and survival, suggesting possible costs to movements among breeding ponds. Breeding probabilities varied between wet and dry years and according to whether or not breeding was attempted in the previous year. Estimates of survival in the nonbreeding, forest habitat varied among populations but were consistent across time. Survival in breeding ponds was generally high in years with average or high precipitation, except for males in an especially ephemeral pond. A drought year incurred severe survival costs in all ponds to animals that attempted breeding. Female salamanders appear to defer these episodic survival costs of breeding by choosing not to breed in years when the risk of adult mortality is high. Using stochastic simulations of survival and breeding under historical climate conditions, we found that an interaction between breeding probabilities and mortality limits the probability of multiple breeding attempts differently between the sexes and among populations.