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31.
32.
Assessment of the Water Quality and Ecosystem Health of the Great Barrier Reef (Australia): Conceptual Models 总被引:3,自引:0,他引:3
Haynes D Brodie J Waterhouse J Bainbridge Z Bass D Hart B 《Environmental management》2007,40(6):993-1003
Run-off containing increased concentrations of sediment, nutrients, and pesticides from land-based anthropogenic activities
is a significant influence on water quality and the ecologic conditions of nearshore areas of the Great Barrier Reef World
Heritage Area, Australia. The potential and actual impacts of increased pollutant concentrations range from bioaccumulation
of contaminants and decreased photosynthetic capacity to major shifts in community structure and health of mangrove, coral
reef, and seagrass ecosystems. A detailed conceptual model underpins and illustrates the links between the main anthropogenic
pressures or threats (dry-land cattle grazing and intensive sugar cane cropping) and the production of key contaminants or
stressors of Great Barrier Reef water quality. The conceptual model also includes longer-term threats to Great Barrier Reef
water quality and ecosystem health, such as global climate change, that will potentially confound direct model interrelationships.
The model recognises that system-specific attributes, such as monsoonal wind direction, rainfall intensity, and flood plume
residence times, will act as system filters to modify the effects of any water-quality system stressor. The model also summarises
key ecosystem responses in ecosystem health that can be monitored through indicators at catchment, riverine, and marine scales.
Selected indicators include riverine and marine water quality, inshore coral reef and seagrass status, and biota pollutant
burdens. These indicators have been adopted as components of a long-term monitoring program to enable assessment of the effectiveness
of change in catchment-management practices in improving Great Barrier Reef (and adjacent catchment) water quality under the
Queensland and Australian Governments’ Reef Water Quality Protection Plan. 相似文献
33.
Yan Jiang Jane R. Frankenberger Yinghui Sui Laura C. Bowling 《Journal of the American Water Resources Association》2014,50(6):1501-1514
Subsurface tile‐drained agricultural fields are known to be important contributors to nitrate in surface water in the Midwest, but the effect of these fields on nitrate at the watershed scale is difficult to quantify. Data for 25 watersheds monitored by the Indiana Department of Environmental Management and located near a U.S. Geological Survey stream gage were used to investigate the relationship between flow‐weighted mean concentration (FWMC) of nitrate‐N and the subsurface tile‐drained area (DA) of the watershed. The tile DA was estimated from soil drainage class, land use, and slope. Nitrate loads from point sources were estimated based on reported flows of major permitted facilities with mean nitrate‐N concentrations from published sources. Linear regression models exhibited a statistically significant relationship between annual/monthly nonpoint source (NPS) nitrate‐N and DA percentage. The annual model explained 71% of the variation in FWMC of nitrate‐N. The annual and monthly models were tested in 10 additional watersheds, most with absolute errors within 1 mg/l in the predicted FWMC. These models can be used to estimate NPS nitrate for unmonitored watersheds in similar areas, especially for drained agricultural areas where model performance was strongest, and to predict the nitrate reduction when various tile drainage management techniques are employed. 相似文献
34.
Ian C. Gilby Lauren J. N. Brent Emily E. Wroblewski Rebecca S. Rudicell Beatrice H. Hahn Jane Goodall Anne E. Pusey 《Behavioral ecology and sociobiology》2013,67(3):373-381
Coalitionary aggression occurs when at least two individuals jointly direct aggression at one or more conspecific targets. Scientists have long argued that this common form of cooperation has positive fitness consequences. Nevertheless, despite evidence that social bond strength (which is thought to promote coalition formation) is correlated with fitness in primates, cetaceans, and ungulates, few studies have directly examined whether coalitionary aggression improves reproductive success. We tested the hypothesis that among free-ranging chimpanzees (Pan troglodytes schweinfurthii), participation in coalitionary aggression increases reproductive output. Using 14 years of genetic and behavioral data from Gombe National Park, Tanzania, we found that coalitionary aggression increased a male’s chances of (A) siring offspring, compared to other males of similar dominance rank, and (B) ascending in rank, a correlate of future reproductive output. Because male chimpanzees form coalitions with many others within a complex network, we used social network analysis to identify the types of connections correlated with these fitness benefits. The beneficiaries of coalitionary aggression were males with the highest “betweenness”—that is, those who tended to have coalition partners who themselves did not form coalitions with each other. This suggests that beyond simply recognizing third-party relationships, chimpanzees may use this knowledge to choose coalition partners. If so, this is a significant step forward in our knowledge of the adaptive value of social intelligence. Regardless of mechanism, however, this is the first evidence of genetic benefits of coalitionary aggression in this species, and therefore has important implications for understanding the evolution of cooperation. 相似文献
35.
This paper introduces the problems of a market-driven waste management strategy in the UK and the momentum towards developing markets for recycled materials. It focuses on the demand side barriers and principally the need for market stimulation in the end uses for recyclables. The important role, which small- and medium-sized manufacturing enterprises (SMEs) have to play in developing existing markets for recyclate, is discussed. SMEs also have the potential to contribute to the radical new approach of identifying and developing a broad range of new, more diverse and higher value uses for recyclate. If these enterprises are to be engaged effectively then regional action is essential. The paper then reports on research work focusing on SMEs that has taken place as a component of the CWMRE (Creating Welsh Markets for REcyclate) market development initiative in Wales. As a foundation for this, a series of semi-structured interviews with SMEs has been conducted with those operating in sectors that are known to have the potential to provide novel applications for secondary materials or to have the potential for material displacement. Some of the barriers and corresponding needs within the case study companies involved are discussed. The implications of these findings for a regional market development programme are considered and in particular how these case studies support the need to engage SMEs in the use of secondary materials. 相似文献
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38.
Although it is understood that the composition of riparian trees can affect stream function through leaf litter fall, the potential effects of genetic variation within species are less understood. Using a naturally hybridizing cottonwood system, we examined the hypothesis that genetic differences among two parental species (Populus fremontii and P. angustifolia) and two groups of their hybrids (F1 and backcrosses to P. angustifolia) would affect litter decomposition rates and the composition of the aquatic invertebrate community that colonizes leaves. Three major findings emerged: (1) parental and hybrid types differ in litter quality, (2) decomposition differs between two groups, a fast group (P. fremontii and F1 hybrid), and a slow group (P. angustifolia and backcross hybrids), and (3) aquatic invertebrate communities colonizing P. fremontii litter differed significantly in composition from all other cross types, even though P. fremontii and the F1 hybrid decomposed at similar rates. These findings are in agreement with terrestrial arthropod studies in the same cottonwood system. However, the effects are less pronounced aquatically than those observed in the adjacent terrestrial community, which supports a genetic diffusion hypothesis. Importantly, these findings argue that genetic interactions link terrestrial and aquatic communities and may have significant evolutionary and conservation implications. 相似文献
39.
Bumblebees can avoid recently depleted flowers by responding to repellent scent-marks deposited on flower corollas by previous visitors. It has previously been suggested that avoidance of visited flowers for a fixed period would be a poor strategy, since different plant species vary greatly in the rate at which they replenish floral rewards. In this study, we examined the duration of flower repellency after an initial bumblebee visit, using wild bumblebees (Bombus lapidarius, B. pascuorum and B. terrestris) foraging on four different plant species (Lotus corniculatus, Melilotus officinalis, Phacelia tanacetifolia and Symphytum officinale). We constructed a model to predict flower visitation following an initial visit, based on the nectar secretion pattern of the different plant species, the insect visitation rate per flower, and the search and handling times of bumblebees foraging on the plant species in question. The model predicts an optimal duration of flower avoidance which maximises the rate of reward acquisition for all bees. However, this optimum may be open to cheating. For two plant species, the evolutionary stable strategy (ESS) is a shorter duration of flower avoidance than the optimum. We found the duration of flower avoidance was markedly different among flower species and was inversely related to nectar secretion rates. The predicted ESSs for each plant species were close to those observed, suggesting that the key parameters influencing bumblebee behaviour are those included in the model. We discuss how bees may alter the duration of their response to repellent scents, and other factors that affect flower re-visitation. 相似文献
40.
Summary Werren and Charnov (1978) and Seger (1983) proposed a model to explain a fairly common pattern of alternating sex ratio biases between generations in partially bivoltine insects. When first-generation males overlap and mate with females of the second generation, then females should bias sex ratios in favor of sons for the first generation and daughters for the second generation. In an intensive, 7-year study at four sites in northern Florida, pipe-organ mud-daubing wasps (Trypoxylon (Trypargilum) politum; Hymenoptera: Sphecidae) were found to have strongly male-biased sex ratios in the first or overwintering generation and 1:1 or female-biased sex ratios in the second or summer generation. These differences were not due to differences in mortality of the two sexes but rather resulted from changing female sex-allocation decisions. In some respects the mud dauber results fit Seger's model well: alternating sex ratios in partially bivoltine populations, first-generation males overlapping second-generation females and perhaps most convincingly, northern, univoltine populations do not have a male bias. Despite this qualitative fit, however, our data do not meet the quantitative predictions of the model. This could result from the fact that some assumptions of the model are not met by the life history of T. politum. Alternative explanations for alternating sex ratios include split sex ratios, seasonal differences in cost ratios, facultative maternal investment rules and facultative overwintering decisions by offspring. Despite the position that sex ratios have achieved in the modern study of evolution, it is clear that accurate, quantitative predictions on sex-allocation patterns demand the same detailed understanding of the biology of the organism that is required for the study of other adaptations. 相似文献