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91.
Jean-Christophe Gaillard Catherine C. Liamzon Jessica D. Villanueva 《Environmental Hazards》2013,12(4):257-270
Between 14 November and 4 December 2004, four successive tropical depressions and typhoons lashed the Eastern coast of Luzon in the Philippines. Heavy rainfall triggered massive landslides and devastating flash floods, which brought tremendous damage and killed more than 1600 people. Immediately after the disaster, there was a media and political consensus to incrimate ‘extraordinary’ natural phenomena and widespread deforestation as responsible for the catastrophe. We argue that the tragedy that befell the municipalities of General Nakar, Infanta and Real, among other devastated areas, is enmeshed in a deeper tangle of causal factors that are political, socio-economic and demographic in nature. These factors include unmanaged population growth, difficult access to land and resources, corruption within the government, and power of the elite. 相似文献
92.
93.
The Science of Nature - Many insects use chemical defence mechanisms to defend themselves against predators. However, defensive secretions are costly to produce and should thus only be used in... 相似文献
94.
Floyd Jessica R. Kwoba Emmah Mwangi Thumbi Okotto-Okotto Joseph Wanza Peggy Wardrop Nicola Yu Weiyu Wright Jim A. 《Environmental science and pollution research international》2022,29(23):34314-34324
Environmental Science and Pollution Research - Given the increasing evidence that domestic contact with livestock is a risk factor for child diarrhoea in low- and middle-income countries, there... 相似文献
95.
Courtney E. Moore Steven P. Loheide II Christopher S. Lowry Jessica D. Lundquist 《Journal of the American Water Resources Association》2014,50(4):1033-1050
Vegetation in subalpine meadows in the Sierra Nevada Mountains is particularly vulnerable to lowering of groundwater levels because wet meadow vegetation is reliant upon shallow groundwater during the dry summer growing season. These ecosystems are especially vulnerable to channel incision as meadow aquifers are hydrologically connected to tributaries, and many have not yet recovered from previous anthropogenic influences. While instream restoration projects have become a common approach, lack of postrestoration monitoring and communication often result in a trial‐and‐error approach. In this study we demonstrate that preimplementation modeling of possible instream restoration solutions, chosen to raise stream stage and subsequently groundwater levels, is a useful tool for evaluating and comparing potential channel modifications. Modeling allows us to identify strategic locations and specific methods. Results show additional sediment depth and roughness on tributaries along with introduced woody debris (simulated by high roughness) on the Tuolumne River are the most effective means of raising stream stage. Results demonstrate that restoration efforts are most efficient in tributary streams. Managers and planners can more efficiently direct resources while minimizing the potential for negative impacts or failed restoration projects by modeling the possible effects of multiple restoration scenarios before implementation. 相似文献
96.
Oxygen minimum zones (OMZs) are natural physical features of the world's oceans. They create steep physiochemical gradients in the water column, which most notably include a dramatic draw down in oxygen concentrations over small vertical distances (<100 m). Microbial communities within OMZs play central roles in ocean and global biogeochemical cycles, yet we still lack a fundamental understanding of how microbial biodiversity is distributed across OMZs. Here, we used metagenomic sequencing to investigate microbial diversity across a vertical gradient in the water column during three seasons in the Eastern Tropical South Pacific (ETSP) OMZ. Based on analysis of small subunit ribosomal RNA (SSU rRNA) gene fragments, we found that both taxonomic and phylogenetic diversity declined steeply along the transition from oxygen-rich surface water to the permanent OMZ. We observed similar declines in the diversity of protein-coding gene categories, suggesting a decrease in functional (trait) diversity with depth. Metrics of functional and trait dispersion indicated that microbial communities are phylogenetically and functionally more overdispersed in oxic waters, but clustered within the OMZ. These dispersion patterns suggest that community assembly drivers (e.g., competition, environmental filtering) vary strikingly across the oxygen gradient. To understand the generality of our findings, we compared OMZ results to two marine depth gradients in subtropical oligotrophic sites and found that the oligotrophic sites did not display similar patterns, likely reflecting unique features found in the OMZ. Finally, we discuss how our results may relate to niche theory, diversity-energy relationships and stress gradients. 相似文献
97.
Metson GS Hale RL Iwaniec DM Cook EM Corman JR Galletti CS Childers DL 《Ecological applications》2012,22(2):705-721
As urban environments dominate the landscape, we need to examine how limiting nutrients such as phosphorus (P) cycle in these novel ecosystems. Sustainable management of P resources is necessary to ensure global food security and to minimize freshwater pollution. We used a spatially explicit budget to quantify the pools and fluxes of P in the Greater Phoenix Area in Arizona, USA, using the boundaries of the Central Arizona-Phoenix Long-Term Ecological Research site. Inputs were dominated by direct imports of food and fertilizer for local agriculture, while most outputs were small, including water, crops, and material destined for recycling. Internally, fluxes were dominated by transfers of food and feed from local agriculture and the recycling of human and animal excretion. Spatial correction of P dynamics across the city showed that human density and associated infrastructure, especially asphalt, dominated the distribution of P pools across the landscape. Phosphorus fluxes were dominated by agricultural production, with agricultural soils accumulating P. Human features (infrastructure, technology, and waste management decisions) and biophysical characteristics (soil properties, water fluxes, and storage) mediated P dynamics in Phoenix. P cycling was most notably affected by water management practices that conserve and recycle water, preventing the loss of waterborne P from the ecosystem. P is not intentionally managed, and as a result, changes in land use and demographics, particularly increased urbanization and declining agriculture, may lead to increased losses of P from this system. We suggest that city managers should minimize cross-boundary fluxes of P to the city. Reduced P fluxes may be accomplished through more efficient recycling of waste, therefore decreasing dependence on external nonrenewable P resources and minimizing aquatic pollution. Our spatial approach and consideration of both pools and fluxes across a heterogeneous urban ecosystem increases the utility of nutrient budgets for city managers. Our budget explicitly links processes that affect P cycling across space with the management of other resources (e.g., water). A holistic management strategy that deliberately couples the management of P and other resources should be a priority for cities in achieving urban sustainability. 相似文献
98.
Pacific lion-paw scallops were collected from natural aggregations in Laguna Ojo de Liebre (Pacific Ocean), the Gulf of California,
and from aquaculture facilities for genetic diversity analyses. Mitochondrial DNA sequencing uncovered two highly supported
clades separated by 2.5% divergence. Data from ten microsatellite markers suggest individuals from these mitogroups are introgressed,
raising questions about the mitotype origin. Some evidence suggests gene flow between La Paz and Ojo de Liebre; otherwise
the Gulf of California and Ojo de Liebre are acting as two distinct populations. It is unclear whether translocations between
sites have influenced the observed genetic structure or whether gene flow has been facilitated by past geologic events. Finally,
scallops spawned for aquaculture are unique from the wild and have significantly less diversity. These results warrant the
attention of managers and producers who should work to monitor and conserve genetic diversity in both wild and aquaculture
populations. 相似文献
99.
Sitthipong Wongvilas Jessica S. Higgs Madeleine Beekman Wandee Wattanachaiyingcharoen Sureerat Deowanish Benjamin P. Oldroyd 《Behavioral ecology and sociobiology》2010,64(7):1165-1170
The dwarf honeybees Apis florea and Apis andreniformis are sympatric in Southeast Asia. We examined undisturbed nests of both species finding that heterospecific workers are present
in some nests at low frequency. This suggested that workers may enter heterospecific nests as a prelude to reproductive parasitism.
To test this hypothesis, we created mixed-species colonies and determined the reproductive response of workers within them
based on molecular markers. In queenless colonies, workers of both species activated their ovaries at equal frequency. However,
the majority species, A. florea, had complete reproductive dominance over A. andreniformis, most likely because the A. florea workers recognised and removed heterospecific larvae. In queenright mixed-species colonies, workers responded to heterospecific
signals of the presence of the queen and did not activate their ovaries. Thus, despite predictions from kin selection theory
that workers would benefit from parasitising heterospecific nests, we find no evidence that selection has established a parasitic
strategy in these sibling species. 相似文献
100.
The current range of ecological habitats occupied by a species reflects a combination of the ecological tolerance of the species, dispersal limitation, and competition. Whether the current distribution of a species accurately reflects its niche has important consequences for the role of ecological niche modeling in predicting changes in species ranges as the result of biological invasions and climate change. We employed a detailed data set of species occurrence and spatial variation in biotic and abiotic attributes to model the niche of a native California annual plant, Collinsia sparsiflora. We tested the robustness of our model for both the realized and fundamental niche by planting seeds collected from four populations, representing two ecotypes, into plots that fully represented the five-dimensional niche space described by our model. The model successfully predicted which habitats allowed for C. sparsiflora persistence, but only for one of the two source ecotypes. Our results show that substantial niche divergence has occurred in our sample of four study populations, illustrating the importance of adequately sampling and describing within-species variation in niche modeling. 相似文献