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751.
We studied the relative roles of environmental species sorting and priority effects in the assembly of ecological communities on long time scales, by analyzing community turnover of water fleas (Daphnia) in response to strong and recurrent environmental change in a fluctuating tropical lake. During the past 1800 years, Lake Naivasha (Kenya) repeatedly fluctuated between a small saline pond habitat during lowstands and a large freshwater lake habitat during highstands. Starting from a paleoecological reconstruction, we estimated the role of priority effects in Daphnia community assembly across 16 of these habitat turnovers and compared this with the response of the community to reconstructed changes in three environmental variables important for species sorting. Our results indicate that the best predictor of Daphnia community composition during highstands was the community composition just prior to the transition from lowstands to highstands. This reflects a long-lasting priority effect of late lowstand communities on highstand communities, arising when remnant lowstand populations fill newly available ecological space in the rapidly expanding lake habitat. Species sorting and priority effects had a comparable but relatively small influence on community composition during the lowstands. Moreover, these priority effects decayed rapidly with time as Daphnia communities responded to environmental change, in contrast with the highstand communities where priority effects lasted for several decades. 相似文献
752.
Seasonal migration occurs in many animal systems and is likely to influence interactions between animals and their parasites. Here, we focus on monarch butterflies (Danaus plexippus) and a protozoan parasite (Ophryocystis elektroscirrha) to investigate how host migration affects infectious disease processes. Previous work showed that parasite prevalence was lower among migratory than nonmigratory monarch populations; two explanations for this pattern are that (1) migration allows animals to periodically escape contaminated habitats (i.e., migratory escape), and (2) long-distance migration weeds out infected animals (i.e., migratory culling). We combined field-sampling and analysis of citizen science data to examine spatiotemporal trends of parasite prevalence and evaluate evidence for these two mechanisms. Analysis of within-breeding-season variation in eastern North America showed that parasite prevalence increased from early to late in the breeding season, consistent with the hypothesis of migratory escape. Prevalence was also positively related to monarch breeding activity, as indexed by larval density. Among adult monarchs captured at different points along the east coast fall migratory flyway, parasite prevalence declined as monarchs progressed southward, consistent with the hypothesis of migratory culling. Parasite prevalence was also lower among monarchs sampled at two overwintering sites in Mexico than among monarchs sampled during the summer breeding period. Collectively, these results indicate that seasonal migration can affect parasite transmission in wild animal populations, with implications for predicting disease risks for species with threatened migrations. 相似文献
753.
The coexistence of four cryptic species of Rhabditis (Pellioditis) marina (Nematoda: Rhabditidae) at small geographical scale challenges ecological competition theory and was therefore studied in
the laboratory at two different salinities, where their performance in combined cultures was compared with that in monospecies
cultures. We found that three of the four cryptic species were able to coexist, but that interspecific interactions (competition
and facilitation) were common. Salinity had an effect on these interactions, with a shift from contest to scramble competition.
This shift may result from an increased population development of two of the four species at the lower salinity in the monospecific
cultures. This experiment demonstrates that abiotic conditions may play an important role in achieving coexistence between
cryptic species and can alter the interspecific interactions between them. 相似文献
754.
Worldwide blooms of the green alga Trichosolen have been reported on damaged coral reefs following catastrophic events. However, the global distribution of Trichosolen and the factors triggering such blooms remained elusive because of a paucity of occurrence records. This study presents a
presence-only niche modelling approach to map the potential distribution and delineate bloom risk areas as well as to identify
environmental response optima for non-blooming occurrences and blooms. The modelled suitability map revealed a pantropical
to subtropical distribution, while high suitability values delineated bloom risk areas including important tropical reef systems
where Trichosolen has not yet been reported from. While both blooms and non-bloom occurrences show a strong preference for high temperatures,
blooms responded better to broader nutrient ranges than non-blooms, suggesting the importance of sudden nutrient inputs during
catastrophic events in the formation of blooms. 相似文献
755.
756.
Le Trinh Hai Pham Hoang Hai Chu Lam Thai Jean Hugé Albert Ahenkan Le Xuan Quynh Vu Van Hieu Nguyen Le The Tung Luc Hens 《Environmental Modeling and Assessment》2011,16(6):541-550
Sustainable development is a widespread concept. Indicator selection and sustainability assessment are basic methods to analyse
the sustainable development process. This study aims to develop a software application to select indicators and to allocate
weightings to the indicators and the sub-indexes, so that they can be listed in a sustainability assessment. The Visual Basic
software is used to develop a software package based on Delphi, analytic hierarchy, normalization and combination processes.
Software for sustainability assessment was developed. Thirty-five indicators are selected as a first step of which eight health
indicators and eight environmental ones and their sub-indexes are given weightings. The indicators are normalized. Sub-indexes
are combined into a composite sustainable development index. The model is validated showing the ‘main features’ of the sustainability
situation on health and environmental aspects in the Quang Tri province during the period 2000–2005. The results support the
decision-making process of the competent authorities. 相似文献
757.
Santos Arleto T. Valverde Bruno S. L. De Oliveira Classius Franco-Belussi Lilian 《Environmental science and pollution research international》2021,28(16):20072-20081
Environmental Science and Pollution Research - The aim of this study was to evaluate the genotoxic and morphological systemic effects of both an acute and a chronic exposure of bullfrog tadpoles to... 相似文献
758.
Medina-Mijangos Rubí De Andrés Andrés Guerrero-Garcia-Rojas Hilda Seguí-Amórtegui Luis 《Environmental science and pollution research international》2021,28(15):18807-18825
Environmental Science and Pollution Research - Countries face a serious problem due to the generation and management of higher volumes of waste. Large-scale production of waste has promoted the... 相似文献
759.
Antonino Fiorentino Giuliana De Luc Luigi Rizzo Giacomo Viccione Giusy Lofrano Maurizio Carotenuto 《环境科学学报(英文版)》2018,30(7):95-104
The fate of indigenous surface-water and wastewater antibiotic resistant bacteria in a mild slope stream simulated through a hydraulic channel was investigated in outdoor experiments.The effect of(i) natural(dark) decay,(ii) sunlight,(iii) cloudy cover,(iv) adsorption to the sediment,(v) hydraulic conditions,(vi) discharge of urban wastewater treatment plant(UWTP)effluent and(vii) bacterial species(presumptive Escherichia coli and enterococci) was evaluated.Half-life time(T1/2) of E. coli under sunlight was in the range 6.48–27.7 min(initial bacterial concentration of 10~5 CFU/mL) depending on hydraulic and sunlight conditions. E. coli inactivation was quite similar in sunny and cloudy day experiments in the early 2 hr, despite of the light intensity gradient was in the range of 15–59 W/m~2; but subsequently the inactivation rate decreased in the cloudy day experiment(T1/2= 23.0 min) compared to sunny day(T_(1/2)= 17.4 min). The adsorption of bacterial cells to the sediment(biofilm) increased in the first hour and then was quite stable for the remaining experimental time. Finally, when the discharge of an UWTP effluent in the stream was simulated, the proportion of indigenous antibiotic resistant E. coli and enterococci was found to increase as the exposure time increased, thus showing a higher resistance to solar inactivation compared to the respective total populations. 相似文献
760.