Effects of multiple perturbations on the survivorship of fragments of three coral species     

Dizon RM  Yap HT 《Marine pollution bulletin》2006,52(8):928-934

Fist-sized fragments of Porites cylindrica, Porites rus and Pavona frondifera were deployed in single-species (P. cylindrica) and mixed-species (all three) plots in a shallow reef area in the northwestern Philippines. After 6 months, the corals in half of the plots were broken into smaller pieces to simulate an episodic physical disturbance. The survival of all corals was monitored from March 2000 to July 2001 during which the corals experienced 2 typhoons and episodes of algal overgrowth. For both intact and broken treatments, there was significantly higher survival in the mixed-species plots than in the single-species treatments. Fragment mortality varied between disturbances of varying frequencies and magnitudes, namely: one-time fragmentation stress, seasonal overgrowth by cyanobacteria and macroalgae, short-term (1 day) and long-term (more than 1 week) burial. The mixed-species assemblages had higher fragment survivorship than the monospecific assemblages during small-scale perturbations (e.g., algal overgrowth), but not in the face of subsequent, larger scale disturbances. This study emphasizes that coral responses to disturbance are both species- and context-specific.  相似文献   

Microbial community of cyanobacteria mats in the intertidal zone of oil-polluted coast of Saudi Arabia     

Al-Thukair AA  Abed RM  Mohamed L 《Marine pollution bulletin》2007,54(2):173-179

Cyanobacterial mats are found at various locations along the coast of the Eastern Province of Saudi Arabia. Those mats were affected by severe oil pollution following 1991 oil spill. In this study, samples from Abu Ali Island were collected at three selected sampling sites across the intertidal zone (Lower, Middle, and Upper) in order to understand the effect of extreme environmental conditions of high salinity, temperature and desiccation on distribution of cyanobacteria along the oil polluted intertidal zone. Our investigation of composition of cyanobacteria and diatoms was carried out using light microscopy, and Denaturant Gradient Gel Electrophoresis (DGGE) technique. Light microscopy identification revealed dominant cyanobacteria to be affiliated with genera Phormidium, Microcoleus, and Schizothrix, and to a lesser extent with Oscillatoria, Halothece, and various diatom species. The analysis of DGGE of PCR-amplified 16S rRNA fragments showed that the diversity of cyanobacteria decreases as we proceed from the lower to the upper intertidal zone. Accordingly, the tidal regime, salinity, elevated ambient air temperature, and desiccation periods have a great influence on the distribution of cyanobacterial community in the oil polluted intertidal zone of Abu Ali Island.  相似文献   

Structure of microbial communities and hydrocarbon-dependent sulfate reduction in the anoxic layer of a polluted microbial mat     

Abed RM  Musat N  Musat F  Mussmann M 《Marine pollution bulletin》2011,62(3):539-546

The bacterial communities in the anoxic layer of a heavily polluted microbial mat and their growth on hydrocarbons under sulfate-reducing conditions were investigated. Microbial communities were dominated by members of Alphaproteobacteria (27% of the total rRNA), Planctomycetes (21.1%) and sulfate-reducing bacteria (SRB: 17.5%). 16S rRNA cloning revealed sequences beloning to the same bacterial groups with SRB affiliated to the genera Desulfobulbus, Desulfocapsa, Desulfomicrobium, Desulfobacterium and Desulfosarcina/Desulfococcus. The derived enrichment cultures on crude oil, hexadecane and toluene were dominated by SRB. While most SRB sequences of the toluene and hexadecane cultures were related to the sequence of Desulfotignum toluolica, the crude oil enrichment showed a more diverse bacterial community with sequences from the genera Desulfotignum, Desulfobacter, Desulfatibacillus, Desulfosalina, and Desulfococcus. We conclude that the anoxic layer of the studied mats contains a diverse community of anaerobic bacteria, dominated by SRB, some of which are able to grow on hydrocarbons.  相似文献   

水平井重力泄油     

Butl.  RM 刘建华 《国外石油地质》1992,(3):67-79

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与金矿化共生的有机质的硫化作用多米尼加Pueblo Viejo矿区实例     

Kett.  RM 胡明安 《地质科学译丛》1991,8(3):68-74

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气候变化对共水系统可靠性,回弹性,脆弱性影响的区域评价     

Vogel  RM 李中平 《水文科技信息》1997,14(A00):42-58

研究气候变化对水资源系统的影响通常是建立详细的月水文、气候和水库运行模型来对特定的供水系统进行模拟。这些研究结果只适用于被研究的供水系统。本文旨在建立一个区域水文气候评价模型，并研究该模型所带来的巨大潜力。这样的模型适用于在更大的地理范围内确定气候变化对供水特性的影响情况。  相似文献   

Deeply Penetrating Banded Zonal Flows in the Solar Convection Zone     

Howe R  Christensen-Dalsgaard J  Hill F  Komm RW  Larsen RM  Schou J  Thompson MJ  Toomre J 《The Astrophysical journal》2000,534(2):L163-L166

We discuss the spectrum arising from synchrotron emission by fast cooling (FC) electrons, when fresh electrons are continually accelerated by a strong blast wave, into a power-law distribution of energies. The FC spectrum has so far been described by four power-law segments divided by three break frequencies nusa相似文献   

煤层甲烷：从灾害到资源     

Flor.  RM 张笑薇 《国外煤田地质》1999,(1):1-9

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Nematode community dynamics over an annual production cycle in the central North Sea     

Schratzberger M  Forster RM  Goodsir F  Jennings S 《Marine environmental research》2008,66(5):508-519

Nematode species composition, trophic structure and body size distributions were followed over an annual production cycle in the central North Sea; to test responses to temporally changing food quality and quantity in the sediment. Changes in the phytoplankton concentration in the water column were quantitatively reflected in the concentration of chlorophyll a and breakdown products in the sediment, with higher concentrations in spring and autumn following blooms, and lower concentrations in summer and winter. The taxonomic and trophic structure of nematode communities differed significantly among stations over relatively short distances, potentially masking some of the temporal dynamics. Spatio-temporal differences in nematode species composition were linked to changes in the quality and quantity of organic material reaching the seabed, reflecting a species-specific response to the nutritional quality of sedimenting organic material and the biochemical changes in the sediment associated with its decomposition. The size distributions of selected nematode species indicated that most species bred continuously throughout the sampling period, although one species, the epigrowth feeder Spilophorella paradoxa, had periods of increased growth following the deposition of the spring phytoplankton bloom. There was no consistent temporal relationship between the trophic composition of nematode communities and spring chlorophyll a or carbon sedimentation, most likely a result of the trophic plasticity of most feeding types and the capacity of the community to use both freshly sedimented material as well as the subsequent breakdown products and refractory organic matter. Community metrics implied that there were small responses to the seasonal production cycle, but these belied strong responses of a few species with life histories that allowed them to track the availability of suitable food resources.  相似文献   

Estuarine fish health assessment: evidence of wastewater impacts based on nitrogen isotopes and histopathology   总被引：2，自引：1，他引：1  

Schlacher TA  Mondon JA  Connolly RM 《Marine pollution bulletin》2007,54(11):1762-1776

Sewage effluent is a powerful agent of ecological change in estuaries. While the effects of sewage pollution on water quality are usually well documented, biological responses of exposed organisms are not. We quantified health impacts in the form of pathological tissue changes across multiple organs in estuarine fish exposed to elevated levels of treated wastewater. Structural pathologies were compared in wild populations of four fish species from two subtropical estuaries on the east coast of Australia that differ substantially in the amount of direct wastewater loadings. Uptake of sewage-derived nitrogen by fish was traced with stable nitrogen isotopes. Pathologies were common in the liver, spleen, gill, kidney and muscle tissues, and included granulomas, melanomacrophage aggregates, and multiple deformities of the gill epithelia. Tissue deformities were more frequent in fish exposed directly to wastewater discharges. Mullet (Valamugil georgii) were most affected, with only a single specimen free of pathologies in the sewage-impacted estuary. Similarly, in those fish that had structural abnormalities, more deformities were generally found in individuals from sites receiving sewage. These spatial contrasts in impaired fish health correspond to significantly enriched delta15N values in fish muscle as a consequence of fish assimilating sewage-N. Overall, the pattern of lower health and enriched delta15N values in fish from sewage-impacted areas suggests that organism health is lowered by sewage inputs to estuaries. Measurements of organism health are required to understand the effects of sewage on estuarine ecosystems, and histopathology of fishes is a powerful tool to achieve this.  相似文献