To determine whether the functional stability of nitrification was correlated to a stable community structure of ammonia oxidizing bacteria (AOB) in a full-scale wastewater treatment plant, the AOB community dynamics in a wastewater treatment system was monitored over one year. The community dynamics were investigated using specific PCR followed by terminal restriction fragment length polymorphism (T-RFLP) analysis of the amoA gene. The T-RFLP results indicated that during the period of nitrification stability, the AOB community structure in the full-scale wastewater treatment system was relatively stable, and the average change rate every 15 d of the system was 6.6%±5.8%. The phylogenetic analysis of the cloned amoA gene showed clearly that the dominant AOB in the system was Nitrosomonas spp. The results of this study indicated that throughout the study period, the AOB community structure was relatively stable in the full-scale wastewater treatment system with functional stability of nitrification. 相似文献
Microbial activity and accumulation of organic matter in the burrow of the thalassinidean mud shrimp, Upogebia major, were studied on a tidal flat along the northern coast of Tokyo Bay, Japan. The burrow of U. major is Y-shaped with an upper U-shaped part plus a lower I-shaped part. Its lower part can extend to a depth of 2 m. In the present
study, we compare electron transport system activity (ETSA), bacterial abundance and organic matter content [total organic
carbon (TOC), total nitrogen (TN) and chlorophyll a (chl. a)] of the burrow wall sediment with the tidal flat surface and non-burrow sediments. We also compared the U- and I-shaped
part in terms of these parameters. ETSA in the burrow wall was higher than at the tidal flat surface in the warmer season,
and was always higher than at surrounding non-burrow sediments. Bacterial abundance in the burrow wall was higher than at
the tidal flat surface and surrounding sediment. TOC and TN contents in the burrow wall were two to three times higher than
those at the tidal flat surface and non-burrow sediments, regardless of season. However, there was no significant difference
in chl. a content between burrow wall and tidal flat surface. These results suggest that organic enrichment of the burrow wall is a
result of organic matter particles such as phytodebris accumulation along the burrow wall. For all parameters of the burrow
walls, no statistical differences were found between the two parts. Present results indicate that U. major actively transports the water containing suspended organic particles not only through the U-part but also into the deeper
I-part. These indicate that burrow of the mud shrimp provides a dynamic environment for microbial community in tidal flat
sediment. 相似文献
Restriction fragment length polymorphism (RFLP) analysis was performed on PCR amplified DNA fragments containing the control
region of the swordfish (Xiphias gladius Linnaeus, 1758) mitochondrial DNA. A total of 456 individuals comprising 13 local samples (six Pacific, three Atlantic, the
Mediterranean Sea, two Indian Ocean and the Cape of Good Hope) were surveyed with four endonucleases (Alu I, Dde I, Hha I and Rsa I), yielding a total of 52 composite genotypes. Within-sample genotypic diversity (H) was high ranging from 0.702 to 0.962 with a value of 0.922 for the pooled sample. Significant geographic variation in the
frequencies of genotypes and restriction patterns was revealed. The Mediterranean sample was highly distinct from all other
samples. Further, Rsa I digestion revealed high levels of polymorphism in all but the Mediterranean samples, indicating that exogenous swordfishes
rarely enter that body of water. Heterogeneity between the North and South Atlantic samples was significant, both of which
differed from those of the Pacific. In contrast, the Indian Ocean samples were not significantly different from the samples
of South Atlantic and Pacific. Genetic differentiation among the Pacific samples was low. The results indicate that the world-wide
swordfish population is genetically structured not only among, but also within ocean basins and suggest that gene flow is
restricted despite the absence of geographic barriers.
Received: 28 August 1996 / Accepted: 2 October 1996 相似文献
Along a composite onshore-offshore gradient, 4 homogeneous areas within beds of the marine angiosperm Thalassia were studied in detail. Eleven environmental variables, and molluscan and echinoderm abundance were sampled at monthly intervals for 1 year. Environmental conditions were generally more extreme, and their variance greatest, nearshore; they decreased significantly with distance from shore. Environmental predictability and cumulative diversity (H) increased with distance from shore, whereas abundance was greatest in the higher-stress environments. Over the year, the population variance (number of species, density, and diversity) was no greater in the unpredictable, low diversity environments than in the more predictable, high-diversity environments. Bivalves collected from the low-diversity environments were markedly eurytopic forms. whereas the highest-diversity area contained predominantly stenotopic taxa. Typical suspension feeders were dominant only in the most diverse area, whereas more generalized feeders dominated the higher-stress environments. There was no correlation between bivalve diversity increased with the variety of available food. Evidence suggests that catastrophes and other long-term phenomena, and biological factors such as predation, are of great importance in determining the differences in fauna between these areas. 相似文献
Abstract The near shore coastal and marine environment of several Caribbean islands is their most biologically productive and economically important zone. However, almost all landbased activities possess the real potential of degrading the quality of near shore waters and ultimately diminishing the utility of the marine resource. This condition is largely attributed to the individual smallness of the islands and their geographic proximity to each other. Available sanitary water quality data from across the region indicated that while recreational areas are in general safe for water contact activities, bacterial densities in excess of several international criteria are consistently recorded in harbours. Organochlorine pesticide residues were generally in the 5 ng l?1 range in unfiltered sea water but were significantly higher (1–100) ng g?1 in limited samples of sediment and biota. Additional data requirements to gain further insight into the current state of the Caribbean environment are also identified. A summary of the major land based sources of marine pollution (including sewage, industrial effluents and agricultural run-off) in the insular Caribbean is presented. 相似文献
A generalized bioeconomic simulation model of annual-crop marine fisheries is described and its use in marine fisheries management is demonstrated. The biological submodel represents the recruitment of new organisms into the fishery, the movement of organisms from one fishing area to another and from one depth to another, the growth of organisms and the mortality of organisms resulting both from natural causes and from fishing. The economic submodel represents the fishing effort exerted on each resource species, the monetary costs of fishing, the value of the harvest and the rent (or excess profits) to the fishery.Basic dynamics of the model results from changes in the number of organisms in the fishery over time, which can be summarized as a set of difference equations of the general form ΔN/Δt = R + I ? E ? M ? F where ΔN/Δt is the net change in number of organisms in the fishery over time, R is recruitment, I is immigration, E is emigration, M is natural mortality and F is fishing mortality. R is a driving variable, whereas I, E, M and F are functions of the state of the system at any given point in time. The model can be run in a deterministic or stochastic mode. Values for parameters affecting rates of recruitment, movement, growth, natural mortality and fishing mortality can be selected from uniform, triangular or normal distributions.Use of the model within a fisheries-management framework is demonstrated by evaluating several management alternatives for the pink shrimp (Penaeus duorarum) fishery on the Tortugas grounds in the Gulf of Mexico. Steps involved in use of the model, including parameterization, validation, sensitivity analysis and stochastic simulations of management policies, are explained. 相似文献
Studies of the seasonal distribution of heterotrophic bacteria in Chesapeake Bay (USA) led us to the observation that fungizone was selective for actinomycetes without appreciably altering the total viable aerobic, heterotrophic bacterial counts. A study of the actinomycete populations in the Bay was undertaken, with several media compared for ability to enrich for actinomycetes: basal, casein, Czapek, starch-casein, glycerol-glycine, chitin and oil agar No. 2. Between 40 and 100% of the colonies appearing on chitin and oil No. 2 media were found to be actinomycetes, compared with <2% for the other media employed. It was also found that if sediment samples are frozen, a practice followed when laboratory facilities are not available in the field, a decrease in the total counts and in the actinomycete colony counts occurred. However, on a proportional basis, a slight increase in the percent actinomycetes was noted. A minimum of 21 days incubation time is recommended for recovery of actinomycetes. Also, the absence of NaCl from the actinomycete isolation media and incubation temperatures ≥15°C should give good recoveries of actinomycetes. A seasonal distribution of actinomycetes was noted for Chesapeake Bay, with maximal populations of actinomycetes observed in March and November. Actinomycetes were isolated in the ocean from depths ranging from 7 to 7,790 m. Greater numbers of actinomycetes were isolated using an incubation temperature of 25°C for the estuarine stations and 15°C for the deep-ocean stations. Greater numbers of actinomycetes were associated with polluted environments close to shore. 相似文献
Antarctic fur seals (Arctocephalus gazella) are major secondary consumers in the Southern Ocean, placing them in potential competition with commercial fisheries and requiring research to understand their seasonal habitat use. Using the data obtained during 14 shipboard surveys sampled on a fixed grid (150 K km2) during mid- to late summer, I quantified the spatial distribution and intra-seasonal variability of fur seal sightings relative to distance to land and hydrographic boundaries. I test the hypothesis that fur seals display an increase in their at-sea abundance during mid- to late summer near the Antarctic Peninsula as they prepare to take up wintering grounds. I also test whether abundances of their potential prey, krill and myctophids, exhibit intra-seasonal variability. During midsummer, high-abundance areas are located near major breeding colonies; however, during late summer, there is an order-of-magnitude increase in fur seal abundance, coinciding with an increase in the number of high-abundance areas located in Bransfield Strait. Coincidently, abundance of Euphausia superba decreased and the myctophid Electrona antarctica increased between mid- and late-summer surveys. High-abundance areas of fur seals are not associated with the southern Antarctic Circumpolar Current front but are concentrated within 100 km from land, potentially indicating the location of haul out and important coastal habitat use areas. The dynamic increase in the number and location of high-abundance areas during late summer represents a considerable amount of mammalian predators entering the Antarctic Peninsula marine ecosystem. This information is important for understanding the seasonal impact of fur seals on regional marine food webs and their potential interaction with the autumn–winter krill fishery. 相似文献
The trophic importance of bacteria to harpacticoid copepods in intertidal areas remains poorly understood, and so do the mechanisms of bacterial feeding. It is, for instance, unclear whether harpacticoids directly target bacterial cells or merely co-ingest them with substrates to which bacterial cells may be attached. Here, we investigate bacterial uptake and substrate requirement for four mud intertidal species (Microarthridion littorale, Platychelipus littoralis, Delavalia palustris and Nannopus palustris) by means of 13C-labeled bacteria and biomarker fatty acids (FA). Bacterial uptake strongly depended on grazing on a primary food source but bacterial ingestion rates were low, and no clear indication of copepods directly targeting bacteria was found. Delavalia was the only species that accumulated bacteria-derived FA and gained in polyunsaturated FA (PUFA) probably through bioconversion of bacteria-derived FA. In general, however, our results suggest that bacteria represent a relatively minor and low-quality food for intertidal harpacticoid copepods. 相似文献
A laboratory scale up-flow anaerobic sludge bed (UASB) bioreactor fed with synthetic wastewater was operated with simultaneous methanogenesis and denitrification (SMD) granules for 235 days with a gradient decrease of C/N. Molecular cloning, qRT-PCR and T-RFLP were applied to study the methanogenic community structures in SMD granules and their changes in response to changing influent C/N. The results indicate that when C/N was 20:1, the methane production rate was fastest, and Methanosaetaceae and Methanobacteriaceae were the primary methanogens within the Archaea. The richness and evenness of methanogenic bacteria was best with the highest T-RFLP diversity index of 1.627 in the six granular sludge samples. When C/N was reduced from 20:1 to 5:1, the methanogenic activity of SMD granules decreased gradually, and the relative quantities of methanogens decreased from 36.5% to 10.9%. The abundance of Methanosaetaceae in Archaea increased from 64.5% to 84.2%, while that of Methanobacteriaceae decreased from 18.6% to 11.8%, and the richness and evenness of methanogens decreased along with the T-RFLP diversity index to 1.155, suggesting that the community structure reflected the succession to an unstable condition represented by high nitrate concentrations.
The aim of this study is to analyze the effect of salinity on polycyclic aromatic hydrocarbons (PAHs) biodegradation, community structure and naphthalene dioxygenase gene (ndo) diversity of a halophilic bacterial consortium with the denaturing gradient gel electrophoresis (DGGE) approach. The consortium was developed from oil-contaminated saline soil after enrichment for six times, using phenanthrene as the substrate. The prominent species in the bacterial consortium at all salinities were identified as halophilic bacteria Halomonas, Alcanivorax, Marinobacter, Idiomarina, Martelella and uncultured bacteria. The predominant microbes gradually changed associating with the saline concentration fluctuations ranging from 0.1% to 25% (w/v). Two ndo alpha subunits were dominant at salinities ranging from 0.1% to 20%, while not been clearly detected at 25% salinity. Consistently, the biodegradation occurred at salinities ranging from 0.1% to 20%, while no at 25% salinity, suggesting the two ndo genes played an important role in the degradation. The phylogenetic analysis revealed that both of the two ndo alpha subunits were related to the classic nah-like gene from Pseudomonas stutzeri AN10 and Pseudomonas aeruginosa PaK1, while one with identity of about 82% and the other one with identity of 90% at amino acid sequence level. We concluded that salinity greatly affected halophilic bacterial community structure and also the functional genes which were more related to biodegradation.
Invasions by non-indigenous species have the potential to alter the biodiversity of recipient systems. The magnitude of this
effect often depends on the nature of the invaded communities and the ecology of the invader. We investigated the impacts
of the Japanese seaweed Sargassum muticum (Phaeophyceae, Fucales) on biodiversity in a rocky and sedimentary environment on two islands in the North Sea. In each case,
we compared the epibiota of non-indigenous S. muticum with epibiota communities on taxonomically related and structurally similar native seaweed hosts. Total and average species
richness on S. muticum were similar on the rocky shore (60 species and 22±6 species, respectively) and the sandy shore (64 species and 20±3 species,
respectively). However, community structure and species composition differed significantly between the environments. On the
rocky shore, another native fucoid seaweed, Halidrys siliquosa, supported an epibiota community very similar to that of the invader. On the sandy shore, the only other abundant native
habitat-providing algal species was Fucus vesiculosus. This species supported a different and less diverse assemblage of associated taxa. We conclude that S. muticum enhances epibiota diversity in the sedimentary environment, probably by increasing the substratum availability and habitat
heterogeneity. In contrast, it has negligible impacts on epibiota diversity in the rocky shore environment, where it does
not represent a fundamentally new habitat component. We conclude that even within the same region, the consequences of non-indigenous
species on biodiversity cannot be generalised but depend on the composition and structural complexity of the species in the
recipient community.
This paper is dedicated to Udo Schilling, Chief Diving Officer, Alfred Wegener Institute who trained all of the authors in
the waters off Helgoland to be scientific divers. The work reported here and in previous publications has been made possible
through Udo’s training and support. We remain grateful for his enthusiasm, effort and patience. 相似文献
Pyrene, a representative polycyclic aromatic hydrocarbon (PAH) compound produced mainly from incomplete combustion of fossil fuels, is hazardous to ecosystem health. However, long-term exposure studies did not detect any significant effects of pyrene on soil microorganism. In this study, short-term microcosm experiments were conducted to identify the immediate effect of pyrene on soil bacterial communities. A freshly-collected pristine red soil was spiked with pyrene at 0, 10, 100, 200, and 500 mg·kg-1 and incubated for one day and seven days. The bacterial communities in the incubated soils were analyzed using 16S rRNA sequencing and terminal restriction fragment length polymorphism (T-RFLP) methods. The results revealed high bacterial diversity in both unspiked and pyrene-spiked soils. Only at the highest pyrene-spiking rate of 500 mg·kg-1, two minor bacteria groups of the identified 14 most abundant bacteria groups were completely suppressed. Short-term exposure to pyrene resulted in dominance of Proteobacteria in soil, followed by Acidobacteria, Firmutes, and Bacteroidetes. Our findings showed that bacterial community structure did respond to the presence of pyrene but recovered rapidly from the perturbation. The intensity of impact and the rate of recovery showed some pyrene dosage-dependent trends. Our results revealed that different levels of pyrene may affect the bacterial community structure by suppressing or selecting certain groups of bacteria. It was also found that the bacterial community was most susceptible to pyrene within one day of the chemical addition. 相似文献
Intertidal communities at Macquarie Island (sub-Antarctic) were re-evaluated seven years after a small oil spill resulting
from the grounding of the “Nella Dan”, and six years after the first assessment of biological impact. Sampling was conducted
to evaluate community structure in three zones of the exposed rocky shore (upper red, kelp, and lower red) and in samples
of Durvillaea antarctica holdfasts. There were no significant differences between the community structure in oiled and control locations in any of
the three shore zones, but holdfast macrofaunal communities at oiled sites still showed evidence of impact. Holdfast community-structure
in samples from heavily oiled sites showed moderate levels of recovery, with increased abundances of species which were considered
sensitive to the oiling in the first post-impact studies and decreased abundances of opportunistic polychaete and oligochaete
worms. In contrast, samples collected from the moderately oiled location at Secluded Bay showed little evidence of recovery.
Holdfasts at this site were filled with sediment containing traces of diesel oil, and the macrofaunal community was dominated
by opportunistic worms. This study clearly indicates that even small incidents of anthropogenic perturbation can have long-lasting
consequences for marine communities at Macquarie Island.
Received: 23 July 1997 / Accepted: 5 February 1998 相似文献