首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The incidence of campylobacter enteritis in Lancaster City Health Authority is three times the UK average for similar sizes of population and has marked seasonal peaks in May and June. Environmental monitoring of surface waters around Lancaster showed that thermophilic campylobacters were absent from drinking water from the fells and from the clean upper reaches of the River Conder but were present in the main rivers entering Morecambe Bay, the lower reaches of the River Conder, the Lancaster canal, and seawater from the Lune estuary and Morecambe Bay. All the surface waters tested showed the same seasonality, namely, higher numbers in the winter months and low numbers or none in May, June and July. The absence of thermophilic campylobacters in the summer months may be due to high sunshine levels because experiments on the effects of light showed that campylobacters in sewage effluent and seawater were eliminated within 60 and 30 min of daylight respectively but survived for 24 h in darkness. As the concentrations of campylobacters in surface waters were at their lowest precisely at the time of peak infections in the community it is unlikely that surface waters form Lancaster's reservoir of campylobacter infection for the community.  相似文献   

2.
Until recently, sewage from Morecambe was macerated, but otherwise untreated, and discharged at high water via a short outfall pipe into Morecambe Bay adjacent to a recognized bathing water. In March 1997, a new biological sewage treatment plant came on-line and the effluent was discharged via a longer outfall pipe into the Bay south of Heysham. The effect of the new sewage treatment on the quality of the bathing waters was monitored by testing sea water collected from the three EU designated bathing waters on Morecambe Bay: Morecambe North, Morecambe South and Heysham. After sewage treatment came on-line, the numbers of faecal coliforms and faecal streptococci were lower at Morecambe North and Morecambe South but higher at Heysham. Although the changes in numbers were not always statistically significant, they were sufficient to affect compliance with the EU Bathing Water Directive Imperative (mandatory) standards. Compliance improved markedly at Morecambe North and South but declined at Heysham, the closest bathing site to the new outfall. Numbers of thermophilic campylobacters were similar in both years, which is suggestive of their sources being different from those of the indicator bacteria. Campylobacter lari and urease-positive thermophilic campylobacters (UPTC) were the only species of Campylobacter isolated from Morecambe's bathing waters. Very low numbers of Salmonella were found, with Salm, arizonae the only species isolated.  相似文献   

3.
Environmental monitoring of thermophilic campylobacters in liquid sewage effluent (primary settlement only) during 1988 and 1989 showed a prominent seasonality with distinct peaks in May and June (the average number of bacteria per 100 ml of effluent in months other than May and June was 2244 and the average for the peak months was 50,778). Apart from September 1989, this seasonality coincided precisely with the seasonal variation of campylobacter enteritis in the community with similar distinct peaks in May and June (the incidence of infection in May and June was twice or three times that in the other months). Sampling of sewers showed that the campylobacters in the sewage effluent came mainly from abbatoir and animal processing plants with only a minor input from the community. Therefore, the seasonal peaks in the sewage effluent and in the community may not be dependent on human infections but on zoonotic infections which may also peak in May and June.  相似文献   

4.
AIMS: To determine whether diurnal and seasonal variations in campylobacters in surface waters result from the effects of temperature and u.v. radiation, and whether natural populations of Campylobacter lari and urease-positive thermophilic campylobacters (UPTC) from birds survive better in surface waters than Camp. jejuni from sewage. METHODS AND RESULTS: Natural populations of Camp. lari and UPTC in sea water, and Camp. jejuni in river water, were exposed to artificial sunlight (equivalent to a sunny day in June). Both populations became non-culturable within 30 min, with T90s of 15 min and 25 min, respectively. Cultures of Camp. jejuni became non-culturable within 40 min and those of Camp. coli, Camp. lari and UPTC, within 60 min. In darkness, survival was temperature-dependent. Natural populations took 12 h at 37 degrees C and 5 days at 4 degrees C to become non-culturable in sea water, and slightly less in river water. Cultures of Camp. lari and UPTCs survived for significantly longer than Camp. jejuni and Camp. coli. Loss of culturability for all isolates was most rapid at 37 degrees C and slowest at 4 degrees C. Newly isolated strains from sea water and river water behaved in an almost identical manner to NCTC strains. CONCLUSION: Campylobacter lari and UPTCs survive for longer in surface waters than Camp. jejuni and Camp. coli, particularly in the dark. Low Campylobacter numbers in coastal waters in the summer, especially in the afternoon, are due to the combined effects of higher temperatures and higher levels of u.v. radiation. SIGNIFICANCE AND IMPACT OF THE STUDY: Campylobacter lari and UPTCs from birds predominate in bathing waters in Morecambe Bay because they are better able to survive; they also originate from closer to the shore than Camp. jejuni and Camp. coli in sewage effluent, which survive poorly and die before the incoming tide reaches the shore. The predominance of Camp. jejuni in river water results from its dominance of the inputs and not from its ability to survive.  相似文献   

5.
Environmental monitoring of thermophilic campylobacters in liquid sewage effluent (primary settlement only) during 1988 and 1989 showed a prominent seasonablity with distinct peaks in May and June (the average number of bacteria per 100 ml of effluent in months other than May and June was 2244 and the average for the peak months was 50 778). Apart from September 1989, this seasonality coincided precisely with the seasonal variation of Campylobacter enteritis in the community with similar distinct peaks in May and June (the incidence of infection in May and June was twice or three times that in the other months).
Sampling of sewers showed that the campylobacters in the sewage effluent came mainly from abbatoir and animal processing plants with only a minor input from the community. Therefore, the seasonal peaks in the sewage effluent and in the community may not be dependent on human infections but on zoonotic infections which may also peak in May and June.  相似文献   

6.
Seasonal variation of thermophilic campylobacters in sewage sludge   总被引:3,自引:0,他引:3  
The seasonal variation of thermophilic campylobacters in Lancaster's sewage sludge was studied over a 21 month period. The numbers in fresh sludge (from primary sedimentation) vary between approximately 200 and 5000/100 ml for most of the year but there was a large increase in May and June (in May 1988 there were 42,100 campylobacters/100 ml which is 17 times more than in the preceding April). In 1989 there was a similar May/June peak but with lower numbers. This seasonal variation, measured by environmental monitoring, reflects the incidence of infections in the community. The same pattern was found in 2-d old sludge but the numbers were substantially lower (40% lower over the experimental period). Thermophilic campylobacters were virtually absent from digested sludge and sludge prior to land distribution. Survival experiments confirm that campylobacters survive for only a few hours in both sterile and unsterile digested and undigested sludge. These results suggest that it is safe to dispose of Lancaster's digested sludge on land but there is still uncertainty about the ability of campylobacters to survive in sludge in the viable but non-culturable form.  相似文献   

7.
Seasonal variation of thermophilic campylobacters in sewage sludge   总被引:4,自引:3,他引:1  
The seasonal variation of thermophilic campylobacters in Lancaster's sewage sludge was studied over a 21 month period. The numbers in fresh sludge (from primary sedimentation) vary between approximately 200 and 5000/100 ml for most of the year but there was a large increase in May and June (in May 1988 there were 42100 campylobacters/100 ml which is 17 times more than in the preceding April). In 1989 there was a similar May/June peak but with lower numbers. This seasonal variation, measured by environmental monitoring, reflects the incidence of infections in the community. The same pattern was found in 2-d old sludge but the numbers were substantially lower (40% lower over the experimental period).
Thermophilic campylobacters were virtually absent from digested sludge and sludge prior to land distribution. Survival experiments confirm that campylobacters survive for only a few hours in both sterile and unsterile digested and undigested sludge. These results suggest that it is safe to dispose of Lancaster's digested sludge on land but there is still uncertainty about the ability of campylobacters to survive in sludge in the viable but non-culturable form.  相似文献   

8.
Aims: To determine the prevalence of Campylobacter in surface waters of a highly populated Mediterranean area. Methods and Results: Surface water and wastewater samples were collected from an area in the north‐east of Spain during a 2‐year study. All the samples were analysed using the MPN method and Multiplex PCR to quantify and identify Campylobacter. It was detected in 82% of the samples from the Llobregat River with a mean of 1·3 MPN 100 ml?1. The lowest counts were obtained in summer. Campylobacter coli was the predominant species in this river. The bacteria were isolated from marsh water but not from seawater samples. The highest counts of campylobacters were found in poultry wastewater where Camp. jejuni was the predominant species, as in urban sewage. In pig slurry, Camp. coli was the only species detected. Conclusions: Campylobacter jejuni and Camp. coli are present and widely distributed in the surface water of the studied area. The two species co‐exist, with Camp. coli being predominant. In river water, campylobacter counts presented a seasonal distribution. No relationship with faecal indicators was found. Significance and Impact of the Study: This study provides the first data on the occurrence and concentrations of thermotolerant campylobacter species in surface water in a Mediterranean area.  相似文献   

9.
根据2007年5月、2008年5月和6月对长江口及其邻近水域渔业底拖网调查资料,分析了该水域大型水母资源量变化对渔业种类组成、分布和资源量的影响.结果表明:2007年5月-2008年6月,大型水母的平均网获量和最高网获量增加,2008年6月平均网获量为222.2 kg·h-1,最高网获量达到1800 kg·h-1.大型水母主要分布在50 m等深线附近,及100m等深线以浅的东海沿岸流、长江径流和台湾暖流的锋面上,6月大型水母的集中分布范围与5月相比向北偏移,在2007年5月和2008年5月两次调查中均存在一个水母集中分布点(122.5° E,28.5° N).大型水母和渔业资源呈交错分布,大型水母集中分布的区域,渔业资源网获量降低,种类组成也发生了显著变化.在水母网获量高的站位主要以小型种类(竹筴鱼、龙头鱼、发光鲷等)或中上层种类(刺鲳、长蛸)及带鱼为主,刺鲳在2008年6月的调查中占整个渔获量的23.7%,小黄鱼也占有较高的比重,但一些底层种类如黄鮟鏮等在水母集中分布区没有发现,虾蟹类也相对较少.大型水母对长江口渔业生态系统的群落结构和资源量都产生了一定的影响,而且水母可以通过营养级联反应改变系统的能流方式.因此,在保护渔业资源和制定相关的渔业管理措施时,建议将水母作为一个独立的生态类群来考虑.  相似文献   

10.
Quantitative zooplankton samples were obtained monthly or bi-monthly 15 times from June 1974 to May 1975 at three stations in lower Delaware Bay. Two 12-hour cruises were also conducted at one of the stations.Arthropods dominated the samples in terms of number of species and number of individuals. The number of zooplankton from surface samples ranged from 58/m3 in August to 21,092/ m3 in June, while bottom samples varied from 259/m3 in August to 30,395/ m3 in October. In general, larger concentrations of individuals were found in bottom samples.Only on three occasions did meroplankton exceed the holoplankton, and these occurred at the shallow water stations. Meroplankton comprised a larger percentage of the bottom samples than surface samples. Zoeae of Neopanope sayi and Uca sp. contributed mainly to the large proportion of meroplankton in July 1974, veligers of Mytilus edulis in January 1975, and nauplii of Balanus sp. in May 1975.Copepods were the largest component of the population throughout most of the year. At all stations and depths, Arctica tonsa dominated most of the summer samples. In the spring of 1975, A. tonsa was replaced by Centropages hamatus, Temora longicornis, and Pseudocalanus minutus.During the 12-hour cruises there were higher numbers of individuals in the bottom waters in the day with migration to surface waters in the afternoon and evening. Based on cluster analysis, five time-related assemblages were discerned: June, July–August, September–November, December, January–May. Comparison of Delaware Bay zooplankton with other estuarine systems indicated that the densities obtained locally were most similar to those reported in the York River, Virginia.  相似文献   

11.
Monitoring of thermophilic campylobacters in two Libyan seawage treatment plants has shown that the communities of Tripoli and Sabratha almost certainly harbour campylobacters capable of producing enteritis. The plant in Tripoli eradicated the campylobacters from effuent by secondary treatment with trikling filtration followed by chlorination. The plant ant Sabratha, which was not working well at the time of sampling, reduced campylobacter numbers by only 53% and 74% during secondary teatment in a stabilization pond, and a reservoir in Sabratha, which received effluent from the stabilization pond and which supplies water for irrigation, also contained thermophilic campylobacters. In both treatment plants campylobacters were eradicated from sewage sludge by digestion and drying.  相似文献   

12.
A simple method for detection and enumeration of alkylbenzenesulfonate (ABS)-degrading microorganisms by using agar plates was developed and used in microbiological studies of coastal marine and polluted river waters. The method depends upon the color responses of neutral red in alkaline medium. Neutral red changes from pink, when it enters into ABS micelles, to yellow, when the ABS is degraded, and does not form micelles. When neutral red-tris(hydroxymethyl)-aminomethane buffer solution and then cationic surfactant solution were sprayed onto the agar surface of ABS-nutrient agar cultures, transparent haloes appeared around the colonies of ABS-degrading microorganisms against a pink background. Viable counts of ABS-degrading bacteria isolated from both seawater and freshwater environments were considerably higher in polluted waters than in less polluted areas. Viable counts of ABS-degrading bacteria averaged 1.5 x 105/ml in samples from the surface water of polluted Tokyo Bay and 3.0 x 104/ml in samples from the surface water of polluted Tamagawa River but were fewer in number in samples from less polluted waters.  相似文献   

13.
我国近海赤潮多发区域及其生态学特征   总被引:7,自引:1,他引:6  
根据有关的研究资料,分析我国近海赤潮多发区分布、主要赤潮生物种类、环境状况及赤潮发生生态学特点.结果表明,我国辽东湾、渤海湾、莱州湾、大连湾、长江口、舟山海域、杭州湾、厦门湾、柘林湾、大鹏湾、珠江口等为赤潮多发区.引发赤潮的因素较多,它与气象、水动力、营养盐及生物环境的变化密切相关,人类活动(如海水养殖、陆源污水排放等)影响加剧近海富营养化是引发赤潮的重要因素;但富营养化并非发生赤潮的唯一条件,低营养海区也可能发生赤潮.目前对诱发赤潮的关键因子及赤潮发生机理,应加强定点长期监测和开展深入研究.  相似文献   

14.
Seasonal changes in the abundance of fish species inhabiting an intertidal mussel bed in Morecambe Bay, Lancashire, were studied from 1956 to 1972 (excluding 1962). Species distribution was to some extent governed by the availability of suitable habitats. Competition for living space created by high numbers of a particular species resulted in an extension of its normal vertical distribution pattern. Correlations between seasonal migrations and sea temperatures or suggested breeding periods are postulated. The effects of the severe winter of 1962-63 are compared with published information from other locations around the British Isles.  相似文献   

15.
Slurry storage tanks on Lancashire farms were sampled in May, June, October and November. There was a seasonal pattern in the number of thermophilic campylobacters. The average log10 MPN per gram fresh weight (log10 MPN gfw−1) in stored samples in May and June was 0·78 ( S.D. 0·71) compared to 2·07 ( S.D. 0·70) in November and December. Campylobacters were readily detected in samples of mature slurry and composted bedding that farmers were about to put to land. The survival of campylobacters in slurry sprayed on land was studied in two seasons. In June, on farm A, stored slurry was mechanically aerated for 48 h and very low numbers of campylobacters (0·9 log10 MPN gfw−1) remained in the slurry before it was sprayed onto land. They became undetectable within 24 h once sprayed on land. In contrast, campylobacters in matured but unaerated slurry that was sprayed onto land on farm B in February were still detectable in samples taken 5 d after application to land, dropping from 2·11 log10 MPN gfw−1–1·37, a decline of only 0·74 log10 MPN gfw−1 in the first 5 d after application.  相似文献   

16.
The epidemiology of clinical cases of campylobacter in temperate climates shows a striking seasonality. In the search for a seasonal environmental reservoir changes in the carriage rate and population size of campylobacters in bovine hosts with time have been measured. Most probable number (MPN) methodology was used to enumerate thermophilic campylobacters in samples taken from the small intestines of beef cattle at slaughter and the fresh faeces of four dairy herds and new-born calves. Statistical analyses revealed significant evidence for seasonal periodicity in the data from dairy herds ( P = 0·044). Not only was there a departure from constancy within a 12-month interval but these data revealed a true seasonality, that is, the same periodicity in numbers from one year to the next. Each herd had two peaks per year, in approximately spring and autumn. Peaks coincided in herds on neighbouring farms but those on farms in the north preceded those on farms in the south by 2 and 1 months, respectively ( P = 0·0057). Intestinal carriage by beef cattle at slaughter was 89·4% ( n = 360) with an average MPN campylobacters per gram fresh weight (MPN gfw−1) of 6·1 × 102. Average MPN gfw−1 in faeces from the dairy herds and calves were 69·9 ( S.D. 3) and 3·3 × 104 ( S.D. 1·7 × 102). There was no evidence of seasonal periodicity in the size of the campylobacter population in beef cattle at slaughter. Calves were campylobacter free at birth but became colonized within a few days.  相似文献   

17.
Larvae of 63 Bivalvia taxa were found in Amursky Bay. Of these, 47 were identified to the species level. Larvae of 55 taxa were found throughout the bay. The highest species diversity was recorded in the northeastern part and in the center of the southern part of the bay, as well as at the exit from it. Larvae of Mactra chinensis, Mytilus coruscus, Crassostrea gigas, Teredo navalis, Mya japonica, and Mysella ventricosa were widely distributed in the bay. The maximum numbers of species were observed in July and September. A comparison of species lists using the set-theory method showed that the species complexes typical of different parts of Amursky Bay are formed under the influence of the Razdolnaya River runoff flow from the north and marine waters coming from the south. The mean density of larvae during the observation period was 1100 specimens/m3 in the northern and 735 specimens/m3 in the southern part of the bay. The highest density of larvae in Amursky Bay was observed at the end of June, the beginning of July, and in September; the minimal larval density occurred in April, May, and August. While the species diversity was similarly high, the density of larvae was significantly higher in Amursky Bay than in the nearby Ussuriisky Bay.  相似文献   

18.
Sepiola atlantica were captured in seine nets at twelve locations around the coast of Anglesey, UK. Animals were most abundant on the very sheltered shore of Y Foryd Bay and the wave-exposed shore of Traeth Penrhos, and these two locations were further sampled seasonally to examine the seasonal occurrence, population structure and reproductive biology of S. atlantica. Sepiola atlantica (5?C28?mm dorsal mantle length (DML)) migrated inshore seasonally and first appeared in July where they attained peak abundances between July and August at seawater temperatures of 17°C. Numbers declined between September and October as temperatures fell below 15?C16°C, and in late October, they migrated offshore. Male S. atlantica was significantly smaller and matured at a smaller DML than females. The number of spermatangia on the bursa copulatrix of female S. atlantica varied seasonally attaining maximum numbers in October with a mean of 22 spermatangia on the bursa copulatrix of Y Foryd Bay females. At Y Foryd Bay and Traeth Penrhos, the number of spermatophores in male and potential fecundity in female S. atlantica ranged between 1 and 147 and 25 and 141, respectively. The spermatophoric complex and gonadosomatic index showed a high degree of variability in individuals of similar wet body weight with the female gonad constituting a far greater percentage of the total wet body weight than the male gonad. It is concluded that S. atlantica of all sizes and maturity stages congregate in the shallow waters around Anglesey between July and October when environmental conditions are favourable for enhanced growth and maturation and where the high numbers of animals enhance opportunities for mating.  相似文献   

19.
John Niles  David Rice 《Bird Study》2013,60(3):175-176
Large numbers of Ringed Plovers pass through Morecambe Bay in spring, believed bound for Greenland. In autumn, when numbers are smaller, two separate stocks are involved: a moulting population drawn from temperate Europe (some of which overwinter), and birds of arctic origins which pause to put on weight but do not moult there.  相似文献   

20.
The present report presents the first evidence of disseminated neoplasia (DN) in cockles Cerastoderma edule from Arcachon Bay (France). Aneuploidy of neoplastic cells allowed the use of flow cytometry (FCM) to diagnose and stage DN. A 1 year survey (2007) of the prevalence and intensity (% of aneuploid circulating cells in neoplastic cockles) was conducted. Prevalences ranged from 2.2% (June) to 13.6% (May), and disease intensity ranged from 18.7% (June) to 95.5% (September). These percentages were not correlated with seawater temperature, but rather showed unexplained oscillations over the year. Prevalence and intensity of DN were higher in cockles found at the surface of sediment compared to those buried normally (11.8% vs. 6.7% and 53.0% vs. 40.6%, respectively, p < 0.05). DN could thus be one mechanism leading to unexplained presence of cockles at the surface of the sediment in Arcachon Bay. Ploidy characteristics of neoplastic cells were also investigated using FCM, revealing an unusual, broad continuum of ploidy distribution from 1.6 to 9.6n. Ploidy values were not in whole numbers in contrast to the rounded values reported in other studies. Ploidy varied according to DN intensity, with the ploidy distribution of neoplastic cells from lightly-diseased cockles being unimodal (3.7n median). In contrast, highly-diseased cockles showed a bimodal ploidy distribution (3.0n and 4.7n medians). This suggests that, in cockles from Arcachon Bay, mechanisms leading to aneuploidy are complex, developing during disease progression.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号