Recreational exposure to low concentrations of microcystins during an algal bloom in a small lake          下载免费PDF全文

Backer LC  Carmichael W  Kirkpatrick B  Williams C  Irvin M  Zhou Y  Johnson TB  Nierenberg K  Hill VR  Kieszak SM  Cheng YS 《Marine drugs》2008,6(2):389-406

We measured microcystins in blood from people at risk for swallowing water or inhaling spray while swimming, water skiing, jet skiing, or boating during an algal bloom. We monitored water samples from a small lake as a Microcystis aeruginosa bloom developed. We recruited 97 people planning recreational activities in that lake and seven others who volunteered to recreate in a nearby bloom-free lake. We conducted our field study within a week of finding a 10-μg/L microcystin concentration. We analyzed water, air, and human blood samples for water quality, potential human pathogens, algal taxonomy, and microcystin concentrations. We interviewed study participants for demographic and current health symptom information. Water samples were assayed for potential respiratory viruses (adenoviruses and enteroviruses), but none were detected. We did find low concentrations of Escherichia coli, indicating fecal contamination. We found low levels of microcystins (2 μg/L to 5 μg/L) in the water and (<0.1 ng/m³) in the aerosol samples. Blood levels of microcystins for all participants were below the limit of detection (0.147μg/L). Given this low exposure level, study participants reported no symptom increases following recreational exposure to microcystins. This is the first study to report that water-based recreational activities can expose people to very low concentrations of aerosol-borne microcystins; we recently conducted another field study to assess exposures to higher concentrations of these algal toxins.  相似文献   

Genetic and morphological characterization of Mawsonascaris vulvolacinata n. sp. (Nematoda: Anisakidae) and associated histopathology in a wild caught cowtail stingray,Pastinachus ater     

Shokoofeh Shamsi  Mai Dang  Xiaocheng Zhu  Barbara Nowak 《Journal of fish diseases》2019,42(7):1047-1056

There are limited reports of infectious agents affecting Australian cowtail stingrays. In the present study, a new species of ascaridoid nematode belonging to the genus Mawsonascaris is described. The most distinct characteristic features were observed in females (the presence of a polar spine in the eggs and a flap‐like projection in the vulval area). An identification key for Mawsonascaris spp. is provided. Additionally, internal transcribed spacers (ITS) sequences were obtained for the new species. Alignment of the ITS sequence of the specimens in the present study with those deposited in GenBank showed that there exists no other highly similar sequence. Phylogenetic analyses resulted in a distinct grouping of our specimens supporting morphological distinction from previously described Mawsonascaris spp. Histology was used to investigate the pathology caused by the infection. Necrosis, inflammation and fibrosis were evident at the border of the nodules formed by parasite. A large number of parasites were present in muscularis mucosae and submucosa but not in the muscularis of the stomach. The parasites were associated with an increased inflammatory response, which was also found in the muscularis mucosae and submucosa. Similar pathology has been described in elasmobranchs infected by cestodes, although with more severe lesions.  相似文献   

Systemic infection in European perch with thermoadapted virulent Aeromonas salmonicida (Perca fluviatilis)     

Melanie Rupp  Paola Pilo  Barbara Müller  Ralph Knüsel  Beat von Siebenthal  Joachim Frey  Paul‐Daniel Sindilariu  Heike Schmidt‐Posthaus 《Journal of fish diseases》2019,42(5):685-691

In non‐salmonid fish, Aeromonas salmonicidacan cause local infections with severe skin ulcerations, known as atypical furunculosis. In this study, we present a systemic infection by a virulent A. salmonicidain European perch (Perca fluviatilis).This infection was diagnosed in a Swiss warm water recirculation aquaculture system. The isolate of A.  salmonicida encodes a type three secretion system (TTSS) most likely located on a plasmid similar to pAsa5/pASvirA, which is known to specify one of the main virulence attributes of the species A. salmonicida. However, the genes specifying the TTSS of the perch isolate show a higher temperature tolerance than strains isolated from cold‐water fish. The function of the TTSS in virulence was verified in a cytotoxicity test using bluegill fry and epithelioma papulosum cyprinid cells.  相似文献   

Effect of line shooter and mainline tension on the sink rates of pelagic longlines and implications for seabird interactions     

Graham Robertson  Steven G. Candy  Barbara Wienecke 《水产资源保护:海洋与淡水生态系统》2010,20(4):419-427

1. The likelihood that seabirds will be hooked and drowned in longline fisheries increases when baited hooks sink slowly. Fishermen target different fishing depths by setting the mainline through a line shooter, which controls the tension (or slackness) in the line. An experiment was conducted in Australia's pelagic longline fishery to test the hypothesis of no difference in sink rates of baited hooks attached to mainline set under varying degrees of tension. 2. Mainline was set in three configurations typically used in the fishery: (a) surface set tight with no slackness astern; (b) surface set loose with 2 s of slack astern; and (c) deep set loose with 7 s of slack astern. 3. Tension on the mainline had a powerful effect on sink rates. Baited hooks on branch lines attached to tight mainlines reached 2 m depth nearly twice as fast as those on the two loose mainline tensions, averaging 5.8 s (0.35 m s^?1) compared with 9.9 s (0.20 m s^?1) and 11.0 s (0.18 m s^?1) for surface set loose and deep set loose tensions, respectively. 4. The likely reason for the difference is propeller turbulence. Tight mainline entered the water aft of the area affected by turbulence whereas the two loose mainlines and the clip ends of branch lines were set directly into it about 1 m astern of the vessel. The turbulence presumably slowed the sink rates of baited hooks at the other end of the branch lines. 5. The results suggest that mainline deployed with a line shooter (as in deep setting) into propeller turbulence at the vessel stern slows the sink rates of baited hooks, potentially increasing their availability to seabirds. Unless mainline can be set to avoid propeller turbulence the use of line shooters for deep setting should not be promoted as an effective deterrent to seabirds. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Experimental deepwater culture of the Sydney rock oyster (Crassostrea commercialis = Saccostrea cucullata): II. Pontoon tray cultivation     

Baughan Wisely  John E. Holliday  Barbara L. Reid 《Aquaculture (Amsterdam, Netherlands)》1979,16(2):141-146

Pontoons made from plastic pipe were tested as an alternative to racks for deepwater culture of the Sydney rock oyster. The growth and mortality of oysters permanently suspended in water on trays beneath floating pontoons were compared with oysters on trays in an intertidal zone. For both culled spat (30–31 g whole oyster weight) and seconds oysters (37–39 g) beneath pontoons the growth rate, measured by weight increases, was three times that of oysters on intertidal racks over a 5-month period. Mortality (from unknown causes) was higher beneath the pontoons. The mean mortality of spat oysters was 40% compared with 24% on the intertidal trays, and for seconds oysters was 51% compared with 34%.  相似文献   

The colonisation by plants of calcareous wastes from the salt and alkali industry in Cheshire,England     

J.A. Lee  Barbara Greenwood 《Biological conservation》1976,10(2):131-149

Calcareous wastes from the salt industry occupy approximately 150ha of land in Cheshire, a county devoid of natural calcareous substrata. The wastes are pumped into lagoons and on drying put become colonised by plants. The resulting lime beds vary in the extent to which they are invaded by plants but a number of areas support rich and varied grassland communities. The Witton lime beds, Northwich, support large populations of a number of species of base-rich habitats, which are uncommon in Cheshire and are of restricted distribution in northwest England as a whole. These include a number of orchid species, of which Dactylorhiza praetermissa and Gymnadenia conopsea are the most abundant. Information analysis was used to analyse the vegetation of Witton lime beds and the vegetation groupings recognised were used to examine possible successional sequences. The edaphic factors limiting growth in lime wastes were examined and the effects of fertilizer additions on the growth of indigenous species at Witton are described. Phosphorus was the major element limiting growth but on older wastes, with a higher unreacted lime content, phosphorus only partially removed the infertility. The findings are discussed in terms of the conservation and management of Witton lime beds to ensure continued floristic diversity and the possible reclamation of other lime waste areas.  相似文献   

A principal components analysis of some biochemical activities in a climosequence of soils     

D.J. Ross  T.W. Speir  D.J. Giltrap  Barbara A. McNeilly  L.F. Molloy 《Soil biology & biochemistry》1975,7(6):349-355

Ten biochemical properties, comprising oxygen uptakes with and without added glucose, dehydrogenase, invertase, amylase. protease, urease, phosphatase, and sulphatase activities, and the invertase/amylase ratio, were measured in a climosequence of nine soils in tussock grasslands in New Zealand. Generally, these properties had no consistent distribution pattern. Some activities, however, were greater in the more developed soils of the sequence while others were lower in the “alpine” soil.The influence of 10 environmental and soil factors on the activities was assessed by principal components analysis. Nearly 90% of the total variance could be accounted for by only three components. The amounts of variance in individual activities accounted for by these components differed, but were usually high. The percentage of organic C, soil moisture regime, and mean annual temperature accounted for much of the variance in all three components; total N was unimportant. As a result of the principal components analysis, the soils could be grouped biochemically into arrangements that were consistent with either the pedological classification of the soils or the influence of a dominant environmental factor. The usefulness of principal components analysis for other ecological studies of soil biochemical properties is indicated.  相似文献   

Connecting phenological predictions with population growth rates for mountain pine beetle,an outbreak insect   总被引：1，自引：0，他引：1  

James A. Powell  Barbara J. Bentz 《Landscape Ecology》2009,24(5):657-672

It is expected that a significant impact of global warming will be disruption of phenology as environmental cues become disassociated from their selective impacts. However there are few, if any, models directly connecting phenology with population growth rates. In this paper we discuss connecting a distributional model describing mountain pine beetle phenology with a model of population success measured using annual growth rates derived from aerially detected counts of infested trees. This model bridges the gap between phenology predictions and population viability/growth rates for mountain pine beetle. The model is parameterized and compared with 8 years of data from a recent outbreak in central Idaho, and is driven using measured tree phloem temperatures from north and south bole aspects and cumulative forest area impacted. A model driven by observed south-side phloem temperatures and that includes a correction for forest area previously infested and killed is most predictive and generates realistic parameter values of mountain pine beetle fecundity and population growth. Given that observed phloem temperatures are not always available, we explore a variety of methods for using daily maximum and minimum ambient temperatures in model predictions.  相似文献   

Modelling multi-species response to landscape dynamics: mosaic cycles support urban biodiversity     

Mira Kattwinkel  Barbara Strauss  Robert Biedermann  Michael Kleyer 《Landscape Ecology》2009,24(7):929-941

The importance of the spatial as well as the temporal structure of habitat patches for urban biodiversity has been recognised, but rarely quantified. In dynamic environments the rate of habitat destruction and recreation (i.e. the landscape turnover rate), the minimum amount of potential habitat, its spatial configuration as well as the environmental conditions determining habitat quality are crucial factors for species occurrence. We analysed species responses to environmental parameters and to the spatio-temporal configuration of urban brownfield habitats in a multi-species approach (37 plant and 43 insect species). Species presence/absence data and soil parameters, site age, vegetation structure and landscape context were recorded by random stratified sampling at 133 study plots in industrial areas in the city of Bremen (Germany). Based on the field data, we predicted species occurrences by species distribution models using a multi-model inference approach. Predicted species communities were driven by successional age both at the scale of a single building lot and at the landscape scale. Minimum average succession time of brownfield habitats required to support all and especially regionally rare species depended on the proportion of available open space; the larger the potential habitat area the faster the acceptable turnover. Most plant, grasshopper, and leafhopper species modelled could be maintained at an intermediate turnover rate (mean age of 10–15 years) and a proportion of open sites of at least 40%. Our modelling approach provides the opportunity of inferring optimal spatio-temporal landscape configurations for urban conservation management from patch scale species-environment relationships. The results indicate that urban planning should incorporate land use dynamics into the management of urban biodiversity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Washing agents from sewage sludge: efficiency of Cd removal from highly contaminated soils and effect on soil organic balance     

Klik  Barbara  Kulikowska  Dorota  Gusiatin  Zygmunt M.  Pasieczna-Patkowska  Sylwia 《Journal of Soils and Sediments》2020,20(1):284-296

Purpose

To compare Cd removal from different soils with three washing agents recovered from sewage sludge (dissolved organic matter (DOM), soluble humic-like substances (HLS), soluble humic substances (SHS)). Also, to investigate how washing with these agents changes soil organic-matter composition (OM).

Materials and methods

Sandy clay loam (S1) and clay (S2) highly contaminated with Cd (300 mg kg^?1) were washed with DOM, HLS, or SHS solutions at various pHs, and with various washing times and washing modes (single or double). Cd distribution and OM composition were determined (including content of humic substances (HS), fulvic fraction (FF), labile humic acids (L-HA), and stable humic acids (S-HA)).

Results and discussion

Cd removal proceeded with pseudo-second-order kinetics. Equilibrium was reached in 30 min (S1) and 60 min (S2). DOM, HLS, and SHS removed 75–82% of Cd from S1, and 80–87% from S2. The most mobile fraction of Cd was removed after one wash. S2 retained more OM, including HS, than S1. Although washing did not change the HA/FF ratio in most variants, washing with DOM and HLS increased the percentage of L-HA in both soils. Washing with SHS increased S-HA content in both soils, but the percent content of S-HA was similar to that in the unwashed soil.

Conclusions

DOM, HLS, and SHS derived from sewage sludge can effectively remediate clay and sandy clay soils highly contaminated with Cd. Washing with an SHS solution can increase the content of the most stable carbon forms (HA), which is beneficial for carbon sequestration in remediated soils.

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