Periphytic biofilms in aquaculture waters are thought to improve water quality, provide an additional food source, and improve the survival and growth of some reared animals. In the AsiaPacific region, particularly in...Periphytic biofilms in aquaculture waters are thought to improve water quality, provide an additional food source, and improve the survival and growth of some reared animals. In the AsiaPacific region, particularly in China, artificial reefs are commonly used in the commercial farming of sea cucumbers. However, few studies have examined the epilithic biofilms on the artificial reefs. To gain a better understanding of the succession of epilithic biofilms and their ecological processes in sea cucumber culture waters, two experiments were conducted in culture waters of the sea cucumber Apostichopus japonicus in Rongcheng, China, using artificial test panels. On the test panels of succession experiment, more than 67 species were identified in the biofilms. On the test panels of seasonal variation experiment, more than 46 species were recorded in the biofilms. In both experiments, communities of epilithic biofilms were dominated by diatoms, green algae and the annelid Spirorbis sp. In the initial colonization, the dominant diatoms were Cocconeis sp., Amphora spp. and Nitzschia closterium in June, which were succeeded by species of Navicula, Cocconeis and Nitzschia(July to September), and then by Licmophora abbreviata, Nitzschia closterium and Synedra spp. in the following months. A diatom bloom in the autumn and filamentous green algae burst in the summer were also observed. Ecological indices well annotated the succession and seasonal changes in epilithic communities. Multidimensional scaling(MDS) analysis found significant differences in diatom community composition among months and seasons. Fast growth of biofilms was observed in the summer and autumn, whereas the biomass of summer biofilms was largely made up of filamentous green algae. Present results show that the components of epilithic biofilms are mostly optimal foods of A. japonicus, suggesting that biofilms on artificial reefs may contribute important nutritional sources for sea cucumbers during their growth seasons. Future works should include quantitative determination of the contribution of epilithic biofilms to the diet of A. japonicus, potential roles of epilithic biofilms in regulating the water quality of sea cucumber ponds, and the regulation of epilithic biofilms in sea cucumber culture ponds.展开更多
Virulence factors(VFs)confer upon pathogens the ability to cause various types of damage or diseases.Wastewater treatment plants(WWTPs)are important point sources for the emission of pathogens and VFs into receiving r...Virulence factors(VFs)confer upon pathogens the ability to cause various types of damage or diseases.Wastewater treatment plants(WWTPs)are important point sources for the emission of pathogens and VFs into receiving rivers.Conventional WWTP upgrades are often implemented to improve the water quality of receiving ecosystems.However,knowledge on the pathogens,VFs,and health risks to receiving aquatic ecosystems after upgrade remains limited.In this study,we investigated detailed pathogenic information,including taxa,pathogenicity,and health risk,in two wastewater-dominant rivers after WWTP upgrade.Using 16S rRNA gene sequencing,we screened 14 potential pathogens in water and epilithic biofilm samples,though they were significantly more enriched in the biofilms.Combining 16S rRNA and metagenomic sequencing data,we identified Pseudomonas and Aeromonas as the dominant pathogenic taxa carrying functional VFs(e.g.,mobility and offensive)in the epilithic biofilm.Moreover,strong pathogen-specific VF-host co-occurrence events were observed in the epilithic biofilm samples,indicating the importance of biofilms as reservoirs and vehicles for VFs.Further,we demonstrated that mobility VF is crucial for biofilm formation and pathogens in biofilm carrying offensive VF may be highly invasive.Quantification and health risk assessment suggested that the skin contact risk of P.aeruginosa carrying VFs was higher than the acceptable probability of 10^(-4)in both water and epilithic biofilm samples,which may threaten ecological and human health.展开更多
Spatial biomass variation and community structure of epilithic biofilms were examined using cell counts, chlorophyll a extraction, and remote-sensing techniques. Samples were collected at two levels of wave exposure a...Spatial biomass variation and community structure of epilithic biofilms were examined using cell counts, chlorophyll a extraction, and remote-sensing techniques. Samples were collected at two levels of wave exposure along the Yellow and East Coasts of Korea in December 2010. Cyanobacteria were dominant, occupying about 88% of biofilm, irrespective of wave exposure levels. The cyanobacteria species, Aphanotece spp. was abundant in the Yellow Coast location and Lyngbya spp. was abundant in the East coast location. The representative diatoms were Navicula spp. and Achnanthes spp. on the rocky shores of all study sites. Average Normalized Difference Vegetation Index (NDVI) was significantly greater in the Yellow Coast (mean 0.46) than that in the East Coast (mean 0.21);a similar pattern was observed in Vegetation Index (VI). Chlorophyll a content was three times greater on the Yellow Coast (20.50 μg/cm2) than that on the East Coast (8.21 μg/cm2), and it was greater at the Gosapo and Bangpo shore sites than that at the Gyeokpo site, on the Yellow Coast. However, chlorophyll a contents were not different between 23.33 and 17.66 μg/cm2 at exposed- and sheltered-shores of Yellow Coast, and were 9.62 μg/cm2 and 6.80 μg/cm2 on the East Coast. Vegetation indices were positively correlated with chlorophyll a contents. In conclusion, biofilm of Korean upper rocky shore was mainly composed of cyanobacteria and biofilm biomass that differed between the Yellow and East Coast.展开更多
The Castelhano Stream Hydrographic Basin, located in the city of Venancio Aires, RS, Brazil, shows an area of 675.3 km2, highlighting the Castelhano Stream as their main water course. The stream is the main responsibl...The Castelhano Stream Hydrographic Basin, located in the city of Venancio Aires, RS, Brazil, shows an area of 675.3 km2, highlighting the Castelhano Stream as their main water course. The stream is the main responsiblity for the local water supply;however, there are no published studies in the literature regarding their water quality. In this context, the present research aimed to assess the water quality of Castelhano Stream in terms of organic pollution and eutrophication, applying the Biological Water Quality Index (BWQI), which uses epilithic diatoms communities as bioindicators. Biological samples were collected at three sampling stations along the stream in the months of September, November and December 2012. The results showed 81 identified species, distributed in 30 genera. The water pollution levels detected ranged from “strong” (66.7%) and “very strong” (33.3%), with differences in species composition between sampling stations. The sampling station S1 in the upper reaches was characterized by the presence of indicative species of acidophilus and lentic environments with large amounts of organic matter. The sampling stations S2 and S3, in the intermediate and lower reaches, respectively, showed a substitution of species in the community, with the presence of highly tolerant taxa to organic pollution and eutrophication. The high pollution levels detected along the basin are related to the nutrients and high organic load originating from livestock, domestic and industrial waste, as well as excess fertilizers and agricultural inputs used in farming. The results demonstrate the necessity to implement mitigation measures to contain the processes of organic pollution and eutrophication detected due to the dangers offered to public health and the environment.展开更多
In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various resul...In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.展开更多
Simple and inexpensive estimation of the rates and sources of atmospheric nitrogen(N)deposition is critical for its effective mitigation in a region with different land-use types.In this study,the N content and N isot...Simple and inexpensive estimation of the rates and sources of atmospheric nitrogen(N)deposition is critical for its effective mitigation in a region with different land-use types.In this study,the N content and N isotopic composition(δ15N)of moss(Haplocladium microphyllum)tissues and precipitation at six sites with three land-use types(urban,suburban,and rural)were measured in the Yangtze River Delta.A significant linear relationship between moss N content and wet N deposition,and a consistent decrease trend for moss N content and wet N deposition from urban to suburban to rural areas were observed.More negativeδ15N of suburban and rural mosses indicated N mainly released from agriculture and effluent,while the less negativeδ15N of urban mosses were mainly influenced by fossil fuel combustion and traffic emissions.Although the negative mossδ15N indicates that reduced N dominates wet N deposition,there was no significant correlation between mossδ15N and the ratio of ammonium to nitrate(NH4+/NO3−).These results reveal that the moss N content andδ15N can be used as a complementary tool for estimating the rates and sources of wet N deposition in a region with different land-use types.展开更多
Weathering process of rocks in Antarctica can be accelerated by the colonization of lichens, which dominate surface vegetation and endolithic communities respectively in the maritime Antarctic and in Antarctic cold de...Weathering process of rocks in Antarctica can be accelerated by the colonization of lichens, which dominate surface vegetation and endolithic communities respectively in the maritime Antarctic and in Antarctic cold deserts. The effects of lichens on their substrate rocks can be attributed to both physical and chemical causes. As the result of the weathering induced by lichens, the surface corrosion and exfoliation of colonized rocks occur. The mobilization of iron in the rock forming minerals and the precipitation of poorly ordered iron oxides are investigated. Furthermore, the neoformation of crystalline metal oxalates and secondary clay minerals are identified in the colonized rocks. Due to unique climatic conditions, the biotic weathering process of rocks in Antarctica somewhat differs from that of other regions of the world.展开更多
基金Supported by the National Key Technology R&D Program of China(No.2006BAD09A01)the Science and Technology Development Project in Shandong Province(No.2010GHY10505)the Science and Technology Development Project of Yantai(No.2011049)
文摘Periphytic biofilms in aquaculture waters are thought to improve water quality, provide an additional food source, and improve the survival and growth of some reared animals. In the AsiaPacific region, particularly in China, artificial reefs are commonly used in the commercial farming of sea cucumbers. However, few studies have examined the epilithic biofilms on the artificial reefs. To gain a better understanding of the succession of epilithic biofilms and their ecological processes in sea cucumber culture waters, two experiments were conducted in culture waters of the sea cucumber Apostichopus japonicus in Rongcheng, China, using artificial test panels. On the test panels of succession experiment, more than 67 species were identified in the biofilms. On the test panels of seasonal variation experiment, more than 46 species were recorded in the biofilms. In both experiments, communities of epilithic biofilms were dominated by diatoms, green algae and the annelid Spirorbis sp. In the initial colonization, the dominant diatoms were Cocconeis sp., Amphora spp. and Nitzschia closterium in June, which were succeeded by species of Navicula, Cocconeis and Nitzschia(July to September), and then by Licmophora abbreviata, Nitzschia closterium and Synedra spp. in the following months. A diatom bloom in the autumn and filamentous green algae burst in the summer were also observed. Ecological indices well annotated the succession and seasonal changes in epilithic communities. Multidimensional scaling(MDS) analysis found significant differences in diatom community composition among months and seasons. Fast growth of biofilms was observed in the summer and autumn, whereas the biomass of summer biofilms was largely made up of filamentous green algae. Present results show that the components of epilithic biofilms are mostly optimal foods of A. japonicus, suggesting that biofilms on artificial reefs may contribute important nutritional sources for sea cucumbers during their growth seasons. Future works should include quantitative determination of the contribution of epilithic biofilms to the diet of A. japonicus, potential roles of epilithic biofilms in regulating the water quality of sea cucumber ponds, and the regulation of epilithic biofilms in sea cucumber culture ponds.
基金supported by the National Natural Science Foundation of China(Nos.51778603,51820105011 and 51578537)Chinese Academy of Sciences(No.QYZDY SSW-DQC004)。
文摘Virulence factors(VFs)confer upon pathogens the ability to cause various types of damage or diseases.Wastewater treatment plants(WWTPs)are important point sources for the emission of pathogens and VFs into receiving rivers.Conventional WWTP upgrades are often implemented to improve the water quality of receiving ecosystems.However,knowledge on the pathogens,VFs,and health risks to receiving aquatic ecosystems after upgrade remains limited.In this study,we investigated detailed pathogenic information,including taxa,pathogenicity,and health risk,in two wastewater-dominant rivers after WWTP upgrade.Using 16S rRNA gene sequencing,we screened 14 potential pathogens in water and epilithic biofilm samples,though they were significantly more enriched in the biofilms.Combining 16S rRNA and metagenomic sequencing data,we identified Pseudomonas and Aeromonas as the dominant pathogenic taxa carrying functional VFs(e.g.,mobility and offensive)in the epilithic biofilm.Moreover,strong pathogen-specific VF-host co-occurrence events were observed in the epilithic biofilm samples,indicating the importance of biofilms as reservoirs and vehicles for VFs.Further,we demonstrated that mobility VF is crucial for biofilm formation and pathogens in biofilm carrying offensive VF may be highly invasive.Quantification and health risk assessment suggested that the skin contact risk of P.aeruginosa carrying VFs was higher than the acceptable probability of 10^(-4)in both water and epilithic biofilm samples,which may threaten ecological and human health.
文摘Spatial biomass variation and community structure of epilithic biofilms were examined using cell counts, chlorophyll a extraction, and remote-sensing techniques. Samples were collected at two levels of wave exposure along the Yellow and East Coasts of Korea in December 2010. Cyanobacteria were dominant, occupying about 88% of biofilm, irrespective of wave exposure levels. The cyanobacteria species, Aphanotece spp. was abundant in the Yellow Coast location and Lyngbya spp. was abundant in the East coast location. The representative diatoms were Navicula spp. and Achnanthes spp. on the rocky shores of all study sites. Average Normalized Difference Vegetation Index (NDVI) was significantly greater in the Yellow Coast (mean 0.46) than that in the East Coast (mean 0.21);a similar pattern was observed in Vegetation Index (VI). Chlorophyll a content was three times greater on the Yellow Coast (20.50 μg/cm2) than that on the East Coast (8.21 μg/cm2), and it was greater at the Gosapo and Bangpo shore sites than that at the Gyeokpo site, on the Yellow Coast. However, chlorophyll a contents were not different between 23.33 and 17.66 μg/cm2 at exposed- and sheltered-shores of Yellow Coast, and were 9.62 μg/cm2 and 6.80 μg/cm2 on the East Coast. Vegetation indices were positively correlated with chlorophyll a contents. In conclusion, biofilm of Korean upper rocky shore was mainly composed of cyanobacteria and biofilm biomass that differed between the Yellow and East Coast.
文摘The Castelhano Stream Hydrographic Basin, located in the city of Venancio Aires, RS, Brazil, shows an area of 675.3 km2, highlighting the Castelhano Stream as their main water course. The stream is the main responsiblity for the local water supply;however, there are no published studies in the literature regarding their water quality. In this context, the present research aimed to assess the water quality of Castelhano Stream in terms of organic pollution and eutrophication, applying the Biological Water Quality Index (BWQI), which uses epilithic diatoms communities as bioindicators. Biological samples were collected at three sampling stations along the stream in the months of September, November and December 2012. The results showed 81 identified species, distributed in 30 genera. The water pollution levels detected ranged from “strong” (66.7%) and “very strong” (33.3%), with differences in species composition between sampling stations. The sampling station S1 in the upper reaches was characterized by the presence of indicative species of acidophilus and lentic environments with large amounts of organic matter. The sampling stations S2 and S3, in the intermediate and lower reaches, respectively, showed a substitution of species in the community, with the presence of highly tolerant taxa to organic pollution and eutrophication. The high pollution levels detected along the basin are related to the nutrients and high organic load originating from livestock, domestic and industrial waste, as well as excess fertilizers and agricultural inputs used in farming. The results demonstrate the necessity to implement mitigation measures to contain the processes of organic pollution and eutrophication detected due to the dangers offered to public health and the environment.
文摘In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.
基金This study was funded by the National Natural Science Foundation of China[grant numbers 41571324,41673108,41701329,and 41771380]the National Program on Key Basic Research Project(973 Program)[grant number 2014CB953800]+2 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China[grant number 16KJD170001]the Natural Science Foundation of Hainan Province,China[grant number 317190]the CAGS Research Fund[grant numbers YYWF201637,201724].
文摘Simple and inexpensive estimation of the rates and sources of atmospheric nitrogen(N)deposition is critical for its effective mitigation in a region with different land-use types.In this study,the N content and N isotopic composition(δ15N)of moss(Haplocladium microphyllum)tissues and precipitation at six sites with three land-use types(urban,suburban,and rural)were measured in the Yangtze River Delta.A significant linear relationship between moss N content and wet N deposition,and a consistent decrease trend for moss N content and wet N deposition from urban to suburban to rural areas were observed.More negativeδ15N of suburban and rural mosses indicated N mainly released from agriculture and effluent,while the less negativeδ15N of urban mosses were mainly influenced by fossil fuel combustion and traffic emissions.Although the negative mossδ15N indicates that reduced N dominates wet N deposition,there was no significant correlation between mossδ15N and the ratio of ammonium to nitrate(NH4+/NO3−).These results reveal that the moss N content andδ15N can be used as a complementary tool for estimating the rates and sources of wet N deposition in a region with different land-use types.
文摘Weathering process of rocks in Antarctica can be accelerated by the colonization of lichens, which dominate surface vegetation and endolithic communities respectively in the maritime Antarctic and in Antarctic cold deserts. The effects of lichens on their substrate rocks can be attributed to both physical and chemical causes. As the result of the weathering induced by lichens, the surface corrosion and exfoliation of colonized rocks occur. The mobilization of iron in the rock forming minerals and the precipitation of poorly ordered iron oxides are investigated. Furthermore, the neoformation of crystalline metal oxalates and secondary clay minerals are identified in the colonized rocks. Due to unique climatic conditions, the biotic weathering process of rocks in Antarctica somewhat differs from that of other regions of the world.
