Microbial Biomass Dynamics Along a Trophic Gradient at the Atlantic Barrier Reef off Belize (Central America)

Abstract. Recent findings indicate that heterotrophic bacteria and not phytoplankton are the most numerous biomass components even in the euphotic zone of oligotrophic, open oceans. In this study it was hypothesized that the microbial biomass components change within a few hundred meters as oligotrophic water flows across the reef and becomes enriched with nutrients. Along a trophic gradient, four stations at the Atlantic Barrier Reef off Belize (Central America) were sampled for microbial biomass components. Phytoplankton biomass (measured as chlorophyll a) ranged from the most oligotrophic station (St. 1) to the most eutrophic station (St. 4) from 6.9–415.5 μg CI"' (assuming a C:chl a ratio of 30): heterotrophic bacterial biomass increased 4-fold (from 10.1–46.4μg C 1^-1), heterotrophic nanoflagellate (HNAN) biomass increased from 4.6-19ug C 1^-1, and cyanobacteria from 0.9-4.5 μg C-1^-1. Production estimates derived from seawater cultures revealed a 5-fold increase in bacterial production from the oligotrophic station (3.7 ug C 1^-1 d^-1) to the eutrophic St. 4 (17.8ug C-1-d1^-1)- Cyanobacterial production rose from 1.1–3.5ug C-1–d^-1 and HNAN production from 0.65-1.13 μg C-1^-1 -d^-1. While cyanobacteria contributed between 13 and 20% to the autotrophic plankton component in the oligotrophic waters, their contribution dropped to about 1 % at the eutrophic stations.     

黄海测区空气微生物含量估计

本文对黄海测区空气微生物作了一次测定 ,结果表明空气中海洋性细菌、真菌的检出率分别为 52 .4 %和 4 7.6 %。陆源性细菌、真菌的检出率分别为80 .0 %和 6 0 .0 %。陆源性微生物出现机率大于海洋性的。空气微生物以细菌为主。测区平均的海洋性空气细菌、真菌、总菌量及真菌 /总菌 %分别为 592 .6 ,32 9.1 ,92 1 .7CFU·m-3 及 35.4。平均的陆源性空气细菌、真菌、总菌量及真菌 /总菌 %分别为 6 89.1、377.9、1 0 6 7.0CFU·m-3 及 35.7。文章分析了空气微生物的时空分布状态。指出测区空气微生物状态反映了海 -气、海 -陆、人和自然的相互作用。     

南极纳尔逊冰川土壤中微生物的群落结构及其代谢特征研究

冰川土壤中的微生物是冰冻圈生态系统中的重要组成部分。南极纳尔逊冰川四周环海,临近海洋的物质输送和其他因素扰动改变了近岸土壤中部分理化因子,从而对土壤中的微生物群落产生影响。本研究采集了南极纳尔逊冰川不同近海距离处的土壤样品,并对其进行了细菌和古菌V4区扩增子测序以及宏基因组测序,探讨了不同近海距离的冰川土壤中的微生物群落结构和代谢潜能。物种多样性结果显示,不同位点的土壤微生物群落组成有所差异,但变形菌门、放线菌门、拟杆菌门等在冰川土壤样品中普遍存在且相对丰度较高。宏基因组分析结果显示,不同近海距离的冰川土壤微生物群落的功能基因分布不同,且能量代谢和跨膜运输等代谢途径的基因的丰度随着采样位点远离海洋而降低。冰川土壤中碳、氮、硫代谢分别以还原性柠檬酸循环、反硝化、同化硫酸盐还原途径为主,其中反硝化途径基因在所有样品中丰度较高。通过分箱组装获得了含有反硝化功能基因的基因组bin＿71,并重构了其核心的代谢通路。本研究初步揭示了南极纳尔逊冰川土壤中微生物的群落结构及代谢潜能,为后续南极冰川土壤新物种的发现、功能基因的挖掘、以及探究全球气候变暖下海洋对沿海生态系统的影响提供了基础数据。     

Faecal indicator bacteria in New Zealand freshwater fish: a pilot study

Recent studies have suggested that poikilothermic animals, such as fish, may represent a previously overlooked source of the faecal indicator bacteria (FIB) used for the assessment of water quality. However, quantitative studies of FIB in poikilotherms are scarce. We investigated the presence of FIB in the faeces of five freshwater fish species. E. coli and enterococci were detected in 71 and 76% of faecal samples, respectively. Concentrations were highly variable, with maximum concentrations (2.1?×?10⁴ E. coli and 1.3?×?10⁶ enterococci per gram of faecal material) up to four orders of magnitude higher than present in the water column. FIB were not detected in faecal samples from marine fish. Our findings suggest that FIB ingested from the environment may be capable of replication within the fish gut, making fish a potential source and transport mechanism for FIB in New Zealand freshwaters. This may have implications for water quality monitoring.     

A case study of sewage discharge in the shallow coastal area of the Northern Adriatic Sea (Gulf of Trieste)

A case study was carried out in 2000 in the shallow coastal area of the Northern Adriatic Sea (Gulf of Trieste) where untreated domestic sewage and industrial wastes are discharged at rate of 5500 m³·day^?1. The sewage plume above the outfall was followed using faecal coliforms (FC) and overturning length scale (l_T). The latter was rejected as a marker as the discharge conditions prohibit following the turbulence of sewage water. Intermittent sewage discharge is reflected in the minimal effect of eutrophication. Increase of phytoplankton biomass is thus only minor compared with the unpolluted area regardless of elevated concentrations of sewage‐derived nutrients (confirmed by correlation coefficients between FC and NH₄⁺, TP, PO₄^3?: 0.78, 0.71 and 0.67, respectively). Deteriorated trophic status, determined by the TRIX index, was observed only in the surface layer (average TRIX: 5.67). High FC content well above the regulation limit (up to 2.6 × 10⁵ FC·100 ml^?1) represents, therefore, the major negative impact of the improperly treated waste for the risk to human health.     

南极中国长城站空气微生物含量监测(英)

The outdoor air borne microbial content over Great Wall Station, Antarctica has been monitored, including its diurnal variations and states in fair or foul weather conditions.The results obtained show: the concentration averaged 161. 9 CFU. m-3. When the weather condition was fair, its range of variation is 0～1 336. 2 CFU. m-3, the average value was 1488. 3 CFU. m-3,when the weather was foul, the range of variation was 471. 4-4 296. 8 CFU. m-3. The average value of air borne microbial number in either fair or foul weather was 383. 0 CFU. m-3. This value is over than 21 times that obtained during 1986/1987.The results seem to show that the influence of human activities have been increasing on Antarctic ecosystem. The diurnal variation of the outdoor air borne microbes shows that the peak of content appeared at about 01: 00, and the trough at about 13: 00 in a whole day. Analyses were made of the relationships between the microbial concentration with its related indexes, i. e. relevant air temperature relative humidity or wind force.The results showed some particularities as compared with those from the areas outside Antarctica.     

Stormflow dynamics and loads of Escherichia coli in a large mixed land use catchment

Storm events are major transporters of faecal microbial contaminants, but few studies have reported storm loads or concentration dynamics in relation to discharge or other pollutants, notably fine sediment. Episodically, high loads of faecal contamination during storm flows impact downstream uses of water bodies, particularly contact recreation and shellfish harvesting. We examined the storm dynamics of Escherichia coli, turbidity and discharge in the mixed land use Motueka catchment (2047 km²; 60% forest and 19% pasture) to gain insights into E. coli sources and transport. We also explored different approaches for calculating E. coli loads. Discharge and field turbidity were recorded continuously, and E. coli concentrations were sampled during events, over a 13‐month period near the mouth of the Motueka River. E. coli loads were estimated by interpolation, averaging estimators and by using linear regression with smearing correction of the log‐transformed variables: discharge, turbidity, and both turbidity and discharge. The annual E. coli load was dominated (～98%) by export during events. Comparison of monthly monitoring with the intensive storm monitoring campaign suggests that simple stratification of the sampling into storm and baseflow would greatly improve export estimates. E. coli peak concentrations always preceded discharge and turbidity peaks (which had similar timing). Turbidity can be a useful surrogate for faecal microbes in smaller catchments, but in the Motueka turbidity was no better for predicting E. coli concentration than discharge. Runoff from grazed pasture and direct deposition from livestock are probably the ultimate E. coli sources in the Motueka catchment. However, in‐channel stores seem to dominate E. coli dynamics during events and account for the typical feature of bacterial concentrations peaking ahead of discharge and turbidity. This study demonstrates the importance of storm events to faecal microbial loads and shows that E. coli concentration dynamics may contrast with those of turbidity. Copyright © 2009 John Wiley & Sons, Ltd.     

北部湾北海─临高海区的空气微生物

对北部湾的北海-临高海区作了空气微生物含量考察。结果表明,测区的空气平均细菌、真菌、总菌量及真菌/总菌的百分比分别为632．3,1324．0,1956．3CFU·m-3及67．7％。数据分析显示：测区空气微生物含量呈北高、南低、中间最少的势态;近岸海区的比相邻陆区的低,海上部分的平均比环海南岛上空的稍大,比粤西海区的稍少。其昼夜变化显示出空气细菌量峰值出现在晨间,谷值在中午。真菌量的峰值出现在黄昏,谷值在上午。其状态基本上不同于北海市区的,但近似于相邻海区的。空气做生物含量与气温间无显著相关关系。结果意味着空气污染近岸区重于海上区,人为活动的影响也较海上区的大。     

Biogenic origin of coastal honeycomb weathering

Honeycomb weathering occurs in two environments in Late Cretaceous and Eocene sandstone outcrops along the coastlines of south‐west Oregon and north‐west Washington, USA, and south‐west British Columbia, Canada. At these sites honeycomb weathering is found on subhorizontal rock surfaces in the intertidal zone, and on steep faces in the salt spray zone above the mean high tide level. In both environments, cavity development is initiated by salt weathering. In the intertidal zone, cavity shapes and sizes are primarily controlled by wetting/drying cycles, and the rate of development greatly diminishes when cavities reach a critical size where the amount of seawater left by receding tides is so great that evaporation no longer produces saturated solutions. Encrustations of algae or barnacles may also inhibit cavity enlargement. In the supratidal spray zone, honeycomb weathering results from a dynamic balance between the corrosive action of salt and the protective effects of endolithic microbes. Subtle environmental shifts may cause honeycomb cavity patterns to continue to develop, to become stable, or to coalesce to produce a barren surface. Cavity patterns produced by complex interactions between inorganic processes and biologic activity provide a geological model of ‘self‐organization’. Surface hardening is not a factor in honeycomb formation at these study sites. Salt weathering in coastal environments is an intermittently active process that requires particular wind and tidal conditions to provide a supply of salt water, and temperature and humidity conditions that cause evaporation. Under these conditions, salt residues may be detectable in honeycomb‐weathered rock, but absent at other times. Honeycomb weathering can form in only a few decades, but erosion rates are retarded in areas of the rock that contain cavity patterns relative to adjacent non‐honeycombed surfaces. Copyright © 2010 John Wiley & Sons, Ltd.