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71.
Mucus films, flocs or foams consisting of fine sand, algae and detritus frequently occur in the surface waters of rocky intertidal reef flats during incoming tide. These masses are referred to as mucus aggregates. We examined the developmental process of mucus aggregates and their abundance, distribution, migration and trophic composition. The trophic composition of mucus aggregates was then compared to those of sediments to evaluate their potential nutritional value for benthic animals. The organic matter content, chlorophyll a concentration, microalgal density and bacteria-derived fatty acid contents of mucus aggregates were higher than those observed in sediment, suggesting that mucus aggregates contain not only high levels of organic matter but also dense concentrations of microalgae and bacteria; therefore, mucus aggregates may serve as a qualitatively more energetic food source for benthic fauna compared to sediments. Benthic diatoms were the most abundant organisms in mucus aggregates. Large numbers of diatoms were trapped in fine mineral particles and mucilage-like strings, suggesting that a portion of the mucus is secreted by these benthic microalgae.Mucus aggregate accounted for only 0.01-3.9% of the daily feeding requirements of the dominant detritivore, Ophiocoma scolopendrina (Echinodermata: Ophiuroidea) over the entire sampling area. In contrast, for the species population on the back reef, where mucus aggregates ultimately accumulate, mucus aggregates provided from 0.4 to 113.3% of food for this species. These results suggest that mucus aggregate availability varies spatiotemporally and that they do not always provide adequate food sources for O. scolopendrina populations. 相似文献
72.
1 INTRODUCTION While wastewater discharge regulations have significantly reduced water column pollution, historical and accidental releases of organic pollutants and heavy metals continue to pose an ecological threat as these contaminants have become 搃n-place?sediment pollutants. It had been previously assumed that natural attenuation processes, such as burial or biodegradation, would decrease the contamination levels in surface sediments and, thus, diminish the environmental impact of t… 相似文献
73.
One of the critical technological parameter in operation of aerated submerged fixed‐bed biofilm reactor (ASFBBR) is the control over process of biofilm detachment. Both, an excessive growth of biomass with its accumulation in the bioreactor and an exceeded biofilm detachment rate, cause serious operational and technological problems. The studies presented in this paper demonstrate that in an ASFBBR reactor with a PVC bed carrier media, an effective way to maintain a proper shear stress acting on the biofilm and causing its detachment could be an internal recirculation of wastewater instead of backwashing with wastewater or air flushing. In case of polishing of oil‐refinery wastewater with average COD loading rate equal to 9 g COD/(m2 day), the minimum value of the hydraulic loading rate in such reactor is 1.9 m3/(m2 h), at which there was no excessive growth of biofilms. Despite a significant decrease of the biofilms thickness and amount of biomass in the reactor, there was no significant decline in the efficiency of pollutant removal from oil‐refinery wastewater, which made it possible to obtain the quality of effluent at the outlet of the bioreactor significantly below the water permits and standards. 相似文献
74.
Improving Water Quality by submerged and emergent Macrophytes. — A Review of Ecotechnological Application. Measures of ecotechnology using submerged and emergent macrophytes in native stands or planted littoral stands on the one hand, ingenious swimming plant mats on the other, may be assessed to be successful if applied in combination with additional measures, for instance — reorganization (sanition) of all the area collecting water — biomanipulation of pelagic food chains. Plantation of submerged macrophytes as oxygenators in standing and impounded waters to improve water quality should be avoided. To the contrary, the strategy should be taking measures in order to maximize the light penetrated euphotic zone (zeu) and simultaneously minimize the mixed zone (zmix) in order to improve spontaneous settlements of submerged macrophyte stands. 相似文献
75.
几年来针对巴哈马现代文石鲕粒的持续性研究表明,微生物和细胞外聚合物质(EPS)在鲕粒的形成和发育中起着关键而重要的作用,从而产生了一个重要的认识,即: 鲕粒可以看作是“纹层状的有机沉积构造”并遵循着微生物岩体系的一些形成特征。但是,鲕粒30亿年的发育历史、多样化的产出环境、特征性的矿物构成和各种各样的沉积组构,确实赋予了鲕粒生长和形成机理的复杂性和神秘性,因为鲕粒在何处而且如何形成、以及鲕粒究竟记录着何种生物与非生物过程的许多问题还存在剧烈争论。来自于江苏徐州贾旺剖面苗岭统张夏组上部鲕粒滩相灰岩,由较为典型的方解石放射鲕粒所组成,表现出放射状、放射—同心状和泥晶质的沉积组构,而且在鲕粒核心、鲕粒皮层以及在鲕粒间的不规则团块或凝块的暗色泥晶质构成中高密度地保存着精美的葛万菌(Girvanella)化石,进一步表明了这些暗色泥晶构成代表着较为特征的光合作用生物膜,从而提供了一个苗岭世方解石海中放射鲕粒形成较为直接的微生物证据,以及与光合作用生物膜之间复杂的成因联系,因为葛万菌是相对较为肯定地类比于近代钙化织线菌(Plectonema)的丝状蓝细菌化石,尽管还可类比于现代的伪枝菌(Scytonema)。虽然形成放射状鲕粒皮层的放射纤维状方解石的沉淀作用确实不能解释为直接的微生物沉淀作用的结果,但是,这些放射鲕粒确实表现出光合作用生物膜诱发、滋养并促进了放射纤维状方解石皮层增生作用的重要证据,为拓宽“鲕粒谜”的阐释提供了一个较为重要的典型实例,而且还成为寒武纪苗岭世方解石海与后生动物辐射相耦合的蓝细菌繁荣的重要证据。 相似文献
76.
作为一种以非纹层状组构而区别于叠层石的微生物碳酸盐岩类型,中凝块(mesoclots)是产生凝块石凝块组构关键的微结构。构成这种中凝块的离散性凝块状泥晶,似乎代表了细胞外聚合物质(EPS)复杂的钙化作用,但是,由于常常缺乏直接的微生物证据,造成其所涉及的准确成因和特殊过程还不太清楚。在辽东半岛大连金州湾和本溪田师傅剖面芙蓉统下部的长山组顶部,发育较为典型的凝块石生物丘,组成三级层序的强迫型海退体系域沉积,代表着较为壮观的沉积学现象;在这些凝块石生物丘中,毫米级别大小的暗色离散性凝块状泥晶是其最为基本的沉积组构,而且在这些凝块之中以较高密度保存的丝状蓝细菌鞘化石反映的微生物构成,意味着它们具有明显的光合作用生物膜成因。尽管穿越成岩作用过滤器去解释古代凝块石复杂的形成机理将存在着巨大的挑战,也尽管形成这些凝块石复杂的生物膜钙化作用细节需要更加深入的研究才能得到更好的了解,但是,辽东半岛芙蓉统长山组的凝块石,尤其是在凝块内较为丰富的钙化蓝细菌鞘化石所表征的直接的微生物活动证据,使其成为一个了解光合作用生物膜建造凝块的典型实例;再者,与凝块共生的三叶虫化石、底栖鲕粒和皮壳粒,以及围绕着这些多样化颗粒特别的放射纤维状方解石结壳,说明这些凝块石可能属于较厚的微生物席内多重状生物膜以及构成这些微生物席和微生物膜的细胞外聚合物质复杂的钙化作用建造物。 相似文献
77.
Experimental assessment of Posidonia oceanica‐associated gastropods grazing on an early‐successional biofilm community: nutrient availability and species‐specific effects 
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下载免费PDF全文 Although grazing is considered an essential process controlling epiphyte biomass on seagrass leaves, there is still a lack of fundamental knowledge about the species‐specific consumption rates of the most common grazers in Mediterranean meadows. This study experimentally assessed the effect of Posidonia oceanica‐associated gastropod grazing on early successional biofilm and the species‐specific relationship between biofilm consumption rates and biofilm biomass. Two biofilms on artificial substrata, both developed in situ (in a P. oceanica meadow), one under ambient conditions and the other under nutrient‐enriched conditions, were offered in aquaria assays to nine species of grazers found in P. oceanica meadows. Biofilm consumption rates and their association with biofilm biomass were assessed. It was found that: (i) there was a positive association between biofilm consumption and biofilm biomass up to 20 mg Chl a·m?2 for Bittium reticulatum, Gibbula ardens, Jujubinus exasperatus and Tricolia pullus; (ii) Alvania montagui, B. reticulatum and Jujubinus striatus showed the highest consumption rates and are thus expected to be amongst the leading consumers in early‐successional epiphytic communities; (iii) there was not an increase of consumption rate when a substratum colonized under nutrient‐enriched conditions was offered to any of the nine studied species. This study provides species‐specific consumption rates knowledge that is useful for the assessment of the strength of grazer–epiphyte interactions and trophic fluxes in P. oceanica meadows. 相似文献
78.
Rafael D. Guariento Adriano Caliman Francisco A. Esteves Reinaldo L. Bozelli Alex Enrich-Prast Vinicius F. Farjalla 《Limnologica》2009,39(3):209-218
We performed a field experiment in a tropical humic coastal lagoon to evaluate periphyton biomass accrual and metabolism on three different substrates (1) plastic ribbons, (2) green and (3) senescent leaves of the emergent macrophyte Typha domingensis) over 30 days. The contribution of autotrophic biomass decreased as total biomass increased over the time. Mean periphytic ash free dry weight ranged from 0.8 to 5.6 mg cm−2, but periphyton chlorophyll a concentrations presented shorter amplitudes, which oscillated from 0.12 to 0.44 μg cm−2 throughout the experiment. Periphyton metabolism was overall heterotrophic on all substrates, especially on senescent leaves. Our data show that substrate type influenced both biomass accrual and periphyton net productivity and respiration rates throughout periphyton development and highlighted the dominance of heterotrophic metabolism. The periphyton respiration may be subsidized by both water- and substrate-derived allochthonous energy pathways, shedding light on the role of periphytic assemblages to the carbon cycling, as a source of CO2 to the system. 相似文献
79.
从生物脂类化合物到沉积有机质的变化及其对正演烃源岩有机质形成的启示 总被引：2，自引：2，他引：0
现代海洋生物有机组分的动态变化过程是利用正演法评价海相优质烃源岩的重要中间环节, 可以为估算沉积过程中有机质的损耗提供参考.从化学组成来看, 生物体的脂类与原油成分最为接近, 而且与其他生化组分相比, 脂类的化学性质相对稳定, 可以长期保存在地层中, 因此脂类是最重要的生油母质.温度、盐度、CO2等环境条件以及生物的种类和生长阶段对生物脂类组成有重要影响, 不同环境条件和不同种类的生物对烃源岩有机质的贡献也不同.海水中的有机质在沉积过程中受原始生产力和氧化还原条件的影响.在特定生境中, 在一定的生产力范围内, 沉积有机质的通量与生产力有正相关关系.超过此范围, 沉积有机质通量与生产力关系不大.氧化条件下有机质降解速度快, 而还原条件则有利于沉积有机质的保存.生物膜的形成不仅使有机质更容易沉积, 而且降低了有机质被降解的机会.地质历史时期生物膜的识别对研究烃源岩有机质的保存具有重要意义. 相似文献
80.
通过构建由组合三维电极移动床生物膜反应池、生物膜反应池、臭氧紫外线杀灭微生物池等组成的养殖尾水高效处理系统,应用于工厂化美洲鳗鲡(Anguillarostrata)养殖尾水的集约化高效净水处理,并对系统的排放水循环利用于美洲鳗鲡的精养殖。经140 d的试验应用,结果表明:该系统日平均处理养殖尾水3 000m3,水力停留时间(HRT)为6.2h,经系统处理后的出水总磷浓度为(0.140±0.020) mg/L、总氮浓度为(0.671±0.114) mg/L、氨氮浓度为(0.104±0.050) mg/L、高锰酸盐指数为(2.81±0.44)mg/L,pH为(6.22±0.18)。系统出水水质符合《地表水环境质量标准》(GB3838-2002)的Ⅲ类水。系统出水循环利用于美洲鳗鲡精养殖(处理组)的平均单产55.5 kg/m3,较工厂化美洲鳗鲡养殖模式(对照组)提高52.5%;处理组的结束尾重、存活率、增重倍数和特定生长率分别高于对照组44.9%、5%、64.8%和37.5%,饲料系数低于对照组15.7%。该系统具有水处理效率高、出水水质稳定良好、成本低、节约水资源、环... 相似文献