Phytoplankton as biomonitors: A study of Museum Lake in Government Botanical Garden and Museum,Thiruvananthapuram, Kerala India

An assessment of the pollution status of Museum Lake in the Thiruvananthapuram Botanical Garden and Museum was conducted. Analysis of different community structures of the planktonic taxa in the lake revealed it is organically polluted, attributable to the organic litter from riparian vegetation. A total of 30 most pollution‐tolerant phytoplankton genera and 24 pollution‐tolerant species were identified. Pollution‐tolerant phytoplankton genera in the lake included Chlorophyceae, Bacillariophyceae, Cyanophyceae and Euglenophyceae. Scenedesmus, Pinnularia, Euglena, Ankistrodesmus, Closterium, Crucigenia, Kirchneriella, Merismopedia and Oscillatoria were some of the phytoplankton pollution tolerant genera whereas, Nitzschia palea, Synedra acus, Scenedesmus quadricauda, Pandorina morum and Trachelomonas volvocina were some of the pollution tolerant species noted. Excessive nutrient loading from the surrounding area is definitely degrading the quality of this urban lake ecosystem. Detailed information regarding the pollution status of a waterbody is very important in this regard, noting it ultimately assists in undertaking proper management of a waterbody. The Palmer Algal Index score for Museum Lake was 37, indicating it is highly organic enriched. The results of different algal indices (e.g. Chlorophycean Index; Nygaard Index) indicated a eutrophic condition for Museum Lake, being attributed to its increased organic enrichment. Canonical correspondence analysis between environmental variables and the microalgal bioindicators also highlighted the influence of the physical and chemical parameters on phytoplankton abundance and distribution in Museum Lake.     

DISTRIBUTION AND ABUNDANCE OF STREAM FISHES IN RELATION TO BARRIERS: IMPLICATIONS FOR MONITORING STREAM RECOVERY AFTER BARRIER REMOVAL

Dams are ubiquitous in coastal regions and have altered stream habitats and the distribution and abundance of stream fishes in those habitats by disrupting hydrology, temperature regime and habitat connectivity. Dam removal is a common restoration tool, but often the response of the fish assemblage is not monitored rigorously. Sedgeunkedunk Stream, a small tributary to the Penobscot River (Maine, USA), has been the focus of a restoration effort that includes the removal of two low‐head dams. In this study, we quantified fish assemblage metrics along a longitudinal gradient in Sedgeunkedunk Stream and also in a nearby reference stream. By establishing pre‐removal baseline conditions and associated variability and the conditions and variability immediately following removal, we can characterize future changes in the system associated with dam removal. Over 2 years prior to dam removal, species richness and abundance in Sedgeunkedunk Stream were highest downstream of the lowest dam, lowest immediately upstream of that dam and intermediate farther upstream; patterns were similar in the reference stream. Although seasonal and annual variation in metrics within each site was substantial, the overall upstream‐to‐downstream pattern along the stream gradient was remarkably consistent prior to dam removal. Immediately after dam removal, we saw significant decreases in richness and abundance downstream of the former dam site and a corresponding increase in fish abundance upstream of the former dam site. No such changes occurred in reference sites. Our results show that by quantifying baseline conditions in a small stream before restoration, the effects of stream restoration efforts on fish assemblages can be monitored successfully. These data set the stage for the long‐term assessment of Sedgeunkedunk Stream and provide a simple methodology for assessment in other restoration projects. Copyright © 2011 John Wiley & Sons, Ltd.     

Real-time biomonitoring of water contamination by cyanide based on analysis of the continuous electric signal emitted by a tropical fish: Apteronotus albifrons

A new early warning system for monitoring the quality of water was developed using the information conveyed by the continuous electric organ discharges of the tropical fish Apteronotus albifrons (Gymnotiformes, family Apteronotidae). The principle is based on the time characterisation of the electric signal emitted by the fish and uses the fact that the frequency and the form of the signal vary as a function of the physico-chemical quality of the ambient water. Eight test fish were individually confined in a heat-proof test chamber in which a continuous water current, thermo-regulated at 27°C, was maintained. The electric signal sampled over 1 s periods were amplified. The computer processed the signals and their frequencies and determined the coordinates of the points where the temperatures were recorded. The results of the A. albifrons electrical activity were then visualised on a visual display unit. Subsequent mathematical processing helped to detect unusual electrical behaviour (crossing of lower and upper bounds). To illustrate the principle of this new early warning system, the electric response of the A. albifrons exposed to cyanide was tested and compared with the detection thresholds of other biological early warning systems. A. albifrons is able to detect a cyanide concentration of 34.6 μg l⁻¹ in less than half an hour. The recorded results suggest that this new biomonitor corresponds very well with the requirements of warning stations for surface waters subject to cyanide pollution.     

SPATIAL VARIATION OF STRUCTURAL AND FUNCTIONAL INDICATORS IN A LARGE NEW ZEALAND RIVER

The ecological responses of large rivers to human pressure can be assessed at multiple scales using a variety of indicators, but little is known about how the responses of ecological indicators vary over small spatial scales. We sampled phytoplankton, zooplankton and macroinvertebrates and measured river metabolism and cotton strip breakdown rates (loss in tensile strength) in contrasting habitats along a 21‐km urban‐industrial reach on a constrained section of the Waikato River, New Zealand's longest river. Rates of gross primary production (2.8–7.8 g O₂/m²/d) and ecosystem respiration (3.5–12.7 g O₂/m²/d) did not differ consistently between near‐shore (2–3 m from river side) and far‐shore (ca. 10 m from side) locations, urban and industrial reaches or between autumn and spring sampling occasions. Rates of cotton decay (?k) ranged from 0.014 to 0.112 per day and were typically faster at far‐shore locations and in the section of river receiving industrial inputs, but slower in spring compared with autumn. Nonmetric multidimensional scaling analysis of phytoplankton and zooplankton data did not reveal spatial patterns relating to pressure or location (embayment, edge, mid‐river). However, the macroinvertebrate ordination suggested distinct communities for the mid‐river benthos compared with near‐shore communities and a distinction between sites in the urban reach and the industrial reach. Our results suggest that large‐river macroinvertebrate communities and cotton decay rates can be influenced to varying degrees by reach‐scale pressures and local habitat conditions. Monitoring designs in spatially complex rivers should account for habitat heterogeneity that can lead to differences in structural and functional indicator responses. Copyright © 2012 John Wiley & Sons, Ltd.     

Fingerprinting Chamaesiphon populations as an approach to assess the quality of running waters

Cyanobacterial communities are highly diverse in freshwaters and respond rapidly to changing environments. Previous studies have highlighted variations in the structure and composition of epilithic cyanobacterial communities in response to eutrophication in watercourses. In the present study, changes in benthic cyanobacterial communities from Guadalix River (Spain) biofilms were examined using temperature‐gradient gel electrophoresis (TGGE) in conjunction with microscopic examination of field‐fixed samples, focusing on populations of one of the dominant cyanobacteria: Chamaesiphon. Environmental characteristics were determined in order to characterize the trophic status of the sampling sites. The presence of cyanobacteria in the river was determined from complex TGGE patterns, band extraction, and subsequent sequencing of 16S rDNA gene fragments. The microscopic observations revealed that the unicellular genus Chamaesiphon and the filamentous genus Phormidium were dominant in the studied locations. Within the 2 genera, 4 Chamaesiphon populations were identified (Chamaesiphon fuscus, Chamaesiphon starmachii, Chamaesiphon subglobosus, and Chamaesiphon polymorphus) and Phormidium was represented at the sampling sites by the Phormidium autumnale morphotype. TGGE banding patterns differed among samplings sites as a function of water quality. The genetic analysis revealed 4 phylotypes within the genus Chamaesiphon and 1 phylotype within the classic P. autumnale clade. Chamaesiphon phylotypes were not equally distributed in all the sampling locations. Some phylotypes were related to low nutrient concentrations, while others were associated with eutrophic conditions. Our results support the use of fingerprints of Chamaesiphon populations obtained by TGGE to examine changes in water quality.     

AP-PCR Fingerprinting for Detection of Genetic Damage Caused by Polycyclic Aromatic Hydrocarbons

Exposure of organisms to genotoxic chemicals results in the formation of stable, covalently bound adducts between the chemical (or one of its metabolites) and the DNA, these adducts may cause mutations and cytogenetic changes. The primary effects of such exposure (i.e. adduct formation) and subsequent effects on the DNA (cytogenetic damage, mutation) may be monitored using a number of assays of varying sensitivity and specificity. Recent developments in molecular biology offer new possibilities for detecting DNA damage. We examined whether DNA fingerprinting by arbitrarily primed polymerase chain reaction (AP-PCR) can reveal differences in the DNA fingerprints of rats and shore crabs exposed to benzo[a]pyrene in the laboratory and of crabs from control and from polluted areas. The results indicate that differences between control and exposed animals were detectable and that DNA fingerprinting by AP-PCR offers a useful alternative biomarker assay for the detection of the genotoxic effects of environmental pollutants.     

生物标志物监测环境污染研究新进展

生物标志物在环境污染监测方面的应用日益重要,文章侧重于对生物标志物在此方面的应用进行全面阐述,包括:生物标志物的定义及分类,生物标志物的特征及优势,生物标志物在检测环境污染的应用,最后还提出了生物标志物在环境监测方向的展望。     

MONITORING POLYCYCLIC AROMATIC COMPOUNDS IN ENVIRONMENTAL AND WORKPLACE SAMPLES USING CONVENTIONAL METHODS AND THE AMES MUTAGENICITY ASSAY OF THEIR NITRATED DERIVATIVES

The development of sensitive methods for monitoring polycyclic aromatic compounds (PACs) has been a central focus of industrial hygiene studies in those industries where workers are exposed to petroleum oils, bitumen fumes or fuel combustion products. The work reported here focuses on one aspect of that effort—workplace monitoring of airborne PAC levels in the hot-mix asphalt paving industry. During the manufacture, transport, and roadway application of hot-mix asphalt (HMA), workers are exposed to low levels of bitumen fumes emanating from the hot product. Over the last twenty-five years, concerns about the health effects of these exposures have prompted numerous studies of the airborne levels of asphalt fumes in the workplace. By and large, these studies have shown that PAC exposures are extremely low—often below the detection limits of standard analytical techniques. For the present study, we have used standard industrial hygiene methods, together with a newer, biologically based assay called the Nitration Assay to measure relative ambient levels of fumes and/or PACs in various paving workplace settings. The latter assay was also used to test bitumen fumes generated in the laboratory by a new “microfuming” technique and to determine specific activities of the 16 PAHs designated by the US EPA as priority pollutants. The Nitration Assay takes advantage of two properties of 3–7-ring PACs: the ease with which they can be chemically nitrated and the high mutagenic potency of the nitrated products in the Ames Salmonella mutagenicity assay. Measurements of fumes and nitratable PAC levels on seven different hot-mix paving jobs showed reasonable correlations between the various methods, as well as patterns of exposure consistent with proximity to fume source.