A Conceptual Framework for Using Mussels as Biomonitors in Whole Effluent Toxicity

As a main source of direct and continuous input of pollutants in the aquatic ecosystem, studying the effects of effluents on receiving ecosystems has a high ecological relevance. While ecological risk assessment procedures are usually based on a chemical-based single component approach, their application for complex mixtures and effluents is less straightforward. A chemical-based approach has to rely on the knowledge of what chemicals are present in effluents, their potential toxicity, how all of these individual chemicals interact and what their individual and combined contribution to the mixture is. Whole effluent toxicity (WET) testing, however, is an integrative tool that measures the toxic effect of an effluent as a whole and accounts for uncharacterized sources of toxicity and for interactions. This paper addresses the use of transplanted bivalves, i.e., caged mussels, as a biomonitoring tool in WET testing with special reference to field situations in both freshwater and marine environments. We indicate how endpoints at different levels of biological organization within exposed mussels can give an integrative overview of effects. Finally, we will provide a framework for future research using mussels and discuss a multitude of instream responses for routine, efficient and cost-effective active biomonitoring applications.     

Structural and functional aspects of treated mine water and aquaculture effluent streams

Multiple effluent streams may flow into a single receiving stream making it difficult to understand the effects of a single effluent source or the interactions between effluents. In this study, we examined benthic community structure and function in an effluent stream formed by the release of treated mine water, in treated mine water that had been used as a water source for flow-through aquaculture and below the confluence of the two. This study demonstrated that macroinvertebrate communities, while taxonomically simple, developed in treated mine water. The addition of aquaculture effluent to the treated mine water allowed colonization by additional taxa, increased leaf decomposition rates and may have conferred resistance to a turbidity event. Ecosystem responses were mediated by the surrounding terrestrial environment. In shaded conditions macroinvertebrate densities could be as much as 10× higher and the taxa were dominated by simuliids and chironomids, while in open conditions filamentous algae flourished and the taxa were dominated by hydroptilids and chironomids. Consequently, consideration of stream processes that promote preferred ecological processes, such as macroinvertebrate production and organic matter processing, when siting effluent streams may reduce impacts on receiving streams.     

Phytoplankton recovery responses at the population and community levels in a hazard and risk assessment study

Both structural and functional relationships were investigated in experiments using S. capricornutum populations and an indigenous microbial community. Our aims were to diagnose cellular stress and to predict recovery during exposures to a chlor-alkali effluent.Laboratory experiments demonstrated that the effluent was toxic at concentrations greater or equal to 4%, v/v. It appears that during the exposure period, the functional parameters, particularly the intracellular adenylates ratios were reliable in predicting algal population recovery.On the other hand, the river gradient experiments failed to demonstrate a toxic effect on community structure over the time scale studied. Functional parameters revealed a significant effect on photosynthetic activity while adenylate energy charge was an insensitive indicator.Finally, our results tend to demonstrate that functional responses, particularly intracellular adenylates ratios (ATP/cell; ATP/AMP) are appropriate to predict recovery responses to a toxicant at the population and community levels. This would prove useful in enhancing the ecological significance of toxicity tests in hazard assessment.     

THE USE OF TOXICITY TESTING IN EFFLUENT REGULATION AND CONTROL: A NEW DIMENSION TO ASSESSMENT AND MANAGEMENT OF WATER QUALITY IN SOUTH AFRICA

Summary

Efficient management tools are continually required to cope with increasing demands placed on the quality and quantity of aquatic resources. Recent developments in environmental monitoring indicate the importance of incorporating biological indicators in assessment programmes. Aquatic toxicology has consequently become an important monitoring and regulatory science. Applications of aquatic toxicity testing include: deriving water quality criteria; toxicological evaluations of whole effluents and receiving waters; and the estimation of ecological risk. Toxicity testing can potentially play a significant role in improving water quality in years to come, especially through its application in effluent regulation. Currently however, few environmental laboratories in South Africa have the required expertise and facilities to carry out a representative range of toxicity tests. Training and funding are required to build the capacity for the necessary developmental research, before toxicity testing can routinely be implemented.

The significant problems we face cannot be solved at the same level of thinking we were at when we created them. Albert Einstein.     

Toxicity evaluation of parboiled rice effluent using sperm quality of zebrafish as bioindicator

This study aimed to assess the acute toxicity of raw and treated wastewater generated by the rice parboiling industry using zebrafish (Danio rerio) sperm quality as a bioindicator. Toxicity bioassays were conducted comparing physicochemical parameters of sperm quality for zebrafish at sublethal conditions (n = 150 fish, 50 per treatment). Acute toxicity was detected in all sperm quality parameters assessed for both raw and treated wastewater, when contrasted to the control (p < 0.05). For zebrafish exposed to raw effluent, negative correlations with parameters of sperm quality were observed for the concentration of iron, phosphorus and total suspended solids (p < 0.05). Salinity, the biochemical oxygen demand and the concentration of total suspended solids were negatively correlated with parameters of sperm quality for zebrafish exposed to treated effluent (p < 0.05). In comparison with the levels observed for the raw effluent, most physicochemical parameters of the treated effluent were reduced to levels within the limits required by the environmental legislation. Despite the physical and chemical parameters measured in the treated wastewater meeting environmental legislation thresholds, acute toxicity persisted. These results show that the sperm quality can be used as a bioindicator for wastewater toxicity and release of wastewater to surface water could affect the fertility of fishes.     

Investigation of the sublethal effects of some petroleum refinery effluents

In Canada, environmental regulations for protection of the biota from the adverse effects of effluents from petroleum refineries have tended to focus on acute toxicity. There is concern those effluents may have other subtle, but still deleterious, long-term effects on aquatic ecosystems. We have used a battery of toxicity tests to assess the acute toxicity, genotoxicity, and chronic toxicity of effluent samples from two Ontario refineries. The test organisms included representatives of the bacterial, algal, plant, cladoceran, and fish communities. The results of our preliminary study indicate that the effluent samples had little acute toxicity to the test organisms. There were indications of some sublethal toxicity to Ceriodaphnia dubia, Panagrellus redivivus, and Pimephales promelas. One of the effluents inhibited the growth of Selanastrum capricornutum (IC₅₀ of 59.9%) and Lemna gibba (IC₂₅ of 73.3%) and also caused a 15 percent reduction in the germination of Lactuca sativa seeds. The SOS-Chromotest, a commercially available test that measures the activity of a bacterial DNA repair system, detected genotoxic effects in a single effluent that had been concentrated ten fold. There was no apparent relationship between several chemical parameters and the observed sublethal effects. Further research is needed to establish whether or not the observed toxic effects are typical of effluents from Ontario refineries.     

Implementation of a multiple biomonitoring approach to evaluate the potential for impact from an industrial discharge

Over a 2-year period, an industrial discharger implemented a program to determine if there was a potential for in-stream impact from its discharge, and, if necessary, to eliminate that potential. Six basic study designs were used. These included: (1) ambient toxicity tests using indicator organisms; (2) in-stream waste concentration (IWC) chronic testing using indicator organisms; (3) on-site flow-through toxicity testing using indicator and resident species with receiving stream water as the diluent; (4) in situ acute toxicity studies using indicator and resident species; (5) biological surveys of the receiving stream; and (6) artificial stream studies. The outcome of the studies resulted in conclusive data on which to base the design of a diffuser to dilute the effluent 1:20. This concentration was well below the lowest acute no-observed-effect concentration (10% effluent) determined using sensitive resident test species. In this manner, impact from the effluent on the James River had been reduced so that even the most sensitive resident species were protected. As a result of the study, the facility's permit was modified so that toxicity tests were made only on effluent diluted with receiving stream water to represent dilution at 1Q10 rather than 100 percent effluent. Follow-up studies have concentrated on a series of toxicity tests which were designed to identify the toxicants in the final effluent.     

以毒性鉴别评价法评价化工废水处理效果的研究

江苏省某化工厂废水处理设施进、出水经大型Sou（Daphnia magna）急性毒性试验的结果表明,废水在处理前、后均显示毒性。采用毒性鉴别评价的试验程序,对处理设施的进、出水进行了关键毒物的鉴别和评价。发现进水中存在的关键毒物为金属铜离子并共存多种金属和极性有机毒物,而出水中存在的毒物为酸性条件下易被氧化的有毒有机物。该废水处理工艺对废水毒性去除率为77.6%。由此可见,该处理工艺对金属离子有较好的去除,而对有毒有机化合物的去除效果不甚理想,因此,该厂生产工艺和废水处理工艺还有待进一步改进。     

The effects of low concentrations of particulates from paper mill effluent on the macroinvertebrate community of a fast-flowing stream

The effects of a paper mill effluent on the macroinvertebrate community were assessed for the riffle areas of a large fast-flowing stream, the lower reaches of the Saranac River of northern New York State, U.S.A. The effluent caused few changes in dissolved oxygen concentration, pH, biochemical oxygen demand, temperature or nutrient content; however, significant differences in transmitted light, concentrations of particulates and accumulated debris on the substrate were observed. A moderate decrease in invertebrate diversity correlated with increased levels of particulates and substrate debris. An analysis of the response of invertebrate functional groups revealed the effluent had little effect on the density of gathering collector organisms. The functional groups most severely reduced in density were the filtering collectors and scrapers. Predators showed a moderate reduction in density in response to the effluent. The alterations in invertebrate densities were attributed largely to the alterations in seston and substrate caused by the introduction of particulates composed mainly of paper fiber and inert dye.     

The Lab-to-Field (LTF) Rating Scheme: A New Method of Investigating the Relationships between Laboratory Sublethal Toxicity Tests and Field Measurements in Environmental Effects Monitoring Studies

The Lab-to-Field (LTF) rating scheme is a straightforward method of relating the results of effluent toxicity tests to the field survey measurements and has proven to be a useful tool for interpretation of Environmental Effects Monitoring studies for pulp and paper mills in the province of Ontario. The LTF method uses the same five-level scale (level 1 for no or low response to level 5 for severe response) for rating the toxicity and field survey results. Regression analysis of LTF scores has revealed that the relationship between the Ceriodaphnia reproduction test and benthic invertebrate field survey measurements was significant (p < 0.001, r = 0.79). However, there were not sufficient data to determine if this can be used as a predictive tool. Nonetheless, Ceriodaphnia-to-benthic survey, Selenastrum-to-benthic survey and fathead-to-fish survey relationships were qualitatively rated strong or moderately strong in 94%, 75%, and 60% of the 16 studies, respectively. The LTF rating scheme would benefit from the use of a more sensitive species or life stage of fish to strengthen the sublethal test-to-fish survey relationship. Further validation of the lab-to-field relationship could be accomplished through the synoptic collection of effluent samples for sublethal tests and field measurements.     

Acute toxicity testing with the European estuarine amphipod <Emphasis Type="Italic">Corophium multisetosum</Emphasis>

This study reports on the use of the estuarine amphipod Corophium multisetosum in acute toxicity testing. The species was successfully acclimated to the laboratory and was used in a water-only whole effluent 96 h acute bioassay and in a 10 days whole estuarine sediment test. C. multisetosum response was compared to other species in 96 h bioassays, testing boiling cork effluent and iron filings lixiviates. The amphipod showed high sensitivity and the results were similar to those obtained with others species namely, the freshwater cladoceran Daphnia magna, the estuarine amphipod Gammarus chevreuxi and the seawater annelid Sabellaria alveolata. In a 10 days static exposure to natural impacted estuarine sediments, the response of the species was compared to a fertilization bioassay with the sea-urchin Paracentrotus lividus. Both species indicated the same sediment samples as the most potentially toxic. These samples were collected in sites where the resident macrofauna benthic community is also the most affected, with strong reduction of the species richness, abundance and biomass. The results revealed that C. multisetosum presents high potential to be used in routine acute toxicity testing in the estuarine environment.     

Development of hormosira banksii (PHAEOPHYCEAE) embryos in selected components of secondarily-treated sewage effluent

We investigated the effects of phosphate, ammonium, and a mixture of heavy metals as components of sewage effluent, together with the effects of reduced salinity due to sewage effluent discharge into a marine environment, on the development of Hormosira banksii (Turner) Decaisne embryos. The concentration of each effluent component tested in this study was calculated to approximate levels in the shore zone where H. banksii once occurred at Boags Rocks (Victoria, Australia) and the artificial sea medium was diluted to 20‰ S based on average salinity levels measured at this site. Newly fertilized eggs were cultured in each of these components and combinations of components for up to 7 days. Ammonium, elevated to levels that occur in the vicinity of the outfall, and fresh water, which reduces seawater salinity, were the most damaging of the effluent components tested. Osmotically stressed embryos commonly showed swollen chloroplasts, loss of cell contents, vesiculate cytoplasm, and stunted rhizoid development. Exposure to elevated levels of ammonium retarded embryo development and growth until day 7, when cellular damage became evident. The number of damaged embryos was significantly greater when exposed to elevated levels of ammonium added to artificial seawater medium diluted to 20‰ S. The adverse effects caused by elevated levels of ammonium and reduced seawater salinity on H. banksii embryo development could have contributed to the disappearance of this species from Boags Rocks.     

Bacterial community shift revealed Chromatiaceae and Alcaligenaceae as potential bioindicators in the receiving river due to palm oil mill effluent final discharge

A thorough outlook on the effect of palm oil mill effluent (POME) final discharge towards bacterial community dynamics in the receiving river is provided in this study by using a high-throughput MiSeq. The shift of bacterial composition could be used to determine the potential bacterial indicators to indicate contamination caused by POME. This study showed that the POME final discharge did not only alter the natural physicochemical properties of the river water but also caused the reduction of bacterial diversity in the receiving river. The Chromatiaceae and Alcaligenaceae which were not detected in the upstream but were detected in the downstream part of the river are proposed as the indicator bacteria to indicate the river water contamination caused by POME final discharge. The emergence of either one or both bacteria in the downstream part of the river were shown to be carried over by the effluent. Therefore, an accurate pollution monitoring approach using bacterial indicator is expected to complement the conventional POME pollution assessment method which is currently dependent on the physicochemical properties of the final discharge. This is the first study that reported on the potential indicator bacteria for the assessment of river water contamination caused by POME final discharge.     

The application of bioassay techniques to water pollution problems — The United Kingdom experience

The quality of the aquatic environment has long been assessed by chemical analyses and by biological surveillance of plant and animal communities. More recently, the biological response of living organisms has been used to evaluate the environmental impact of aqueous wastes.Laboratory tests on single species have been used widely to evaluate the acute effects of potential pollutants. However, the value of such tests, often conducted on exotic species, is receiving increasing criticism. Measurements of more subtle chronic sub-lethal effects are now showing increasing promise as regulatory tools in environmental assessment and pollution control. The paper reviews the techniques being used, and those currently under development for, the water pollution control authorities in the UK. Practical examples of applications are provided and the future value of bioassays is discussed.     

Single cell protein from pineapple cannery effluent

Candida utilis was grown on pineapple cannery effluent as the sole carbon and energy source. These effluents are rich in microbially utilizable nutrients. The principal sugars in the effluent were glucose, fructose and sucrose, and when supplemented with diammonium hydrogen phosphate to prevent nitrogen limitation they supported good growth. The maximum specific growth rate (m=0.46h–1) and cell yield coefficient (Yc/s=0.30) were obtained with 23.2 g carbohydrate/l in the growth medium. The values of m and Yc/s varied with carbohydrate concentration: higher values of m and Yc/s were obtained with lower concentrations of carbohydrate, suggesting that a chemostat would be more suitable for single cell protein production. Freeze-dried yeast contained 55.3, 51.2, 1.45, 6.4 and 27.4% of crude protein, true protein, DNA, RNA and carbohydrate respectively. The yeast had a balanced amino acid profile, except for sulphur-containing amino acids. A 90–95% reduction in the chemical oxygen demand of the effluent was achieved during this process which suggests that yeast may be effectively used to treat this waste.     

Toxicity of high salinity tannery wastewater and effects on constructed wetland plants

The toxicity of high salinity tannery wastewater produced after an activated sludge secondary treatment on the germination and seedling growth of Trifolium pratense, a species used as indicator in toxicity tests, was evaluated. Growth was inhibited by wastewater concentrations >25% and undiluted effluent caused a complete germination inhibition. Constructed wetlands (CWs) with Arundo donax or Sarcocornia fruticosa were envisaged to further polish this wastewater. Selection of plant species to use in CWs for industrial wastewater treatment is an important issue, since for a successful establishment they have to tolerate the often harsh wastewater composition. For that, the effects of this wastewater on the growth of Arundo and Sarcocornia were assessed in pot assays. Plants were subject to different wastewater contents (0/50/100%), and both were resilient to the imposed conditions. Arundo had higher growth rates and biomass than Sarcocornia and may therefore be the preferred species for use in CWs treating tannery wastewater. CWs planted with the above mentioned plants significantly decreased the toxicity of the wastewater, as effluent from the CWs outlet stimulated the growth of Trifolium at concentrations <50%, and seed germination and growth even occurred in undiluted effluent.     

Measuring the impact of sewage effluent on the macroinvertebrate community of an upland stream: The effect of different levels of taxonomic resolution and quantification

Abstract Benthic macroinvertebrates were sampled from four sites on upland streams in the Wentworth Falls area of the Blue Mountains, NSW. One site received effluent from a sewage treatment plant and the others were reference sites. Five replicate collections were taken from each site on four occasions at intervals of 3 months. Macroinvertebrate community data were analysed using univariate (ANOVA) and multivariate (NMDS) techniques and comparisons were made between analyses at different levels of taxonomic aggregation and using different methods of data transformation. Similar patterns were observed at both species and family levels, and even the order level showed a clear community response to effluent input. Binary (presence/ absence) data provided similar results to quantitative data for the species and family levels. However, when binary data were used at the order level, the distinctions between the reference sites became blurred. We discuss the implications of these findings for environmental monitoring.     

Assessing measurable adverse changes to benthic invertebrate communities based on site-specific sediment toxicity testing and community data at the Anniston,Alabama PCB site

Laboratory toxicity tests were conducted for polychlorinated biphenyl (PCB)-containing sediment from Choccolocco Creek at the Anniston PCB Site. The objective of this investigation was to develop a site-specific PCB concentration–response relationship for invertebrate test organisms. Test results from reference locations were used to develop background-adjusted 10% (EC10*) and 20% (EC20*) effect concentrations for a range of survival, growth, and reproduction endpoints. The EC20* values ranged from 4.43 to 114 milligrams of PCBs per kilogram (mg/kg) of sediment on a dry weight basis for reproductive endpoints, 28 to 67.7 mg/kg sediment for growth, and 123 to 165 mg/kg sediment for survival. The aggregate EC20* response range for endpoints that demonstrated good test performance with reasonable ranges in control variability (<20%) and reference sample responses was 14.3 to 165 mg/kg. The PCB concentrations in sediments for a majority of the Site rarely exceed even the lowest of these thresholds. Given the protective process used to develop these thresholds, there is a high level of confidence that benthic communities are not impacted. This finding is supported by direct measurements of the benthic communities that have been living and reproducing on the Site.     

Modified Whole Effluent Toxicity Test to Assess and Decouple Wastewater Effects from Environmental Gradients

Environmental gradients and wastewater discharges produce aggregated effects on marine populations, obscuring the detection of human impact. Classical assessment methods do not include environmental effects in toxicity tests designs, which could lead to incorrect conclusions. We proposed a modified Whole Effluent Toxicity test (mWET) that includes environmental gradients in addition to effluent dilutions, together with the application of Generalized Linear Mixed Models (GLMM) to assess and decouple those effects. We tested this approach, analyzing the lethal effects of wastewater on a marine sandy beach bivalve affected by an artificial canal freshwater discharge used for rice crops irrigation. To this end, we compared bivalve mortality between canal water dilutions (CWd) and salinity controls (SC: without canal water). CWd were prepared by diluting the water effluent (sampled during the pesticide application period) with artificial marine water. The salinity gradient was included in the design by achieving the same final salinities in both CWd and SC, allowing us to account for the effects of salinity by including this variable as a random factor in the GLMM. Our approach detected significantly higher mortalities in CWd, indicating potential toxic effects of the effluent discharge. mWET represents an improvement over the internationally standardized WET tests, since it considers environmental variability and uses appropriate statistical analyses.     

Performance and microbial diversity of palm oil mill effluent microbial fuel cell

Aim: To evaluate the bioenergy generation and the microbial community structure from palm oil mill effluent using microbial fuel cell. Methods and Results: Microbial fuel cells enriched with palm oil mill effluent (POME) were employed to harvest bioenergy from both artificial wastewater containing acetate and complex POME. The microbial fuel cell (MFC) showed maximum power density of 3004 mW m^?2 after continuous feeding with artificial wastewater containing acetate substrate. Subsequent replacement of the acetate substrate with complex substrate of POME recorded maximum power density of 622 mW m^?2. Based on 16S rDNA analyses, relatively higher abundance of Deltaproteobacteria (88·5%) was detected in the MFCs fed with acetate artificial wastewater as compared to POME. Meanwhile, members of Gammaproteobacteria, Epsilonproteobacteria and Betaproteobacteria codominated the microbial consortium of the MFC fed with POME with 21, 20 and 18·5% abundances, respectively. Conclusions: Enriched electrochemically active bacteria originated from POME demonstrated potential to generate bioenergy from both acetate and complex POME substrates. Further improvements including the development of MFC systems that are able to utilize both fermentative and nonfermentative substrates in POME are needed to maximize the bioenergy generation. Significance and Impact of the Study: A better understanding of microbial structure is critical for bioenergy generation from POME using MFC. Data obtained in this study improve our understanding of microbial community structure in conversion of POME to electricity.