Diversity, biotic and similarity indices: A review with special relevance to aquatic ecosystems

Diversity Indices, Biotic Indices and Similarity Indices are reviewed considering their ecological application, both theoretical and practical. Eighteen diversity indices in eight groups, nineteen biotic indices in ten groups and five similarity indices are examined for their applicability to biological systems, particularly aquatic ecosystems. All the diversity indices were found unsuitable except for Simpsons D, Hurlberts PIE, indices based on the theory of Runs (SCI and TU) and possibly McIntosh's M. Indices based on information theory, such as H′ and H, although the most commonly used diversity indices were unsatisfactory due to the lack of exploration of their biological relevance. The use of H′ in aquatic ecosystems is only justified until the more satisfactory indices are adequately field tested.Biotic indices are highly specialised for a particular type of water pollution, usually organic pollution. Chutter's and Chandler's biotic index appear to be most favoured. In their present form, however, such indices are necessarily limited to the geographical area in which the tolerance lists were compiled. Although many comparisons have been made between diversity indices and biotic indices, these were found to be spurious as one index reflects community structure the other the physiological response of indicator species to one type of pollution. Such comparisons have usually been justified by claiming that one index performs better when compared to the term “water quality”, which is usually left undefined.The five similarity indices examined have been used in aquatic systems. It is not clear which of these indices is best to use. The percentage similarity index (PSC) and Pinkham and Pearson's index (B) appear to be most favoured for aquatic systems, though there is a need for further research and field testing of similarity indices for water pollution.The relationship and definitions of diversity and stability are examined. Though discussion is by no means concluded on this topic it is clear that diversity does not automatically lead to either stability or instability but may be found with both. Disturbance to an ecosystem may often increase diversity provided it is of intermediate frequency, yet an ecosystem may also become more diverse without becoming less stable.The numbers of these three types of indices have become legion, as has their use. It is time that only those indices with biological relevance were used. It is hoped that work will now concentrate on the promising members of the two indices of community structure (diversity and similarity) as these are of broad applicability while biotic indices are limited to one or a few pollutants and one geographical area.     

Assessing the effects of the Prestige oil spill on the European shag (Phalacrocorax aristotelis): trace elements and stable isotopes

The Prestige oil spill resulted in the mortality of several seabird species on the Atlantic NW coast of Spain. Shag casualties were particularly relevant, since populations are resident in the area the whole year round and because of several features which make them highly vulnerable to environmental hazards. Ecological catastrophes give us the opportunity of collecting samples which, otherwise, would be difficult to obtain. We examine the potential of shag corpses as bioindicators of inorganic pollution and the possible factors of variability, such as biological traits (sex, age) or nutrition status. We determined trace elements (Hg, Se, Cr, Pb, Zn and Cu) and isotopic signatures (¹⁵N, ¹³C) in soft tissues (muscle, liver) and in primary feathers formed at different times (before and after the Prestige) in individuals of known sex and age, collected at the time of the Prestige disaster. These were compared with data from another group of shags trapped accidentally in fishing gear in 2005.Our results did not seem to be affected by sex or age on any of the analysed variables. The higher nitrogen isotopic signatures in the soft tissues of the Prestige shags may be related to the nutrition stress caused by a poorer body condition, which is also reflected in increasing levels of some metals in the liver. This isotopic enrichment was also observed in newly forming feathers when compared to the old ones. On the other hand, the lower δ¹⁵N and Hg values in shag feathers from 2005 point to a shift in feeding resources to prey of lower trophic levels. We found that feather features (being an inert tissue and having a conservative composition), if combined with careful dating and chemical analysis, offer a very useful tool to evaluate temporal and spatial changes in seabird ecology in relation to pollution events.     

Water quality and macroinvertebrate community response following pesticide applications in a banana plantation, Limon, Costa Rica

Pesticides used in banana production may enter watercourses and pose ecological risks for aquatic ecosystems. The occurrence and effects of pesticides in a stream draining a banana plantation was evaluated using chemical characterization, toxicity testing and macrobenthic community composition. All nematicides studied were detected in the surface waters of the banana plantation during application periods, with peak concentrations following applications. Toxicity tests were limited to the carbofuran application and no toxicity was observed with the acute tests used. However, since pesticide concentrations were generally below the lowest LC50 value for crustaceans but above calculated aquatic quality criteria, there remains a risk of chronic toxicity. Accurate ecological assessments of pesticide use in banana plantations are currently limited by the lack of local short-term chronic toxicity tests and tests using sensitive native species. Relatively constant levels of four pesticides (imazalil, thiabendazole, chlorpyrifos and propiconazole), which had toxic effects according to the 96h hydra and 21d daphnia chronic test, were recorded in the effluent of the packing plant throughout the study, indicating that the solid waste trap used in this facility was not effective in eliminating toxic chemicals. Certain taxa, such as Heterelmis sp. (Elmidae), Heteragrion sp. (Megapodagrionidae, Odonata), Caenis sp. (Caenidae, Ephemerotera), and Smicridea sp. (Hidropsychidae, Trichoptera), were more abundant at reference sites than in the banana farm waters, and may be good candidates for toxicity testing. Multivariate analyses of the macroinvertebrate communities clearly showed that the banana plantation sites were significantly different from the reference sites. Moreover, following the pesticide applications, all the banana plantation sites showed significant changes in community composition, with the same genera being affected at all sites and for all pesticides (terbufos, cadusafos and carbofuran). Consequently, the results presented here show that multivariate analysis of community composition was more sensitive in distinguishing pesticide effects than the toxicity tests and richness and composition measures used. We conclude that monitoring macroinvertebrate communities can be a powerful tool in the assessment of ecological effects of banana production.     

The effects of a chlorinated discharge and a thermal outfall on the structure and composition of the aquatic macroinvertebrate communities in the sheep river, Alberta, Canada

Physico-chemical and biological samples were collected from 12 sampling stations over a 13-month period to assess the effects of a small town's chlorinated sewage discharge and a thermal discharge on the Sheep River's macroinvertebrate communities. During the study, the chlorinated effluent plume was restricted to the left third of the channel for approx. 0.5 km at which point the effluent was thoroughly mixed due to an abrupt change in channel direction. Within the concentrated 0.5 km chlorinated plume, total residual chlorine TRC concentrations periodically exceeded 5.0 mg l⁻¹. Stations were categorized into similar community assemblages on the basis of species abundance and composition using heirarchical cluster analysis. Stations immediately downstream of the thermal outfall and those within the chlorinated plume had distinctly different structure and were dominated by Oligochaeta. Multiple discriminant analysis indicated that temperature was the principle discriminating variable immediately below the thermal discharge while the chlorinated sewage (MCSE) variable was the most important discriminant function within the chlorinated effluent plume. Following complete mixing of the effluent plume within the stream channel (0.6 km downstream of outfall), macroinvertebrate structure and diversity improved, presumably due to nutrient enrichment and dilution of TRC below detectable levels.     

Diversity and social cohesion: the case of Jane-Finch,a highly diverse lower-income Toronto neighbourhood

Diversity has increasingly emerged as the core focus of many studies concerning factors impacting on social cohesion. Various scholars have concluded that diversity is detrimental to cohesion. Most of this research, however, draws generalisations based upon quantitative data and fails to account for the impact of inequality, segregation and discrimination, and their interconnectedness to diversity. This research provides an in-depth qualitative analysis of the perceptions of inhabitants of a diverse Toronto neighbourhood regarding formal and informal interactions, common values and attachment. The findings suggest that the internalisation of gendered and class-based racism by inhabitants plays a crucial role in shaping perceptions and interactions.     

重庆城市绿地鸟类多样性与影响因素—— 以悦来国际会展城为例

城市绿地能够为城市提供重要的生态系统服务功 能。鸟类作为城市生态系统的重要指示物种,了解影响鸟类群 落多样性的城市绿地特征对于指导城市绿地规划和提升城市生 物多样性有重要意义。然而,多种城市绿地特征如何共同影响 鸟类多样性尚不完全明确。选取重庆市悦来国际会展城为研究 区域,采用样点法调查了49个绿地样地4个季节的鸟类资源数 据,并获取了样地的植被特征、环境特征及人为干扰特征等19 个城市绿地特征。使用广义线性模型、信息论模型选择及差异 性分析方法探析了城市绿地特征对鸟类α多样性的影响,阐述 了研究区鸟类α多样性的基本特征。结果显示：乔木层盖度、 乔木丰富度、灌木层盖度、灌木多度、草本层盖度、草本层多 样性、植被生境类型、环境噪声、距建设用地距离等因素对鸟 类α多样性有显著影响。鸟类α多样性特征在不同植被生境类 型及季节之间存在显著差异。麻竹生境的鸟类多度显著低于其 余多种生境,冬季鸟类α多样性指标偏低。在城市绿地的建设 中,根据显著影响鸟类的各种城市绿地特征,提出增强鸟类α 多样性的针对性建议,如控制乔木盖度,补充灌木层,以乡土 食源树种作为植被生境中的优势种,对冬季休眠植被进行分区 保留管理等。研究结果可以为地区城市生物多样性保护及城市 生态系统优化提供重要参考。     

Responses of aquatic organisms to metal pollution in a lowland river in Flanders: a comparison of diatoms and macroinvertebrates

The role of macroinvertebrates and diatoms as indicator for metal pollution was investigated by assessing both biota along a metal gradient in the Belgian river the Dommel. Macroinvertebrates and diatoms were sampled in summer and winter and physical-chemical characteristics of the water were measured at four different sample periods and related to sediment characteristics. Although metal concentrations, except cadmium, in the water nowhere exceeded water quality standards, high metal concentrations were measured in the sediment, indicating historical contamination of the Dommel. At the sites that were situated downstream of the pollution source, high levels of conductivity and chloride were measured in the water. Redundancy Analysis (RDA) indicated pH, phosphate and zinc as the significant environmental variables explaining each respectively 7.7%, 11.6% and 22.6% of the macroinvertebrate community composition. Two clusters could be separated, with Gammarus pulex, Leptocerus interruptus, Baetis rhodani and Cloeon dipterum associated with low zinc concentrations and Tubificidae, Asellus aquaticus, Erpobdella sp. and Chironomus thummi-plumosus associated with higher zinc concentrations. Ammonium (10.6%), conductivity (16.5%), chloride (11.4%) and zinc (5.9%) turned out to be significant variables explaining the diatom community structure. Based on physical-chemical differences and species composition, three different groups could be separated. With this Tabellaria flocculosa and Fragilaria capucina var. rumpens were associated with low metal concentrations, Gomphonema parvulum and Nitzschia palea with elevated concentrations and Eolimna minima and Sellaphora seminulum with high zinc concentrations. In conclusion, the diatom community best reflected the metal gradient. With regard to water quality indices, those based on macroinvertebrates best followed the metal pollution gradient and were most strongly correlated with physical-chemical variables of water and sediment. This study indicated that to assess the effect of metal pollution in lowland rivers, the combined use of macroinvertebrates and diatoms is more appropriate than the use of both biota separately.     

Anaerobic treatment of municipal wastewater at ambient temperature: Analysis of archaeal community structure and recovery of dissolved methane

Anaerobic treatment is an attractive option for the biological treatment of municipal wastewater. In this study, municipal wastewater was anaerobically treated with a bench-scale upflow anaerobic sludge blanket (UASB) reactor at temperatures from 6 to 31 °C for 18 months to investigate total chemical oxygen demand (COD) removal efficiency, archaeal community structure, and dissolved methane (D-CH₄) recovery efficiency. The COD removal efficiency was more than 50% in summer and below 40% in winter with no evolution of biogas. Analysis of the archaeal community structures of the granular sludge from the UASB using 16S rRNA gene-cloning indicated that after microorganisms had adapted to low temperatures, the archaeal community had a lower diversity and the relative abundance of acetoclastic methanogens decreased together with an increase in hydrogenotrophic methanogens. D-CH₄, which was detected in the UASB effluent throughout the operation, could be collected with a degassing membrane. The ratio of the collection to recovery rates was 60% in summer and 100% in winter. For anaerobic treatment of municipal wastewater at lower temperatures, hydrogenotrophic methanogens play an important role in COD removal and D-CH₄ can be collected to reduce greenhouse gas emissions and avoid wastage of energy resources.     

Assessing productivity changes in water companies: a comparison of the Luenberger and Luenberger-Hicks-Moorsteen productivity indicators

ABSTRACT

Interest in evaluating productivity changes in water companies has increased in recent years. In this paper, for the first time, we employ the Luenberger-Hicks-Moorsteen Productivity Indicator (LHMPI) to evaluate productivity changes in a sample of Chilean water companies from 2010 to 2016. Productivity change estimations obtained by both the Luenberger Productivity Indicator (LPI) and the LHMPI are compared. Moreover, both indicators were computed assuming constant and variable returns to scale technologies. The LHMPI estimates illustrate that productivity in Chilean water companies has slightly improved over the period studied due to the positive trend of outputs, whereas the inputs negatively contributed to productivity changes. Results from the empirical analysis enabled us to verify that the LHMPI and LPI (and their drivers) are statistically different. This conclusion illustrates that water regulators need to pay attention to the indicators used when assessing productivity changes in water companies.     

DNA-based stable isotope probing: a link between community structure and function

DNA-based molecular techniques permit the comprehensive determination of microbial diversity but generally do not reveal the relationship between the identity and the function of microorganisms. The first direct molecular technique to enable the linkage of phylogeny with function is DNA-based stable isotope probing (DNA-SIP). Applying this method first helped describe the utilization of simple compounds, such as methane, methanol or glucose and has since been used to detect microbial communities active in the utilization of a wide variety of compounds, including various xenobiotics. The principle of the method lies in providing ¹³C-labeled substrate to a microbial community and subsequent analyses of the ¹³C-DNA isolated from the community. Isopycnic centrifugation permits separating ¹³C-labeled DNA of organisms that utilized the substrate from ¹²C-DNA of the inactive majority. As the whole metagenome of active populations is isolated, its follow-up analysis provides successful taxonomic identification as well as the potential for functional gene analyses. Because of its power, DNA-SIP has become one of the leading techniques of microbial ecology research. But from other point of view, it is a labor-intensive method that requires careful attention to detail during each experimental step in order to avoid misinterpretation of results.     

Control-oriented model of a solar community with seasonal thermal energy storage: development,calibration and validation

The development of a control-oriented model of a solar community with seasonal storage (the Drake Landing Solar Community) is investigated. The proposed approach, intended to facilitate the development and testing of control strategies and targeting an actual predictive control implementation, is based on grey-box models, and enables the prediction of the system state (temperatures at key locations). This paper discusses the concept of state update procedure (whereby the system state is periodically corrected with measurements), which plays a fundamental role for control purposes. Firstly, the DLSC is presented and both operation and monitoring system are described. Secondly, a simplified model is developed for each sub-system: district and solar loops, short-term (water tanks) and seasonal (borehole) thermal energy storage, and existing operation rules are encoded. Finally, the model is calibrated and validated by using measurements at 10-min intervals over two years of operation (2015–2016, 2016–2017) and accurately predicts the system performance.