Using multiple indicators to evaluate the ecological integrity of a coastal plain stream system

We demonstrate the use of multiple indicators to characterize the ecological integrity of a coastal plain stream system in the New Jersey Pinelands in relation to human-induced watershed alterations. The individual indicators include pH, specific conductance, stream vegetation and stream-fish, impoundment-fish, and anuran assemblages. We evaluate and compare the utility of the individual and multiple environmental and biological indicators and present a relatively straightforward method for ranking sites. Specific conductance and pH measured at 88 monitoring sites varied in relation to the percentage of altered land (developed land and upland agriculture) within the associated watersheds. All three environmental variables were associated with variations in the composition of stream vegetation and stream fish, impoundment fish, and anuran assemblages. With the exception of impoundment fish, the association between altered land and the multiple-indicator scores based on the two water-quality indicators and the four biological indicators was stronger than that displayed by any of the individual variables.     

Aligning indicators of community composition and biogeochemical function in stream monitoring and ecological assessments

Reliable and inexpensive indicators of ecosystem function are essential for accurately monitoring and describing ecosystem integrity. Currently, most state and federal assessments of aquatic ecological integrity rely on structural indicators and assume tight coupling of structure and function. We used fluorescent composition of dissolved organic matter as a metric for certain ecosystem functions and compared the resulting index of autochthonous microbial dissolved organic matter (DOM) to macroinvertebrate indicators and classifications of water quality attainment reported by the Maine Department of Environmental Protection (Maine DEP) at 142 stream sites. We observed that metrics of sensitive insect orders such as relative Plecoptera generic richness, relative Ephemeroptera abundance, and generic richness of EPT (Ephemeroptera, Plecoptera, and Trichoptera) were negatively correlated with higher values of metrics based on autochthonous microbial DOM sources. At the same time we observed an increase in the Hilsenhoff Biotic Index with increasing microbial DOM. We compared the abundance of this microbial DOM component to Maine DEP measured attainment classes and found that microbial DOM generally separated sites with high biological integrity from sites where the biotic community was highly degraded. This highlights that measures of biogeochemical ecosystem function complement measures of structure in biological assessments.     

Quantifying relationships between land‐use gradients and structural and functional indicators of stream ecological integrity

1. Modification of natural landscapes and land‐use intensification are global phenomena that can result in a range of differing pressures on lotic ecosystems. We analysed national‐scale databases to quantify the relationship between three land uses (indigenous vegetation, urbanisation and agriculture) and indicators of stream ecological integrity. Boosted regression tree modelling was used to test the response of 14 indicators belonging to four groups – water quality (at 578 sites), benthic invertebrates (at 2666 sites), fish (at 6858 sites) and ecosystem processes (at 156 sites). Our aims were to characterise the ecological response curves of selected functional and structural metrics in relation to three land uses, examine the environmental moderators of these relationships and quantify the relative utility of metrics as indicators of stream ecological integrity. 2. The strongest indicators of land‐use effects were nitrate + nitrite, delta‐15 nitrogen value (δ¹⁵N) of primary consumers and the Macroinvertebrate Community Index (a biotic index of organic pollution), while the weakest overall indicators were gross primary productivity, benthic invertebrate richness and fish richness. All indicators declined in response to removal of indigenous vegetation and urbanisation, while variable responses to agricultural intensity were observed for some indicators. 3. The response curves for several indicators suggested distinct thresholds in response to urbanisation and agriculture, specifically at 10% impervious cover and at 0.1 g m^?3 nitrogen concentration, respectively. 4. Water quality and ecosystem process indicators were influenced by a combination of temperature, slope and flow variables, whereas for macroinvertebrate indicators, catchment rainfall, segment slope and temperature were significant environmental predictor variables. Downstream variables (e.g. distance to the coast) were significant in explaining residual variation in fish indicators, not surprisingly given the preponderance of diadromous fish species in New Zealand waterways. The inclusion of continuous environmental variables used to develop a stream typology improved model performance more than the inclusion of stream type alone. 5. Our results reaffirm the importance of accounting for underlying spatial variation in the environment when quantifying relationships between land use and the ecological integrity of streams. Of distinctive interest, however, were the contrasting and complementary responses of different indicators of stream integrity to land use, suggesting that multiple indicators are required to identify land‐use impact thresholds, develop environmental standards and assign ecological scores for reporting purposes.     

A stressed stream ecosystem: macroinvertebrate community integrity and microbial trophic response

A year-long study of a second-order stream in Southwestern Virginia was carried out from 1979–80. One of the objectives of the study was to evaluate the effects of sewage and electroplating plant effluent stress on the trophic response of aquatic invertebrate assemblages and microbial communities in the stream. Quantitative benthic samples were collected periodically at three reference stations and four stressed stations below the outfalls. Invertebrates were counted, identified taxonomically, and classified into functional groups based on their feeding strategies. Ash-free dry weights were obtained for each functional group by date and station, and the number and density of different taxa were calculated as well. Reference stations had diverse invertebrate assemblages; scrapers were well represented and all functional groups were present in reasonably equivalent proportions. Stressed stations were dominated by collector gatherers and filterers to the virtual exclusion of scrapers. The trophic status of the microbial community was determined by suspending artificial substrates in the stream for 1-week periods. The community that colonized the substrates was assayed for ATP and chlorophyll a, and an autotrophy index (AI) was calculated using these values. The autotrophic component of the microbial community was greatest at the reference stations, and the community became primarily heterotrophic below the outfalls. The AI correlated well with the proportion of scrapers. Aquatic invertebrate assemblages and microbial communities responded to stress by changing their trophic structure to fit best the available energy sources. Where heterotrophic microbes dominated, gathering and filtering invertebrates utilized the abundant organic matter. In areas where a mainly autotrophic microbial community existed, scrapers, gatherers, and filterers were all present in balanced proportions.     

The development of appropriate ecological criteria and indicators for community forest conservation using participatory methods: A case study in northeastern Thailand

The paper reports the development and evaluation of relevant local ecological criteria and indicators for participatory resource management of community forest. The study site, the Nong Meg-Nong Hee community forest, Maha Sarakham Province, is in northeastern Thailand. Multi-criteria decision-making (MCDM) was adopted as a decision-making tool to evaluate criteria and indicators, using coarse and fine screening, based on local community participation. The criteria and indicators set consisted of 3 principles, 7 criteria, and 41 indicators covering the main attributes of forest ecosystem conservation. Relevant data were processed in a hierarchical framework and used as a template for further assessment, i.e., Principle 1 (forest ecosystem structure and composition), Principle 2 (forest ecosystem function), and Principle 3 (disturbance signs). The two selection phases comprised (1) the coarse screening based on scoring and ranking, and (2) fine screening, using a pair-wise comparison analysis to classify the order of relative weights of the indicators (importance value) and the consistency index (CI) of each criterion. As a result of coarse screening one criterion and 16 indicators were eliminated from the analysis, while the remaining 3 principles, 6 criteria, and 25 indicators were retained for fine screening. Most criteria showed an acceptance value of less than 10% (tolerance consistency index threshold level). The final set of criteria and indicators, based on locally understandable ecological concepts of forest conservation, was ranked in order of importance under each criterion and applied to the study area. We conclude that these techniques are appropriate for selecting criteria and indicators, as they are relatively transparent, understandable and offer an input to participatory decision-making.     

A comparison of bacterial,ciliate and macroinvertebrate indicators of stream ecological health

We evaluate the reliability of communities of bacteria and ciliated protozoa as indicators of freshwater ecological health. Samples of epilithic biofilm were taken from 18 freshwater streams, impacted by varying types and degrees of catchment modification. Communities of bacteria and ciliates were characterised using DNA fingerprinting techniques (automated ribosomal intergenic spacer analysis and terminal restriction fragment length polymorphism, respectively) and macroinvertebrate data also obtained, for comparison. Similar to the macroinvertebrates, the taxa richness of ciliate communities was reduced in more developed stream catchments; significant differences in the evenness of ciliate communities were also detected. We could identify no significant relationship between the richness of bacterial taxa and the percentage catchment development. However, a significant trend was detected between bacterial community structure and the predominant catchment land use (rural vs. urban) using a Bray–Curtis measure of similarity, a relationship not detected for the ciliate and macroinvertebrate communities. These findings indicate that stream bacterial, ciliate and macroinvertebrate communities each respond differently to various catchment conditions and highlight the potential of microbial communities to provide novel, alternative indicators of stream ecosystem health.     

Diatoms are better indicators of urban stream conditions: A case study in Beijing,China

Urbanization dramatically affects hydrology, water quality and aquatic ecosystem composition. Here we characterized changes in diatom assemblages along an urban-to-rural gradient to assess impacts of urbanization on stream conditions in Beijing, China. Diatoms, water chemistry, and physical variables were measured at 22 urban (6 in upstream and 16 in downstream) and 7 rural reference stream sites during July and August of 2013. One-way ANOVA showed that water physical and chemical variables were significantly different (p < 0.05) between urban downstream and both reference and urban upstream sites, but not between reference and urban upstream sites (p > 0.05). Similarly, structural metrics, including species richness (S), Shannon diversity (H′), species evenness (J′) and Simpson diversity (D′), were significantly different (p < 0.05) between urban downstream and both reference and urban upstream sites, but not (p > 0.05) between reference and urban upstream sites. However, diatom assemblages were very different among all sites. Achnanthidium minutissima was a consistent dominant species in reference sites; Staurosira construens var. venter and Pseudostaurosira brevistriata were the dominant species in urban upstream sites; and Nitzschia palea was the dominant species in urban downstream sites. Clustering analyses based on the relative abundance of diatom species, showed all the samples fit into three groups: reference sites, urban upstream sites, and urban downstream sites. Canonical correspondence analysis (CCA) and Monte Carlo permutation tests showed that concentration of K⁺, EC, TN, Cl⁻ and pH were positively correlated with relative abundance of dominant diatom species in urban downstream samples; WT and F⁻ were correlated with reference and urban stream diatom composition. Our results demonstrate that the composition of diatom species was more sensitive to urbanization than the water physical and chemical parameters, and that diatom assemblage structure metrics more accurately assessed water quality. Some species, such as Amphora pediculus and Cocconeis placentula were among the dominant species in low nutrients stream sites; however, they were considered to be high nutrient indicators in some streams in USA. We suggest using caution in applying indicator indices based on species composition from other regions. It is necessary to build a complete set of diatom species data and their co-ordinate environment data for specific regions.     

Patterns of abundance and morphology as indicators of ecosystem status: A meta-analysis

A series of studies have suggested that abundance and morphology distributions approximate the lognormal in undisturbed communities and depart from the lognormal with disturbance. However, this proposed capability to indicate ecosystem status has been challenged on theoretical, methodological and statistical grounds. This paper quantifies the departure from the lognormal in natural communities, and the sensitivity of such departures to disturbance, species richness, sample size, temporal and spatial scale, taxa, methodological protocols and other confounding factors. We have conducted a rigorous test of the hypothesis that distance to the lognormal represents a powerful indicator of ecosystem status. We tested three measures of distance to the lognormal and their sensitivity by reviewing 38 case studies and simulated community patterns and examined the potential and pitfalls of the approach. The most robust parameter for measuring the departure from the lognormal was found to be the normalized distance to the lognormal (ΔL). ΔL proved to be a reliable and adaptable indicator of disturbance, which is effective over a broad range of biological systems (terrestrial and aquatic, most taxa, social and economic). We show that ΔL can be measured either by quantifying abundance or by organism size, a cheaper and easy to obtain metric. Abundance distributions provide an indication of system status on a shorter time scale than size distribution. Taken together, they provide clues to the direction in which the system is moving. The sensitivity analysis shows which methods will lead to consistent results across disciplines. Our simulations confirm that disturbance consistently pushes complex systems away from the lognormal pattern, as suggested by empirical data. We conclude that the departure from the lognormal can be used as an indicator of status of a dynamic ecosystem as long as appropriate procedures are followed. Systems approximating the lognormal (ΔL close to 0) can usually be considered self-organized and little disturbed by external influences.     

Identifying the scales of variability in stream macroinvertebrate abundance, functional composition and assemblage structure

1. Many natural ecosystems are heterogeneous at scales ranging from microhabitats to landscapes. Running waters are no exception in this regard, and their environmental heterogeneity is reflected in the distribution and abundance of stream organisms across multiple spatial scales. 2. We studied patchiness in benthic macroinvertebrate abundance and functional feeding group (FFG) composition at three spatial scales in a boreal river system. Our sampling design incorporated a set of fully nested scales, with three tributaries, two stream sections (orders) within each tributary, three riffles within each section and ten benthic samples in each riffle. 3. According to nested anova s, most of the variation in total macroinvertebrate abundance, abundances of FFGs, and number of taxa was accounted for by the among‐riffle and among‐sample scales. Such small‐scale variability reflected similar patterns of variation in in‐stream variables (moss cover, particle size, current velocity and depth). Scraper abundance, however, varied most at the scale of stream sections, probably mirroring variation in canopy cover. 4. Tributaries and stream sections within tributaries differed significantly in the structure and FFG composition of the macroinvertebrate assemblages. Furthermore, riffles in headwater (second order) sections were more variable than those in higher order (third order) sections. 5. Stream biomonitoring programs should consider this kind of scale‐dependent variability in assemblage characteristics because: (i) small‐scale variability in abundance suggests that a few replicate samples are not enough to capture macroinvertebrate assemblage variability present at a site, and (ii) riffles from the same stream may support widely differing benthic assemblages.     

A suite of ecological indicators for evaluating the integrity of structural eco-complexity in Mexican forests

This paper presents a conceptual framework for analyzing forest complexity as the combination of the variety of species and key structures that are associated with the composition, structure, and function of forest stands. Several spatial indicators have been developed to characterize the biodiversity, the structural complexity, and anthropogenic effects that can be observed in Mexican forests. By integrating several stand complexity attributes, the forest condition can be characterized as a function of species composition, stand structural attributes, and forest development. In addition, indicators of anthropogenic effects were also analyzed to identify their influence on forest eco-complexity, and therefore, on the current condition of forests. The results of applying this conceptual framework showed that Mexican forest are ecologically complex, with varying levels of anthropogenic impacts that modify the structural forest characteristics, particularly in tropical forests. The main factor explaining the current eco-complexity condition in tropical forests was associated with early stages of forest development, due to ecological degradation, and showed a generalized loss of attributes, particularly for stand complexity and stand development. In contrast, temperate forests exhibited better eco-complexity conditions, especially for those attributes that define forest stand occupancy and development. Mining activities, forest extraction as selective harvesting, forest fires, land use change, and road openings are critical human activities that directly affect forest structure and, ultimately, modify forest eco-complexity and integrity. This eco-complexity index derived for Mexican forests can be used to integrate measures of forest structure and functioning, and thereby better inform decision making and policy development.     

Nation-wide indicators of ecological integrity in Mexico: The status of mammalian apex-predators and their habitat

Ecological indicators that evaluate the status and trends of mammalian apex predators are necessary for monitoring the ecological integrity of landscapes. Several nation-wide spatial indicators that describe the status of apex predators after habitat transformation have been developed for México. These spatial indicators show the condition of the remnant natural landscape for maintaining the complexity of predator-prey interactions and habitat selection and use. The indicators were obtained using the concept of ecological integrity, that characterize the landscape based upon manifest and latent variables of naturalness, stability and self-organization, according with the measures of spatial distribution of species and natural habitat. When the current status is evaluated for individual species of apex predators, all species showed less than 50% of their distribution areas with a high degree of ecological integrity. Neotropical predators (such as jaguars and ocelots) are more threatened by the transformation of natural habitat, than their counterparts in Nearctic regions (e.g., bears, cougars, bobcats, and coyotes), which showed nonetheless, a high amount of their distribution areas with a high proportion of degraded habitat. The indicators allowed evaluating the status of still extant top predators in the landscape and their habitat condition within major ecoregions in the country.     

The influence of stream sediment particle size on bacterial abundance and community composition

Sediment features may play a major role in determining benthic bacterial community structure. In this study, sediment samples were collected on four dates over the course of a year from a Northeast Ohio stream and fractionated into different particle size classes. Abundance of bacteria of various taxa on differentially sized sediment fractions was determined using fluorescent in situ hybridization which relies on taxon-specific oligonucleotide probes that hybridize to rRNA in intact cells. The differences among the size classes were generally small in comparison to the large seasonal changes observed. These seasonal changes differed greatly among taxa; for some, peaks in the number of cells hybridizing a particular probe were in the spring (Domain Bacteria, α-Proteobacteria), while others peaked in the summer/fall (γ-Proteobacteria and the Cytophaga-Flavobacterium). At the species level, the abundances of Burkholderia cepacia and Acinetobacter calcoaceticus were highest in the summer on sediments of all sizes. Seasonal differences appeared to be more of a factor driving community differences than sediment particle size.     

Quantifying the ecological stability of a phytoplankton community: The Lake Kinneret case study

The widely used term “stability” has multiple meanings and is rarely quantified in limnological studies. The main objective of this study was to develop an approach for quantifying the stability of a phytoplankton community using Lake Kinneret as a case study. It is a first attempt of calculating an index of stability for each of the five main taxonomic groups of the Kinneret phytoplankton (Bacillariophyta, Chlorophyta, Cryptophyta, Cyanophyta and Dinophyta), and for the entire community. A simple statistical approach to calculate the stability index was devised, using phytoplankton wet-weight biomass as the parameter being manipulated. The period 1970–1979 was selected as a reference period. The following stability indices were established and applied (each at three time scales): (1) a stability index for each of five main taxonomic groups; (2) a combined index of the stability, aggregating the stabilities of the individual taxonomic groups and (3) a stability index of entire community based on total phytoplankton biomass. The dynamics of these indices during 1969–2011 were examined. Destabilization of the community structure was triggered by an increase in the variability of Bacillariophyta biomass shortly after the reference period, in 1981–1983. Only 10 years later, the community destabilization become associated with progressively increasing biomass of Cyanobacteria. Dinophyta were the last to destabilize in the mid 1990s. Despite notable changes in the community structure, the total phytoplankton biomass remained relatively stable. Therefore, in 1969–2011 the stability index based on total phytoplankton biomass was higher than the combined index based on the stabilities of the individual taxonomic groups. Only weak relationships were found between the stability index values and potential driving forces (lake water level fluctuations and nutrient loads). While this approach was applied to Lake Kinneret, the concept presented is not lake specific and could be applied to other lakes.     

Historic log structures as ecological archives: A case study from eastern North America

Forests of eastern North America have undergone abrupt transformations over the last several centuries due to changing land use and climate. Researchers look to pre-settlement forests as a guide for forest restoration, though much of our understanding of composition and dynamics in pre-settlement forests is based on spatially restricted sediment records, few and fragmented old-growth stands in a narrow range of site types, and potentially biased historical documentation. Logs from historic structures hold information that may be useful to forest ecology in eastern North America, but before these records can be used, we must first establish where the logs originated, why they were selected over other trees, and what they can and cannot tell us about past forest ecology. Using a case study approach, I collected data from fifteen log structures in the central Appalachian region to compare construction site locations, species used, and mean diameter of logs through time to determine the ecological biases associated with human behavior in log structure construction. Construction site locations changed from valleys to mountains through time and the species used in construction shifted from Quercus alba to a mix of Quercus alba, Liriodendron tulipifera, Pinus strobus, and Castanea dentata over time. The diameter of logs used in construction were generally consistent through time, with an average basal diameter of 31.3 cm (±4.7). Mean age of logs increased through time for Quercus species, regardless of log diameter. These results suggest the species used for structural logs were selected by their abundance at the location of construction but that as construction site locations and resource availability changed through time, the species used in construction changed as well. While there are biases and limitations of dendroecological data from historic structures, the results presented here demonstrate that structural log data provide greater replication during the early European immigration period, representation of upland (valley) forest sites, and establishment of chronologies for species that are not well represented in current tree-ring chronologies (e.g. Castanea dentata, Liriodendron tulipifera). These results suggest structural logs can benefit ecological research by filling the temporal, spatial, and species gaps in tree-ring chronologies not only for the central Appalachian region, but also for other areas in eastern North America.     

A case study: fecal corticosteroid and behavior as indicators of welfare during relocation of an Asian elephant

This study was a preliminary investigation of an enzyme immunoassay for measuring fecal glucocorticoid metabolites in a male Asian elephant (Elephas maximus) by investigating changes in behavior and cortisol metabolite excretion associated with a putative stressful event. The study collected fecal samples for 10 days prior to, and 10 days after, 24-hr transport and relocation of the elephant to a new herd. The study measured cortisol metabolites using 2 enzyme immunoassays indicating a 389% and 340% increase in cortisol metabolite excretion following relocation. Maximal cortisol metabolite excretion occurred 2 days after relocation and remained elevated during establishment of the new herd. Stereotypic behavior increased approximately 400% after relocation. The relocation disturbed sleep patterns, the elephant spent less time sleeping during the night, and the elephant slept standing up. These results provide preliminary evidence that noninvasive monitoring of fecal cortisol metabolites can be used to investigate adrenal activity in Asian elephants and may be a safe, practical, and accurate welfare indicator.     

生态系统完整性内涵及评价方法研究综述

生态系统完整性是资源管理和环境保护中一个重要的概念.它主要反映生态系统在外来干扰下维持自然状态、稳定性和自组织能力的程度.评价生态系统完整性对于保护敏感自然生态系统免受人类干扰的影响有着重要的意义.耗散结构理论表明,外界压力和反映系统自组织能力的生物、物理、化学完整性和生态系统功能等对生态系统的完整性有良好的指示作用.本文综述了水生生态系统和陆地生态系统完整性及其所承受的压力评价指标,并探讨了优先评价指标的筛选及综合评价方法,最后根据存在的一些问题提出今后的研究展望.     

生态修复措施对流域生态系统服务功能的提升——以潮河流域为例

流域生态环境修复工程对保护和提高流域生态系统服务功能及其价值起到了至关重要的作用。本文基于InVEST模型,选取密云水库上游,潮河流域为研究对象,依据各地区"十三五"生态环境保护规划中针对潮河流域的生态修复措施,设置化肥减量、河岸缓冲带、退耕还林和综合修复四种情景,并采用直接市场法和替代市场法研究生态系统服务价值的变化。经过研究发现:①四种情景都有效的提高了生态服务功能和价值;②单独实施化肥农药减量,不能显著降低TP(-13.14%)、TN(-10.94%)负荷;③采取综合修复的方式能使潮河流域水源涵养,TP、TN拦截,土壤保持能力分别提高了40.18%、53.89%、42.32%以及63.76%,同时生态服务价值增加7.73×10⁷元。这一发现旨在通过对不同生态修复措施在生态环境修复中的成本与效益分析,帮助决策者和规划单位准确评估生态修复的收益,从而制定提高生态环境系统服务功能的最佳修复方案。     

Diversity,occurrence and feeding traits of caddisfly larvae as indicators for ecological integrity of river-floodplain habitats along a connectivity gradient

In order to assess ecological values of Lower Rhine and Meuse floodplain habitats we studied the spatial and seasonal variation in diversity, species assemblages and feeding traits of caddisfly larvae in water bodies over the lateral connectivity gradient: eupotamon: main and secondary channels; parapotamon: channels connected permanently with the main channel only at their downstream ends; plesiopotamon: disconnected channels close to the main channel; paleopotamon: abandoned meanders at a greater distance from the main channel.Spatial variety was studied by analyzing the summer species composition in 70 Lower Rhine and Meuse water bodies which were categorized in connectivity habitats, whereas seasonal variety was studied in Lower Rhine water bodies along a connectivity gradient by monthly sampling over a whole year. Physico-chemical data and environmental parameters were recorded for each water body during sampling. Diversity and species assemblages of caddisfly larvae varied in relation to connectivity, macrophyte diversity and abundance and stream velocity. A comparison with historical records and species lists from less disturbed rivers showed that diversity in the main channel was very low.Caddisfly larvae species assemblages varied over the connectivity gradient. Lotic habitats (eupotamon) were separated from the lentic ones, and the well vegetated paleopotamon from the sparsely vegetated parapotamon and pleisopotamon habitats, indicating the overall importance of vegetation and current velocity for the species assemblages. Hydropsychidae have been found in the eupotamon exclusively, whereas Limnephilidae, Hydroptilidae and Polycentropodidae have been found predominantly in the paleopotamon water bodies. Leptoceridae were found in all floodplain water body categories. A similar pattern of distribution of families along the lateral connectivity gradient was found in more natural rivers.Caddisfly larvae species feeding traits showed a clear differentiation over the lateral connectivity gradient with filter-feeders and scrapers most important in the eupotamon and parapotamon, and shredders, piercers and predators most dominant in the paleopotamon habitats, indicating the importance of nutritional resources in relation to hydrological connectivity for the structure and functioning of caddisfly larvae species assemblages. The analysis of the species feeding traits allows generalizations towards the entire aquatic community and general prognoses for other floodplain ecosystems.