Status assessment in acid-sensitive and non-acid-sensitive Maryland coastal planin streams using an integrated biological,chemical, physical,and land-use approach

This study was designed to: (1) evaluate the ecological status of acid-sensitive and non acid-sensitive Maryland coastal plain streams using biological (Index of biotic Integrity [IBI] for fish), chemical and physical habitat conditions; (2) determine if a low IBI for coastal plain stream fish can be related to stream sensitivity from acidic inputs and (3) correlate land use activities and watershed size in the coastal plain streams with biological, chemical and physical conditions. IBI values obtained using 12 community metrics for Maryland coastal plain stream fish demonstrated that there were no significant differences in these values when acid-sensitive and non-acid-sensitive streams were compared. However, other complementary data in acid-sensitive streams such as absence of the acid-sensitive species, blacknose dace and higher numbers and biomass of tolerant species suggested that these streams may be impacted. IBI values were also found to be negatively correlated with various trace metals in acid-sensitive streams but not in non-acid-sensitive areas. Chemical conditions such as trace metals and nutrients were associated with land use activities. Highest concentrations of trace metals (chromium, nickel, and cadmium) were found in streams with the highest percentage of low residential housing. Nitrate concentrations were significantly higher in streams found in agricultural areas than in forested areas. Agriculturally dominated streams with highest nitrate concentrations (> 10 mg l^-1) also contained the highest percentage of livestock feeding operations. The mean IBI score for streams draining agricultural land was higher than the mean value for forested streams when all streams were compared. However, when several streams that were only marginally forested (< 50%) were removed from the analysis, the IBI scores did not differ significantly by land use. Two physical habitat indices exhibited a strong associated with each other. Each habitat index also correlated with IBI values.     

Improving biological indicators to better assess the condition of streams

Biological indicators of stream condition are in use by water resource managers worldwide. The State of Maryland and many other organizations that use Indices of Biotic Integrity (IBIs) must determine when and how to refine their IBIs so that better stream condition information is provided. With completion of the second statewide round in 2004, the Maryland Biological Stream Survey (MBSS) had collected data from 2500 stream sites, more than doubling the number of sites that were available for the original IBI development. This larger dataset provided an opportunity for the MBSS to address the following shortcomings in the original IBIs: (1) substantial disturbance apparent in some reference sites, (2) fish IBIs could not be applied to very small streams, (3) natural variability within IBIs (based on regions) resulted in some stream types (e.g., coldwater and blackwater streams) receiving lower IBI scores and (4) one IBI was not able to discriminate degradation as desired (i.e., Coastal Plain fish IBI). Therefore, development of new fish and benthic macroinvertebrate IBIs was undertaken to achieve the goals of: (1) increased confidence that the reference conditions are minimally disturbed, (2) including more natural variation (such as stream size) across the geographic regions and stream types of Maryland and (3) increased sensitivity of IBIs by using more classes (strata) and different metric combinations. New fish IBIs were developed for four geographical and stream type strata: Coastal Plain, Eastern Piedmont, warmwater Highlands and coldwater Highlands streams; new benthic macroinvertebrate IBIs were developed for three geographical strata: Coastal Plain, Eastern Piedmont and Highlands streams. The addition of one new fish IBI and one new benthic macroinvertebrate IBI partitioned natural variability into more homogeneous strata. At the same time, smaller streams (i.e., those draining catchments <300 ac), which constituted a greater proportion of streams (25%) sampled in Round Two (2000–2004) than Round One (1995–1997), because of the finer map scale, were included in the reference conditions used to develop the new IBIs. The resulting new IBIs have high classification efficiencies of 83–96% and are well balanced between Type I and Type II errors. By scoring coldwater streams, smaller streams and to some extent blackwater streams higher, the new IBIs improve on the original IBIs. Overall, the new IBIs provide better assessments of stream condition to support sound management decisions, without requiring substantial changes by cooperating stream assessment programs.     

The use of fish in ecological assessments

Abstract Fish provide powerful tools for assessing aquatic environments. Three attributes are especially significant: the sensitivity of fish to most forms of human disturbance, their usefulness at all levels of biological organization and the favourable benefit-to-cost ratio offish assessment programmes. Fish can be used as indicators over wide temporal and spatial ranges. Because they cover all trophic levels of consumer ecology, fish can effectively integrate the whole range of ecological processes in waterways. Fish have been used in many different roles for assessing river health and monitoring responses to remedial management. Three of these applications appear to have particular value for management of Australian rivers: (i) automated systems monitoring fish ventilation can provide sensitive, broad-spectrum and continuous sensing of water quality to protect receiving waters or water-supply intakes; (ii) programmes collecting routine data on commercial or recreational fisheries can be designed and analysed so as to isolate confounding effects due to fishery-specific factors and, hence, used to detect and monitor environmental change on large scales; (iii) the Index of Biotic Integrity (IBI) can be modified to suit Australian conditions and fish communities to meet the important need for a predictive model of aquatic environmental quality. The IBI is a quantitative biological tool with a strong ecological foundation that integrates attributes from several levels of ecosystem organization. Examples of the use of IBI elsewhere suggest its robustness, flexibility and sensitivity can cope effectively with the low diversity of the Australian fish fauna and the dominance of ecological generalists. A provisional structure is suggested for a test of the IBI in four riverine regions of New South Wales.     

Large-scale assessments of river health using an Index of Biotic Integrity with low-diversity fish communities

1. Effective tools are needed to measure the ‘health’ of rivers at scales large enough to be useful for management. Indicators for assessing the complex of variables that constitutes river health need to be ecologically based, efficient, rapid and consistently applicable in different ecological regions. 2. A large-scale survey of rivers in New South Wales, Australia provided data to test the Index of Biotic Integrity (IBI). The IBI employs the fish-community attributes, identified using regional and river-size data, expected for a river reach of excellent environmental quality. It uses metrics based on species richness, abundance, community structure and the health of individual fish. IBI metrics were established to suit a relatively low-diversity and unspecialized freshwater fish fauna in south-eastern Australia, totalling 55 species. 3. The IBI was able to discriminate between relative levels of environmental quality within a diverse set of stream systems and four presumptive ecological regions. The index was validated by testing the repeatability of scores, and by comparison of IBI scores at eighty sites with an independent measure of potential catchment condition, the River Disturbance Index. 4. Assessments of metric performance showed that eleven of the twelve metrics contributed satisfactorily. One metric based on trophic guild performed poorly and should be deleted from the index. Six other recommendations are made to enhance the performance of the IBI. 5. Results show that, while all large rivers have been disturbed, rivers in the Murray region and those in many coastal montane areas are particularly degraded. 6. The IBI results presented here demonstrate a validated method for large-scale monitoring of river health based on a fish fauna of limited diversity, in the absence of suitable reference sites.     

Biogeography of benthic macroinvertebrates in estuaries along the Gulf of Mexico and western Atlantic coasts1,2

A multimetric fish Index of Biotic Integrity (IBI) was composed to assess the biotic integrity of Flandrian water bodies. As fish communities differ substantially between standing waters, running waters of the bream zone and running waters of the barbel zone, eight candidate metrics for each of these water types or zones were identified, representing three major classes of biological attributes. These are species richness and composition, fish condition and abundance, trophic composition. The metrics were tested and modified where needed. The IBI was applied throughout Flanders on 104 locations in standing waters, 500 locations in waters of the bream zone and 257 locations in waters of the barbel zone. Standing waters scored substantially different from running waters. Standing waters rarely contained no fish at all, but their fish communities were very often poor to very poor. Waters of the bream and barbel zone were often fishless (respectively 40% and 35% of all locations contain no fish), but the locations with fish usually scored reasonable to poor. Only 18.5% of all locations were classified as reasonable to excellent (IBI classes 4 or lower on a scale from 1 to 9) and were considered to satisfy the basic ecological quality demands. The Leie-, Dijle-, Dender- and Schelde-basins had a very poor quality (more than 50% of the locations contained no fish). The Maas-, Grote and Kleine Nete-basins scored rather well, with respectively, 44%, 48% and 68% of the locations achieving an IBI of 4 or lower. The IBI is a valuable and complementary tool to assess the ecological quality of water bodies as suggested in the proposal for a Water Framework Directive by the European Commission.     

Development of a preliminary index of biotic integrity (IBI) based on fish assemblages to assess ecosystem condition in the lakes of central Mexico

The lakes of central Mexico have great cultural, economic, and biological value, but they are being degraded at an accelerating rate. We employed historical data on fish communities from 19 of these lakes and case studies of community responses to environmental degradation from four of the best-studied, Xochimilco, Cuitzeo, Chapala, and Pátzcuaro, to construct a preliminary index of biotic integrity (IBI). This IBI was designed to be an easily applied method for assessing lake ecosystem health and evaluating restoration efforts. The IBI had 10 metrics: number of total native species, number of common native species, number of native Goodeidae species, number of native Chirostoma species, number of native sensitive species, percent of biomass as tolerant species, percent of biomass as exotic species, percent of biomass as native carnivorous species, maximum standard length of native species, and percent of exotic invertebrate parasite species on or in native fishes. Initial applications of the index showed promise, accurately ranking the relative degradation of the four case-study lakes. Further tests of the index are warranted, and more data are needed to standardize sampling procedures, improve species classifications, and refine metric scoring criteria.     

Assessment of an index of biological integrity (IBI) to quantify the quality of two tributaries of river Chenab,Sialkot, Pakistan

Nullah Aik and Nullah Palkhu, two tributaries of river Chenab, were investigated for the assessment of fish habitat degradation as indicator of stream health. Fish abundance data were collected from 18 sites from September 2004 to April 2006 to develop multimetric indices for fish assemblage integrity and to detect the intensity of habitat degradation. A total of 12 metrics were calculated on the basis of taxonomic richness, habitat preference, trophic guild, stress tolerance and origin of species to develop stepped and continuous index of biological integrity (IBI) criteria. Cluster analysis (CA) classified sites based on species composition into three groups, viz., reference, moderately impaired and impaired groups. Non-metric multidimensional scaling (NMDS) was applied to identify underlying ecological gradient to highlight the habitat degradation. NMDS segregated two sites as less impaired, five sites as moderately impaired and eleven sites as impaired groups. Axes 1 and 2 explained a total variation of 53.3%. First axis explained the level of habitat impairment, whereas axis 2 indicated species richness along longitudinal gradient of streams. Sites located upstream of Nullah Aik showed higher IBI scores which dropped to its lowest in downstream sites near Sialkot city. Lowest values of IBI of sites in close proximity of city indicated the role of anthropogenic activities in catchment areas. The results indicated that variability in water chemistry can be related as a function of stream sites impairments (i.e., unimpaired, moderately impaired, and severely impaired). Water quality parameters showed strong correlation with IBI scores. Significantly negative correlation of IBI scores with COD, TDS, turbidity, Fe, Cr, Zn and positive correlation with DO and pH was found. The results can be used for restoration and future management of small streams passing through urban areas of Pakistan. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: J. A. Cambray     

Monitoring temporal changes in the biology of acid waters

1. Assemblages of epilithic diatoms, macrophytes, benthic macroinvertebrates and fish were monitored over a 5-year period (1988–92) in ten lakes and nine streams in the U.K., as part of the U.K. Acid Waters Monitoring Network. All organisms were categorized according to their functional or morphological characteristics and integrated to describe the food web at each site. In general, the flora and fauna of all sites were typical of oligotrophic, softwater systems subject to various degrees of acidification. 2. Salmonids were the only fish caught at any site and brown trout were the dominant species. With only 5 years of data it was not possible to test for directional changes in fish populations at each site. Among sites, fish density was positively associated with pH, and this did not vary between lake outflows and streams or between fish of different age class (0 +, 1 +). Condition factor, reflecting fish health, was not associated with pH among sites, but was negatively associated with fish density and, on average, was higher for fish in streams than those in lake outflows. 3. Variability in the diatom, macrophyte and invertebrate data sets were quantified in three ways using multivariate techniques: species turnover or replacement (temporal variation due to directional change), persistence (the reciprocal of between-year variability) and within-year variability (heterogeneity between sample replicates). For all groups, turnover was relatively low and persistence was high. The least persistent macrophyte assemblages occurred in stream sites and this may reflect high inter-annual variation in the cover of filamentous algae which are prone to scouring. Within-year variability was higher than turnover or between-year variability for the diatoms and invertebrates, and highest values were recorded for lake invertebrates. 4. Redundancy analysis, RDA, was used to test the diatom, macrophyte, invertebrate and food web data for evidence of directional changes over time and its significance was assessed using Monte Carlo permutation tests. These tests appeared robust to temporal and spatial variability in the data set. Significant trends could be identified in some data sets despite considerable between-replicate and non-linear between-year variability. 5. Significant linear trends in at least one biological group were found at eight lake and seven stream sites. Only one lake and one stream had significant trends in all four groups. These trends represent changes in the flora and/or fauna, but they can be interpreted in several different ways. Only six sites showed trends that were consistent with our knowledge of species’ responses to water chemistry: three indicated increased acidity and three indicated decreased acidity. At only one site were the biological results consistent with observed chemical changes and there was disagreement at the other five. Of the other nine sites that showed biological changes, two appeared to reflect known physical habitat disturbances; the other seven remain unexplained.     

Modification of an index of biotic integrity based on fish assemblages to characterize rivers of the Seine Basin,France

The Index of Biotic Integrity (IBI) is a measure of fish assemblage health that has been used to assess catchment and stream quality throughout North America. It reflects human perturbations on natural environmental structures and processes. While preserving the ecological foundation of the original North American metrics, we have modified and adapted the IBI to the mainstem Seine River and its major tributaries in France. This successful modification of the IBI to a considerably different fish fauna on a different continent further supports its wider use outside the midwestern United States. Using data collected in 1967, 1981, and 1988–1989 from a total of 46 sites, we show spatial and temporal variation in the Seine as indicated by IBI scores. Statistically significant relationships were found between IBI and catchment area but insignificant relationships existed between IBI and an independent Water Quality Index (WQI) based on water chemistry. Comparisons between the IBI and the WQI indicate that the former is a more sensitive and robust measure of water body quality. Our results demonstrate that the IBI, combined with a statistically designed national monitoring program, would offer a reliable means of assessing spatial patterns and temporal trends in water body improvement or degradation in France. The more primitive fish families in the Basin were affected first by perturbations. These families include all the diadromous species found in the Seine and suggest serious disruption of their life histories.     

The application of chemical and biological multi-metric models to a small urban stream for ecological health assessments

Nutrient or/and organic pollutions have been used as one of the key factors influencing the stream health, so research approaches were frequently focused on chemical analysis rather and biological analysis. Our objective of the present study was to diagnose the chemical and biological stream health using chemical multi-metric model of nutrient pollution index (NPI) and biological multi-metric fish model of the index of biotic integrity (IBI), respectively in an urban stream. Seven years dataset from 2008 to 2014 were used for the health assessments. The nutrients regime (TN, TP), sestonic chlorophyll, total suspended solids (TSS), electrical conductivity, BOD, and COD showed a typical polluted stream with large temporal and spatial fluctuations due to variations of Asian monsoon rain. The analysis of fish trophic guilds and fish tolerance guilds showed that omnivore fish species and tolerant species were dominated the community and the proportions were directly determined by water chemistry (nutrient and organic matters). Chemical model of NPI showed “poor-very poor health condition” by the criteria of the model and showed same results with the biological model of fish IBI. The degradation of the stream health was mainly due to massive effluents from the wastewater treatment plants. Overall, our data suggest that the multi-metric chemical and biological models may be used as a key tool diagnosing the stream health condition in an urban stream.     

An index of biotic integrity based on fish assemblages for subtropical streams in southern Brazil

Several methods for calculating indices of biological integrity (IBIs) have been developed for different ecogeographic regions of the world. All of them calculate IBI scores by comparing against reference sites or historical data on fish assemblage composition. Because of intensive agriculture and urbanization in our study area, we located no reference sites, and historical information about fish assemblage composition did not exist. Instead, we developed hypothetical reference scores based on seasonal electrofishing surveys at six study sites in adjacent but geomorphologically different watersheds. Our IBI included 10 metrics that varied with degree of degradation. We found that Shannon–Wiener indices varied significantly between seasons, indicating significant changes in species composition. Therefore, we calculated seasonal IBI scores also, but these did not significantly differ from each streams general IBI score, which was calculated on the basis of four samples per site. General stream IBI scores reflected differing levels of anthropogenic disturbance.     

基于鱼类物种状况的长江生态环境质量评估

鱼类是水域生态系统的重要组成部分, 也是水域生态环境良好的指示类群。为合理评估长江生态环境的现状和变化趋势, 文章提出将土著鱼类物种数和珍稀特有鱼类物种数作为评价指标, 并建立了相关的评价基准和等级划分标准。以2010年和2020年为评价年, 评估了长江干流及代表性重点水域的生态环境质量。结果显示, 当前长江上游干流和下游干流的生态环境质量优于中游; 支流赤水河的生态环境质量良好, 大型湖泊鄱阳湖的生态环境质量中等。从时间上看, 随着长江十年禁渔等一系列保护措施的实施, 长江干流的生态环境质量有不同程度地好转。在此基础上, 提出了进一步改善长江生态环境的对策与建议。     

The influence of variability in species trait data on community‐level ecological prediction and inference

Species trait data have been used to predict and infer ecological processes and the responses of biological communities to environmental changes. It has also been suggested that, in lieu of trait, data niche differences can be inferred from phylogenetic distance. It remains unclear how variation in trait data may influence the strength and character of ecological inference. Using species‐level trait data in community ecology assumes intraspecific variation is small in comparison with interspecific variation. Intraspecific variation across species ranges or within populations may lead to variability in trait data derived from different scales (i.e., local or regional) and methods (i.e., mean or maximum values). Variation in trait data across species can affect community‐level relationships. I examined variability in body size, a key trait often measured across taxa. I collected 12 metrics of fish species length (including common and maximum values) for 40 species from literature, online databases, museum collections, and field data. I then tested whether different metrics of fish length could consistently predict observed species range boundary shifts and the impacts of an introduced predator on inland lake fish communities across Ontario, Canada. I also investigated whether phylogenetic signal, an indicator of niche‐conservativism, changed among measures. I found strong correlations between length metrics and limited variation across metrics. Accordingly, length was a consistently significant predictor of the response of fish communities to environmental change. Additionally, I found significant evidence of phylogenetic signal in fish length across metrics. Limited variation in length across metrics (within species), in comparison with variation within metrics (across species), made fish species length a reliable predictor at a community‐level. When considering species‐level trait data from different sources, researchers should examine the potential influence of intraspecific trait variation on data derived by different metrics and at different scales.     

Biological quality metrics: their variability and appropriate scale for assessing streams

The concept of spatial scale is at the research frontier in ecology, and although focus has been placed on trying to determine the role of spatial scale in structuring communities, there still is a further need to standardize which organism groups are to be used at which scale and under which circumstances in environmental assessment. This paper contributes to the understanding of the variability at different spatial scales (reach, stream, river basin) of metrics characterizing communities of different biological quality elements (macrophytes, fishes, macroinvertebrates and benthic diatoms) as defined by the Water Framework Directive. For this purpose, high-quality reaches from medium-sized lowland streams of Latvia, Ecoregion 15 (Baltic) were sampled using a nested hierarchical sampling design: (river basin → stream → reach). The variability of metrics within the different groups of biological quality elements confirmed that large-bodied organisms (macrophytes and fish) were less variable than small-bodied organisms (macroinvertebrates and benthic diatoms) at reach, stream and river basin scales. Single metrics of biological quality elements had the largest variation at the reach scale compared with stream and basin scales. There were no significant correlations between biodiversity indices of the different organism groups. The correlation between diversity indices (Shannon’s and Simpson’s) of the biological quality elements (macrophytes, fish, benthic macroinvertebrates and benthic diatoms) and a number of measured environmental variables varied among the different organism groups. Relationships between diversity indices and environmental factors were established for all groups of biological quality elements. Our results showed that metrics of macrophytes and fish could be used for assessing ecological quality at the river basin scale, whereas metrics of macroinvertebrates and benthic diatoms were most appropriate at a smaller scale.     

Characterization of tropical near-shore fish communities by coastal habitat status on spatially complex island systems

Synopsis We present a protocol for characterizing near-shore fish habitat as well as fish communities for Andros Island, Bahamas, a complex coastal-reef island system. Benthic assessments and beach seine surveys were carried out at sites varying in coastal and benthic characteristics. Temporal variability affected fish community composition, indicating that attempts to characterize a fish community should include sampling evenly across tides, times of day, and seasons. Univariate and multivariate analyses revealed that each site harbored a unique fish community, with the greatest variability within each site attributed to seasonal changes. Measures of diversity (Shannon–Weiner Index and number of species) were markedly different at sites with varying coverage of seagrass and macro-algae and extents of disturbance. Total abundance of fishes was positively related to the percent of bare sand. We suggest that thorough sampling of coastal fish communities can be applied to comparative and long-term studies. This protocol for the characterization of complex island habitats can be applied to ecological studies aimed at understanding the responses of fishes to small-scale changes in coastal areas and habitat structure due to land use and shoreline alterations.     

Long-term changes in ecosystem health of two Hudson Valley watersheds, New York, USA, 1936–2001

We examined long-term ecological change in two Hudson River tributaries, the Wappinger and Fishkill Creek watersheds in Dutchess County, New York State. Fish data spanning 65 years (1936, 1988, 1992, and 2001) and shorter term macroinvertebrate data (1988, 2001) were used to assess the influence of land use practices. Between 1988 and 2001, macroinvertebrate index Biotic Assessment Profile (BAP) improved by 113–165% in the Fishkill Creek watershed, and fish Index of Biotic Integrity (IBI) improved by 117–140%. Fish IBI and fish species richness were significantly different (p < 0.01) between the watersheds, with Wappinger Creek in better condition. Long-term fish IBI scores showed degradation in both watersheds since the 1930s. Changes in species composition suggest community homogenization on par with overall changes in the fish fauna of New York. Most notable were increases in tolerant species and declines in intolerant or moderately tolerant species. Whereas Fishkill Creek IBIs showed decline in 1988 relative to 1936, followed by improvement, Wappinger Creek declined monotonically in environmental quality. Development has intensified in both watersheds, but Fishkill Creek is improving while Wappinger Creek watershed is undergoing less mitigated degradation. We find that older, semi-quantitative data can be used to construct environmental quality indicators, and can be of great use for measuring long-term change.     

Small scale application and assessment of a Index of Biotic Integrity for a large boreal river

Modifications and use of Karr’s Index of Biotic Integrity (IBI) for assessing the effects of anthropogenic impacts to aquatic ecosystems have typically occurred using data collected at the macro scale. However, some non-point sources of habitat degradation occur at small scales. One possible source of perturbation to fish habitat in boreal rivers is the application of rip rap shoreline armouring in human use areas. In this study we assess the use of IBI in a small scale setting and discuss the potential impact of rip rap shoreline armouring. We captured small and juvenile fishes weekly during 2002–2003 from 12 sample sites within the littoral zone of a human use area using a modified beach seine. Principal component analysis (PCA) was performed on the data to examine the relationship between species composition and IBI scores. We also performed PCA on the IBI metrics to assess our modifications. The IBI method produced higher scores for armoured sites than for unarmoured sites. We found a strong rank order correlation (Spearman’s ρ > 0.93; p < 0.001) between the modified IBI scores and the first principal component, suggesting that Karr’s original empirically-based IBI is strongly linked to species composition. We found a high degree of redundancy between the metrics of the IBI that validate our modifications. These results suggest that IBI can be a suitable method for assessing non-point impacts from within a small study area. Our results also indicate that fish habitat from rip rap armoured sites within the test area had consistently higher IBI scores that unarmoured sites.     

Calculating Background Levels for Ecological Risk Parameters in Toxic Harbor Sediment

Establishing background levels for biological parameters is necessary in assessing the ecological risks from harbor sediment contaminated with toxic chemicals. For chemicals in sediment, the term contaminated is defined as having concentrations above background and significant human health or ecological risk levels. For biological parameters, a site could be considered contaminated if levels of the parameter are either more or less than the background level, depending on the specific parameter. Biological parameters can include tissue chemical concentrations in ecological receptors, bioassay responses, bioaccumulation levels, and benthic community metrics. Chemical parameters can include sediment concentrations of a variety of potentially toxic chemicals. Indirectly, contaminated harbor sediment can impact shellfish, fish, birds, and marine mammals, and human populations. This paper summarizes the methods used to define background levels for chemical and biological parameters from a survey of ecological risk investigations of marine harbor sediment at California Navy bases. Background levels for regional biological indices used to quantify ecological risks for benthic communities are also described. Generally, background stations are positioned in relatively clean areas exhibiting the same physical and general chemical characteristics as nearby areas with contaminated harbor sediment. The number of background stations and the number of sample replicates per background station depend on the statistical design of the sediment ecological risk investigation, developed through the data quality objective (DQO) process. Biological data from the background stations can be compared to data from a contaminated site by using minimum or maximum background levels or comparative statistics. In Navy ecological risk assessments (ERA's), calculated background levels and appropriate ecological risk screening criteria are used to identify sampling stations and sites with contaminated sediments.     

Integrative assessment of Western Himalayas streams using multimeric index

Multimeric index based on fish composition was used to assess integrity of shallow and wadeable streams of lower Himalayas in temperate and subtropical ecoregions. Streams were surveyed for biotic and abiotic sampling during base flow periods in pre and post monsoon seasons in 2007 and 2008. Twenty three metrics were computed based on taxonomic richness, trophic composition, habitat preferences, abundance, stress tolerance and species origin attributes of 19 fish species. Candidate metrics were analyzed for efficiency to discriminate degraded sites from non-degraded and redundancy analysis, which sorted 71% of omnivore individuals (excluding intolerant species), 40% of intolerant individuals, 44% of herbivore individuals (excluding benthic species), abundance and 44.5% of non-native individuals as potential metrics. IBI values at forest, agriculture and urban zones were ranged between (max–min) 9.9–3.22, 6.18–2.49 and 4.43–0.69 respectively. Results suggested that poor ecological conditions in streams were generally related to drainage of urban sewage and habitat fragmentation while agriculture land use seems to have moderate impact on ecological integrity of the streams. Less urbanized upstream with grasslands and forests as land use, showed excellent to good ecological integrity of the streams. Proposed index was able to distinguish varying degrees of human impact on ecological integrity of streams and thus index could be used as valuable tool for bioassessment of regional flowing water resources.