Index Of Biotic Integrity Metrics Research Articles

Nearshore Habitat and Fish Assemblages along a Gradient of Shoreline Development

AbstractLittoral habitat is a critical component of lake ecosystems. Expansion of residential development along lakeshores has led to habitat modification, which may alter lentic fish communities. Previous studies have linked lakeshore development to reductions in abundance of aquatic vegetation and coarse woody structure (CWS), and many have quantified the influence of the density of docks on aquatic habitat structure and individual fish species. However, few studies have quantified fish assemblages relative to the effect of density or pattern of development. Using docks as a proxy for development, we calculated dock density, cumulative dock area, and estimates of the proportion of shoreline that was developed, affected by development, or left in large undeveloped segments for 28 Minnesota lakes. We assessed nearshore structural habitat (aquatic vegetation, CWS, and riparian features), a lake‐wide fish index of biotic integrity (IBI), and nearshore components of the fish IBI relative to the development measures derived from docks. The nearshore IBI metrics were community composition metrics based on the proportion of intolerant, small benthic‐dwelling, and vegetation‐dwelling species caught in nearshore sampling, which we also evaluated individually and summed as a nearshore IBI. All measures of development were correlated and performed similarly in our models. Emergent vegetation and CWS declined with increasing development. Nearshore fish IBI declined with increasing development, but the lake‐wide IBI did not change significantly with development. The decline of the nearshore fish IBI appeared to have been driven by a decline in vegetation‐dwelling species.Received June 9, 2016; accepted January 6, 2017 Published online March 15, 2017

Relationships among varying sampling distance and the IBI in warmwater, headwater streams of the Eastern Corn Belt Plain.

Single-pass electrofishing was used to define the most efficient sampling distance to assess stream condition using the index of biotic integrity (IBI) methodology in headwater (<36 km(2) drainage area), warmwater streams in the Eastern Corn Belt Plain ecoregion. Based on wetted widths (1-3.3 m) of sampled reaches, we defined effort based on increased area (range 50-555 m(2)). Sampled area necessary to capture a representative fish assemblage increased until 167-m(2) distance, which is equivalent to a minimum sampling distance of one habitat cycle. No significant difference in metric actual observed value response was found with increasing habitat cycle. Increased effort is required in smaller streams widths (≤1 m) to achieve the recommended sample area. The effect of rare fish on the IBI was tested using a modified Walford method. A significant decrease in IBI score was observed when 10% of the rare data were removed. The presence of rare fish did not influence individual IBI metrics or scores for either the increased effort or reduced effort calibrations until greater than 3% of the data was removed for number of species, 15% removal of data for number of minnow species, and 5% removal of data for catch per unit effort (CPUE). Increased effort did not affect any metric or IBI score, while reduced effort influenced the number of darter, madtom, and sculpin species and catch per unit effort metric scores but did not affect IBI score.

Patterns in Stream Fish Assemblage Structure and Function Associated With a PCB Gradient

Stream fish assemblage structure and function were examined for significant response along a polychlorinated biphenyl (PCB) gradient from two PCB-contaminated streams (Clear Creek and Richland Creek watershed) at three locations and a control stream (Little Indian Creek), Indiana, USA. Fish were sampled in the summer months of 1995 and from 1999 to 2002. 51 fish assemblage attributes-including structure (i.e., fish composition) and function (i.e., trophic, reproductive, condition guilds), biomass, and index of biotic integrity (IBI) metric scores-were evaluated for significance according to an increasing PCB gradient. Eight biomass attributes of fish assemblages decreased with increasing PCB concentration: number of species biomass, number of sunfish biomass, percent sunfish biomass, number of sucker biomass, percent sucker biomass, biomass of sensitive species, percent sensitive species biomass, and percent carnivore biomass. Three biomass attributes increased with PCB concentration: percent minnow biomass, percent pioneer species biomass, and percent tolerant species biomass. Seven species composition and relative abundance characters decreased with increasing PCB concentration: number of species; number of darter, madtom, and sculpin; number of darter; number of sunfish; number of sucker; number of sensitive species; and percent individuals as carnivores. Percent individuals as pioneer species increased with increasing PCB concentration. Two IBI metrics, percent individuals as headwater species and number of minnow species, increased as PCB concentrations increased, whereas number of sucker species and percent individuals as pioneer species decreased with increasing PCB concentration class. We observed a direct response between decreased relative abundance and biomass of carnivores and increased relative abundance minnows as the PCB gradient increased. Total IBI score did not detect subtle changes to the fish community that were observed along a PCB gradient, whereas diagnostic analysis of the individual metrics did.

Macrophyte Species Distribution, Indices of Biotic Integrity, and Sampling Intensity in Isolated Florida Marshes

This study examined the distribution of wetland plants used in macrophyte-based index of biotic integrity (IBI) metrics to determine the effectiveness of zone sampling in assessing wetland condition. Using sampling data from a previous study of 74 emergent isolated wetlands, macrophyte taxonomic data and resulting IBI metrics were analyzed for various wetland zones and compared against the original site metrics. Zones were defined by parsing each sampling transect (from wetland edge to center) into thirds—creating an outer, intermediate, and inner zone—and constructing two additional zones representing two-thirds of the original sampling area—an outer plus intermediate zone and an intermediate plus inner zone. While a highly-significant decrease in mean species richness was observed from the wetland exterior to interior, there were no significant differences between metric values derived from site data and those derived from zone data. Linear correlations between metrics from the outer zone and site data were highly significant (R 2 > 0.94), but linear correlation strength decreased with the intermediate and inner zones, respectively. Thus, macrophyte-based indicators of biological integrity can be efficiently assessed by sampling the outer third of a wetland—a 66% reduction in the area and effort required to monitor isolated wetland condition.

Comparability of a regional and state survey: effects on fish IBI assessment for West Virginia, U.S.A.

Probability-based survey designs are now being investigated to allow condition to be assessed for a discrete population of watershed management units and to infer probability of impairment to other unsampled watersheds. Results can be used to focus further monitoring and restoration efforts. Fish community data and index of biotic integrity (IBI) development were compared between the 1993 and 1998 Environmental Monitoring and Assessment Program Mid-Atlantic Integrated Assessment (EMAP-MAIA) survey and a West Virginia Regional EMAP (WV REMAP) survey conducted in 2001-2002. Both designs were based on probability surveys, but the EMAP design treated streams as a continuous linear network comprising an infinite population of points, while the REMAP design used a discrete set of watershed outlets as defined by 12-digit Hydrologic Cataloging Units (HUC12) as the sample population. The comparability of the watershed-based WV REMAP survey design results with the linear network-based EMAP-MAIA survey results for West Virginia was affected by the different size range of watershed areas included in each target population. Once similar watershed area ranges were considered by narrowing the size range included in the West Virginia EMAP-MAIA data set, virtually identical cumulative distribution functions for fish IBI scores were obtained. The reduced variability in reference conditions obtained by applying a restricted range of watershed areas allowed us to detect and correct for ecoregional differences in fish IBI metrics and scores, after excluding the biogeographically distinct Potomac River drainage basin located in the Central Appalachian Ridge and Valley Ecoregion.

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.

Development and Evaluation of a Fish Assemblage Index of Biotic Integrity for Northwestern Great Plains Streams

AbstractQuantitative indicators of biological integrity are needed for streams in the Great Plains of North America, but it was not known whether the index of biotic integrity (IBI) approach would be effective in this semiarid region. Great Plains streams have a depauperate and tolerant ichthyofauna and highly variable physicochemical conditions that may mask the effects of non‐point‐source pollution and stream habitat degradation. We developed an IBI based on fish assemblages by screening metrics for range, responsiveness to human influence, precision, and lack of redundancy; we then tested the IBI's ability to detect anthropogenic effects by validating the index with an independent data set. The IBI was composed of 10 metrics based on species richness and composition, trophic and reproductive guilds, and age structure. These 10 metrics had many significant correlations with substrate and water chemistry variables but had fewer significant correlations with riparian condition and watershed variables. Of the watershed variables, road density had the highest number of significant correlations with final IBI metrics. The IBI was validated by demonstrating its responsiveness to aggregate measures of human influence, site‐level habitat, and water chemistry, and its lack of responsiveness to factors that varied naturally, such as stream size and site elevation. The IBI was also temporally stable within and between years during repeat visits to a subset of sampled reaches. This IBI can be used as a measure of biological integrity for management of prairie streams faced with threats such as introduced species, intensive agriculture, grazing, and coalbed natural gas extraction. Although we developed this IBI based on data from Montana prairie streams only, our IBI can probably serve as a framework for other North American plains streams and our results suggest that the IBI approach may be useful in other semiarid regions of the world.

Application of the Index of Biotic Integrity Methodology to New Zealand Freshwater Fish Communities

An index of biotic integrity (IBI) was developed for freshwater fish in New Zealand streams. Data on freshwater fish occurrence for 5497 sites over the entire country were obtained from the New Zealand freshwater fish database for the period 1980-2002. Environmental habitat descriptors for the stream watersheds above or at each of these sites were obtained from an existing river environment classification using a geographic information system. Of the many IBI metrics in use globally, only six were adapted and applied because of differences between the fish fauna of New Zealand and the United States. A number of evaluation methods showed that all six metrics contributed to the overall IBI scores with high levels of consistency. The IBI assessment of sites sampled at different times showed high levels of temporal concordance. The IBI scores differed significantly among the geological areas, the sampling method used, and the year of survey. Overall, the results presented demonstrate the potential for New Zealand freshwater fish to be used to assess river condition at large spatial scales in New Zealand in the absence of specifically selected reference sites. This application demonstrates the effectiveness of the IBI approach even with a fauna of limited diversity and limited ecological specialisation as in the New Zealand fish fauna.

Using an IBI to assess effectiveness of mitigation measures to replace loss of a wetland-stream ecosystem

Approximately 7.3 hectares of wetlands, composed of six separate cells, were created to mitigate the loss of a 6-hectare, beaver-influenced, wetland-stream complex destroyed by the construction of a multipurpose impoundment in the Cedar Run watershed in Fauquier County, Virginia, USA. The mitigation action physically replaced the lost wetlands and was judged successful in meeting planned objectives and regulatory requirements (which did not include standards for biota). A pre-project fish survey conducted in 1974 in the wetland-stream complex and three nearby streams provided a baseline condition from which to assess project impacts on fish, as determined from yearly surveys in the cells and the stream reach immediately upstream. In addition, fish communities were sampled at 157 stream locations within the northern Virginia Piedmont from 1997 to 1999 to establish a regional Index of Biotic Integrity (IBI) based on fish assemblages. A modification of that IBI was developed to assess the effectiveness of the mitigation based on 22 stream segments that were heavily influenced by beaver. Pre- and post-project conditions were assessed by gauging them against the wetland-stream complexes using this IBI. The IBI score for the mitigation area dropped from the pre-project 34 to 18 the first year after construction and ranged from 18 to 28 over the ten-year post-project monitoring period. A reduction in the number of native species was observed, and there was a dramatic shift in composition and relative abundance within key species groups. In general, the mitigation benefited species favoring lentic environments over those preferring lotic environments and had negative effects on trophic and habitat specialists and less tolerant species. Scores for the mitigation cells were lower than scores for the original wetlands for the following IBI metrics: number of darter species, number of minnow species, percent of the assemblage comprised of the single most dominant species, percent of tolerant individuals, percent of benthic invertivores, and percent of specialist carnivores minus tolerants. Upstream reach IBI scores also diminished over the same 10-year period, although more gradually. The IBI showed that, despite meeting all regulatory requirements, the mitigation failed to replace the original fish community in the wetland-stream complex and adversely impacted additional stream habitat. Using tools such as an IBI to monitor biological condition can help planners effectively mitigate unavoidable project impacts and avoid the unintended loss of important natural resources caused by compensatory mitigation actions.

A provisional fish index of biotic integrity for assessing Ouachita Mountains streams in Arkansas, U.S.A.

Multimetric indices are often used to monitor aquatic-resource conditions. We used existing fish-collection data from streams to develop an Index of Biotic Integrity (IBI), which is a multimetric index, for the Ouachita Mountains ecoregion in Arkansas, U.S.A. Each fish-collection site was categorized as reference or non-reference. We examined 62 candidate IBI metrics, and selected 12 non-redundant metrics that differentiated best between reference and non-reference sites. The selected metrics were: Percent (of individuals) as Black Bass; Percent as Benthic Feeders; Percent as Centrarchids; Percent as Cyprinids; Percent as Ictalurids; Percent as Mineral, Site-Prep Spawners; Percent as Mineral, Site-Prep, Parental-Care Spawners; Percent as Simple, Mineral Substrate Spawners; Percent as Miscellaneous, Site-Prep, Parental-Care Spawners; Total Number of Centrarchid Species; Total Number of Arkansas Department of Environmental Quality (ADEQ) Ouachita Mountains Indicator Species; and Total Number of ADEQ Ouachita Mountains Key Species. We standardized each metric to score from 0 to 10 by using linear equations and threshold limits. Some selected IBI metrics had their scoring criteria adjusted to account for watershed size (i.e., stream size). We standardized the IBI to score from 0 to 100. In addition, we determined that our Percent as Black Bass and Percent as Benthic Feeders metrics contributed most to IBI scores in reference conditions, but their contributions decreased with decreasing stream conditions. Reproductive metrics contributed most in degraded stream conditions. Furthermore, we identified relations between IBI metrics and water-quality and land-use variables; some relations were counterintuitive. Unexpected relations may be random observations explained by limited ranges of land-use and water-quality variables. When select water-quality and land-use variables were included in a principal component analysis, a composite Land Use Intensity variable explained most of the model variance. Although the IBI has not been independently validated, the PCA, as well as other superficial analyses, indicated that the IBI should be able to differentiate stream conditions.

AN INDEX OF BIOTIC INTEGRITY FOR FISH ASSEMBLAGES IN OZARK HIGHLAND STREAMS OF ARKANSAS

We developed an Index of Biotic Integrity (IBI) for wadeable Ozark Highland streams in Arkansas by using fish-assemblage data from 96 stream sites. All sites were classified as reference or non-reference based on both subjective and objective information, and we used uni- and bivariate statistics to examine 39 potential IBI metrics. Seven metrics were chosen for the IBI. They were percent (of individuals) as algivorous/herbivorous, invertivorous, and piscivorous; percent with black spot or an anomaly; percent green sunfish Lepomis cyanellus, bluegill L. macrochirus, yellow bullhead Ameiurus natalis, and channel catfish Ictalurus punctatus; percent invertivorous; percent top carnivores; number of darter Etheostoma and Percina, sculpin Cottus, and madtom Noturus species; and number of lithophilic spawning species. Trophic metrics contributed most to IBI scores, and metrics were most often correlated with chloride, nutrient, land use, road density, and sedimentation levels, which suggests that our IBI should be able to successfully differentiate stream conditions in wadeable Ozark Highland streams of Arkansas.

Weak correspondence between macroinvertebrate assemblages and land use in Prairie Pothole Region wetlands, USA

To evaluate the potential development of a macroinvertebrate Index of Biotic Integrity (IBI) for Prairie Pothole Region wetlands, we sampled the aquatic macroinvertebrate and fish communities in 24 semipermanent wetlands located throughout central North Dakota. Wetland basins were selected to encompass a range of surrounding land-use, ranging from 100% grassland to 100% cropland. We used redundancy analysis (RDA) to identify the influences of fish, and temporal and spatial variation on the macroinvertebrate community. We also used RDA to look for relationships between wetland macroinvertebrate communities and land-use. Seventeen potential invertebrate metrics were tested by graphical analyses. We identified a strong influence on the macroinvertebrate community due to the presence of fish. A number of invertebrate taxa decreased in abundance as the summer progressed, and there was noticeable variation in the invertebrate community among individual wetlands of the region. However, we detected no strong relationships between the varying degrees of agricultural land-use in the wetland catchments and the invertebrate community. Consequently, we were unable to identify and effective IBI metrics indicative of land-use disturbance. Lack of correspondence between land-use and macroinvertebrates in this habitat is most likely due to a high degree of natural disturbance (e.g., presence of fish, temporal changes) and a low diversity community of resilient taxa in Prairie Pothole Region wetlands.

Hydrologic variability and the application of Index of Biotic Integrity metrics to wetlands: A great lakes evaluation

Interest by land-management and regulatory agencies in using biological indicators to detect wetland degradation, coupled with ongoing use of this approach to assess water quality in streams, led to the desire to develop and evaluate an Index of Biotic Integrity (IBI) for wetlands that could be used to categorize the level of degradation. We undertook this challenge with data from coastal wetlands of the Great Lakes, which have been degraded by a variety of human disturbances. We studied six barrier beach wetlands in western Lake Superior, six drowned-river-mouth wetlands along the eastern shore of Lake Michigan, and six open shoreline wetlands in Saginaw Bay of Lake Huron. Plant, fish, and invertebrate communities were sampled in each wetland. The resulting data were assessed in various forms against gradients of human disturbance to identify potential metrics that could be used in IBI development. Our results suggested that the metrics proposed as potential components of an IBI for barrier beach wetlands of Lake Superior held promise. The metrics for Lake Michigan drowned-river-mouth wetlands were inconsistent in identifying gradients of disturbance; those for Lake Huron open embayment wetlands were yet more inconsistent. Despite the potential displayed by the Lake Superior results within the year sampled, we concluded that an IBI for use in Great Lakes wetlands would not be valid unless separate scoring ranges were derived for each of several sequences of water-level histories. Variability in lake levels from year to year can produce variability in data and affect the reproducibility of data collected, primarily due to extreme changes in plant communities and the faunal habitat they provide. Substantially different results could be obtained in the same wetland in different years as a result of the response to lake-level change, with no change in the level of human disturbance. Additional problems included limited numbers of comparable sites, potential lack of undisturbed reference sites, and variable effects of different disturbance types. We also evaluated our conclusions with respect to hydrologic variability and other major natural disturbances affecting wetlands in other regions. We concluded that after segregation of wetland types by geographic, geomorphic, and hydrologic features, a functional IBI may be possible for wetlands with relatively stable hydrology. However, an IBI for wetlands with unpredictable yet recurring influences of climate-induced, long-term high water periods, droughts, or drought-related fires or weather-related catastrophic floods or high winds (hurricanes) would also require differing scales of measurement for years that differ in the length of time since the last major natural disturbance. A site-specific, detailed ecological analysis of biological indicators may indeed be of value in determining the quality or status of wetlands, but we recommend that IBI scores not be used unless the scoring ranges are calibrated for the specific hydrologic history pre-dating any sampling year.

Development, Validation, and Application of a Fish-Based Index of Biotic Integrity for Wisconsin's Large Warmwater Rivers

We used fish assemblage data collected by daytime electrofishing during 1996–1999 from 155 main-channel-border sites on 30 large warmwater rivers in Wisconsin to construct, test, and apply an index of biotic integrity (IBI). Our goal was to develop an effective and rapid way to use fishes to assess the environmental quality of river ecosystems in the state. Fourteen sites were visited more than once for a total of 187 samples, 101 of which (randomly chosen) were used to develop the IBI and the remaining 86 to test it. Prior to sampling, sites were classified as “least impacted” or as affected by impoundments, daily “peaking” flows from hydropower dams, non-point-source pollution from the watershed, point source pollution from industrial and municipal discharges (within the last 35 years), or multiple human impacts. Of the 26 potential IBI metrics considered, 10 were chosen: the total weight of the catch (excluding tolerant species); the number of native, sucker, intolerant, or riverine specialist species; the percentage of the individuals captured that were deformed or diseased, riverine specialists, or simple lithophilous spawners; and the percentage of the total weight of the catch that were insectivores or round-bodied suckers. Six metrics had different scoring criteria for northern and southern Wisconsin. For both the test subset and the entire dataset, the least-impacted sites had significantly higher mean scores and lower temporal variation than the other site classifications, indicating that they had the best ecosystem quality. Multiple-impact and non-point-source sites had the lowest means and most variable scores, signifying degraded ecosystem quality. Impoundment and hydropower peaking sites had slightly but not significantly better scores. Peaking sites on river reaches that are highly fragmented by dams tended to have lower scores than peaking sites on relatively long (>60 km), contiguous river reaches. Point source sites had significantly better scores than multiple-impact and non-point-source sites, indicating benefits to biotic integrity from recent treatment of municipal and industrial discharges.

Determining a Regional Framework for Assessing Biotic Integrity of Virginia Streams

Abstract The utility of an index of biotic integrity (IBI) depends on its ability to distinguish anthropogenic effects on biota amid natural biological variability. To enhance this ability, we examined fish assemblage data from least-disturbed stream sites in Virginia to determine the best way to regionally stratify natural variation in candidate IBI metrics and their scoring criteria. Specifically, we examined metric variation among physiographic regions, U.S. Environmental Protection Agency ecoregions, and drainage basins to judge their utility as regions in which to develop and use distinct versions of the IBI for Virginia warmwater streams. Statewide, metrics differed most among physiographic regions; thus, we recommend their use as IBI regions. Largest differences were found for taxonomic metrics between coastal plain and mountain sites, particularly in numbers of native minnow (Cyprinidae), sunfish (Centrarchidae), and darter (Percidae) species. Trophic and reproductive metrics also differed between...

Modification of an index of biotic integrity for assessing vernal ponds and small palustrine wetlands using fish, crayfish, and amphibian assemblages along southern Lake Michigan

We developed an index of biotic integrity (IBI) based on crayfish, fish, and amphibian assemblages to assess vernal ponds and palustrine wetland habitats of less than 5 ha along the southern shore of Lake Michigan. We found that the modified IBI based on three crayfish, twelve fish, and seven amphibian species collected during our surveys provided a more complete assessment than one based on any single taxonomic group. The new scoring criteria included the number of amphibian and fish species, number of benthic species, percent of individuals as pioneer species, percent of individuals as exotic species and percent of individuals with complex reproductive modes for metrics developed for larger palustrine wetlands. Low-end scoring procedures were not required; however, species composition metrics that did not possess the specified attribute received a ‘0’ score rather than a ‘1’. Correlation coefficients suggest that the reference conditions developed during this study of IBI metrics are able to differentiate high-quality biological assemblages from disturbance gradients that lowered biological integrity in small palustrine wetlands and vernal ponds. We found that the distribution of the index scores for Miller Woods was skewed to the low end of biological integrity with increased distance from Lake Michigan and proximity to edges.

Use of an Index of Biotic Integrity to Detect Effects of Land Uses on Stream Fish Communities in West-Central Georgia

An index of biotic integrity (IBI) was developed for use in the lower piedmont and upper coastal plain physiographic regions of west-central Georgia to investigate the relation between stream fish communities and land use. Fish samples and habitat data were collected at 507 sites in 340 first- to fifth-order tributary streams in the Chattahoochee, Flint, Ocmulgee, and Oconee river drainages during 1990–1993. Watershed cutouts upstream of sample sites were made from raster digital files based on LANDSAT thematic mapper satellite imagery from land use and land cover data collected during the winters of 1988–1990. Six of the 12 original IBI metrics were modified to take into account regional ichthyological differences between Georgia and the midwestern United States while maintaining the basic underlying ecological assumptions. The number of darter species metric was expanded to include madtoms (Noturus spp.) and sculpins (Cottus spp.), number of intolerant species metric was expanded to include moderately intolerant species, proportion piscivores was modified for small streams where proportion pioneer species was substituted, proportion hybrid metric was deleted and proportion of lithophilic spawners was substituted, proportion green sunfish Lepomis cyanellus was replaced with proportion tolerant species, and the proportion of diseased fish metric was replaced with proportion of individuals in a sample with deformities, eroded fins, lesions, or tumors. Nonpoint and point source runoff from low-density urban areas negatively influenced the number of fish species, number of darter species, number of individuals, proportion of insectivorous cyprinids, and proportion of lithophilic spawners. Proportions of tolerant species and proportions of species with deformities, eroded fins, lesions, or tumors were positively related to increased levels of turbidity–suspended solids. In addition, higher levels of turbidity–suspended solids generally had a negative influence on the number of sensitive species, number of individuals, proportion of lithophilic spawners, and proportion of omnivores. The relationship between IBI site scores and measures of relative habitat quality suggested that the derived IBI was effective in differentiating stream quality.

Considerations regarding development of index of biotic integrity metrics for large rivers

The index of biotic integrity (IBI) is the most widely used multi-metric index to assess the biological health of fish communities. Numerous state-specific or basin-specific versions of the IBI have been developed for wadeable streams. However, progress has been considerably slower with regard to developing IBIs for large rivers. Sampling in large rivers presents a number of unique problems, many of which result from the size of the waterbody to be sampled. Topics covered in this paper include several related to field sampling such as electrofishing output requirements, day vs night sampling effectiveness, effectiveness of various gears and overlap among them, the lack of reference sites in large rivers, seasonal movements of fishes, variables affecting sampling efficiency, sampling effort, and QA/QC. Also discussed are several topics related to data analysis such as data variability, influence of YOY fishes on catch results, minimum size of the data set, metric calibration, proper characterization of trophic guilds, and establishment of tolerant/intolerant species. Before meaningful IBI scores can be generated, new metrics, applicable to large rivers, need to be developed. Based on the considerations discussed in this paper, it is recommended that large rivers be sampled by a combination of seining and electrofishing, with the electrofishing being conducted at night and with an effort of ≥500 m.

Modification of an index of biotic integrity for assessing vernal ponds and small palustrine wetlands using fish, crayfish, and amphibian assemblages along southern Lake Michigan

Abstract We developed an index of biotic integrity (IBI) based on crayfish, fish, and amphibian assemblages to assess vernal ponds and palustrine wetland habitats of less than 5 ha along the southern shore of Lake Michigan. We found that the modified IBI based on three crayfish, twelve fish, and seven amphibian species collected during our surveys provided a more complete assessment than one based on any single taxonomic group. The new scoring criteria included the number of amphibian and fish species, number of benthic species, percent of individuals as pioneer species, percent of individuals as exotic species and percent of individuals with complex reproductive modes for metrics developed for larger palustrine wetlands. Low-end scoring procedures were not required; however, species composition metrics that did not possess the specified attribute received a ‘0’ score rather than a ‘1’. Correlation coefficients suggest that the reference conditions developed during this study of IBI metrics are able to differentiate high-quality biological assemblages from disturbance gradients that lowered biological integrity in small palustrine wetlands and vernal ponds. We found that the distribution of the index scores for Miller Woods was skewed to the low end of biological integrity with increased distance from Lake Michigan and proximity to edges.

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

Summary1. 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.