Bioassessment in complex environments: designing an index for consistent meaning in different settings

Mazor, Raphael D.; Rehn, Andrew C.; Ode, Peter R.; Engeln, Mark; Schiff, Kenneth; Stein, Eric D.; Gillett, David J.; Herbst, David B.; Hawkins, Charles P.

doi:10.1086/684130

Cited by 59 publications

(91 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Predictive indices like the CSCI and its components are designed to have minimal influence from major natural gradients, and they can therefore be used as a measure of biological conditions with a consistent meaning in different environmental settings (Hawkins, Olson, & Hill, ; Reynoldson, Norris, Resh, Day, & Rosenberg, ). California Stream Condition Index scores and scores for each component were classified as indicating good or bad biological condition, using the 10th percentile of reference calibration scores as a threshold (Table , Mazor et al., ).…”

Section: Methodsmentioning

confidence: 99%

“…Sites were assigned to one of four classes based on having good or bad biological health, and altered or unaltered hydrological conditions (Table ). Sites with CSCI scores greater than 0.79 were designated as having biologically good health, and sites with lower scores were designated as biologically altered (Mazor et al., ). Hydrologic alteration was inferred using the hydrologic alteration index described above.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Tools for managing hydrologic alteration on a regional scale: Setting targets to protect stream health

et al. 2018

Self Cite

View full text Add to dashboard Cite

Widespread hydrologic alteration creates a need for tools to assess ecological impacts to streams that can be applied across large geographic scales. A regional framework for biologically based flow management can help catchment managers prioritise streams for protection, evaluate impacts of disturbance or interventions and provide a starting point for causal assessment in degraded streams. However, lack of flow data limit the ability to assess hydrologic conditions across a region. Hydrologic models can address this problem. Regionally calibrated hydrologic models were used to estimate current and reference flows at 572 bioassessment sites in southern and central coastal California. Flow alteration was characterised as the difference in 39 flow metrics calculated from simulations of present‐day and reference flow time‐series, calculated under up to four precipitation conditions. Biological condition was assessed with the California Stream Condition Index (CSCI) and its components. Logistic regressions were used to predict the likelihood of high scores (i.e. ≥10th percentile of the CSCI reference calibration data). Statistically significant relationships between increasing severity of hydrologic alteration and decreasing biological condition were used to set thresholds that reflected tolerance for risk of a stakeholder advisory group. An index of hydrologic alteration was created by selecting flow metrics based on their importance for predicting biological response variables in boosted regression tree models. Metrics were selected in the order of decreasing importance, and no more than two metrics per metric class were selected (i.e. duration, frequency, magnitude, timing and variability). Seven metrics were selected: HighDur (duration of high‐flow events), HighNum (# of high‐flow events), NoDisturb (duration between high‐ or low‐flow events), MaxMonthQ (maximum monthly discharge), Q99 (99th percentile of daily streamflow), QmaxIDR (interdecile range of annual maxima) and RBI (Richards–Baker Index). Applying the index to data from a probabilistic survey, 34% of stream‐miles in southern California were estimated to be hydrologically altered. One of four management priorities were assigned to each site based on biological condition and hydrologic status: protection (healthy and unaltered, 52% of stream‐miles), monitoring (healthy but altered 4%), evaluation of flow management (unhealthy and altered, 30%) and evaluation of other management (unhealthy but unaltered, 14%). Regionally derived biologically based targets for flow alteration allow catchment managers to prioritise activities and conduct screenings for causal assessments across large spatial scales. Furthermore, regional tools pave the way for incorporation of hydrologic management in policies and catchment planning designed to support biological integrity in streams. Development of regional tools should be a priority where hydrologic alteration is pervasive or expected to increase in response to climate change or urbanisation.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Tools for managing hydrologic alteration on a regional scale: Setting targets to protect stream health

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The initial scope of data covered in this analysis consists of 4,984 stream samples from 2,997 unique geographic locations across the state of California, constituting a 23‐year period (1994–2016) (Mazor et al, ). Every sample contains the following data: BMIs enumerated and sorted to a standardized level (generally a genus‐level identification except chironomids, which were identified to subfamily; Richards and Rogers, ), sample site altitude in meters, U.S. Geological Survey Hydrologic Unit Code 8 level watershed (Seaber, Kapinos, & Knapp, ), and the percent developed land use (agricultural, urban, and managed landscapes) within a 5 km clipped buffer of the watershed upstream of the sampling site, and a bioassessment index score (California Stream Condition Index [CSCI]) based on a composite of taxonomic and functional diversity within BMI assemblages (Mazor et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…The type and geographic extent of land use in the upstream vicinity of each sampling site data is derived from the National Land Cover Data set (NLCD) (Homer et al, ), with developed land cover measured by the total percent of land cover in a designated area dedicated to agriculture, urbanization, or otherwise managed vegetative landscapes such as golf courses. The designated area for calculating percent developed land cover at each site is defined using a 5 km watershed‐clipped buffer upstream of a stream sampling site using ArcGIS tools (version 10.3; Environmental Systems Research Institute) (Mazor et al, ). The values for land use were calculated from NLCD measurements acquired in the year 2000, though it should be noted that the sample sites in our study were located in areas where the percent developed land use was not significantly correlated with time over the duration of this study ( r = −.02, p = .27).…”

Section: Methodsmentioning

confidence: 99%

Using co‐occurrence network topology in assessing ecological stress in benthic macroinvertebrate communities

Simons

Mazor

Theroux

2019

Ecology and Evolution

View full text Add to dashboard Cite

Ecological monitoring of streams has often focused on assessing the biotic integrity of individual benthic macroinvertebrate (BMI) communities through local measures of diversity, such as taxonomic or functional richness. However, as individual BMI communities are frequently linked by a variety of ecological processes at a regional scale, there is a need to assess biotic integrity of groups of communities at the scale of watersheds. Using 4,619 sampled communities of streambed BMIs, we investigate this question using co‐occurrence networks generated from groups of communities selected within California watersheds under different levels of stress due to upstream land use. Building on a number of arguments in theoretical ecology and network theory, we propose a framework for the assessment of the biotic integrity of watershed‐scale groupings of BMI communities using measures of their co‐occurrence network topology. We found significant correlations between stress, as described by a mean measure of upstream land use within a watershed, and topological measures of co‐occurrence networks such as network size (r = −.81, p < 10–4), connectance (r = .31, p < 10–4), mean co‐occurrence strength (r = .25, p < 10–4), degree heterogeneity (r = −.10, p < 10–4), and modularity (r = .11, p < 10–4). Using these five topological measures, we constructed a linear model of biotic integrity, here a composite of taxonomic and functional diversity known as the California Stream Condition Index, of groups of BMI communities within a watershed. This model can account for 66% of among‐watershed variation in the mean biotic integrity of communities. These observations imply a role for co‐occurrence networks in assessing the current status of biotic integrity for BMI communities, as well as their potential use in assessing other ecological communities.

show abstract

“…One way to reduce the effect of heterogeneity is to stratify samples geographically or into environmentally similar groups (Stoddard, ). Stratifying samples according to spatial‐environmental similarity helps provide context and increases ability to detect patterns and changes not caused by natural variability (Mazor et al, ). As responses of indicator species vary between regions and along environmental gradients (Zettler et al, ), optimal application may require geographic and environmental specification.…”

Section: Introductionmentioning

confidence: 99%

Enhanced indicator species performance with increasing contextualization

Bried

Fouts

Jog

2019

Conservat Sci and Prac

View full text Add to dashboard Cite

Indicator species need context to perform optimally for conservation purposes. If indicator potential is context‐dependent, then indicators should improve with increasing spatial‐environmental stratification. We tested this hypothesis by hierarchically stratifying a species combinations matrix (plants and wetlands) using regionalization and site typology and analyzing class specificity and occupancy rate for indicators shared across strata. Performance of indicators collectively improved with increased sample stratification providing greater spatial‐environmental context. Carefully considered sample classification schemes could strengthen the value of indicator species for monitoring biodiversity loss, environmental change, and management progress. However, the better accuracy of context‐specific indicators will have to be weighed against the practical need for fewer broad‐based indicators.

show abstract

Bioassessment in complex environments: designing an index for consistent meaning in different settings

Cited by 59 publications

References 64 publications

Tools for managing hydrologic alteration on a regional scale: Setting targets to protect stream health

Tools for managing hydrologic alteration on a regional scale: Setting targets to protect stream health

Using co‐occurrence network topology in assessing ecological stress in benthic macroinvertebrate communities

Enhanced indicator species performance with increasing contextualization

Contact Info

Product

Resources

About