Ananda Ranasinghe - Academia.edu (original) (raw)

Papers by Ananda Ranasinghe

Marine Pollution Bulletin, 2010

Benthic indices are typically developed independently by habitat, making their incorporation into... more Benthic indices are typically developed independently by habitat, making their incorporation into large geographic scale assessments potentially problematic because of scaling inequities. A potential solution is to establish common scaling using expert best professional judgment (BPJ). To test if experts from different geographies agree on condition assessment, sixteen experts from four regions in USA and Europe were provided species-abundance data for twelve sites per region. They ranked samples from best to worst condition and classified samples into four condition (quality) categories. Site rankings were highly correlated among experts, regardless of whether they were assessing samples from their home region. There was also good agreement on condition category, though agreement was better for samples at extremes of the disturbance gradient. The absence of regional bias suggests that expert judgment is a viable means for establishing a uniform scale to calibrate indices consistently across geographic regions.

Estuaries, 2000

Associations between macrobenthic communities, measures of water column and sediment exposure, an... more Associations between macrobenthic communities, measures of water column and sediment exposure, and measures of anthropogenic activities throughout the watershed were examined for the Chesapeake Bay, U.S. The condition of the macrobenthic communities was indicated by a multimetric benthic index of biotic integrity (B-IBI) that compares deviation of community metrics from values at reference sites assumed to be minimally altered by anthropogenic sources of stress. Correlation analysis was used to examine associations between sites with poor benthic condition and measures of pollution exposure in the water column and sediment. Low dissolved oxygen events were spatially extensive and strongly correlated with benthic community condition, explaining 42% of the variation in the B-IBI. Sediment contamination was spatially limited to a few specific locations including Baltimore Harbor and the Southern Branch of the Elizabeth River and explained about 10% of the variation in the B-IBI. After removing the effects of low dissolved oxygen events, the residual variation in benthic community condition was weakly correlated with surrogates for eutrophication-water column concentrations of total nitrogen, total phosphorus, and chlorophyll a. Associations between benthic condition and anthropogenic inputs and activities in the watershed were also studied by correlation analysis. Benthic condition was negatively correlated with measures of urbanization (i.e., population density, point source loadings, and total nitrogen loadings) and positively correlated with watershed forestation. Significant correlations were observed with population density and nitrogen loading below the fall line, but not above it, suggesting that near-field activities have a greater effect on benthic condition than activities in the upper watershed. At the tributary level, the frequency of low dissolved oxygen events and levels of sediment contaminants were positively correlated with population density and percent of urban land use. Sediment contaminants were also positively correlated with point source nutrient loadings. Water column total nitrogen concentrations were positively correlated with nonpoint nutrient loadings and agricultural land use while total phosphorus concentrations were not correlated with land use or nutrient loadings. Chlorophyll a concentrations were positively correlated with nitrogen and phosphorus concentrations in the water column and with agricultural land use but were not correlated with nutrient loads.

Marine Pollution Bulletin, Feb 1, 2010

To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled ... more To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled using spatially random designs in 1994, 1998, or 2003. Benthic community condition was assessed on a fourcategory scale and the area in each category estimated. Overall, benthic macrofauna in Southern California were in good condition during 2003, with 98% of the area in reference condition or deviating only marginally. There was no evidence of disturbance near Channel Islands or small wastewater discharges, and virtually none on the mainland shelf. In contrast, bay and estuary macrofaunal communities were more frequently disturbed with nearly 13% of the area supporting disturbed benthos. The condition of the mainland shelf did not change substantially over the 9-year period, with 1.6-2.8% of the area in poor benthic condition. Southern California benthic condition evaluations may be improved by extending the depth and salinity ranges of assessment tools, and improving trend detection methods.

Integrated Environmental Assessment and Management, 2010

Data from 7 coastwide and regional benthic surveys were combined and used to assess the number an... more Data from 7 coastwide and regional benthic surveys were combined and used to assess the number and distribution of estuarine benthic macrofaunal assemblages of the western United States. Q-mode cluster analysis was applied to 714 samples and site groupings were tested for differences in 4 habitat factors (latitude, salinity, sediment grain size, and depth). Eight macrofaunal assemblages, structured primarily by latitude, salinity, and sediment grain size, were identified: (A) Puget Sound fine sediment, (B) Puget Sound coarse sediment, (C) southern California marine bays, (D) polyhaline central San Francisco Bay, (E) shallow estuaries and wetlands, (F) saline very coarse sediment, (G) mesohaline San Francisco Bay, and (H) limnetic and oligohaline. The Puget Sound, southern California, and San Francisco Bay assemblages were geographically distinct, while Assemblages E, F and H were distributed widely along the entire coast. A second Q-mode cluster analysis was conducted after adding replicate samples that were available from some of the sites and temporal replicates that were available for sites that were sampled in successive years. Variabilities due to small spatial scale habitat heterogeneity and temporal change were both low in Puget Sound, but temporal variability was high in the San Francisco estuary where large fluctuations in freshwater inputs and salinity among years leads to spatial relocation of the assemblages. Integr Environ Assess Manag 2012;8:638-648. ß 2010 SETAC Keywords: Habitat-related benthic assemblages US west coast bays estuaries Integrated Environmental Assessment and Management -Volume 8, Number 4-pp. 638-648 638 ß 2010 SETAC

The goal of the long-term benthic study in the Potomac River was to define power plants effects i... more The goal of the long-term benthic study in the Potomac River was to define power plants effects in the context of overall ecological conditions in the river, so that the ecological impacts associated with power plant operations could be assessed.

ABSTRACT The report includes species abundances of benthos collected at intervals from different ... more ABSTRACT The report includes species abundances of benthos collected at intervals from different sites of the Chesapeake Bay in Maryland.

This report includes water-quality parameters measured at intervals from surface to bottom at ben... more This report includes water-quality parameters measured at intervals from surface to bottom at benthic monitoring stations in Chesapeake Bay from April 1986 - December 1987. Species abundances are summarized by region in the study.

The report includes species abundances of benthos collected at intervals from different sites of ... more The report includes species abundances of benthos collected at intervals from different sites of the Chesapeake Bay in Maryland.

Annals of the Entomological Society of America

We report here the separate effects of larval space limitation and food limitation upon survival,... more We report here the separate effects of larval space limitation and food limitation upon survival, time of emergence, and size of adults for laboratory populations of Drosophila melanogaster Meigen (Oregon R). Increase in crowding of larvae in the absence of adequate amounts of food delayed emergence of flies, expanded the emergence period, and reduced the weight of emerging flies. In the presence of adequate larval food, space-related effects due to increased levels of larval crowding caused decreased survival to emergence and caused the total biomass to approach a relatively constant value. These results suggest that adult size is an important component of overall fitness. Apparently, the life history strategy of this fly is to decrease adult body size to a certain point when faced with food stress and then to decrease survival rate so that body size can remain large enough for mating and oviposition.

This report presents data collected in the fourth year of a five-year study to assess long-term r... more This report presents data collected in the fourth year of a five-year study to assess long-term responses of benthic communities to changes in water quality resulting from Bay-wide clean-up efforts, and to assess the short- and long-term responses of the benthos to power-plant operations. The results of preliminary comparisons of the data with patterns identified after the first three years are also presented. The report is organized into two volumes. Volume I contains the text and summary findings as follows: July 1984 to August 1988 water-quality data, July 1984 to April 1988 sediment and taxonomic data, and July 1984 to June 1987 production and biomass data. Tables and figures were included at the end of each chapter in Volume I. Volumes II consist of Appendices A through T which contain data gathered between January 1987 and August 1988 and are supplementary to data submitted in previous data summary reports.

California and the World Ocean '02, 2005

Coastal Monitoring through Partnerships, 2003

Studies designed to measure anthropogenic impacts on marine benthic communities depend on the abi... more Studies designed to measure anthropogenic impacts on marine benthic communities depend on the ability of taxonomists to consistently discriminate, identify, and count benthic organisms. To quantify errors and discrepancies in identification and enumeration, 20 samples were completely reprocessed by another one of four participating laboratories. Errors were detected in 13.0% of the data records, affecting total abundance by 2.1%, numbers of taxa by 3.4%, and identification accuracy by 4.7%. Paired t-tests were used to test for differences in the Benthic Response Index (BRI), total abundance, numbers of taxa, and the Shannon-Wiener index between the original and the reanalysis data. Differences in the BRI were statistically insignificant. Although statistically significant differences were observed for numbers of taxa, total abundance, and the Shannon-Wiener index, the differences were small in comparison to the magnitude of differences typically observed between anthropogenically affected and reference sites.

Ecological Indicators, 2015

The AZTI Marine Biotic Index (AMBI) requires less geographically-specific calibration than other ... more The AZTI Marine Biotic Index (AMBI) requires less geographically-specific calibration than other benthic indices, but has not performed as well in US coastal waters as it has in the European waters for which it was originally developed. Here we examine the extent of improvement in index performance when the Ecological Group (EG) classifications on which AMBI is based are derived using local expertise. Twentythree US benthic experts developed EG scores for each of three regions in the United States, as well as for the US as a whole. Index performance was then compared using: (1) EG scores specific to a region, (2) national EG scores, (3) national EG scores supplemented with standard international EG scores for taxa that the US experts were not able to make assignments, and (4) standard international EG scores. Performance of each scheme was evaluated by diagnosis of condition at pre-defined good/bad sites, concordance with existing local benthic indices, and independence from natural environmental gradients. The AMBI performed best when using the national EG assignments augmented with standard international EG values. The AMBI using this hybrid EG scheme performed well in differentiating apriori good and bad sites (>80% correct classification rate) and AMBI scores were both concordant and correlated (r s = 0.4-0.7) with those of existing local indices. Nearly all of the results suggest that assigning the EG values in the framework of local biogeographic conditions produced a better-performing version of AMBI. The improved index performance, however, was tempered with apparent biases in score distribution. The AMBI, regardless of EG scheme, tended to compress ratings away from the extremes and toward the moderate condition and there was a bias with salinity, where high quality sites received increasingly poorer condition scores with decreasing salinity.

The goal of the long-term benthic study in the Potomac River was to define power plants effects i... more The goal of the long-term benthic study in the Potomac River was to define power plants effects in the context of overall ecological conditions in the river, so that the ecological impacts associated with power plant operations could be assessed.

PLoS ONE, 2012

DNA barcoding, as it is currently employed, enhances use of marine benthic macrofauna as environm... more DNA barcoding, as it is currently employed, enhances use of marine benthic macrofauna as environmental condition indicators by improving the speed and accuracy of the underlying taxonomic identifications. The next generation of barcoding applications, processing bulk environmental samples, will likely only provide presence information. However, macrofauna indices presently used to interpret these data are based on species abundances. To assess the importance of this difference, we evaluated the performance of the Southern California Benthic Response Index (BRI) and the AZTI Marine Biotic Index (AMBI) when species abundance data were removed from their calculation. Presence only versions of these two indices were created by eliminating abundance weighting while preserving species identity. Associations between the presence and abundance BRI, and the presence and abundance AMBI were highly significant, with correlation coefficients of 0.99 and 0.81, respectively. The presence versions validated almost equally to the abundance-based indices when applied to the spatial and the temporal monitoring data used to validate the original indices. Simulations in which taxa were systematically removed from calculation of the indices were also conducted to assess how large the barcode library must be for the indices to be effective. Correlation between the BRI-P and BRI remained above 0.9 with only 370 species in the library and reducing the number of species to 450 had almost no effect on correlation between the presence and abundance versions of the AMBI.

Marine Pollution Bulletin, 1997

Marine Pollution Bulletin, 2009

Many types of indices have been developed to assess benthic invertebrate community condition, but... more Many types of indices have been developed to assess benthic invertebrate community condition, but there have been few studies evaluating the relative performance of different index approaches. Here we calibrate and compare the performance of five indices: the Benthic Response Index (BRI), Benthic Quality Index (BQI), Relative Benthic Index (RBI), River Invertebrate Prediction and Classification System (RIVPACS), and the Index of Biotic Integrity (IBI). We also examine whether index performance improves when the different indices, which rely on measurement of different properties, are used in combination. The five indices were calibrated for two geographies using 238 samples from southern California marine bays and 125 samples from polyhaline San Francisco Bay. Index performance was evaluated by comparing index assessments of 35 sites to the best professional judgment of nine benthic experts. None of the individual indices performed as well as the average expert in ranking sample condition or evaluating whether benthic assemblages exhibited evidence of disturbance. However, several index combinations outperformed the average expert. When results from both habitats were combined, two four-index combinations and a three-index combination performed best. However, performance differences among several combinations were small enough that factors such as logistics can also become a consideration in index selection.

Marine Pollution Bulletin, 2009

During the last decade, there have been substantial scientific advances in the development of ind... more During the last decade, there have been substantial scientific advances in the development of indices that measure the condition of biological ecosystem elements in coastal and estuarine waters. Though successful, these advances were only the initial steps and a special session on use of indices in ecological integrity assessments was held at the Coastal and Estuarine Research Federation meeting to focus the field on the most appropriate directions for the next decade. The session identified four primary scientific challenges: (i) reduce the array of indices by identifying the index approaches that are most widely successful; (ii) establish minimum criteria for index validation; (iii) intercalibrate methods to achieve uniform assessment scales across geographies and habitats; and (iv) integrate indices across ecosystem elements. Where an explosion of indices characterized the last decade, the next decade needs to be characterized by consolidation. With increased knowledge and understanding about the strengths and weaknesses of competing index approaches, the field needs to unify approaches that provide managers with the simple answers they need to use ecological condition information effectively and efficiently.

Marine Pollution Bulletin, 2010

To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled ... more To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled using spatially random designs in 1994, 1998, or 2003. Benthic community condition was assessed on a fourcategory scale and the area in each category estimated. Overall, benthic macrofauna in Southern California were in good condition during 2003, with 98% of the area in reference condition or deviating only marginally. There was no evidence of disturbance near Channel Islands or small wastewater discharges, and virtually none on the mainland shelf. In contrast, bay and estuary macrofaunal communities were more frequently disturbed with nearly 13% of the area supporting disturbed benthos. The condition of the mainland shelf did not change substantially over the 9-year period, with 1.6-2.8% of the area in poor benthic condition. Southern California benthic condition evaluations may be improved by extending the depth and salinity ranges of assessment tools, and improving trend detection methods.

Marine Pollution Bulletin, 2010

Benthic indices are typically developed independently by habitat, making their incorporation into... more Benthic indices are typically developed independently by habitat, making their incorporation into large geographic scale assessments potentially problematic because of scaling inequities. A potential solution is to establish common scaling using expert best professional judgment (BPJ). To test if experts from different geographies agree on condition assessment, sixteen experts from four regions in USA and Europe were provided species-abundance data for twelve sites per region. They ranked samples from best to worst condition and classified samples into four condition (quality) categories. Site rankings were highly correlated among experts, regardless of whether they were assessing samples from their home region. There was also good agreement on condition category, though agreement was better for samples at extremes of the disturbance gradient. The absence of regional bias suggests that expert judgment is a viable means for establishing a uniform scale to calibrate indices consistently across geographic regions.

Estuaries, 2000

Associations between macrobenthic communities, measures of water column and sediment exposure, an... more Associations between macrobenthic communities, measures of water column and sediment exposure, and measures of anthropogenic activities throughout the watershed were examined for the Chesapeake Bay, U.S. The condition of the macrobenthic communities was indicated by a multimetric benthic index of biotic integrity (B-IBI) that compares deviation of community metrics from values at reference sites assumed to be minimally altered by anthropogenic sources of stress. Correlation analysis was used to examine associations between sites with poor benthic condition and measures of pollution exposure in the water column and sediment. Low dissolved oxygen events were spatially extensive and strongly correlated with benthic community condition, explaining 42% of the variation in the B-IBI. Sediment contamination was spatially limited to a few specific locations including Baltimore Harbor and the Southern Branch of the Elizabeth River and explained about 10% of the variation in the B-IBI. After removing the effects of low dissolved oxygen events, the residual variation in benthic community condition was weakly correlated with surrogates for eutrophication-water column concentrations of total nitrogen, total phosphorus, and chlorophyll a. Associations between benthic condition and anthropogenic inputs and activities in the watershed were also studied by correlation analysis. Benthic condition was negatively correlated with measures of urbanization (i.e., population density, point source loadings, and total nitrogen loadings) and positively correlated with watershed forestation. Significant correlations were observed with population density and nitrogen loading below the fall line, but not above it, suggesting that near-field activities have a greater effect on benthic condition than activities in the upper watershed. At the tributary level, the frequency of low dissolved oxygen events and levels of sediment contaminants were positively correlated with population density and percent of urban land use. Sediment contaminants were also positively correlated with point source nutrient loadings. Water column total nitrogen concentrations were positively correlated with nonpoint nutrient loadings and agricultural land use while total phosphorus concentrations were not correlated with land use or nutrient loadings. Chlorophyll a concentrations were positively correlated with nitrogen and phosphorus concentrations in the water column and with agricultural land use but were not correlated with nutrient loads.

Marine Pollution Bulletin, Feb 1, 2010

To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled ... more To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled using spatially random designs in 1994, 1998, or 2003. Benthic community condition was assessed on a fourcategory scale and the area in each category estimated. Overall, benthic macrofauna in Southern California were in good condition during 2003, with 98% of the area in reference condition or deviating only marginally. There was no evidence of disturbance near Channel Islands or small wastewater discharges, and virtually none on the mainland shelf. In contrast, bay and estuary macrofaunal communities were more frequently disturbed with nearly 13% of the area supporting disturbed benthos. The condition of the mainland shelf did not change substantially over the 9-year period, with 1.6-2.8% of the area in poor benthic condition. Southern California benthic condition evaluations may be improved by extending the depth and salinity ranges of assessment tools, and improving trend detection methods.

Integrated Environmental Assessment and Management, 2010

Data from 7 coastwide and regional benthic surveys were combined and used to assess the number an... more Data from 7 coastwide and regional benthic surveys were combined and used to assess the number and distribution of estuarine benthic macrofaunal assemblages of the western United States. Q-mode cluster analysis was applied to 714 samples and site groupings were tested for differences in 4 habitat factors (latitude, salinity, sediment grain size, and depth). Eight macrofaunal assemblages, structured primarily by latitude, salinity, and sediment grain size, were identified: (A) Puget Sound fine sediment, (B) Puget Sound coarse sediment, (C) southern California marine bays, (D) polyhaline central San Francisco Bay, (E) shallow estuaries and wetlands, (F) saline very coarse sediment, (G) mesohaline San Francisco Bay, and (H) limnetic and oligohaline. The Puget Sound, southern California, and San Francisco Bay assemblages were geographically distinct, while Assemblages E, F and H were distributed widely along the entire coast. A second Q-mode cluster analysis was conducted after adding replicate samples that were available from some of the sites and temporal replicates that were available for sites that were sampled in successive years. Variabilities due to small spatial scale habitat heterogeneity and temporal change were both low in Puget Sound, but temporal variability was high in the San Francisco estuary where large fluctuations in freshwater inputs and salinity among years leads to spatial relocation of the assemblages. Integr Environ Assess Manag 2012;8:638-648. ß 2010 SETAC Keywords: Habitat-related benthic assemblages US west coast bays estuaries Integrated Environmental Assessment and Management -Volume 8, Number 4-pp. 638-648 638 ß 2010 SETAC

The goal of the long-term benthic study in the Potomac River was to define power plants effects i... more The goal of the long-term benthic study in the Potomac River was to define power plants effects in the context of overall ecological conditions in the river, so that the ecological impacts associated with power plant operations could be assessed.

ABSTRACT The report includes species abundances of benthos collected at intervals from different ... more ABSTRACT The report includes species abundances of benthos collected at intervals from different sites of the Chesapeake Bay in Maryland.

This report includes water-quality parameters measured at intervals from surface to bottom at ben... more This report includes water-quality parameters measured at intervals from surface to bottom at benthic monitoring stations in Chesapeake Bay from April 1986 - December 1987. Species abundances are summarized by region in the study.

The report includes species abundances of benthos collected at intervals from different sites of ... more The report includes species abundances of benthos collected at intervals from different sites of the Chesapeake Bay in Maryland.

Annals of the Entomological Society of America

We report here the separate effects of larval space limitation and food limitation upon survival,... more We report here the separate effects of larval space limitation and food limitation upon survival, time of emergence, and size of adults for laboratory populations of Drosophila melanogaster Meigen (Oregon R). Increase in crowding of larvae in the absence of adequate amounts of food delayed emergence of flies, expanded the emergence period, and reduced the weight of emerging flies. In the presence of adequate larval food, space-related effects due to increased levels of larval crowding caused decreased survival to emergence and caused the total biomass to approach a relatively constant value. These results suggest that adult size is an important component of overall fitness. Apparently, the life history strategy of this fly is to decrease adult body size to a certain point when faced with food stress and then to decrease survival rate so that body size can remain large enough for mating and oviposition.

This report presents data collected in the fourth year of a five-year study to assess long-term r... more This report presents data collected in the fourth year of a five-year study to assess long-term responses of benthic communities to changes in water quality resulting from Bay-wide clean-up efforts, and to assess the short- and long-term responses of the benthos to power-plant operations. The results of preliminary comparisons of the data with patterns identified after the first three years are also presented. The report is organized into two volumes. Volume I contains the text and summary findings as follows: July 1984 to August 1988 water-quality data, July 1984 to April 1988 sediment and taxonomic data, and July 1984 to June 1987 production and biomass data. Tables and figures were included at the end of each chapter in Volume I. Volumes II consist of Appendices A through T which contain data gathered between January 1987 and August 1988 and are supplementary to data submitted in previous data summary reports.

California and the World Ocean '02, 2005

Coastal Monitoring through Partnerships, 2003

Studies designed to measure anthropogenic impacts on marine benthic communities depend on the abi... more Studies designed to measure anthropogenic impacts on marine benthic communities depend on the ability of taxonomists to consistently discriminate, identify, and count benthic organisms. To quantify errors and discrepancies in identification and enumeration, 20 samples were completely reprocessed by another one of four participating laboratories. Errors were detected in 13.0% of the data records, affecting total abundance by 2.1%, numbers of taxa by 3.4%, and identification accuracy by 4.7%. Paired t-tests were used to test for differences in the Benthic Response Index (BRI), total abundance, numbers of taxa, and the Shannon-Wiener index between the original and the reanalysis data. Differences in the BRI were statistically insignificant. Although statistically significant differences were observed for numbers of taxa, total abundance, and the Shannon-Wiener index, the differences were small in comparison to the magnitude of differences typically observed between anthropogenically affected and reference sites.

Ecological Indicators, 2015

The AZTI Marine Biotic Index (AMBI) requires less geographically-specific calibration than other ... more The AZTI Marine Biotic Index (AMBI) requires less geographically-specific calibration than other benthic indices, but has not performed as well in US coastal waters as it has in the European waters for which it was originally developed. Here we examine the extent of improvement in index performance when the Ecological Group (EG) classifications on which AMBI is based are derived using local expertise. Twentythree US benthic experts developed EG scores for each of three regions in the United States, as well as for the US as a whole. Index performance was then compared using: (1) EG scores specific to a region, (2) national EG scores, (3) national EG scores supplemented with standard international EG scores for taxa that the US experts were not able to make assignments, and (4) standard international EG scores. Performance of each scheme was evaluated by diagnosis of condition at pre-defined good/bad sites, concordance with existing local benthic indices, and independence from natural environmental gradients. The AMBI performed best when using the national EG assignments augmented with standard international EG values. The AMBI using this hybrid EG scheme performed well in differentiating apriori good and bad sites (>80% correct classification rate) and AMBI scores were both concordant and correlated (r s = 0.4-0.7) with those of existing local indices. Nearly all of the results suggest that assigning the EG values in the framework of local biogeographic conditions produced a better-performing version of AMBI. The improved index performance, however, was tempered with apparent biases in score distribution. The AMBI, regardless of EG scheme, tended to compress ratings away from the extremes and toward the moderate condition and there was a bias with salinity, where high quality sites received increasingly poorer condition scores with decreasing salinity.

The goal of the long-term benthic study in the Potomac River was to define power plants effects i... more The goal of the long-term benthic study in the Potomac River was to define power plants effects in the context of overall ecological conditions in the river, so that the ecological impacts associated with power plant operations could be assessed.

PLoS ONE, 2012

DNA barcoding, as it is currently employed, enhances use of marine benthic macrofauna as environm... more DNA barcoding, as it is currently employed, enhances use of marine benthic macrofauna as environmental condition indicators by improving the speed and accuracy of the underlying taxonomic identifications. The next generation of barcoding applications, processing bulk environmental samples, will likely only provide presence information. However, macrofauna indices presently used to interpret these data are based on species abundances. To assess the importance of this difference, we evaluated the performance of the Southern California Benthic Response Index (BRI) and the AZTI Marine Biotic Index (AMBI) when species abundance data were removed from their calculation. Presence only versions of these two indices were created by eliminating abundance weighting while preserving species identity. Associations between the presence and abundance BRI, and the presence and abundance AMBI were highly significant, with correlation coefficients of 0.99 and 0.81, respectively. The presence versions validated almost equally to the abundance-based indices when applied to the spatial and the temporal monitoring data used to validate the original indices. Simulations in which taxa were systematically removed from calculation of the indices were also conducted to assess how large the barcode library must be for the indices to be effective. Correlation between the BRI-P and BRI remained above 0.9 with only 370 species in the library and reducing the number of species to 450 had almost no effect on correlation between the presence and abundance versions of the AMBI.

Marine Pollution Bulletin, 1997

Marine Pollution Bulletin, 2009

Many types of indices have been developed to assess benthic invertebrate community condition, but... more Many types of indices have been developed to assess benthic invertebrate community condition, but there have been few studies evaluating the relative performance of different index approaches. Here we calibrate and compare the performance of five indices: the Benthic Response Index (BRI), Benthic Quality Index (BQI), Relative Benthic Index (RBI), River Invertebrate Prediction and Classification System (RIVPACS), and the Index of Biotic Integrity (IBI). We also examine whether index performance improves when the different indices, which rely on measurement of different properties, are used in combination. The five indices were calibrated for two geographies using 238 samples from southern California marine bays and 125 samples from polyhaline San Francisco Bay. Index performance was evaluated by comparing index assessments of 35 sites to the best professional judgment of nine benthic experts. None of the individual indices performed as well as the average expert in ranking sample condition or evaluating whether benthic assemblages exhibited evidence of disturbance. However, several index combinations outperformed the average expert. When results from both habitats were combined, two four-index combinations and a three-index combination performed best. However, performance differences among several combinations were small enough that factors such as logistics can also become a consideration in index selection.

Marine Pollution Bulletin, 2009

During the last decade, there have been substantial scientific advances in the development of ind... more During the last decade, there have been substantial scientific advances in the development of indices that measure the condition of biological ecosystem elements in coastal and estuarine waters. Though successful, these advances were only the initial steps and a special session on use of indices in ecological integrity assessments was held at the Coastal and Estuarine Research Federation meeting to focus the field on the most appropriate directions for the next decade. The session identified four primary scientific challenges: (i) reduce the array of indices by identifying the index approaches that are most widely successful; (ii) establish minimum criteria for index validation; (iii) intercalibrate methods to achieve uniform assessment scales across geographies and habitats; and (iv) integrate indices across ecosystem elements. Where an explosion of indices characterized the last decade, the next decade needs to be characterized by consolidation. With increased knowledge and understanding about the strengths and weaknesses of competing index approaches, the field needs to unify approaches that provide managers with the simple answers they need to use ecological condition information effectively and efficiently.

Marine Pollution Bulletin, 2010

To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled ... more To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled using spatially random designs in 1994, 1998, or 2003. Benthic community condition was assessed on a fourcategory scale and the area in each category estimated. Overall, benthic macrofauna in Southern California were in good condition during 2003, with 98% of the area in reference condition or deviating only marginally. There was no evidence of disturbance near Channel Islands or small wastewater discharges, and virtually none on the mainland shelf. In contrast, bay and estuary macrofaunal communities were more frequently disturbed with nearly 13% of the area supporting disturbed benthos. The condition of the mainland shelf did not change substantially over the 9-year period, with 1.6-2.8% of the area in poor benthic condition. Southern California benthic condition evaluations may be improved by extending the depth and salinity ranges of assessment tools, and improving trend detection methods.