Michael T. Barbour

Condition of stream ecosystems in the US: an overview of the first national assessment

Abstract The Wadeable Streams Assessment (WSA) provided the first statistically sound summary of the ecological condition of streams and small rivers in the US. Information provided in the assessment filled an important gap in meeting the requirements of the US Clean Water Act. The purpose of the WSA was to: 1) report on the ecological condition of all wadeable, perennial streams and rivers within the conterminous US, 2) describe the biological condition of these systems with direct measures of aquatic life, and 3) identify and rank the relative importance of chemical and physical stressors affecting stream and river condition. The assessment included perennial wadeable streams and rivers that accounted for 95% of the length of flowing waters in the US. The US Environmental Protection Agency, states, and tribes collected chemical, physical, and biological data at 1392 randomly selected sites. Nationally, 42% of the length of US streams was in poor condition compared to best available reference sites in their ecoregions, 25% was in fair condition, and 28% was in good condition. Results were reported for 3 major regions: Eastern Highlands, Plains and Lowlands, and West. In the West, 45% of the length of wadeable flowing waters was in good condition. In the Eastern Highlands, only 18% of the length of wadeable streams and rivers was in good condition and 52% was in poor condition. In the Plains and Lowlands, almost 30% of the length of wadeable streams and rivers was in good condition and 40% was in poor condition. The most widespread stressors observed nationally and in each of the 3 major regions were N, P, riparian disturbance, and streambed sediments. Excess nutrients and excess streambed sediments had the highest impact on biological condition; streams scoring poor for these stressors were at 2 to 3× higher risk of having poor biological condition than were streams that scored in the good range for the same stressors.

Measuring the attainment of biological integrity in the USA: a critical element of ecological integrity

The concept of ecological integrity has become a worldwide phenomenon and is firmly entrenched into the regulatory structure of environmental law in the United States of America (USA). The attainment of ecological integrity requires the attainment of its three elements: physical, chemical, and biological integrity. In the USA, measures of chemical integrity were implemented first into monitoring programs and were effective in reducing pollutant loadings to the nation’s surface waters. Because biological communities integrate the effects of different Stressors such as reduced oxygen, excess nutrients, toxic chemicals, increased temperature, excessive sediment loading, and habitat degradation, the advent of bioassessment in regulatory programs has provided a more comprehensive and effective monitoring and assessment strategy. Measures of biological integrity clearly have become a priority in the USA. The development of biological criteria (biocriteria) within regulatory programs to serve as thresholds by which to judge the attainment of designated aquatic life conditions of surface waters is a major focus of states and Indian tribes within the USA. The derivation of reference conditions for the nation’s surface waters (i. e., streams, rivers, lakes, wetlands, estuaries, and marine waters) across different physiographic regions is a critical element in the design of biocriteria and is currently a primary initiative in the USA. Nearly all state water resource agencies have developed bioassessment approaches for streams; 1600 to 75 000 km of streams require assessment in each state. Bioassessment development for other water body types is not as advanced to date. The US Environmental Protection Agency (USEPA) has produced technical guidance for developing effective bioassessment programs; they include crucial elements such as defining objectives, classifying water bodies according to expected biological attributes, deriving the reference condition of the site classes, developing standardized protocols for sampling and data analysis, and implementing a quality assurance plan. Approaches to bioassessment in the USA follow a basic design of incorporating various attributes of the elements and processes of the aquatic community, which is either an aggregation into a multimetric index or a series of multivariate analyses using the attributes as input variables. The Clean Water Act of 1972 and its subsequent amendments mandate maintaining, restoring, and protecting the ecological integrity of surface waters. Through use of robust bioassessments and other measures of ecological integrity, the USA has developed a strategic plan to establish priorities to meet this goal.

Apples, oranges, and ecoregions: on determining pattern in aquatic assemblages

Classification of waterbodies is a necessary step for aquatic biological assessment. Geographic classes, such as physiographic provinces, marine biogeographic provinces, and ecoregions are frequently used as a classification framework for conducting bioassessments. An alternative to such a priori classification of waterbodies is to let the biological data tell us, using various statistical exploratory techniques to identify classes that do not necessarily conform to geographic stratification. In assessment of new sites, it is often necessary to identify or predict which of several classes the new site may belong to. We classified benthic macroinvertebrate assemblages from streams of Wyoming, using 3 alternative methods: a priori establishment of ecoregions, adaptive modification of the ecoregions, and a posteriori clustering. Classification strengths were compared using similarity dendrograms. Clustering separated the sites better than ecoregions, but the clusters showed strong ecoregional affinities. The modified ecoregions were equal to the clusters in classification strength. We conclude that an iterative process that includes generation of hypotheses, exploratory data analysis, and evaluation and modification of hypotheses is most likely to produce robust classifications, regardless of specific analytical approaches used.

Characterizing and Comparing Bioassessment Methods and Their Results: A Perspective

Most of the many bioassessment methods currently in use in the United States produce data of unknown quality. The results are: 1) uncertainty as to which methods yield accurate information for a given type of site, and 2) missed opportunities to share data among different programs or organizations having potentially comparable methods and data quality. Using a performance-based methods system (PBMS) and benthic macroinvertebrate assessment methods as examples, we offer a framework for characterizing the data quality achieved by a collection-and-analysis method and for determining the comparability of different methods. This framework incorporates 3 steps that: 1) quantify method precision and bias for a single site, using different field personnel and different site classes; 2) quantify method precision, bias, and performance range using multiple reference sites within at least 2 different site classes; and 3) quantify method sensitivity, bias, performance range, and--indirectly--accuracy, using test sites (with different levels or types of probable impairment) as well as reference sites. Comparability of methods is judged by the degree of similarity in their performance characteristics rather than in their respective scores or metric values. The PBMS framework could yield several benefits including: documentation of personnel training in the field; realistic requirements for data quality in bioassessment methods so that information gathered is likely to meet program or project needs; greater flexibility in choice of method used; refinement of methods by agencies responsible for long-term monitoring without the loss of historical data; and more sharing of bioassessment information across political boundaries, thus reducing duplication of efforts.

A multi-agency comparison of aquatic macroinvertebrate-based stream bioassessment methodologies

Abstract Sharing ecological data can increase the amount of information available to state and federal agencies to manage water resources. Because state agencies in the US use different methods to assess biological water quality, the quality and comparability of data must be understood before data can be shared. The documentation of data quality objectives and performance characteristics has been recommended as a way to compare biological data collected using different methods. To address this issue, five state agencies conducted a pilot study on methods comparability and performance characteristics of their methods and assessments (i.e. precision and sensitivity) at two streams located in the coastal plain of the southeastern US. Taxa richness and North Carolina Biotic Index (NCBI) results were not directly comparable among agencies using different sample processing, collection, and analysis methods, although these results often produced similar site rankings. Comparison of performance characteristics across methods suggested that assessment information could be shared among some agencies despite differences in methods and metric results.

Development of rapid bioassessment approaches using benthic macroinvertebrates for Thai streams.

Thailand currently lacks formal bioassessment approaches and protocols to assist management decisions for water quality. The aim of this research is to develop a practical method of rapid bioassessment for a professional level by using benthic macroinvertebrate assemblages for streams in Thailand. Eleven reference and nine test sites were sampled in the headwater streams of the Loei River and adjacent areas to explore the development of a practical protocol. Specific physico-chemical parameters were selected to provide ecological information supplemental to the biological indicators. The biological research was designed around the USEPA Rapid Bioassessment Protocols (RBPs) using the multi-habitat approach. Four fixed-count subsamplings (100, 200, 300 and 500 organisms) were randomly conducted using a standardized gridded pan to evaluate an appropriate level for bioassessment in Thai streams. A 300 organism subsample is adequate for bioassessment purposes in Thai stream (evaluated by calculating dissimilarity values and ordination techniques). A systematic selection of candidate reference sites, metric selection, and index calibration was part of this research. Multimetric and multivariate analyses were examined as a foundation for bioassessment in Thailand. The multimetric approach appears to be more practical for a rapid bioassessment technique. Nine core metrics were identified for biological index score including number of total taxa, Diptera taxa, Ephemeroptera, Plecoptera, Trichoptera, and Coleoptera taxa, (%) Plecoptera, (%) Tolerant organisms, Beck’s Biotic Index, (%) Intolerant organisms, Shredders taxa and Clingers taxa were calibrated for the final index. As a result of multimetric and multivariate analyses, family level identification data effectively discriminated reference condition and broad-scale environmental gradients. Hampered by incomplete taxonomic knowledge of benthic macroinvertebrates in Thailand, family-level identification may be sufficient taxonomic resolution for rapid bioassessment in Thailand.

Adding value to water resource management through biological assessment of rivers

Water resource management encompasses a variety of regulations and mandates relevant to water protection and restoration. Awareness of the value-added biological monitoring and assessment to water resource management is increasing worldwide, but especially in countries that have implemented proactive water law and regulatory frameworks for protection of surface waters. Biological communities provide an integrated response to pollutants and human disturbance within watersheds through their continuous exposure to the magnitude, duration, and frequency of stressors, and, thus, are important for assessing ecosystem health. The selection of proper bioindicators can provide additional benefits through their use in causal analysis of impaired waters and measurement of ecosystem recovery after restoration. A process for implementing biological indicators in a monitoring and assessment framework is outlined for managers and practitioners of water resource protection and restoration.

Critical technical elements of state bioassessment programs: a process to evaluate program rigor and comparability

We developed a systematic process to evaluate state/tribal bioassessment programs to provide information about the rigor of the technical approach. This is accomplished via on-site interviews to produce an evaluation that assigns one of four levels of rigor as an outcome. Level 4 is the most rigorous and reflects a technical capacity to accurately determine incremental condition and support management programs. The remaining three levels are less able to assess incremental condition and are appropriate for only some management support needs. Accurately determining impairment and diagnosing pollution-specific stressors are fundamental tasks that states/tribes must accomplish to provide management support. This goal is fulfilled to varying degrees by most states/tribes. The evaluation employs a checklist and a sliding scale of rigor for 13 technical elements. Feedback is provided to each state/tribe via a technical memorandum that describes the technical components of the monitoring program, highlights strengths, and recommends improvements for specific technical issues. This can be used to refine the bioassessment and monitoring programs to better support management programs. The results of 14 state/tribal evaluations are included here. The majority (nine states, one tribe) revealed that most operate at level 2 with developmental activities that will elevate the level of program rigor already underway. Two states operate level 4 programs and each have numeric biocriteria and refined designated uses in their water quality standards. This is the ultimate goal of the process of engaging states in the development of bioassessment programs in the U.S.

Implications of global change for the maintenance of water quality and ecological integrity in the context of current water laws and environmental policies.

There is both a fundamental and applied need to define expectations of changes in aquatic ecosystems due to global changes. It is clear that programs using biological indicators and reference-based comparisons as the foundation for assessments are likely to make increasingly erroneous decisions if the impacts of global change are ignored. Global changes influence all aspects of water resource management decisions based on comparisons to reference conditions with impacts making it increasingly problematic to find an “undisturbed” water body to define acceptable conditions of ecological integrity. Using a more objective scale for characterizing reference conditions that is anchored in expectations for what would be attainable under undisturbed conditions, such as the Biological Condition Gradient (BCG) is one approach that maintains consistent definitions for ecosystem conditions. In addition, protection of reference stations and of unique or undisturbed aquatic resources is imperative, though the scope of protection options is limited. Projections indicate that encroaching land use will affect 36–48% of current reference surface waters by the year 2100. The interpretation of biological indicators is also at risk from global changes. Distinguishing taxonomic attributes based on temperature or hydrologic preferences can be used to enhance the ability to make inferences about global change effects compared to other stressors. Difficulties arise in categorizing unique indicators of global changes, because of similarities in some of the temperature and hydrologic effects resulting from climate change, land use changes, and water removal. In the quest for biological indicators that might be uniquely sensitive to one global stressor as an aid in recognizing probable causes of ecosystem damage, the potential similarities in indicator responses among global and landscape-scale changes needs to be recognized as a limiting factor. Many aspects of global changes are not tractable at the local to regional scales at which water quality regulations are typically managed. Our ability to implement water policies through bioassessment will require a shift in the scale of assessment, planning, and adaptations in order to fulfill our ultimate regulatory goals of preserving good water quality and ecological integrity. Providing clear expectations of effects due to global change for key species and communities in freshwater ecosystems will help water quality programs achieve their goals under changing environmental conditions.

Perspective: Communicating our science to influence public policy

Abstract We ask 3 questions that bear on the ability of aquatic scientists to influence public perceptions and public policy related to important environmental issues: 1) Why should scientists become better communicators? 2) What can we do to promote effective communication? 3) How can scientific societies help scientists meet this communication challenge? Shareholders in the environment include watershed groups, environmental interest groups, water-quality agencies, the general public, and the scientific community. These shareholders often are not professional scientists, but they influence the formation of natural resource policies. Individual aquatic scientists should be able to explain their science to other shareholders in a way that disabuses misconceptions of scientific principles, fosters informed dialogue concerning actions that affect aquatic ecosystems, and prevents poor decisions that can result from inaccurate information or short-sightedness. Scientific societies can effectively communicate the concerns of individual scientists by: 1) articulating the links between basic research and ecological principles to applied science, thereby building the foundation of science needed to support informed decision-making; 2) translating and disseminating results of scientific research to nonscientists to minimize inaccuracies, thereby fostering scientific literacy; and 3) taking proactive positions that promote infusion of sound science into policy debates on pressing environmental issues, especially those that bear on freshwater ecosystems.