The Journal of the North American Benthological Society (J-NABS) is celebrating its 25^th anniversary with a special issue composed of review papers that address the progress of 18 subdisciplines within benthology and the role of the Journal in the development of each subdiscipline. The objectives of our paper were to define the underlying reasons for publishing the Journal by discussing the role of scientific journals, provide a brief history of the Journal, discuss the challenges and opportunities presented by the rapid evolution of scholarly publication, and provide a synopsis of the papers in this issue. J-NABS is a highly respected journal within the areas of ecology and marine and freshwater biology. The Journal is most similar to Freshwater Biology and Fundamental and Applied Limnology based on citation patterns. Changes in scientific publishing have created significant opportunities and challenges for the Journal. Digital information technologies and the World Wide Web have changed the way people seek, read, and use information; created opportunities to reach a global audience and to facilitate free and open exchange of information; and created a need among society-published journals for new business models as traditional revenue sources (individual and library subscriptions) continue to decline. The scope of J-NABS is habitat specific and most papers in the Journal address some aspect of stream ecology. Papers published in this anniversary issue of J-NABS fall into subdisciplines in 5 broad categories: 1) the physical environment (5 articles); 2) the interface of chemistry and biology (2 articles); 3) the biota (7 articles); 4) the human factor (4 articles); and 5) a synthesis. Many authors in this issue call for benthologists to find ways to apply their work to manage, conserve, and restore aquatic habitats and organisms.

The disciplines of geomorphology, hydrology, and hydrogeology have had a marked influence on the evolution of systems thinking in stream ecology. The River Continuum Concept was an explicit attempt to “translate the energy equilibrium theory from the physical system of geomorphologists into a biological analog” (Vannote et al. 1980, p. 131). A subsequent view of rivers as corridors evolved from an improved understanding of hydrologic linkages between rivers and their catchments and among channels, alluvial aquifers, and riparian zones/floodplains. More recently, the importance of channel network topology and dynamic, 3-dimensional hydrologic connectivity across fluvial landscapes has been emphasized by stream ecologists. This progression of ecological thinking provides a useful framework for understanding the role of fluvial geomorphology, channel hydrology, and hyporheic hydrology in shaping fundamental concepts of stream ecosystem science. This progression also defines a trajectory for understanding the potential role of the nascent discipline of stream hydrogeomorphology in contributing to an improved understanding of ecological responses to a stream's dynamic physical template. Although grounded in the discipline of stream ecology, J-NABS has contributed substantively to our understanding of interdisciplinary linkages among ecology, geomorphology, hydrology, and hydrogeology and, therefore, is well positioned as an outlet for ecologically based contributions to advances in stream hydrogeomorphology.

Over the last 25 y, stream ecosystem theory has expanded to include explicitly the vertical dimension of surface–groundwater linkages via the hyporheic zone and below alluvial floodplains. Hydrological exchange between the stream and hyporheic zone mediates transport of products from the biogeochemical activities within the sediments. Hot-spots of primary productivity in the surface stream often result from upwelling nutrient-rich water. Conversely, downwelling surface water supplies organic matter and dissolved O₂ to hyporheic invertebrates and microbes, enhancing hyporheic productivity. Many of the papers seminal to conceptual and empirical advances in hyporheic research have been published in J-NABS, reflecting stream benthologists' awareness of the relevance of processes and biota in the hyporheic zone. However, major research gaps remain. One is the need for further empirical data to test the predictions of several current conceptual frameworks that hypothesize conditions under which the hyporheic zone might be expected to contribute most to surface stream metabolism, especially in large rivers with shallow alluvial aquifers. A second is how to apply research findings about the functional significance of the hyporheic zone to river restoration and conservation. Many activities that restore or protect surface biota and habitats probably benefit hyporheic processes and fauna as well, but this prediction should be tested. Last, hyporheic exchange and the biogeochemical processes within the sediments occur across multiple hierarchical spatial scales, but we are yet to understand fully these interactions or to extrapolate successfully across scales. J-NABS should continue to play a significant role in publishing research on the hyporheic zone and extend the scope to include applications in river and floodplain management and restoration.

We summarized landscape approaches used in the study of freshwater ecosystems, updated recent literature reviews on interactions between terrestrial and lotic ecosystems, and discussed the influence of J-NABS on developments in the field. We focused primarily on studies of freshwater ecosystems done at or above the catchment scale. Special issues of J-NABS and other journals have advanced our understanding of the effects of spatially distributed characteristics and phenomena on aquatic ecosystems. Topics that have been well covered in J-NABS include use of classification to predict biotic assemblages and impacts of human disturbance (especially urbanization) on stream structure and function. Early work focused on correlative relationships between landscape variables and various biotic components of stream systems, whereas later studies addressed causal linkages between landscape and biota, including landscape effects on hydrology, habitat at various spatial scales, and ecosystem processes. At large spatial scales (i.e., catchments or regions), landscape context and heterogeneity are important predictors of compositional, structural, and functional attributes of streams and lakes. The size of the study region and catchments and the level of disturbance across the region can interfere with our ability to generalize results across studies. Geographical information systems and remote sensing technologies are important tools for understanding and quantifying these relationships, and new sophisticated tools are available for measuring landscape pattern and context. Lotic ecosystems are challenging to study because of the directional flow of water across (and beneath) the landscape. However, new spatial analysis tools can incorporate hydrologic connectivity. Limited data on surface and groundwater connections and lack of available watershed delineations make finding similar connections between lakes and wetlands and their surrounding landscapes challenging.

We reviewed the development of ideas and empirical understanding about disturbance in lotic ecosystems by providing a pre-1986 historic context and highlighting major themes that have emerged in the 25 y since the inception of J-NABS. Disturbance was not well incorporated into stream ecological thinking before 1986, but awareness of its significance began to emerge in the early 1980s, as demonstrated by the publication of several classic papers illustrating the ecological consequences of floods. Broad recognition of disturbance as a fundamental driver in streams was crystallized by Resh et al. (1988⁴) in a paper that marked the beginning of a period of intense research on disturbance. We recognized 4 subsequent research themes: 1) definition of terms and concepts and development of tools for quantifying disturbances and ecological responses, 2) the disturbance renaissance, a period during which empirical research increased dramatically, 3) formalization of the significance of disturbance in streams by its incorporation into conceptual models of stream ecosystems, and 4) operationalization of disturbance for management and restoration of streams and rivers. Despite remarkable progress toward understanding disturbance in lotic ecosystems in the past 25 y, opportunities for future research are numerous. Increasing scope and intensity of human activities underscore the need to examine interactions among disturbances and to incorporate ecological principles into management and restoration activities. New insights are likely to arise from recognition of links between geomorphic forms and processes and the ecology of disturbance. Viewing streams in the context of regime shifts should also lead to new advances, particularly for restoration, because disturbances can elicit nonlinear responses. Successes in these efforts should contribute to improved scientific understanding and stewardship of streams and rivers.

We reviewed concepts of patch dynamics and environmental heterogeneity and their applications to the study of fluvial ecosystems, with emphasis on research published in J-NABS. We discuss several important papers synthesizing theories and findings on this topic and reports of descriptive and experimental research. A large body of research, much of it published in J-NABS, has demonstrated how spatial and temporal variation influences population, community, and ecosystem patterns and processes in fluvial ecosystems. Conceptual models of patch dynamics can be traced to 2 basic approaches: 1) the landscape ecology perspective and 2) the metacommunity perspective. The former focuses on how spatial patterns are created and affect ecological processes over variable scales of space and time, whereas the latter emphasizes the important influence of periodic disturbances, refugia, and dispersal in maintaining nonequilibrium communities within patch mosaics. The origin of the metacommunity Patch Dynamics Concept can be traced to G. Evelyn Hutchinson's ideas about nonequilibrium communities, and a key contribution was Townsend's (1989⁴) J-NABS review of the Patch Dynamics Concept in stream community ecology. The study of fluvial ecosystem ecology from a patch-dynamics landscape perspective is well represented by empirical studies published in J-NABS, but some emerging topics remain little studied, including: 1) experiments designed to test predictions of the Patch Dynamics Concept of metacommunities vs alternative models; 2) empirical documentation of patch dynamics and their effects on ecological processes across longitudinal, lateral, and temporal gradients; 3) the influence of species' life-history attributes on community dynamics in relation to habitat characteristics and aspects of disturbance; and 4) the manner in which landscape patterns, patch dynamics, and metacommunity dynamics affect foodweb patterns and processes.

Nutrient dynamics in streams has been an important topic of research since the 1960s. Here we review this topic and the significant role played by J-NABS in its development. We limit this review almost exclusively to studies of N and P because these elements have been shown to limit productivity in streams. We use the expression nutrient dynamics for studies that included some measures of biological processes occurring within streams. Prior to the 1970s, instream biological processes were little studied, but through 1985 conceptual advances were made, and 4 types of studies made important contributions to our understanding of instream processes: 1) evidence of increased plant production and decomposition in response to nutrient addition, 2) studies showing a downstream decrease in nutrient concentrations, 3) studies using radioisotopes, and 4) budget studies. Beginning with the first paper printed in its first issue, J-NABS has been the outlet for key papers advancing our understanding of rates and controls of nutrient dynamics in streams. In the first few years, an important review and a conceptual model for conducting experiments to study nutrient dynamics in streams were published in J-NABS. In the 1990s, J-NABS published a number of papers on nutrient recycling within algal communities, the role of the hyporheic zone, the role of spawning fish, and the coupling of data from field ¹⁵N additions and a N-cycling model to provide a synoptic view of N dynamics in streams. Since 2000, J-NABS has published influential studies on nutrient criteria for streams, rates of and controls on nitrification and denitrification, uptake of stream nutrients by riparian vegetation, and nutrient dynamics in urban streams. Nutrient dynamics will certainly continue to be an important topic in J-NABS. Topics needing further study include techniques for studying nutrient dynamics, nutrient dynamics in larger streams and rivers, the ultimate fate of nutrients taken up by plants and microbes in streams, ecological stoichiometry, the effects of climate change, and the role of streams and rivers in nutrient transformation and retention at the landscape scale.

The role of allochthonous organic matter in lotic ecosystems has been an important research topic among aquatic ecologists since the seminal work by Lindeman was published in 1942. Since 1986, studies on organic matter budgets, ecosystem metabolism, and decomposition published in J-NABS have made significant contributions to the overall understanding of organic matter dynamics in streams. In this review, we summarize the utility of organic matter budgets, cover the major advances in research on ecosystem metabolism, and describe the intrinsic and extrinsic factors influencing organic matter decomposition. We also discuss future directions and current applications of research and highlight the need for additional studies on the role of land use and climate change, as well as continued use of organic matter processing as a functional metric in biomonitoring studies. We emphasize the need for continued data synthesis into comprehensive organic matter budgets. Such comparative studies can elucidate important drivers of organic matter dynamics and can assist in the understanding of large continental/global changes that might be occurring now and in the near future. In general, continued emphasis on synthesizing information into a larger framework for streams and rivers will improve our overall understanding of the importance of organic matter in lotic ecosystems.

Systematics, or taxonomy, is the study of the diversity of life on Earth. Its goals are to discover and describe new biological diversity and to understand its evolutionary and biogeographic origins and relationships. Here we review the contributions to the field of systematics and taxonomy published over the last 25 y in J-NABS and its predecessor Freshwater Invertebrate Biology (FIB). We examined a total of 64 studies that we considered to be largely taxonomic in nature. We classified these studies into 2 major categories: morphological (e.g., descriptive taxonomy, taxonomic revisions) and molecular (e.g., deoxyribonucleic acid [DNA] barcoding, population genetics). We examined studies in 5-y increments for J-NABS. We also studied the period 1982 to 1985, during which FIB was published. On average, 12 taxonomic studies were published within each 5-y period. Molecular studies first appeared in 1986 and have slowly increased, reaching their greatest number within the last 5 y. Studies also were classified by their individual attributes. Morphological studies were, by far, the most common, but studies also included molecular data, biological information, distributional data, keys, and biogeographical analyses. Most studies included >1 of these attributes. Overall, the role of J-NABS in the development of benthic taxonomy has been minimal in terms of number of publications, but as part of the nexus of taxomonic literature, all contributions have been important to the discipline. We discuss these contributions and their impact on the following subject areas: taxonomy and revisionary systematics, phylogenetic and molecular systematics, taxonomic resources, taxonomic resolution, conservation and taxonomy, professional training, taxonomic certification, and graduate education. We also give an overview of new developments in the taxonomists' toolbox. These developments include DNA barcoding, online taxonomic resources, digital identification keys, cybertaxonomy, and modern museum collections and resources.

Microbes play numerous roles in stream ecosystems. They carry out key processes in stream nutrient cycles and are responsible for a large part of organic matter breakdown. Advances over the past 25 y in our understanding of which microbes are linked to specific processes have been rapid and fundamental, in part, because of improvements in methods. It is now clear that immobilization of inorganic nutrients and other transformations are just as important as release of nutrients during organic matter decomposition. Microbial biomass is recognized as a key portion of trophic transfer, but our understanding of the pathways of connection have changed. Information on the actual composition of microbial communities is very recent, and it is still unclear whether there are consistent biogeographic patterns in freshwater bacterial composition. One of the major areas of potential advancement is clarifying the linkage between microbial community composition and ecosystem function. Determining the strength of the connection between microbial assemblage composition and the processes they catalyze remains a technical and conceptual hurdle. Quantifying the strength of this linkage seems necessary to understand variability in both composition and function because feedbacks are likely in cases where the link is strong. The future of the field is bright, but we need to understand how microbes and the processes they carry out will respond to climate change and novel stream management approaches.

The presence, abundance, composition, and growth of periphyton are controlled or influenced by 5 broad classes of environmental variation: disturbances, stressors, resources, hydraulic conditions, and biotic interactions. In turn, periphyton communities affect water chemistry, hydraulic conditions, habitat availability, and foodweb dynamics. This review focuses on responses of periphyton communities to environmental variation. A specific objective of the review is to identify robust periphyton–environment relationships and insightful concepts. Contributors to J-NABS have led the field in testing and expanding concepts in periphyton ecology. J-NABS papers about periphyton patch dynamics, light- and nutrient-limited periphyton growth, and the effects of disturbances on periphyton structure and function have been particularly influential. However, many topics in periphyton ecology remain unexplored and underexplored. These topics include resource colimitation, physiological responses to stressors, allelopathy, competitive inhibition and exclusion, and the effects of drag forces and turbulence. Periphyton ecology studies in J-NABS tend to be multivariable, phenomenological, and nonmechanistic. Such studies provide information about temporal and spatial patterns, but rarely provide evidence for the causes of those patterns. These studies are often impaired by low statistical power and insufficient experimental control. Periphyton ecology needs more rigorous manipulative experiments, particularly experiments that generate clear relationships between environmental drivers and ecological responses.

Life-history research has a long tradition in benthic biology because of its value in explaining patterns observed in nature, quantifying trophic relationships and energetics, and interpreting experimental results. We examined articles published in the Journal of the North American Benthological Society (J-NABS) during a 23-y period (volumes 5–27) to determine trends in life-history research and to assess future needs in these types of studies. Of the 9 life-history elements we examined, growth and mortality of benthic macroinvertebrates were most commonly reported in the 412 J-NABS studies containing ≥1 of these elements. Recruitment and dormancy were the least-studied elements, and development, reproduction, dispersal, voltinism, and phenology were intermediate. Most of these studies were based on aquatic insects, especially Ephemeroptera and Trichoptera, and mollusks (particularly bivalves). Detailed life histories of single species published in J-NABS have averaged ∼1/volume, with most studies being on Ephemeroptera, Plecoptera, Trichoptera, and Odonata. Both detailed life-history studies and studies containing life-history elements have declined over time, especially when considered as a percentage of articles published in J-NABS. In a timeline of important developments in life-history studies, 4 time periods or themes were evident: 1) an emphasis on descriptive natural history, which was the earliest type of ecological research conducted and which extended into the 1970s; 2) synthesis of life-history information in books and review articles, which was most prevalent in the 1970s and 1980s; 3) adoption of functional-feeding groups as a measure of trophic status of benthic organisms, which began in the 1970s and continues through today; and 4) the use of a species-trait approach to examine both basic and applied aspects of benthic biology, which began in the 1990s, is an expanding research area, and is a valuable application of life-history information. Life-history research has been published more often in specialized proceedings and regional journals than in J-NABS. Clearly more life-history research is needed, but time, logistical considerations, and funding constraints restrict professional benthologists from conducting this kind of research. Perhaps anglers and those participating in volunteer monitoring groups can be encouraged to conduct studies to provide this needed information.

We summarized studies on the impacts and scale effects of negative (competition, predation, parasitism, herbivory) and positive (mutualism, commensalism, indirect facilitation) species interactions in freshwater benthic habitats since ∼1986 and focused on organisms with mainly or entirely aquatic life cycles. Benthologists publishing in J-NABS have contributed robustly to our overall knowledge of predation and herbivory but less so of other species interactions. Predators can limit the abundance of benthic prey and affect prey size or age structure, behavior, and morphology, and these effects can be transmitted through food webs and ecosystems. Herbivores can limit biomass of benthic algae, alter physiognomy, species composition and diversity, and stoichiometry, and exert strong indirect effects within food webs and nutrient cycles. Parasites can alter host behavior or morphology, but few studies have shown that lethal/sublethal effects of parasites on their hosts have population- or community-scale consequences. Fishes and macroinvertebrates occasionally experience competition, but the effect of competition on demographies and assemblages appears restricted to local scales, perhaps because competition can be modulated by many biotic (bioenergetic efficiency, parasitism, predation) and abiotic (floods, drought, resource distribution) factors. Positive interactions have been the least studied species interaction by benthologists, but interest is growing. Future study of population-scale positive interactions and nontraditional interactions at larger scales (e.g., riparian effects on benthic habitat stabilization, cross-system recruitment of different life stages) will improve our understanding of freshwater benthic ecosystems and their conservation. We urge benthologists to explore how populations evolve in response to biotic interactions embedded in benthic communities and to assess how these responses might redefine trophic and community structure and their emergent properties.

Aquatic ecosystems are almost invariably connected to other ecosystems because the dominant force of water movement facilitates physical, chemical, and biological exchanges among ecosystems. In this sense, we define an ecosystem linkage as any persistent or recurring process or attribute that connects different ecosystems in some manner. We argue that such linkages are integral, even defining, components of aquatic ecosystem structure and function, and therefore, should be evaluated in the course of ecological studies. J-NABS has made significant contributions to our understanding of such linkages. The percentage of all publications in J-NABS addressing some ecological linkage has approached 10% in recent years. Historically, emphasis was placed on upstream–downstream linkages in flowing waters, and theory (e.g., river continuum, nutrient spiraling) has evolved largely around this phenomenon. However, other linkages among ecosystems have received increased attention in the past 20 y. These linkages include surface–subsurface, lake–stream, river–floodplain, and, more recently, marine–freshwater. We contend that many ecological processes, including primary production, nutrient cycling, organic matter processing, and secondary production, are driven by such exchanges because of the donor-controlled nature of many aquatic ecosystems. Exchanges of materials from aquatic ecosystems to terrestrial systems, caused by flooding, nutrient translocation, or insect emergence, can be substantial. Movement of energy and nutrients from the ocean to freshwaters, such as in the migrations of anadromous fishes, also can be dramatic. Despite increasing evidence of the importance of such linkages, considerable impediments to research, such as journal specialization, lack of interdisciplinary study teams, and limited funding of sufficient duration for such research, exist. Such obstacles are surmountable if investigators continue to emphasize that aquatic ecology will be advanced by the study of such linkages, and that environmental problems are better understood and solved in the context of that knowledge.

Invertebrate secondary production, or the formation of invertebrate biomass through time, has been estimated in many freshwater benthic habitats. It has been a major research theme for the North American Benthological Society (NABS), and many of its members have made significant contributions to the subject, both before and during the existence of J-NABS. Although some benthic production work occurred before 1960, the major methods were developed primarily during the 1960s and 1970s. Most of these methods also were applied in terrestrial and marine environments. The main focus of our paper is how secondary production has been used as an essential variable in facilitating answers to a wide variety of ecological questions. Benthic freshwater production studies before the inception of J-NABS were primarily related to life history, interpopulation comparisons, niche overlap/competition, predator–prey relationships, differences in production/biomass (P/B), energy flow, the trophic basis of production, habitat-specific microdistributions, effects of pollution and dams, and quantification of aquatic–terrestrial linkages. Since that time, new applications have been related to habitat-specific macrodistributions, quantitative food webs, experimental and tracer-based studies of trophic resources, chemical flows/stoichiometric relationships, diversity/function relationships, influence of nonnative species and landuse changes, implications of metabolic theory, and the importance of meiofauna vs macrofauna. J-NABS has been a major outlet for many of these applications, has probably included a higher fraction of papers incorporating secondary production analysis than any other journal, and probably will continue to be a leader in this area.

Effective ecosystem management in the face of human alterations depends on our ability to quantify ecologically significant changes and to discriminate among impact levels and types. We reviewed the literature on biological responses of freshwater biota to human disturbances over the last century. Many of the main methods for assessing ecological integrity originated in Europe [e.g., Saprobien Index, Trent Biotic Index, Biological Monitoring Working Party, River InVertebrate Prediction And Classification System, multiple traits] or in North America [e.g., Index of Biotic Integrity, leaf-litter breakdown, functional feeding groups]. We used bibliometric data to detail the contribution of J-NABS to developments in assessment of ecological integrity. A total of 225 bioassessment articles were published in J-NABS from 1986 to 2007. This total was ∼½ of the number of bioassessment articles published over the same period in Freshwater Biology (FWB; another leading freshwater journal used for comparison), but the proportion of bioassessment articles in the 2 journals was similar (∼20%). The proportion of bioassessment articles in J-NABS has increased over the last 25 y. This trend indicates the growing interest in the topic and the delay (∼30 y since the Clean Water Act) of scientific action in response to water legislation. Taxonomic composition and multivariate techniques, multimetric indices, lotic systems, macroinvertebrates, land use, and overall human impacts were major themes in J-NABS bioassessment articles. Progress in bioassessment is needed in 3 main areas. First, bioassessments done at large spatial scales are needed to meet requirements of new environmental policies. Second, bioassessment should shift from consideration of taxon losses to losses of ecological functions. Third, statistical techniques are needed for predictive assessment of deviation in ecological integrity between expected (natural) and observed (natural or impacted) conditions. Assessment of functional integrity based on multiple traits is a promising area because biological traits represent universal biological characteristics that are connected to ecosystem functions. However, the relationships between ecophysiological traits of individuals and ecosystem-scale responses must be properly defined for specific types of human impairment, and utility of the approach for routine bioassessments applied by managers must be tested.

Benchmarks provide context and are a critical element of all ecological assessments. Over the last 25 y, hundreds of papers have been published on various aspects of ecological assessments, and most of the analyses described in these papers depend on specifying an ecological benchmark for context. Freshwater scientists and managers usually use reference sites (typically sites in natural or least-disturbed condition) to assess the ecological conditions at other sites. Accurate and precise assessments require that assessed sites be matched with appropriate reference conditions. Two general types of approaches have been proposed to predict reference conditions: classifications based on natural environmental settings and models that use continuously variable environmental attributes as inputs. Two types of classifications have been examined: geographic-dependent regionalizations based on general landscape features and geographic-independent typologies that are typically based on combinations of regional and channel features. We examined >1000 papers that addressed some aspect of predicting the reference condition in freshwater ecosystems. We focused on 5 types of benchmarks: ecological, thermal, hydrologic, geomorphic, and chemical. Our review showed that over the last 25 y, researchers have developed increasingly sophisticated methods that can be used to predict reference conditions. Most disciplines have increasingly moved toward site-specific modeling approaches as a way to improve both accuracy and precision of predictions, although typological approaches dominate geomorphic characterizations. Papers published in J-NABS have been especially important in advancing and refining methods for predicting ecological benchmarks. Much of the progress made in the science of ecological assessment emerged from research that advanced our understanding of how the spatial and temporal distributions of freshwater biota are related to naturally occurring environmental features and how those relationships can be most accurately and precisely described and predicted. Thus, the performance of ecological assessments is critically linked to how well we characterize freshwater environments, and research in the watershed sciences that addresses predicting thermal, hydrologic, geomorphic, and chemical attributes of freshwater ecosystems has paralleled research focused on predicting biota. We anticipate that knowledge produced from future collaborations between ecologists and watershed scientists coupled with the application of modern modeling techniques will largely determine progress in characterizing and predicting biota–environment relationships and, thus, the accuracy and precision of future ecological assessments.

Freshwater habitats occupy <1% of the Earth's surface, yet are hotspots that support ∼10% of all known species, and ∼⅓ of vertebrate species. Fresh waters also are hotspots for human activities that have led to widespread habitat degradation, pollution, flow regulation and water extraction, fisheries overexploitation, and alien species introductions. These impacts have caused severe declines in the range and abundance of many freshwater species, so that they are now far more imperiled than their marine or terrestrial counterparts. Here, we review progress in conservation of freshwater biodiversity, with a focus on the period since 1986, and outline key challenges for the future. Driven by rising conservation concerns, freshwater ecologists have conducted a great deal of research over the past 25 y on the status, trends, autecology, and propagation of imperiled species, threats to these species, the consequences of biodiversity loss for ecosystem functioning, metapopulation dynamics, biodiversity hotspots, reserve design, habitat restoration, communication with stakeholders, and weaknesses of protective legislation. Nevertheless, existing efforts might be insufficient to stem the ongoing and coming multitude of freshwater extinctions. We briefly discuss 4 important challenges for freshwater conservation. First, climate change will imperil both freshwater species and human uses of fresh water, driving engineering responses that will further threaten the freshwater biota. We need to anticipate both ecological and human responses to climate change, and to encourage rational and deliberate planning of engineering responses to climate change before disasters strike. Second, because freshwater extinctions are already well underway, freshwater conservationists must be prepared to act now to prevent further losses, even if our knowledge is incomplete, and engage more effectively with other stakeholders. Third, we need to bridge the gap between freshwater ecology and conservation biology. Fourth, we suggest that scientific societies and scholarly journals concerned with limnology or freshwater sciences need to improve their historically poor record in publishing important papers and influencing practice in conservation ecology. Failure to meet these challenges will lead to the extinction or impoverishment of the very subjects of our research.

Growing awareness of environmental degradation resulted in stricter environmental regulations and laws for aquatic ecosystems. These regulations were followed by an increase in applied research and monitoring beginning in the early 1970s. The number of applied scientists who were members of the North American Benthological Society grew at a commensurate rate. The editors of J-NABS recognized that, despite these increases, submitted manuscripts mostly addressed basic science. In response, the BRIDGES section of J-NABS was created in 1994 to provide a forum for linking basic ecological principles to applied science problems and issues. We examined the emergence of applied science topics in J-NABS and its predecessor, Freshwater Invertebrate Biology, from their beginning in 1982 to 2009. We classified papers among 11 categories that included a basic/applied science linkage. In the 1980s, applied papers were predominantly on effects of eutrophication/pollution and landuse changes. When BRIDGES was established in 1994, papers were solicited by editors and BRIDGES sections usually included >1 paper on a common theme to express complementary or alternate viewpoints. Forty-two papers appeared in BRIDGES between 1994 and 2009, but the number per issue declined after 2001. The total number of applied science papers in J-NABS has increased since ∼1994. Citation analysis of BRIDGES papers illustrates how information is being cited, but applied papers often are used in ways that might not lead to citations. BRIDGES transitioned to a new format in September 2009 to address new types of complex, multifaceted linkages. All new BRIDGES articles will be open access, and authors will be encouraged to produce lay-language fact sheets and to post them on the web.

The year 2010 marks the 25^th anniversary of publication of the Journal of the North American Benthological Society (J-NABS). To highlight the occasion, we solicited 18 contributions, classified into: 1) physical environment, 2) interface of chemistry and biology, 3) biota, and 4) human factor, to review how subdisciplines within the general field of benthology have changed. We identified 7 major themes across the 18 contributions. First, articles dealing with biota were published with the greatest number in J-NABS over the past 25 y, but an increasing number of papers address the human factor and the chemical/biological interface. A 2^nd theme was the value of special issues and series, which have resulted in greater visibility and attention for selected topics. Three of the 7 themes could be loosely classified as focusing on emerging or future trends: 3) the role of new technologies and methods in advancing benthic science, 4) the growing importance of multidisciplinary approaches to tackling problems, and 5) convergence by different disciplines on key research topics, such as trait-based indices, spatial heterogeneity, and nonlinear behavior of ecosystems. The 6^th theme was the apparent insularity within stream ecology, which could be reduced by increased borrowing from and contributing to general ecological theory. Last, many contributions trumpeted a call to action, calling on practitioners to put benthic science into practice. Directions identified for potentially fruitful future research included new technologies; multidisciplinary research; and emerging stressors, such as pharmaceuticals, climate change, and urban runoff. We conclude by recommending a transition to more solution-based research and by recognizing that the volume of new information being generated creates both opportunities and challenges for the future.