Conserving native biodiversity in the face of human-and climate-related impacts is a challenging and globally important ecological problem that requires an understanding of spatially connected, organismal-habitat relationships. Globally, a suite of disturbances (e.g., agriculture, urbanization, climate change) degrades habitats and threatens biodiversity. A mosaic approach (in which connected, interacting collections of juxtaposed habitat patches are examined) provides a scientific foundation for addressing many disturbance-related, ecologically based conservation problems.For example, if specific habitat types disproportionately increase biodiversity, these keystones should be incorporated into research and management plans. Our sampling of fish biodiversity and aquatic habitat along ten 3-km sites within the Upper Neosho River subdrainage, KS, from June-August 2013 yielded three generalizable ecological insights. First, specific types of mesohabitat patches (i.e., pool, riffle, run, and glide) were physically distinct and created unique mosaics of mesohabitats that varied across sites. Second, species richness was higher in riffle mesohabitats when mesohabitat size reflected field availability. Furthermore, habitat mosaics that included more riffles had greater habitat diversity and more fish species. Thus, riffles (<5% of sampled area) acted as keystone habitats. Third, additional conceptual development, which we initiate here, can broaden the identification of keystone habitats across ecosystems and further operationalize this concept for research and conservation. Thus, adopting a mosaic approach can increase scientific understanding of organismal-habitat relationships, maintain natural biodiversity, advance spatial ecology, and facilitate effective conservation of native biodiversity in human-altered ecosystems.

Nutrient releases and spiraling metrics are frequently used to quantify the downstream transport of nutrients and to better understand the effects of anthropogenic inputs to downstream waters. Ambient uptake rates in streams can be measured through stable isotope enrichments, while pulse and plateau additions can estimate such rates via extrapolation and modeling techniques, respectively. Data from these releases can be used to estimate ambient uptake rates from nutrient additions and possibly determine the functional relationships between nutrient concentrations and uptake rates. Here, we compared estimated ambient rates calculated from established pulse and plateau approaches, results obtained from new modeling approaches, and rates at ambient concentrations from stable isotope enrichments. Comparative releases of NH 4 Cl and 15 NH 4 Cl were conducted in four experimental reaches across the grassland Kings Creek and urban Campus Creek, KS. Nutrient uptake was predominantly linear with increasing ammonium. Estimated ambient uptake rates varied among sites, release methods, and data analysis approaches.However, plateau ambient rates from new modeling approaches matched closely with measured ambient rates from isotope enrichments at three sites, suggesting that modeled plateau data may be best for a first look at determining nutrient uptake rates at an individual site. Limitations and benefits of each approach vary; however, baseflow discharge may be a key driver when choosing a method. If possible, multiple methods should be attempted at each location and under each novel set of conditions to determine the best approach prior to designing and implementing a more extensive series of measurements.

Conserving native biodiversity depends on restoring functional habitats in the face of human-induced disturbances. Low-head dams are a ubiquitous human impact that degrades aquatic ecosystems worldwide. To improve our understanding of how low-head dams impact habitat and associated biodiversity, our research examined complex interactions among three spheres of the total environment. i.e., how low-head dams (anthroposphere) affect aquatic habitat (hydrosphere), and native biodiversity (biosphere) in streams and rivers. Creation of lake-like habitats upstream of low-head dams is a well-documented major impact of dams. Alterations downstream of low head dams also have important consequences, but these downstream dam effects are more challenging to detect. In a multidisciplinary field study at five dammed and five undammed sites within the Neosho River basin, KS, we tested hypotheses about two types of habitat sampling (transect and mosaic) and two types of statistical analyses (analysis of covariance and path analysis). We used fish as our example of biodiversity alteration. Our research provided three insights that can aid environmental professionals who seek to conserve and restore fish biodiversity in aquatic ecosystems threatened by human modifications. First, a mosaic approach identified habitat alterations below low-head dams (e.g. increased proportion of riffles) that were not detected using the more commonly-used transect sampling approach. Second, the habitat mosaic approach illustrated how low-head dams reduced natural variation in stream habitat. Third, path analysis, a statistical approach that tests indirect effects, showed how dams, habitat, and fish biodiversity interact. Specifically, path analysis revealed that low-head dams increased the proportion of riffle habitat below dams, and, as a result, indirectly increased fish species richness. Furthermore, the pool habitat that was created above low-head dams dramatically decreased fish species richness. As we show here, mosaic habitat sampling and path analysis can help conservation practitioners improve science-based management plans for disturbed aquatic systems worldwide.

Citation: Fencl, J. S., M. E. Mather, J. M. Smith, and S. M. Hitchman. 2017. The blind men and the elephant examine biodiversity at low-head dams: Are we all dealing with the same dam reality? Ecosphere 8(11):e01973. 10. 1002/ecs2.1973 Abstract. Dams are ubiquitous environmental impacts that threaten aquatic ecosystems. The ability to compare across research studies is essential to conserve the native biodiversity that is impacted by the millions of low-head dams that currently fragment streams and rivers. Here, we identify a previously unaddressed obstacle that impedes this generalization. Specifically, divergent spatial and taxonomic approaches that result from different conceptualizations of the dam-biodiversity problem can produce conflicting sciencebased conclusions about the same dam impact. In this research, using the same dammed and undammed sites, we evaluated the scientific generality of different conceptualizations of the dam-biodiversity problem. We compared two different but commonly used spatial approaches-(1) above dam-below dam vs.(2) undammed-dammed comparisons-and 11 different, commonly used taxonomic approaches (three assemblage summaries, eight guilds). Sites above the dam structure had less diverse fish assemblages than sites below dams, whereas sites below the dam structure were similar to undammed sites. Thus, spatial approach 1 detected a large dam effect and spatial approach 2 detected a small dam effect. Similarly, some taxonomic responses (species richness, diversity, abundance, and number of guilds) detected large dam effects; other responses detected small (riffle specialist guild) or no dam effects (pool generalists). In summary, our results showed that how the problem was framed altered scientific conclusions and created different dam realities. The metaphor of how individual blind men disagree about the structure of an elephant, based on examinations of different body parts, reinforces the need for a coordinated, holistic perspective on dam research. Although no single approach is adequate for all problems, identifying the form, consequences of, and relationships among different research conceptualizations will set the stage for future syntheses of dam-biodiversity research to advance science-based conservation.

Identifying sources of larval production and subsequent dispersal paths is critical for evaluating the efficacy of marine protected areas. We assessed whether the Cowcod Conservation Area (CCA), the largest oceanic reserve in the Southern California Bight (SCB), established to conserve cowcod Sebastes levis, protects essential spawning habitat of another overfished rockfish, bocaccio S. paucispinis. To this end we investigated relationships between age-specific (recently hatched, preflexion and postflexion) larval distribution and abundance, environmental indicators (temperature, chlorophyll a), and depth between 2002 and 2004. Larval presence was consistently higher in the CCA than in surrounding areas of the SCB. Abundances of bocaccio larvae from all size classes peaked in 2004, which had relatively low sea surface temperature and high chlorophyll a. Depth and sea surface temperature or chlorophyll a were significantly related to the presence of recently hatched larvae, which were most common in cooler western CCA waters where chlorophyll a tended to be highest. In contrast, later stage larvae were not significantly related to depth, indicating that they had been advected from natal locations. Examination of current patterns and the distribution of older larvae suggested that the direction of larval transport varied among years, with mostly northwestward transport in 2002, a cyclonic recirculation feature that may have retained larvae within the CCA in 2003, and southwestward transport in 2004. These results demonstrate that spatial and temporal oceanographic heterogeneity affect larval distribution and transport in this region. We conclude that the CCA protects essential bocaccio spawning habitat and is an important source of bocaccio production in the SCB. KEY WORDS: Depth · Essential fish habitat · Larval fish · Marine protected area · Larval pro duction Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 465: [227][228][229][230][231][232][233][234][235][236][237][238][239][240][241][242] 2012 To have a positive impact on sustainable fisheries, it is critical that MPAs serve as a source of larval production (Pelc et al. 2009). Ideally, high production within a reserve will both replenish the population within the reserve through local larval retention and provide a continuously renewable resource that is available to the fishery by seeding adjoining areas through larval dispersal. Despite the dependence of MPA efficacy on larval production, direct measurements of larval output within reserves are scarce (but see Watson et al. 2002, Thompson et al. 2012, and reserve boundaries are typically established without quantification of spatial or temporal patterns of larval production. In this study, we explored how larval production of the overfished rockfish, bocaccio Sebastes paucispinis, varied through time and space within and around the largest marine reserve in California, USA, the Cowcod Conservation Area (CCA).Although many MPAs have been recently e...