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Intrafragment ecology is little studied for imperiled riverine fishes although river fragmentation and habitat loss increasingly threaten sensitive species. A long-term population-monitoring program in the Pecos River, New Mexico, provided detailed data for 15 annual cohorts of speckled chub (Macrhybopsis aestivalis), which were used to assess intrafragment patterns in recruitment and year-class strength in relation to distributional patterns, flow-regime characteristics, and air temperature. Cohorts avoided a degraded upstream reach. Age-1 and older individuals had distributions consistently centered within a central, relict-ecosystem reach that contained high-quality habitat. Age-0 individuals were widespread within the relict- ecosystem reach and a channelized reach downstream. Distributional patterns suggested that some individuals that recruited in the channelized reach dispersed upstream into relict-ecosystem habitat thereafter. One cohort always numerically dominated the population because cohorts never lived beyond 2 years. Recruitment was density-independent and predicted year-class strength. No aspect of the flow regime explained variation in recruitment. Year-class strength was consistent among cohorts because of densitydependent mortality. High-quality habitat in a centralized location, potential for dispersal between channelized and relictecosystem reaches, and diffuse distribution of pelagic-broadcast propagules throughout both reaches combined to facilitate successful annual recruitment and population persistence. L'ecologie intrafragment des poissons fluviaux en peril est peu etudiee, meme si la fragmentation des cours d'eau et la perte d'habitats menacent de plus en plus les especes sensibles. Un programme de surveillance a long terme des populations dans la riviere Pecos, au Nouveau-Mexique, a fourni des donnees detaillees sur 15 cohortes annuelles du cyprinide Macrhybopsis aestivalis, qui ont ete utilisees pour evaluer les motifs intrafragment du recrutement et de la force des classes d'age par rapport aux motifs de repartition, aux caracteristiques du regime d'ecoulement et a la temperature de l'air. Les cohortes evitaient un troncon amont degrade. Les individus d'un an et plus presentaient des repartitions uniformement centrees dans un troncon d'ecosysteme relique central renfermant des habitats de bonne qualite. Les individus de moins d'un an etaient repandus dans le troncon d'ecosysteme relique, ainsi que dans un troncon canalise situe en aval. Les motifs de repartition donnaient a penser que certains individus recrutes dans le troncon canalise se dispersaient par la suite vers l'amont dans l'habitat de l'ecosysteme relique. Il y avait toujours une cohorte dominante dans la population sur le plan du nombre puisque les cohortes ne vivaient jamais plus de 2 ans. Le recrutement etait independant de la densite et predisait la force des classes d'age. Aucun aspect du regime d'ecoulement n'expliquait les variations du recrutement. La force des classes d'age etait uniforme d'une cohorte a l'autre du au fait que la mortalite dependait de la densite. Combines, des habitats de bonne qualite dans un lieu centralise, le potentiel de dispersion entre les troncons canalise et d'ecosysteme relique et la repartition diffuse de propagules a dispersion pelagique dans les deux troncons facilitaient un recrutement annuel efficace et la persistance de la population. [Traduit par la Redaction], Introduction River fragmentation, altered streamflow regimes, and habitat loss threaten riverine fishes (Zwick 1992; Mims and Olden 2013; Hoagstrom 2015). Identification of critical habitat features is necessary to conserve imperiled [...]

Motivation: We compiled a global database of long‐term riverine fish surveys from 46 regional and national monitoring programmes and from individual academic research efforts, with which numerous basic and applied questions in ecology and global change research can be explored. Such spatially and temporally extensive datasets have been lacking for freshwater systems in comparison to terrestrial ones. Main types of variables contained: The database includes 11,386 time‐series of riverine fish community catch data, including 646,270 species‐specific abundance records, together with metadata related to the geographical location and sampling methodology of each time‐series. Spatial location and grain: The database contains 11,072 unique sampling locations (stream reach), spanning 19 countries, five biogeographical realms and 402 hydrographical basins world‐wide. Time period and grain: The database encompasses the period 1951–2019. Each time‐series is composed of a minimum of two yearly surveys (mean = 8 years) and represents a minimum time span of 10 years (mean = 19 years). Major taxa and level of measurement: The database includes 944 species of ray‐finned fishes (Class Actinopterygii). Software format: csv. Main conclusion: Our collective effort provides the most comprehensive long‐term community database of riverine fishes to date. This unique database should interest ecologists who seek to understand the impacts of human activities on riverine fish biodiversity and to model and predict how fish communities will respond to future environmental change. Together, we hope it will promote advances in macroecological research in the freshwater realm. [ABSTRACT FROM AUTHOR]

Curtis White and Allen McAfrica have a lot in common. Both are inventive, restless storytellers. Both hail from San Lorenzo, California. Both make an appearance in White's third book, The [...]