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Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities.

Background: The characterization and influence of preoperative health care use on quality-of-care indicators (e.g., readmissions) has received limited attention in populations with musculoskeletal disorders. The purpose of this study was to characterize preoperative health care use and examine its effect on quality-of-care indicators among patients undergoing elective surgery for osteoarthritis. Methods: Data on health care use for 124,750 patients with elective surgery for osteoarthritis in Ontario, Canada, from April 1, 2015 to March 31, 2018 were linked across health administrative databases. Using total health care use one-year previous to surgery, patients were grouped from low to very high users. We used Poisson regression models to estimate rate ratios, while examining the relationship between preoperative health care use and quality-of-care indicators (e.g., extended length of stay, complications, and 90-day hospital readmissions). We controlled for covariates (age, sex, neighborhood income, rural/urban residence, comorbidities, and surgical anatomical site). Results: We found a statistically significant trend of increasing worse outcomes by health care use gradients that persisted after controlling for patient demographics and comorbidities. Findings were consistent across surgical anatomical sites. Moreover, very high users have relatively large numbers of visits to non-musculoskeletal specialists. Conclusions: Our findings highlight that information on patients' preoperative health care use, together with other risk factors (such as comorbidities), could help decision-making when benchmarking or reimbursing hospitals caring for complex patients undergoing surgery for osteoarthritis. [ABSTRACT FROM AUTHOR]

Reservoir creation often leads to a 'trophic upsurge' of nutrients that may affect communities living near impoundments. We determined the duration of the nutrient upsurge and associated changes in plankton in a study of a new reservoir (Lake 979; L979) in northwestern Ontario that included 2 years pre-impoundment, 16 years of impoundment, and 2 years postimpoundment. Secondarily, we determined allochthonous versus autochthonous carbon (C) use by zooplankton with reservoir development. For the first 6-14 years of impoundment, mean concentrations of total phosphorus (TP), total nitrogen (TN), and dissolved organic carbon increased 3.6, 2.4, and 1.7 times above pre-impoundment levels, respectively, decreasing thereafter. L979 shifted from a net sink to a source of TP and TN for the first 6 years of impoundment. Mean annual biomasses of bacteria, phytoplankton, and zooplankton increased 4.6,17, and 32.6 times above pre-impoundment levels, respectively, with associated changes in community composition. Bacteria and phytoplankton returned to pre-impoundment levels within 4 and 10 years, respectively, but zooplankton densities remained elevated even after 18 years. Changes in [[delta].sup.13]C suggested that postim poundment zooplankton biomass was not supported predominantly by allochthonous C. La creation d'un reservoir entraine souvent une<< flambee trophique >>de nutriments qui peut avoir une incidence sur les communautes vivant pres des ouvrages de retenue. Nous avons determine la duree de la flambee de nutriments et de changements associes dans le plancton dans le cadre de l'etude d'un nouveau reservoir (lac 979; L979) dans le Nord-Ouest de l'Ontario, portant sur 2 annees avant, 16 annees durant, et 2 annees apres la retenue des eaux. En deuxieme lieu, nous avons determine l'utilisation de carbone (C) allochtone et autochtone par le zooplancton selon l'etat du reservoir. Pour les 6 a 14 premieres annees de retenue, les concentrations moyennes de phosphore total (TP), d'azote total (TN), et de carbone organique dissous sont passees, respectivement, a 3,6,2,4, et 1,7 fois les concentrations pre-retenue, pour diminuer par la suite. De puits net, le reservoir L979 est devenu une source en ce qui concerne le TP et le TN pour les 6 premieres annees de retenue. Les biomasses annuelles moyennes de bacteries, de phytoplancton, et de zooplancton sont passees, respectivement, a 4,6,17, et 32,6 fois les valeurs pre-retenue, avec les modifications en decoulant a la composition des communautes. Les bacteries et le phytoplancton etaient retournes a leurs niveaux pre-retenue apres 4 et 10 ans, respectivement, mais les densites de zooplancton demeuraient elevees apres 18 ans. Les modifications du [[delta].sup.13]C donnent a penser que la biomasse de zooplancton apres la retenue n'etait pas supportee principalement par du C allochtone. [Traduit par la Redaction], Introduction Many water bodies have been affected by the construction of dams and reservoirs for hydropower generation, flood protection, irrigation, water supply, and recreation. Globally, there are over 56 000 [...]

We analyzed changes in the condition, early growth, and resource use of lake trout (Salvelinus namaycush) from a Boreal Shield lake in response to an experimental aquaculture operation. Annual small-scale commercial production of rainbow trout (Oncorhynchus mykiss) resulted in increased lake trout body condition during aquaculture operations, which was positively related to minnow catch per unit effort (CPUE). Incremental increases in growth led to larger lake trout following aquaculture. While the littoral energy assimilated by lake trout did not change linearly from 2002 to 2009, we observed a shift towards littoral energy use in the last year of aquaculture and for 2 years after the experiment, coincident with low densities of Mysis diluviana. Lake trout trophic position declined from 2002 to 2009, suggesting increased foraging on secondary versus tertiary consumers. Minnow and slimy sculpin (Cottus cognatus) CPUE increased by 5.2- and 5.5-fold, respectively, and Mysis diluviana densities decreased by 93%. Changes observed in the experimental lake were much greater than those observed in a nearby reference lake. Our results suggest that moderate nutrient enrichment from aquaculture may benefit lake trout in oligotrophic Boreal Shield lakes. Nous avons analyse les changements de l'embonpoint, de la croissance precoce et de l'utilisation de ressources des touladis (Salvelinus namaycush) d'un lac du Bouclier boreal en reaction a une exploitation aquacole experimentale. La production commerciale annuelle a petite echelle de truites arc-en-ciel (Oncorhynchus mykiss) s'est traduite par une augmentation de l'embonpoint des touladis durant les activites d'aquaculture, qui etait positivement reliee a la captures par unite d'effort (CPUE) de menes. Des augmentations graduelles de la croissance se sont traduites par des touladis plus gros apres les activites aquacoles. Si l'energie littorale assimilee par les touladis n'a pas change lineairement de 2002 a 2009, nous avons observe un changement vers l'utilisation d'energie littorale durant la derniere annee d'aquaculture et pour 2 ans suivant l'experience, qui coincide avec de faibles densites de Mysis diluviana. La position trophique des touladis a baisse de 2002 a 2009, ce qui indiquerait une augmentation des consommateurs secondaires par rapport aux consommateurs tertiaires dans leur alimentation. Les CPUE de menes et de chabots visqueux (Cottus cognatus) ont ete multipliees par 5,2 et 5,5, respectivement, et les densites de Mysis diluviana ont connu une baisse de 93 %. Les changements observes dans le lac experimental etaient beaucoup plus importants que ceux observes dans un lac de reference situe a proximite. Nos resultats portent a croire qu'un enrichissement modere en nutriments provenant de l'aquaculture peut etre benefique pour les touladis dans des lacs oligotrophes du Bouclier boreal. [Traduit par la Redaction], Introduction Aquaculture has expanded rapidly and is the world's fastest growing food-production technology (Anderson et al. 2017). Freshwater caged aquaculture is expected to be a growing contributor to fish production; [...]

Cyanobacterial blooms in aquatic environments have impacted ecosystem health, altered food webs and contributed to substantial regional economic losses. The relative impacts of climate change, eutrophication and other environmental stressors on the formation of cyanobacterial blooms remain unclear as a consequence of the lack of long‐term data. The analysis of lake sediment archives can help address such questions.The abundance of target cyanobacterial genes was quantified using droplet digital PCR from two experimental and two reference lakes at the IISD ‐ Experimental Lakes Area, Northwestern Ontario, Canada where various anthropogenic drivers have been manipulated and phytoplankton biomass and taxonomy (via microscopy) tracked over the past 50 years.Based on sediment DNA (sedDNA) records, Lake 227 has seen more than two full orders of magnitude rise in cyanobacterial abundance in response to experimental nutrient (nitrogen and phosphorus) loading since 1969. Lake 223 also experienced a small increase in cyanobacterial abundance during a period of experimental acidification. The sedDNA archives also identified an increase in abundance of mcyE, a gene involved in microcystin synthesis, in Lake 227 after 1990 when experimental nitrogen loading ceased and only phosphorus loading continued. Sequencing of the cyanobacterial 16S rRNA gene from sedDNA revealed a shift towards Nostocales dominance in response to eutrophication in Lake 227; this was also seen in the more recent sediments of the other lakes but to a much lesser extent.When comparing the sedDNA data with historical phytoplankton records of the past ~50 years, moderate‐to‐strong correlations were found between the two. This research validated the use of sedDNA for the analysis of long‐term trends in lakes and the results revealed additional changes that were not recorded from the surface‐water records.Experimental nutrient loading had the greatest influence on the cyanobacterial community in Lake 227. However, climate change, via declines in heating degree days, was also significant in explaining variation in the cyanobacterial communities in the experimental lakes as well as the reference lakes. [ABSTRACT FROM AUTHOR]

The Dynafed data federator is designed to present a dynamic and unified view of a distributed file repository. We describe our use of Dynafed to construct a production-ready WLCG storage element (SE) using existing grid storage endpoints as well as object storage. Dynafed is used as the primary SE for the Canadian distributed computing cloud systems for the Belle-II experiment, where we use it in production for reading input files. We have run up to 6,000 Belle-II jobs simultaneously on distributed cloud resources, requiring the transfer of approximately 60 TB of input data per day. Similarly, we have been using a Dynafed-based SE in pre-production testing for the ATLAS experiment. We will describe the configuration of Dynafed to make it suitable as a WLCG SE. In particular, we will highlight the improvements within Dynafed that make it possible to do checksum based file verification and 3rd-party file copy via WebDAV. We will also report on a new monitoring system and an automated system that collects storage information from all endpoints.

We describe a high-throughput computing system for running jobs on public and private computing clouds using the HTCondor job scheduler and the cloudscheduler VM provisioning service. The distributed cloud computing system is designed to simultaneously use dedicated and opportunistic cloud resources at local and remote locations. It has been used for large scale production particle physics workloads for many years using thousands of cores on three continents. Cloudscheduler has been modernized to take advantage of new software designs, improved operating system capabilities and support packages. The result is a more resilient and scalable system, with expanded capabilities.