Search

Small lakes ( Key words: lake, forestry, riparian, water quality, plankton, fish, Introduction There has been increased interest in recent decades regarding the connectivity within the freshwater landscape (e.g., Jones et al. 2019), with a growing recognition of stream, wetland (e.g., Fritz [...]

Lake deltas (LDs) receive nutrient and energy subsidies from upstream habitats. These inputs can support LD benthic production. However, LDs may also receive impacts from upstream disturbance. Small lakes in coastal British Columbia often have inflow streams from areas with forest harvesting, which is pervasive in this region. Forest harvesting impacts can alter stream production, although downstream impacts on lakes, compared to streams, are less studied and understood. We aimed to test whether benthic LD communities (biofilm and invertebrates) are more productive and (or) diverse compared to other communities along the lakeshore (LS) (non-LDs), and whether there are differences in LD communities associated with upstream harvesting. We compared LD communities with upstream riparian areas that were harvested (HLD) or relatively undisturbed (ULD), and LS sites. We found that while community structure was similar across sites, ULDs had higher biofilm and invertebrate standing stocks (1.5- and 2-times higher, respectively) than HLDs and LS sites. Our results suggest subsidies and benthic production were higher at ULDs. These results advance our understanding of forest harvesting disturbance and stream-lake connectivity. Key words: Stream, lake delta, lake, forestry, biofilm, invertebrates, Introduction Streams and lakes are interconnected throughout the riverscape (e.g., Jones 2010; Covino 2017); however, empirical research on stream connections to lakes has been somewhat limited (e.g., review in Jones [...]

Western red cedar (Thuja plicata Donn ex D.Don) is a dominant species in forests of the Pacific Northwest in North America, but little is known about its decomposition in riparian habitat. We experimentally tested how early-stage mass loss of cedar leaf litter varied with distance from the stream (five distances from 1 to 40 m away) and responded to nutrient and water additions near four headwater streams in southwestern British Columbia. We ran three coarse-mesh litterbag trials in durations between five months to one year from January 2013 and January 2014. Litterbags were either untreated or given the following treatments: water additions during dry summer months, nitrogen and phosphorus additions, or additions of both. Control litterbags lost 21% initial mass over 12 months (January 2013-January 2014), 20% over five months (January 2013-June 2013), and 15% over eight months (June 2013-January 2014). Rates of mass loss did not increase with water in any trial but did increase with nutrients in the 12-month trial. Litter located 40 m from the stream lost 7% more mass than that located 1 m away in this same trial. Our study indicates that cedar leaf litter mass loss responded primarily to nutrient additions. Key words: Thuja plicata, coniferous, decomposition, nitrogen, phosphorus. Le thuya geant (Thuja plicata Donn ex D.Don) est une espece dominante dans les forets du Pacific Northwest en Amerique du Nord, mais on connait peu de choses au sujet de sa decomposition dans les habitats riverains. Nous avons teste experimentalement la facon dont la perte de masse initiale de la litiere de feuilles du thuya geant varie en fonction de la distance d'un cours d'eau (cinq distances de 1 a 40 m) et reagi a l'apport de nutriments et d'eau pres de quatre cours d'eau de tete dans le sud-ouest de la Colombie-Britannique. Nous avons realise trois essais avec des sacs de litiere a maille large d'une duree de cinq mois a un an, de janvier 2013 a janvier 2014. Les sacs de litiere ont ete, soit non traites, soit traites comme suit: apports d'eau durant les mois secs d'ete, apports d'azote et de phosphore, ou apports d'eau et de nutriments. Les sacs de litiere temoins ont perdu 21% de leur masse initiale apres 12 mois (janvier 2013 a janvier 2014), 20% apres cinq mois (janvier a juin 2013), et 15% apres huit mois (juin 2013 a janvier 2014). Le taux de perte de masse n'a pas augmente avec l'apport d'eau dans aucun des essais mais il a augmente avec l'apport de nutriments dans l'essai d'une duree de 12 mois. La litiere situee a 40 m d'un cours d'eau a perdu 7% plus de masse que celle qui etait situee a un metre dans le meme essai. Notre etude indique que la perte de masse de la litiere de feuilles du thuya geant a surtout reagi a l'apport de nutriments. [Traduit par la Redaction] Mots-cles: Thuja plicata, coniferien, decomposition, azote, phosphore., Introduction Leaf litter decomposition is vital to biogeochemical cycles in forest ecosystems (Krishna and Mohan 2017). More than half of global annual production in forests enters detrital food webs (Gosz [...]

Tributary junctions are regarded as ecologically important due to unique habitat present; however, there is limited understanding of the drivers of habitat attributes at these locations. Using six sites across two mainstem rivers, we tested whether tributary size relative to main stem governs the strength and direction of response of substrate size, stream temperature, and nutrient and coarse particulate organic matter (CPOM) concentration. We found that only phosphorus and CPOM concentration showed a significant relationship with relative tributary size. Small tributaries contributed high concentrations, whereas concentrations in larger tributaries resembled the main stem. Often, tributary exports were enough to increase the resource concentration in the main stem by 40%. Substrate coarsened by ~60% downstream of tributaries. Temperature asynchrony was observed, where tributaries contributed water between 2.8[degrees]C cooler to 1.9[degrees]C warmer than the main stem within one diel period. Our results highlight the importance of small tributaries for whole network functioning. However, large spatiotemporal variability revealed how habitat attributes are highly context-dependent in these locations and may be difficult to predict in both scientific and management settings. Si les milieux de confluence d'affluents sont juges importants sur le plan ecologique en raison des habitats singuliers qu'ils recelent, la comprehension des facteurs qui influent sur les attributs d'habitats dans ces endroits est toutefois limitee. En utilisant six sites dans les cours principaux de deux rivieres, nous avons verifie si la taille de l'affluent par rapport a celle du bras principal regit la force et la direction des reactions en ce qui concerne la taille du materiau du substrat, la temperature dans le cours d'eau et les concentrations de nutriments et de particules organiques grossieres (POG). Nous constatons que seules les concentrations de phosphore et de POG presentent une relation significative avec la taille relative de l'affluent. Les petits affluents fournissent de fortes concentrations, alors que les concentrations dans les plus grands affluents sont semblables a celles du bras principal. Dans bien des cas, les exportations provenant d'affluents suffisent pour accroitre de 40 % la concentration de ressources dans le bras principal. La granulometrie du substrat augmente d'environ 60 % en aval d'affluents. Une asynchronie des temperatures est observee, les affluents fournissant de l'eau de 2,8[degrees]C plus froide a 1,9[degrees]C plus chaude que l'eau dans le bras principal sur une periode de 24 h. Nos resultats soulignent l'importance des petits affluents pour le fonctionnement du reseau dans son ensemble. Une grande variabilite spatiotemporelle revele toutefois une forte dependance des attributs de l'habitat sur le contexte dans ces lieux, qui peut compliquer la prediction de ces attributs dans le contexte tant de la recherche scientifique que de la gestion. [Traduit par la Redaction], Introduction Heterogeneity in food resources and the structural components of habitat influence the distribution of organisms, which are key agents of nutrient cycling, energy transfer, and provide many of the [...]

Objective: Opioid use disorder (OUD) affects approximately 5.6 million people in the United States annually, yet rates of the use of effective medication for OUD (MOUD) treatment are low. We conducted an observational cohort study from August 2017 through May 2021, the MOUD Study, to better understand treatment engagement and factors that may influence treatment experiences and outcomes. In this article, we describe the study design, data collected, and treatment outcomes. Methods: We recruited adult patients receiving OUD treatment at US outpatient facilities for the MOUD Study. We collected patient-level data at 5 time points (baseline to 18 months) via self-administered questionnaires and health record data. We collected facility-level data via questionnaires administered to facility directors at 2 time points. Across 16 states, 62 OUD treatment facilities participated, and 1974 patients enrolled in the study. We summarized descriptive data on the characteristics of patients and OUD treatment facilities and selected treatment outcomes. Results: Approximately half of the 62 facilities were private, nonprofit organizations; 62% focused primarily on substance use treatment; and 20% also offered mental health services. Most participants were receiving methadone (61%) or buprenorphine (32%) and were predominately non-Hispanic White (68%), aged 25-44 years (62%), and female (54%). Compared with patient-reported estimates at baseline, 18-month estimates suggested that rates of abstinence increased (55% to 77%), and rates of opioid-related overdoses (7% to 2%), emergency department visits (9% to 4%), and arrests (15% to 7%) decreased. Conclusions: Our results demonstrated the benefits of treatment retention not only on abstinence from opioid use but also on other quality-of-life metrics, with data collected during an extended period. The MOUD Study produced rich, multilevel data that can lay the foundation for an evidence base to inform OUD treatment and support improvement of care and patient outcomes. [ABSTRACT FROM AUTHOR]

Generally, governments and industry have implemented some degree of protection to reduce the impacts of forestry on aquatic ecosystems. Here, we consider the widespread application of streamside management in terms of riparian buffer retention to protect freshwaters from forestry practices across three jurisdictions with large and intensive forestry sectors (British Columbia, Finland and Sweden).This perspective was developed by working with researchers, practitioners and policymakers on mitigation measures to decrease the impacts of forestry on streams. We demonstrate that it is exceedingly rare for policies and guidelines to specify concrete objectives and measurable targets that can be assessed against riparian buffer management outcomes. Most often, policy objectives for riparian management prescribe 'to prevent or mitigate impacts', and this vagueness is insufficient to protect our waters. We argue that we should be clearer about the targets (outcomes) for riparian management and go beyond the simple idea that buffer presence, without further specification of its conditions, is always a successful protection strategy. One cannot measure the effectiveness of rules and guidelines without quantitative targets.Policy implications: In this paper, we suggest that locally developed and adjusted targets for riparian buffers must include quantifiable, measurable goals that specify what is supposed to be achieved and protected with respect to ecological functions, biological communities or other values. It should be relatively simple to move from current vague objectives such as 'protect and prevent' to a defined range of values for ecological parameters that buffers are supposed to provide. For example, these can include region‐specific shading levels and microclimate targets, large wood volumes, or riparian forest species composition. We stress that these targets must be developed through an open dialogue between agencies, practitioners, land owners and scientists. We acknowledge that there are trade‐offs between being too prescriptive and too vague. However, when excessively broad goals are the norm, we lose the capacity to effectively implement, monitor or evaluate the outcomes of protection measures. [ABSTRACT FROM AUTHOR]

The influence of stream channel structure on the production of prey for drift-feeding fish is not well understood. We quantified drift production, the entry rate per streambed area, and drift flux, the total export rate per channel unit, in three second-order, forested streams in southwest British Columbia, Canada. We tested whether (1) drift production was higher in riffles than in pools, (2) drift flux increased with riffle length, and (3) prey body size was larger from riffles relative to pools and from terrestrial drop relative to aquatic drift. Total and aquatic-derived drift production (mg x [m.sup.-2] x [h.sup.-1]) was ~3.5 times higher in riffles relative to pools; however, terrestrial drift did not differ between channel types. Total drift flux (mg x [h.sup.-1]) was positively related to riffle length. Terrestrial invertebrates were approximately three times larger than aquatics, and invertebrates from riffles were approximately three times larger on average than those from pools. These results suggest that channel structure directly affects prey availability and prey quality for drift-feeding fish and that long riffles may be key areas of prey generation. L'influence de la structure du chenal d'un cours d'eau sur la production de proies pour les poissons se nourrissant d'organismes a la derive n'est pas bien comprise. Nous avons quantifie la production d'organismes a la derive, le taux d'entree par unite de surface du lit du cours d'eau et le flux d'organismes a la derive, soit le taux d'exportation total par unite de chenal, dans des cours d'eau forestiers de deuxieme et troisieme ordres du sud- ouest de la Colombie-Britannique (Canada). Nous avons verifie si (1) la production d'organismes a la derive etait plus grande dans les seuils que dans les fosses, (2) le flux d'organismes a la derive augmentait parallelement a la longueur du seuil et (3) la taille du corps des proies etait plus grande dans les seuils que dans les fosses et pour les proies provenant du milieu terrestre que pour les proies aquatiques a la derive. La production d'organismes a la derive totale et provenant du milieu aquatique (mg x [m.sup.-2] x [h.sup.-1]) etait ~3,5 fois plus grande dans les seuils que dans les fosses; cependant, la derive d'origine terrestre ne variait pas selon le type de chenal. Le flux d'organismes a la derive total (mg x [h.sup.-1]) etait positivement relie a la longueur du seuil. Les invertebres terrestres etaient environs trois fois plus grands que les invertebres aquatiques, et les invertebres issus des seuils etaient environs trois fois plus grands en moyenne que ceux des fosses. Ces resultats donnent a penser que la structure du chenal a une incidence directe sur la disponibilite et la qualite des proies pour les poissons qui se nourrissent d'organismes a la derive et que les longs seuils pourraient etre d'importantes zones de generation de proies., Introduction Invertebrate drift, the downstream transport of suspended macroinvertebrates, is a primary source of prey for many stream fishes including salmon and trout (Salmonidae). Together, drift abundance and habitat conditions [...]