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Ecosystems that are coupled by reciprocal flows of energy and nutrient subsidies can be viewed as a single "meta-ecosystem." Despite these connections, the reciprocal flow of subsidies is greatly asymmetrical and seasonally pulsed. Here, we synthesize existing literature on stream-riparian meta-ecosystems to quantify global patterns of the amount of subsidy consumption by organisms, known as "allochthony." These resource flows are important since they can comprise a large portion of consumer diets, but can be disrupted by human modification of streams and riparian zones. Despite asymmetrical subsidy flows, we found stream and riparian consumer allochthony to be equivalent. Although both fish and stream invertebrates rely on seasonally pulsed allochthonous resources, we find allochthony varies seasonally only for fish, being nearly three times greater during the summer and fall than during the winter and spring. We also find that consumer allochthony varies with feeding traits for aquatic invertebrates, fish, and terrestrial arthropods, but not for terrestrial vertebrates. Finally, we find that allochthony varies by climate for aquatic invertebrates, being nearly twice as great in arid climates than in tropical climates, but not for fish. These findings are critical to understanding the consequences of global change, as ecosystem connections are being increasingly disrupted.

As early-career professionals (ECPs) navigate their education and professional development in the aquatic sciences, many seek to build a network to help guide their entrance into the field. As influential organizations, scientific societies play a vital role through hosted conferences, where ECPs can meet and share ideas with others, and find mentors to facilitate their colleagues' journey within the profession. However, not all ECPs are the same, and those from marginalized backgrounds face unique challenges. Here, we provide a perspective on ways scientific societies can ensure all members are provided with equitable opportunity to discover, access, and build career-defining networks at conference events, including the critical role of mentors in navigating obstacles to success. Our recommendations originate from an early-career networking workshop in 2022 at a Canadian fisheries and aquatic sciences conference. The day-long hybrid event comprised interactive activities and discussions on how societies and their conferences can foster and promote inclusive networking for all, including suggestions on maximizing inclusivity for online attendees. This perspective serves as a call to action for scientific societies and senior-career professionals to meaningfully engage with ECPs and marginalized members to promote transformative science. [ABSTRACT FROM AUTHOR]

Smallmouth bass populations have expanded far beyond their native range and these predatory fish present a pervasive threat to native aquatic species throughout North America. In the western United States, smallmouth bass are now present in river and reservoir habitats where Pacific salmon are found and are considered a potential threat to salmon recovery in many locations. We conducted a study to determine if smallmouth bass are expanding their range in the mainstem Willamette River, Oregon, and developed a model to assess habitat overlap between smallmouth bass and juvenile Chinook salmon. Sampling during 2011–2022 revealed that the distribution of smallmouth bass had expanded throughout that timeframe to encompass the entire mainstem Willamette River, including important rearing habitats for juvenile Chinook salmon. The model predicted that smallmouth bass and juvenile Chinook salmon habitat overlap was substantial, highlighting the need for additional research to evaluate for potential negative impacts to salmon recovery in the basin. The model was also used to evaluate the efficacy of using flow management to reduce interactions between these two species, but the scenarios we examined suggested that this was not a viable option. These results highlight the need for continued research to assess interactions between smallmouth bass and juvenile salmon, and other native species of concern, in the Willamette River Basin. The development of the model is useful for resource managers to understand interactions between these species to prioritize locations for sampling in the future. [ABSTRACT FROM AUTHOR]

The importance of multiple processes and instream factors to aquatic biota has been explored extensively, but questions remain about how local spatiotemporal variability of aquatic biota is tied to environmental regimes and the geophysical template of streams. We used an individual-based trout model to explore the relative role of the geophysical template versus environmental regimes on biomass of trout (Oncorhynchus clarkii clarkii). We parameterized the model with observed data from each of the four headwater streams (their local geophysical template and environmental regime) and then ran 12 simulations where we replaced environmental regimes (stream temperature, flow, turbidity) of a given stream with values from each neighboring stream while keeping the geophysical template fixed. We also performed single-parameter sensitivity analyses on the model results from each of the four streams. Although our modeled findings show that trout biomass is most responsive to changes in the geophysical template of streams, they also reveal that biomass is restricted by available habitat during seasonal low flow, which is a product of both the stream's geophysical template and flow regime. Our modeled results suggest that differences in the geophysical template among streams render trout more or less sensitive to environmental change, emphasizing the importance of local fish-habitat relationships in streams. L'importance de nombreux processus et des facteurs a l'interieur de cours d'eau pour le biote aquatique a ete examinee en detail, mais des questions demeurent concernant le lien entre la variabilite spatiotemporelle du biote aquatique et les regimes de conditions ambiantes et le gabarit geophysique des cours d'eau. Nous avons utilise un modele de truite base sur l'individu pour explorer l'influence relative du gabarit geophysique et des regimes de conditions ambiantes sur la biomasse de truites (Oncorhynchus clarkii clarkii). Nous avons parametrise le modele a partir de donnees d'observation pour chacun des quatre cours d'eau d'amont (leur gabarit geophysique et leur regime ambiant), puis realise 12 simulations dans lesquelles nous avons remplace les regimes ambiants (temperature, debit, turbidite) d'un cours d'eau donnee par les valeurs de chacun des cours d'eau voisins, tout en maintenant le gabarit geophysique inchange. Nous avons egalement effectue des analyses de sensibilite des resultats du modele aux differents parametres pour chacun des quatre cours d'eau. Bien que les resultats du modele montrent que la biomasse de truites reagit le plus fortement a des modifications du gabarit geophysique des cours d'eau, ils revelent egalement que la biomasse est limitee par l'habitat disponible durant l'etiage saisonnier, qui est un produit du gabarit geophysique du cours d'eau et du regime d'ecoulement. Les resultats du modele donnent a penser que des differences sur le plan du gabarit geophysique entre les cours d'eau rendent les truites plus ou moins sensibles aux changements des conditions ambiantes, soulignant ainsi l'importance des relations locales poissons-habitats dans les cours d'eau. [Traduit par la Redaction], Introduction Our understanding that the land surrounding a stream rules the stream (Hynes 1975) is formative in stream ecology. These ideas evolved into a view of streams as a distribution [...]

Through their multiple functions, refuges may be important for stream‐living fishes, particularly during stressful events such as seasonal low flow or drought. Coastal Cutthroat Trout Oncorhynchus clarkii clarkii is an ideal study organism to understand the importance of refuge. During seasonal low flow, lower water levels limit access to refuge and emigration, survival of fish is low, and predation risk is high. Under these conditions, we studied patterns of cover use from field observations and tested predictions from multiple hypotheses about cover use in a semi‐natural experiment. Boulders were the main cover selected by trout in natural streams. Trout disproportionately used cover near deeper water, and they selected larger‐sized cover in shallower water. Trout showed plasticity to switch among behaviours, concealing under cover and emigrating as first options, followed by grouping, and then habitat shifting. Lack of feeding and growth suggested that perceived threat of predation was a more important driver of behaviour than foraging. Emigration was also linked to cover, with higher levels of emigration associated with less cover availability, revealing a potential link between refuge and demography through emigration. Except for feeding, the intensity of alternative behaviours can increase or decrease depending on refuge availability. Collectively, findings of this work indicate that cover can be considered a critical limiting resource along with other fundamental resources of food and space for stream‐living fish. [ABSTRACT FROM AUTHOR]