Closing the gap between science and management of cold-water refuges in rivers and streams

Human activities and climate change threaten coldwater organisms in freshwater eco-systems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive management approaches are needed that consider interlinked physical, biological, and social factors of cold-water refuges. We review current understanding of cold-water refuges, identify gaps between science and management, and evaluate policies aimed at protecting thermally sensitive species. Existing policies include designating cold-water habitats, restricting fishing during warm periods, and implementing threshold temperature standards or guidelines. However, these policies are rare and uncoordinated across spatial scales and often do not consider input from Indigenous peoples. We propose that cold-water refuges be managed as dis-tinct operational landscape units, which provide a social and ecological context that is relevant at the watershed scale. These operational landscape units provide the founda-tion for an integrated framework that links science and management by (1) mapping and characterizing cold-water refuges to prioritize management and conservation actions, (2) leveraging existing and new policies, (3) improving coordination across jurisdictions, and (4) implementing adaptive management practices across scales. Our findings show that while there are many opportunities for scientific advancement, the current state of the sciences is sufficient to inform policy and management. Our proposed framework pro-vides a path forward for managing and protecting cold-water refuges using existing and new policies to protect coldwater organisms in the face of global change. behavioral thermoregulation, climate change adaptation, lotic ecosystem management, refugia, salmonids, temperature, thermal heterogeneity, thermal refugespublishedVersio

Primitive layered gabbros from fast-spreading lower oceanic crust

Three-quarters of the oceanic crust formed at fast-spreading ridges is composed of plutonic rocks whose mineral assemblages, textures and compositions record the history of melt transport and crystallization between the mantle and the sea floor. Despite the importance of these rocks, sampling them in situ is extremely challenging owing to the overlying dykes and lavas. This means that models for understanding the formation of the lower crust are based largely on geophysical studies and ancient analogues (ophiolites) that did not form at typical mid-ocean ridges. Here we describe cored intervals of primitive, modally layered gabbroic rocks from the lower plutonic crust formed at a fast-spreading ridge, sampled by the Integrated Ocean Drilling Program at the Hess Deep rift. Centimetre-scale, modally layered rocks, some of which have a strong layering-parallel foliation, confirm a long-held belief that such rocks are a key constituent of the lower oceanic crust formed at fast-spreading ridges. Geochemical analysis of these primitive lower plutonic rocks-in combination with previous geochemical data for shallow-level plutonic rocks, sheeted dykes and lavas-provides the most completely constrained estimate of the bulk composition of fast-spreading oceanic crust so far. Simple crystallization models using this bulk crustal composition as the parental melt accurately predict the bulk composition of both the lavas and the plutonic rocks. However, the recovered plutonic rocks show early crystallization of orthopyroxene, which is not predicted by current models of melt extraction from the mantle and mid-ocean-ridge basalt differentiation. The simplest explanation of this observation is that compositionally diverse melts are extracted from the mantle and partly crystallize before mixing to produce the more homogeneous magmas that erupt

Closing the gap between science and management of cold‐water refuges in rivers and streams

Human activities and climate change threaten coldwater organisms in freshwater ecosystems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive management approaches are needed that consider interlinked physical, biological, and social factors of cold-water refuges. We review current understanding of cold-water refuges, identify gaps between science and management, and evaluate policies aimed at protecting thermally sensitive species. Existing policies include designating cold-water habitats, restricting fishing during warm periods, and implementing threshold temperature standards or guidelines. However, these policies are rare and uncoordinated across spatial scales and often do not consider input from Indigenous peoples. We propose that cold-water refuges be managed as distinct operational landscape units, which provide a social and ecological context that is relevant at the watershed scale. These operational landscape units provide the foundation for an integrated framework that links science and management by (1) mapping and characterizing cold-water refuges to prioritize management and conservation actions, (2) leveraging existing and new policies, (3) improving coordination across jurisdictions, and (4) implementing adaptive management practices across scales. Our findings show that while there are many opportunities for scientific advancement, the current state of the sciences is sufficient to inform policy and management. Our proposed framework provides a path forward for managing and protecting cold-water refuges using existing and new policies to protect coldwater organisms in the face of global change

Nature and Origin of the Oceanic Lithosphere: Some Insights from Past Ocean Drilling and Plans for the Future

The Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) have fundamentally changed our understanding of the Earth system. Drilling in the south Atlantic Ocean provided the critical test of the theory of plate tectonics and initiated innovative programs to investigate the products, fluxes, and processes associated with the creation, evolution, and recycling of the oceanic lithosphere. Key findings include a new and evolving understanding of the range and complexity of processes of oceanic lithosphere creation, and their probable importance in global geochemical cycles and seawater composition over time. Major questions remain about details, rates, and significance of lithospheric processes and fluxes. The expanded capabilities of the Integrated Ocean Drilling Program (IODP, to begin in 2003), will offer many exciting opportunities, including a chance to assess the role of lithospheric creation in global geochemical and climatic cycles. Résumé Le Deep Sea Drilling Project (DSDP) [projet de forages des fonds océaniques profonds] et le Ocean Drilling Program (ODP) [programme de forages océaniques] ont changé fondamentalement notre compréhension du système terrestre. Le forage de l'océan Atlantique sud a constitué le test déterminant de la théorie de la tectonique des plaques, et a permis de lancer des programmes d'étude inédits des produits, flux et processus liés à la création, l'évolution et le recyclage de la lithosphère océanique. Parmi les retombées de première importance se trouve cette compréhension nouvelle et en pleine évolution quant à l'étendue et la complexité des processus de création lithosphérique océanique et leur importance probable sur les cycles géochimiques planétaires et la composition de l'eau de mer dans le temps. D'importantes questions demeurent sans réponse quant aux détails, aux taux et à la portée des processus et flux lithosphériques. Les capacités accrus du Integrated Ocean Drilling Proram (IODP) [programme intégré de forages des fonds océaniques] devant débuter en 2003 offrira de nombreuses perspectives stimulantes, dont une occasion d'évaluer le rôle de la création lîthosphérique sur les cycles géochimiques et climatiques planétaires