Coastal Upwelling Supplies Oxygen-Depleted Water to the Columbia River Estuary

Low dissolved oxygen (DO) is a common feature of many estuarine and shallow-water environments, and is often attributed to anthropogenic nutrient enrichment from terrestrial-fluvial pathways. However, recent events in the U.S. Pacific Northwest have highlighted that wind-forced upwelling can cause naturally occurring low DO water to move onto the continental shelf, leading to mortalities of benthic fish and invertebrates. Coastal estuaries in the Pacific Northwest are strongly linked to ocean forcings, and here we report observations on the spatial and temporal patterns of oxygen concentration in the Columbia River estuary. Hydrographic measurements were made from transect (spatial survey) or anchor station (temporal survey) deployments over a variety of wind stresses and tidal states during the upwelling seasons of 2006 through 2008. During this period, biologically stressful levels of dissolved oxygen were observed to enter the Columbia River estuary from oceanic sources, with minimum values close to the hypoxic threshold of 2.0 mg L−1. Riverine water was consistently normoxic. Upwelling wind stress controlled the timing and magnitude of low DO events, while tidal-modulated estuarine circulation patterns influenced the spatial extent and duration of exposure to low DO water. Strong upwelling during neap tides produced the largest impact on the estuary. The observed oxygen concentrations likely had deleterious behavioral and physiological consequences for migrating juvenile salmon and benthic crabs. Based on a wind-forced supply mechanism, low DO events are probably common to the Columbia River and other regional estuaries and if conditions on the shelf deteriorate further, as observations and models predict, Pacific Northwest estuarine habitats could experience a decrease in environmental quality

The proportion of remineralized nitrate on the ice-covered eastern Bering Sea shelf evidenced from the oxygen isotope ratio of nitrate

We present measurements of nitrate and its natural abundance oxygen isotope composition (18O/16O) in the water column of the broad and shallow eastern Bering Sea shelf in the late winter and early spring of 2007 and 2008. In both years, nitrate concentrations showed a characteristic decrease, from 25 µM at the slope to ≤5 µM inshore. The 18O/16O ratio of nitrate (δ18ONO3 versus SMOW) also decreased from 3.2‰ at the slope to 1.5‰ inshore in 2007 and to as low as −1‰ inshore in 2008, indicating that nitrate inshore was nitrified at least once since having been entrained as nitrate from the slope. The shoreward decrease was less pronounced in 2007 due to 18O enrichment of nitrate from incident phytoplankton assimilation in the ice‐covered water column, whereas little to no algal growth in the water column was evident in 2008. By comparing the δ18O of nitrate to that of ambient water in spring 2008, we estimate the fraction of nitrate that was remineralized in situ rather than recently advected from the slope. These estimates indicate that 20%–100% of the nitrate in winter water of the middle and inner shelves derives from regeneration directly on the shelf rather than from the seasonal entrainment of slope waters, with recycling being the dominant mode of seasonal nitrate recharge from the 70 m isobath shoreward. These observations indicate substantial nutrient recycling on the shallow shelf, which has direct implications for the extent of fixed N loss to benthic denitrification and the fertility of the eastern shelf

Beyond Community Engagement: Transforming dialogues in art, education and the cultural sphere

This book reconsiders fundamental questions about relationships between community engagement, art and education within cultural spheres. Transdisciplinary chapters bring together researchers as “insider-practitioners” to challenge assumptions and offer new insights about practice, engagement and possibilities for transformation. The chapters reflect both localised projects and international perspectives on ecologies of practice as a key marker of the mobility of ideas as well as social mobility. Addressing socially engaged, informal pedagogy re-examines the aesthetic possibilities of social capital in the public domain. Re-considering contributions of education and research through transfer of knowledge and expertise across small social collectives, partnerships and larger institutional agencies is a growing practice. Examining equity and types of participation alongside issues of local and global significance is emergent in new, pop-up and continuing communities. Gauging social impact through case studies is an important project within the tertiary sector to ensure that critically reflexive visual research methodologies gain currency within contemporary neo-liberal funding and educational agendas. In the current milieux we ask, is all engagement transformative, educative, sustainable and linked to democratizing principles that address civic agendas? Re-imagining sites/situations of learning, culture and place as “practice encounters” utilises practices relevant for educators and practitioners. Applications of ecology, practice architectures and site ontologies inform broader social challenges. Conceiving arts-based research as a network, prioritises transitions and becomings to re-conceptualise the significance of relationships within local/global connectivity. Linking professional networks and agencies to adaptive communities, creates an expanded field of real world creative partnerships to enable changing pedagogies