Type of Presentation

Oral

Session Title

Changes in Ecosystem Function and Climate Revealed by Long-term Monitoring in the Salish Sea

Description

Hood Canal has a long history of seasonal hypoxia with fish kills reported more frequently in the recent decades. Because Euphausia pacifica is a dominant euphausiid species in Hood Canal and a key prey for fish, mammals, and seabirds, their responses to hypoxia and environmental changes play a key role in both ecosystem functioning and fisheries. Here, we investigate long-term variability in E. pacifica habitat availability using a combination of field observations and published data. Based on depth-stratified plankton tows at two stations in summer through fall, 2012 & 2013, we observed abundant juvenile and adult euphausiids in low dissolved oxygen waters in Hood Canal, e.g. O2/l, while their larvae showed clear avoidance of 2/l. Integrating field observations with published respiration experiments, we assess the proportion of habitats available for E. pacifica in each life stage under different temperature and oxygen they experienced in the field. Archive real-time vertical profiles of oceanographic data were obtained from the Oceanic Remote Chemical Analyzer (ORCA) buoys at multiple locations in Hood Canal. We compare temporal and spatial differences in the habitat availability during the last decade, including during “The Blob” when suitable habitats were substantially compressed for all life stages. We finally discuss the application of long-term data as a key tool to understand the challenges of future environmental change for euphausiids and, as a consequence, the food webs of temperate coastal ecosystems.

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The effect of interannual variation in oxygen concentration and temperature on euphausiid habitat availability in Hood Canal, WA, 2006-2015

2016SSEC

Hood Canal has a long history of seasonal hypoxia with fish kills reported more frequently in the recent decades. Because Euphausia pacifica is a dominant euphausiid species in Hood Canal and a key prey for fish, mammals, and seabirds, their responses to hypoxia and environmental changes play a key role in both ecosystem functioning and fisheries. Here, we investigate long-term variability in E. pacifica habitat availability using a combination of field observations and published data. Based on depth-stratified plankton tows at two stations in summer through fall, 2012 & 2013, we observed abundant juvenile and adult euphausiids in low dissolved oxygen waters in Hood Canal, e.g. O2/l, while their larvae showed clear avoidance of 2/l. Integrating field observations with published respiration experiments, we assess the proportion of habitats available for E. pacifica in each life stage under different temperature and oxygen they experienced in the field. Archive real-time vertical profiles of oceanographic data were obtained from the Oceanic Remote Chemical Analyzer (ORCA) buoys at multiple locations in Hood Canal. We compare temporal and spatial differences in the habitat availability during the last decade, including during “The Blob” when suitable habitats were substantially compressed for all life stages. We finally discuss the application of long-term data as a key tool to understand the challenges of future environmental change for euphausiids and, as a consequence, the food webs of temperate coastal ecosystems.