Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4253
Title: Surface distribution of brachyuran megalopae and ichthyoplankton in the Columbia River plume during transition from downwelling to upwelling conditions
Author: G. Curtis Roegner, Elizabeth A. Daly, Richard D. Brodeur
Publication Year: 2013
Journal: Continental Shelf Research
Keywords: Columbia River plume, crab megalopae, juvenile fishes, neuston, upwelling, California Current,Columbia River plume,crab megalopae,juvenile fishes,

The spring transition between downwelling and upwelling conditions along with the fluctuating structure of the Columbia River plume creates highly dynamic interactions with the California Current coastal boundary zone that affects regional geochemical processing and biological responses. In this study we measured biophysical properties of surface water during transition from downwelling to persistent seasonal upwelling conditions in 2010, when the spring transition was delayed and Columbia River flow was substantially higher than average. Plume waters that were initially trapped in a northward flowing coastal boundary current during downwelling conditions were advected offshore after several days of upwelling favorable winds. Neustonic samples of brachyuran larvae and ichthyoplankton exhibited varied response to the large seaward advective event. Megalopae of cancrid crabs exhibited patterns of both offshore transport (Cancer spp.) as well as nearshore retention (Cancer magister). Additionally, abundant numbers of large juvenile widow and yellowtail rockfish were sampled at a size appropriate for settlement and during ocean conditions that favor high recruitment success. These results demonstrate the response of planktonic crab larvae and ichthyoplankton to large scale advection varied by species, with larger and more vagile fish exhibiting less evidence of passive transport than smaller crab larvae. Importantly, portions of the planktonic fish and crab community were able to maintain nearshore distributions in favorable settlement habitat despite large physical forcing.

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Theme: Ecosystem Approach to Management for the California Current Large Marine Ecosystem
Foci: Characterize linkages between climatic conditions and biotic responses.