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The pelagic ecosystem in the N orthern C alifornia C urrent off O regon during the 2014–2016 warm anomalies within the context of the past 20 years
A warm anomaly in the upper ocean, colloquially named “the Blob,” appeared in the Gulf of Alaska during the calm winter of 2013–2014, spread across the northern North Pacific (NP) Ocean, and shifted eastward and onto the Oregon shelf. At least 14 species of copepods occurred which had never been obs...
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Published in: | Journal of geophysical research. Oceans 2017-09, Vol.122 (9), p.7267-7290 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | A warm anomaly in the upper ocean, colloquially named “the Blob,” appeared in the Gulf of Alaska during the calm winter of 2013–2014, spread across the northern North Pacific (NP) Ocean, and shifted eastward and onto the Oregon shelf. At least 14 species of copepods occurred which had never been observed in shelf/slope waters off Oregon, some of which are known to have NP Gyre affinities, indicating that the source waters of the coastal “Blob” were likely of both offshore (from the west) and subtropical/tropical origin. The anomalously warm conditions were reduced during strong upwelling in spring 2015 but returned when upwelling weakened in July 2015 and transitioned to downwelling in fall 2015. The extended period of warm conditions resulted in prolonged effects on the ecosystem off central Oregon, lasting at least through 2016. Impacts to the lower trophic levels were unprecedented and include a novel plankton community composition resulting from increased copepod, diatom, and dinoflagellate species richness and increased abundance of dinoflagellates. Additionally, the multiyear warm anomalies were associated with reduced biomass of copepods and euphausiids, high abundance of larvaceans and doliolids (indictors of oligotrophic ocean conditions), and a toxic diatom bloom (
Pseudo‐nitzschia
) throughout the California Current in 2015, thereby changing the composition of the food web that is relied upon by many commercially and ecologically important species.
The unprecedented warm plankton community persisted for nearly three years altering the food chain for upper trophic levels
Persistent warm water events provide natural experiments that serve as proxies of potential future impacts on pelagic ecosystems
Long‐term ecological observation programs must be maintained so that ecosystem impacts of future change can be understood |
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ISSN: | 2169-9275 2169-9291 |
DOI: | 10.1002/2017JC012952 |