MEPS 295:43-48 (2005)  -  doi:10.3354/meps295043

Biological indicators of the timing and direction of warm-water advection during the 1997/1998 El Niño off the central Oregon coast, USA

Julie E. Keister1,*, Travis B. Johnson2, Cheryl A. Morgan3, William T. Peterson4

1Oregon State University, College of Oceanic and Atmospheric Sciences, 104 COAS Administration Building, Corvallis, Oregon 97331-5503, USA
2Ocean Research Institute, The University of Tokyo, Center for International Cooperation, 1–51–1 Minamidai, Nakano-ku, Tokyo 164–8639, Japan
3Oregon State University, Cooperative Institute for Marine Resources Studies, 2030 S. Marine Science Drive, Newport, Oregon 97365, USA
4NOAA Fisheries, Hatfield Marine Science Center, 2030 S. Marine Science Drive, Newport, Oregon 97365, USA

ABSTRACT: Unusual collections of several euphausiid, chaetognath, and copepod species help elucidate the effects of the strong 1997/1998 El Niño off the central Oregon, USA, coast. Furcilia of Nyctiphanes simplex, a euphausiid typically found only as far north as central California, were collected in bi-weekly nearshore samples between December 1997 and November 1998. N. simplex was reported in summer 1998 as far north as the northern tip of Vancouver Island, British Columbia, Canada (51°N); our bi-weekly collections off Oregon allow us to use that species to help resolve the timing of arrival and disappearance of the biological signal of the El Niño, which was delayed by several months beyond the physical signal. Additionally, 2 species of euphausiid (Euphausia recurva and E. mutica), 2 species of chaetognath (Sagitta pseudoserratodentata and S. hexaptera), and 1 copepod (Centropages bradyi) that have never before been reported in coastal Oregon waters were collected in samples taken between 28 and 103 km off Oregon during the 1997/1998 El Niño. The 1997/1998 El Niño was one of the strongest on record and the occurrence of the unusual species may indicate the extent of the northward and onshore advection of warm water into the study area.

KEY WORDS: Nyctiphanes simplex · El Niño · Euphausids · Sagitta spp. · Range extension · Advection · Oregon · Zooplankton

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