The effects of the 1997–99 El Niño/La Niña events on hydrography and zooplankton off the central Oregon coast

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

“…Most species previously reported in Oregon waters during El Niño events (Peterson et al 2002 are commonly found both to the south and offshore of Oregon, making it difficult to differentiate whether their occurrence during El Niño events result from onshore versus northward advection. Collections of zooplankton reported on here illustrate that both onshore and poleward advection are biologically important transport mechanisms during El Niño: Nyctiphanes simplex could only have been transported into our study area by northward movement of water whereas the other euphausiids, the chaetognaths, and the copepod probably required some northward, but primarily onshore, transport to bring them to the Oregon coast.…”

“…Off central Oregon, USA, anomalously warm water was noted as early as May 1997 (Peterson et al 2002). The first definitive sign of the arrival of an oceanic El Niño signal was observed in late August, when the sea level rose by several centimeters (Strub & James 2002).…”

Chapter 1 Impacts of the Oceans on Climate Change

“…Large productivity crashes are also associated with ENSO events in the Pacific (e.g. Lavaniegos and Ohman, 2007;Peterson et al, 2002). These changes when seen together indicate that marine ecosystems are reacting beyond what might be expected from interannual variability.…”

Response of O<sub>2</sub> and pH to ENSO in the California Current System in a high-resolution global climate model

“…For instance, the influence of the strong 1997/1998 El Niño and subsequent La Niña on the coastal upwelling ecosystem of the US west coast has been well documented by a variety of observational studies that focus on the physics and hydrography (e.g., Collins et al, 2002;Kosro, 2002;Lynn and Bograd, 2002;Ryan and Noble, 2002;Schwing et al, 2002b), on nutrients and primary production (e.g., Castro et al, 2002;Mitchell, 2000, 2002;Kudela and Chavez, 2002), and on zooplankton and higher trophic levels (e.g., Benson et al, 2002;Hopcroft et al, 2002;Pearcy, 2002;Peterson et al, 2002). A handful of observational studies have investigated the impact of the 1982/1983 El Niño on the physical regime of the CalCS (e.g., Simpson, 1983;Huyer and Smith, 1985) and the effect of the 2002/2003 El Niño on the physics and biology (e.g., Murphree et al, 2003;Schwing et al, 2002a).…”