Biological Consequences of the 1982–83 EI Niño in the Eastern Pacific

Abstract

The drastic changes in the abiotic environment caused by El Niño (EN) 1982–83 led to marked repercussions in the fauna and flora of the marine ecosystem, including pelagic and benthic marine subsystems and the seashore. Some of them were of a negative, others were of a positive nature. Mass mortalities of some species contrasted with enormous proliferations of others. Many species emigrated during EN from their traditional, cool upwelling areas, which had been converted to tropical or unusually warm conditions. Some moved towards deeper water, others poleward where conditions resembled those in their former habitat. Growth, body condition, reproduction and adult survival of some species were diminished. Also, changes in growth and survival of early life history stages affected recruitment of some species years later. At the same time dispersal stages of warm water species were transported south-/northward, and juveniles and adults actively invaded unusual areas. The biological effects of EN 1982–83 have been summarized in various conference volumes (Arntz et al. 1985b; CONCYTEC 1985; IFOP 1985; Robinson and del Pino 1985; Wooster and Fluharty 1985; IOC 1986; AGU 1987) and a number of reviews (Barber and Chávez 1983, 1986; Arntz 1984, 1986; McGowan 1984; Barber et al. 1985; Mysak 1986; Pearcy and Schoener 1987; Alvial 1988; Arntz and Fahrbach 1991).