Variability of community structure of Copepoda related to El Nino 1982-83 and 1987-88 along the west coast of Baja California Peninsula, Mexico

Copepod community structure and abundance of the most abundant species were studied during 15 cruises made between 1982 and 1989 along the west coast of the Baja California Peninsula, Mexico. The number of species and species diversity (Shannon's index) for each sampling station of the oceanographic cruises mere obtained. Though the zone was dominated during the year by th e tropical copepod component, similarities between El Nino 1982-83 and 1987 -88 were observed. Tropical-equatorial populations were added to the regula r tropical composition (50%) of the community of copepods resulting in a wi de distribution of those populations in 1982-83 and in 1987-88. The scenari o in 1984-89 (without 1981-88) was significantly different from both El Nin os because of the sea surface temperature, the species diversity, and the t ropical copepod component, although 1982 was similar to 1985 in diversity i ndex and number of species. Environmental conditions prevailing along the w est coast of Baja California during El Nino indicate that in 1982-83 the ef fect on the copepod community was greater than during the 1987-88 event.