Variabilidad anual del fitoplancton marino en áreas costeras de La Libertad y Manta (Ecuador), su inter-relación con eventos El Niño

Abstract

En este artículo se describen los resultados anuales de la biomasa fitoplanctónica cuantitativa (primer nivel trófico), períodos de mayor densidad fitoplanctónica anual en dos estaciones fijas de Manta (1991-1997), La Libertad (1994-1997) y su inter-relación en condiciones frías de 1996 y eventos cálidos El Niño en 1991-92 y 1997.

This paper describes the phytoplankton biomass composition and distribution (cell/l) in the surface and subsurrface levels, its seasonaly variability in two coastal station (ten miles offshore) in the south-eastern Pacific Ocean: Manta (1991 to 1997) with two event El Niño (1991-92; 1997); and La Libertad (1994 to 1997) with a event El Niño 1997. In this time its registered a could event during 1996 year. The highest concentration of phytoplankton >5x10 cell/l, its was present with the seasonal changes during winter to summer (april to may), and summer (june, july, august, september and october), its relationship with the termoclina position of 22-23°C. The less densities in this areas were present between the El Niño 1991-1992, to end 1995 and 1997 events. The phytoplankton was more representative neritic organisms to as Nitzschias, Chaetoceros, Rhizosolenias, Gymnodinium spp. and Oxytoxun spp., Messodinium rubrum, and microflagellates. In relationship of phytoplankton abundance during this study in Manta and La Libertad, registered different compositions: 1) Less phytoplankton biomass before El Niño 1991-1992; 2) Highest phytoplankton biomass before El Niño 1997.