Daily cycle of zooplankton abundance in Magdalena Bay, B.C.S. Mexico

Abstract

This paper presents the daily variation of the abundance of zooplankton in Magdalena Bay, Mexico from sampling in a fixed-station for 10 days of February 2002. From 112 taxa identified barnacles nauplii and cladocerans Penilia avirostris and Pseudevadne tergestina were the most common and abundant with daily variation levels more than 100%. The copepods constituted one fifth of zooplankton abundance and 7 of the 80 species found were recorded for the first time in the study area. Zooplankton abundance showed partially coherent pattern with the hidrography of the bay as well as particles retention model. The 3 species of copepods more abundant were more numerous at the beginning of the time series but tended to reduce its density toward the end of the time of study. Winter hydrodynamics was identified as a factor of zooplankton concentration, perhaps more important than the temperature or the concentration of chlorophyll a, with a weight still not estimated in the structure of the community or the intensity of the interspecific relationships.