Relationship of mesozooplankton and nanophytoplankton with temperature and salinity in Great Islands zone, Gulf of California

Abstract

Relationship of mesozooplankton (measured as protein and carbohydrate), and nanophytoplankton (as chlorophyll a) with temperature and salinity, was studied during August-September 1987. Circulation in the upper Gulf followed its general dynamics despite the presence of an ENSO (El Nino Southern Oscillation) event. A tongue of relatively high salinity water flowed southward through the Ballenas Channel and mixed with a water mass of lower salinity from the central Gulf, creating a front which promoted a patch of nanophytoplankton and mesozooplankton. Surface chl a from nanophytoplankton increased from 0.2 to 1.1 mg.m-3 through 10 miles south of San Lorenzo Island. Protein and carbohydrate from mesozooplankton showed 2 sub-surface (20 m) patches, with 20-50 and 15-45 mg.m-3 respectively in the same area. Fronts can be regarded as places of biological significance due to the accumulation of living and non living organic material.