Vertical distribution of marine particles and grazers. I. Vertical distribution of food quality and quantity

Abstract

Vertical distributions of marine particle-grazers and their food were measured to examine whether the vertical distribution of food quality was distinct from that of food quantity. During an April cruise in the Southern California Bight there were no differences in the size spectra of food particles between the plant biomass maximum and the region of lower food quantity above it. The species assemblage of microplankton near the surface was more predictable than that at the microplankton biomass maximum, and was distinct from it. Species known to be noxious or distasteful to copepods were not members of either assemblage. The seston at both surface and depth contained unequal proportions of carbohydrate, protein, and lipid. Particulate nitrogen (and protein) per unit carbon was highest at the microplankton biomass maximum, particulate carbohydrate per unit carbon was highest near the surface.