Distribution of particulate organic matter in Baja California, west coast of Mexico

Abstract

Spatial distribution of chl-a, proteins and carbohydrates from nano and microparticles was studied during R V El Puma cruise (10-15 October 1987). Thermally homogeneous surface layer (0-5 m, 25-26-degrees-C) was characterized by a significant relationship between nanophytoplanktonic chl-a, and nanoparticulate proteins and carbohydrates (r = 0.95 and 0.86, respectively), whereas in the thermal stratified layer (5-50 m, 25-16-degrees-C), these relationships were not significant. The same trends were obtained for the relationships between microphytoplankton chl-a, and microparticulate proteins and carbohydrates (r = 0.94 and 0.91, respectively at 5 m layer), despite their lower biomass (5 to 30% of nanophytoplankton biomass). Results suggested that protein and carbohydrate of nanophytoplankton were well represented in the surface homogeneous layer and accounted for 87 and 60% of the total nanoparticulate biomass respectively. However, in the thermally stratified layer, non-photosynthetic nano and microparticles dominated. This well-differentiated particle distribution corresponds to the presence of the Equatorial Surface Water, and to the California Current Water at the sub-surface layer.