Vertical distribution of chlorophyll and phaeo-pigments : Baja California

Abstract

The vertical distribution of chlorophyll and phaeo-pigments were studied off Baja California. Concentrations of both increased with depth until a maximum was reached below which lower levels were observed. The chlorophyll maximum was usually near the base of the euphotic zone, in the thermocline. The phaeo-pigment maximum either coincided with the chlorophyll maximum or was at a slightly greater depth. The phaeo-pigment maximum coincided with that portion of the water column where nutrients increased in concentration. This layer possibly represents an accumulation of detritus, and an area where remineralization and lower re-utilization of nutrients occur. Phaeo-pigments are readily produced by zooplankters grazing on phytoplankton. A relationship exists between the number of zooplankters in the water column and the quantity of phaeo-pigments in the euphotic zone. Phaeo-pigments in the euphotic zone may be indicative of the past history of grazing activity in the water column, and may also be a measure of nutrient turnover.