Processes affecting the pigment content, spectral absorption, and photochemical properties of biogenic detritus derived from phytoplankton will be investigated. It is hypothesized that the rates of photooxidation of detrital chlorophylls, pheopigments, and carotenoids are coupled through a degradation, and the question of mechanism will be addressed in laboratory experiments, some employing a model system for detrital pigments. The effect of grazer community composition on the spectral character of biogenic detritus will be examined. Pigment content, spectral absorption, and the rates of light-dependent pigment bleaching will be determined for the particulate wastes of copepods and heterothrophic protozoans. Pigments will be analyed by high performance liquid chromatography. Particulate absorption spectra (filtered material) will be partitioned into component spectra by solvent extraction. The potential absorption of a relatively light-stable detrital fraction, of humic-like spectral character, will be assessed. The microscopic plants that are responsible for most of the ocean's biological production contain pigments for absorbing sunlight just as their terrestrial counterparts do. These pigments have long been used to quantify marine phytoplankton through direct chemical analysis of the amount of chlorophyll present in a given body of water. Recently, the discovery that phytoplankton distributions can be measured remotely based on the color they impart to the water has opened up exciting opportunities for the large scale analysis of marine production. Nelson's work on the pigment differences associated with various marine grazing environments may result in the ability to extract much more ecological information from remotely collected optical data than just the static differences in plant biomass. The approach of examining the mechanisms of pigment degration may allow for the actual analysis of biological dynamics such as marine food web dynamics and particle flux.
