BIOCHEMICAL-COMPOSITION AND NUTRITIVE-VALUE OF SUSPENDED PARTICULATE MATTER OVER A TIDAL FLAT OF SOUTHERN CHILE

Seasonal fluctuations in the biochemical composition of the suspended particulate matter were followed during 2 years in a tidal flat of southern Chile. The suspended particulate matter load (seston) was highly dependent on tidal resuspension and primary productivity. Variations in carbohydrate, lipid and protein in the seston were primarily associated with the periods of high and low standing stocks observed in this environment. Their seasonal trends were very similar and highly correlated with those described for other components of the seston, such as organic matter, chlorophyll α and particulate organic carbon and nitrogen. The nutritional quality of the seston was expressed by a food index calculated on the base of the ratio of food material (lipid + carbohydrate + protein) to total seston. This index was negatively correlated with the inorganic fraction of the seston. Multiple regression analysis showed that the best model to explain the variation of the food index included the inorganic fraction of the seston and the particulate organic nitrogen, which together accounted for 85%. The results suggest that the gross analysis of the seston (organic and inorganic fractions) cannot describe fully its nutritive value and a detailed analysis of the biochemical composition is recommended to achieve a better understanding of the quality of the diet available to filter-feeders. © 1993 Academic Press. All rights reserved.