THE CARBON, NITROGEN AND MASS CONTENT OF MARINE SNOW AS A FUNCTION OFAGGREGATE SIZE

The particulate organic carbon (POC), particulate organic nitrogen (PO N), dry mass, and chlorophyll a content of marine snow as a function o f individual aggregate size was determined from undisturbed natural ag gregates photographed and collected in situ by SCUBA divers at 15 stat ions off coastal California in order to quantify the matter available in large particles for various ecological processes. POC, PON, and dry mass content were highly significant exponential functions of aggrega te volume and were similar for all aggregates regardless of aggregate type, origin, composition or season of collection. POC and PON made up 17-39% and 1.7-6.0%, respectively, of aggregates by weight. C:N ratio s increased with increasing aggregate size, suggesting that larger agg regates were older and more refractory than smaller ones. Similarity i n the size-specific POC, PON, and mass content of different types of a ggregates indicates that the quantities of these materials existing in the larger particle size fractions of the upper ocean could be estima ted from profiles of particle size and abundance with depth obtained w ith in situ camera systems. Such estimates will allow assessment of th e availability of marine snow to large particle consumers and decompos ers and to sedimentation processes. (C) 1998 Elsevier Science Ltd. All rights reserved.