Loss Rates of Suspended Material Sedimented in a Marine Bay

Abstract

Loss rates for particulate carbon, nitrogen, chlorophyll a, and phaeophytin during the year in a coastal marine bay were calculated by comparison of sedimentation rates and suspended concentration of particulate matter available for deposition. Daily loss of carbon and nitrogen at various depths (1–6% with maximum values during late summer and autumn) generally decreased with depth and was highest when fecal pellet deposition increased during late summer. Loss rates of plant pigments were an order of magnitude lower than those of carbon and nitrogen, except when algal cells settled directly during winter. The observations substantiate previous assumptions that on a daily basis only a small proportion of suspended material is sedimented. Loss rate is dependent on the nature of the suspended particulate matter and physical structure of the water column. Key words: sedimentation, suspended particulate matter, settling velocity, coastal embayment