Abundance, composition, and sinking rates of fish fecal pellets in the santa barbara channel

Abstract

Rapidly sinking fecal pellets are an important component of the vertical flux of particulate organic matter (POM) from the surface to the ocean's interior; however, few studies have examined the role fish play in this export. We determined abundance, size, prey composition, particulate organic carbon/nitrogen (POC/PON), and sinking rates of fecal pellets produced by a forage fish, likely the northern anchovy, in the Santa Barbara Channel. Pellet abundance ranged from 0.1-5.9 pellets m -3. POC and PON contents averaged 21.7 μg C pellet -1 and 2.7 μg N pellet -1. The sinking rate averaged 787 m d -1; thus pellets produced at the surface would reach the benthos (∼500 m) in <1 day. Estimated downward flux of fish fecal POC reached a maximum of 251 mg C m -2 d -1. This is equal to or exceeds previous measurements of sediment trap POM flux, and thus may transport significant amounts of repackaged surface material to depth.