Ontogcnetic vertical migration in Sebastolobus altivelis as a mechanism for transport of particulate organic matter at continental slope depths

Abstract

Ontogenetic vertical migration by a demersal fish inhabiting the continental slope off central California was studied as a mechanism for coupling transport of particulate matter between surface waters and the bathyal sea floor. We conducted a 1‐yr survey of Sebastolobus altivelis, a dominant demersal fish, over much of its depth range (400–1,600 m), with a camera sled and bottom trawl. This scorpaenid spawns gelatinous masses of eggs which float to the surface. After hatching, S. altivelis has a protracted pelagic phase and settles as a benthic juvenile at a length of ∼55 mm. We determined the production of particulate organic matter (POM) in masses of eggs as a measure of the passive upward flux of POM, and the recruitment of POM by settling juveniles as a measure of active transport back to the sea floor. Upward and downward fluxes of particulate organic carbon (POC) associated with planktonic development and ontogenetic migration of S. altivelis were 4.1–5.8 and 3.0–5.5 mg C m−2 yr−1. These upward and downward fluxes are lower by factors of ∼10 and ∼104 than the reported passive upward and downward fluxes measured with particulate interceptor traps in the eastern North Pacific. These data suggest that at bathyal depths, it is unlikely that vertical ontogenetic migrations contribute >1% to the POC flux reaching the deep‐sea floor. The upward flux of POC as buoyant eggs could represent, however, a significant portion of the total upward flux.