Depth attenuation of organic matter export associated with jelly falls

Mario Lebrato, Markus Pahlow, Andreas Oschlies, Kylie A. Pitt, Daniel O. B. Jones, Juan Carlos Molinero and Robert H. Condon

Limnol. Oceanogr., 56(5), 2011, 1917-1928 | DOI: 10.4319/lo.2011.56.5.1917

ABSTRACT: We explore the attenuation in the export ratio of jelly-POM (particulate organic matter) with depth as a function of the decay rate, temperature, and sedimentation rate. Using data from the Vertical Transport In the Global Ocean project, we compare ratios computed with the Martin-curve, with a particle-based parameterization, and with sediment-trap data. Owing to the temperature dependence of the decay rate (Q₁₀ = 4.28), the jelly-POM export ratio below 500 m is 20–45% larger in subpolar and temperate areas than in the tropics. Vertical migration of gelatinous zooplankton leads to a variable starting depth of a jelly fall (death depth), which governs the start of remineralization, and the fate of the biomass. Owing to the absence of observations, we employ a sinking speed matrix ranging from 100 m d^-1 to 1500 m d^-1 to represent slow- and fast-sinking carcasses. The assumption of a constant decay rate k independent of temperature in other particle-based models may not be appropriate. These results provide information for including jelly-POM in global biogeochemical model formulations.