Including filter-feeding gelatinous macrozooplankton in a global marine
biogeochemical model: model-data comparison and impact on the ocean
carbon cycle
Corentin Clerc

LMD / IPSL, Ecole normale supérieure / Université PSL, CNRS, Ecole Polytechnique, Sorbonne Université, Paris, France, LMD / IPSL, Ecole normale supérieure / Université PSL, CNRS, Ecole Polytechnique, Sorbonne Université, Paris, France
Corresponding Author:corentin.clerc@lmd.ens.fr
Author ProfileFabio Benedetti

Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092, Zürich, Switzerland., Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092, Zürich, Switzerland.
Author ProfileAbstract
Filter-feeding gelatinous macrozooplankton (FFGM), namely salps,
pyrosomes and doliolids are increasingly recognized as an essential
component of the marine ecosystem. Unlike crustacean zooplankton (eg.,
copepods) which feed on prey that is an order of magnitude smaller,
filter-feeding allows FFGM access to a wider range of organisms, with
predator over prey ratios as high as 100 000:1. In addition, most FFGM
produce carcasses and/or fecal pellets that sink 10 times faster than
those of copepods. This implies a rapid and efficient export of organic
matter to depth. Even if these organisms represent <5% of the
overall planktonic biomass, the induced organic matter flux could be
substantial. Here we present a first estimate of the influence of FFGM
organisms on the export of particulate organic matter to the deep ocean
based on a marine biogeochemical earth system model: NEMO-PISCES. In
this new version of PISCES, two processes characterize FFGM: the
preference for small organisms due to filter feeding, and the rapid
sinking of carcasses and fecal pellets. To evaluate our modeled FFGM
distribution, we compiled FFGM abundances observations into a monthly
biomass climatology using a taxon-specific conversion. FFGM contribute
strongly to carbon export at depth (0.4 Pg C / yr at 1000m),
particularly in low-productivity region (up to 40% of POC export at
1000m) where they dominate macrozooplankton by a factor of 2. This
export increases in importance with depth, with a simulated transfer
efficiency close to one.