Appendicularians and marine snow in situ vertical distribution in Argentinean Patagonia

GIMÉNEZ, ELOÍSA MARIANA; NOCERA, ARIADNA CELINA; TEMPERONI, BRENDA; WINKLER, GESCHE

JOURNAL OF PLANKTON RESEARCH

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2022

0142-7873

etailed in situ vertical and temporal distribution of appendicularians, marine snow, fecal pellets, nano and microplankton were recorded simultaneously with environmental data in Argentinean Patagonia (San Jorge Gulf, 45º-47ºS). Data were taken at a fixed station during 36 h in February 2014 with an autonomous Video Plankton Recorder and FlowCAM®. Water column was thermally stratified with a pycnocline at ~40 m. Appendicularians (likely Oikopleura spp.) occurred in the upper 65 m with a condensed pattern above the pycnocline, matching the subsurface chlorophyll maximum layer (around 20 m). The lack of differences between day and night suggests the absence of vertical migration. Marine snow, strongly correlated with appendicularians, concentrated above the pycnocline at high concentrations, while fecal pellets (mostly from krill) distributed throughout the water column. Discarded houses of appendicularians or their mucus fragments were the main components of marine snow aggregates, phytoplankton, detritus and krill pellets also contributing. Nanoplankton (mostly degraded cells at bottom) predominated over microplankton, with patterns depending on local grazing pressure and advective processes. Our study, the first one in the region using underwater imagery, emphasizes the leading contribution of appendicularians to marine snow aggregates in the San Jorge Gulf and their potential implications in the bentho-pelagic coupling.