Influence of cyclonic and anticyclonic eddies on plankton in the southeastern Mediterranean Sea during late summertime

Abstract. Planktonic food webs were studied contemporaneously in a mesoscale cyclonic (upwelling, ? 13 months old) and an anticyclonic (downwelling, 2 eddy as well uninfluenced background situation the oligotrophic southeastern Mediterranean Sea (SEMS) during late summer 2018. We show that integrated nutrient concentrations higher cyclone compared to anticyclone or stations by 2–13-fold. Concurrently, Synechococcus Prochlorococcus dominant autotrophs abundance-wise (? 300 × 1010 cells m?2). In cyclone, functional groups such dinoflagellates, Prymnesiophyceae Ochrophyta contributed substantially total phytoplankton abundance 14 m?2), which was 65 % lower at 5 Primary production highest (191 mgCm-2d-1) 2–5-fold outside area. Heterotrophic prokaryotic cell-specific activity 10 fgCcell-1d-1), while least productive found (4 fgCcell-1d-1). Total zooplankton biomass upper m 10-fold with (1337 vs. 112–133 mg C m?2, respectively). Copepod diversity much (44 species), (6 small-size species). Our results highlight eddies significantly different community structure food-web dynamics environments, cyclones representing oases marine desert of SEMS.