Benthic and Pelagic Contributions to Primary Production: Experimental Insights From the Gulf of Trieste (Northern Adriatic Sea)

Although the 14C-method remains one of the most sensitive measures of primary production in marine ecosystems, few data from coastal sublittoral areas are available. We applied an integrated approach to quantify the benthic (PPs) and pelagic (PPw) contributions to total primary production (PPt) in a 17-m deep coastal site. From March 2015 to March 2019, we carried out 16 in situ experiments on a seasonal basis, at the LTER site C1, whereas benthic rates were estimated in the laboratory. To relate PP to seawater physical features and to the water column stability, the Brunt-Väisälä frequency was calculated. We further related our PP rates to the abundance, biomass, main taxonomic groups and diversity of eukaryotic phytoplankton and microphytobenthos (MPB). In November 2018, the maximum PPw (6.71 ± 0.82 µgC L-1 h-1) was estimated at the surface layer, in correspondence to the highest value of dinoflagellates biomass (29.35 µgC L-1), on the account of small (<20 µm) naked and thecate form...