Dynamics of picoplankton community from coastal waters to the open sea in the Central Adriatic

Abstract

Flow cytometry was used to describe seasonal cycles of Prochlorococcus (Prochl), Synechococcus (Syn), picoeukaryotes and heterotrophic bacteria in the central Adriatic Sea along the trophic gradient from January to December 2010. All picoplankton parameters decreased from eutrophic to oligotrophic areas, while the biomass ratio of bacterial to autotrophic picoplankton showed an increase along the trophic gradient. Bacterial biomass ranged from 5.28 to 21.20 μg C l-1. Increased values were present during warmer seasons with the domination of low nucleic acid (LNA) group of bacteria. The high nucleic acid (HNA) bacterial group dominated during the winter and the spring. Bacterial production ranged from 0.09 -0.45 × 104 cells ml-1 h-1 .At coastal stations increased production was present during the winter and the spring and was more or less uniform at open sea stations. Biomasses of Syn and Prochl ranged from 0.16 to 11.47 µg C-1 l-1 and from 0.01 to 3.08 µg C l-1, respectively. They were elevated during the summer and the autumn at coastal stations and during the late winter at the open sea. Syn biomass always dominated over Prochl participating with 61.6-97.2% in biomass of cyanobacteria. Biomass of picoeukaryotes ranged from 1.21 to 21.85 µg C l-1 and was the highest during the winter. Their biomass notably prevailed in autotrophic picoplankton (APP) biomass over that of picocyanobacteria during the whole year. Autotrophic components (Prochl, Syn and picoeukaryotes) made greater contribution to the picoplankton biomass in mesotrophic and eutrophic areas, while heterotrophic bacteria became more important under oligotrophic conditions.

Effects of fish farming on microbial planktonic communities in the middle Adriatic sea

“…On the other hand, nitrate concentrations were higher than in the aforementioned studies implying different structure of the nutrient pool between these two basins. The concentrations of measured nutrients at the Farm are comparable with the values commonly found in the Adriatic Sea for the locations that are not under the aquaculture influence (Ivančić, Fuks, Najdek, Blažina, Devescovi, Šilović, Paliaga & Orlić ; Fuks, Ivančić, Najdek, Lučić, Njire, Godrijan, Marić, Šilović, Paliaga, Blažina, Precali & Orlić ; Šantić, Šestanović, Šolić, Krstulović, Kušpilić, Ordulj & Ninčević ). Thus, the general assumption that continuous nutrient loadings from fish farms could have serious effects on natural occurring nutrient concentrations, particularly in the oligotrophic environment does not appear to be the case here.…”

“…These cells commonly prevail in phosphate‐depleted environments like the Adriatic Sea (Civitarese, Gačić, Vetrano, Boldrin, Bregant, Rabitti & Souvermezoglou ; Socal, Boldrin, Bianchi, Civitarese, De Lazzari, Rabitti, Totti & Turchetto ; Ninčević, Marasović, Kušpilić, Krstulović, Šolić & Šestanović ; Šantić et al . ). Although the ecological roles of LNA bacteria are still controversial, the recent investigations point to the relevant conclusion that nutrient uptake efficiency is probably the key factor for LNA bacteria to dominate over HNA bacteria in phosphate‐limiting environments (Nishimura et al .…”

Changes in the Trophic Pathways within the Microbial Food Web in the Global Warming Scenario: An Experimental Study in the Adriatic Sea

“…Such picoplankton biomass distribution is in accordance with HNA (within heterotrophic prokaryotes) and PE (within autotrophic picoplankton) dominance in coastal regions, particularly during a spring period with high supply of nutrients. On the other hand, LNA bacteria and CB (particularly PROC) preferred oligotrophic waters [4,[65][66][67][68], as they are better adapted to oligotrophic conditions [69,70]. An almost identical biomass distribution for picoplankton groups was found in the Galician coastal upwelling system as follows: HNA (55%), LNA (21%), PE (11%), SYN (6%), and PROC (1%) [71].…”

Diet Composition and Isotopic Analysis of Nine Important Fisheries Resources in the Eastern Adriatic Sea (Mediterranean)

“…The open Middle area (seven sampling stations; Figure 1) is characterized by a gradient of decreasing nutrient conditions from more productive coastal areas to oligotrophic open sea areas (Ninčević Gladan et al, 2006;Šantić et al, 2014). Moreover, the open sea is influenced by discharge of the nutrient-enriched river Po along the western coast, and it is also an area of upwelling (Bergamasco and Gačić, 1996;Gačić et al, 1997;Mauri and Poulain, 2001).…”