Temporal dynamic of picoplankton in the western coast of equatorial Atlantic Ocean

MENEZES, MAIARA; WANDERLEY, B. M. S.; KAVAGUTTI, V.; UNREIN, F.; AMADO, A.; SARMENTO, H.

Chascomús

Taller; 2do Taller de la Red colaborativa en Ecología Microbiana Acuática en América Latina (μSudAqua); 2019

Picoplankton are small central players of global C cycling and often dominate plankton community in lowlatitude oceans. Evaluate picoplankton temporal dynamics is critical to understand microbial stocks and C fluxes in the tropical ocean. Thus, we performed monthly samplings between 2013-2016 at the Equatorial Atlantic Microbial Observatory (EAMO) located on the coast of RN state ? Brazil to evaluate time variations in abundance, biomass and metabolism (bacterial production and respiration) of picoplankton assemblage, and also environmental factors that may regulate picoplankton in this coastal region. Our results revealed great stability in seasonal dynamic of picoplankton, despite considerable interannual variation most related to El Niño (ENSO) event in 2015. Heterotrophic bacteria dominated picoplankton during the entire study period, whereas autotrophic picoplankton (Synechococcus spp. and picoeukaryotes) contributed in average for 30% of total picoplankton biomass. Greater abundances of total picoplakton community were registered during periods of low salinity. However, weak environmental relationships founded may suggest a greater importance of biological interactions leading to picoplankton fluctuations. This evidence provides a perspective that picoplankton may exhibit more pronounced fluctuations in interannual intervals in the tropical region, but it is of permanent relevance for C cycling, especially in a climate change scenario.