Banca de QUALIFICAÇÃO: MAIARA MENEZES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : MAIARA MENEZES
DATA : 31/10/2017
HORA: 13:00
LOCAL: SALA DE REUNIÃO DO CENTRO DE BIOCIÊNCIAS
TÍTULO:

Temporal dynamic of picoplankton in a coastal site of the Equatorial Atlantic Ocean

PALAVRAS-CHAVES:

picoplankton, microbial metabolism, time series, tropical Atlantic ocean.

PÁGINAS: 30
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Picoplankton is composed of autotrophic and heterotrophic microorganisms (< 3µm) and plays an important role in aquatic ecosystems being responsible most part of nutrient cycling and primary production in oceans. Due to low climatic variation and its small size, picoplankton has adaptive advantages over nanoplankton in tropical oligotrophic oceans. Despite their relevance, few studies evaluate the temporal dynamics of the microbial community in tropical oceans. In this context, the present study aims to evaluate seasonal dynamic (abundance and metabolism) of picoplankton and to identify the environmental factors that regulate it in Equatorial Atlantic Ocean. We collected seawater samples monthly between 2013 and 2016 on the sampling station on the coast of RN state - Brazil. We determined abundance of autotrophic picoplankton (Synechococcus and Picoeukaryotes) and heterotrophic bacteria (Heterotrophic Bacteria) through the analysis of water samples by flow cytometry, and estimated metabolic rates of bacterial production and respiration. In addition, we collect environmental data in situ and via satellite. We also analyzed the concentration of dissolved nutrients. Our results revealed that in average 60% of total chlorophyll a is relative to picoplankton (47-73%). We detected no seasonal variation in the abundance of the community, neither in the microbial metabolism, both evaluated by the decomposition of the time series and by ANOVA comparing dry and rainy months. Chlorophyll a was the only variable that showed a seasonal tendency, with higher concentrations in the rainy months (F = 3.64, p = 0.06). Heterotrophic bacteria were positively correlated with Synechococcus (β = 0.890, p <0.001) and Picoeucariotos (β = 0.390, p = 0.016). Salinity was negatively correlated with all community components and with chlorophyll a. Phosphorus was important affecting negatively the HB (β = 0.09, p = 0.03), while Nitrogen had a greater effect on Picoeukaryotes (β = 4.69, p = 0.001). We concluded that there were no effects of climatic seasonality on the temporal dynamics of picoplankton in the study area. Salinity can be an important factor influencing the community. Although the weak environmental relationships found may suggest a greater importance of biological interactions leading to low amplitude fluctuations throughout the year.

MEMBROS DA BANCA:
Presidente - 1639731 - ANDRE MEGALI AMADO
Externo ao Programa - 2412921 - JULIANA DEO DIAS
Externo ao Programa - 2326316 - NG HAIG THEY