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Master's Dissertation
DOI
10.11606/D.21.2016.tde-22032016-082331
Document
Author
Full name
Bianca Reis Castaldi Tocci
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2015
Supervisor
Committee
Ciotti, Áurea Maria (President)
Tenenbaum, Denise Rivera
Gianesella, Sonia Maria Flores
Title in Portuguese
Ocorrência e coexistência de cianobactérias diazotróficas no Canal de São Sebastião-SP com o aumento da pluviosidade
Keywords in Portuguese
Hemiaulus
Richelia intracellularis
Trichodesmium
Baía do Araçá
comunidade fitoplanctônica
diatomáceas
Abstract in Portuguese
A fixação de N2 é uma fonte importante de nitrogênio novo nos ciclos biogeoquímicos, realizado potencialmente por cianobactérias diazotróficas, principalmente em condições de limitação de nitrogênio. O canal de São Sebastião (CSS) é reconhecidamente meso-oligotrófico, porém, eventos episódicos de precipitação podem alterar as concentrações de nutrientes locais interferindo na ocorrência de diazotróficas. Este trabalho investigou o efeito do aumento da pluviosidade na ocorrência e coexistência de diazotróficas no CSS e na baía do Araçá (BA), em 9 cenários distintos. As diazotróficas Trichodesmium spp. e Richelia intracellularis ocorreram após o aumento da pluviosidade nos dois pontos, não co-existindo em dois eventos. R. intracellularis ocorreu somente em endossimbiose com diatomáceas do gênero Hemiaulus, com predomínio em H. membranaceus. Os ventos de SW no CSS indicaram relações diretas na ocorrência das diazotróficas, sugerindo advecção de células provindas de outros locais. A temperatura e o fosfato apresentaram relações significativas com a ocorrência das diazotróficas. As densidades de diazotróficas e da comunidade fitoplanctônica foram maiores na BA em todos os eventos, assim como as concentrações de clorofila-a e nutrientes, ressaltando a importância da interação das águas da BA com o CSS.
Title in English
Occurrence and co-existence of diazotrophic cyanobacteria in São Sebastião-SP channel with increasing rainfall
Keywords in English
Hemiaulus
Richelia intracellularis
Trichodesmium
Araçá Bay
diatoms
phytoplankton community
Abstract in English
The biological nitrogen fixation adds new nitrogen into the biogeochemical cycle. This process is attributed to diazothrophic cyanobacteria, which are known to occur in environments with nitrogen limitation. Although the São Sebastião Channel (CSS) is a meso-oligothrophic environment, local rain can affect nutrients concentrations, hence the occurrence of diazothrophic species. This work addressed how the increase in the precipitation rate alters the occurrence and co-existence of diazothrophic cyanobacteria in nine scenarios in the CSS and Araçá Bay (BA). The diazothrophic species Trichodesmium spp. and Richelia intracellularis occurred after an increase in rainfall, co-occurring in 7 of the 9 scenarios. Richelia intracellularis was always associated symbiotically with Hemiaulus diatoms, specially H. membranaceus. The occurrence of diazothrophic species was highly correlated to intense SW winds, suggesting the allochthonous input of cells in the CSS. The diazothrophic species occurrence was also associated with variations in temperature and phosphate concentration. The abundance of both diazothrophic species and phytoplankton community were higher in the BA in every scenario. The nutrients and chlorophyll-a concentrations were higher in the BA, highlighting the importance of water transport between BA and CSS.
 
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Publishing Date
2016-03-22
 
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