Name: Fabrício Bronzoni de Oliveira
Type: MSc dissertation
Publication date: 03/03/2020
Advisor:
Name |
Role |
|---|---|
| Stéfano Zorzal de Almeida | Co-advisor * |
| Valéria de Oliveira Fernandes | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Lucineide Maria Santana | External Examiner * |
| MARCOS THIAGO GAUDIO GOMES | External Alternate * |
| MARIELA MATTOS DA SILVA | Internal Examiner * |
| Stéfano Zorzal de Almeida | Co advisor * |
| Valéria de Oliveira Fernandes | Advisor * |
| Viviana Borges Corte | Internal Alternate * |
Summary: Knowledge about the primary productivity process is of fundamental importance for understanding the metabolism and energy dynamics in natural ecosystems. Thus, the present study aimed to analyze the effects of three wavelength bands (blue, green and red), on the primary productivity of the phytoplankton community in the UFES lagoon, at Goiabeiras campus, Vitória (ES). The experiment was performed in triplicate (n=3), using the light and dark flasks method, with the light filters being applied to the light flasks. Transparent filter and control treatment (without filter application) were also used. The sampling frequency was monthly, in an annual cycle, in the central area of the lagoon. The primary productivity was assessed by the Winkler method and the data were expressed in mgO2.L-1.h-1. The phytoplankton community was evaluated in relation to richness, density, biovolume, frequency of occurrence and abundant and dominant taxa and biomass was evaluated based on chlorophyll a, b and c concentrations. The PCA was applied for temporal ordering of the samples and the Mann-Whitney test (p <0.05) was applied to check for seasonal differences. The Spearman correlation was applied between the values of gross (GPP) and net (NPP) primary productivity and the algal biovolume and the differences among treatments was evaluated by the Kruskall-Wallis test (p<0.05). The PCA and the Mann-Whitney test did not show seasonality for the studied environment. The phytoplankton community was composed of 43 taxa and five classes, with Cyanobacteria being the most prominent (24 taxa), followed by Chlorophyceae (15 taxa). Cyanobacteria showed higher density and biovolume, sometimes reaching 100% of the total density and biovolume. The highest average values of primary productivity were recorded in the red light range, for both GPP and NPP, being statistically higher than the values recorded for the blue and green light range. The increase in primary productivity in the red range was positively correlated with the Cyanobacteria biovolume. Our results showed evidence that red light range is the most efficient for increasing primary productivity in a community dominated by Cyanobacteria.
Keywords: Wavelengths; Light radiation, Oxygen production.
