Banca de DEFESA: JÉSSICA DA SILVA AZEVEDO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : JÉSSICA DA SILVA AZEVEDO
DATA : 28/02/2020
HORA: 08:30
LOCAL: Sala 107, unidade Amazônia
TÍTULO:

Diversity of periphytic diatoms (Bacillariophyta) in the Curuá Una reservoir (Santarém, Amazon, Brazil).

PALAVRAS-CHAVES:

Periphytic communities, diatoms, reservoir, Curuá-Una.

PÁGINAS: 135
GRANDE ÁREA: Ciências Biológicas
ÁREA: Botânica
SUBÁREA: Taxonomia Vegetal
ESPECIALIDADE: Taxonomia de Criptógamos
RESUMO:

The Curuá-Una Hydroeletric plant, located south of the city of Santarém-PA, was built in the 70s and was the first in the region. The construction of hydroelectric plants, and consequently the reservoirs that form part of them, substantially interfere with the physical, chemical and biological characteristics of the aquatic system, affecting water quality. Therefore, knowledge of aquatic organisms and the food chain of a reservoir is of great importance, because the presence or absence of certain species and the composition of existing communities serve as indicators of the “status” of water quality. The diatoms are main algae in the periphytic communities. In addition to the fundamental contribution to the trofic chain, they can also be used efficiently in the assessment of environmental conditions in rivers, streams, reservoirs and lakes. Aiming to investigate the composition (floristic survey) of the periphytic diatom community of the Curuá-Una reservoir (Santarém-PA), as well as analyzing the distribution of this community of periphytic algae in the river and Curuá-una reservoir in relation to abiotic data,
this study carried out collections between the months of May 2016 and April 2017 in six different sites, distributed over of the Curua-Una reservoir (transiotional zone/ influence lotic places), mouth of the Moju and Mojui rivers (transiotinal zone/ influence lotic environment) and reservoirs (lake zone) in two periods (less rainy and rainy) totaling 24 samples. Measurements were taken in each sampling in situ of physical and chemical varieties of water, like: depth (m), water transparency (m), water temperature (ºC), dissolved oxygen (DO: mg.L^-1), conductivity (μS.cm^-1), and pH were also measured with aid of the probe multiparameter AKSO model AK88. The environmental variables such as: turbidity (NTU), Ammonium (mg. L^-1), Nitrate (mg. L^-1), Phosphorus (mg. L^-1), Silicate (mg. L^-1) and biochemical demand –BOD (mg. L^-1) were also measured. Periphytic diatoms were obtained using artificial substrates (samplers) type EDS (Epilithic Diatom Sampler)
In total, 172 taxa were recorded throughout the sample, belonging to 34 genus and 21 families. The most representatives’ genus was Eunotia Ehrenberg (57%), Gomphonema Ehrenberg (15%), Frustulia Rabenhorst (15%) and Encyonema Kützing (13%). The Shannon diversity ranged from H’=1,51 to H’=3,18 in the reservouir in the rainy season between H’= 1,68 to H’= 3,09 from less rainy season. Among the variables evaluated in this study, electrical conductivity was the environmental variable most altered in the rainy season by the degradation conditions found throughout the reservoir. The results PERMANOVA and the PCO revealed the existence of a spatial pattern between the samplers, and that diatoms community is structured in three distinct groups. Canonical correspondence analysis showed that the composition of the periphytic diatoms is strongly associated by the environmental variables conductivity, pH, BOD, ammonium, silica, temperature and transparency. It was also possible to observe that most of the registered species were considered rare, some species stood out as sporadic and few were considered frequent or constant. The results observed in the present study showed a high diversity of taxa throughout the sample when compared with other studies carried out with EDS type samplers in Brazil, in addition, it provided a better understanding of the floristic composition of the periphery in Amazonian aquatic environments. The Curuá-Una reservoir is relatively preserved, however it shows signs of mild to moderate degree of anthropic influence, which are associated with the inadequate use of the soil around this aquatic environment.

MEMBROS DA BANCA:
Externo ao Programa - 1544196 - DIEGO MAIA ZACARDI
Interno - 1520271 - JOAO RICARDO VASCONCELLOS GAMA
Interno - 2143267 - JOSE MAX BARBOSA DE OLIVEIRA JUNIOR
Externo ao Programa - 1562643 - MAXWELL BARBOSA DE SANTANA
Presidente - 1693122 - SERGIO DE MELO
Interno - 1776327 - THIAGO ALMEIDA VIEIRA