Banca de DEFESA: DHALTON LUIZ TOSETTO VENTURA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : DHALTON LUIZ TOSETTO VENTURA
DATA : 21/12/2018
HORA: 09:00
LOCAL: Sala de Videoconferência do PoP-RN
TÍTULO:

Water quality and temporal dynamics of the phytoplankton biomass in man-made lakes of the Brazilian semiarid region: an optical approach

PALAVRAS-CHAVES:

water quality; phytoplankton; biomass; temporal dynamics; hydraulic regime; monitoring; remote sensing; lakes; semiarid; Brazil.

PÁGINAS: 130
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

All over the world, scientists, managers and policy-makers have been challenged by several ecological and economic issues caused by the artificial eutrophication of lakes, whose most visible effect is the excessive phytoplankton biomass, commonly represented by the chlorophyll a concentration (chla). While nutrients play a primary role in the temporal dynamics of the phytoplankton biomass, the lakes’ hydraulic regime can exert an external control over such dynamics. In this study, we assessed the influence of the hydraulic regime on the temporal dynamics of the phytoplankton biomass in man-made lakes of the Brazilian semiarid region. Lakes are a crucial source of water resources for human consumption and irrigation in that region, but they are frequently affected by eutrophication and lack an adequate limnological monitoring. To overcome this data deficiency, we assessed the relationships among water quality and optical properties in 13 lakes of the study region, validated an algorithm for estimating chla from images of the MODIS orbital sensor, and generated a 15-year time series for the three largest study lakes: Orós (OROS), Castanhão (CAST) and Eng. Armando Ribeiro Gonçalves (EARG). Because lakes in the Brazilian semiarid region are subject to a seasonally marked hydraulic regime, we hypothesized that it would be reflected on the temporal variation of chla. The comparison between the time series of chla and lakes’ volume supported such hypothesis. The concentrations steeply dropped with intense rainfall-driven water renewal and kept high during the dry periods. The intense rainfall of 2004 abruptly reduced the phytoplankton biomass in EARG and OROS lakes and, for the latter, its effects even extended to the subsequent years. Our results encourage the exploration of the MODIS archived imagery for further studying the temporal dynamics of the phytoplankton in natural and man-made lakes, at both seasonal and interannual scales.

MEMBROS DA BANCA:
Externo à Instituição - JEAN-MICHEL MARTINEZ - IRD
Presidente - 1362202 - JOSE LUIZ DE ATTAYDE
Interno - 1345773 - RENATA DE FÁTIMA PANOSSO
Externo à Instituição - THIAGO SANNA FREIRE SILVA - UNESP
Externo ao Programa - 350698 - VENERANDO EUSTAQUIO AMARO