Banca de DEFESA: SELMA MARIA DE ARRUDA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : SELMA MARIA DE ARRUDA SILVA
DATE: 18/06/2025
TIME: 09:00
LOCAL: Auditório Milton Santos (CEGEA/UNIR)
TITLE:

COMPLEX GEOENVIRONMENTAL INTERACTIONS: SUPPLY OF MICROPLASTICS IN THE WESTERN AMAZON

KEY WORDS:

Microplastics; Aquatic ecosystems; Bioindicators; Protozoa; Territorial planning

PAGES: 141
BIG AREA: Ciências Humanas
AREA: Geografia
SUBÁREA: Geografia Regional
SUMMARY:

The increasing production and disposal of synthetic polymers have intensified diffuse pollution in aquatic ecosystems, making microplastics (MPs) widespread and persistent emerging contaminants. This postdoctoral research investigated the spatiotemporal distribution of MPs and their ecological interactions with aquatic bioindicator organisms—zooplankton, cyanobacteria, and free-living ciliated protozoa—in freshwater bodies of the Eastern Mesoregion of Rondonia, Brazil. The study encompassed urban streams, aquaculture effluents, and protected watercourses across four municipalities: Ji-Parana, Rolim de Moura, Ouro Preto do Oeste, and Urupa. The methodological design consisted of a fully randomized factorial structure (3 environments × 2 hydrological seasons), with triplicate sampling and standardized procedures based on NOAA protocols. MPs were extracted from 500 mL water samples using 6.0 mm mesh sieves, morphologically and chromatically classified, and quantified with a Neubauer counting chamber. Zooplankton and protozoa were identified using binocular optical microscopy (400x) and digital stereoscopy, supported by photomicrography and image analysis software. Organism densities were expressed in individuals per mL (Ind.mL⁻¹), and data were analyzed using Student’s ttest and the Scott-Knott grouping method. Results showed ubiquitous presence of MPs in all sampled environments, with the highest concentrations observed in urban and aquaculture sites. Transparent fibers were the predominant morphology, suggesting secondary origin through environmental degradation of plastic waste. Zooplankton communities were rich and diverse, with Rotifera, Copepoda, and Ostracoda as the most abundant taxa, especially in aquaculture effluents. Cyanobacteria density increased significantly during the rainy season, indicating hydrological influence on phytoplankton dynamics. Free-living ciliates, notably Spirostomum teres, Paramecium bursaria, and Halteria grandinella, were more abundant in the dry season, showing sensitivity to organic matter concentration and oxygen variation. The observed replacement of sensitive taxa by more tolerant species in impacted environments revealed an ecological degradation pattern, where MPs serve as modulators of aquatic microbial communities. These microorganisms proved to be effective bioindicators of water quality variation and ecological integrity loss. The integrated geosystemic approach allowed the identification of territorial dynamics—such as land-use intensification, urbanization, and aquaculture practices—as key drivers of MP pollution and microbial biodiversity shifts. In conclusion, MPs not only function as spatial markers of anthropogenic alteration but also impact fundamental ecological processes in freshwater systems. This research underscores the importance of incorporating ecological variables into environmental cartography and territorial planning, particularly in tropical regions, where MPs should be considered key indicators of environmental degradation at microecological scales.

COMMITTEE MEMBERS:
Presidente - 1680831 - ADRIANA CRISTINA DA SILVA NUNES
Externo à Instituição - FRANCISCO CARLOS DA SILVA - São Lucas
Interno - ***.118.225-** - JULIEN MARIUS REIS THEVENIN - UNESP
Interno - 2313615 - MICHEL WATANABE
Interno - 1692690 - RANIERE GARCEZ COSTA SOUSA
Interno - 2374782 - RICARDO GILSON DA COSTA SILVA