Banca de DEFESA: MARIA MIRTES DE LIMA PINHEIRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MARIA MIRTES DE LIMA PINHEIRO
DATE: 05/06/2023
TIME: 10:00
LOCAL: Campus de Rolim de Moura- sala 21
TITLE:

Monitoring of cyanobacteria in the water of fish ponds in the interior of Rondônia.

KEY WORDS:

Aquatic Ecotoxicology.Cyanophytes. Cyanotoxins. Environmental Biomonitoring.

PAGES: 75
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

Aquatic pollution causes the excessive growth of cyanobacteria, systematically in fish farming results in the death of fish, due to the deficit of dissolved oxygen and the synthesis of toxins. Therefore, the aims of this study were to carry out qualitative and quantitative analyzes of cyanobacteria, record blooms and estimate their ecotoxicological potential in water from fish ponds. The study was carried out in 20 fish farms in the interior of the Rondônia state. Samplings were carried out in the rainy and dry season. The experiment was developed in a completely randomized factorial design 20 x 3 x 3 (20 fish farms, 3 ponds and 3 replications). For the composition of the qualitative samples, horizontal and vertical drags were carried out on the surface of the water. While each quantitative sample was obtained in a plankton net (50 μm mesh opening). With a multiparametric probe the quality of the water was verified. Cyanobacteria were classified taxonomically and blooms were recorded. Blood was collected from 60 tambaquis, in the dry and rainy seasons, for conditions with or without cyanobacterial bloom. Water quality, relative abundance, seasonal variation, spatial variation and potential for toxin synthesis were statistically analyzed using Pearson's correlation test. To contrast averages of variables between hydrological stations, Student's t test was applied (α= 0.05).Rainfall fluctuations influenced the quality of water in the ponds, abundance and flowering. Fifteen families and 29 species of cyanobacteria were identified. The species that showed the highest abundances were Microcystis aeruginosa, Planktolyngbya limnetica, Planktothrix sp. and P. agardhii. The cyanobacterial community showed higher levels of richness, diversity and dominance right after the rainy season, allowing the coexistence of the species. Blooms of Microcystis aeruginosa, M. flos-aquae, Planktothrix sp., P. agardhii, Planktolyngbya limnetica and Oscillatoria sp. A total of 20 blooms were found, 18 in the dry season and only 2 records in the rainy. Fish farms 1 and 4 exceeded the density limit allowed by law by more than 10 times. In the dry season, all blooms showed some significant ecotoxicological risk. The micronucleus test (Mn) and other abnormalities in the tambaqui blood were also performed. A greater number of abnormalities were observed during the dry season and in fish submitted to ponds with cyanobacterial blooms. The results obtained in this study reinforce the need for monitoring the water quality of fish ponds as well as the qualitative and quantitative analysis of the planktonic community.

COMMITTEE MEMBERS:
Externo à Instituição - ANA CLAUDIA OLIVEIRA CARREIRA NISHIYAMA
Externo à Instituição - RAPHAEL BRITO DOS SANTOS
Externo à Instituição - JERONIMO VIEIRA DANTAS FILHO - UNIR