Banca de QUALIFICAÇÃO: EDSON SERAFIM DE ALMEIDA JÚNIOR

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : EDSON SERAFIM DE ALMEIDA JÚNIOR
DATE: 28/11/2023
TIME: 14:00
LOCAL: Virtual
TITLE:

Over time: Assessing the leaf litter decomposition pattern in an Atlantic Forest stream

KEY WORDS:

Headwater streams, decomposition, temporal pattern

PAGES: 58
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUBÁREA: Ecologia de Ecossistemas
SUMMARY:

Decomposition is a key process in nutrient and carbon cycling in headwater streams, where sunlight is limited, reducing aquatic primary productivity. In this context, the input of allochthonous organic matter, primarily leaves, is the main source of resources and energy. Differences in leaves' physical and chemical characteristics affect decomposition rates, influenced by the plant community's composition. Additionally, the chemical properties of the water play a crucial role in affecting the decomposer community. Aquatic hyphomycetes are key fungi in decomposition, producing enzymes that degrade organic matter, making it palatable for other organisms, such as shredding invertebrates. These invertebrates are fundamental in converting coarse particulate organic matter into fine and dissolved matter. Seasonality and precipitation also affect decomposition, leading to changes in the diversity of the decomposer community and decomposition rates over time. Long-term studies are crucial to understanding the decomposition patterns in headwater streams. This thesis aims to evaluate the decomposition pattern in an Atlantic Forest stream over 5 years, considering the influence of seasonality, organic matter quality, and climatic variables. The thesis is divided into three chapters with the following objectives: (I) evaluate the structure of the aquatic hyphomycetes community over five years. (II) Assess and establish a pattern in the dynamics of organic matter decomposition over time. (III) Evaluate the effect of the functional diversity of the decomposer community (hyphomycetes and shredders) on the decomposition of allochthonous organic matter in the studied stream. The experiments were conducted in Serra da Jibóia, Bahia, between January 2015 and January 2020, in a second-order stream. The stream was divided into three points with a 40m distance between them. Buckets were set up to collect leaves. From these buckets, decomposition experiments were set up quarterly. The buckets with the most leaf weight were incubated in decomposition bags. The bags were removed monthly at intervals of 30, 60, and 90 days after incubation. The decomposer community was identified from the samples, and procedures for decomposition coefficient calculations were carried out. 23 species of aquatic hyphomycetes and 53 families of invertebrates associated with decomposing leaves were found. For the structure of the aquatic hyphomycetes community (Chapter 1), we found the influence of pH, ammonia, nitrite in the water, and nitrogen and phosphorus in the leaves. No interannual differences were found in the studied years. Within the aquatic hyphomycetes community, only Anguillospora longissima, Tricelophorus monosporus, and Tricelophorus acuminatus were sensitive to changes in the mentioned variables. The study provides long-term evidence of changes in the hyphomycetes community under alterations in the main environmental parameters affecting the decomposition process over time. Chapters II and III contain all the data that has already been collected, processed, and tabulated and will be worked on in collaboration with Professors Scott Tiegs and Nicole Wagner at Oakland University in the USA during the sandwich Ph.D. program scheduled to start in January 2024.

COMMITTEE MEMBERS:
Presidente - 1658906 - ADRIANA OLIVEIRA MEDEIROS
Interno - 3062840 - BRUNO VILELA DE MORAES E SILVA
Externo à Instituição - MARCELO DA SILVA MORETTI