Banca de DEFESA: TAILAN MORETTI MATTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : TAILAN MORETTI MATTOS
DATA : 01/06/2019
HORA: 09:00
LOCAL: Sala 34 do icbs
TÍTULO:

The use of taxonomic distinctness, functional diversity and trophic modeling as tools to evaluate fish assemblages in reservoirs with different hydro-environmental configurations

PALAVRAS-CHAVES:

Anthropic impact, aquatic ecosystems, functional redundancy, Ecopath, keystone species, non-native species, Paraíba do Sul River

PÁGINAS: 128
GRANDE ÁREA: Ciências Biológicas
ÁREA: Zoologia
SUBÁREA: Taxonomia dos Grupos Recentes
RESUMO:

The construction of reservoirs, blocking the lotic systems, creates physical barriers that
alter the flow regime and create new physic-chemical conditions in the new
environment, besides acting as a barrier, preventing the free migration of aquatic
organisms. The lentic environment also facilitates the introduction of non-native fish
species, causing local extinction of a large number of fish species, especially those
more specialized and less susceptible to new environmental conditions. The increasing
number of reservoirs in tropical rivers is threatening aquatic biodiversity on an
unprecedented scale, posing a major challenge for fish populations, especially for large
migrators. The objective of this work was to evaluate and compare fish assemblages in
eight reservoirs with different hydro-environmental configurations, associated to the
Paraíba do Sul river basin: 1) reservoirs that bar the main RPS channel; 2) Reservoir in
cascade derived from waater abstraction from RPS and, 3) reservoirs isolates. Three
approaches were used: functional and taxonomic distinction, functional diversity and
trophic modeling. Three approaches were used: functional and taxonomic distinction,
functional diversity and trophic modeling. To evaluate the functional, taxonomic and
functional diversity of the reservoirs, the fish community was sampled monthly in the
summer of 2011 and in the winter of 2017. Thirty measurements in fish (26
quantitative and four categorical), representing functional attributes associated with
locomotion, feeding, life strategy and habitat use were taken in 34 species of the
different reservoirs. The trophic modeling was elaborated only for the Ribeirao das
Lajes Reservoir (RRL), based on monthly sampling (September / 2015 to July / 2017) of
different consumer compartments (birds, zoobenthos and fish) and on available
information on producers, non-fish consumers and detritus. Two models were
constructed for the Ribeirao das Lajes Reservoir, being an annual model, representing
the scenario of high quota in the reservoir (MCA) and another additional model
representing an adverse condition, with reduced water quota in the reservoir (MCB).
Differences were detected in fish assemblages of the different types of reservoirs
(main channel, cascade and isolates). The number of species did not differ among the
reservoirs, except in Tocos, which was significantly smaller when compared to the
other reservoirs (F = 6.9 P <0.001). The highest taxonomic and functional
distinctiviness were found for the isolated reservoirs, and the inverse of this pattern
was found for the reservoirs that bblock the main channel of the Paraíba do Sul river.
This suggests that the fish fauna in these latter types of reservoir is probably composed
of species phylogenetically close and morphologically similar with greater taxonomic
and functional redundancy. The Santana reservoir, the first in the cascade system,
xiii
presented the highest levels of functional diversity, with high richness and functional
uniformity, low originality and high exclusivity. Contrary to the expectations, the Santa
Branca, Funil and Pombos Island reservoirs (built in the main channel of the Paraíba do
Sul River) presented the lowest values of these indices, suggesting high functional
redundancy. Tocos, despite being an isolated reservoir and smaller area, presented the
highest values of divergence and functional specialization. The matter and energy
brought by the inflow water providing a greater habitat diversity in the reservoirs that
block the main channel of the river do not seem to be the most important determinant
factors for the roles developed by the fish in the reservoirs. The models elaborated in
the RRL revealed that the main base compartments (producers) were Leaf-Seeds-Fruits
and Periphyton, surpassing Phytoplankton. The compartments of Selective Birds (NT =
3.8), Generalist Birds (NT = 3.7) and the species of piscivorous fish Hoplias malabaricus
(NT = 3.8) and Cichla spp. (NT = 3.6) presented the highest NTs estimated for the web.
The main key species of the system were generalist birds, and the fish R. quelen and H.
malabaricus. Cichla spp., even not being considered as a key species, presented high
relative biomass and high impact on the web, also showing great relevance for the
ecosystem. No differences were found in the trophic web between MCA and MCB,
with the biomass of some compartments varying between the scenarios modeled. The
Ancestry value was 25.9, with Overhead of 74.2, indicating that the RRL is a mature
ecosystem. Only 34 species were recorded in the eight reservoirs, seven of which were
non-native species (ENN). However, studies recorded the occurrence of 89 fish species
for the lotic stretches of the Paraíba do Sul River, a strong indication that reservoirs
actually act as filters, selecting species with specific attributes and facilitating the
establishment of ENN. Based on this study, it is suggested that the construction of
dams should be done only for the purpose of water supply and irrigation, and that they
do not block the main river channel, in order to avoid drastic influence on the services
provided by these lotic systems, thus contributing to the maintenance of biodiversity.
As an alternative to power generation, investments in clean energy sources are
suggested, but with less impact on the environment.

MEMBROS DA BANCA:
Externo ao Programa - 3020848 - ALBERT LUIZ SUHETT
Interno - 387200 - FRANCISCO GERSON ARAUJO
Externo à Instituição - LUISA RESENDE MANNA
Externo à Instituição - MIRIAM PILZ ALBRECHT
Externo à Instituição - RONALDO ANGELINI