Banca de DEFESA: ALAN SILVA ALVES BASTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ALAN SILVA ALVES BASTOS
DATE: 26/04/2024
TIME: 09:00
LOCAL: on-line
TITLE:

Environmental influences on the structure of fish assemblage on sandy beaches of Ilha Grande Bay – RJ

KEY WORDS:

Landscape ecology, Habitat structure, Ichthyofauna

PAGES: 103
BIG AREA: Ciências Biológicas
AREA: Zoologia
SUBÁREA: Zoologia Aplicada
SUMMARY:

Coastal ecosystems are threatened by multiple disturbances, demanding an expansion in the
knowledge of natural and anthropogenic factors that influence the composition and structure
of fish assemblages. The objective of this study was to investigate the variation in the fish
assemblage of sandy beaches in the Ilha Grande Bay (BIG) in relation to surrounding habitats,
physicochemical variables of water, and physical structure of environments. Bimonthly
samplings over two years (2017-2019) were conducted in three regions of BIG, namely the
Ribeira Bay (BR), Central Bay (BC), and Paraty Bay (BP), using beach seine nets. The
percentage of habitat mosaic coverage (HMC) (mangrove, anthropized area, urban area, rocky
outcrop, sandy ridge, vegetation, pasture, and sandbanks) was recorded within a radius of 2.2
km from each sampled beach. BR was the region with the highest coverage of urban area
(35.12%), followed by BP (8.9%) and BC (0.13%). Among the three regions, BR presented
beaches with shallower depths, higher water temperatures and transparency, as well as
concentrated mangrove areas on some beaches. BC recorded higher coverage of rocky
outcrop and sandy ridge, beaches with greater depths and water transparency. BP was
characterized by the presence of estuaries near the beaches, mangroves present in all sampling
points, higher turbidity rates, chlorophyll, and lower levels of dissolved oxygen. A total of
60.232 individuals were recorded (30,052 BP, 5,418 BC, and 24,762 BR), belonging to 96
taxa (77 BP, 55 BC, and 57 BR). Anchoa spp., Atherinella brasiliensis, and Anchoa januaria
were the most abundant taxa (87.95% of total abundance), especially due to the presence of
post-larval stages. In addition to these, Cathorops spixii (1.9%), Mugil liza (5.1%), and
Eucinostomus argenteus (1.5%) were abundant in BP, BC, and BR, respectively. The
structure of the fish assemblage varied from a more diverse assemblage associated with
shallower and more turbid beaches in BP, to less diverse assemblages associated with deeper
beaches in BC and greater transparency and anthropogenic matrix in BR. Variation in the
abundance of selected families and estuarine use groups were partly associated with the life
history of species, denoting proximity to estuaries (e.g., Atherinopsidae), mangrove
formations and turbidity (e.g., Ariidae), and distance to open sea (e.g., Mugilidae). Tolerance
to more anthropized environments (e.g., Atherinopsidae) or with high HMC (e.g., Carangidae)
also influenced abundance, while shallower depth was important for several groups (e.g.,
Carangidae, Engraulidae, Mugilidae, Marine Migrants, Marine Residents). This study reveals
the importance of including HMC for spatial and temporal understanding of fish assemblages
on sandy beaches considering increasing anthropization. If proper protection and conservation
measures for coastal mosaics are not taken, it is expected that the juvenile fish assemblage in
the BIG will become increasingly homogeneous and characterized by few generalist/tolerant
species. Investigating the effects of HMC on biota and monitoring its uses is essential for the
development of more efficient management measures.

COMMITTEE MEMBERS:
Interno - 2143107 - LEONARDO MITRANO NEVES
Externo ao Programa - 1494219 - ALEXANDRE FERREIRA LOPES - UFRRJExterno ao Programa - 1931586 - SADY JUNIOR MARTINS COSTA DE MENEZES - UFRRJExterno à Instituição - ANDRÉ LUIZ MACHADO PESSANHA - UEPB
Externa à Instituição - BIANCA DE FREITAS TERRA - UVA-CE