Name: Lorena Lopes Almeida
Type: MSc dissertation
Publication date: 20/02/2018
Advisor:
Name |
Role |
|---|---|
| Maurício Hostim Silva | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Agnaldo Silva Martins | Internal Alternate * |
| Ciro Colodetti Vilar de Araujo | External Alternate * |
| Igor Emiliano Gomes Pinheiro | External Examiner * |
| Jean-Christophe Joyeux | Internal Examiner * |
| Maurício Hostim Silva | Advisor * |
Summary: This study aimed to describe the eating habits and habitat use by Stellifer brasiliensis in the Environmental Protection Area (APA) of Conceição da Barra, Espírito Santo. For this purpose, analysis of stomach contents associated with the analysis of stable isotopes of carbon (δ13C) and nitrogen (δ15N) was performed. In order to evaluate the habitat use, the spatial distribution of abundance, biomass and total length (TL, mm) of the species were evaluated. The ichthyofauna was sampled monthly with bottom trawl nets at four areas distributed in a salinity gradient. For analysis of abundance, biomass and TL of
juveniles and adults, these occurred between May/2014 and April/2017; for the analysis of stomach contents, between July/2015 and July/2016; and for the analysis of stable isotopes, fish and prey were collected between March/2016 and March/2017. Primary producers were collected in the months of April, June, August, September and December/2016 and in June/2017. The species presented higher abundance (F = 4.586, p <0.005) and biomass (F = 7.139, p <0.005) at P4. The highest lengths were recorded in winter and fall in P1 and in spring and summer in P4. The most important food items
for the species were Polychaeta, Thalassinidae and Penaeidae, for juveniles were Penaeidae, Euphausiacea and Copepoda and for adults were Polychaeta, Thalassinidae and Copepoda. The δ13C values of S. brasiliensis were similar between the seasons, areas and ontogenetic phases and ranged from -17,45 ± 1,35 to -25,81 ± 0,67 in juveniles and -18,28 ± 3.09 to -23.29 ± 1.37 in adults, while the mean δ15N ranged from 12.73 ± 0.95 to 16.24 ± 0.32 in juveniles and 13.83 ± 1,39 to 16.29 ± 0.68 in adults. The means of δ15N indicated that both phases occupy the same trophic
level. The means of δ13C in juveniles and adults in P1 were similar to the values of δ13C in the crustaceans Xyphopenaeus kroyeri and Alpheidae, indicating that these are items consumed by both ontogenetic phases. There was a negative correlation between the δ13C values with the fish TL, indicating that when the fish grows, the value of δ13C decreases, while the correlation of δ15N was positive, indicating that when the fish grows, the value of δ15N increases.
Keywords: Spatial distribution, trophic ecology, diet, stable isotopes, bycatch
