Food resource utilization of the skates Rioraja agassizii (Müller & Henle, 1841) and Psammobatis extenta (Garman, 1913) on the continental shelf off Ubatuba, South-eastern Brazil
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Data
2001-05-01
Autores
MUTO, E. Y.
SOARES, L. S. H.
GOITEIN, R. [UNESP]
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Editor
Instituto Internacional de Ecologia
Resumo
Os hábitos alimentares de Rioraja agassizii e Psammobatis extenta da região costeira de Ubatuba, SP, foram investigados por meio da análise de conteúdos estomacais. As amostras foram obtidas em oito campanhas oceanográficas sazonais realizadas no período de outubro de 1985 a julho de 1987. A importância do item alimentar foi avaliada pelo Índice de Importância Relativa e a sobreposição alimentar pela Porcentagem de Similaridade. As duas espécies se alimentaram de organismos bentônicos, principalmente crustáceos. Os Amphipoda, os camarões Caridea e os Brachyura foram as presas mais importantes. Além dessas presas, Teleostei foi importante na dieta de R. agassizii. A variação sazonal da alimentação das raias esteve associada à disponibilidade de suas presas, cuja distribuição e abundância estão relacionadas às variações sazonais das condições oceanográficas da região. A alimentação de jovens e adultos de P. extenta foi muito semelhante, enquanto jovens e adultos de R. agassizii apresentaram baixa similaridade alimentar na maioria das estações do ano. Caridea foi importante para todos os tamanhos de R. agassizii, Amphipoda para exemplares menores e Teleostei para indivíduos maiores. A sobreposição alimentar entre as duas espécies foi alta no outono de 1986 e nos invernos de 1986 e 1987.
The feeding habits of Rioraja agassizii (syn. Raja agassizii) and Psammobatis extenta (syn. Psammobatis glansdissimilis) of the South-eastern Brazilian coast were studied by means of stomach content analysis. The samples were obtained on eight seasonal oceanographic cruises, carried out between October 1985 and July 1987. The importance of each food item was evaluated on the basis of the Index of Relative Importance and the feeding similarity by Percentage of Similarity. The results indicated that both species are benthic feeders, preying mainly on Crustacea, especially Amphipoda, Caridea and Brachyura. Teleostei were also important for R. agassizii. Seasonal variation of the diet seems to be associated with the availability of the prey, whose distribution and abundance are related to the dynamics of the water masses of the region. Juveniles and adults of P. extenta exploited the same resources while juveniles and adults of R. agassizii presented low diet similarity during most of the year. Caridea were an important food for all length classes of R. agassizii, while Amphipoda were for smaller specimens, and Teleostei for larger ones. The feeding overlap between the two species was higher during autumn 1986, winter 1986 and winter 1987.
The feeding habits of Rioraja agassizii (syn. Raja agassizii) and Psammobatis extenta (syn. Psammobatis glansdissimilis) of the South-eastern Brazilian coast were studied by means of stomach content analysis. The samples were obtained on eight seasonal oceanographic cruises, carried out between October 1985 and July 1987. The importance of each food item was evaluated on the basis of the Index of Relative Importance and the feeding similarity by Percentage of Similarity. The results indicated that both species are benthic feeders, preying mainly on Crustacea, especially Amphipoda, Caridea and Brachyura. Teleostei were also important for R. agassizii. Seasonal variation of the diet seems to be associated with the availability of the prey, whose distribution and abundance are related to the dynamics of the water masses of the region. Juveniles and adults of P. extenta exploited the same resources while juveniles and adults of R. agassizii presented low diet similarity during most of the year. Caridea were an important food for all length classes of R. agassizii, while Amphipoda were for smaller specimens, and Teleostei for larger ones. The feeding overlap between the two species was higher during autumn 1986, winter 1986 and winter 1987.
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Palavras-chave
Rajidae, conteúdo estomacal, hábitos alimentares, Atlântico Sul, Brasil, Rajidae, stomach content, feeding habits, South Atlantic, Brazil
Como citar
Revista Brasileira de Biologia. Instituto Internacional de Ecologia, v. 61, n. 2, p. 217-238, 2001.