Feeding associations between Guiana dolphins, Sotalia guianensis (Van Bénèden, 1864) and seabirds in the Lagamar estuary, Brazil
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Data
2010-02-01
Autores
Santos, M. C. O. [UNESP]
Oshima, J. E. F. [UNESP]
Pacífico, E. S. [UNESP]
Silva, E. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Internacional de Ecologia
Resumo
O objetivo principal do presente estudo foi de descrever as características a respeito das associações de alimentação entre o boto-cinza, Sotalia guianensis, e aves marinhas em duas áreas distintas do estuário do Lagamar, Brasil. Investigações efetuadas a partir de embarcação e direcionadas a estudos de foto-identificação de S. guianensis foram conduzidas no Estuário de Cananéia (EC) (25° 01' S e 47° 55' O) entre julho de 2004 e março de 2008, bem como no Complexo Estuarino de Paranaguá (CEP) (25° 24' S e 48° 24' O) entre abril de 2006 e fevereiro de 2008. em todas as ocasiões em que aves marinhas foram observadas em associações de alimentação multiespecífica com S. guianensis, dados sobre as espécies envolvidas e seus números foram obtidos. Dos 435 grupos de S. guianensis observados no EC, 38 (8,7%) envolveram interações com aves marinhas. No CEP, dos 286 grupos observados, 32 (11,2%) envolveram as interações mencionadas. As seguintes aves marinhas foram observadas em associações de alimentação com S. guianensis: Fregata magnificens, Sula leucogaster, Phalacrocorax brasilianus, Sterna sp. No EC, S. leucogaster foi significativamente mais observada em associação de alimentação com o boto-cinza (χ2 = 22,84; g.l. = 3 p < 0,05), enquanto no CEP não foram observadas diferenças quando comparadas as aves marinhas (χ2 = 5,78; g.l. = 3, p = 0,1223). No EC, associações de alimentação foram significativamente mais freqüentes em águas internas (χ2 = 9,52; g.l. = 2, p < 0,05) e no inverno (χ2 = 12,46; g.l. = 1, p < 0,05). Dentre estes eventos, 44,7% dos grupos de associação foram compostos por mais de uma espécie. Sazonalidade nas associações de alimentação também foi observada no CEP (χ2 = 4,76; g.l. = 1, p < 0,05), com os mesmos padrões observados para o EC. As interações foram mais freqüentes na baía das Laranjeiras, CEP (χ2 = 11,65; d.f. = 2, p < 0,05). Dentre estes eventos, 74,2% dos grupos de associação foram compostos por mais de uma espécie de ave marinha. A transparência da água, a distribuição e a abundância de presas e das aves marinhas, o tamanho de grupo dos cetáceos, e o ciclo de vida das aves marinhas e das presas são listados como os principais fatores que favorecem as associações de alimentação multiespecífica no estuário do Lagamar.
The main objective of the present study was to describe the characteristics regarding interactions between Guiana dolphins, Sotalia guianensis and seabirds in feeding associations in two distinct areas of the Lagamar estuary, Brazil. Boat-based surveys directed towards photo-identification studies of S. guianensis were conducted in the Cananéia Estuary (CE) (25° 01' S and 47° 55' W) from July 2004 to March 2008, as well as in the Paranaguá Estuarine Complex (PEC) (25° 24' S and 48° 24' W) from April 2006 to February 2008. on all occasions when seabirds were observed engaging in multi-species feeding associations with S. guianensis, data on species involved and their numbers were gathered. From 435 observed groups of S. guianensis in the CE, 38 (8.7%) involved interactions with seabirds. In the PEC, from the 286 observed groups, 32 (11.2%) involved the mentioned interactions. The following seabirds were observed in feeding associations with S. guianensis: Fregata magnificens, Sula leucogaster, Phalacrocorax brasilianus, and Sterna sp. In the CE, S. leucogaster was more commonly observed in feeding associations with Guiana dolphins (χ2 = 22.84; d.f. = 3, p < 0.05), while in the PEC no differences were reported when comparing seabird species (χ2 = 5.78; d.f.=3, p = 0.1223). In the CE, feeding associations were significantly more frequent in inner waters (subset A0; χ2 = 9.52; d.f. = 2, p < 0.05), and in winter (χ2 = 12.46; d.f. = 1, p < 0.05). Within these events, 44.7% of the association groups were composed by more than one seabird species. Seasonality in feeding associations was also observed in the PEC (χ2 = 4.76; d.f. = 1, p < 0.05), with same patterns observed in the CE. Interactions were more frequent in inner waters of the Laranjeiras bay, PEC (χ2 = 11.65; d.f. = 2, p < 0.05). Within these events, 74.2% of the association groups were composed by more than one seabird species. Water transparency, prey and seabird abundance and distribution, cetacean group size, and the life cycle of prey and seabirds are listed as the main factors addressing multi-species feeding associations in the Lagamar estuary.
The main objective of the present study was to describe the characteristics regarding interactions between Guiana dolphins, Sotalia guianensis and seabirds in feeding associations in two distinct areas of the Lagamar estuary, Brazil. Boat-based surveys directed towards photo-identification studies of S. guianensis were conducted in the Cananéia Estuary (CE) (25° 01' S and 47° 55' W) from July 2004 to March 2008, as well as in the Paranaguá Estuarine Complex (PEC) (25° 24' S and 48° 24' W) from April 2006 to February 2008. on all occasions when seabirds were observed engaging in multi-species feeding associations with S. guianensis, data on species involved and their numbers were gathered. From 435 observed groups of S. guianensis in the CE, 38 (8.7%) involved interactions with seabirds. In the PEC, from the 286 observed groups, 32 (11.2%) involved the mentioned interactions. The following seabirds were observed in feeding associations with S. guianensis: Fregata magnificens, Sula leucogaster, Phalacrocorax brasilianus, and Sterna sp. In the CE, S. leucogaster was more commonly observed in feeding associations with Guiana dolphins (χ2 = 22.84; d.f. = 3, p < 0.05), while in the PEC no differences were reported when comparing seabird species (χ2 = 5.78; d.f.=3, p = 0.1223). In the CE, feeding associations were significantly more frequent in inner waters (subset A0; χ2 = 9.52; d.f. = 2, p < 0.05), and in winter (χ2 = 12.46; d.f. = 1, p < 0.05). Within these events, 44.7% of the association groups were composed by more than one seabird species. Seasonality in feeding associations was also observed in the PEC (χ2 = 4.76; d.f. = 1, p < 0.05), with same patterns observed in the CE. Interactions were more frequent in inner waters of the Laranjeiras bay, PEC (χ2 = 11.65; d.f. = 2, p < 0.05). Within these events, 74.2% of the association groups were composed by more than one seabird species. Water transparency, prey and seabird abundance and distribution, cetacean group size, and the life cycle of prey and seabirds are listed as the main factors addressing multi-species feeding associations in the Lagamar estuary.
Descrição
Palavras-chave
Cetacea, associações de alimentação, Sotalia guianensis, aves marinhas, interações multi-específicas, Cetacea, feeding associations, Sotalia guianensis, seabirds, multi-species interactions
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 70, n. 1, p. 9-17, 2010.