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Person
de Noronha Gamito Afonso dos Santos, Manuel Eduardo
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- Feeding behaviour of the bottlenose dolphin, Tursiops truncatus ( Montagu, 1821 ) in the Sado estuary, Portugal, and a review of its prey speciesPublication . Santos, Manuel Eduardo dos; Coniglione, Chiara; Louro, SóniaComportamento alimentar do golfinho-bico-de-garrafa, Tursiops truncatus ( Montagu, 1821 ) no estuário de Sado, Portugal e uma revisão de suas espécies de presas. O objetivo desse artigo é apresentar a informação disponível acerca do comportamento alimentar e da dieta dos golfinhos-bico-de-garrafa residentes no estuário de Sado, em Portugal. Os golfinhos-bico-de-garrafa são predadores oportunistas, com uma dieta diversificada que inclui crustáceos, cefalópodes e peixes pelágicos e bentônicos, de acordo com a disponibilidade e abundância. A observação direta dos comportamentos alimentares, apoiada por registros fotográficos e videofotográficos, permitiu a identificação de algumas das espécies de presas do golfinho desta região, nomeadamente a enguia-europeia, taínhas, o choco-comum e o polvo. Uma lista de espécies de presas mais comuns dos golfinhos-bico-de-garrafas em diversas regiões foi comparada com as espécies de peixes e cefalópodes que ocorrem no estuário do Sado. Esta comparação levou à uma elaboração de uma lista adicional de espécies que provavelmente também são presas dos golfinhos na região. A observação de comportamentos alimentares foi mais frequente nas partes mais rasas da área de estudo, onde deverá ser mais fácil encontrar e capturar presas.
- Sound production by the lusitanian toadfish Halobatrachus didactylusPublication . Santos, Manuel Eduardo dos; Modesto, Teresa; Matos, Ricardo Jorge S.C.; Grober, Matthew S.; Oliveira, Rui Filipe; Canário, Adelino V. M.Several batrachoidids have been known to produce sounds associated with courtship and agonistic interactions, and their repertoires have been studied acoustically and behaviourally. In contrast, sound production of the Lusitanian toadish Halobatrachus didactylus, although often noted, has not been acoustically studied. This sedentary predator of Northeastern Atlantic coastal waters is usually found in sandy and muddy substrates, under rocks or crevices. Sound recordings were made in Ria Formosa, a lagoon complex in southern Portugal. The sound producing apparatus was studied in adult individuals of both sexes captured by local fishermen. It is shown that this species produces acoustic emissions similar to other batrachoidids. It produces a long, rhythmical, tonal sound, often in choruses, which is comparable to the boatwhistle or hum signals of Opsanus and Porichthys, and a complex of signals that were classified as grunts, croaks, double croaks and mixed calls ('grunt-croak’). As in other toadfishes, H. didactylus presents sonic muscles connected to a bi-lobed swimbladder. Asynchronous contractions of the sonic muscles were detected when massaging the ventral surface of the fish.
- Influence zones of pile-drive noise on a resident population of bottlenose dolphins in the Sado estuary, PortugalPublication . Luís, Ana Rita; Silva, C.; Andrade, Fabiana Fontenelle de; Santos, Manuel Eduardo dosInexistente
- Whistles of bottlenose dolphins (Tursiops truncatus) in the Sado Estuary, Portugal: Characteristics, production rates, and long-term contour stabilityPublication . Santos, Manuel Eduardo dos; Louro, Sónia; Couchinho, Miguel Nogueira; Brito, Cristina MariaThis study focuses on the whistle characteristics and production patterns of bottlenose dolphins (Tursiops truncatus) resident in the Sado Estuary, Portugal. Recordings and observations were conducted inside the estuary and in adjacent coastal waters using single hydrophones between 1987 and 2000. In the groups sampled, the mean number of whistles emitted per minute per animal was 0.28. The acoustic characteristics of a sample of 735 whistles were measured and compared with data from other Tursiops populations, showing that, in a pattern of overall similarity, the whistles recorded in the Sado are relatively long and the frequency range used is relatively wide. Mean peak frequency was 9.2 kHz. About 30% of the whistles were stereotyped, and remarkable stability was found in several contours over a 12-year period. No relation was found between dolphin group size and whistle rate, suggesting some restriction in production; and no relation was found between dolphin group size and the emission of different contours. Significant variation was found between episodes of simple travel and more aroused activities in terms of the production of whistles in general and also of different whistle contours.