The influence of seasonality, tide and time of activities on the behavior of Sotalia guianensis (Van Bénéden) (Cetacea, Delphinidae) in Pernambuco, Brazil

Abstract

Data on Sotalia guianensis Van Bénéden, 1864 occurrence on the beaches of Pernambuco (Northeastern Brazil) is restricted to information on stranding and on printed material from local newspapers; actual observations of such animals have not been published. This study intends to determine the use of habitat, behavioral activities and assess the relationships between environmental factors and the recorded behavior. Observations were conducted on open sea coastal areas, on the beaches of Olinda and Piedade, as well as in sheltered areas, in the ports of Recife and Suape. Monitoring was carried out every month in each area, during two consecutive days, from September 2004 to August 2005. Results corroborate that this species prefers to occupy more protected environments, the port of Recife being the main concentration area for such species. Piedade is just an exploratory area, possibly due to shark occurrence. Olinda is only occasionally used. Concentration areas seem to be used for feeding, and incidence of caudal exhibition suggests that most of the estuarine dolphin prey items are demersal. Environmental conditions (seasonality, tide and time) did not show to be significant when related to the estuarine dolphin behavior.

Spatial distribution and activities of the estuarine dolphin Sotalia guianensis (van Bénédén, 1864) (Cetacea, Delphinidae) in Pontal Bay, Ilhéus, Bahia, Brazil

“…The author suggests an opportunistic exploration of the direction and speed of the tide by estuarine dolphins to forage, enter and leave estuaries. Araújo et al (2007) found no significant differences between the relative frequencies of foraging events during flood and ebb tides in four port areas of Pernambuco. At Pontal Bay, the displacement direction of most individuals follows the tidal movement: an increased proportion of individuals move toward the back of the bay during the flood, and this proportion decreases during the ebb tide.…”

“…Hayes (1999) recorded a higher frequency of individuals in March at Iracema Beach in Ceará and related this abundance to heavy rainfall and the large amounts of fish present in the shallow waters of the area. In Pernambuco, Araújo et al (2007) observed a decrease in the number of individuals sighted with an increase in monthly precipitation. However, the frequency of sightings of estuarine dolphins was not related to precipitation intensity at Pontal Bay (Santos 2007).…”

Tidal and seasonal influences in dolphin habitat use in a southern Brazilian estuary

“…Guiana dolphins seem to exhibit strong site fidelity, and tend not to move very far from population habitat areas (Wedekin et al 2007, Hardt et al 2010. In open coastal environments, Araújo et al (2007) found no significant effects of tidal cycles on area utilization or variation in behaviour of the Guiana dolphin, while Azevedo et al (2007) did find tidal effects in an estuarine environment.…”

Reproductive morphology of female Guiana dolphins (Sotalia guianensis)

“…Other studies evaluated sexual maturity by growth, measuring and weighing the gonads (Santos et al 2001, Rosas and Monteiro-Filho 2002, Da Silva et al 2007, Araújo et al 2007, Katsumata 2010, Perrin and Reilly 1984, Pomeroy 2011. However, studies reporting the microscopic anatomy of the female genital organs are scarce.…”