Distribution and habitat characteristics of dolphins of the genus Stenella (Cetacea: Delphinidae) in the southwest Atlantic Ocean

Abstract

The distribution of dolphins of the genus Stenella is poorly known in the southwest Atlantic Ocean. A complete review of records (n = 311) of these dolphin species was performed to describe distribution and habitat. Atlantic spotted dolphins S. frontalis occur in both southern (21 to 33°S) and northern Brazil (north of 06°S), with a hiatus in its distribution off eastern South America. This species presents the highest preference for nearshore habitats, restricted to waters within the 1000 m isobath. Pantropical spotted dolphins S. attenuata are found in tropical waters as far south as 22°S and are mainly observed off northeastern South America. They occur beyond the continental shelf break in depths > 850 m. Clymene dolphins S. clymene are distributed in deep waters (1390 to 4500 m) as far south as 30°S. Strandings are more common where the continental shelf is narrower. Spinner dolphins S. longirostris are found in oceanic waters as far south as 30°S. They inhabit tropical waters over the shelf and slope (depths ranging from 170 to 2700 m). The striped dolphin S. coeruleoalba is the least known species of the genus in the western South Atlantic. Most records are from temperate waters in southern Brazil and Argentina. The distributions of S. attenuata, S. clymene and S. longirostris overlap to a great extent and are predominantly oceanic and associated with warm ocean currents. S. frontalis seems to prefer a different, coastal habitat, influenced both by warm currents and upwelling areas. The discontinuous distribution of this species suggests that an isolated population inhabits the southern coast of Brazil.

Cetacean records along São Paulo state coast, Southeastern Brazil

“…With the discovery of a main breeding area off southern Brazil (~27 o S) (OTT et al, 2008), the recovery of the right whale population from past exploitation may be expanding the breeding area to include protected bays in southeastern Brazil. The northern coast of SP state has shallow protected bays which have been used by female-calf pairs during the last 20 years (see LODI et al, 1996;SANTOS et al, 2001a (see ZERBINI et al, 2004;MORENO et al, 2005;TAVARES et al, 2010), as well as for the higher incidence of these species' strandings. A few records have related to strays from their currently known range -such as B. arnuxii, M. europaeus and L. peronii.…”

“…The body showed clear evidences of trauma provoked by collision with a boat. • Stenella frontalis (G. Cuvier, 1829): Atlantic spotted dolphins are commonly observed from 21 o S to 33 o S (ZERBINI et al, 2004;MORENO et al, 2005). Strandings are common in SP throughout the year and all along the coast, rendering a considerable amount of osteological material deposited mainly in the MZUSP, the MIPS, the PA and the SOSMM collections.…”

Review of thirty-two years of toothed whale strandings in Santa Catarina, southern Brazil (Cetacea: Odontoceti)

“…The high influence of the Subtropical Confluence and its mixing of waters along the coast of Santa Catarina state (gordon 1989) would be a strong reason for the occurrence of these species within this region. Spotted dolphins are common throughout the south and southeast of Brazil, with confirmed sightings along the continental shelf mainly between 20.5°S and 30°S (Moreno et al 2005, do aMaral et al 2015.…”

“…Some of these are oceanic and rarely seen near the coast (e.g., L. hosei, G. griseus, S. coeruleoalba, Clymene dolphin, Stenella clymene (Gray, 1850), which explains their low record numbers. Stenella clymene and S. coeruleoalba have been observed in rare occasions on the continental shelf of Southern Brazil and Argentina (Moreno et al 2005, do aMaral et al 2015.…”

Trace elements in different species of cetacean from Rio de Janeiro coast

“…Individuals of S. frontalis were sighted in depths ranging from the upper continental shelf (20 m) to the slope area (961 m). 44 In this study, concentrations of essential and nonessential elements found in the liver of cetaceans species were of the same order of magnitude as those reported in previous studies with the same species from the South American coast (Table 4), but hepatic copper concentration in the three cetaceans species (S. guianensis, P. blainvillei and S. frontalis) from the southeastern Brazilian coast, was lower than those found in samples from the southern coast of Brazil 10 (Table 4) and Argentine coast 32,34 (Table 4). Cadmium concentrations in the liver of P. blainvillei from the coastal areas of Argentina 32,34 (Table 4) and S. frontalis from the Brazilian southern coast 7 (Table 4) presented higher concentrations than those found in the liver of these dolphin species from the northern coast of Rio de Janeiro (Brazil).…”