MEPS 421:217-227 (2011)  -  doi:10.3354/meps08912

Modeling habitat use for dusky dolphin and Commerson’s dolphin in Patagonia

Griselda V. Garaffo1,*, Silvana L. Dans2,3, Susana N. Pedraza2,3, Mariana Degrati2,3,  Adrián Schiavini4,5, Raúl González6, Enrique A. Crespo2,3

1Universidad Nacional de Mar del Plata, Funes 3600, CP (7600) Mar del Plata, Argentina
2Centro Nacional Patagónico (CONICET), Boulevard Almirante Brown 2825, CP (9120) Puerto Madryn, Chubut, Argentina
3Universidad Nacional de la Patagonia, Boulevard Almirante Brown 3600, CP (9120) Puerto Madryn, Chubut, Argentina
4Centro Austral de Investigaciones científicas (CONICET), Houssay 200, CP (V9410) Ushuaia, Tierra del Fuego, Antártica e Islas del Atlántico Sur, Argentina
5Wildlife Conservation Society Representación, Amenabar 1595, Buenos Aires, Argentina
6Instituto de Biología Marina y Pesquera Almirante Storni, Güemes 1030, CP (8520) San Antonio Oeste, Río Negro, Argentina

ABSTRACT: Several species of small cetaceans inhabit the coastal area of Patagonia (Argentina), but little is known about their distribution and the degree of overlap between them. The goal of the present study was to build habitat-selection models for small cetaceans in order to assess areas of particular importance for the different species. These models were constructed using physiographic and remotely sensed variables. From 1994 to 2007, 13 aerial surveys were conducted along the Patagonian coast (from Golfo San Matías: 40°40’–42°14’S, 65°00’–63°47’W to Bahía de los Nodales: 48°00’S, 65°35’W). A grid of 0.5° × 0.5° cells was constructed for the study area. Each cell was characterized by environmental variables and by the encounter rate (ER) for each cetacean species. The ER of each species was investigated in relation to environmental variables using generalized linear models, and model averaging (multimodel inference) was used to obtain a predicted ER for the different species. The correlation between the ER of different species was analyzed by Spearman rank correlation. The environmental variables that were found to be significant predictors of species distribution differed between species. The ERs of dusky dolphin Lagenorhynchus obscurus and Peale’s dolphin L. australis showed a positive relationship. Commerson’s dolphin Cephalorhynchus commersonii presented a more coastal distribution than the other species, and individuals were more often found feeding in estuarine zones. Knowledge of the patterns of distribution of small cetaceans along the Patagonian coast provides baseline knowledge of how these species interact with each other and their environment. Such information should be considered when managing potential areas of conflict between coastal small cetaceans and human activities.

KEY WORDS: Distribution modeling · Dolphins · Generalized linear model · Habitat selection · Patagonia

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Cite this article as: Garaffo GV, Dans SL, Pedraza SN, Degrati M, Schiavini A, González R, Crespo EA (2011) Modeling habitat use for dusky dolphin and Commerson’s dolphin in Patagonia. Mar Ecol Prog Ser 421:217-227

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