Habitat partitioning mediates the coexistence of sympatric dolphins in a tropical fjord-like embayment

Bottlenose dolphins (Tursiops truncatus) and pantropical spotted dolphins (Stenella attenuata) co-occur in Golfo Dulce, a fjord-like embayment located in the southern Pacific coast of Costa Rica. We evaluated if spatial overlap by these dolphin species is associated with similar environmental requir...

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Bibliographic Details
Published in:Journal of mammalogy 2018-06, Vol.99 (3), p.554-564
Main Authors: Oviedo, Lenin, Fernández, Marc, Herra-Miranda, David, Pacheco-Polanco, Juan Diego, Hernández-Camacho, Claudia J., Aurioles-Gamboa, David
Format: Article
Language:English
Subjects:
coexistence
Costa Rica
ecological niche modeling
Feature Articles
Golfo Dulce
habitat partitioning
spatial overlap
Stenella attenuata
sympatry
Tursiops truncatus
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Summary:Bottlenose dolphins (Tursiops truncatus) and pantropical spotted dolphins (Stenella attenuata) co-occur in Golfo Dulce, a fjord-like embayment located in the southern Pacific coast of Costa Rica. We evaluated if spatial overlap by these dolphin species is associated with similar environmental requirements. Presence-only models based on niche theory were constructed by contrasting a set of spatial locations with the responses of the target species to abiotic ecogeographical variables (EGVs: depth, slope, distance to rivers, distance to 200 m isobath, mean sea surface temperature, and variation in sea surface temperature). Models were cross-validated with levels of discrimination that ranged from acceptable to excellent based on the area under the curve assessment (T. truncatus, rainy season: 0.76, dry season: 0.83; S. attenuata, rainy season: 0.84, dry season: 0.89). Both dolphin species occur in Golfo Dulce year-round; the lack of seasonality documented previously was supported by the models. Species distribution models showed no spatial overlap, with differences in EGVs affecting their distribution (T. truncatus: distance to river + distance to 200 m isobath, S. attenuata: depth + sea surface temperature). We argue that the coexistence of both predators in Golfo Dulce is linked to habitat heterogeneity, where critical habitats are spatially differentiated. The lack of fine-scale spatial overlap, along with influential abiotic variables, highlights a process of coexistence for dolphins that are sympatric at the scale of Golfo Dulce, but within the Gulf there is fine-scale allopatry.
ISSN:0022-2372
1545-1542
DOI:10.1093/jmammal/gyy021