Occurrence of hourglass dolphin (Lagenorhynchus cruciger) and habitat characteristics along the Patagonian Shelf and the Atlantic Ocean sector of the Southern Ocean

DELLABIANCA N; SCIOSCIA G; SCHIAVINI A; RAYA REY A

POLAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2012 p. 1921 - 1927

0722-4060

The hourglass dolphin, Lagenorhynchus cruciger,is one of the smallest cetaceans found in Antarcticwaters. Although frequently observed, this is one of theleast studied species of dolphin. In this study, we investigatethe occurrence of hourglass dolphin in the South-WestAtlantic and Southern Ocean from 42S to 63S andcharacterize the oceanographic and environmental featuresassociated with their occurrence. Sighting data were collectedduring two scientific cruises in December 2009 andJanuary and February 2011 and integrated into a geographicalinformation system with environmental variablessuch as sea surface temperature, ocean colour, depth, distanceto oceanographic fronts and distance from shore. Weused a principal component analysis (PCA) to identifypatterns in data and a non-hierarchic cluster analysis(K means) to classify observations into groups. A total of19 sightings (96 individuals) were recorded. Group sizeranged from one to twelve dolphins (mean 5.05). We coulddifferentiate two groups in relation to the environmentalconditions where animals were found, one group occurringin shallow coastal waters and the other occurring in deeperand colder waters further offshore. The present studycontributes novel information on environmental measuresassociated with hourglass dolphin distribution in the South-West Atlantic and Southern Oceans. Additionally, itincludes relatively high sighting clusters of this species intwo highly productive and biodiverse areas (BurdwoodBank/Isla de los Estados and the South Shetland Islands).