LUCIFORA et al.: South Atlantic distribution of Cetorhinus maximus 1 UNCORRECTED PROOF Estimating the geographic range of a threatened shark in a data- poor region: Cetorhinus maximus in the South Atlantic Ocean

• Main Authors: Luis O. Lucifora, Santiago A. Barbini, Edgardo E. Di Giácomo, Juan A, Daniel E. Figueroa
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Cetorhinus maximus; North Atlantic; South Atlantic Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.649.9021; http://www.currentzoology.org/site_media/onlinefirst/downloadable_file/2014/11/21/Lucifora.pdf

Abstract The distribution of the planktivorous basking shark, Cetorhinus maximus, is influenced by zooplankton abundance at small scales and temperature at medium scales in the North Atlantic. Here, we estimate the distribution of basking sharks on South Atlantic continental shelves, and the relative importance of chlorophyll concentration, as a proxy for zooplankton abundance, and temperature in determining habitat suitability for basking sharks at large scales. We used maximum entropy (MaxEnt) and maximum likelihood (MaxLike) species distribution modelling to test three hypotheses: the distribution of basking sharks is determined by (1) temperature, (2) chlorophyll concentration, or (3) both chlorophyll and temperature, while considering other factors, such as oxygen and salinity. Off South America, basking shark habitat included subtropical, temperate and cool-temperate waters between approximately 20oS and 55oS. Off Africa, basking shark habitat was limited to cool-temperate waters off Namibia and southern South Africa. MaxLike models had a better fit than MaxEnt models. The best model included minimum chlorophyll concentration, dissolved oxygen concentration, and sea surface temperature range, supporting hypothesis 3. However, of all variables included in the best model, minimum chlorophyll concentration had the highest influence