Postnatal development of franciscana's (Pontoporia blainvillei) biosonar relevant structures with potential implications for function, life history, and bycatch. Issue 3 (2nd April 2015)

• Record Type: Journal Article
• Authors: Frainer, Guilherme; Huggenberger, Stefan; Moreno, Ignacio Benites
• Is Part Of: Marine mammal science. Volume 31:Issue 3(2015)
• Page Start: 1193
• Page End: 1212
• Publication Date: 2015-04-02
• Subjects: Marine mammals -- Congresses; Marine mammals -- Periodicals; Marine mammals, Fossil -- Periodicals; Mammifères marins -- Périodiques; 599.5
• DOI: 10.1111/mms.12211
• Languages: English
• ISSNs: 0824-0469

Abstract

<abstract abstract-type="main" id="mms12211-abs-0001"> <title>Abstract</title> <p>Franciscana dolphins (<italic>Pontoporia blainvillei</italic>) are the most endangered species of the western South Atlantic Ocean. The major cause of their vulnerability is incidental bycatch in fishery gill nets. Ontogenetic changes of biosonar relevant structures in <italic>Pontoporia</italic> were analyzed in five specimens (one female neonate, two male neonates and two male adults) using digital imaging technology (MRI, CT) and macroscopic dissections to compare structures involved in sound production and reception. These data were compared to an ontogenetic series of 69 macerated skulls of <italic>Pontoporia</italic> in order to elucidate the correlation between soft tissue structures and bones of the epicranial complex and to describe the development‐related changes in the mandible. Postnatal developmental shape changes of the posterior part of the right vestibular air sac followed bone formation and the melon with its right branch elongated, paralleling the flatter facial depression of adults. Minor postnatal developmental modifications were verified in the tympano‐periotic complex but a shape change of the mandible was visible by a ventral deviation of the posterior part of the mandible in adults. These results reveal postnatal changes in allometry and shape of biosonar relevant structures that may be one of the causes that increase bycatch of neonate and young <italic>Pontoporia</italic> individuals.</p> </abstract>