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Mobilization of persistent organic pollutants in blubber of humpback whales (Megaptera novaeangliae) sampled in the feeding areas (Southern Ocean and southern Chilean Coast) and during migration to breeding and calving grounds off the coast of Brazil

Grant number: 20/15305-5
Support type:Regular Research Grants
Duration: August 01, 2021 - July 31, 2023
Field of knowledge:Physical Sciences and Mathematics - Oceanography - Chemical Oceanography
Principal researcher:Rafael Andre Lourenço
Grantee:Rafael Andre Lourenço
Home Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Assoc. researchers: EDUARDO RESENDE SECCHI ; João Carlos Gomes Borges ; Luciano Dalla Rosa ; Márcia Caruso Bícego ; Paula Baldassin ; Rosalinda Carmela Montone ; Salvatore Siciliano ; Satie Taniguchi

Abstract

Humpback whales (Megaptera novaeangliae) in the southern western hemisphere are the mammals that travel the longest distances to mate and reproduce in South America and the Caribbean, after feeding in the Southern Ocean and the southern coast of Chile. The breeding and calving grounds are in the northeast of Brazil (classified as stock A) and on the coasts of Peru, Ecuador, Colombia and Panama, (called stock G). The energy expenditure for this displacement is enormous, since the humpbacks are fasting from the migration area until their returns. It is estimated that there is a loss of approximately 20-40% of its blubber layer due to this movement. In order to evaluate these changes, analyzes of persistent organic pollutants (POPs), such as organochlorine pesticides and polychlorinated biphenyls and their mobilization in the adipose layer will be carried out. Those ubiquitous contaminants have been reported in Antarctic humpback whales, but with little information on the South American coast both in the Atlantic and the Pacific Oceans. Analyzes of fatty acids in the superficial blubber layer from stranded whales will be applied in available samples from each location since there may be different profiles of these compounds during the period of spending energy and its recovery. The isotopic ratio of carbon (´13C) and nitrogen (´15N) will be done only in animals that have skin (biopsy) or liver, in the case of stranded whales, and it will help the interpretation of the behavior and feeding of these animals. Samples collection in Antarctica (n = 46), Chile (n = 22) and Brazil (n = 41) has already been carried out by partner institutions. Groups that work with cetaceans in Brazil have already agreed to supply the tissues to be collected in the future. Samples of adipose tissue from other whale species will be collected opportunistically to compare these profiles, since the behavior is inherent to each species. The organic compounds will be extracted with dichloromethane and n-hexane. The fatty acids will be analyzed after esterification with sulfuric acid and methanol while the POP extract will be cleaned up in an adsorption chromatographic column followed by the column with gel permeation. The identification and quantification will be done by gas chromatography with mass spectrometry with a single quadrupole (GC/MS) for fatty acids and with the triple quadrupole (GC/MS/MS) for POPs. The study of the organic compounds present in the blubber of humpback whales during the long journey between the foraging and mating areas will be extremely valuable to better understand how is the adaptation of this highly migratory species happens under conditions in which huge changes in their energy sources occur. (AU)

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