Fine scale distribution constrains cadmium accumulation rates in two geographical groups of Franciscana dolphin from Argentina

POLIZZI, P; DENUNCIO, P; CHIODI BOUDET, L; RODRÍGUEZ, D; GERPE, M

MARINE POLLUTION BULLETIN

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2013 vol. 72 p. 41 - 46

0025-326X

Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified as Vulnerable A3d by the International Union for Conservation of Nature. Cadmium accumulation was assessed in two geographic groups from Argentina; one inhabits the La Plata River estuary, an area with recognized high anthropogenic impact, and the other is distributed in marine coastal areas with negligible pollution. Despite a more pristine environment, marine dolphins showed higher tissue concentrations. The accumulation was evident from the first year of life, with the trophic independence. The Annual Accumulation Rates (AAR) in kidney were highest in the age periods between 2 and 5 years. These results are closely associated with dietary Argentine anchovy (Engraulis anchoita), which was absent in the diet of estuarine dolphins. Cluster analysis also showed high levels of association with the presence of anchovy. Accordingly, estuarine dolphins showed an increase of accumulation only after 6 years of age. The AARs were higher only in the older dolphins, although the values did not achieve those observed in marine dolphins. Hence, dietary anchovy is the likely vector of Cd in the marine food chain in shelf waters of Argentina. The difference in the fine scale distribution of species influences dietary exposure to Cd and, along with other data, indicates two stocks in Argentina.