Wilton Aguiar Carvalho Silva Filho, Universidade Federal do Rio Grande, Rio Grande-RS, Brazil, Luciana Prado, Universidade de Brasilia, Instituto de Geociências, Brasilia, Brazil, Ilana C Wainer, Univ of Sao Paulo, Sao Paulo, Brazil, Zhengyu Liu, The Ohio State University, Columbus, OH, United States and Mauricio M Mata, Federal University of Rio Grande, Instituto de Oceanografia, Rio Grande, Brazil