Latitudinal and temporal planktonic foraminifera morphometric variation analysis through Brazilian continental margin

Abstract

Most of paleoclimatic interpretations are based on an artificial concept of specie, the morphospecies; they were classified basically on morphologic characteristics. Recently lots of species havd their genetic code described and it is recongnized that the classical morphospecies used nowadays are in fact composed by cryptic species and some of them display morphological intraspecific variations, the morphotypes. Both cryptic species and morphotypes can display different ecological preferences. Therefore, paleoclimatologic interpretations based on the paleontological concept of species, the morphospecies, are in fact a pool of distinct ecologic signals with intrinsic noise. In some cases, planktonic foraminifera morphotypes are already analyzed separately in some geochemichal analysis, which is the case for Globigerinoides ruber and Neogloboquadrina pachyderma. Nevertheless, most of morphospecies are still used as real species in paleoceanographic studies, resulting in low acuracy interpretations with high noise level. The main objective of the present study is to identify cryptic species/morphotypes in sediments from Brazilian continental margin both latitudinally and temporally, using core top and piston core samples. The results of this analysis will be compared with extant climatic register based on classical morphospecies analysis and oxygen isotope ratios. (AU)