Can smaller benthic foraminifera be ignored in paleoenvironmental analyses?

Investigations of the distribution patterns have been carried out on various size fractions of faunal assemblages (eg, >63 mu m, >125 mu m, >150 mu m, >250 mu m and >300 mu m). In our study, information obtained from examination of the 63-125-mu m and the >125-mu m fractions is compared with published data based solely on the larger size fractions. We found that sieves with large openings (125 mu m, 150 mu m, 250 mu m, 300 mu m) allow a significant loss of specimens, including environmental index species, and may have created artificial 'barren zones' in sequences dominated by small-sized species. This suggests that inclusion of the 63-125-mu m fraction in foraminiferal studies may be well worth the additional time and effort required. Data from different sources certainly could be more readily compared or integrated if this procedure was more widely adopted in paleoceanographic studies. -Authors