Raw samples were placed in 100-mL beakers to which 10 mL of distilled water and 10 mL of 30% hydrogen peroxide were added; more was added if it strongly effervesced. After 1–3 hr, HCl was added until the fizzing subsided and the beaker was heated for 15 min. Samples were then left overnight and were centrifuged and decanted three times and washed out before strewn slides were made. Slides were prepared by resuspending the contents and quickly using a disposable pipette, dropping 2–3 drops onto a 22 mm x 50 mm coverslip. The pipette end was used to spread the drops over the surface of the coverslip. The coverslip was then placed on a hot plate at medium heat to dry. A small amount of balsam was put on the slide, and the coverslip was turned over and placed on the balsam. The slide was heated on the hot plate until the balsam spread over the area of the coverslip and the bubbling within the balsam subsided.
All slides were completely examined, with all specimens representing more than one-half of a silicoflagellate included in the counts. The distribution is shown in Table T1 for 150 samples with an interval of one sample per section.
This study was done at the Micropaleontology Undergraduate Research Laboratory at the University of Maine at Presque Isle (USA). The microscope work and some of the analyses were conducted by undergraduate students who have limited experience with silicoflagellates. Participating students generally have a year of training in micropaleontology and deep-ocean drilling and then conduct micropaleontology research as a directed independent project that is closely supervised by the laboratory's director (K. McCartney). The first author of this paper (R. Engel) has previously co-authored a silicoflagellate study for Leg 183 (McCartney et al., 2003).