About 150 radiolarian taxa were encountered during this study (Table T1). These taxa include some undescribed or unfamiliar forms, particularly within the families Actinommidae, Spongodiscidae, Pyloniidae, Litheliidae, and Plagoniidae. Many of these are not differentiated below the level of family or subfamily.
Generally, radiolarians are common to abundant and moderate to well preserved in the upper to middle portion (0 to ~380 mbsf) of Hole 1082A. Abundance and preservation of radiolarians decline in Sample 175-1082A-5H-4, 46-48 cm (41.26 mbsf). Similar reductions occur in short intervals at 20.05-29.93 mbsf in Hole 1081A, at 41.68 mbsf in Hole 1084A, and at 18.17 mbsf in Hole 1087A, where many species disappear temporarily (Wefer, Berger, Richter, et al, 1998). These changes may reflect a short-spanned oceanic event extending over the Benguela Current region, that possibly resulted in decline of productivity of radiolarians.
In the lower portion (below ~380 mbsf) of Hole 1082A, radiolarians are rare to abundant and absent in some horizons, and their preservation is poor to moderate. Radiolarian specimens from this interval often show dissolution signals because they were corroded and sometimes highly fragmented. Sample 175-1082A-63X-4, 46-48 cm (586.26 mbsf), is very poor in radiolarian abundance and preservation, so counting was not done for this sample.
Radiolarian assemblages are dominated by temperate- to cool-water species represented by the Actinomma boreale group, Larcopyle buetschlii, Lithelius minor, and Cycladophora davisiana through the upper to middle portion of Hole 1082A (above ~380 mbsf). This indicates the predominance of a temperate to cool oceanic climate through the equivalent time interval, similar to today's conditions under the cool Benguela Current. Temperate species L. minor is one of the dominant radiolarian elements in the lower middle to lower portion (below ~390 mbsf). Some Antarctic forms, Cycladophora pliocenica and Antarctissa species, occur in low abundance in the middle part of the sequence (193.47-364.86 mbsf), suggesting minor invasions of antarctic/subantarctic waters. Warm-water species, including collosphaerid species, Didymocyrtis tetrathalamus, and Octopyle stenozona/Tetrapyle octacantha, occur in low abundance consistently through the hole, indicating less influence of warm-water currents into the Walvis Basin.