Detailed fluxes of radiolarian biocoenosis including 420 species have been measured by PARFLUX sediment trap experiments in the Sargasso Sea (Station S), western tropical Atlantic (E), central tropical Pacific (P₁), and Panama basin (PB). The samples were collected at 3 to 5 trap depths in the mesopelagic and bathypelagic zones during 2 to 4 month deployments. The measured fluxes of total Radiolaria in the unit of × 10⁵shells/ cm²/10³ yr at each station were: (E) 5.83 to 8.66; (P₁) 0.21 to 6.22; and (PB) 10.72 to 19.40. In all cases, the suborder Nassellaria represented the most contributions in number of shells (60 to 73%), followed by Spumellaria (18 to 36%). Paeodaria, a soluble end member, represented 1 to 8% in the flux of the shell number, although it contributed up to 23% in SiO₂ mass fluxes owing to the large shell size. Comparisons of these fluxes with the Holocene accumulation rates yielded the percentage of preservation of total (Radiolaria: (S) 0%, (E) 0.8%, (P₁) 0.004%, and (PB) 9.3%. The extent of preservation appears to be proportional to the

End_Page 556------------------------------

extent of fluxes to the sea floor (see figure). Differential preservation of the species is evidently taking place. For example, Spumellaria, a solution resistant end member, represents 29.2% preservation, whereas Nassellaria and Phaeodaria represent 2.8% and 0%, respectively, in the core tops from the Panama

Figure

basin. Clearly, thanatocoenosis in the Holocene sediments is drastically different from the living counterparts in the overlain water column. Major dissolution depth of spumellarian and nassellarian shells is at the sea floor. Phaeodarian shells dissolve in the water column as well as at the sea floor.

End_of_Article - Last_Page 557------------