Silicoflagellates and Actiniscus : vertical fluxes at Pacific and Atlantic sediment trap stations

Vertical fluxes of silicoflagellate skeletons were measured in meso- and bathypelagic zones at four PARFLUX sediment trap stations located in the Pacific and Atlantic oceans. The average flux measured at several depths ranged from 35 X 103 skeletons/m2/day at the Pacific gyre (P1) station to 424 X 103 skeletons/m2/day at the Panama Basin (PB1) station. The skeletal fluxes at these stations constituted a few weight percent or less of the total biogenic opal flux. The fluxes measured at Station P1, as well as the relative abundance of different assemblages, were fairly constant with depth. At Station PB1, while relative abundance of assemblages was constant with depth, the flux measured at mesopelagic depths was threefold greater than that in the bathypelagic zone. At equatorial Atlantic Station E a slight increase toward the bathypelagic zone is correlated with gradual change in the relative abundance of two predominant taxa, suggesting seasonality in the production of each taxa. Aggregate forms of vertical settling were observed at Station E; the number of skeletons in the aggregates was more than one-half of the total number in the mesopelagic zone and it decreased with increasing depth. The percent abundances of Dictyocha messanensis messanensis and Distephanus pulchra are correlated with organic carbon flux at four stations. Preservation of the skeletons in Holocene sediment at Station P1 is less than one percent of the silicoflagellate flux

Radiolaria : flux, ecology, and taxonomy in the Pacific and Atlantic

Radiolarians setting through the oceanic water column were recovered from three stations (western tropical Atlantic, Station E; central tropical Pacific, Station P1; and Panama Basin, Station PB) using PARFLUX sediment traps in moored arrays at several depths. The taxonomic diversity of the radiolarian assemblages in the sediment traps was very high. A total of 420 taxa (including 23 new taxa) were found at the three stations; of these 208 taxa were found at Station E. The polycystine radiolarians generally reach the sea floor with little change in abundance or species composition, although slight skeletal dissolution occurs during their descent through the water column. The phaeodarian radiolarians, on the other hand, are largely dissolved within the water column; only a few species reach the sea-floor and these dissolve rapidly at the sediment-water interface. Most radiolarian skeletons sink as individuals through deep water columns without being incorporated into large biogenic aggregates. Because significant numbers of nassellarian and phaeodarian species are deep-water dwelling forms, the diversity of radiolarians increases with increasing depth in the mesopelagic zone. The vertical flux of the total radiolarians arriving at the trap depths (in x 103 individuals/m2/day) ranged from 16-24 at Station E, 0.6-17 at Station Pl, and 29-53 at Station PB. On the average 25% and 69% of the total radiolarian flux is transported by Spumellaria and Nassellaria, respectively, while 5% is carried by Phaeodaria. The supply of radiolarian silica (mg Si02/m2/day) to each trap depth ranged from 2.5-4.0 at Station E, 0.9-3.2 at Station Pl, and 5.7-10.4 at Station PB. The Radiolaria appear to be a significantly large portion of the Si02 flux in the > 63 μm size fraction and thus play an important role in the silica cycle. When the radiolarian fluxes at the three stations are compared with Holocene radiolarian accumulation rates in the same areas it became apparent that several percent or less of the fluxes are preserved in the sediment in all cases and the rest must be dissolved on the sea-floor

Seasonal fluxes of silicoflagellates and Actiniscus in the subarctic Pacific during 1982-1984

A seasonal flux study of silicoflagellates and Actiniscus was conducted at subarctic Pacific Station PAPA (50N, 145W; water depth 4200 m) during September, 1982 through August, 1984 using PARFLUX high resolution time series sediment traps deployed at 1000 m and 3800 m depths. The time series sediment trap samples were collected for 4 to 16-day periods depending on the samples; most of the samples were collected for 14 to 16-day periods. From a depth of 3800 m, a total of 47 samples represents a nearly two-year continuous record of the fluxes of silicoflagellate and Actiniscus taxa. An additional 12 samples from 1000 m represent a 6-month period, providing synchronized time series samples with the deeper depth which is essential to understand particle sinking processes.Seven silicoflagellate taxa, several variants of silicoflagellates, and Actiniscus pentasterias (Ehrenberg) group were examined. A total of more than 32 × 103 specimens were identified to species level and counted in this study. Distephanus speculum (Ehrenberg) and Dictyocha mandrai Ling are the dominant taxa, generally contributing \u3e75% of the flux assemblages. Considerable intra-annual and interannual flux variability was observed with the range of total silicoflagellate flux varying from 5 × 103 to 700 × 103 skeletons m−2day−1 during the two years. Seasonal flux patterns of D. speculum and its closely related taxa are internally consistent and they conform with the productivity signals shown by diatom, total mass, or opal fluxes. The seasonal flux pattern of D. mandrai exhibits its own unique late fall/early winter signals with most of the cumulative flux concentrated during this season in year 1.The sinking mechanism of silicoflagellates is large aggregates which sink faster than discrete specimens. Silicoflagellates generally sink faster than marine snow mediated diatom assemblages. The larger influence of fecal material may be responsible for the observed faster sinking speeds than those of diatoms. No significant dissolution of silicoflagellate assemblages occurs in the water column due to innate protection and to accelerated sinking. Most of the silicoflagellates supplied to the sea floor are subsequently dissolved, and only 1% of the total supply is preserved in the surface sediments, with considerably altered assemblages

A Correlation of Flooding Velocities in Countercurrent Gas-Liquid Contactor of Column Type

In this report, the analogies of the maximum allowable liquid and gas velocities in various countercurrent gas-liquid contactors of column type are considered analytically. That is, by plotting the flooding points of various columns in a gas-liquid separated coordinates, the similar curves have been obtained in each column. Because the difference of these curves is due to the shape of each column, the difference of each shape must be corrected and evaluated as a ahape factor. Then, by containing this factor in coordinate variables, various flooding points in each column may be correlated by a single curve. If this correlation curve is used, the flooding velocity can be estimated easily, and the maximum allowable liquid and gas velocities in these countercurrent contactors of column type can be compared

Interannual variability of siliceous phytoplankton fluxes and relationships with hydrography in the northeastern subarctic Pacific, 1982-1986 [abstract and figures]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Time-series flux variabilities of biogenic opal particles were measured during 1982-1986 at pelagic Station PAPA (50° N, 145° W) located just south of the Gulf of Alaska, eastern North Pacific. PARFLUX sediment traps with two week sampling increments were deployed at 1000 m and 3800 m in 4200 m deep water, yielding nearly continuous time-series flux records for four years. The flux data allowed us to examine interannual and seasonal variabilities of siliceous phytoplankton production as well as environmental signals retained within the siliceous shells, which can be used to reconstruct environments