Digital Books

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This collection is an assortment of manuals and texts reproduced by the MBLWHOI Library with permission of the copyright owners.

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Browsing Digital Books by Author "Honjo, Susumu"
  • Book
    Calcareous nannoplankton biocoenosis : sediment trap studies in the equatorial Atlantic, central Pacific, and Panama Basin
    (Woods Hole Oceanographic Institution, 1991) Steinmetz, John C. ; Honjo, Susumu
    Sediment traps deployed on three moored vertical arrays collected particles at various depths in the equatorial Atlantic (Station E), central Pacific (Station P1), and in the Panama Basin (Station PB1). The calcareous nannoplankton from the <63 μm size fraction were studied in order to characterize the flux of coccospheres and coccoliths, the taxa present, and their condition of preservation throughout the water column. The average calculated flux of coccospheres ranged from a low value of 24 coccospheres/m2/day in the central Pacific, to an intermediate value of 4725 in the equatorial Atlantic, to a high of 8030 in the Panama Basin. In general, the coccosphere flux decreased with depth at all three sites. Coccolith fluxes and flux profiles were significantly different at each of the three sites. At Station E, the flux decreased regularly with depth but increased sharply at the lowermost trap (724 m above the bottom). The average flux for the entire column was 316 x 106 coccoliths/m2/day. At Station P1, the flux was low in the shallowest two traps and increased markedly in the three deepest traps. This increase is due mainly to a suspected Umbilcosphaera sibogae bloom which occurred shortly before the traps were deployed in September 1978. The highest coccolith flux was recorded in the Station PB1 traps averaging 910 x 10 6 coccoliths/m2/day. The flux profile at this station was essentially constant in the shallowest four traps and decreased almost 59% in the lowermost two traps. The average coccolith carbonate fluxes for the entire columns for the Stations E, P1, and PB1 are, respectively, 2.53, 2.68, and 7.28 mg/m2/day. These fluxes represent minimum values, since coccospheres and coccoliths were also contained in fecal pellets and other particles larger than the size fraction studied (<63 μm). Scanning electron microscopic examination of the trap samples revealed 56 species belonging to 33 genera of calcareous nannoplankton. Three new species are described and illustrated: Alsphaera spatula n. sp., Umbilcosphaera calvata n. sp., ari;d Umbilcosphaera scituloma n. sp. A census of taxa present, including their relative frequency and state of preservation, is presented together with a photographic atlas of the taxa. Station E is the most diverse with 50 species, and is the best preserved of the three sites. Station PBi the least diverse with 26 more poorly preserved species. In general, the best preserved specimens were observed in the shallowest sample at each of the three sites; diversity and state of preservation diminished with increasing depth.
  • Book
    Dinoflagellate contributions to the deep sea
    (Woods Hole Oceanographic Institution, 1992) Dale, Barrie ; Dale, Amy L. ; Honjo, Susumu
    For the first time, sediment trap samples from several depths in the deep sea were analyzed to estimate both the types and amounts of mineral contributed by dinoflagellates to the deep sea sediment flux. Thecal remains of dinoflagellate motile stages were almost entirely restricted to the upper few hundred meters of the water column, supporting the generally accepted explanation of their absence in the fossil record (i.e., theca are composed of cellulosic material which is destroyed before they may be incorporated into bottom sediments). The main contribution to the sediment flux is composed of resting cysts routinely produced in the life cycles of just a few of the more obscure oceanic dinoflagellates, probably species of Scrippsiella or Ensiculifera. The cyst assemblage sedimenting out from plankton at present is overwhelmingly dominated by a few small calcareous types (up to several thousands/m2/day). If not dissolved, these may accumulate in paleontologically significant amounts in bottom sediments to give the most representative fossil record of oceanic dinoflagellates. "Oceanic assemblages" of organic-walled cysts from Recent deep-sea sediments previously described by palynologists probably represent long distance transport from more coastal regions rather than oceanic dinoflagellate production.
  • Book
    Radiolaria : flux, ecology, and taxonomy in the Pacific and Atlantic
    (Woods Hole Oceanographic Institution, 1991) Takahashi, Kozo ; Honjo, Susumu
    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.
  • Book
    Silicoflagellates and Actiniscus : vertical fluxes at Pacific and Atlantic sediment trap stations
    (Woods Hole Oceanographic Institution, 1991) Takahashi, Kozo ; Honjo, Susumu
    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.
  • Book
    Tintinnids : a taxon-vertical distributional study of settling assemblages from the Panama Basin
    (Woods Hole Oceanographic Institution, 1992) Ling, Hsin Yi ; Honjo, Susumu
    A series of samples collected in sediment traps deployed in the Panama Basin at various depths for 112 days were analyzed to examine the vertical flux of tintinnids, the trumpet-shaped ciliate protozoans. Tintinnids in the 63-250 pm size range reveal that: (1) faunal composition does not change significantly through the water column; (2) at approximately 1,200 m there is a slight increase with depth in the abundance of Codonellopsis, a lorica with a hyaline neck and an agglutinated bowl, and an associated slight decrease in the abundance of Rhabdonella, a lorica consisting entirely of a delicate hyaline nature; and (3) no apparent effect of dissolution was noticed in tintinnid specimens in sediment traps at all depths.