Calcareous nannofossils and planktonic foraminifera of ODP Hole 132-810C

The 136 m of calcareous oozes recovered in Hole 810C span the interval from upper Maastrichtian to middle Pleistocene. Three major hiatuses interrupt the sequence, with the topmost part of the Maastrichtian through the entire lower Paleocene, most of the lower Eocene, and the entire middle Eocene through most of the middle Miocene missing. Severe reworking and displacement affected the lower part of the succession from the Maastrichtian through the middle Miocene. Reworking and displacement gradually decreased in the upper portion. Calcareous nannofossil biostratigraphy enabled us to calibrate precisely the nearly complete magnetic reversal sequence of the Pliocene to the late Pleistocene. Two minor hiatuses detected by calcareous nannofossils across the Pliocene/Pleistocene boundary and in the upper lower Pleistocene, respectively, resulted in shortening of the Olduvai and Jaramillo Events within the Matuyama Chron of the magnetic reversal sequence.

Calcareous nannofossil biostratigraphy of ODP Leg 127 sites

Calcareous nannofossils were studied by light microscopy in Neogene sedimentary rocks recovered at four sites of the Ocean Drilling Program Leg 127 in the Japan Sea. Nannofossils occur sporadically at all sites, and allow recognition of seven zones and two subzones; four zones in the Holocene to the uppermost Pliocene, and three zones and two subzones in the middle to lower Miocene. Forty-eight nannofossil species are recognized in 95 of the 808 irregularly-spaced samples taken from all the sites. The nannofossil assemblages in the Miocene are more diverse than those in the Holocene to Pliocene sedimentary interval. The greater diversity and the presence of warm-water taxa, such as Sphenolithus and discoasters in the upper lower Miocene to lower middle Miocene, suggest a relatively warm and stable surface-water condition, attributed to an increased supply of warm water from the subtropical western Pacific Ocean. Site 797 in the southern part of the Yamato Basin contains the most complete and the oldest nannofossil record so far reported from the Japan Sea. The lowermost nannofossil zone at this site, the Helicosphaera ampliaperta Zone (15.7-18.4 Ma) gives a minimum age for the Yamato Basin. This age range predates rotation of southwest Japan, an event previously believed to be caused by the opening of the Japan Sea.

Calcareous nannofossil biostratigraphy of the central East Pacific Rise

During Leg 92 of the Deep Sea Drilling Project, sediments containing calcareous nannofossils of latest Oligocene to Holocene age were recovered from 14 holes at six sites (597 to 602) along the East Pacific Rise. The combined sections yield a virtually complete record for the region, with a compressed upper Miocene to Pleistocene interval. The nannofossil content of 14 U.S.N.S. Eltanin piston cores from the study area were also examined in order to supplement data generated during Leg 92. Two taxonomically new combinations are presented: Sphenolithus umbellus and Pontosphaera segmenta. Assemblages of calcareous nannofossils juxtaposed in reversed stratigraphic order within the upper Miocene provide strong evidence for downslope transport of sediments along the East Pacific Rise during the Messinian. Narrow bands of dark metalliferous sediment of coccolith Zone CN8b alternate with normal light-colored, in situ, pelagic sequences of Zone CN9b. This may indicate more vigorous bottom current activity between 5.40 and 6.70 Ma.

Calcareous nannofossils from the Sumisu Rift and Izu-Bonin Forearc Basin

During Ocean Drilling Program Leg 126, we recovered three expanded Pleistocene sections from the active backarc rift (Sumisu Rift) and three expanded Oligocene-Miocene sections from the forearc basin of the Izu-Bonin volcanic island arc. Quantitative analysis of the Pleistocene nannofossils revealed five major assemblages between 0 and LO Ma: Assemblage 1 (Holocene-0.085 Ma) contains dominant Emiliania huxleyi; Assemblage 2 (ca. 0.085-0.275 Ma) contains dominant small Gephyrocapsa and common E. huxleyi and Gephyrocapsa oceanica; Assemblage 3 (ca. 0.275-0.6 Ma) contains dominant Gephyrocapsa caribbeanica; Assemblage 4 (ca. 0.6-0.9 Ma) contains a peak abundance of small Gephyrocapsa in the middle part, and dominant occurrences of two types of G. caribbeanica in the lower and upper parts; and Assemblage 5 (ca. 0.9-1.0 Ma) contains dominant small Gephyrocapsa and common G. caribbeanica and Reticulofenestra asanoi. These assemblages are largely synchronous with similar assemblages recognized from tropical and subtropical regions, and can be used for finer subdivision of the Pleistocene than that based on standard Pleistocene nannofossil datums. The Oligocene-Miocene sections contain several hiatuses: up to 3 m.y. may be missing from the uppermost Oligocene (Zone CP19) at Sites 792 and 793; all of Zone CN2 is missing at Sites 792 and 793; part of Zone CN3 and all of Zone CN4 are missing at Site 792. Biochronology of several nannofossil datums at Leg 126 sites indicate that Sphenolithus distentus, Sphenolithus ciperoensis, Cyclicargolithus floridanus, and Discoaster kugleri have diachronous occurrences compared with other sites in the western Pacific Ocean and Philippine Sea.

Respiration rates and electron transport system activities of copepod species obtained during Maria S. Merian cruise MSM17/3

Respiration rates and electron transport system (ETS) activities were measured in dominant copepod species from the northern Benguela upwelling system in January-February 2011 to assess the accuracy of the ETS assay in predicting in vivo respiration rates. Individual respiration rates varied from 0.06 to 1.60 µL O2/h/ind, while ETS activities converted to oxygen consumption ranged from 0.14 to 4.46 µL O2/h/ind. ETS activities were significantly correlated with respiration rates (r**2 = 0.79, p = 0.0001). R:ETS ratios were lowest in slow-moving Eucalanidae (0.11) and highest in diapausing Calanoides carinatus copepodids CV (0.76) while fast-moving copepods showed intermediate R:ETS (0.23-0.37). 82% of the variance of respiration rates could be explained by differences in dry mass, temperature and the activity level of different copepod species. Three regression equations were derived to calculate respiration rates for diapausing, slow- and fast-moving copepods, respectively, based on parameters such as body mass and temperature. Thus, knowledge about the activity level and behavioral characteristics of copepod species can significantly increase the predictive accuracy of metabolic models, which will help to better understand and quantify the impact of copepods on nutrient and carbon fluxes in marine ecosystems.