MEPS 438:129-142 (2011)  -  doi:10.3354/meps09298

Response of the benthic foraminiferal community to a simulated short-term phytodetritus pulse in the abyssal North Pacific

Annekatrin J. Enge1,*, Hidetaka Nomaki2, Nanako O. Ogawa2, Ursula Witte3, Markus M. Moeseneder3,4, Gaute Lavik5, Naohiko Ohkouchi2, Hiroshi Kitazato2, Michal Kučera1, Petra Heinz

1Department for Geosciences, University of Tübingen, Hölderlinstrasse 12, 72074 Tübingen, Germany
2Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
3Oceanlab, University of Aberdeen, Newburgh, Aberdeenshire AB41 6AA, UK
4National Oceanography Centre, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK
5Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany

ABSTRACT: Foraminifera are an important faunal element of the abyssal ecosystem and largely depend on deposited particulate organic matter from the photic zone to sustain their metabolism for growth and reproduction. However, their role in the carbon cycle in deep-sea sediments is insufficiently studied. We investigated benthic foraminifera at Station M (4000 m depth) in the Northeast Pacific and assessed the response of individual species to a simulated phytodetritus pulse during an in situ feeding experiment. Sediments were incubated for 4 d with 13C-labeled diatoms (Thalassiosira weissflogii) applied to the sediment surface. The living foraminiferal community (>0.063 mm) of the upper 3 cm contained >100 species and was strongly dominated by a few taxa of soft-walled saccamminids. Population density of the entire living foraminiferal community was highest at the sediment surface (mean ± SD = 279 ± 72 ind. 10 cm−3 in background and 13C-incubated cores) and decreased gradually with depth. Large differences were observed in the uptake of the algal material among species and between depth levels. During the experiment, 0.82 mg C m−2 were ingested, mainly by calcareous (~60%) and agglutinated (~40%) foraminifera. Uptake was highest at the sediment surface and 3 to 5 times less in deeper sediment horizons. Despite clear signs of vitality and a strong representation in the foraminiferal community, none of the soft-walled species showed a noticeable response to the offered algal material. We conclude that soft-walled foraminifera may not be important to the short-term phytodetrital matter cycling at the abyssal sea floor.

KEY WORDS: Deep sea · North Pacific · In situ feeding experiment · δ13C · Isotopic labeling · Benthic foraminifera · Carbon remineralization · Soft-walled saccamminid

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Cite this article as: Enge AJ, Nomaki H, Ogawa NO, Witte U and others (2011) Response of the benthic foraminiferal community to a simulated short-term phytodetritus pulse in the abyssal North Pacific. Mar Ecol Prog Ser 438:129-142

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