Particle flux on the continental shelf in the Amundsen Sea and Western Antarctic Peninsula

Date: 
Wednesday, 10 May, 2017 - 15:00 to 16:00
Location: 
NOC Southampton - Henry Charnock Lecture Theatre (Waterfront Campus).
Speaker: 
Professor Hugh Ducklow (http://www.ldeo.columbia.edu/user/hducklow) Lamont Doherty Earth Observatory, Columbia Univ

Particle flux on the continental shelf in the Amundsen Sea and Western Antarctic Peninsula

We report results from a yearlong, moored sediment trap in the Amundsen Sea Polynya (ASP), the first such time series in this remote and productive ecosystem. Resultsare compared to a  long-term (1992-2013) time series from the western Antarctic Peninsula (WAP). The ASP trap was deployed from December 2010 to December 2011 at 350m depth. We observed two brief, but high flux events, peaking at 8 and 5 mmol C m-2 d-1 in January and December 2011, respectively, with a total annual capture of 315 mmol C m-2. Like the overlying phytoplankton bloom observed during the cruise in the ASP (December 2010 to January 2011), particle flux was dominated by Phaeocystisantarctica, which produced phytodetrital aggregates. As the bloom progressed,microscope visualization and stable isotopic composition provided evidence for an increasingcontribution by zooplankton fecal material. Incubation experiments and zooplankton observations suggested that fecal pellet production likely contributed 10-40% of the total fluxduring the first flux event, and could be very high during episodic krill swarms. Independent estimates of export from the surface (100 m) were about 5-10 times that captured in the trap at 350 m. Estimated bacterial respiration was sufficient to account for much of the decline in the flux between 50 and 350 m, whereas zooplankton respiration wasmuch lower. The ASP system appears to export only a small fraction of its production deeper than 350 m within the polynya region.
 
Ducklow HW, Wilson SE, Post AF, Stammerjohn SE, Erickson M, Lee S, Lowry KE, Sherrell RM, Yager PL. 2015. Particle flux on the continental shelf in the Amundsen Sea Polynya and Western Antarctic Peninsula. Elementa 3: 000046.

 

Seminar category: 
POC seminars