GLADIATORS: Glider-based ADaptive sampling of Iron-Algal TransfOrmations in the Ross Sea
|Icebreaker Nathaniel B. Palmer--our home for a month in January-February 2011!|
Josh Kohut, Rutgers University Adam Kustka, Rutgers University Chris Measures, University of Hawaii Allen Milligen, Oregon State University
We will investigate the impacts of deep water intrusions (Modified Circumpolar Deep Water) on ecosystem structure and function within the Ross Sea. Along the AESOPS Ross Sea continental shelf transect (76º 30’), a cluster of stations (a patch) had ~ twice the photosynthetic efficiency and 2- fold greater chlorophyll a than neighboring stations just ~60 km away. This patch was in water with a shallow expression of a warm, salty water mass characteristic of MCDW. The magnitude of the photosynthetic efficiency was correlated with the extent of MCDW shoaling, and stations lacking an underlying MCDW signature had uniformly low photosynthetic efficiency, low chl and few diatoms. From these observations we hypothesize that (1) this intrusion of MCDW serves as a source of Fe to surface waters of vast portions of the Ross Sea, and that (2) MCDW-derived Fe drives ecosystem structure and function by increasing photosynthetic efficiency, photosynthetic rates, chl and by promoting blooms of large diatoms. This is a collaborative effort between 5 institutions. Our role is to collect size-fractionated marine particles for geochemical characterization. We'll analyze the mineralogy of Fe-containing compounds and Nd isotopes in suspended particles to help us determine the source of iron to the Ross sea. We'll also measure particulate organic carbon profiles to see if some areas are transferring more carbon to depth than others. See the outreach page at http://coseenow.net/ross-sea/ for more information about the robotic gliders that will make the job of finding MCDW much easier!