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Brzezinski, M. A., University of California, Santa Barbara, USA, brzezins@lifesci.ucsb.edu
Krause, J. W., University of California, Santa Barbara, USA, krause@lifesci.ucsb.edu
Li, B. ., University of Hawaii, Honolulu, USA, lbinglin@gmal.com
Church, M. J., University of Hawaii, Honolulu, USA, mjchurch@hawaii.edu

INTERANNUAL VARIABILITY AND DRIVERS OF THE SILICON CYCLE AT THE HAWAII OCEAN TIME SERIES STATION ALOHA

A two-year study of the silicon cycle at the Hawaii Ocean Time series station ALOHA sampled a diatom bloom each year during summer coincident with stratification of the upper 50 m and the deepening of isopycnals between 150 and 175 m. Surface maxima in lithogenic silica concentration occurred each spring during the period of high aerosol inputs. Annual silica production varied by only ~30% between years averaging 64 mmol Si m -2 a -1 with the annual diatom bloom accounting for 25% of the total. An average of 54% of annual silica production was exported to 150 m making ALOHA a low-production high-export system relative to biogenic silica. Sea surface high (SSH) anomalies revealed that anticyclones were present at station ALOHA during each diatom bloom similar to past observations that peaks in diazotroph abundances occur during periods of positive SSH anomalies at ALOHA. The high stratification and low nutrient concentrations present during these events would not normally favor diatom growth. Anticyclones may favor diatoms with symbiotic heterocystous cyanobacteria further linking diatom success to N2 fixation at ALOHA.

Session #:S02
Date: 02-18-2011
Time: 09:45

Presentation is given by student: No