Karl, D. M. University of Hawaii, dkarl@soest.hawaii.edu
Bjorkman, K. M. University of Hawaii, bjorkman@soest.hawaii.edu
Hebel, D. University of Hawaii, dhebel@soest.hawaii.edu
Houlihan, T. University of Hawaii, houlihan@soest.hawaii.edu
Tupas, L. University of Hawaii, ltupas@soest.hawaii.edu

 
SEASONAL AND INTERANNUAL VARIABILITY IN C-N-P STOICHIOMETRY OF DISSOLVED AND PARTICULATE MATTER IN THE SUBTROPICAL NORTH PACIFIC OCEAN
 
Marine biogeochemical models rely on the canonical Redfield ratio (106C:16N:1P) to define ecological stoichiometry. Field observations from a 10-yr biogeochemical time-series investigation at a station in the North Pacific subtropical gyre (Sta. ALOHA; 22.75 N, 158 W) have revealed an unexpected temporal variability in the bulk elemental composition of dissolved and particulate (suspended and sinking) pools, especially in the molar N:P ratios. A distinct seasonal pattern with N:P ranging from 16:1 in winter to >25:1 in late summer is consistent with the previously documented summertime enhancement of nitrogen-fixation at this site. During winter, there is a return to the Redfield ratio as a result of the injection of inorganic nutrients from below the euphotic zone. The seasonal coherence in the bulk bioelemental stoichiometry of dissolved and particulate matter pools suggests a tight coupling and similar residence times. Throughout most of the year, the C:P and N:P ratios of the exported particulate materials are >106:1 and >16:1, respectively, suggesting a decoupling in the near surface C, N and P cycles. Large interannual variations are also evident. All field observations are consistent with P-controlled production and export at Sta. ALOHA. The production and export of organic materials that are enriched in C and N, relative to P, may have important implications to oceanic carbon sequestration in these oceanic biomes.
 
Day: Tuesday, Feb. 2
Time: 02:00 - 02:30pm
Location: Sweeney Center
 
Code: SS49TU0200S