TY - JOUR
T1 - Diatom dynamics in a long-lived mesoscale eddy in the northeast subarctic Pacific Ocean
AU - Peterson, Tawnya D.
AU - Harrison, Paul J.
N1 - Funding Information:
We gratefully acknowledge the assistance of the captain, crew, and chief scientists during cruises aboard the CCGS John P. Tully . F. Whitney, A. Pena, and E. Bornhold (Institute of Ocean Sciences) provided significant scientific input during the course of this project. L.A. Miller generously contributed the POC/PN data. The sediment trap material was kindly provided by C.S. Wong and F. Whitney. F.J.R. Taylor kindly made lab space available and gave expert advice with respect to diatom identifications. The work was funded by a Fisheries and Oceans Canada Strategic Grant to PJH , graduate fellowships from the National Science and Engineering Research Council and the University of British Columbia to TDP , and was supported in part through National Science Foundation cooperative agreement OCE-0424602 .
PY - 2012/7
Y1 - 2012/7
N2 - We characterized the diatom flora and determined biogenic silica concentrations within an anticyclonic Haida eddy four times as it drifted westward from the coast of the Queen Charlotte Islands (British Columbia, Canada) into the Alaska Gyre (February 2000-September 2001). For the whole data set (eddy and surrounding waters), diatoms accounted for 6 to 91% of phytoplankton carbon (6-54% total phytoplankton abundance). The proportional contribution of diatoms to phytoplankton carbon within the eddy was higher than in the surroundings inshore of the Transition Zone between coastal and High Nitrate, Low Chlorophyll waters. As the eddy drifted away from the coast and into the Alaska Gyre over the 20-month period, the average biovolume of diatoms decreased by 2-4 times, while in the surroundings a 2-fold increase in average biovolume was observed. The highest diatom abundances were observed in June 2001, when the assemblages were dominated by small colonies of Neodenticula seminae (= Nitzschia cylindroformis) both within the eddy (at the edge and center) and in the surrounding waters. N. seminae lacked the characteristic morphological features of the type species (deck and basal ridges, solid-walled costae) and instead more closely resembled specimens observed for the first time in ~0.8. Ma in the Gulf of St. Lawrence (North Atlantic) in the same year (2001). The corresponding biogenic silica inventories were 10-fold higher in June 2001 compared to the other cruises, yet particulate organic carbon and nitrogen did not increase substantially, potentially indicating a senescing population of diatoms with high Si:C and N. Diatom diversity and evenness indices were lower in June 2001 compared to the other cruises. A combination of high retention, episodic colonization, and significant losses due to sinking or grazing could result in lower diatom abundances but higher diversity observed within the Haida-2000a eddy compared to the surroundings. While silicic acid concentrations may have reached low enough levels to limit diatom growth after an initial spring bloom, levels of this nutrient were not limiting in later observations. Collectively, the data underscore the importance of diatoms in phytoplankton assemblages both close to shore and in High Nitrate, Low Chlorophyll waters.
AB - We characterized the diatom flora and determined biogenic silica concentrations within an anticyclonic Haida eddy four times as it drifted westward from the coast of the Queen Charlotte Islands (British Columbia, Canada) into the Alaska Gyre (February 2000-September 2001). For the whole data set (eddy and surrounding waters), diatoms accounted for 6 to 91% of phytoplankton carbon (6-54% total phytoplankton abundance). The proportional contribution of diatoms to phytoplankton carbon within the eddy was higher than in the surroundings inshore of the Transition Zone between coastal and High Nitrate, Low Chlorophyll waters. As the eddy drifted away from the coast and into the Alaska Gyre over the 20-month period, the average biovolume of diatoms decreased by 2-4 times, while in the surroundings a 2-fold increase in average biovolume was observed. The highest diatom abundances were observed in June 2001, when the assemblages were dominated by small colonies of Neodenticula seminae (= Nitzschia cylindroformis) both within the eddy (at the edge and center) and in the surrounding waters. N. seminae lacked the characteristic morphological features of the type species (deck and basal ridges, solid-walled costae) and instead more closely resembled specimens observed for the first time in ~0.8. Ma in the Gulf of St. Lawrence (North Atlantic) in the same year (2001). The corresponding biogenic silica inventories were 10-fold higher in June 2001 compared to the other cruises, yet particulate organic carbon and nitrogen did not increase substantially, potentially indicating a senescing population of diatoms with high Si:C and N. Diatom diversity and evenness indices were lower in June 2001 compared to the other cruises. A combination of high retention, episodic colonization, and significant losses due to sinking or grazing could result in lower diatom abundances but higher diversity observed within the Haida-2000a eddy compared to the surroundings. While silicic acid concentrations may have reached low enough levels to limit diatom growth after an initial spring bloom, levels of this nutrient were not limiting in later observations. Collectively, the data underscore the importance of diatoms in phytoplankton assemblages both close to shore and in High Nitrate, Low Chlorophyll waters.
KW - Anticyclonic mesoscale eddy
KW - Biogenic silica
KW - Diatom
KW - Gulf of Alaska
KW - HNLC
KW - Neodenticula seminae
KW - Northeast Pacific
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U2 - 10.1016/j.dsr.2012.03.007
DO - 10.1016/j.dsr.2012.03.007
M3 - Article
AN - SCOPUS:84861082885
SN - 0967-0637
VL - 65
SP - 157
EP - 170
JO - Deep-Sea Research Part I: Oceanographic Research Papers
JF - Deep-Sea Research Part I: Oceanographic Research Papers
ER -