A numerical analysis of carbon dynamics of the Southern Ocean phytoplankton community:: the roles of light and grazing in effecting both sequestration of atmospheric CO2 and food availability to larval krill

被引:64
作者
Walsh, JJ [1 ]
Dieterle, DA [1 ]
Lenes, J [1 ]
机构
[1] Univ S Florida, Dept Marine Sci, St Petersburg, FL 33701 USA
基金
美国国家科学基金会; 美国国家航空航天局;
关键词
Antarctic carbon cycle; food chains; control factors; biological production; krill fisheries; simulation models;
D O I
10.1016/S0967-0637(00)00032-7
中图分类号
P7 [海洋学];
学科分类号
0707 ;
摘要
Reduced ice extent within coastal regions of the Southern Ocean may lead to deeper surface mixed layers (SML), as prevail in offshore areas. A future decline of ice melt-induced stability of the water column may be associated with a shift in dominant food webs, from larger, sun-adapted diatoms grazed by euphausiids to smaller, shade-adapted flagellates consumed by salps. A basically one-dimensional numerical model of three dominant groups of the Antarctic phytoplankton community (diatoms, cryptophytes, and colonial prymnesiophytes) and four types of herbivore (protozoans, salps, copepods, and euphausiids) is used to explore the seasonal importance of both light limitation and grazing pressure on the amount of annual carbon sequestration and larval krill survival within contrasting oceanic and neritic waters, where respective validation data have been gathered during austral spring by the European JGOFS and RACER programs. With imposition of moderate and large grazing stresses, thought to be typical of offshore waters, we were able to replicate the European JGOFS 1992 observations of light penetration, phytoplankton biomass, primary production, pCO(2), bacterial biomass, labile DOG, ammonium, and total particle effluxes at 100 m within the deep SML of our model. The fidelity of such a large set of simulated state variables suggests that multiple limiting factors are indeed operating on different components of the oceanic phytoplankton community - selective grazing losses on the flagellates, but light limitation of diatoms. Release of protozoan grazing pressure in our model instead leads to unobserved spring blooms of cryptophytes, found only in laboratory enclosures. On an annual basis, weak sequestration of atmospheric CO2 is simulated in a habitat typical of the Polar Front, while evasion of carbon dioxide occurs under biophysical conditions of the Antarctic Circumpolar Current. Stratification in shallow SML and the same absolute grazing demands by krill and copepods allows sun-adapted diatoms of our model to bloom at the expense of shade-adapted cryptophytes and prymnesiophytes, eaten by salps and protozoans. We were also able to replicate RACER-I observations of the same suite of variables in 1986-1987, as well as the observed 10-fold range of detrital fluxes caught by other sediment trap deployments during 1980 and 1983 along the Antarctic Peninsula. In western Bransfield Strait, coastal waters are a strong sink for atmospheric CO2 within parcels of Bellingshausen Sea origin, but not perhaps in those from the Weddell Sea, which resemble the oceanic regime of deep SML. We conclude that even in shallow neritic SML. some protozoan rivals of larval krill must still crop flagellates to ensure sufficient abundance of diatom food for both euphausiid survival and possible clogging of the mucous nets of other salp rivals. (C) 2000 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:1 / 48
页数:48
相关论文
共 170 条
[1]  
AGNEW DJ, 1996, FDN ECOLOGICAL RES W, V70, P417
[2]   Antarctic zooplankton metabolism: carbon requirements and ammonium excretion of salps and crustacean zooplankton in the vicinity of the Bransfield Strait during January 1994 [J].
Alcaraz, M ;
Saiz, E ;
Fernandez, JA ;
Trepat, I ;
Figueiras, F ;
Calbet, A ;
Bautista, B .
JOURNAL OF MARINE SYSTEMS, 1998, 17 (1-4) :347-359
[3]   THE TRANSPORT OF ANTHROPOGENIC CARBON-DIOXIDE INTO THE WEDDELL SEA [J].
ANDERSON, LG ;
HOLBY, O ;
LINDEGREN, R ;
OHLSON, M .
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 1991, 96 (C9) :16679-16687
[4]  
[Anonymous], ANTARCTIC RES SERIES
[5]   Primary production in Antarctic sea ice [J].
Arrigo, KR ;
Worthen, DL ;
Lizotte, MP ;
Dixon, P ;
Dieckmann, G .
SCIENCE, 1997, 276 (5311) :394-397
[6]   Changes of carbon dioxide in surface waters during spring in the Southern Ocean [J].
Bakker, DCE ;
DeBaar, HJW ;
Bathmann, UV .
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 1997, 44 (1-2) :91-127
[7]   Low seasonality of low concentrations of surface chlorophyll in the Subantarctic water ring: underwater irradiance, iron, or grazing? [J].
Banse, Karl .
PROGRESS IN OCEANOGRAPHY, 1996, 37 (3-4) :241-291
[8]   Role of protozoan grazing in relieving iron limitation of phytoplankton [J].
Barbeau, K ;
Moffett, JW ;
Caron, DA ;
Croot, PL ;
Erdner, DL .
NATURE, 1996, 380 (6569) :61-64
[9]   SURFACE PH AND PCO(2) DISTRIBUTIONS IN THE BELLINGSHAUSEN SEA, SOUTHERN-OCEAN, DURING THE EARLY AUSTRAL SUMMER [J].
BELLERBY, RGJ ;
TURNER, DR ;
ROBERTSON, JE .
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY, 1995, 42 (4-5) :1093-1107
[10]   Hydrography and biochemical indicators of microplankton biomass in the Bransfield Strait (Antarctica) during January 1994 [J].
Berdalet, E ;
Vaque, D ;
Arin, L ;
Estrada, M ;
Alcaraz, M ;
Fernandez, JA .
POLAR BIOLOGY, 1997, 17 (01) :31-38