Does Copepod Grazing Control Large Phytoplankton in the HNLC Region of the Southern Ocean?

桡足类放牧是否控制了南大洋 HNLC 区域的大型浮游植物？

• 批准号: 9530819
• 负责人: Michael Dagg
• 金额: $ 36万
• 依托单位: Louisiana Universities Marine Corsortium
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-03-15 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9530819&HistoricalAwards=false
• 关键词: Does; Copepod; Grazing; Control; Large

95-30819 DAGG This research project is part of the US Joint Global Ocean Flux Study (JGOFS) Southern Ocean Program aimed at (1 ) a better understanding of the fluxes of carbon, both organic and inorganic, in the Southern Ocean, (2) identifying the physical, ecological and biogeochemical factors and processes which regulate the magnitude and variability of these fluxes, and (3) placing these fluxes into the context of the contemporary global carbon cycle. Large phytoplankton, especially diatoms, typically grow slowly in the permanently ice-free regions of the Southern Ocean, including the Antarctic Polar Front Zone (APFZ), because of micronutrient (Fe) limitation or light limitation or limitation associated with deep mixing. It is hypothesized that under these conditions the growth of large phytoplankton is approximately balanced by grazing from the copepod community. When growth of large phytoplankton is enhanced by Fe inputs or improved light conditions, it is hypothesized that the additional growth is mostly absorbed by the functional response of the copepod community. Larger enhancements of phytoplankton growth however, will saturate the grazing on diatoms increases the Si:C ratio of sinking matter because approximately 70% of ingested carbon is assimilated across the copepod gut wall but Si is digestively inert. These relationships will be addressed by shipboard experiments designed to measure the feeding rates of large copepods on large phytoplankton of the APFZ, and by measurements of the ratio of carbon to biogenic silica in copepod fecal pellets and in sediment trap materials.

95-30819 DAGG该研究项目是美国全球海洋通量联合研究南大洋计划的一部分，旨在（1）更好地了解南大洋有机和无机碳通量，（2）确定调节这些通量的大小和变化的物理、生态和生物地球化学因素和过程，（3）将这些通量置于当代全球碳循环的背景下。 大型浮游植物，特别是硅藻，通常在南大洋的永久无冰区域，包括南极极锋区（APFZ）生长缓慢，因为微量营养素（Fe）限制或光限制或与深度混合有关的限制。据推测，在这些条件下，大型浮游植物的生长是大致平衡的桡足类群落的放牧。当大型浮游植物的生长增强铁输入或改善光照条件，据推测，额外的增长主要是吸收桡足类群落的功能反应。然而，浮游植物生长的更大增强将使硅藻的放牧饱和，从而增加下沉物质的Si：C比，因为大约70%摄入的碳通过桡足类肠壁被同化，但Si具有消化惰性。这些关系将通过船上实验来解决，这些实验旨在测量大型桡足类对APFZ大型浮游植物的摄食率，并通过测量桡足类粪便颗粒和沉积物捕集材料中碳与生物硅的比例。