Phosphorus and Iron-Limitation on Phytoplankton Growth (II)

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Project title

Code/計畫編號

NSC93-2611-M019-004

Translated Name/計畫中文名

東海長期觀測與研究(II)---子計畫二：磷與鐵限制浮游植物生長之研究(II)

Project Coordinator/計畫主持人

Jeng Chang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Marine Biology

Website

https://www.grb.gov.tw/search/planDetail?id=1003630

Year

2004

Start date/計畫起

01-08-2004

Expected Completion/計畫迄

01-07-2005

Bugetid/研究經費

1666千元

ResearchField/研究領域

海洋科學

本計劃為東海長期觀測與研究（二）整合型計畫中的子計畫二，目標在界定那一種營養鹽會控制東海中浮游植物的生長，並由此探討東海海域有機碳的流向及食物鍊的結構。在執行的第二年中完成了對東海超微浮游植物時空分佈的調查，發現聚球藻集中出現在 50 m 以淺的水層中，且自大陸沿岸向陸棚中央區逐步增加，然後再向黑潮區逐步減少。原核綠藻則主要分佈於黑潮區的深水層，與聚球藻的分佈極不相同。另外針對渦鞭藻測試了鹼性磷酸脢活性對磷限制的反應，發現鹼性磷酸脢活性在低磷環境下有升高的情形，但是活性的絕對值確和矽藻有所不同。我們提議以額外添加磷酸鹽的方法做為判斷磷限制的依據。這些工作已為進行野外實測做好準備，並已安排於 2005 年三月與六月完成兩個東海航次，實測磷與鐵限制浮游植物生長和分佈的程度。This research is the branch project 2 of the joint research project “Long-term observation and research of the East China Sea – II”. The research goal is to investigate the nutrient species that limit the growth of phytoplankton during the warm seasons in the East China Sea. This information will be used to understand how nutrient limitation influences the carbon flow and food chain structure in this marine ecosystem. During the past year, we investigated the temporal and spatial variations of picoplankton in the southern East China Sea. Our results indicated that Synechococcus mainly distributed in the surface layer with depths shallower than 50 m. Abundances of Synechococcus increased from the coastal zone toward the mid-shelf region where a biomass maximum was observed. Starting from that region, the abundances of Synechococcus decreased toward Kuroshio. In contrast, Prochlorococcus had a very different distribution pattern. It mainly occurred in the Kuroshio with a deep biomass maximum. A second research work was the investigation of alkaline phosphatase activities in a dinoflagellate under phosphate-limiting conditions. Similar to the diatom tested before, dinoflagellate cells under phosphorous stress raised their alkaline phosphatase activities. However, the magnitudes of activities differed between these 2 algae. It is thus quite difficult to set a critical activity level for phosphorous limitation. We propose that a significant decrease in alkaline phosphatase activity when extra phosphate was added before measurement can be used as an alternative criterion. These experimental works are essential to the investigation of nutrient limitation in the East China Sea. Oceanographic cruises have been arranged for field investigations in March and June, 2005.

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Phosphorus and Iron-Limitation on Phytoplankton Growth (II)

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