Studies of Energy Flux in Classical and Microbial Food Webs(II)

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Project title

Code/計畫編號

MOST108-2611-M019-014

Translated Name/計畫中文名

副熱帶陸棚浮游生物食物網生態過程研究-子計畫：傳統食物鏈與微生物循環圈能量傳遞過程研究(II)

Project Coordinator/計畫主持人

An-Yi Tsai

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Marine Environment and Ecology

Website

https://www.grb.gov.tw/search/planDetail?id=13122738

Year

2019

Start date/計畫起

01-08-2019

Expected Completion/計畫迄

01-07-2020

Bugetid/研究經費

1500千元

ResearchField/研究領域

海洋科學

本研究想要建立一個簡易的食階模式，來探討傳統食物鏈(植物性浮游生物)及微生物環(纖毛蟲)之能量傳遞過程變化。而此研究更可提供全球相關海洋食物鏈生態探討的可貴數據。本研究模式主要假設大型動物性浮游生物族群主要攝食範圍是> 20 μm的植物性浮游生物。而<20 μm 的植物性浮游生物則是經由纖毛蟲攝食影響而將能量傳遞至大型動物性浮游生物。據此本實驗利用2 種不同濾網大小之分割過濾法 (原水(A)，200 μm濾網過濾後濾液(B)及20 μm濾網過濾後濾液(C))及50 %稀釋培養法(50 %的200 μm過濾後濾液與50% GF/F 濾液混合(D))，來估計植物性浮游生物成長以及能量傳遞的差異。本次實驗培養水樣取自東海南部1A 測站，恰巧採樣時間遇及 2018 年7 月的強烈颱風瑪莉亞，因此特別於颱風前(7 月6 日)及颱風後(7 月16 日)重複於1A 測站進行採樣培養(颱風瑪莉亞經過測站的時間為7 月11 日)，以此進一步比較颱風前後植物性浮游生物成長及能量傳遞是否有明顯差異產生。結果主要發現颱風前後大型動物性浮游生物在此海域對植物性浮游生物是沒有攝食影響的。另實驗結果顯示在颱風前後< 20 μm 葉綠素a 佔整體植物性浮游生物總量分別各為82 %及63 %。經模式估算颱風前後< 20 μm 葉綠素a成長量分別各為22.4 及39.2 mgC m-3 d-1。另外> 20 μm 葉綠素a成長量於颱風前後分別各為10.9 及154.2 mgC m-3 d-1，增加了14倍之多。就纖毛蟲攝食影響而言，颱風前纖毛蟲攝食量約可消耗(<20 μm)植浮52%成長量，另外由於發現纖毛蟲體型在颱風後航次明顯較颱風前大(30 μm:45 μm)。至此本研究推論颱風後纖毛蟲應該能夠攝食>20 μm植浮的部分，因此其攝食量約可消耗(<20 μm + >20 μm)植浮110%成長量。同時此研究重要發現在東海南部海域大型動物性浮游生物攝食的食物來源主要是纖毛蟲，且颱風後纖毛蟲被大型動物性浮游生物攝食量會明顯提高。Mesozooplankton is able to ingest a wide range of food sources, which prey on phytoplankton as well as on different community of protozoans (such as ciliates), connect the microbial food web with the classical phytoplankton-zooplankton-fish food chain. So far, simultaneous estimated grazing impact of mesozooplankton on microbial and classical food webs has seldom been assessed in situ and the relative important of both are remaining uncertain. The model, we assumed that phytoplankton is channeled to higher trophic levels via two ways. One is the role of mesozooplankton in predation on microphytoplankton (> 20 μm) in the grazing food chain. The other is the microbial food chain, which includes components such as pico- and nanophytoplankton (<20 μm) have stressed the importance of predation by ciliates. Four experimental treatments: unfiltered water (treatment A), 200 μm filtered water (treatment B), 20 μm filtered water (treatment C) and 50% dilution experiments (50% of 200 μm filtered water diluted with 50% GF/F filtered water (treatment D)) were incubated for 24 h in 20 liters incubation bottles for measuring the production of phytoplankton and mesozooplankton consumption rate on phytoplankton. Research was conducted aboard the R/V Ocean Research I and samples were collected from the surface waters (5 m) at an established station (Station 1A) located in southern ECS from a pre-typhoon cruise during 4-9 July 2018 and a post-typhoon cruise during 13-17 July 2018. Our results indicated that no significant grazing effects of mesozooplankton on > 20 μm phytoplankton in sized before and after the typhoon samplings. Furthermore, < 20 μm phytoplankton in sized contributed 82% and 63% to total phytoplankton biomass before and after typhoon, respectively. Analysis of model flux showed that production of < 20 μm phytoplankton was 22.4 and 39.2 mgC m-3 d-1 and accounted for 10.9 and 154.2 mgC m-3 d-1 for > 20 μm phytoplankton production before and after typhoon, respectively. As for grazing effect of ciliates, prior to typhoon, ciliates grazed 52% of the < 20 μm phytoplankton production and 110% of total phytoplankton production after the typhoon sampling. Meanwhile, the results of model showed that mesozooplankton feed mostly ciliate communities, especially the consumption rate of mesozooplankton on ciliate increased after the typhoon.

Keyword(s)

傳統食物鏈
微生物循環圈
grazing food chain
microbial loop

DSpace CRIS

Studies of Energy Flux in Classical and Microbial Food Webs(II)

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