| 摘要: | 本研究主要目的為探討台灣石賓對溪流藻類群聚、有機物量與大型無脊椎動物之影響，以了解台灣石賓在溪流生態系中所扮演的角色。本研究於南投縣蓮華池研究中心蛟龍溪溪段內進行，以架設圍網方式進行魚密度試驗，共進行四個實驗處理，魚隻密度分別為0、2、4與6隻。實驗開始後第二、三、四週採集圍網內石頭上之藻類，第四週採集圍網內石頭上之無脊椎動物，並於實驗期間捕捉圍網外之台灣石賓，以分析其胃含物成分。採集後之樣本於實驗室內進行葉綠素a、有機物量以及藻類鑑定與計數等分析，大型無脊椎動物樣本進行鑑定與計數。 研究結果顯示，隨著台灣石賓魚隻密度增加，葉綠素a與有機物量呈現遞減的趨勢，表示台灣石賓在溪流中明顯消耗藻類生物量與有機物量。藻種鑑定結果發現，矽藻皆為主要優勢藻種。在藻類生物體積方面，沒有台灣石賓的實驗處理組，顯著高於其他實驗處理。而在群聚組成上，各處理間藻類組成沒有顯著的差異。大型無脊椎動物組成分析方面，若去除變異差距過大的四個實驗處理組（A1、A6、C1和D1），結果顯示台灣石賓存在時會導致大型無脊椎動物密度顯著下降。分析台灣石賓胃含物組成，發現台灣石賓平均取食矽藻、綠藻與藍綠藻及有機物和砂，並不偏好取食大型無脊椎動物，因此大型無脊椎動物密度隨著台灣石賓魚存在而減少之原因，除了被捕食，亦可能為躲避被捕食而遷移。因此台灣石賓經由攝食減少藻類生物量，進而改變藻類群聚組成，以及影響大型無脊椎動物的密度。
The purpose of this research is to study the effects of Acrossocheilus paradoxus on algae, organic matters, and macroinvertebrates in order to understand the role of A. paradoxus in stream ecosystems. This study was conducted in a section of Jiao-Lung Stream in the Lian-Hua-Chi Research Center in Nantou County of Taiwan. This experiment had 4 treatments with 0, 2, 4, and 6 fish, respectively. Samples were collected on the 2nd, 3rd, and 4th weeks. In the fourth week, macroinvertebrates were collected. The gut contents A. paradoxus form the stream were analyzed . Chlorophyll a, organic matters, algal species identification, and counting were analyzed in the lab. Samples of macroinvertebrates were sorted and identified in the lab. The gut contents of A. paradoxus showed that diatom, green algae, blue green algae, organic matters, and sands were the preferred food items. Only few macroinvertebrates were found in the contents. Experimental results showed that chlorophyll a and organic matters decreased with increasing fish densities, indicating that A. paradoxus reduced the amount of algae and organic matters by consuming them. The control had higher algal biovolumes than other treatments. Algal composition did not differ among treatments and diatom was the dominant algal group. After removing 4 groups (A1, A6, C1 and D1) with great variations, the densities of macroinvertebrates decreased when A. paradoxus was present. |
