Effects of Agriculture on the Abundance and Community Structure of Epilithic Algae in Mountain Streams of Subtropical Taiwan

農業活動對於亞熱帶台灣高山溪流石附生藻類豐度及群集之影響

于淑芬(Shu-Fen Yu) ； 林幸助(Hsing-Juh Lin)

《Botanical Studies》 50卷1期 (2009/01) Pp. 73-87

摘要

武陵地區溪流是瀕臨滅絕台灣櫻花鉤吻鮭的唯一棲地。本研究目的為瞭解該溪流主要初級生產者－石附生藻類之豐度及群集結構，同時探討沿岸農業活動對於石附生藻類之影響。研究發現本區石附生藻類生物量有明顯之季節變化，在春、冬季較高，夏、秋季較低，且具高度農業活動之有勝溪，藻類生物量明顯較其他溪流為高。本區石附生藻類85%是矽藻，其中以Achnanthidium數量最多。石附生藻類群集亦明顯呈現時空變化。以BIOENV分析，發現水溫、導電度、NO2+NO3與SiO2濃度及流速與石附生藻類群集的季節變化最為相關，而影響藻類群集空間分布差異之主要因子為NO2+NO3與SiO2濃度以及藻食者密度。本研究顯示石附生藻類之豐度及群集結構變化可用來監測熱帶及亞熱帶地區高山溪流農業活動的影響。

關鍵字

武陵 ； 矽藻 ； Achnanthidium ； NO2+NO3 ； 流速 ； 藻食者密度

並列摘要

This study aimed to characterize the abundance and community structure of epilithic algae and to examine the effects of intensive agriculture in mountain streams of the Wuling area. There were significant seasonal variations in epilithic algal biomass, with higher values in spring and winter and lower values in summer and fall. Effects of agriculture on the subtropical streams of the Wuling area were significant and varied with the extent of agriculture in the catchment. The biomass was significantly higher in Yousheng Stream with a larger area of agriculture than in other streams. Diatoms were the most abundant species, contributing over 85% to the total cell number. Most of these were pennatae diatoms, of which the genus Achnanthidium was the most abundant in the area. However, the communities showed clear seasonal and spatial changes. BIOENV analysis suggested that the combination of water temperature, conductivity, NO2+NO3 and SiO2 concentrations and current velocity comprised the major factors explaining seasonal changes in the community, while the combination of NO2+NO3 and SiO2 concentration and grazer density comprised the major factors affecting spatial changes. Changes in abundance and community structure of epilithic algae can be used to monitor the effects of agriculture in tropical/subtropical mountain streams.

並列關鍵字

Achnanthidium ； Current velocity ； Diatoms ； Grazer density ； NO2+NO3 ； Wuling