水庫優養化問題一直以來都是環境保護及水資源相關單位所關切的問題,若水庫中又存在著有害藻種的威脅,對於飲用水安全無疑是一大危機。新山水庫在每年四月下旬有嚴重藍綠藻華現象發生,對於水庫水質造成了莫大的衝擊。所以對於新山水庫,必須了解形成藻華現象的原因,方能採取適當措施,預防優養問題發生。 為釐清造成藻種間消長之原因,本研究藉由在新山水庫進行不同月份的背景採樣,蒐集新山水庫的分層水質資料以及藻類數據。並且蒐集新山水庫之歷史水質與藻類分析資料,將所得的數據進行相關性分析。 本研究根據所蒐集到的藻類數據,分析其數量和體積濃度與環境因子的相關性。再利用藻類所含色素與生理特性之不同,將藻類分成四大類,利用各類藻的出現頻度與體積濃度對環境因子與浮游動物數量做相關性分析。本研究並利用生物多樣性指標Shannon Index及藻種豐度對環境因子做相關性分析,藉此釐清環境物理性因子的變化對藻類多樣性之影響。 經統計分析藻類與環境因子之間的相關性,發現藻類的消長主要與環境物理因子相關,其中水溫分布造成之分層現象,是影響藻類生長之重要因子。在生物多樣性指標方面,發現使用體積密度比所計算出的Shannon Index,對於水庫藻類多樣性能有較好的描述。而且經分析後發現,混合深度及光線在水下之分布是影響藻種豐度多寡之重要因素。
Eutrophication in reservoirs is of great concern in terms of water quality management nowadays. Eutrophication in reservoirs often come with algae bloom, and causes water quality deteriorating. There has been serious cynobacteria bloom taking place in the last couple of weeks of every April in the Hsin-shan reservoir. Consequently, to understand the reason for forming periodic algal bloom, is necessary for improving water quality in this reservoir. There are many factors affecting the phytoplankton succession in reservoirs. In order to understand the relationship among phytoplankton abundance and speciation, and environmental factors in Hsin-shan reservoir, we collected water and plankton samples in every two month. The parameters analyzed include algae speciation, water characteristics and nutrient concentrations. Furthermore, we conducted statistical analyses for these water quality, algal species and nutrient parameter . By dividing algae into four groups on the basis of the pigment difference and physiological characteristics correlation analyses were performed among the abundance, either by frequency of observation or total concentration by volume, water chemical parameters and environmental factors. Finally, biodiversity indicator—Shannon index was used to understand how algal diversity be affected by environmental factors. According to the statistic analyses, it was found that the succession of phytoplankton have great relations with physical characteristics, especially, the vertical profile of temperature, which is an important factor affecting nutrient transfer and phytoplankton mobilization. Shannon Index based on the fraction of the concentration by volume is a more suitable index to describe algae diversity in reservoir. Through investigation on the numbers of algal species and physical characteristics, we found that mixing depth and light attenuation in the water column are important factors affecting the distribution of algae species.