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標題: | 利用衛星遙測技術分析日本鰻棲地品質在中國的長期
變遷 Long-term changes in habitat quality of Japanese eel (Anguilla japonica) in China based on remote sensing technique |
作者: | Yi-Rou Chen 陳怡柔 |
指導教授: | 韓玉山 |
關鍵字: | 日本鰻,棲地品質指數,衛星遙測技術,常態化差異植生指數,棲地破壞, Japanese eel,Habitat Quality Index,satellite remote sensing,Normalized Difference Vegetation Index,habitat destruction, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 日本鰻屬降海產卵型洄游性魚類,為東亞地區高經濟價值魚種。因完全養殖成本過高,目前養殖鰻苗來源仍須仰賴天然資源。然而,自1970 年代起日本鰻天然鰻苗資源量嚴重下降,至今捕獲量不到1970 年代的10%,棲地的破壞對於日本鰻資源量可能會造成非常嚴重的影響,因此,本研究主要由棲地破壞下手。日本鰻主要產地為中國、韓國、台灣及日本,其中中國的資源量約佔60%。本篇研究地點為鴨綠江、長江、閩江、九龍江以及珠江。本研究採用陳等人(2013)創造的一種全新的指標-棲地品質指數(HQI)評估長江棲地品質長期變遷,係利用衛星遙測方法評估日本鰻棲地的破壞程度,不但快速、便利,且可頻繁的監控,再配合上水質汙染指標即可隨時做出適當的應變機制。由於中國目前並沒有官方公布的水質污染資料,本研究利用NDVI與水中總磷之間的相關性分析其優養化程度作為水質汙染參數,並利用NBR與城鎮化之間的相關性,作為河岸水泥化參數,再搭配棲地有效面積評估長江自1970 年代到現代之間的HQI變遷。閩江、九龍江、珠江以及鴨綠江因缺乏實際測量之水質參數,因此以棲地有效面積與河岸水泥化來評估其棲地品質變遷,並將其乘積名為棲地品質容積(HQV)。
結果顯示長江的棲地品質指數自1970年代至2010年代下降69%。閩江與珠江的棲地品質容積自1970年代至2010年代分別下降28%與45%,九龍江與鴨綠江的棲地品質容積自1970年代至2010年代分別上升18%與35%。長江自1990年代之後,優養化比例佔棲地有效面積的一半以上,但在2010年代突然好轉。但是這並不代表長江棲地品質恢復,相反的,這可能代表的是使用NDVI來定義優養化仍存在侷限。2010年代的長江在夏季仍然有藻類孳生,因此,仍有優養化的可能。雖然九龍江、鴨綠江的棲地品質容積上升,但其棲地有效面積較小,能負荷的日本鰻資源量有限,因此長江的棲地對中國的日本鰻還是非常重要的。應盡快納入適當的河川管理, 從流域管理的層面, 考慮生態修復的實施, 避免棲地環境的繼續惡化。 The Japanese eel (Anguilla japonica) is a catadromous fish which is an important aquaculture species in East Asia. Eel fry used in aquaculture can only be obtained via the field capture of glass eels in estuaries because of the high cost of artificial propagation. However, eel stock has been in rapid decline since 1970s which is less than 10% in comparing to that in 1970s. Habitat destruction would pose a threat to eel stock. Thus, the present study start on habitat destruction. The main production place of Japanese eel is China, Korea, Taiwan and Japan. China contributes approximately 60% of the total catch in East Asia. The study area include Yangtze River, Minjiang, Jiulongjiang, Pearl River and Yalu River. The present study adopt Habitat Quality Index (HQI) which developed by Chen (2013) and suggested that by satellite remote sensing and water polluted index, HQI could be used for fast, convenient and largescale Japanese eel habitat evaluation. Because of a lack of long-term water polluted data from official government in China, in present study, we used the long-term Landsat data to measure the Normalized Difference Vegetation Index of water and characterize the changes of total phosphorus concentration (TP). Then, the cemented level of riverbanks is assessed by Normalized Burn Ratio (NBR) and the effective habitat area is assessed by “calculate Geometry” tool by ArcMap. Long-term changes of HQI in Yangtze River since 1970s were assessed to evaluate the long-term eel habitat quality change. Minjiang, Jiulongjiang, Pearl River and Yalu River are assessed by Habitat Quality Volume (HQV), which was calculated from two parameters: the effective habitat area and the cement level of riverbanks, due to the lack of in situ water pollution data. Since 1970s, HQI of the Yangtze River decrease by 69%, the HQV of Minjiang and Pearl River decrease by 28% and 45%. On the other hand, HQVs of Jiulongjiang and Yalu River increase by 18% and 35%. The proportion of eutrophic region is more than half the effective habitat area after 1990s and rapidly improved in 2010s. But it didn’t mean that the habitat quality of Yangtze River began to improve. It is likely that estimating TP by NDVI has a limit. In the slow flowing area, algae can growth in summer and have the chance to cause eutrophication. Although the HQV of Jiulongjiang and Yalu River is rising, the capacity of Japanese eel is limited due to the small effective habitat area. Therefore, the habitat of Yangtze River is still important to Japanese eel. River management plan should be established as soon as possible to slow down the habitat deterioration. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/67945 |
DOI: | 10.6342/NTU201701701 |
全文授權: | 有償授權 |
顯示於系所單位: | 漁業科學研究所 |
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