Identification of the Relationship Between Environmental Features and Copepod Abundances in the Kuroshio Waters Adjacent to Eastern Taiwan Using Generalized Additive Models

利用泛加成模式探討影響台灣東部黑潮流域橈腳類豐度分布之環境因子特徵

10.29822/JFST.201109.0005

陳郁凱(Yu-Kai Chen)；張以杰(Yi-Jay Chang)；孫志陸(Chi-Lu Sun)；吳繼倫(Chi-Lun Wu)；劉燈城(Dong-Chung Liu)；蘇偉成(Wei-Cheng Su)

黑潮 ； 橈腳類 ； 環境因子 ； 泛加成模式 ； Kuroshio ； Copepod abundances ； Environmental factors ； GAM

臺灣水產學會刊

38卷3期（2011 / 09 / 01）

227 - 237

英文

本研究係使用2005年至2008年間按季於台灣東部黑潮流域所採得之長期、廣範圍的海域環境觀測資料，利用泛加成模式（Generalized Additive Models, GAMs）建立橈腳類豐度與環境因子間的量化關係，並探討各環境因子對橈腳類豐度所造成的不同效應。GAM模式建構係利用階段回推排除法（Backward stepwise elimination）來決定模式中顯著的已知變數，結果顯示各因子對橈腳類豐度變異的相對影響程度排序分別為季節、葉綠素甲濃度、100 m水溫、5 m鹽度、5 m水溫、5 m與100 m水溫差。由GAM分析結果得知台灣東部黑潮流域的橈腳類豐度在夏季至秋季期間最高，冬季最低，且具有明顯的空間分布趨勢，橈腳類豐度高值多伴隨葉綠素甲濃度高、水溫低及鹽度低等環境特徵。整體而言，研究區域西北部近岸區（121.5-122oE, 23.5-24.5On）與西南部近岸區（121-121.5oE, 22-23oN）為橈腳類豐度高值區，此為GAM模式預測之台灣東部黑潮流域橈腳類豐度分布特徵。

Spatial distribution patterns of copepod abundances were analyzed in relation to environmental variables in the Kuroshio waters adjacent to eastern Taiwan. Generalized additive models (GAMs) were applied to examine the relative influence of environmental factors on copepod abundance collected from 2005 to 2008 in this region. To construct a GAM, relationships were analyzed for physical and biotic variables (season, chlorophyll-a concentration, temp at 5 m, temp at 100 m, temp differences between 5 m and 100 m, salinity at 5 m). Stepwise GAM building revealed the relative importance of the variables in explaining the variance in copepod abundance. The variables ranked (1) season, (2) chl-a concentration, (3) temp_100 m, (4) sal_5 m, (5) temp_5 m and (6) temp_diff in decreasing order. Time series of copepod abundance standardized for physical and biotic factors quantified in the GAM implied a seasonal trend, which was highest in summer-autumn period and lowest in winter. The spatial pattern of copepod abundance was characterized by noticeable high abundances associated with higher chlorophyll-a concentration, lower temperature at 5 m and lower salinity at 5 m in the northwestern (121.5-122°E, 23.5-24.5°N) and southwestern (121-121.5°E, 22-23°N) nearshore region of the study area.