Seasonal variation of diatom assemblages in northeast coast of Taiwan

• Main Author: 王信欽
• Other Authors: 蔣國平
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/93264942921689667001

碩士 === 國立海洋大學 === 漁業科學學系 === 90 === The temporal variation of diatom assemblages at a station on the northeasterern coast of Taiwan was investigated together with hydrographical characteristics during the period from February 2001 to February 2002. Using principal component analyses, 3 water types and 4 diatom assemblages were defined. Water types showed a clear seasonal variation. Two lower temperature water types were found in the winter-spring (2001) and fall-winter (2001-2002), former had higher phosphate concentration while the latter was low in phosphate. A high temperature and low nutrient water type was observed in summer. A two-phased (warm＞22℃; cold＜22℃) seasonal cycle with 4-fold variation was found in the diatom assemblages. In the cold season (winter —spring and fall-winter), when temperature is probably a limiting factor, a low density Background Assemblage existed throughout this period. In warm season, diatom abundance showed a bimodal distribution with two peaks, a Rainy Peak and a Typhoon peak. A total of four diatom assemblages occurred during this period. The Rainy Peak (Rainy Assemblage) was induced by dissolved silica which was brought in by the rain water. The typhoon peak (Typhoon Assemblage) was probably resulted from phosphate regenerated from nanoflagellates and ciliates. The Summer Assemblage was sporadically observed in this season. In addition, the Background Assemblage was also commonly found in the season. Our results suggest that Background Assemblage will change into a new and enhanced assemblage according to various events such as the Typhoon Assemblage and the Rainy Assemblage.