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Distribution and feeding impact on phytoplankton of copepod in waters of western Taiwan
|Authors: ||LI-CHUN TSENG|
|Contributors: ||NTOU:Institute of Marine Biology|
Taiwan;Feeding;Gut content;Distribution;Population;Copepod;Kuroshio;South China Sea;Taiwan Strait;East China Sea
|Issue Date: ||2011-07-04
|Abstract: ||為了瞭解台灣西部海域橈足類群聚的空間分佈與對浮游植物的攝食效應，本研究從 1998 年的 6 月到 2005 年的 12 月在東海、台灣海峽與南海一共進行了六個航次與兩個季節性監測的樣品採集，得到相當豐富的研究結果。 東海具有複雜的海流環境且具有高的生物性生產力與生物多樣性。研究結果顯示長江河口水域的橈足類豐度顯著高於黑潮洋流流域。哲水蚤的 Parvocalanus crassirostris 是東海研究航次中出現度最高與數量最豐富的種類。綜合東海的研究結果發現，橈足類的種類分佈與水團之間有顯著的關聯性。台灣海峽北方海域與黑潮洋流流域的橈足類種類及豐度與中國大陸沿岸區域有顯著的差異。由不同水團中發現各自具有不同指標性橈足類之結果，證明了夏季西南部東海海域的橈足類群聚與水團間具有密切的互動關係。 在台灣海峽的北部區域，季風扮演了影響水團中橈足類種類豐富度與多樣性的重要角色。東北季風與西南季風的盛行把四季的橈足類群聚清楚的分成了四個群組。本研究結果發現黑潮洋流支流對研究區域橈足類群聚的重要影響，橈足類季節間的演替深受東北季風與西南季風的交互作用而產生種類、組成結構改變的現象。 在台灣海峽的南部區域，最優勢的橈足類為 Temora turbinata，在研究期間的所有樣品中具有 > 97 % 的出現率與 75.46 % 的相對豐度。利用 non-metric multidimensional scaling 分析結果發現橈足類的組成具有清楚的季節間差異存在。在污水放流區域發現較低的橈足類的種類數與豐度，這些出現在放流區域的橈足類相較於遠離放流區的測站具有高的相對豐度。這個研究首次提供了橈足類群聚結果在污水放流區環境中具有指標意義的訊息。 南海的橈足類研究結果顯示較高的橈足類多樣性受黑潮洋流及中國大陸注入淡水的影響。來自於亞熱帶與熱帶水團帶來的橈足類在南海的研究區域中具有顯著的優勢性。大多數南海的橈足類在日、夜間不同深度採集的樣品中有明顯的豐度改變，顯示了南海海域的橈足類具有垂直遷移的活動行為。就整體的樣品分析結果發現，表層 (2 – 0 m) 水域相較於深層 (below 50 m) 水域的樣品，發現較少的橈足類種類數與較低的多樣性指數。 關於橈足類的攝食研究，本論文在澎湖群島周圍與南海海域進行了樣品的採集，用來分析橈足類的胃內葉綠素 a 含量、攝食率以及橈足類對浮游植物的攝食效應。橈足類依照體長的大小分成了三個群組 (小型，< 1 mm；中型，1-2 mm 與大型，> 2 mm) 分別進行胃內葉綠素 a 含量、攝食率的分析。結果顯示大型橈足類的胃內葉綠素 a 含量顯著高於小型橈足類。橈足類攝食對浮游植物現存量的攝食效應在測站間具有相當大的差異，結果值範圍介於 0.001 % 到 0.211 % 之間。綜合攝食研究的結果推論，小型橈足類因為在調查水域中具有較高的族群數量，對於浮游植物的攝食效應具有關鍵性的影響力。本論文對於攝食效應偏低的原因也進行深入的討論。|
In order to reveal spatial communities patterns and feeding impact on phytoplankton of copepod in waters of western Taiwan. Six cruises and two seasonal monitor studies were taken in southwest East China Sea, Taiwan Strait and South China Sea from June 1998 to December 2005. The East China Sea is characterized by a complex hydrodynamic regime and high biological productivity and diversity. Copepod abundance was significantly higher in the estuary of the Yangtze River runoff mixture waters and lowest at the Kuroshio Current Region. The calanoid Parvocalanus crassirostris was the most frequently occurring and abundant species. Overall, there was a strong correspondence between the distribution of certain copepod species and water masses. Differences between the Mainland China shelf, the northern Taiwan Strait and the Kuroshio Current Region were characterized by differences in species composition and abundance. Water mass boundaries in the study area were exclusively indicated by distinct differences in species composition, emphasizing a correlation between copepod communities and water masses of the southwest East China Sea in summer. At northern Taiwan Strait, seasonal monsoons play a pivotal role in shaping species richness and diversity of plankton organisms in the water masses. Four copepod communities were distinguished prior to the advent of the northeast or southwest monsoonal winds as well as during the peak period of the respective monsoons. Studied results also reveal the influence of the Kuroshio Branch Current in the study area on copepod assemblages, with seasonal successions being determined by southwestern and by northeastern monsoonal winds. At southern Taiwan Strait, copepod assemblages were dominated by Temora turbinata which occurred in > 97 % samples with a relative abundance of 75.46 % combining all sampling cruises. The ordination diagram derived from non-metric multidimensional scaling separated samples on the basis of season and revealed that different sampling stations clustered differently during each cruise. The outfall area studied here correlates with lower copepod densities represented by a few species that show higher relative abundance in comparison with non-affected areas. Present studies provide the first example where copepod assemblages indicate useful information about environmental changes in the course of sewage disposal at a fixed outlet site. Studied of South China Sea indicated the high copepod diversity in the study area may mainly be caused by both the Kuroshio Current and the fresh water from Mainland China. Water currents in the region transport marine planktonic fauna that comprise predominantly copepod from subtropical and tropical water masses. Most species of copepods performed a common diel vertical migration, descending during daytime and ascending at night at different rates to different depth zones. There were smaller numbers of species and lower diversity indices in surface waters (2 – 0 m) as compared to depths below 50 m. In feeding studied, copepod gut contents, ingestion rates and feeding impact on phytoplankton were estimated at stations off the Pescadores Islands and South China Sea. A size-fractionation approach was applied and the gut pigment contents and ingestion rates were estimated in 3 size categories (small, < 1 mm; medium, 1-2 mm and large, > 2 mm). Results showed gut pigment contents were higher for larger copepods and lower for smaller ones. Feeding impact demonstrated large spatial variability ranging from 0.001% to 0.210% of the chlorophyll a standing stock. The smaller copepod fractions were responsible for most of the feeding impact, due to their numerical dominance in these coastal waters. Variables affecting copepod community feeding impact estimates are discussed.
|Appears in Collections:||[海洋生物研究所] 博碩士論文|
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