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Feeding habits of Diaphus watasei juvenile fish in offshore waters of southwestern Taiwan
|Authors: ||Huang, Ting-Hsuan|
|Contributors: ||NTOU:Department of Environmental Biology and Fisheries Science|
Diaphus watasei;stomach content analysis;stable isotope analyses;feeding strategy
|Issue Date: ||2020-07-02T07:40:32Z
|Abstract: ||眶燈魚屬魚類在海洋食物網中常扮演浮游動物到更高營養階級的能量轉移的角色，豐富的生物量和分布廣泛的特性，使其常在遠洋掠食者胃中發現。本研究於2017年11月至2018年5月及2018年11月至2019年2月採集台灣西南部海域櫻花蝦拖網所捕獲之渡瀨眶燈魚(Diaphus watasei)做為研究對象，利用胃飽滿指數(SCI)、相對重要性指數(IRI)、Costello圖形方法分析其餌料生物組成及攝食習性，並使用歧異度、攝食寬度(Ba)及重疊度(CH)探討體長大小與性別之食性差異及年間變化，同時透過穩定同位素分析探究其營養位階。 研究期間總計蒐集532尾渡瀨眶燈魚進行分析，樣本體長介於57.65mm至115.35mm，其中雄性樣本187尾、雌性樣本345尾。胃飽滿指數(SCI)結果顯示，攝食強度有逐月下降的趨勢，攝食主要的餌料生物為蝦類之櫻蝦(Sergestidae)及魚類之七星底燈魚(Benthosema pterotum)，且在各體長、性別及年間之餌料生物組成皆屬於高度重疊，其可能原因為採樣時體長無法涵蓋更小及更大的範圍或棲息環境之物種組成變動不大，而透過Costello圖形方法可將其定義為對蝦類有專一攝食行為。在穩定同位素方面，氮同位素有隨著體長增加而略微上升的趨勢，但是關係並不顯著，表示餌料生物的組成並沒有隨體長而改變，因此顯現出相似的穩定同位素。平均營養位階為4.1，表示渡瀨眶燈魚在台灣西南部海域為連接二級生產者和上層營養階級之間的物種。綜上所述，透過胃內容物分析及穩定同位素分析對台灣西南部海域生態系統之生物的相互作用及渡瀨眶燈魚之生態更加了解。|
The fish of the genus Diaphus is involved in the transfer of zooplankton to the higher trophic levels in the marine food web. The wide range of characteristics and a rich biomass make its presence very often in the stomach of the top oceanic predators. In this study, we focus on the feeding habit of Diaphus watasei was conducted from November 2017 to May 2018 and November 2018 to February 2019. Samples were collected from the south-western part of Taiwan captured by sakura shrimp trawl. Stomach content index (SCI), relative importance index (IRI), and costello graphical method were used to analyze the prey composition and feeding strategy, and then the differences in body length and sex were investigated using Shannon-Wiener diversity index, diet breadth (Ba) and overlap (CH). A further study on the stable isotope analysis described the trophic position of the species. A total of 532 samples were collected for analysis during the study period including 187 male and 345 female samples with a length range of 57.65mm to 115.35mm. The Stomach Content Index (SCI) showed the decreased feeding intensity month by month with shrimp (Sergestidae spp.) and lantern fish (Benthosema pterotum) as main feeding items in each body length. The prey composition of the diet showed a high overlapping between the sexes, length range and study period. The possible reason for this high overlapping may be associated with the short length range or stable environment. The specific feeding strategy to shrimp can be defined using the “Costello graphic method”. Analysis of stable isotope showed a tendency of slightly increasing of the nitrogen isotope with increased body length but no significant relationship from the statistical analysis indicated no change in the composition of the prey organism with body length, thus showed similar stable isotopes. The average trophic position of 3.1 indicated that the Diaphus watasei in the southwestern part of Taiwan connects the secondary producer and higher trophic level. In summary, the stomach content analysis (SCA) and stable isotope analyses (SIA) shows a better understanding about the interactions between the organisms in the offshore waters of southwestern Taiwan ecosystem and the ecology of the Diaphus watasei.
|Appears in Collections:||[環境生物與漁業科學學系] 博碩士論文|
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