台灣產扁跳蝦屬(端足目：跳蝦科)之新種發表及其關渡地區族群微棲地偏好與族群動群研究

A New Species of Platorchestia (Amphipoda: Talitridae) from Taiwan with Special Reference to Its micro-habitat Preference and Population Dynamics in Guan-du Area

鄭宇庭(Yu-Ting Cheng)

指導教授 ： 林雨德

共同指導教授 ： 陳國勤(Benny K.K. Chan)

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00431

摘要

扁跳蝦屬(Platorchestia Bousfield)是端足目(Amphipoda)中的鈎蝦亞目(Gammaridea)，跳蝦科(Talitridae)。跳蝦科是端足目中唯一有著陸棲與半陸棲物種的類群，常見於上潮間帶、河口沼澤、湖岸溼地以及森林底層之植被枯落物(litters or damp wrack)中，扮演分解植物枯落物的碎屑食者(detritivore)角色，也是鳥類或其他動物重要的食物。關於台灣以往之跳蝦的研究，僅有少數新種發表以及物種描述，至今未有種內之型態變異及族群調查等基礎生態學研究發表。本研究以掃描式電子顯微鏡觀察台灣關渡草澤扁跳蝦(Platorchestia sp.)的形態，並透過COI序列的分析確認本樣本是一個未被描述過的物種，並進一步調查該關渡扁跳蝦族群13個月之群落動態。本研究發現該扁跳蝦近似於日本扁跳蝦(P. japonica)，其第二對觸角完全沒有雌雄二型性，而日本扁跳蝦則具微弱表現，除了大小略小於日本扁跳蝦，型態特徵僅尾板(telson)上的剛毛分布模式有所不同，而與日本扁跳蝦之粒線體序列(COI sequence)存有13.3%的差異，而此差異已達端足目中種間之變異度。 經由體長分析，新種扁跳蝦的每月族群結構約有4個同齡群(cohort)，幾乎每次採樣都有新的同齡群加入，且繁殖中母蝦亦是每月可見，可推論該扁跳蝦族群終年可繁殖，約三個月性成熟，存活時間約八至九個月。 本研究同時測量了該草澤棲地之土壤溫度、酸鹼度、水分含量，水體覆蓋程度，並紀錄植被種類，用以分析新種扁跳蝦之微棲地偏好，分析結果顯示，水體覆蓋程度對扁跳蝦族群之時空分佈的解釋力最好。未來應對台灣各濕地調查跳蝦之分布及種類，並長期觀測動群動態，以確認族群動態是否有明顯之季節變化與年間時空差異。

關鍵字

關渡 ； 草澤 ； 端足類 ； 跳蝦 ； 族群動態 ； 微棲地偏好 ； 底棲

並列摘要

The present study, identified a new Platorchestia sp. from Guan-du, Taiwan, based on morphological (light microscopy and scanning electron microscopy) and molecular approaches (sequence divergence in the mitochondria DNA, COI). I further studied its population dynamics for 13 months (10 sampling periods). Platorchestia sp. nov. from the Guan-du was morphologically different from all reported Platorchestia spp. in the literature, but it was very close to P. japonica. The distribution pattern of spines in the telson, however, exhibited diagnostic differences between the two species. From the sequence divergence in COI, Platorchestia sp. nov. differed from P. japonica 13.3% on average. The values were comparable to inter-specific differences in other amphipod taxa. Population structure of Platorchestia sp. nov. in Guan-du was mainly composed of 4 cohorts, and recruitment occured almost every month through the whole year. Growth rate of juvenile was rapid, obtaining sexual maturity in about 3 months with a longevity 8-9 months. Gravid females were recorded through the whole year, and suggested the species was reproductively active through the year, not seasonally. I examined the effects of water temperature, pH, soil moisture, water level of the substratum, and vegetative type on the distribution pattern of Platorchestia sp. nov. A multivariate analysis indicated that only water level and vegetative type were significant in affecting their abundance. I suggest that to further the understanding of the species future studies should focus on long term population studies to ascertain temporal variations in their life history in Taiwan. Comprehensive survey of the talitrid amphipod species and their distributions in coastal or estuarine marshes in Taiwan would also be fruitful.

並列關鍵字

marsh ； Amphipoda ； Talitridae ； population dynamics ； micro-habitat preference ； macro-fauna ； detritivore

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