稀毛蜈蚣藻生活史及養殖育苗技術研究

Abstract

蜈蚣藻屬於紅藻門 (Rhodophyta)、真紅藻綱 (Florideophyceae)、海膜藻目 (Halymeniales)、海膜藻科 (Halymeniaceae)、蜈蚣藻屬 (Grateloupia)，而在台灣，文獻上曾記錄的有六個種類，其中野生的G. livida與G. okamurae已廣泛地被當作食材，而G. sparsa廣泛分佈於東北角及澎湖，其中澎湖發現的藻體體型較東北角大量分布的同一種類大，且葉緣平滑未分枝，外觀與口感也較受人喜愛，因此本研究以澎湖產G. sparsa為實驗材料。按月採樣的野外調查發現，其生長季節為冬季，而生活史所存在的三個世代 (配子體世代、果孢子體世代以及四分孢子體世代) 重疊於這個期間，然而部分的四分孢子體終年可見，但體型較小。同時經由孢子萌發於三種溫度 (20、25、30℃) 及兩種光照 (13.5與40.5 μE/m2/s) 條件下的結果，顯示於較高溫下，雙倍孢子形成的盤狀體較單倍孢子形成的盤狀體較不易形成葉狀體而轉型成結節絲狀體，光照強度並無顯著影響；而單倍盤狀體在較於低溫及較高光照下易產生較多的葉狀體。結節絲狀體可藉SWM-III培養基懸浮培養而大量養殖，在任何時間點下均可利用為種源誘發葉狀體的形成。藉由結節絲狀體的打碎液經噴瓶噴附於尼龍繩上，於25℃下靜置培養至幼葉萌發後，再移至20 ℃下打氣培養成葉狀體幼苗繩，以供野外佈放，其中配子體幼苗經三個月的培養，可達約2.3公分的長度，於四分孢子體幼苗，則因盤狀體較小，易由繩索上脫落，其育苗條件尚未掌握。

Grateloupia spp. belong to the Halymeniaceae family of Rhodophyta, under Florideophyceae and Halymeniales. In Taiwan, 6 species have been recorded, among them, field-collected G. livida and G. okamurae have been utilized as food popularly. One of the widely distributed species along the northern-east coast of Taiwan and at Penghu. G. sparsa at Penghu is larger in size, smooth and branchless, has attrached local consumer by its out-features and texture as food. Based on thes reason, we investigated its life cycle and growth needs in order to develop its propagation. According to the result of field survey, we observed the season of G. sparsa thalli, including gametophyte, carposporophyte and tetrasporophyte is December to March of next year. It was also observed that tetrasporophyte appeared year round, although its size and population were much reduced in Summer. Germinations of carpospore and tetraspore to form young thalli through discoid crust formation were tested under 3 different temperature (20、25、30℃) with 2 illuminations (13.5與40.5 μE/m2/s). The results showed discoid crusts from carpospores were more difficult than those from tetraspores to form young thalli, but easier to form nodulous filament, a multi-crusts form in tangled by their extending filaments at conditions of higher temperature, no significant difference between different illumination. Discoid crusts from tetraspore germinated more young thalli at 20℃and 40.5 μE/m2/s than other combination of temperature and illumination treatment. Nodulous filaments from carpospore or tetraspore thus formed can be propagated by fragmentation and cultured in SWM-III medium. They can be served as germ resources since the filaments can be blended into small piecies and sprayed on nylon ropes for young thalloid germination. Data of the trials of thalloid germination from nodulous filament showed 3~4 days of settlement and discoid formation under 25 ℃ were needed before the nylon ropes were transferred to 20℃, where young thalli grew faster under aeration and illumination. Young thalli of gametophyte grew to 2.3 cm within 3 months and are ready for field test, but the young thalli of tetrasporophyte failed to grow on rope. Young tetrasporophyte were detached grow the rope due to small discoid size.