紫海膽Anthocidaris crassispina和口鰓海膽Stomopneustes variolaris的生殖週期和晚期幼生餌料實驗

Abstract

從1994年3月到12月，以每月的生殖腺指數和生殖腺切片數據，分析台灣北部野柳(121.4°E, 25.1°N)沿岸紫海膽Anthocidaris crassispina和口鰓海膽Stomopneustes variolaris族群的生殖週期。結果顯示：紫海膽的產卵期為7月至9月，介於日本(32.8°N, 7月至8月)和香港(22.2°N, 6月至10月)的族群之間。口鰓海膽的產卵期為6月至10月，較南非(30.5°S, 12月至l月，)的族群為長。 在6月至9月間，以0.5M KCl注射紫海膽和口鰓海膽，促使其分別排出精和卵，進行人工受精。受精卵孵化後，將浮游的幼生飼養在2L的燒杯中，加1.5L的過瀘海水，水溫為25℃，鹽度為35ppm，攪拌(10rpm)，不照光，每天換水，換燒杯，換水後添加餌料(104 cells/ml的東港等鞭金藻Isochrysis galbana TK1)。至6腕期的晚期幼生以東港等鞭金藻、周氏扁藻Tetraselmis chui，骨藻Skeletonema costalum，進行不同藻種及餌料濃度(104、5×104、105)cells/ml)的實驗。藻種及餌料濃度的複因數實驗結果顯示：以東港等鞭金藻對紫海膽幼生的成長發育最好，且較高的餌料濃度(l05cells/ml)幼生成長較好；而口鰓海膽幼生則適應較低的餌料濃度(104 cells/ml)。根據實驗結果，紫海膽的幼生在水溫24℃，以105 cells/ml的東港等鞭金藻飼育時，在受精後第2天幼生發育至二腕，第3天至四腕，第10天至六腕，第12天至八腕，幼生至第19天時出現雛體，並出現2個叉棘。口鰓海膽幼生以104 cells/ml的東港等鞭金藻飼育，水溫維持在25.0士1.2℃，在受精後第2天幼生發育至二腕，第4天至四腕，第12天至六腕，第14天至八腕，第15天出現第五對腕，幼生發育至第37天可觀察到第六對腕，且部分幼生的形態發育出2-3個叉棘，至第39天可觀察到有雛體的幼生。

Reproduction periodicities of Anthocidaris crassispina (Agassiz) and Stomopneustes variolaris (Lamarck), around the coastal waters of Yeh-liu in northern Taiwan (121.4°E, 25.1°N), were studies by compared with monthly gonad index and histological examination of gonads from March through December 1994. The spawning period of A. crassispina was from July to September, between the populations of Japan (32.8°N, July-Auguest) and Hong Kong (22.2°N, June-October). The spawning season of S. variolaris was from June to October, longer than South African (30.5°S, Decmember-Janunary). Spawning of both sea urchins was initiated by injection of 0.5M KCI solution. Eggs were rinsed with filtered seawater, fertilization with a dilute suspension of sperm, and rinsed several times with filtered seawater (35 ppt S). After hatching, the swimming, pyramidal- shaped larvae were transferred to 2 L beakers filled with 1.5 L of filtered seawater. The seawater in the culture beakers were continuously rotated (10 rpm) at 25℃ in a dark room and renewed every day. After changed the seawater, the microalgae Isochrysis galbana was used as food for larvae at concentrations of 104cells/ml. After 6-arms stage, larvae were processed by feeding different alga species, I. galbana, Tetraselmis chui and Skeletonema costatum, at different concentrations of 104, 5 x 104 and 105 cells/ml. The larvae of A. crassispina, fed on I. galbana, grew best, and better at higher algal concentration (105cells/ml). In contrast, the S. variolaris larvae had the best growth at lower algal concentration (104 cells/ml) and no significant difference between different algal treatments. The larvae of A. crassispina, fed with cells/ml of I. galbana at 24℃, reached the 2-arms pluteus at 2 days, 4-arms stage at 3 d, 6-arms stage at 10 d and 8-arms stage 12 d after fertilization. The ruidiment and 2 pedicellariae appeared at 19 d. The larvae of S. variolaris, reared at 104 cells/ml of I. galbana at 25℃, reached the 2-arms pluteus at 2 days, 4-arms stage at 4 d, 6-arms stage at 12 d and 8-arms stage 14 d after fertilization. The larvae developed 5th-pair arms at 15 d and 6th-pair arms at 37 d. Some larvae grew up 2 or 3 pedicellariae. The larvae with ruidiment were found at 39 d.