水生寡毛類單孔蚓（Monopylephorus limosus）的生殖和鹽度致死效應

Reproductive Biology and Salinity Tolerance of the Tubificid Oligochaete Monopylephorus limosus

單孔蚓（Monopylephorus limosus）是一種生物學研究甚少的大體型水生寡毛類，本報告探討單孔蚓之生殖生物學和鹽度致死效應。野外採集的蟲體平均體長為3.4±0.9 cm，其卵繭之平均含卵數為9個，多則可達19個，平均卵徑為0.35±0.05 mm；受精卵於實驗室室溫25±2℃的孵化率達86%，9天可發育成幼蚓破繭而出，孵化1天內之幼蚓平均體長為3.5 mm，飼養90天即可成為具生殖能力之成熟個體，此結果顯示單孔蚓的生命週期短且孵化率高。鹽度致死效應結果顯示，單孔蚓無法存活於鹽度大於15 ppt之環境超過15天，與其在野外主要分布於淡水與半淡鹹水河口區之結果相符。 Monopylephorus limosus is a large tubificid oligochaete with little known. This study was intended to investigate its reproductive biology and salinity tolerance under laboratory conditions. The experimental worms collected from fields were 3.4±0.9 cm in length. At temperatures of 25±2℃, numbers of eggs produced per cocoon ranged from 1-19 with an average of 9 eggs. They took 9 days to hatch at a hatching rate of 86%. The 1-day-old hatchlings were about 3.5 mm in length and took about 90 days to reach reproductive maturity. M. limosus has a short life cycle but high reproductive potential. Its maximum salinity tolerance under laboratory condition was 15 ppt, corresponding to that found in fields.