高體鰟鮍與青魚捕食福壽螺速率之研究

福壽螺在台灣是有害的外來入侵物種，尤其是對水稻與水生作物的影響，福壽螺也是世界上最具入侵性的前百大物種之一。日本研究指出，鯉科魚類為福壽螺的有效掠食者，因此同為鯉科鰟鮍屬的台灣原生種魚類高體鰟鮍，可能有補食福壽螺的能力。台灣農業改良場的研究資料也指出屬於鯉科的大型青魚會捕食福壽螺，然而高體鰟鮍是否真的可以捕食福壽螺與其捕食速率仍然未知，小型青魚是否能夠捕食福壽螺也仍然未知。至於高體鰟鮍與田蚌存在共生關係之觀察報告，指出高體鰟鮍雌魚會將卵產至田蚌內，受到田蚌保護，田蚌的子代附著在幼魚離開田蚌時一起被帶離，進而擴大田蚌生存空間，上述至今尚未有實際實驗數據證實此現象。因此本研究設計三種試驗包括實驗組與對照組，來驗證上述問題。在高體鰟鮍捕食福壽螺卵試驗中，高體鰟鮍與福壽螺卵被放置於水缸中，並於26天後測量福壽螺卵殘留數量與重量變化。小型青魚捕食福壽螺試驗中，小型青魚與殼高1公分的福壽螺被放置於水缸中，對照組則僅有殼高1公分的福壽螺，並於第0天、第4天、第7天與第10天測量福壽螺存活數量。高體鰟鮍與田蚌共生實驗中，兩個物種被放置於實驗水缸中，每10天觀測子代數量與田蚌移動距離，持續兩個月。結果顯示，高體鰟鮍捕食福壽螺卵在26天後之卵數量減少91.7%，捕食速率為每尾高體鰟鮍每日捕食0.07g福壽螺卵。小型青魚捕食福壽螺實驗得知，小型青魚存在的因子與時間因子都顯著影響福壽螺存活數量，從第3天直到第10天，小型青魚組別中的福壽螺存活數量都顯著低於對照組，顯示小型青魚有效的捕食殼高1公分的福壽螺。共生實驗中則未發現有子代產生，推測在實驗水缸中需要的繁殖子代時間可能更長。本研究證明高體鰟鮍與小型青魚做為捕食福壽螺卵物種的可能性，為防治福壽螺危害農作問題可提供一個新策略。

關鍵字

福壽螺；高體鰟鮍；青魚；田蚌；捕食速率

並列摘要

Pomacea canaliculata is a harmful invasive alien species to the native species in Taiwan, especially the Oryza sativa. Moreover, the P. canaliculata has been listed as one of the top 100 most invasive species in the world. In other words, it is severe problem not only in Taiwan, but also in the world. Previous study suggested cyprinid fishes are predator to the P. canaliculata in Japan. Therefore, Rhodeus ocellatus, a native species in Taiwan, is a potential predator of Pomacea canaliculata since it belongs to the genus of cyprinid fish. The research report from Taiwan Agricultural Research and Extension Station showed Mylopharyngodon piceus, also belonging genus of cyprinid fish, is a predator of P. canaliculata which increases the possibility of R. ocellatus to be a predator of P. canaliculata. However, it is unknow that the predation ability of smaller M. piceus on P. canaliculata and the preying behavior between R. ocellatus and P. canaliculata. The mutualism relationship between R. ocellatus and Sinanodonta woodiana has been found according to the observation report. R. ocellatus injects the eggs into S. woodiana which the shell provides the protection for eggs and newborn fishes. Further, in order to expand S. woodiana population, the larva of S. woodiana attach to the fishes when the newborn fishes grow and swim out of the shell. However, there is not enough scientific evidence to proof the mutualism relationship. The mesocosm was conducted for three experiments to mimic the nature preying and mutualism relationship, respectively. In first experiment, egg of P. canaliculata and adult R. ocellatus were placed into the mesocosm for 26 days. The egg number and weight were measured at beginning of experiment and the end of experiment. In second experiment, 1 cm height P. canaliculata were placed into the mesocosm with or without smaller M. piceus. The survival number of P. canaliculata was counted on day 0, day 4, day 7, and day 10. In the final mutualism experiment, R. ocellatus and S. woodiana were placed into the mesocosm. Offspring number and moving distance of S. woodiana were measured every 10 days until 2 months. Our result indicates that egg of P. canaliculata decreased 91.7% when presents with adult R. ocellatus. The preying rate shows each R. ocellatus ate 0.07 g egg of P. canaliculata per day. Present of smaller M. piceus and time significantly affect the survival number of P. canaliculata in predation experiment of M. piceus. When smaller M. piceus is presente, the survival number of P. canaliculata significantly decreased from day 3 to day 10. Indicating the smaller M. piceus are able to prey 1 cm height P. canaliculata. We did not find the offspring of both R. ocellatus and S. woodiana. It could be due to the demand of reproductive time is higher in the mesocosm condition. Therefore, it might need more time to see the offspring. In conclusion, the present study provides the evidence that proof the ability of R. ocellatus and M. piceus could be a predator for P. canaliculata. Further, it provides a new strategy for future P. canaliculata control.