In the rainy season they balloon up to the surface 每到雨季 它们便充气浮上水面

139. Any cichlid that trenches out will be snapped up.
     一旦慈鲷切入电场 立刻就会成为捕食的对象
140. The floor of Lake Malawi drops 700 metres into an abyss.
     马拉维湖底是一个深达700多米的深渊
141. Here, in this dead zone the larvae of lake fly midges hide out away from predators.
     这个死亡地带成了 幽蚊幼虫躲避天敌的庇护所
142. In the rainy season they balloon up to the surface
     每到雨季 它们便充气浮上水面
143. and undergo a magical transformation.
     然后经历一场不可思议的变化
144. At dawn the first adult midges start to break out.
     黎明时分 第一只成蚊破蛹而出
145. Soon, millions upon millions of newly hatched lake flies are taking to the wing.
     不久 成百上千万只新羽化的幽蚊 全都扇动着翅膀飞到空中

来自《行星地球 第一季 第三集 Planet Earth S01E03 淡水》第 142 行