Macrobenthos 339 



deposited in the pond, however, depends to some extent on the weather 

 during late summer. At the beginning of September, the average animal 

 still carried 55 eggs and had already deposited about ten eggs. At the rate 

 of laying of a pair of eggs every 3 days, it is likely that not all eggs were 

 laid before the pond froze unless the weather was unusually warm. 



Production is likely limited by the mortality that occurred during the 

 entire month of July when the pre-adults disappeared into the sediment. 

 The cause for the mortality, a decrease from 30 to 1 animal m\ is not 

 known. There is, however, the possibility of cannibalism, as the largest 

 adult Lepidurus were always found at the same time as the smallest total 

 number of animals. An alternate hypothesis is that there was a food 

 limitation. 



