Life cycles of marine nematodes : Influence of temperature and salinity in the development of Monhystera denticulata Timm.

Monhystera denticulata Timm, a free-living nematode present in the aufwuchs assemblages of several marine macrophytes located in North Sea Harbor, Southampton, New York, was isolated from Zostera marina and established in laboratory culture in order to study the influences of temperature and salinity on its life history. Under experimental conditions, M. denticulata has a generation time (Measured as the time elapsing between the first egg depositions of consecutive generations) of 10-12 days at 25° C and 26‰ S, which represent optimal growth conditions in the laboratory. The organism has a generation time of 20 days at 25° C and 13‰, 17 days at 25° C and 39‰, 18 days at 15° C and 26‰, 36 days at 15° C and 13‰ and 34 days at 15° C and 39‰. As conditions vary from the optimum of 25° C and 26‰ S, a decrease in temperature of 10° C and an increase or decrease in salinity of 13‰ results in a doubling of the generation time. At 5° C the generation time is about 180-197 days.Assuming optimum conditions and average generation time, about 15 generations of M. denticulata could occur in North Sea Harbor during the year. The number of generations occurring in reality is probably less, however, due to the fact that the females deposit their eggs over a period of several days.