Calanoid Copepod Eggs in Sea-Bottom Muds. IV. Effects of Some Environmental Factors on the Hatching of Resting Eggs

The hatching of resting eggs of 6 species of marine calanoid copepods,Calanopia thompsoni, Labidocera bipinnata, Acartia erythraea, A. clausi, Centropages abdominalis andC. gamadai, recovered from neritic sea-bottom muds in the central part of the Inland Sea of Japan was examined under various environmental conditions (temperature, salinity, oxygen concentration, illumination and presence of bottom mud). Temperature and oxygen concentration were found to be important factors affecting hatching. The respective ranges of temperature in which the eggs of each species hatched correspond closely to the range of temperature at which the planktonic population of that species was observed in the natural environment. Extremely low oxygen concentrations in the water completely inhibited hatching in all species. A wide range or, salinity and the presence or absence of illumination did not prevent hatching.