LIFE-HISTORY TRAITS OF THE TROPICAL FRESH-WATER COPEPOD MESOCYCLOPS-LONGISETUS (CRUSTACEA, COPEPODA)

The life history traits of a tropical copepod population of Mesocyclop s longisetus were measured in the laboratory under defined and control led culture conditions. Egg duration times at 25 and 30-degrees-C were 42.1 and 29.6 hours, respectively. Development times from nauplius I to adult females and males were 22.3 and 18.3 days, respectively. Body sizes (cephalothorax length) of adult females and males were 1.00 and 0.60 mm, respectively. Clutch size averaged 70.2 eggs. Comparison of these traits with those of its congeners reveals considerable life his tory variation in the genus Mesocyclops. Lipid analyses of early stage eggs showed that the percent composition of triglycerides to total li pid in M. longisetus (22%) is similar to that of Mesocyclops edax (17% ) and daphniid cladocerans, but only half that of a marine calanoid co pepod. We suggest that zooplankton may adapt to different resources en vironments by either adjusting their egg size or altering the proporti on of lipid that is readily available for metabolic energy of embryos and nauplii. The diverse arrays of zooplankton life histories may be e xplained in part by adaptations in lipid metabolism in response to the level and predictability of resources.