GROWTH AND REPRODUCTION OF THE CLADOCERAN CERIODAPHNIA-DUBIA FROM A FORESTED FLOODPLAIN SWAMP

Microcrustaceans are abundant in many freshwater wetlands, including f orested floodplain swamps, but little has been done to assess their se condary production and functional role in these systems. Since standar d cohort approaches to estimating secondary production are impossible with continuously growing and reproducing microcrustaceans, it is nece ssary to obtain independent determinations of their growth and reprodu ctive characteristics under environmental conditions encountered in th eir natural habitat throughout the year. The growth and reproduction o f Ceriodaphnia dubia fed natural swamp seston were measured at 10, 15, 20, and 25 degrees C-temperatures which span much of the annual tempe rature range in southeastern floodplain swamps. Somatic biomass growth rates were as high as 61% d(-1). Total growth rates (somatic tissue a nd egg mass) reached 95% d(-1). Both somatic growth rates and total gr owth rates could be described as functions of individual size and temp erature. High egg production, particularly in the larger instars, resu lted in individuals maintaining high total growth rates (>20% d(-1) at most temperatures) over the lifespan. Lifetime egg production account ed for >50% of biomass produced by individuals at all temperatures and >80% for temperatures greater than or equal to 20 degrees C. Somatic growth rates for C. dubia fed swamp seston were within the range of li terature estimates for other species of Ceriodaphnia under various foo d conditions.