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This study aimed to evaluate whether polarized light or water turbidity enhances Octopus americanus paralarvae daily feeding rates (FRs) when fed on natural prey (Acartia lilljeborgi copepods) and estimate their daily energy consumption. Paralarva individual FR was obtained using a density of 80 copepods L À1 . The polarized light experiment had a control (regular light) and two polarized light treatments (electronic vectors at 90 and 45 ) for newly-hatched and 15-day-old paralarvae. The water turbidity experiment had a control (0.09 NTU [nephelometric turbidity unit]), and three other treatments (3.80, 19.44, and 45.82 NTU) obtained with different Isochrysis galbana densities for newly-hatched and 8-day-old paralarvae. Five experimental units were used for each treatment and the experiments lasted 24 hr. No significant differences in the FRs were found for polarized light and water turbidity. The general FR was 3.9 ± 2.3, 7.7 ± 2.9, and 15.9 ± 6.5 copepods paralarva À1 day À1 for newly-hatched, 8-day-old, and 15-day-old paralarvae, respectively. Water turbidity at the higher NTU might have impacted swimming performance of paralarvae, reducing their FRs. Our methodological errors for quantifying FRs of paralarvae were <3%, providing

The calanoid copepodNotodiaptomus incompositus(Brian, 1925) is an important contributor in limnic environments in Southern South America, where it can attain high densities and contribute significantly to the total zooplankton biomass in water bodies in Argentina, Uruguay and Brazil. However, little is known about the reproductive biology of this species. In the present study, biological aspects like developmental time, egg production and growth rate were assessed through cultures in the laboratory where copepods were fedChlamydomonascf.pumilioniformis(Chlamydophyceae) cultured in WC medium. The average time of egg incubation was 51 h at 20°C and the mean development time from nauplii to adult was 14 days. The carbon weights ofN. incomposituseggs and females were 0.08 and 2.38 μg C, respectively. The growth rates of all copepodite stages were determined and ranged between 0.073 and 0.447 day−1. This study revealed interesting reproductive aspects of the copepodN. incompositus, generating information that will be of great relevance for future studies with this species.