Adaptation of the Brine Shrimp Artemia Salina (Branchiopoda: Anostraca) to Filter-Feeding: Effects of Body Size and Temperature on Filtration and Respiration Rates

In spite of wide use of the brine shrimp, Artemia salina(Linnaeus, 1758), as feed and model organism in evolutionary, ecological, physiological, and ecotoxicological investigations, only a few studies have attempted to quantify filtration and respiration rates in order to characterize A. salinaas a filter-feeder. Herein, we measured that the maximum filtration rate (F, ml/h) as a function of body length (L, mm) can be expressed by means of two equations, one that applies for small (<2.5 mm) individuals: F = 0. 858 L - 0. 8539, and one for larger juvenile and adult animals: F = 1. 6376 L - 3. 297. An increase from 15 to 25°C resulted in an increase of the filtration rate with a factor of 1.53 ± 0.19, and likewise, a decrease from 30 to 20°C resulted in a decrease of the filtration rate with a factor of 2.16 ± 0.55. The respiration rate (R, Î 1/4g O 2/l) as a function of body length measured on starved A. salinaat 15 and 25°C increases with body length according to R 25 °C = 1. 149 e 0. 528 L and R 15 °C = 1. 243 e 0. 364 L, respectively. The estimated F/R-ratio, which can be used to characterize A. salinaas a filter-feeder, was found to be 7.4 and 6.6 l H 2O/ml O 2at 25 and 15°C, respectively. The relatively low ratios indicate that the animal, which lives in salt lakes, is not well adapted to nourish itself in typical marine areas and is unfit to compete for food with the more advanced copepods and other filter-feeding crustaceans in the sea.