Effects of temperature and particle size on the filter-feeding rate of brine shrimp Artemia franciscana at different growth stages and stocking densities

Brine shrimp Artemia is able to filter particulate substances non-selectively and continuously, and its filtration capacity is related to various environmental parameters as well as Artemia growth stage. In this study, the filter-feeding rate (FFR) of Artemia franciscana at different temperatures (20°C /25°C /30°C) and stocking densities (200/400/750/1000 ind./L at two earlier growth stages with the body length of 0.91 ± 0.05 mm and 1.53 ± 0.22 mm, respectively; 50/100/200 ind./L at two later growth stages with the body length of 4.72 ± 0.51 mm and 10.26 ± 0.46 mm, respectively) on three unicellular algae (Chlorella vulgaris, Porphyridium purpureum, Phaeodactylum tricornutum) and two sizes of polyethylene beads (30 μm and 50 μm) was determined at Artemia four growth stages. In total 144 combinations were tested. The results showed that the FFR was positively correlated with the ambient temperature and Artemia body length, while it was negatively correlated with the Artemia density and particle size. One way ANOVA analysis showed that ambient temperature, Artemia stocking density and particle size mostly had significant effects on FFR (P < 0.05). And the favorable filtration particle size of Artemia increased with its body length. The equation of FFR in function of temperature (T), Artemia body length (BL) and stocking density (SD), and particle size (PS) was obtained using multiple linear regression analysis: FFR = 0.487* BL + 0.067* T-0.01* SD-0.064* PS-1.508 (R2 = 0.513). Of these four variables, body length had the greatest effect on FFR, followed by ambient temperature, particle size and Artemia density. There were interactions among three factors (T, SD and PS) and the interactive degree varied with Artemia growth. The results of this study provide a valuable guidance for proper feeding in controlled Artemia production and standardization of feeding protocol for ecotoxicity and fundamental Artemia research.