UV-B Resistance in Artemia: A Comparative Analysis Across Altitudinal Gradients, Development Stages, and Reproductive Modes.

The Artemia exhibit broad environmental adaptability and distinct reproductive modes, making them ideal for studying stress tolerance. Solar UV-B radiation poses a threat to aquatic organisms; however, for Artemia-a key aquatic organism characterized by a wide altitudinal distribution range and unique reproductive modes-it remains unclear how their UV-B resistance varies with altitudinal gradients, developmental stages, and reproductive modes. Here, we evaluated six Artemia species/lineages (three bisexual species, three parthenogenetic lineages) from 113 to 4700 m altitude across three developmental stages (embryo, nauplius, adult) under gradient UV-B doses. Key results: (1) UV-B resistance showed a dose-dependent positive correlation with altitude, especially under high-dose UV-B (6.4 kJ·m-2, R2 = 0.72, p < 0.01); (2) Adults had the highest resistance, while nauplii were the most vulnerable; (3) Bisexual species had 41-57% higher adult survival rates than parthenogenetic lineages at similar altitudes, but parthenogenetic lineages showed higher embryo relative hatching rates. These findings clarify the adaptive traits of Artemia in response to UV-B stress.