Selective feeding protects moon jellyfish (Aurelia aurita s.l.) from overloading with microplastics.

Jellyfish blooms may be important bioindicators for marine ecosystem degradation, including the accumulation of microplastics in pelagic food webs. Here we show growth, respiration and filtration rates of the moon jellyfish (Aurelia aurita s.l.) when fed high concentrations (350 L) of zooplankton prey (Artemia salina nauplii) and polystyrene (PS) or reference particles (charcoal; size range 50-500 μm). Our controlled feeding experiments reveal that inedible particles are ingested less efficiently compared to prey (retention efficiency ~60 % for PS) and actively removed from the gastrovascular system of ephyrae and medusae. Increased metabolic demands for excretion of inedible material (up to 76.7 ± 3.1 % of ingested prey biomass) suggest that overloading with microplastics can decelerate growth (observed maxima 26.1 % d and 12.6 % d, respectively) and reproductive rates when food is limited. Possible consequences of this selective feeding strategy in response to proceeding microplastic pollution in the world's future oceans are discussed.