Anthropogenic stressors are increasingly changing conditions and impacting important coastal habitats.

We manipulated light, water temperature, and crustacean grazer propagule supply in an experimental eelgrass system.

Shading reduced primary producer biomass, and had the largest effect overall.

Warming reduced epiphytic algal biomass in the absence of grazers, and increased sessile invertebrate biomass overall.

Propagule supply had no effect on crustacean grazer diversity, relative species abundance, and primary producer biomass.