Grazing reduces bee abundance and diversity in saltmarshes by suppressing flowering of key plant species

•Livestock grazing in saltmarshes reduces bee abundance and diversity.•Reductions are driven by decreased cover of two key food plants.•Increased plant diversity with grazing does not compensate for negative effects.•Negative effects are stronger at higher grazing intensity.•Ungrazed saltmarshes rank highly for bees compared to terrestrial habitats.