Organic enrichment reduces microbial diversity and changes community structure and these effects are not mitigated by sediment bioturbators

Here we explored the effect of a common bioturbator, the Sydney cockle (Anadara trapezia), on bacterial and archaeal richness, diversity, evenness, and composition in natural and experimentally enriched sediments. We manipulated both organic enrichment and intra-specific variation of bioturbator body size in a cross-factorial replicated design. A mesocosm experiment was conducted with two treatments of enrichment (natural or spiked with organic matter) fully crossed with 5 bioturbator treatments: 3 cockle body sizes in monoculture (small= 20-30mm, medium= 35-50mm and large= 55-70mm), a treatment with all three sizes represented (i.e. Small+Medium+Large) and a treatment with no cockles that served as a control.