Warming and top predator loss drive direct and indirect effects on multiple trophic groups within and across ecosystems

1. The interspecific interactions within and between adjacent ecosystems strongly depend on the changes in their abiotic and biotic components. However, little is known about how climate change and biodiversity loss in a specific ecosystem can impact the multiple trophic interactions of different biological groups within and across ecosystems. 2. We used natural micro-ecosystems (tank-bromeliads) as a model system to investigate the main and interactive effects of aquatic warming and aquatic top predator loss (i.e., trophic downgrading) on trophic relationships in three integrated food web compartments: i) aquatic microorganisms, ii) aquatic macroorganisms, and iii) terrestrial predators (i.e., via cross ecosystem effects). 3. The aquatic top predator loss substantially impacted the three food web compartments. In the aquatic macrofauna compartment, trophic downgrading increased the filter-feeder richness and abundance directly and indirectly via an increase of detritivore richness, l...