The flow of non-living resources between autotrophic and heterotrophic
ecosystems can impact their ecosystem function. However, ecosystem size
is similarly known to influence ecological properties and it is
uncertain how the size of coupled ecosystems mediates the effect of
resource flows. Here, we used a protist experiment to examine how
differences in relative ecosystem sizes mediated the effect of
non-living resource flows on the functioning of two-patch,
autotrophic-heterotrophic meta-ecosystems. We found that when the
autotrophic patch was larger, resource flows between the patches led to
an increase in the total biomass of the meta-ecosystem. Conversely, when
the heterotrophic patch was larger, resource flows decreased the total
biomass of the meta-ecosystem. Patch size also played a critical role in
determining the effects of resource flows on biomass at the ecosystem
level. Our findings reveal that differences in relative ecosystem size
can significantly influence cross-ecosystem dynamics and their
implications for ecosystem function.