The current understanding of multi-stress interplay assumes stresses
occur in perfect synchrony, but this assumption is rarely met in the
natural marine ecosystem. To understand the interplay between
non-perfectly overlapped stresses in the ocean, we manipulated different
temporal scenarios of acidification and assessed their effect on mercury
toxicity in a marine copepod. We found that the scenario of past
acidification aggravated mercury toxicity, but personal and persistent
acidification mitigated the toxicity. This is because personal and
persistent acidification initiated the energy compensation to enhance
growth and mercury efflux. To explore how general temporal scenarios of
acidification affected multi-stress interplay, we conducted a
meta-analysis on marine animals and found that scenarios significantly
changed the toxicity of several other metals. Our study thus
demonstrates that time and duration of stresses modulate multi-stress
interplay in the marine ecosystem, and suggests that future studies
should move beyond the scenario of perfect synchrony.