Understanding the combined effects of global and local stressors is crucial for conservation and management, yet challenging due to the different scales at which these stressors operate.

This study examined the effects of ocean warming on the early life stages of the habitat-forming  macroalga Cystoseira zosteroides, its long-term consequences for population resilience and its combined effect with physical stressors. This was done by exploring the impacts of warming on early life stages and integrating this information into stochastic, density-dependent integral projection models.

The obtained results show that recovery time after a major disturbance significantly increased in warmer scenarios. The stochastic population growth rate was not strongly affected by warming alone, as high adult survival compensated for thermal-induced recruitment failure. Nevertheless, warming,coupled with recurrent physical disturbances, has a strong impact on population growth and viability.

The authors conclude that the impact of warming effects on early stages may significantly decrease the natural ability of habitat-forming algae to rebound after major disturbances. The findings highlight that, in a global warming context, populations of deep-water macroalgae will become more vulnerable to further disturbances, and stress the need to incorporate abiotic interactions into demographic modes.

It is underlined that, given the predictions by this and other studies about the increasing vulnerability of macroalgae, reinforcing their protection against additional human disturbances might make the difference between local extinctions and demographic viability.

https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.13090

Capdevilla et al. (2018) Warming impacts on early life stages increase the vulnerability and delay the population recovery of a long-lived habitat-forming macroalga. Journal of Ecology doi: 10.1111/1365-2745.13090.