Effect of environmental history on the habitat-forming kelp Macrocystis pyrifera responses to ocean acidification and warming: a physiological and molecular approach

Pamela A Fernández,Alejandro H Buschmann,Jorge M Navarro,Carolina Camus,Rodrigo Torres

doi:10.1038/s41598-021-82094-7

Abstract

The capacity of marine organisms to adapt and/or acclimate to climate change might differ among distinct populations, depending on their local environmental history and phenotypic plasticity. Kelp forests create some of the most productive habitats in the world, but globally, many populations have been negatively impacted by multiple anthropogenic stressors. Here, we compare the physiological and molecular responses to ocean acidification (OA) and warming (OW) of two populations of the giant kelp Macrocystis pyrifera from distinct upwelling conditions (weak vs strong). Using laboratory mesocosm experiments, we found that juvenile Macrocystis sporophyte responses to OW and OA did not differ among populations: elevated temperature reduced growth while OA had no effect on growth and photosynthesis. However, we observed higher growth rates and NO3− assimilation, and enhanced expression of metabolic-genes involved in the NO3− and CO2 assimilation in individuals from the strong upwelling site. Our results suggest that despite no inter-population differences in response to OA and OW, intrinsic differences among populations might be related to their natural variability in CO2, NO3− and seawater temperatures driven by coastal upwelling. Further work including additional populations and fluctuating climate change conditions rather than static values are needed to precisely determine how natural variability in environmental conditions might influence a species’ response to climate change.

Highlights

The capacity of marine organisms to adapt and/or acclimate to climate change might differ among distinct populations, depending on their local environmental history and phenotypic plasticity
In the present work we investigated and compared the physiological, biochemical and molecular responses of juvenile Macrocystis sporophytes to OW and ocean acidification (OA) from populations naturally exposed to different environmental variability
Our results show that Macrocystis physiological responses to OA and OW did not differ among distinct populations

Summary

Introduction

The capacity of marine organisms to adapt and/or acclimate to climate change might differ among distinct populations, depending on their local environmental history and phenotypic plasticity. Divergent population responses to OA have been observed among calcifying invertebrates and corals that experience different pCO2/pH regimes[24,28,29,30] These responses have been mostly driven by their natural environmental variability (e.g., weak upwelling vs strong upwelling) that influences their tolerance and responses to climate c hange[27]. Kelp ecosystems have been severely affected by OW and marine heat wave events, region-specific responses have been detected, with some kelp populations increasing or remaining stable over the past 50 y ears[55] This suggests that kelp’s responses to global climate changes can be influenced by local driver interactions and by their environmental history as previously shown in key reef-building taxa (corals and coralline algae)[27]

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