Physiological plasticity and local adaptation to elevated p CO2 in calcareous algae: an ontogenetic and geographic approach

Abstract

To project how ocean acidification will impact biological communities in the future, it is critical to understand the potential for local adaptation and the physiological plasticity of marine organisms throughout their entire life cycle, as some stages may be more vulnerable than others. Coralline algae are ecosystem engineers that play significant functional roles in oceans worldwide and are considered vulnerable to ocean acidification. Using different stages of coralline algae, we tested the hypothesis that populations living in environments with higher environmental variability and exposed to higher levels of pCO ₂ would be less affected by high pCO ₂ than populations from a more stable environment experiencing lower levels of pCO ₂. Our results show that spores are less sensitive to elevated pCO ₂ than adults. Spore growth and mortality were not affected by pCO ₂ level; however, elevated pCO ₂ negatively impacted the physiology and growth rates of adults, with stronger effects in populations that experienced both lower levels of pCO ₂ and lower variability in carbonate chemistry, suggesting local adaptation. Differences in physiological plasticity and the potential for adaptation could have important implications for the ecological and evolutionary responses of coralline algae to future environmental changes.

Keywords: California; life‐history stages; local adaptation; ocean acidification; photosynthesis; physiological plasticity; spore; upwelling.

Figure 1

Temperature, pH, and dissolved pCO ₂ at two intertidal sites located north and south of Point Conception in the California Current Large Marine Ecosystem

Figure 2

Percent growth rate (a) and mortality (b) of spores of Corallina vancouveriensis under high and low pCO ₂ levels. North of Point Conception: Cambria and AG, Arroyo Grande and south of Point Conception: SB, Santa Barbara and Carpinteria (n = 15–17 for SB, n = 14–16 for Carpinteria, n = 5–7 for Cambria, and n = 8–10 for AG, mean ± SE). Shared letters indicate means that were not significantly different after a post hoc comparison

Figure 3

Net photosynthetic productivity (A) and respiration (B) under high and low pCO ₂ levels in adults of Corallina vancouveriensis from sites in California located north (Cambria and Arroyo Grande) and south (Santa Barbara and Carpinteria) of Point Conception (n = 24, mean ± SE). Solid bars represent treatments under high pCO ₂ at the beginning of the experiment (black) and after 30 days (gray). Bars with dots and strips represent treatments under low pCO ₂ at the beginning of the experiment (dots) and after 30 days (strips)

Figure 4

Relative growth rate in adults of Corallina vancouveriensis exposed to high and low pCO ₂ levels. Adults were collected from sites in California located north (Cambria and Arroyo Grande) and south (Santa Barbara and Carpinteria) of Point Conception (n = 24, mean ± SE)

Figure 5

Pigment content in adults of Corallina vancouveriensis exposed to high and low pCO ₂ levels. Adults were collected from sites in California located north (Cambria and Arroyo Grande) and south (Santa Barbara and Carpinteria) of Point Conception (n = 12, mean ± SE). Solid bars represent treatments under high pCO ₂ at the beginning of the experiment (black) and after 30 days (gray). Bars with dots and strips represent treatments under low pCO ₂ at the beginning of the experiment (dots) and after 30 days (strips)