Ocean acidification alleviates low-temperature effects on growth and photosynthesis of the red alga Neosiphonia harveyi (Rhodophyta)

Abstract

This study aimed to examine interactive effects between ocean acidification and temperature on the photosynthetic and growth performance of Neosiphonia harveyi. N. harveyi was cultivated at 10 and 17.5 °C at present (~380 µatm), expected future (~800 µatm), and high (~1500 µatm) pCO2. Chlorophyll a fluorescence, net photosynthesis, and growth were measured. The state of the carbon-concentrating mechanism (CCM) was examined by pH-drift experiments (with algae cultivated at 10 °C only) using ethoxyzolamide, an inhibitor of external and internal carbonic anhydrases (exCA and intCA, respectively). Furthermore, the inhibitory effect of acetazolamide (an inhibitor of exCA) and Tris (an inhibitor of the acidification of the diffusive boundary layer) on net photosynthesis was measured at both temperatures. Temperature affected photosynthesis (in terms of photosynthetic efficiency, light saturation point, and net photosynthesis) and growth at present pCO2, but these effects decreased with increasing pCO2. The relevance of the CCM decreased at 10 °C. A pCO2 effect on the CCM could only be shown if intCA and exCA were inhibited. The experiments demonstrate for the first time interactions between ocean acidification and temperature on the performance of a non-calcifying macroalga and show that the effects of low temperature on photosynthesis can be alleviated by increasing pCO2. The findings indicate that the carbon acquisition mediated by exCA and acidification of the diffusive boundary layer decrease at low temperatures but are not affected by the cultivation level of pCO2, whereas the activity of intCA is affected by pCO2. Ecologically, the findings suggest that ocean acidification might affect the biogeographical distribution of N. harveyi.

Seasonal variations of Fucus vesiculosus fertility under ocean acidification and warming in the western Baltic Sea

“…The supply of DIC may have increased -antagonistically to warming -the performance of F. vesiculosus. This finding is consistent with those of Olischläger and Wiencke (2013) and Sarker et al (2013), who examined the combined effects of CO 2 and temperature on Neosiphonia harveyi (Bailey) M.-S. Kim, H.-G. Choi, Guiry & G.W. Saunders and Chondrus crispus Stackh., respectively.…”

Biochemical composition of temperate and Arctic populations of Saccharina latissima after exposure to increased pCO2 and temperature reveals ecotypic variation

“…The former showed that in U. rigida the composition of the phospholipids is changing following cultivation at elevated pCO 2 and attributed this finding to a potential shift in the manner of carbon uptake. Since at low temperatures both the lipid composition of membranes changes (Floreto et al 1993) and the contribution of the CCM to photosynthetic carbon supply decreases (Olischläger and Wiencke 2013b), our findings support this hypothesis. Again, the effect of elevated pCO 2 on the lipid content of S. latissima is ecotype specific, with an insensitive Arctic population and a pCO 2 -sensitive temperate population.…”

Increased CO2 modifies the carbon balance and the photosynthetic yield of two common Arctic brown seaweeds: Desmarestia aculeata and Alaria esculenta

“…On the other hand, the positive effect of elevated CO 2 in the growth rate of A. esculenta has also been observed in many species of seaweeds such as the rhodophytes Lomentaria articulata (Kübler et al 1999), Hypnea spinella (Suárez-Á lvarez et al 2012) and Neosiphonia harveyi (Olischläger and Wiencke 2013), the chlorophyte U. rigida (Gordillo et al 2001) and the brown turf-forming alga Feldmannia sp. (Russell et al 2009).…”

“…Since the effect of OA on growth and photosynthetic performance has shown to be species specific, with some species benefitting and some others showing inhibition or no response, it is supposed that OA might promote changes at the community level (Olischläger and Wiencke 2013).…”