Physiological responses of <i>Skeletonema costatum</i> to the interactions of seawater acidification and the combination of photoperiod and temperature

Abstract

Abstract. Ocean acidification (OA), which is a major environmental change caused by increasing atmospheric CO2, has considerable influences on marine phytoplankton. But few studies have investigated interactions of OA and seasonal changes in temperature and photoperiod on marine diatoms. In the present study, a marine diatom Skeletonema costatum was cultured under two different CO2 levels (LC, 400 µatm; HC, 1000 µatm) and three different combinations of temperature and photoperiod length (8:16 L:D with 5 ∘C, 12:12 L:D with 15 ∘C, 16:8 L:D with 25 ∘C), simulating different seasons in typical temperate oceans, to investigate the combined effects of these factors. The results showed that specific growth rate of S. costatum increased with increasing temperature and day length. However, OA showed contrasting effects on growth and photosynthesis under different combinations of temperature and day length: while positive effects of OA were observed under spring and autumn conditions, it significantly decreased growth (11 %) and photosynthesis (21 %) in winter. In addition, OA alleviated the negative effect of low temperature and short day length on the abundance of RbcL and key photosystem II (PSII) proteins (D1 and D2). These data indicated that future ocean acidification may show differential effects on diatoms in different clusters of other factors.

Elevated pCO2 enhances under light but reduces in darkness the growth rate of a diatom, with implications for the fate of phytoplankton below the photic zone

“…Nevertheless, marine diatoms are widespread across the different latitudes and governed by a multitude of environmental cycles which include not only the daily day‐night cycle, but also cycles with shorter or longer periods such as tides, lunar/semi‐lunar cycles or seasons. Prolonged night period during winter has been showed to give rise to growth inhibition under influenced of increased pCO 2 in the diatom of Skeletonema costatum (Li et al 2021), which could be due to negative effects of elevated pCO 2 /pH drop during night (as shown in the present work). It is also worth noting that any opposing effects of increased pCO 2 on diatoms and other microalgae across a day/night cycle might also be influenced by nutrient availability, limitation of which has been shown to enhance respiration under elevated pCO 2 (Li et al 2018).…”

Effects of high temperature stress on conchospore germination and early seedling development ofPyropia haitanensis

“…Thus, 29°C is the highest temperature that can be tolerated for the growth of P. haitanensis conchospore. Short‐term of high temperature can accelerate the absorption and metabolism of nutrients by P. haitanensis conchospores; however, long‐term of high temperature can cause the mortality of conchospores, because of the irreversible damage to conchospore cells imposed by heat stress (Zhou et al, 2022; Li et al, 2021). In addition, high temperature can also lead to cell shrinkage, which results in cell disorder and cytomembrane destruction (Banon et al, 2004).…”

Disentangling the Effects of Ocean Carbonation and Acidification on Elemental Contents and Macromolecules of the Coccolithophore Emiliania huxleyi

“…In terms of ecological implications, the positive correlations between growth rate and rETR max found in E. huxleyi , in the cyanobacterium Microcystis aeruginosa and Pseudanabaena sp. ( Li et al, 2020 ) and in the diatom Skeletonema costatum ( Li et al, 2021 ) suggest that rETR max can be considered as a proxy for growth rate of phytoplankton and may have a potential to predict phytoplankton blooms. Furthermore, no significant differences in protein content, POC/PON ratio, and the contribution of protein–N to PON between present DIC concentration and pH value and ocean acidification treatments suggest that changing ocean carbonate chemistry in a high–CO 2 world in future may have less influence on the nutritional quality of E. huxleyi ( Riebesell et al, 2007 ).…”