Articles | Volume 14, issue 19
Biogeosciences, 14, 4485–4498, 2017
Biogeosciences, 14, 4485–4498, 2017

Research article 12 Oct 2017

Research article | 12 Oct 2017

The regulation of coralline algal physiology, an in situ study of Corallina officinalis (Corallinales, Rhodophyta)

Christopher James Williamson1,2, Rupert Perkins3, Matthew Voller1, Marian Louise Yallop2, and Juliet Brodie1 Christopher James Williamson et al.
  • 1The Natural History Museum, Department of Life Sciences, Cromwell Road, London SW7 5BD, UK
  • 2School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
  • 3School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3AT, UK

Abstract. Calcified macroalgae are critical components of marine ecosystems worldwide, but face considerable threat both from climate change (increasing water temperatures) and ocean acidification (decreasing ocean pH and carbonate saturation). It is thus fundamental to constrain the relationships between key abiotic stressors and the physiological processes that govern coralline algal growth and survival. Here we characterize the complex relationships between the abiotic environment of rock pool habitats and the physiology of the geniculate red coralline alga, Corallina officinalis (Corallinales, Rhodophyta). Paired assessment of irradiance, water temperature and carbonate chemistry, with C. officinalis net production (NP), respiration (R) and net calcification (NG) was performed in a south-western UK field site, at multiple temporal scales (seasonal, diurnal and tidal). Strong seasonality was observed in NP and night-time R, with a Pmax of 22.35 µmol DIC (g DW)−1 h−1, Ek of 300 µmol photons m−2 s−1 and R of 3.29 µmol DIC (g DW)−1 h−1 determined across the complete annual cycle. NP showed a significant exponential relationship with irradiance (R2 = 0.67), although was temperature dependent given ambient irradiance  > Ek for the majority of the annual cycle. Over tidal emersion periods, dynamics in NP highlighted the ability of C. officinalis to acquire inorganic carbon despite significant fluctuations in carbonate chemistry. Across all data, NG was highly predictable (R2 = 0.80) by irradiance, water temperature and carbonate chemistry, providing a NGmax of 3.94 µmol CaCO3 (g DW)−1 h−1 and Ek of 113 µmol photons m−2 s−1. Light NG showed strong seasonality and significant coupling to NP (R2 = 0.65) as opposed to rock pool water carbonate saturation. In contrast, the direction of dark NG (dissolution vs. precipitation) was strongly related to carbonate saturation, mimicking abiotic precipitation dynamics. Data demonstrated that C. officinalis is adapted to both long-term (seasonal) and short-term (tidal) variability in environmental stressors, although the balance between metabolic processes and the external environment may be significantly impacted by future climate change.

Short summary
Red calcified seaweeds in UK rock pools have seasonal patterns in growth and photosynthesis driven by seawater temperature, light and the chemistry of rock pool water. This is important given future changes in environmental factors such as climate change and ocean acidification. Photosynthesis and calcification are strongly coupled and depend on light and temperature, whilst dissolution is regulated by rock pool water chemistry and is thus particularly vulnerable to environmental change.
Final-revised paper