The photosynthetic characteristics of red coralline algae, determined using pulse amplitude modulation (PAM) fluorometry

Abstract

Interest in red coralline algae is increasing due to their projected sensitivity to ocean acidification and their utility as palaeoenvironmental proxies. Thus, it is crucial to obtain a thorough understanding of their basic photosynthetic characteristics and appropriate techniques for use in both laboratory and in situ studies. This study provides fluorescence methodology and data for the ecologically important red coralline alga Lithothamnion glaciale using pulse amplitude modulation (PAM) fluorometry. Lithothamnion glaciale was sufficiently dark-acclimated for in situ work following 10 s of quasi-darkness, attaining 95–98% of the maximum photochemical efficiency (F v/F m). Rapid light curves conducted in situ and in the laboratory determined a low light adaptation, with a saturation intensity of 4.45–54.6 μmol photons m-2 s-1. Intra-thallus heterogeneity was observed between branch tips and bases (i.e., within the thallus) using a custom-made 2 mm fibre optic probe (the heterogeneity could not be detected using the standard 5 mm probe). Branch bases were lower light acclimated than the tips, with higher maximum effective quantum yield (F q′/F m′max) and lower non-photochemical quenching. Samples measured in May were higher light acclimated than in March, which suggests a degree of seasonal acclimation. Light history and photon irradiance levels were thus found to significantly affect the photosynthetic characteristics of L. glaciale.

Dynamic photoinhibition exhibited by red coralline algae in the red sea

“…Previous research, which involved prolonged periods of time in the laboratory [14], may have underestimated the magnitude of dynamic photoinhibition in red coralline algae, because of coralline algal sensitivity to laboratory culture [12]. It should also be noted that a reduction in quantum yield during periods of high irradiance does not imply a reduction in net photosynthesis [40].…”

“…[8-10], and their fundamental role in maintaining ecosystem function [11]. The success and development of coralline algae is, at least in part, driven by photosynthesis, yet comparatively little research has investigated their photosynthetic characteristics [12]. It is generally considered that red coralline algal photosynthesis is optimally adapted to irradiance below that typically experienced in situ [12,13], thus may be particularly susceptible to high-light induced stress [14].…”

Coralline algae (Rhodophyta) in a changing world: integrating ecological, physiological, and geochemical responses to global change

“…Generally, temperate nongeniculate coralline algae are low‐light adapted (Burdett et al. ), and exposure to higher light intensities causes a reduction in photosynthetic activity and bleaching of algal tissue, related to loss of photosynthetic pigments in surface cells (Irving et al. , Martone et al.…”

“…In the temperate rhodolith L. glaciale , within‐thallus variability in light adapta‐tion has been documented, with branch bases less light‐acclimated than the tips (Burdett et al. ). This may translate to differential light availability across the thallus in rhodolith beds.…”

Long‐ and short‐term effects of smothering and burial by drill cuttings on calcareous algae in a static‐renewal test

“…Photosynthetic responses of calcareous algae were assessed by readings of samples, which were 20-min dark-adapted in the laboratory [19]. Chlorophyll-a fluorescence was analyzed using the Diving PAM to investigate stress conditions, because it is a noninvasive, nondestructive technique often used in short-term experiments with calcareous algae [19,20,28]. Bleached patches were avoided because they may represent dead epithelial cells of encrusting calcareous algae [27].…”