Daily changes on seasonal ecophysiological responses of the intertidal brown macroalga Lessonia spicata: Implications of climate change

Abstract

Global climate change is expected to have detrimental effects on coastal ecosystems, with impacts observable at the local and regional levels, depending on factors such as light, temperature, and nutrients. Shifts in dominance between primary producers that can capitalize on carbon availability for photosynthesis will have knock-on effects on marine ecosystems, affecting their ecophysiological responses and biological processes. Here, we study the ecophysiological vulnerability, photoacclimation capacity, and tolerance responses as ecophysiological responses of the intertidal kelp Lessonia spicata (Phaeophyceae, Laminariales) during a year through different seasons (autumn, winter, spring, and summer) in the Pacific Ocean (central Chile). Six different daily cycle experiments were carried out within each season. A battery of different biochemical assays associated with antioxidant responses and in-vivo chlorophyll a fluorescence parameter showed that during spring and summer, there was an increase in photosynthetic capacity in the macroalgae, although their responses varied depending on light and nutrient availability in the course of the year. Lessonia spicata showed maximal photosynthesis and a similar photoinhibition pattern in summer compared to the other seasons, and the contents of nitrate and phosphorous in seawater were less in winter. Thus, high irradiance during spring and summer displayed a higher maximal electron transport rate (ETRmax), irradiance of saturation (Ek), non-photochemical quenching (NPQmax), nitrogen and carbon contents, and photoprotector compound levels. Antioxidant activity increased also in summer, the seasonal period with the highest oxidative stress conditions, i.e., the highest level of hydrogen peroxide (H2O2). In contrast, under low irradiance, i.e., wintertime conditions, L. spicata demonstrated lower concentrations of the photosynthetic pigments such as chlorophyll a and carotenoids. Our study suggests that macroalgae that are subjected to increased irradiance and water temperature under lower nutrient availability mediated by seasonal changes (expected to worsen under climate change) respond with higher values of productivity, pigment contents, and photoprotective compounds. Thus, our findings strengthen the available evidence to predict that algae in the order Laminariales, specifically L. spicata (kelp), could better proliferate, with lower vulnerability and greater acclimation, than other marine species subject to future expected conditions associated with climate change.

Photoprotective responses of three intertidal Antarctic macroalgae to short-term temperature stress

“…Responses of the xanthophyll cycle could reflect a regulatory and photoprotective mechanism that downregulates the delivery of excitation energy into the electron transport chain to match the rates at which products of electron transport can be consumed in these algae (Demmig- Adams and Adams, 2006). In our study, significant Macroalgae can also display phenotypic plasticity, which includes the presence of PCs in brown macroalgae (Goḿez and Huovinen, 2020;Celis-Pláet al, 2022) and MAAs in red seaweeds (Oren and Gunde-Cimerman, 2007;De la Coba et al, 2009). Our findings showed that, in M. hariotii and P. endiviifolia, the concentration of PCs increased at elevated temperatures over time.…”

“…The 2,2-diphenyl-1-picrylhydrazyl (DPPH) method was used as a proxy for determining total antioxidant capacity; the same extracts used for PC determination were used for the total antioxidant capacity assessment (Celis-Pláet al, 2022). Each extract (150 mL) was added to a stock solution of DPPH (1.27 mM concentration; 90 MeOH:10 H 2 O), and the reaction was completed after 30 min in the dark at an ambient temperature (~20°C); the absorbance was read at 517 nm using a microplate reader.…”

“…In red algae, MAA induction is dependent on radiation (Karsten et al, 2003;Figueroa et al, 2014;A ́lvarez-Goḿez et al, 2017), and they exhibit a high antioxidant potential (De la Coba et al, 2009;Carreto and Carignan, 2011). Similarly, phlorotannins, a heterogeneous group of phenolics compounds (PCs) present primarily in brown macroalgae (Pavia and Brock, 2000;Celis-Pláet al, 2022) and some red and green algae (A ́lvarez- Goḿez et al, 2017;Figueroa et al, 2021), have various potential biological activities, including ROS-scavenging potential (Saéz et al, 2015;.…”

An Integrated Approach for the Environmental Characterization of a Coastal Area in the Southern Atacama Desert

“…Lessonia berteroana is widely distributed on hard bottoms in northern Chile [5]. It is an economic and social resource species, common in the intertidal and shallow subtidal zone [6], and has been previously used for biomonitoring through bioaccumulation [7], abundance and morphometric features, fertility and sporophyte formation [8], and ecophysiological traits [9,10]. Microalga biomass is one of the most commonly used attributes in water quality monitoring studies, as it consistently responds to stressors [11] but also serves as an early warning system [12].…”