Lessonia spicata (
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Photobiological and biochemical analysis data of Lessonia spicata (Valparaíso Bay, 2022)
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The brown seaweed L. spicata (Surh) Santelices (Phaeophyceae, Laminariales) is the most abundant species along the Chilean coast and is distributed from central Chile (29°S) to the south of the Gulf of Penas (46° 59′-47° 40′S) (González et al. 2012; Rosenfeld et al. 2019). Six adults of L. spicata samples were randomly collected in an intertidal zone at a minimum distance of 10 m from the shore along a 70 m transect in Playa Cochoa (Fig. 1A), Valparaíso region (32°57′19"S; 71°32′52"W), during each season in 2022 (summer, autumn, winter and spring) along a daily cycle (at 10:00, 14:00 and 18:00 h, according to Local Time) and in situ physiological measurements were made in a container with 1.5 L of seawater. At the same time, thallus of the L. spicata were frozen in liquid nitrogen and transported in liquid nitrogen to the Laboratory of costal environmental research at Environmental HUB, Universidad de Playa Ancha and preserved at -80°C for biochemical analysis. Seawater temperature, salinity, pH and conductivity were measured using a multiparameter water quality meter (HI 98194, Hanna Instruments, Woonsocket, RI, USA). Changes in the spectral composition of solar radiation PAR radiation (λ = 400–700 nm) and ultraviolet-A and -B (UVA) radiation (λ = 315–400 nm), were quantified through Apogee sensors (Apogee Instruments, USA) with a data logger (HOBO UX120-006M, Onset Computer Corporation, Bourne, MA, USA) according to Celis-Plá et al. (2022). CO2 concentration (ppm) was measured in an equilibration chamber containing 15 g of a fresh weight (FW) sample of L. spicata and 500 mL of water for 1 hour. CO2 was measured directly using a GasScouter G4301 (Picarro, USA) infrared spectrometer, which uses the cavity-ringdown spectroscopy (CRDS) technique (Migné et al. 2007; Davey & Lawson, 2024). The equipment consists of a three-mirror cavity to support a continuous wave path of infrared light, allowing for increased sample sensitivity. Once the gas-phase CO2 concentration was obtained from the equilibrium chamber (Fig. 1B), the mass of assimilated carbon (mg C-CO2/kg according to Stock et al. 2021) produced was determined using the ideal gas equation and mass of carbon in the chamber considering the biomass values (15 g) of L. spicata. In vivo fluorescence of chlorophyll-a (chla) associated with photosystem II (PSII) as an estimator of photosynthetic activity was be determined by using a Mini PAM II portable fluorometer with WinControl-3.2 software (Walz GmbH, Effeltrich, Germany). L. spicata samples were placed in 10 mL incubation chambers with seawater to obtain Rapid Light Curves (RLC) during the daily cycle. The RLCs represent the saturation characteristics of PSII electron transport and overall photosynthetic performance (Celis-Plá et al. 2016). Total internal C and N contents expressed as % of sample dry weight were determined by using an element analyser (model CNHS 932, LECO Corporation, Michigan, USA) according to Celis-Plá et al. (2022).