Cultured and packed sea grapes (Caulerpa lentillifera): effect of different irradiances on photosynthesis

Andreas Kunzmann,Lara Elisabeth Stuthmann,Karin Springer

doi:10.1007/s10811-020-02322-x

Andreas Kunzmann, Lara Elisabeth Stuthmann + Show 1 more

Open Access

https://doi.org/10.1007/s10811-020-02322-x

Copy DOI

Abstract

The green macroalga Caulerpa lentillifera (sea grapes, green caviar) is a promising source for future nutrition due to its beneficial composition for human consumption. It is cultured in tidal ponds, mainly in Vietnam and the Philippines, and stored for shipment and retail in plastic containers, like polystyrene (PS) and polyethylene terephthalate (PET), exhibiting different properties. This study investigates the influence of irradiances on the physiology of sea grapes under culture and packaging ambience in PET using pulse-amplitude modulated (PAM) fluorometry. Fv/Fm values of C. lentillifera significantly decreased < 0.54 ± 0.06 standard deviation (SD) after 7 days of culture under 100 μmol photons m−2 s−1, but with the potential of recovery. In packaging ambience in the state of desiccation, sea grapes exposed to room irradiances (3 μmol photons m−2 s−1) for 12 days were still physiologically in a good condition (Fv/Fm = 0.70 ± 0.06). However, 12 days under irradiances of 70 μmol photons m−2 s−1 leads to decreased Fv/Fm (0.42 ± 0.11) and a moisture content of 88.2 ± 3.3% of initial. After re-immersion in sea water under room irradiances, Fv/Fm values recovered to a certain degree. In darkness, desiccation was followed by a decrease of Fv/Fm to 0.09 ± 0.19 and moisture content of 49.3 ± 20.2% of initial with no recovery after re-immersion under room irradiances. Results suggest shading of C. lentillifera in pond culture and PET containers as suitable packaging for sea grapes, but a dim light source should be provided during storage.

Highlights

Seaweeds as a nutritious and abundant food product are one answer to an explosively growing and hungry world population (Pereira 2020)
The chlorophyll fluorescence parameter maximum quantum yield of photosystem II (PSII) (Fv/Fm) is widely used to assess the photosynthetic efficiency of PSII in dark-adapted leaves, and a decrease of which can be characterized as a result of photoinhibition (Demmig-Adams and Adams 1992; Maxwell and Johnson 2000)
At the farm facility in Van Phong Bay, algae were maintained in shaded tidal ponds (~ 50 μmol photons m−2 s−1), with Fv/Fm values indicating a good physiological state (≥ 0.7, unpublished data)

Summary

Introduction

Seaweeds as a nutritious and abundant food product are one answer to an explosively growing and hungry world population (Pereira 2020). Light is essential for seaweeds to maintain their metabolism, an excess of absorbed photosynthetically active radiation can oversaturate the electron transport chain capacity without driving the biochemical process of photosynthesis (Franklin and Forster 1997). This energy has to be emitted, e.g., through dynamic photoinhibition, a mosaic of photoprotective processes resulting in a declined transfer of excitation energy to the reaction centers in the antenna (non-photochemical quenching) (Osmond 1994; Häder et al 1997; Hanelt et al 1997). The chlorophyll fluorescence parameter maximum quantum yield of PSII (Fv/Fm) is widely used to assess the photosynthetic efficiency of PSII in dark-adapted leaves, and a decrease of which can be characterized as a result of photoinhibition (Demmig-Adams and Adams 1992; Maxwell and Johnson 2000)

Methods

Results

Discussion

Conclusion