Effects of photoperiod and light spectra on growth and pigment composition of the green macroalga Codium tomentosum

Abstract

Codium tomentosum is a marine green macroalga with multiple value-added applications that is being successfully used as an extractive species in sustainable integrated multi-trophic aquaculture systems. Nonetheless, growth conditions of this species at an early development phase still require optimization. The present study addresses, under controlled laboratory conditions, the effects of photoperiod (long vs. short-day) and light spectra (white, blue, and red light) on growth and pigment composition of C. tomentosum. Relative growth rate was approximately 2× higher under long-day photoperiod (average of 39.2 and 20.1% week−1 for long and short-day, respectively). Concentrations per dry weight of major pigments such as chlorophyll a (Chla) and siphonoxanthin (Siph) were significantly higher under long-day photoperiod. Relative growth rates were higher under red light, intermediate under white light, and lower under blue light. These last results were rather surprising, as Siph-Chla/Chlb light harvesting complexes of Codium have increased absorption in the blue-green region of the light spectra. Changes in carbon allocation patterns caused by the spectral composition of light and overgrowth of green microalgae in blue light cultures could explain the differences recorded for relative growth rate. Long-day photoperiod and light sources with preferential emission at the red region of the light spectra were identified as optimal for growth of C. tomentosum at early development stages. These lighting conditions can reduce the time required to reach the necessary biomass before transfer to grow-out systems. Overall, these findings can shorten production time, increase macroalgal productivity, and enhance aquaculture revenues.

The underexplored potential of green macroalgae in aquaculture

“…The resulting fragments are subsequently maintained and grown in culture flasks with controlled temperature and lighting conditions, under sufficient aeration to move the fragments inside the culture vessels during the nursery phase. Once fully regenerated, juvenile thalli are transferred to outdoor tanks and grown in free‐floating (tumble culture) conditions in a land‐based IMTA operation 118 . The company ALGAplus Ltd. is dedicated to the aquaculture of organic certified fish (European sea bass and gilthead sea bream) and marine macroalgae native to the NW Atlantic coastal waters.…”

“…Due to the commercial interest in the species, growth conditions for C . tomentosum in IMTA are currently under optimisation towards reduced operational costs and scale‐up 118 …”

Photosynthetic Characteristics of Macroalgae Ulva fasciata and Sargassum thunbergii in the Daya Bay of the South China Sea, with Special Reference to the Effects of Light Quality

“…[12][13][14], serves to energize the photosynthesis of macroalgae, thus regulating the growth and primary productivity [15][16][17]. Apart from the light intensity, the light spectral composition, which varies mainly due to the inherent optical properties of water body and the presence of dissolved and particle matters therein [12][13][14], also influences algal photophysiology and thus their growth, metabolism and productivity [11,[18][19][20][21][22]. Effects of different light wavebands vary, such as in the photosynthetic oxygen evolution in red alga Griffithsia monilis [18] and brown alga Laminaria sp.…”

“…[19]. Blue light inhibits the growth of green alga Codium tomentosum, as compared to red or white light [20], and even shorter wavebands of light reduce the nutrient uptakes of Gracilaria lemaneiformis, as well as the activity of its associated enzymes [23]. On the other hand, macroalgae can also adaptively cope with varying light environments through regulating their morphological, physiological and molecular traits [16,[20][21][22].…”

“…Blue light inhibits the growth of green alga Codium tomentosum, as compared to red or white light [20], and even shorter wavebands of light reduce the nutrient uptakes of Gracilaria lemaneiformis, as well as the activity of its associated enzymes [23]. On the other hand, macroalgae can also adaptively cope with varying light environments through regulating their morphological, physiological and molecular traits [16,[20][21][22]. For instance, in the deep coastal water, where the light is lower but with richer green wavelength, red algae such as Plocamium cartilagineum have additional phycobilisome for light-harvesting complexes [24,25], while brown algae Coilodesme californica and Laminaria sp.…”