Outdoor cultivation of Ulva lactuca in a recently developed ring-shaped photobioreactor: effects of elevated CO₂ concentration on growth and photosynthetic performance

Abstract

Land-based cultivation of marine macroalgae may open up the possibility to produce high quality algal biomass as required in various application areas all year round. In this context, the potential of a recently developed ring-shaped cultivation system with algae moving in a circular way, simulating the movement pattern in a standard tank cultivation vessel was evaluated using the green alga Ulva lactuca. Plants were cultivated under outdoor conditions at ambient (37 μmol CO2 kg−1 seawater) and increased CO2 concentration (152 μmol CO2 kg−1 seawater). Biomass growth and photosynthetic performance of algae were analyzed over a test period of 7 d. Elevated CO2 concentration significantly stimulated algal growth and also helped to compensate the effects of environmental stress conditions. This was indicated by the predominant stability of photosynthetic competence and represented by maximum photosynthetic electron transport rates, efficiency of light-harvesting and photon fluence rates (PFR) saturating photosynthetic electron transport at low PFR. At high PFR, no difference in photosynthetic competence was detected between algae cultivated at the high CO2-concentration and those grown at ambient CO2. Under elevated CO2 concentrations, photochemical energy dissipation decreased more distinctly at low PFR. This may reflect a declining energy demand necessary to maintain photosynthetic capacity. Under elevated CO2, the apparent changes in the quantum yields of regulated and unregulated non-photochemical energy dissipation of PS II at high PFR possibly reflected the enhanced capacity of photoprotection under the prevailing environmental conditions.

Effects of irradiance, temperature, nutrients, and pCO2 on the growth and biochemical composition of cultivated Ulva fenestrata

“…Increased pCO 2 levels commonly have positive effect on the growth rate of other Ulva species (e.g. Olischläger et al 2013;Young and Gobler 2016;Gao et al 2017Gao et al , 2018bChen et al 2019;Sebök et al 2019), although there are examples were changes in pCO 2 did not have a significant effect (e.g. Kerrison et al 2012;Liu and Zou 2015).…”

“…Growth generally increases with increasing irradiance, temperature, nutrient, and pCO 2 levels (e.g. Duke et al 1986;Geertz-Hansen and Sand-Jensen 1992;Riccardi and Solidoro 1996;Taylor et al 2001;Kalita and Tytlianov 2003;Kalita and Titlyanov 2013;Olischläger et al 2013;Kumari et al 2014;Young and Gobler 2016;Gao et al 2017Gao et al , 2018aTremblay-Gratton et al 2018;Chen et al 2019;Mhatre et al 2019;Sebök et al 2019), although there are exceptions to this general pattern (e.g. Kerrison et al 2012;Liu and Zou 2015).…”

Sustainable Large-Scale Aquaculture of the Northern Hemisphere Sea Lettuce, Ulva fenestrata, in an Off-Shore Seafarm

“…Combining the characteristics of being ubiquitously distributed [20], having a high environmental tolerance and being resistant towards changing abiotic factors [21][22][23], Ulva spp. exhibit high and fast growth rates [18,24] and are capable of thriving under high stocking densities [25,26], which makes them excellent aspirants for large-scale aquacultures.…”

“…in Europe has mainly been limited to coastal nearshore areas (cages, nets) and on-shore tanks, basins or (paddle wheel) pond-based (inand outdoor) cultivation methods [17,24,41,42]. Land-based cultivation systems are especially challenged by their dependence on the massive intake of seawater [43,44] and the distinctive fixed and variable costs for construction, operation and maintenance [24]. Consequently, tank cultivation requires high power inputs and the use of expensive materials and equipment and is, if not operated effectively, in most cases too costly and inappropriate for commercial-scale production of seaweeds [45].…”

Algae Metabolites in Cosmeceutical: An Overview of Current Applications and Challenges

“…Nevertheless, this could be a challenge as well since open cultivation requires extensive use of seawater and the cost for the construction, operation and maintenance of the ponds or tanks is substantial. Open cultivation can cause interferences between algae cultures and the biotic and abiotic environments resulting in low quality of algae produced [155]. Closed cultivation of algae involves stirred tank reactors and closed bubble column photobioreactors for cultivating algal tissue [156].…”