Effects of increased CO2 levels on growth, photosynthesis, ammonium uptake and cell composition in the macroalga Hypnea spinella (Gigartinales, Rhodophyta)

Abstract

The red seaweed Hypnea spinella (Gigartinales, Rhodophyta), was cultured at laboratory scale under three different CO 2 conditions, non-enriched air (360 ppm CO 2 ) and CO 2 -enriched air at two final concentrations (750 and 1,600 ppm CO 2 ), in order to evaluate the influence of increased CO 2 concentrations on growth, photosynthetic capacity, nitrogen removal efficiency, and chemical cellular composition. Average specific growth rates of H. spinella treated with 750 and 1,600 ppm CO 2 -enriched air increased by 85.6% and 63.2% compared with non-enriched air cultures. CO 2 reduction percentages close to 12% were measured at 750 ppm CO 2 with respect to 5% and 7% for cultures treated with air and 1,600 ppm CO 2 , respectively. Maximum photosynthetic rates were enhanced significantly for high CO 2 treatments, showing P max values 1.5-fold higher than that for air-treated cultures. N-NH 4 + consumption rates were also faster for algae growing at 750 and 1,600 ppm CO 2 than that for non-enriched air cultures. As a consequence of these experimental conditions, soluble carbohydrates increased and soluble protein contents decreased in algae treated with CO 2 -enriched air. However, internal C and N contents remained constant at the different CO 2 concentrations. No significant differences in data obtained with both elevated CO 2 treatments, under the assayed conditions, indicate that H. spinella is saturated at dissolved inorganic carbon concentrations close by twice the actual atmospheric levels. The results show that increased CO 2 concentrations might be considered a key factor in order to improve intensively cultured H. spinella production yields and carbon and nitrogen bioremediation efficiencies.

The short-term effects of elevated CO2 and ammonium concentrations on physiological responses in Gracilariopsis lemaneiformis (Rhodophyta)

“…The same has been reported for Hizikia fusiforme (currently, Sargassum fusiforme), Hypnea spinella, and Pyropia haitanensis (Zou 2005;Suárez-Álvarez et al 2012;Chen et al 2016). Zou et al (2004) showed that the photosynthesis of G. lemaneiformis is already saturated under normal DIC concentrations found in natural seawater.…”

“…Previous studies have revealed similar results with G. lemaneiformis, Hypnea spinella, Chondrus crispus, Pyropia haitanensis, and Ulva pertusa (Yu and Yang 2008;Suárez-Álvarez et al 2012;Sarker et al 2013;Chen et al 2016;Kang and Chung 2017). When DIC concentrations rise in the ocean, many macroalgal species conserve energy by regulating their CCMs, thereby improving their growth performance (Sarker et al 2013).…”

Biochemical composition of temperate and Arctic populations of Saccharina latissima after exposure to increased pCO2 and temperature reveals ecotypic variation

“…The fact that this is the first time that a kelp-specific extraction method is used rendering high efficiency explains why the protein content from both temperate and Arctic S. latissima (Fig. 1) was higher than those reported for most other brown algae except Undaria pinnatifida (Fleurence 1999; Hernández-Carmona et al 2009; Westermeier et al 2012), and similar to values obtained in the red alga Hypnea spinella (Suárez-Álvarez et al 2012). …”

“…In this sense, Olabarria et al (2012) showed that the N-content of the red, respectively, brown seaweed Chondrus crispus and Cystoseira tamariscifolia were positively affected by an increase in pCO 2 , while the red alga Mastocarpus stellatus and the brown seaweeds Sargassum muticum were not affected. On the other hand, the red alga Hypnea spinella responded in a similar way than HL-population at 10 °C, increasing C/N-ratio at elevated pCO 2 conditions, while C-content remain constant (Suárez-Álvarez et al 2012). Experimental studies have shown that responses of internal N-content to CO 2 enrichment vary greatly between different algae (Gordillo et al 1999; Andría et al 2001).…”

Increased CO2 modifies the carbon balance and the photosynthetic yield of two common Arctic brown seaweeds: Desmarestia aculeata and Alaria esculenta

“…Previous evidence of a decrease in respiration rate by high CO 2 concentrations has been reported in vascular plants (Bunce and Caulfield 1991;Azcón-Bieto et al 1994) and in the chlorophyte Ulva rigida (Gordillo et al 2001), in the latter allowing an increase in growth rate despite the unchanged photosynthetic rate, while other macroalgal species did not change their respiration rate when exposed to increased CO 2 (Zou and Gao 2009;Zou et al 2011a;Suárez-Á lvarez et al 2012).…”