Environmental Science and Pollution Research

, Volume 25, Issue 33, pp 33361–33369 | Cite as

The impact of elevated atmospheric CO2 on cadmium toxicity in Pyropia haitanensis (Rhodophyta)

  • Haiying Ma
  • Dinghui ZouEmail author
  • Jiayi Wen
  • Zhiwei Ji
  • Jingyu Gong
  • Chunxiang Liu
Research Article


Cadmium is one of the major heavy metal pollutions in coastal waters, and it is well known that cadmium at trace concentration is toxic to macroalgae. Change in marine carbonate system and ocean acidification caused by elevated atmospheric CO2 also alter physiological characteristics of macroalgae. However, less research is focused on the combined impacts of elevated CO2 and cadmium pollution on the growth and physiology in macroalgae. In this study, the maricultivated macroalga Pyropia haitanensis (Rhodophyta) was cultured at three levels of Cd2+ (control, 4 and 12 mg L−1) and two concentrations of CO2, the ambient CO2 (AC, 410 ppm) and elevated CO2 (HC, 1100 ppm). The results showed that 12 mg L−1 Cd2+ significantly suppressed the relative growth rate and superoxide dismutase activity in AC-grown P. haitanensis, while such inhibition extents by Cd2+ were alleviated in HC-grown algae. Cd2+ had no effects on efficiency of electron transport (α) and maximum electron transport rate (ETRmax), but α was increased by elevated CO2. Cd2+ dramatically suppressed the maximum net photosynthesis oxygen evolution rate (NPRm) and the minimum saturation irradiance (Ik) when the algal thalli were grown at AC, while such suppression of NPRm by Cd2+ was much decreased when the thalli were grown at HC. Collectively, our results suggested that elevated CO2 would alleviate Cd2+ toxicity on P. haitanensis.


Elevated CO2 Cadmium toxicity Growth Photosynthesis Antioxidant system Pyropia haitanensis Marine macroalgae 


Pyropia haitanensis is one of the most important species for seaweeds aquaculture in China. This alga has been used as a traditional food material of southern China, being rich in amino acids and minerals such as calcium, magnesium, and zinc, while low in fat (Chen et al. 2011). In addition, P. haitanensis can extract porphyran, a sulfated polysaccharide which possesses excellent antioxidant activity (Zhang et al. 2010). Aquaculture area of P. haitanensis in Shantou City, China, was about 5.4 km2 with 32 million US dollars per year in value, and aquaculture area of Fujian province was ten times that of Shantou (Liu 2017). The macroalgal fields can not only provide various habitats for other plants and animals (Evans et al. 2014) but also prevent and remediate coastal eutrophication by taking up a large amount of N, P, and other nutrients (Chung et al. 2002; Yang et al. 2015). Meanwhile, macroalgae and other marine plants perform good effects on carbon sequestration, acting as an important carbon sink of atmosphere (Chung et al. 2011).

The urbanization and industrialization of coastal areas have brought severe heavy metal pollution to coastal waters, which is an increasingly serious threat to marine ecosystem (Ranjbar Jafarabadi et al. 2017; Qiao et al. 2013). For example, researches showed that Arabian Gulf and coastal areas of South China suffer severe metal contamination, especially cadmium pollution (Naser 2013; Wang et al. 2013). Li et al. (2015) reported that mercury, cadmium, and lead are the predominant heavy metal pollutants in Bohai Bay of northern China. And in southern China, marine cadmium pollution also poses a threat to aquatic organisms (Wang et al. 2013). Cadmium was proved to have toxic effects on marine plants. It was shown that, when treated with cadmium, DNA was damaged in phytoplankton (Babu et al. 2014).Two-hour 25 μM cadmium exposure could up-regulate the transcripts of both nuclear- and chloroplast-encoded genes (Rubinelli et al. 2002). Bouzon et al. (2012) reported that the growth rate and the contents of photosynthetic pigments were reduced in Hypnea musciformis when exposed to cadmium. Moreover, under Cd2+ treatment, Ulva linza showed reductions in Fv/Fm, relative growth rate, and actual photochemical efficiency of PSII (Jiang et al. 2013).

Frequent and intensive human activities have caused not only heavy metal pollution (Ranjbar Jafarabadi et al. 2017) but also CO2 elevation in the atmosphere (Bedir and Yilmaz 2016). Elevating atmospheric CO2 over the last century has changed the marine carbonate system and decreased pH of surface water, which further affected marine ecosystem (Fabry et al. 2008). Studies have shown that ocean acidification inhibited the growth of coralline algae (Ragazzola et al. 2012) but might be beneficial to other algae, thereby changing the benthic community structure in shallow-water ecosystem (Kuffner et al. 2008; Price et al. 2011). In addition, high concentration of CO2 might promote the photosynthesis process of marine macroalgae, but this promotion depends on the species (Zou and Gao 2002).

Cadmium pollution in coastal water and elevated CO2 in atmosphere may affect each other. Elevated CO2-induced ocean acidification released the cadmium and other heavy metals from sediment, elevating their concentrations in sea water (Millero et al. 2009). At the same time increasing cadmium induced the change the marine inorganic carbon system (Zheng et al. 2009). Researches also showed that cadmium may replace the role of zinc in carbonic anhydrase to convert HCO3 into CO2 (de Baar et al. 2017). How will marine macroalgae respond to the combined impacts of elevated atmospheric CO2 and cadmium pollution? Nevertheless, this interesting issue has mainly been remained as unexplored. As an economically important macroalgal species, P. haitanensis, the effects of CO2 elevation on growth and photosynthesis have been attracted much attention (Xu et al. 2017). However, none of the previous studies paid attention on the combined effects of cadmium pollution and elevated CO2 on macroalgae such as P. haitanensis. In this paper, we cultured P. haitanensis at two levels of CO2 and three cadmium concentrations, and the physiological indications such as the growth, photosynthesis, and antioxidant enzymes activity were measured, in an effort to shed light on the possible combined effects of atmospheric CO2 elevation and cadmium pollution on the growth and physiology of P. haitanensis.

Materials and methods

Algae collection and experimental design

Pyropia haitanensis was collected from Shen’ao Bay (117.1 E, 23.5 N), Shantou, China, and was transported to the laboratory in a clean sampling case under 4 °C within 6 h. The algal thalli were maintained in an intelligent artificial climate incubator (HP1000GS-D, Ruihua Instrument & Equipment, Wuhan, China) under constant temperature (18 °C) and irradiance (150 μmol photons m−2 s−1, cool white fluorescent tubes) of 12:12 light/dark cycle (8 a.m. to 8 p.m.), and were continuously aerated for 2 days before the experiment. Sterile seawater (salinity ~ 32‰, pH ~ 8.2) enriched with 200 μM NaNO3 and 50 μM Na2HPO4 was used as culture media as our previous study (Chen and Zou 2014).

Healthy thalli of P. haitanensis were quadrated by surgical scissors (about 35 mm × 35 mm). About 0.8 g (fresh weight, Fw) samples were randomly chose to culture in 2-L conical flask with 1.5-L culture media for 1 week, and media was renewed every 2 days. The pH of culture media was calibrated with 1 M HCl and 1 M NaOH solution, to maintain constant pH level of ~ 8.2, during each culture media renewal period. Two levels of CO2, 410 ppm (ambient CO2, AC) and 1100 ppm (high CO2, HC), were controlled by aerating ambient air and intelligent incubator, respectively. Three concentrations of Cd2+ (LCd, control; MCd, 4 mg L−1; HCd, 12 mg L−1) were prepared with CdCl2. Other conditions were retained as the conditions in preculture and three replicates were done for each treatment.

Growth measurement

The growth of P. haitanensis was determined as relative growth rate (RGR): RGR = (InWt − InW0)/t × 100, where W0 was the initial Fw, while Wt was the Fw after t days (Hunt 1982). Before weighing, seawater was softly removed from the surface of P. haitanensis by blotting paper. The inhibition percentage of Cd2+ on RGR was calculated as follows: inhibition % = (RCRL − RCRt)/RCRL × 100, where RCRL is the RGR at AC-LCd, and RCRt is the RGR at MCd and HCd treatments (Gao et al. 2016).

Chlorophyll fluorescence measurement

The rapid light curves (RLCs) were generated by a pulse amplitude-modulated fluorometer (Junior PAM, Walz, Germany). RLCs were plots of electron transport rate (ETR) versus actinic irradiances (I: 0, 125, 190, 285, 420, 625, 820, 1150, and 1500 μmol photons m−2 s−1) applied for 10 s. ETR was calculated from chlorophyll fluorescence parameters automatically, ETR = Fv’/Fm’ × 0.5 × PFD, where Fv’/Fm’ is the effective PSII quantum yield and PFD is the photosynthetically active photon flux density. Efficiency of electron transport (α) and minimum saturating irradiance (Ik) were obtained from ETR = ETRmax × tanh(α × I/ETRmax) and Ik = ETRmax/α (Henley 1993).

Measurement of photosynthetic oxygen evolution

P. haitanensis was cut into 5~6-mm square and resumed in original culture media. Approximately 0.05 g (Fw) of algae (randomly chose) was placed in a transparent chamber filled with 15-mL original culture media. The chamber was sealed with a plug which a needle-type oxygen sensor (OXR50, PyroScience, Germany) was connected with, and a temperature controller (Cole-Parmer Polystat, USA) was used to ensure the whole process was proceeded at 18 °C. The net photosynthetic oxygen evolution rate (NPR) was determined under different irradiances (0, 30, 60, 100, 300, 500, and 700 μmol photons m−2 s−1, measured by a quantum sensor, SKP 200; ELE International, Leighton Buzzard, UK) supplied by a halogen lamp. The maximum photosynthetic oxygen evolution rate (NPRm) was obtained from NPR = NPRm × tanh(α × I/NPRm) + c (Henley 1993). The inhibition percentage of Cd2+ on NPRm was calculated as follows: inhibition % = (NPRL − NPRt)/NPRL × 100, where NPRL is the NPR at AC-LCd, and NPRt is the NPRm at MCd and HCd (Gao et al. 2016).

Measurement of SOD activity

For superoxide dismutase (SOD) activity, approximately 0.1 g (Fw) of P. haitanensis (randomly chose) was ground and incubated in 9 mL 0.1 M phosphate buffer (pH 7.0, containing 0.3% Triton X-100 and 4% PVPP) at 4 °C for 5 min (Neto et al. 2006). This extract was centrifuged (CT14RD, Techcomp, Shanghai, China) at 10,000 rpm, 4 °C for 10 min, and then, 30 μL of the supernatant was used to determine the SOD activity by SOD assay kit (A001-1-1, Nanjing Jiancheng Bioengineering Institute, China). The unit of SOD activity was expressed as U g−1 Fw.

Photosynthetic pigments

Chlorophyll a and carotenoids

According to Wellburn (1994), approximately 0.05 g (Fw) of algae (randomly chose) was suspended by 8 mL 100% methanol at 4 °C for 24 h avoiding light. The extract was centrifuged at 10,000 rpm, 4 °C for 5 min. The absorbance values (A) of supernatant were determined by a UV spectrophotometer (UV-1800, Shimadzu, Japan) and the contents of chlorophyll a (Chl a) and carotenoid (Car) were calculated by

Chl a = (16.72A665.2 − 9.16A652.4) × 8/0.05 and Car = (4.53A470 − 16.26A652.4 − 7.38A665.2) × 8/0.05, mg g−1 Fw.

Phycoerythrin and phycocyanin

Approximately 0.08 g (Fw) of P. haitanensis was ground and incubated in 8 mL 0.1 M phosphate buffer (pH 6.8) at 4 °C, and then centrifuged at 10,000 rpm, 4 °C for 15 min. The content of phycoerythrin (PE) and phycocyanin (PC) were estimated according to Beer and Eshel (1985): PE = [(A564 − A592) − 0.20(A455 − A592)] × 0.12 × 8/0.08 and PC = [(A618 − A645) − 0.15(A592 − A645)] × 0.15 × 8/0.08, mg g−1 Fw.

Statistical analysis

Results were expressed as means of replicates ± standard deviation. One-way analysis of variance (ANOVA) was used to analyze the effects of Cd2+ and CO2 on RGR, SOD, Chl a, Car, PE, PC, ETRmax, α, Ik, and NPRm. Significant differences among the Cd2+ concentrations at the same CO2 levels were classified after post hoc comparison test (least significant difference test), while t tests were used to calculate the significant differences between the Cd2+ pollution alone or combined with elevated CO2 and the control. A P value of 0.05 was considered statistically significant. Statistical analyses were done using SPSS v.25 (IBM, USA).



The growth of Pyropia haitanensis thalli remained positive in each culture (Fig. 1). Cd2+ treatments significantly inhibited the RGRs of P. haitanensis under ambient CO2 (AC-MCd vs. control: t = 4.377, P < 0.05; AC-HCd vs. control: t = 3.648, P < 0.05), while elevated CO2 (1100 ppm) had no significant effects on growth (HC-LCd vs. control: t = − 0.928, P > 0.05). The inhibition percentage of Cd2+ on growth was significantly decreased from 40.14 ± 6.64% in AC-grown algae to 18.38 ± 12.19% in HC-grown algae at MCd (t = 2.886, P < 0.05), and was reduced from 51.51 ± 25.11% in AC-grown algae to 23.53 ± 14.31% in HC-grown algae at HCd (t = 2.025, P > 0.05). This result indicated that compared to AC (410 ppm), HC (1100 ppm) alleviated the suppression of Cd2+ on growth of P. haitanensis.
Fig. 1

Relative growth rate (a) and inhibition percentage of Cd2+ (b) on Pyropia haitanensis cultured at different Cd2+ and CO2 conditions. Cadmium concentration: LCd, control; MCd, 4 mg L−1; HCd, 12 mg L−1. Carbon dioxide concentration: AC, 410 ppm; HC, 1100 ppm. The error bars indicate the standard deviations, n = 3. Horizontal lines represent the significant difference (P < 0.05) among the Cd2+ concentrations at the same CO2 level. Different letters represent the significant difference (P < 0.05) among the CO2 levels at the same Cd2+ concentration

Chlorophyll fluorescence

Figure 2 illustrates rapid light curves of P. haitanensis grown at different treatments, and fluorescence parameters of α, ETRmax, and Ik could be obtained from the curves (Table 1). Both CO2 and Cd2+ had no main effects on ETRmax (t = 1.226, P > 0.05; F2,12 = 0.179, P > 0.05), and according to post hoc LSD comparison, no significant difference was found between values of ETRmax measured at different Cd2+ levels in both AC- and HC-grown algae (P > 0.05; Table 1). Ik in AC-grown algae were significantly reduced upon exposure of Cd2+ (F2,12 = 5.920, P = 0.016), but the equivalent concentrations of Cd2+ had no discernible effect on Ik in HC-grown algae (F2,12 = 2.470, P > 0.05). Under the same Cd2+ level, no significant difference of Ik was observed between AC and HC-grown thalli (P > 0.05) (Table 1). Contrary to Ik, Cd2+ did not alter the values of α in AC-grown algae (F2,12 = 3.024, P > 0.05). However, α significantly rose in elevated CO2 condition (1100 ppm) (HC-LCd vs. control: t = 7.199, P < 0.01). HC-grown algae displayed a higher α value than that of AC-grown algae at HCd (t = 1.550, P > 0.05) (Table 1).
Fig. 2

The rapid light curves of Pyropia haitanensis cultured at different Cd2+ and CO2 conditions. Cadmium concentration: LCd, control; MCd, 4 mg L−1; HCd, 12 mg L−1. Carbon dioxide concentration: AC, 410 ppm; HC, 1100 ppm. The error bars indicate the standard deviations, n = 3

Table 1

The maximum electron transport rate (ETRmax), saturation irradiance (Ik), and electron transport efficiency (α) of Pyropia haitanensis cultured at different Cd2+ and CO2 conditions










129.63 ± 25.70a

125.39 ± 56.13a

116.89 ± 29.15a

116.18 ± 13.50a

112.48 ± 19.86a

109.48 ± 20.02a


0.1096 ± 0.0032b

0.1141 ± 0.0055a

0.1177 ± 0.0089a

0.1354 ± 0.0090a

0.1105 ± 0.0088a*

0.1274 ± 0.0163a


1145.70 ± 215.86a

893.97 ± 159.35a*

798.28 ± 25.88a*

947.08 ± 161.65a

1055.02 ± 66.98a

790.03 ± 193.78a

Cadmium concentration: LCd, control; MCd, 4 mg L−1; HCd, 12 mg L−1. Carbon dioxide concentration: AC, 410 ppm; HC, 1100 ppm. Different letters represent the significant difference among CO2 levels at the same Cd2+ concentration

*Significant difference among Cd2+ concentrations at the same CO2 level (the least significant difference, P < 0.05)

Net photosynthetic oxygen evolution

Cd2+ displayed outstanding negative effect on NPRm (F2,12 = 18.381, P < 0.01) of P. haitanensis. In addition, elevated CO2 significantly enhanced the values of NPRm of P. haitanensis (F1,12 = 79.630, P < 0.01). As shown in Fig. 3a, HC-grown algae exhibited higher NPRm values than AC-grown algae at two Cd2+ levels (MCd: t = 7.924, P = 0.01; HCd: t = 4.320, P = 0.012). Meanwhile, there was no significant difference between NPRm values of HC-HCd and control (t = 0.524, P = 0.628). Similar results could be drawn from Fig. 3b. The inhibition extents of Cd2+ on NPRm of HC-grown P. haitanensis were dramatically lower than that of AC-grown algae (P < 0.05). Elevated CO2 in culture significantly stimulated NPRm at all Cd2+ levels.
Fig. 3

The maximum net photosynthetic rate, NPRm (a) and inhibition percentage of Cd2+ (b) on Pyropia haitanensis cultured at different Cd2+ and CO2 conditions. Cadmium concentration: LCd, 0 mg L−1; MCd, 4 mg L−1; HCd, 12 mg L−1. Carbon dioxide concentration: AC, 410 ppm; HC, 1100 ppm. The error bars indicate the standard deviations, n = 3. Horizontal lines represent the significant difference (P < 0.05) among the Cd2+ concentrations at the same CO2 level. Different letters represent the significant difference (P < 0.05) among the CO2 levels at the same Cd2+ concentration

SOD activity

Cd2+ suppressed the SOD activity of AC-grown P. haitanensis (F2,6 = 6.539, P < 0.05). As shown in Fig. 4, SOD activity of AC-grown P. haitanensis slightly increased at MCd (P > 0.05) but was drastically lowered at HCd (P < 0.05). Elevated CO2 showed a positive effect on SOD activity of algae (HC-LCd vs. control: t = 3.478, P < 0.025). At both Cd2+ levels, HC-grown algae had higher SOD activity than AC-grown thalli (Fig. 4) (MCd: t = 3.547, P < 0.05; HCd: t = 4.692, P < 0.01). Compared to control, the SOD activity of algae grown at HC-HCd had no significant difference (t = 1.814, P > 0.144).
Fig. 4

Superoxide dismutase (SOD) activity on Pyropia haitanensis cultured at different Cd2+ and CO2 conditions. Cadmium concentration: LCd, control; MCd, 4 mg L−1; HCd, 12 mg L−1. Carbon dioxide concentration: AC, 410 ppm; HC, 1100 ppm. The error bars indicate the standard deviations, n = 3. Horizontal lines represent the significant difference (P < 0.05) among the Cd2+ concentrations at the same CO2 level. Different letters represent the significant difference (P < 0.05) among the CO2 levels at the same Cd2+ concentration

Photosynthetic pigments

In AC treatment, no significant differences of the contents of Chl a (F2,6 = 0.010, P > 0.05) and Car (F2,6 = 1.068, P > 0.05) among the different Cd2+ treatments. Elevated CO2 significantly decreased the contents of Chl a at LCd (t = − 3.602, P < 0.05) and MCd (t = − 3.537, P < 0.05), but at HCd, it had no obvious effect on Chl a contents (HC-HCd vs. control: t = 1.519, P > 0.05). However, elevated CO2 concentration did not show effect on Car content of algae at LCd (t = − 2.539, P > 0.064). Car contents of HC-HCd were increased significantly compared to the pigment’s concentration of control (t = 3.657, P < 0.05).

As shown in Fig. 5c, 12 mg L−1 Cd2+ treatment obviously decreased (t = 2.850, P < 0.05) the PE contents, but all Cd2+ concentrations had no significant effects (F2,6 = 2.725, P > 0.05) on PC contents, in AC-grown P. haitanensis. No significant changes (P < 0.05) of PE and PC contents were observed as cause of increased CO2 at all Cd2+ levels (Fig. 5c, d).
Fig. 5

Chlorophylls a (a), carotenoids (b), phycoerythrin (c), and phycocyanin (d) on Pyropia haitanensis cultured at different Cd2+ and CO2 conditions. Cadmium concentration: LCd, control; MCd, 4 mg L−1; HCd, 12 mg L−1. Carbon dioxide concentration: AC, 410 ppm; HC, 1100 ppm. The error bars indicate the standard deviations, n = 3. Horizontal lines represent the significant difference (P < 0.05) among the Cd2+ concentrations at the same CO2 level. Different letters represent the significant difference (P < 0.05) among the CO2 levels at the same Cd2+ concentration


The effect of cadmium on P. haitanensis

Coastal waters are mostly impacted by anthropogenic pollutants such as heavy metals. Being major primary producers and playing an important role in food chains in coastal waters, marine macroalgae are now being paid greater attention to the toxic effects of heavy metals such as cadmium. In the present study, 12 mg L−1 Cd2+ exerted a significant inhibition on the growth of P. haitanensis over our experiment period. Such significant suppression of growth by Cd2+ was also reported in the same algal species, P. haitanensis and Hizikia fusiformis previously (Zhu et al. 2011, 2017). A possible physiological reason for Cd2+ stress on growth might be the oxidative stress induced by cadmium exposure, as suggested by Kumar et al. (2010). It has been proved that Cd2+ induces oxidative stress like lipid peroxidation and H2O2 production in marine alga Nannochloropsis oculata (Mi and Shin 2003). SOD is an important antioxidant enzyme that can reduce oxidative stress; thereby, it plays a critical role in resisting cadmium stress (Fabrizio et al. 2003). In this study, 4 mg L−1 Cd2+ slightly increased SOD activity of P. haitanensis, while 12 mg L−1 Cd2+could dramatically reduce it. It means that the antioxidant ability was suppressed by high concentration of Cd2+. Similar results were also found in Chlorella vulgaris (a freshwater alga), in which SOD activity was increased by lower concentration of 0.5 mg L−1 Cd2+, but was dramatically decreased with higher concentration of 5 mg L−1 Cd2+ (Cheng et al. 2016).

No obvious changes were observed on contents of Chl a and Car in this experiment, even though previous studies exhibited that 10 mg L−1 Cd2+ could significantly inhibit Chl a and 8 mg L−1 Cd2+ could dramatically decrease Car of P. haitanensis (Zhu et al. 2017). The content of PE was significantly decreased by the highest concentration of Cd2+. These results displayed that the sensitivity of PE to Cd2+ were much higher than that of Chl a and Car, as the previous report (Xia et al. 2004). PE and PC are important accessory pigments, and PE is the highest content of pigment in red alga (Baghel et al. 2014), so that Cd2+ suppressed light absorption of P. haitanensis, although there was no corresponding reduction in PC. Our results showed that the maximum net photosynthetic rate NPRm and minimum saturating irradiance (Ik) of P. haitanensis were inhibited upon exposure to high level of Cd2+, even though ETRmax and α did not show significant changes that resulted from Cd2+. It has been suggested that Cd2+ may substitute Mg2+ as the central atom of chlorophyll, which thereby prevents photosynthetic light-harvesting and finally results in suppression of photosynthesis (Küpper et al. 2002). It might be the physiological reason why the content of Chl a did not decrease, but photosynthesis was negatively affected in P. haitanensis. Collectively, the present results showed that Cd2+ in high concentration (12 mg L−1) caused strong disturbance in the photosynthesis of P. haitanensis and induced oxidative stress. As a result, the thalli of P. haitanensis spent more energy on synthesizing metal-chelating proteins and peptides which reduce the bioavailability of Cd2+ to maintain cell viability (Moenne et al. 2016), making less energy available for growth.

Elevated CO2 alleviated the Cd2+ stress on P. haitanensis

Although the growth of P. haitanensis was not significantly promoted by HC (1100 ppm) at all Cd2+ levels, the inhibition of Cd2+ on growth was much less pronounced by HC (1100 ppm) in this study. Previous research showed that Cd2+ might replace the role of zinc in carbonic anhydrase to convert HCO3 into CO2 (de Baar et al. 2017), and Cd2+ in low concentration could enhance the utilization of HCO3 and CO2 in Ulca pertusa, making decrease of HCO3 and CO2 in seawater (Zheng et al. 2009). In addition, the decrease in pH induced by elevated CO2 would result in a raise in the concentrations of both HCO3 and CO2 in seawater (Feely et al. 2009). Cd2+ in low concentration and increased CO2 might have a synergistic effect on promoting growth of P. haitanensis. At the same time, the SOD activities of HC-grown algae (1100 ppm) were markedly higher than that of AC-grown algae (410 ppm) at all Cd2+ concentrations, and the inhibitory effect of Cd2+ on SOD activity was decreased in HC-grown algae, which means that 1100 ppm CO2 dramatically enhanced SOD activity of P. haitanensis. Moreover, SOD activity of algae grown in 1100 ppm was not inhibited at 12 mg L−1 Cd2+ compared to other Cd2+ levels, indicating that increased CO2 enhanced the antioxidant ability of P. haitanensis. Similar results were reported in Ginkgo biloba (Ruan et al. 2007) and Cocosnucifera L. (Sunoj et al. 2014), of which the SOD activities were dramatically increased by short-term CO2 elevation.

In present study, the contents of Chl a and Car in HC-grown algae (1100 ppm) decreased significantly at control and 4 mg L−1 Cd2+ compared to that in AC-grown algae (410 ppm). The content of Chl a in Porphyra leucosticte (Rhodophyta) was also reduced by elevated CO2 (Mercado et al. 1999). Such inhibition was likely due to the accumulation of excess polysaccharide which affected the normal structure and function of chloroplasts (Cave et al. 1981). However, the algae grown in HC-HCd (1100 ppm, 12 mg L−1 Cd2+) had similar contents of Chl a and Car with the one grown in AC-LCd (410 ppm, control). The increase of Chl a might be attributed to the synthesis of chlorophyll-Cd2+ (Küpper et al. 2002), and promotion of Car might result from the stress response to Cd2+ which enhanced the antioxidant ability of P. haitanensis (Strzałka et al. 2003).

Ik and ETRmax had no obvious changes at all Cd2+ levels in high CO2 concentration, but the efficiency of electron transport, α increased significantly at LCd by elevated CO2. A possible explanation is that P. haitanensis may improve the utilization efficiency of solar energy to offset the low contents of photosynthesis pigments in high CO2 environment. The notable higher NPRm in HC-grown algae also confirms this conjecture. The elevated CO2 might inhibit the photorespiration process and reduce oxygen fixation (Peterhansel et al. 2010), increasing NPRm in HC-grown algae. This can be supported by the fact that NPRm of Porphyra leucosticte (Mercado et al. 1999) and U. Prolifera (Gao et al. 2016) were increased in high CO2 level.

The defense against Cd2+ is energy-intensive. When the excess Cd2+ break through the cell membrane, phytochelatin (PCs) are produced to combined with Cd2+, and then, these Cd2+ chelates are wrapped to many small vesicles (Andrade et al. 2010; Talarico 2002). In addition, the synthetics of SOD enzyme and chlorophyll-Cd2+ are the energy-costing processes. Therefore, more energy would be used to maintain essential metabolism and cellular integrity, resulting in less energy for growth. Excess polysaccharide synthesized in high CO2 concentration might be a sufficient energy source (Andrade et al. 2010), so that the inhibition of Cd2+ on growth and antioxidant ability of HC-grown P. haitanensis were decreased in this research. In addition, the inhibitory effect of Cd2+ on NPRm of algal thalli was decreased by elevated CO2.

Collectively, the present study showed that high CO2 concentration (1100 ppm) reduced the toxicity of Cd2+ on the alga. We suggested that the predicted high CO2 level in the future might be in favor of P. haitanensis aquaculture when facing with the aggravation of marine cadmium pollution. Further studies are needed to address the time course of physiological characteristics and the underlying molecular mechanisms with the combined effects of future anthropogenic CO2 and heavy metal pollution.



This study was supported by the National Natural Science Foundation of China (Grant Nos. 31741018 and 41706136) and Guangdong Province (Grant No. 2018B030311029).


  1. Andrade LR, Leal RN, Noseda M, Duarte ME, Pereira MS, Mourão PA, Farina M, Amado Filho GM (2010) Brown algae overproduce cell wall polysaccharides as a protection mechanism against the heavy metal toxicity. Mar Pollut Bull 60:1482–1488CrossRefGoogle Scholar
  2. Babu MY, Palanikumar L, Nagarani N, Devi VJ, Kumar SR, Ramakritinan CM, Kumaraguru AK (2014) Cadmium and copper toxicity in three marine macroalgae: evaluation of the biochemical responses and DNA damage. Environ Sci Pollut Res Int 21:9604–9616CrossRefGoogle Scholar
  3. Baghel RS, Kumari P, Reddy CRK, Jha B (2014) Growth, pigments, and biochemical composition of marine red alga Gracilaria crassa. J Appl Phycol 26:2143–2150CrossRefGoogle Scholar
  4. Bedir S, Yilmaz VM (2016) CO2 emissions and human development in OECD countries: granger causality analysis with a panel data approach. Eur Econ Rev 6:97–110CrossRefGoogle Scholar
  5. Beer S, Eshel A (1985) Determining phycoerythrin and phycocyanin concentrations in aqueous crude extracts of red algae. Mar Freshw Res 36:785–792CrossRefGoogle Scholar
  6. Bouzon ZL, Ferreira EC, Dos SR, Scherner F, Horta PA, Maraschin M, Schmidt EC (2012) Influences of cadmium on fine structure and metabolism of Hypnea musciformis (Rhodophyta, Gigartinales) cultivated in vitro. Protoplasma 249:637–650CrossRefGoogle Scholar
  7. Cave G, Tolley LC, Strain BR (1981) Effect of carbon dioxide enrichment on chlorophyll content, starch content and starch grain structure in Trifolium subterraneum leaves. Physiol Plant 51:171–174CrossRefGoogle Scholar
  8. Chen B, Zou D (2014) Growth and photosynthetic activity of Sargassum henslowianum (Fucales, Phaeophyta) seedlings in responses to different light intensities, temperatures and CO2 levels under laboratory conditions. Mar Biol Res 10:1019–1026CrossRefGoogle Scholar
  9. Chen M, Xu J, Pan Q, Gao X (2011) Analysis of nutritional composition and polysaccharide composition in low-value Porphyra haitanensis. Food Sci 32:230–234Google Scholar
  10. Cheng J, Qiu H, Chang Z, Jiang Z, Yin W (2016) The effect of cadmium on the growth and antioxidant response for freshwater algae Chlorella vulgaris. SpringerPlus 5:1290CrossRefGoogle Scholar
  11. Chung IK, Kang YH, Yarish C, Kraemer GP, Lee JA (2002) Application of seaweed cultivation to the bioremediation of nutrient-rich effluent. Algae 17:187–194CrossRefGoogle Scholar
  12. Chung IK, Beardall J, Mehta S, Sahoo D, Stojkovic S (2011) Using marine macroalgae for carbon sequestration: a critical appraisal. J Appl Phycol 23:877–886CrossRefGoogle Scholar
  13. de Baar HJW, van Heuven SMAC, Abouchami W, Xue Z, Galer SJG, Rehkämper M, Middag R, van Ooijen J (2017) Interactions of dissolved CO2 with cadmium isotopes in the Southern Ocean. Mar Chem 195:105–121CrossRefGoogle Scholar
  14. Evans RD, Wilson SK, Field SN, Moore JAY (2014) Importance of macroalgal fields as coral reef fish nursery habitat in north-west Australia. Mar Biol 161:599–607CrossRefGoogle Scholar
  15. Fabrizio P, Lannelli MA, Pasqualini S, Massacci A (2003) Interaction of cadmium with glutathione and photosynthesis in developing leaves and chloroplasts of Phragmites australis (Cav.) Trin. ex Steudel. Plant Physiol 133:829–837CrossRefGoogle Scholar
  16. Fabry VJ, Seibel BA, Feely RA, Orr JC (2008) Impacts of ocean acidification on marine fauna and ecosystem processes. ICES J Mar Sci 65:414–432CrossRefGoogle Scholar
  17. Feely RA, Doney SC, Cooley SR (2009) Ocean acidification: present conditions and future changes in a high-CO2 world. Oceanography 22:36–47CrossRefGoogle Scholar
  18. Gao G, Liu Y, Li X, Feng Z, Xu Z, Wu H, Xu J (2016) Expected CO2-induced ocean acidification modulates copper toxicity in the green tide alga Ulva prolifera. Environ Exp Bot 135:63–72CrossRefGoogle Scholar
  19. Henley WJ (1993) Measurement and interpretation of photosynthesis light-response curves in algae in the context of photoinhibition and diel changes. J Phycol 29:729–739CrossRefGoogle Scholar
  20. Hunt R (1982) Plant growth curves: the functional approach to plant growth analysis. Edward Arnold Ltd., LondonGoogle Scholar
  21. Jiang H, Gao B, Li W, Zhu M, Zheng C, Zheng Q, Wang C (2013) Physiological and biochemical responses of Ulva prolifera and Ulva linza to cadmium stress. Sci World J 2013:11Google Scholar
  22. Kuffner IB, Andersson AJ, Jokiel PL, Rodgers KUS, Mackenzie FT (2008) Decreased abundance of crustose coralline algae due to ocean acidification. Nat Geosci 1:114–117CrossRefGoogle Scholar
  23. Kumar M, Kumari P, Gupta V, Anisha PA, Reddy CR, Jha B (2010) Differential responses to cadmium induced oxidative stress in marine macroalga Ulva lactuca (Ulvales, Chlorophyta). Biometals 23:315–325CrossRefGoogle Scholar
  24. Küpper H, Šetlk I, Spiller M, Küpper FC, Prášil O (2002) Heavy metal-induced inhibition of photosynthesis: targets of in vivo heavy metal chlorophyll formation. J Phycol 38:429–441CrossRefGoogle Scholar
  25. Li Y, Guo L, Feng H (2015) Status and trends of sediment metal pollution in Bohai Sea, China. Curr Pollu Rep 1:191–202CrossRefGoogle Scholar
  26. Liu G (2017) Small pyropia and big industry. Shantou daily (in Chinese), Shantou, ChinaGoogle Scholar
  27. Mercado JM, Javier F, Gordillo L, Niell FX, Figueroa FL (1999) Effects of different levels of CO2 on photosynthesis and cell components of the red alga Porphyra leucosticta. J Appl Phycol 11:455–461CrossRefGoogle Scholar
  28. Mi YL, Shin HW (2003) Cadmium-induced changes in antioxidant enzymes from the marine alga Nannochloropsis oculata. J Appl Phycol 15:13–19CrossRefGoogle Scholar
  29. Millero FJ, Woosley R, Ditrolio B, Waters J (2009) Effect of ocean acidification on the speciation of metals in seawater. Oceanography 22:72–85CrossRefGoogle Scholar
  30. Moenne A, González A, Sáez CA (2016) Mechanisms of metal tolerance in marine macroalgae, with emphasis on copper tolerance in Chlorophyta and Rhodophyta. Aquat Toxicol 176:30–37CrossRefGoogle Scholar
  31. Naser HA (2013) Assessment and management of heavy metal pollution in the marine environment of the Arabian Gulf: a review. Mar Pollut Bull 72:6–13CrossRefGoogle Scholar
  32. Neto ADDA, Prisco JT, Enéas-Filho J, Abreu CEBD, Gomes-Filho E (2006) Effect of salt stress on antioxidative enzymes and lipid peroxidation in leaves and roots of salt-tolerant and salt-sensitive maize genotypes. Environ Exp Bot 56:87–94CrossRefGoogle Scholar
  33. Peterhansel C, Horst I, Niessen M, Blume C, Kebeish R, Kürkcüoglu S, Kreuzaler F (2010) Photorespiration. Arabidopsis Book 8:e0130CrossRefGoogle Scholar
  34. Price NN, Hamilton SL, Tootell JS, Smith JE (2011) Species-specific consequences of ocean acidification for the calcareous tropical green algae Halimeda. Mar Ecol Prog Ser 440:67–78CrossRefGoogle Scholar
  35. Qiao Y, Yang Y, Gu J, Zhao J (2013) Distribution and geochemical speciation of heavy metals in sediments from coastal area suffered rapid urbanization, a case study of Shantou Bay, China. Mar Pollut Bull 68:140–146CrossRefGoogle Scholar
  36. Ragazzola F, Foster LC, Form A, Anderson PS, Hansteen TH, Fietzke J (2012) Ocean acidification weakens the structural integrity of coralline algae. Glob Chang Biol 18:2804–2812CrossRefGoogle Scholar
  37. Ranjbar Jafarabadi A, Riyahi Bakhtiyari A, Shadmehri Toosi A, Jadot C (2017) Spatial distribution, ecological and health risk assessment of heavy metals in marine surface sediments and coastal seawaters of fringing coral reefs of the Persian Gulf, Iran. Chemosphere 185:1090–1111CrossRefGoogle Scholar
  38. Ruan Y, He X, Chen W, Xu S, Xu W (2007) Effects of elevated CO2 on lipid peroxidation and activities of antioxidant enzymes in Ginkgo biloba. Acta Ecol Sin 27:1106–1112Google Scholar
  39. Rubinelli P, Siripornadulsil S, Gao-Rubinelli F, Sayre RT (2002) Cadmium- and iron-stress-inducible gene expression in the green alga Chlamydomonas reinhardtii: evidence for H43 protein function in iron assimilation. Planta 215:1–13CrossRefGoogle Scholar
  40. Strzałka K, Kostecka-Gugała A, Latowski D (2003) Carotenoids and environmental stress in plants: significance of carotenoid-mediated modulation of membrane physical properties. Russ J Plant Physiol 50:168–173CrossRefGoogle Scholar
  41. Sunoj VSJ, Kumar SN, Muralikrishna KS (2014) Effect of elevated CO2 and temperature on oxidative stress and antioxidant enzymes activity in coconut (Cocosnucifera L.) seedlings. Indian J Plant Physiol 19:382–387CrossRefGoogle Scholar
  42. Talarico L (2002) Fine structure and X-ray microanalysis of a red macrophyte cultured under cadmium stress. Environ Pollut 120:813–821CrossRefGoogle Scholar
  43. Wang SL, Xu XR, Sun YX, Liu JL, Li HB (2013) Heavy metal pollution in coastal areas of South China: a review. Mar Pollut Bull 76:7–15CrossRefGoogle Scholar
  44. Wellburn AR (1994) The spectral determination of chlorophylls a and b, as well as total carotenoids, using various solvents with spectrophotometers of different resolution. J Plant Physiol 144:307–313CrossRefGoogle Scholar
  45. Xia JR, Li YJ, Lu J, Chen B (2004) Effects of copper and cadmium on growth, photosynthesis, and pigment content in Gracilaria lemaneiformis. Bull Environ Contam Toxicol 73:979–986CrossRefGoogle Scholar
  46. Xu K, Chen H, Wang W, Xu Y, Ji D, Chen C, Xie C (2017) Responses of photosynthesis and CO2 concentrating mechanisms of marine crop Pyropia haitanensis thalli to large pH variations at different time scales. Algal Res 28:200–210CrossRefGoogle Scholar
  47. Yang Y, Chai Z, Wang Q, Chen W, He Z, Jiang S (2015) Cultivation of seaweed Gracilaria in Chinese coastal waters and its contribution to environmental improvements. Algal Res 9:236–244CrossRefGoogle Scholar
  48. Zhang Z, Zhang Q, Wang J, Song H, Zhang H, Niu X (2010) Regioselective syntheses of sulfated porphyrans from Porphyra haitanensis and their antioxidant and anticoagulant activities in vitro. Carbohydr Polym 79:1124–1129CrossRefGoogle Scholar
  49. Zheng G, Song J, Wei J, Cheng L, Yuan H (2009) Effects of heavy metal (copper, cadmium, zinc and lead) on marine inorganic carbon system in simulated experiments. Acta Ecol Sin 29:3009–3018Google Scholar
  50. Zhu X, Zou D, Du H (2011) Physiological responses of Hizikia fusiformis to copper and cadmium exposure : Botanica Marina. Bot Mar 54:431–439Google Scholar
  51. Zhu X, Zou D, Huang Y, Cao J, Sun Y, Chen B, Chen X (2017) Physiological responses of Porphyra haitanensis (Rhodophyta) to copper and cadmium exposure. Bot Mar 60:27–37CrossRefGoogle Scholar
  52. Zou D, Gao K (2002) Effects of elevated CO2 concentration on the photosynthesis and related physiological processes in marine macroalgae. Acta Ecol Sin 22:1750–1757Google Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Haiying Ma
    • 1
  • Dinghui Zou
    • 1
    • 2
    Email author
  • Jiayi Wen
    • 1
  • Zhiwei Ji
    • 1
  • Jingyu Gong
    • 1
  • Chunxiang Liu
    • 3
  1. 1.School of Environment and EnergySouth China University of TechnologyGuangzhouChina
  2. 2.Key Laboratory of Atmospheric Environment and Pollution ControlSouth China University of TechnologyGuangzhouChina
  3. 3.College of life SciencesHuaibei Normal UniversityHuaibeiChina

Personalised recommendations