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Acclimation of cold-water corals to ocean acidification

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Poster presented by Laura Wicks at the 3rd Symposium on Oceans in a High CO2 World, Monterey USA, Sep 2012

Poster presented by Laura Wicks at the 3rd Symposium on Oceans in a High CO2 World, Monterey USA, Sep 2012


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  • 1. Acclimation of the cold-water coral Lophelia pertusa to predicted rises in atmospheric CO2 and sea temperature UK Ocean Acidification Research Programme Wicks LC1, Hennige SJ1, Roberts JM1,2, 3 40 Introduction Results μmol O 2 g -1 tissue dry weight h - 1 58°30’0’’N 3 35 30 Short term Cold-water corals are amongst the most three-dimensionally complex deep-sea habitats known and are associated with high local 58°0’0’’N 25 Respiration biodiversity1. However, their remoteness and the relatively short history of ecological research in these habitats mean that to date, we have L. pertusa respiration rate decreased in acidified conditions (750ppm, 11.4 ± 1.39 SE, µmol O2 g-1 tissue dry weight h-1) over 21 days 20 compared to present day conditions (28.6 ± 7.30 SE µmol O2 g-1 tissue dry weight h-1), with a significant difference between treatments only little information on how these ecosystems will fare in the face of predicted future climate change. 15 being observed after 2 weeks. (Fig. 3). Projected rises in atmospheric pCO2 will reduce the oceanic pH and the availability of carbonate ions (ocean acidification, or OA), and 57°30’0’’N increased sea temperatures may perturb cold-water coral systems beyond their thermal limits. Rep. of Ireland 10 L. pertusa calcification rate (AAT) did not change in control or acidified conditions (750ppm) over 21 days (Fig. 4). Calcification rate as United determined by 14C uptake also did not differ between treatment and control fragments at either the experiment start or end (390 ppm; 1.68 x Indeed, cold-water corals are likely to be among the first affected by ocean acidification2 as they inhabit a large bathymetric range, and as Kingdom 5 Control 750 ppm Mingulay 10-2 (± SE 0.60), 750 ppm; 4.38 x 10-2 (± SE 1.6) µmol CaCO3 g-1 tissue dry weight h-1). However, there was a significant decrease in such many lie close to the aragonite saturation horizon. With OA, the ASH is predicted to become shallower, making it more difficult for Sea of the Hebrides 57°0’0’’N 0 calcification rates measured by 14C uptake in 380 ppm fragments over time, which was not significant in 750 ppm fragments, due to very T0 T7 T14 T21 calcifying organisms near this depth to maintain their calcified structures, and thus affecting net reef growth. high variability. Time point (day) Currently, the single and synergistic effects of projected increases in atmospheric pCO2 and sea temperatures upon the cold-water coral i Long term 56°30’0’’N Lophelia pertusa are unknown. Studies to date have only examined L. pertusa response to either increased temperature or increased CO2 on 4 4 short time scales3,4. However, short-term studies may not reflect L. pertusa acclimation to synergistic stressors. 7°30’0’’W 7°0’0’’W 6°30’0’’W After 3 months, respiration rate of L. pertusa was highest in the control treatment (9°C, 380 ppm, 3.5 ± 0.42 SE, µmol O2 g-1 tissue dry weight h-1), but was not significantly different from all single stressor treatments (enhanced CO2 treatments, or the increased temperature/ambient µmol CaCO3 g -1h-1 Furthermore, studies to date have focused on growth rates and ranged from very short term (24 hours4) on freshly collected coral, to Calcification rate 3 CO2 treatment, Fig. 5). The dual-stressor treatment of increased temperature and CO2 had significantly lower respiration rates (1.5 ± 0.42 SE, long-term (6 months5) experiments on laboratory-kept specimens. However, to fully understand how the impact of increased CO2 on 380 ppm µmol O2 g-1 tissue dry weight h-1) than all other treatments. CWC, it is important to combine growth rates with measures of metabolism. 2 750 ppm Growth was reduced after 3 months in the dual-stressor treatment (0.18% increase) compared to the ambient CO2 treatments (1.9-2.7%, Fig. In this study, we examined the short and long term effects of OA and warming on the calcification and metabolism of L. pertusa, to 6). Indeed, all L. pertusa in enhanced CO2 treatments showed lower growth rates than corals in ambient CO2. However, after 6 months there determine whether acclimation will occur in a future warmer, high CO2 world. 1 was no signficant difference in growth between all treatments (2.2-3.2% increase). All respiration measurements are presented normalised to tissue dry weight. It should be noted that respiration rates declined over time in all 0 aquaria-kept corals, likely due to the feeding limitations of aquaria in comparison to the in situ food supply. T0 T7 T14 T21 Time point (day) 4 μmol O2 g -1 tissue dry weight h - 1 5 Methods Fig. 1. Location of Mingulay Reef Complex with colour multibeam 3 Conclusions Sample collection bathymetry. Sample area has been circled on the multibeam map. Respiration Ocean Acidification Colonies of L. pertusa were collected from the Mingulay Reef Complex, Area 1 (56° 49.38 N, 7° 22.56 W, Fig.1), during the Discovery D366/7 UK 2 In the short term, there was a significantly negative effect of OA on L. pertusa, however partial acclimation was apparent after three months Ocean Acidification Expedition in July 2011. Colonies were collected from 141 - 167 m using a modified video assisted van-Veen grab. Upon with no signficant reduction in respiration. It may be that energetic reserves are being used to mitigate the reduced energy production by return to the surface, corals were placed in a holding tank at ambient temperature for 2 days, to recover from collection. Corals were then 1 respiration observed in the short term, however this will not be sustainable in the long term. carefully fragmented into smaller pieces for experiments. 9°C 12°C 9°C 9°C 12°C 380 ppm 380 ppm 750 ppm 1000 ppm 750 ppm Temperature Short term experiments Although there was no significant change in calcification and respiration in response to temperature, the results were highly variable. Further Coral fragments were subject to two CO2 levels for 21 days: 380 and 750 ppm. CO2 levels were achieved using pre-mixed gas bubbling into analysis will be possible after 6 and 12 month time points. chilled tanks at ambient reef temperature. Corals were fed every 2 days. Physiological measurements were taken at time zero, and after 7, 14 and 21 days. 3.5 Combined effect (most likely scenario) 6 Long-term experiments 3 Despite a significant reduction in respiration rate compared to controls after 3 months, acclimation appears to have occured after 6 months, 0-3 months when there is no signficant difference in calcification rates. Percentage mass change Upon return to HWU, coral fragments were distributed between 20 seperate OA mesocosms, with four mesocosms for each treatment. The 2.5 3-6 months treatments were: 9°C and 380 ppm, 9°C and 750 ppm, 9°C and 1000 ppm, 12°C and 380 ppm, 12°C and 750 ppm. Corals were fed 3 times per 2 Our results suggest that L. pertusa has both shock and acclimation responses to OA and warming. Indeed, the two-week period observed here week. Physiological measurements were taken at time zero, and after 3, 6 and 12 months. before any noticeable differences were observed between experimental and control fragments may indicate a switching of metabolic 1.5 pathways cued by extended exposure to elevated CO2. Physiological measurements 1 Although it appears acclimation may be possible in a future of warmer, high CO2 seas, L. pertusa will be reliant on a sustained or potentially For both experiments, metabolic rates were determined in coral fragments placed within 220 mL incubation chambers fitted with oxygen Fig. 2. Lophelia pertusa in tanks, 0.5 enhanced energetic input, of which we know little. Indeed, if calcification is sustained but at a higher energetic cost, the reallocation of energy optodes connected to a temperature-compensated oxygen analyser (Oxy-4 Mini with Temp-4, Presens & Loligo systems). Rates of respiration chambers, and with polyps 0 away from reproductive output and maintanance could have effects at the population level. calcification and growth were determined using the alkalinity anomaly technique6 (AAT) with 4 h incubations, and 14C and 45Ca for 6 h out. RRS Discovery at Mingulay. incubations. The buoyant weight technique7 was also used for the long term experiment. - 0.5 9°C 12°C 9°C 9°C 12°C 380 ppm 380 ppm 750 ppm 1000 ppm 750 ppm -1References: 1. Roberts et al. (2006) Science 312: 543-547; 2. Guinotte et al. (2006) Front Ecol Environ 4:141–146; 3. Dodds et al. (2007) MEPS Acknowledgements: UK Ocean Acidification Research Programme (Natural Environment Research 1: Centre for Marine Biodiversity and Biotechnology, Heriot-Watt University, Edinburgh, EH14 4AS, UK397:113-124; 4. Maier et al. (2009) Biogeosciences 6(8):1671-1680; 5. Form & Riebesell (2012) Glob Change Biol 18:843-853; 6. EPOCA Best Council grant NE/H017305/1) and the European Commission’s Seventh Framework Programme 2: Center for Marine Science, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403-5928, USAPractices Guide (2011); 7. Davies (1989) 101:389-395 (FP7/2007-2013) project EPOCA (grant agreement n° 211384). Juan Moreno-Navas, Kim Last (SAMS), 3: Scottish Association for Marine Science, Scottish Marine Institute, Oban, Argyll, PA37 IQA, UK participants on Discovery Cruise D366/7, Solvin Zankl for images.