Effect of nutrient enrichment and elevated CO2 partial pressure on growth rate of Atlantic scleractinian coral Acropora cervicornis

Abstract

The growth rate of Acropora cervicornis branch tips maintained in the laboratory was measured before, during, and after exposure to elevated nitrate (5 and 10 µM NO 3 -), phosphate (2 and 4 µM P-PO 4 3 ) and/or pCO 2 (CO 2~7 00 to 800 µatm). The effect of increased pCO 2 was greater than that of nutrient enrichment alone. High concentrations of nitrate or phosphate resulted in significant decreases in growth rate, in both the presence and absence of increased pCO 2 . The effect of nitrate and phosphate enrichment combined was additive or antagonistic relative to nutrient concentration and pCO 2 level. Growth rate recovery was greater after exposure to increased nutrients or CO 2 compared to increased nutrients and CO 2 . If these results accurately predict coral response in the natural environment, it is reasonable to speculate that the survival and reef-building potential of this species will be significantly negatively impacted by continued coastal nutrification and projected pCO 2 increases.KEY WORDS: Acropora cervicornis · Nutrient enrichment · pCO 2 · Growth rate Resale or republication not permitted without written consent of the publisher

Long-term effects of nutrient and CO2 enrichment on the temperate coral Astrangia poculata (Ellis and Solander, 1786)

“…Thus, the response of A. poculata to changing pCO 2 levels depends on the nutritional status of the coral holobiont, and the response to nutrients is similarly dependent upon DIC. Conversely, Renegar and Riegl (2005) found no benefit from adding nitrate or phosphate under elevated CO 2 conditions, however, in their study, DIC was lower in the high CO 2 treatment. Similarly, Marubini and Atkinson (1999) found no benefit from adding nutrients under acidified conditions, however, their acidification treatment was also associated with lower DIC.…”

“…To date, four studies have specifically addressed the interaction of nutrients and carbonate chemistry on calcification (Marubini and Atkinson, 1999;Marubini and Thake, 1999;Langdon and Atkinson, 2005;Renegar and Riegl, 2005). Both the work of Marubini and Thake (1999) and of Marubini and Atkinson (1999) looked only at nitrogen, yet other nutrients, such as P and Fe have been found to be limiting in many systems (e.g.…”

“…Jury et al, 2008). The one study to combine CO 2 and nutrients incurred high rates of coral mortality (Renegar and Riegl, 2005), which makes interpretation of calcification rates difficult.…”

A hypothesis linking sub-optimal seawater <I>p</I>CO<sub>2</sub> conditions for cnidarian-<I>Symbiodinium</I> symbioses with the exceedence of the interglacial threshold (>260 ppmv)

“…Secondly, since limited availability of DIN may restrict the underpinning turnover and loss of zooxanthellae associated with elevated pCO 2 conditions, it is consistent that reduced seawater DIN is beneficial in limiting the impact of rising pCO 2 on coral calcification (Renegar and Riegl, 2005). Finally, for nutrient-replete experimental conditions that permit an increase in the CSD of zooxanthellae, it is consistent that the most detrimental impact of elevated pCO 2 (760 ppmv) on P:R and calcification occurs when temperature is also elevated (Reynaud et al, 2003).…”

Investigating the Driving Mechanisms Behind Differences in Bleaching and Disease Susceptibility Between Two Scleractinian Corals, Pseudodiploria Strigosa and Diploria Labyrinthiformis

“…A CO2 injection system (AZOO, Taiwan) was used to infuse CO2 into experimental tanks to lower pH via the natural buffering system present in aquatic systems. This approach is based on well-described equilibrium reactions that include the following: CO2 (atm) ⇌ CO2 (aq) + H2O ⇌ H + + HCO3 -⇌ 2H + + CO3 2- (Doney et al 2009), and has been widely used to manipulate pH in experimental setups (Leclercq et al 2000, Renegar andRiegl 2005). Although the bubbling of CO2 does affect carbonate/bicarbonate chemistry as well, only pH was measured in this experiment, using an EcoTester pH2 probe (Oakton).…”