Publication Date:
2024-03-15
Description:
Coral reefs worldwide are affected by increasing dissolved inorganic carbon (DIC) and organic carbon (DOC) concentrations due to ocean acidification (OA) and coastal eutrophication. These two stressors can occur simultaneously, particularly in near-shore reef environments with increasing anthropogenic pressure. However, experimental studies on how elevated DIC and DOC interact are scarce and fundamental to understanding potential synergistic effects and foreseeing future changes in coral reef function. Using an open mesocosm experiment, the present study investigated the impact of elevated DIC (pHNBS: 8.2 and 7.8; pCO2: 377 and 1076 µatm) and DOC (added as 833 µmol/L of glucose) on calcification and photosynthesis rates of two common calcifying green algae, Halimeda incrassata and Udotea flabellum, in a shallow reef environment. Our results revealed that under elevated DIC, algal photosynthesis decreased similarly for both species, but calcification was more affected in H. incrassata, which also showed carbonate dissolution rates. Elevated DOC reduced photosynthesis and calcification rates in H. incrassata, while in U. flabellum photosynthesis was unaffected and thalus calcification was severely impaired. The combined treatment showed an antagonistic effect of elevated DIC and DOC on the photosynthesis and calcification rates of H. incrassata, and an additive effect in U. flabellum. We conclude that the dominant sand dweller H. incrassata is more negatively affected by both DIC and DOC enrichments, but that their impact could be mitigated when they occur simultaneously. In contrast, U. flabellum can be less affected in coastal eutrophic waters by elevated DIC, but its contribution to reef carbonate sediment production could be further reduced. Accordingly, while the capacity of environmental eutrophication to exacerbate the impact of OA on algal-derived carbonate sand production seems to be species-specific, significant reductions can be expected under future OA scenarios, with important consequences for beach erosion and coastal sediment dynamics.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Benthos; Bicarbonate ion; Bicarbonate ion, standard deviation; Biological oxygen demand; Biological oxygen demand, standard deviation; Calcification/Dissolution; Calcification rate, standard deviation; Calcification rate, standard error; Calcification rate of calcium carbonate; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, organic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, partial pressure, standard deviation; Chlorophyta; Coast and continental shelf; Containers and aquaria (20-1000 L or 〈 1 m**2); Date; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gross photosynthesis rate, oxygen; Gross photosynthesis rate, oxygen, standard error; Gross photosynthesis rate, standard deviation; Halimeda incrassata; Laboratory experiment; Macroalgae; Maximum photochemical quantum yield of photosystem II; Maximum photochemical quantum yield of photosystem II, standard error; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Other; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Plantae; Primary production/Photosynthesis; Puerto_Morelos__OA; Registration number of species; Respiration; Respiration rate, oxygen; Respiration rate, oxygen, standard deviation; Respiration rate, oxygen, standard error; Salinity; Salinity, standard deviation; Single species; Species; Temperature, standard deviation; Temperature, water; Time in days; Treatment; Tropical; Type; Udotea flabellum; Uniform resource locator/link to reference
Type:
Dataset
Format:
text/tab-separated-values, 3488 data points
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