Publication Date:
2024-03-15
Description:
The effects of elevated CO2 and temperature on photosynthesis and calcification in the calcifying algae Halimeda macroloba and Halimeda cylindracea and the symbiont-bearing benthic foraminifera Marginopora vertebralis were investigated through exposure to a combination of four temperatures (28°C, 30°C, 32°C, and 34°C) and four CO2 levels (39, 61, 101, and 203 Pa; pH 8.1, 7.9, 7.7, and 7.4, respectively). Elevated CO2 caused a profound decline in photosynthetic efficiency (FV : FM), calcification, and growth in all species. After five weeks at 34°C under all CO2 levels, all species died. Chlorophyll (Chl) a and b concentration in Halimeda spp. significantly decreased in 203 Pa, 32°C and 34°C treatments, but Chl a and Chl c2 concentration in M. vertebralis was not affected by temperature alone, with significant declines in the 61, 101, and 203 Pa treatments at 28°C. Significant decreases in FV : FM in all species were found after 5 weeks of exposure to elevated CO2 (203 Pa in all temperature treatments) and temperature (32°C and 34°C in all pH treatments). The rate of oxygen production declined at 61, 101, and 203 Pa in all temperature treatments for all species. The elevated CO2 and temperature treatments greatly reduced calcification (growth and crystal size) in M. vertebralis and, to a lesser extent, in Halimeda spp. These findings indicate that 32°C and 101 Pa CO2, are the upper limits for survival of these species on Heron Island reef, and we conclude that these species will be highly vulnerable to the predicted future climate change scenarios of elevated temperature and ocean acidification.
Keywords:
Alkalinity, total; Alkalinity, total, standard error; Aragonite saturation state; Aragonite saturation state, standard deviation; Autotitrator (Mettler Toledo); Benthos; Bicarbonate ion; Bicarbonate ion, standard error; Biomass/Abundance/Elemental composition; Buoyant weighing technique according to Davies (1989); Calcification/Dissolution; Calcification rate; Calcification rate, standard error; Calcite saturation state; Calcite saturation state, standard deviation; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard error; Carbonate ion; Carbonate ion, standard error; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, partial pressure; Carbon dioxide, partial pressure, standard deviation; Carbon dioxide, standard error; Chlorophyta; Chromista; Coast and continental shelf; Containers and aquaria (20-1000 L or 〈 1 m**2); EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Experimental treatment; Fiber-optic oxygen microsensor PSt1 with MicroTX3 transmitter (Presens); Foraminifera; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Halimeda cylindracea, chlorophyll a; Halimeda cylindracea, chlorophyll a, standard error; Halimeda cylindracea, chlorophyll b; Halimeda cylindracea, chlorophyll b, standard error; Halimeda cylindracea, crystal width; Halimeda cylindracea, crystal width, standard error; Halimeda macroloba, chlorophyll a; Halimeda macroloba, chlorophyll a, standard error; Halimeda macroloba, chlorophyll b; Halimeda macroloba, chlorophyll b, standard error; Halimeda macroloba, crystal width; Halimeda macroloba, crystal width, standard error; Heterotrophic prokaryotes; Identification; Laboratory experiment; Macroalgae; Marginopora vertebralis; Marginopora vertebralis, chlorophyll a; Marginopora vertebralis, chlorophyll a, standard error; Marginopora vertebralis, chlorophyll c2; Marginopora vertebralis, chlorophyll c2, standard error; Marginopora vertebralis, crystal width; Marginopora vertebralis, crystal width, standard error; Marginopora vertebralis, symbiont cell density; Marginopora vertebralis, symbiont density, standard error; Maximum photochemical quantum yield, standard error; Maximum photochemical quantum yield of photosystem II; Measured; OA-ICC; Ocean Acidification International Coordination Centre; Oxygen production rate; Oxygen production rate, standard error; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Plantae; Primary production/Photosynthesis; Salinity; Scanning electron microscope (Zeiss Supra 55VP); see reference(s); Single species; South Pacific; Spectrophotometry; Temperature; Temperature, water; Tropical
Type:
Dataset
Format:
text/tab-separated-values, 3776 data points
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