Publication Date:
2024-03-15
Description:
Ocean acidification (OA), caused by the dissolution of increasing concentrations of atmospheric carbon dioxide (CO2) in seawater, is projected to cause significant changes to marine ecology and biogeochemistry. Potential impacts on the microbially driven cycling of nitrogen are of particular concern. Specifically, under seawater pH levels approximating future OA scenarios, rates of ammonia oxidation (the rate-limiting first step of the nitrification pathway) have been shown to dramatically decrease in seawater, but not in underlying sediments. However, no prior study has considered the interactive effects of microbial ammonia oxidation and macrofaunal bioturbation activity, which can enhance nitrogen transformation rates. Using experimental mesocosms, we investigated the responses to OA of ammonia oxidizing microorganisms inhabiting surface sediments and sediments within burrow walls of the mud shrimp Upogebia deltaura. Seawater was acidified to one of four target pH values (pHT 7.90, 7.70, 7.35 and 6.80) in comparison with a control (pHT 8.10). At pHT 8.10, ammonia oxidation rates in burrow wall sediments were, on average, fivefold greater than in surface sediments. However, at all acidified pH values (pH 〈 = 7.90), ammonia oxidation rates in burrow sediments were significantly inhibited (by 79-97%; p 〈 0.01), whereas rates in surface sediments were unaffected. Both bacterial and archaeal abundances increased significantly as pHT declined; by contrast, relative abundances of bacterial and archaeal ammonia oxidation (amoA) genes did not vary. This research suggests that OA could cause substantial reductions in total benthic ammonia oxidation rates in coastal bioturbated sediments, leading to corresponding changes in coupled nitrogen cycling between the benthic and pelagic realms.
Keywords:
Acid-base regulation; Alkalinity, total; Alkalinity, total, standard deviation; Ammonia, oxidation rate; Aragonite saturation state; Aragonite saturation state, standard deviation; Benthos; Bicarbonate ion; 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 deviation; Carbon, inorganic, total; Carbon, organic, total; Carbon, total; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Change; Coast and continental shelf; Core; Date; DEPTH, sediment, experiment; Depth comment; Entire community; EXP; Experiment; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gene abundance; Gene expression (incl. proteomics); Haemolymph, pH; Identification; Jennycliff_Bay; Laboratory experiment; Mesocosm or benthocosm; Nitrogen, inorganic; Nitrogen, organic; Nitrogen, total; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Other metabolic rates; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Polar; Potentiometric; Potentiometric titration; Salinity; Salinity, standard deviation; Soft-bottom community; Species; Table; Temperature, water; Temperature, water, standard deviation; Treatment; Type; Upogebia deltaura
Type:
Dataset
Format:
text/tab-separated-values, 13415 data points
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