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Carbon and nitrogen dynamics in shallow photic systems: Interactions between macroalgae, microalgae, and bacteria
Hardison, AK Anderson, Iris C. Canuel, Elizabeth A. Tobias, CR Veuger, B
Hardison, AK
Anderson, Iris C.
Canuel, Elizabeth A.
Tobias, CR
Veuger, B
Abstract
We tracked carbon (C) and nitrogen (N) uptake into sediments in the presence and absence of benthic macroalgae using dual stable isotope tracers in combination with compound-specific isotope analyses of hydrolyzable amino acids and phospholipid-linked fatty acids to quantify the uptake and retention of C and N within bulk sediments, benthic microalgae (BMA), and heterotrophic bacteria. Stable isotope tracers (as (15)NH(4)(+) and H(13)CO(3)(-)) were added to mesocosms either via the surface water or pore water for the first 14 d of the 42-d experiment. Macroalgae and sediments exposed to ambient light and dark cycles rapidly took up label from both sources and retained label for at least 4 weeks after isotope additions ended. BMA dominated sediment uptake of (13)C and (15)N, initially accounting for 100% of total uptake. Over time, heterotrophic bacterial uptake became relatively more important, increasing from 0% on day 1 to 20-50% on day 42, indicating a close coupling between BMA and bacterial production. In treatments with macroalgae, sediment (13)C and (15)N uptake was similar to 40% lower than treatments without macroalgae, likely because of shading of the sediment surface by macroalgae, which decreased BMA production, which in turn decreased bacterial production. Overall, sediments served as a sink for C and N through uptake and retention by the microbial community, but retention was lower in the presence of macroalgae.
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2011-01-01
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lo.2011.56.4.1489.pdf
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Physical Sciences Peer-Reviewed Articles, Temperate Coastal Lagoon; Chaetomorpha-Linum; Nutrient Availability; Microbial Community; N-15 Incorporation; Marine-Sediments; Benthic Algae; Dense Mats; D-Alanine; Growth
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Virginia Institute of Marine Science
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https://doi.org/10.4319/lo.2011.56.4.1489