Effects of a nutrient enrichment pulse on blue carbon ecosystems

• Published in: Marine pollution bulletin Vol. 165; p. 112024
• Main Authors: Palacios, Maria M., Trevathan-Tackett, Stacey M., Malerba, Martino E., Macreadie, Peter I.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2021; Elsevier BV
• Subjects: Ammonium; Ammonium compounds; Australia; Blue carbon; Carbon; Carbon - analysis; Carbon cycle; Carbon dioxide; Carbon sinks; Coastal ecosystems; Community structure; Cycles; Ecosystem; Ecosystems; Eutrophication; Fertilizer; Fluxes; Mangrove; Mangroves; marine pollution; Microbiome; Mineral nutrients; Nitrogen; Nutrient enrichment; Nutrient retention; Nutrients; salt marshes; Saltmarsh; Soil; Soil carbon; Soils; Stocks; tea; Wetlands; Australia; Australia; Mangrove; Fertilizer; Saltmarsh; Soil carbon; Microbiome
• ISSN: 0025-326X; 1879-3363; 1879-3363
• DOI: 10.1016/j.marpolbul.2021.112024

Coastal ecosystems are under increasing pressure from land-derived eutrophication in most developed coastlines worldwide. Here, we tested for 277 days the effects of a nutrient pulse on blue carbon retention and cycling within an Australian temperate coastal system. After 56 days of exposure, saltmarsh and mangrove plots subject to a high-nutrient treatment (~20 g N m−2 yr−1 and ~2 g P m−2 yr−1) had ~23% lower superficial soil carbon stocks. Mangrove plots also experienced a ~33% reduction in the microbe Amplicon Sequence Variant richness and a shift in community structure linked to elevated ammonium concentrations. Live plant cover, tea litter decomposition, and soil carbon fluxes (CO2 and CH4) were not significantly affected by the pulse. Before the end of the experiment, soil carbon- and nitrogen-cycling had returned to control levels, highlighting the significant but short-lived impact that a nutrient pulse can have on the carbon sink capacity of coastal wetlands. •We tested the impact of a fertiliser pulse on Australian mangroves and saltmarshes.•The nutrient pulse led to 23% lower soil carbon stocks in both ecosystems.•The microbial ASV richness decreased by 33% in mangrove plots.•Plant cover, litter decomposition, and soil carbon fluxes remained unaffected.•The nutrient pulse had a significant, but short-lived impact on both ecosystems.