Effects of elevated temperature on microbial breakdown of seagrass leaf and tea litter biomass
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Effects of elevated temperature on microbial breakdown of seagrass leaf and tea litter biomass Stacey M. Trevathan-Tackett
. Kasper E. Brodersen . Peter I. Macreadie
Received: 12 June 2020 / Revised: 12 October 2020 / Accepted: 21 October 2020 Ó Springer Nature Switzerland AG 2020
Abstract Seagrass ecosystems are globally-significant ‘blue carbon’ sinks; however, there is concern that this capacity will decline if rising ocean temperatures accelerate microbial decomposition. Decomposition of plant litter is a key process in the global carbon cycle—it influences how much carbon is available for sequestration. Therefore, understanding the biogeochemistry underlying decomposition is essential to predicting the capacity of seagrass ecosystems to act as carbon sinks in the future. Here, we tracked the breakdown of standardised and natural litter of varying chemical recalcitrance (rooibos tea [ seagrass leaves [ green tea) combined with highly-sensitive microsensor technology to test (a) how elevated water temperatures affect short-term microbial turnover, and (b) provide novel information
Responsible Editor: Scott Bridgham
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10533-020-00715-1) contains supplementary material, which is available to authorized users. S. M. Trevathan-Tackett (&) P. I. Macreadie School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Geelong, VIC, Australia e-mail: [email protected] K. E. Brodersen Department of Biology, Marine Biological Section, University of Copenhagen, Helsingør, Denmark
on how the decay dynamics of the tea litter compare to those of natural litter. We found that increased temperatures (? 5–10 °C) boosted microbial activity for all substrates, exhibited as enhanced decay, oxygen consumption and sulphate reduction. Within the 1-month experiment, the green tea litter had a rapid Q10 response to the temperature increase, quickly exhausting the resources for microbes, while the response of the rooibos tea and seagrass litters became more apparent toward the end of the experiment. Our results suggest that the tea litters capture a range of decomposition traits and can be compared with natural litter using traditional exponential decay models. The enhanced temperature-driven organic matter turnover, even under anoxic conditions, highlights the vulnerability of fresh litter to microbial attack during the early stages of decay and the potential weakening of blue carbon accumulation rates under future climatic conditions. Keywords Detritus Inundation Remineralisation Sulphate reduction Tea bag index Warming
Introduction Coastal vegetated ecosystems, including seagrass meadows, have received widespread attention as globally significant carbon sinks, having the ability
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Biogeochemistry
to rapidly accumulate and store carbon in their soils, known as ‘blue carbon’ (Laffoley and Grimsditch 2009). While it is known that
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