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Response of seagrass 'blue carbon' stocks to increased water temperatures

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journal contribution
posted on 2018-01-01, 00:00 authored by Peter MacreadiePeter Macreadie, S S S Hardy
Seagrass meadows are globally important sinks of ‘Blue Carbon’, but warming water
temperatures due to climate change may undermine their capacity to sequester and retain
organic carbon (Corg). We tested the effects of warming on seagrass Corg stocks in situ by
transplanting seagrass soil cores along a thermal plume generated by a coal-fired power plant
in a seagrass-dominated estuary (Lake Macquarie, Australia). Transplanted cores were subjected
to temperatures 2 and 4 ◦C above ambient temperatures and Corg content was measured after
7, 30, 90 and 180 days. We were unable to detect any significant effect of warming on Corg
concentration, stocks, chemical composition (as measured by labile, recalcitrant, refractory ratios),
or microbial abundance at any time point. In fact, Corg levels were temporally variable. These findings
contrast those of previous studies (mostly laboratory-based) that have reported increases in microbial
remineralisation (breakdown) of Corg in response to warming. To explain the lack of any detectable
warming effect, we suggest that higher temperatures, longer durations of warming exposure,
or additional stressors (e.g., oxygen exposure) may be needed to overcome microbial activation
barriers and stimulate Corg remineralisation.

History

Journal

Diversity

Volume

10

Issue

4

Season

Special Issue: Effects of Human Disturbances and Climate Forcing on Marine Vegetation)

Article number

115

Pagination

1 - 9

Publisher

MDPI

Location

Basel, Switzerland

ISSN

1424-8220

Language

eng

Publication classification

C Journal article; C1 Refereed article in a scholarly journal

Copyright notice

2018, The Authors