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| Titel |
Seagrass meadows as a globally significant carbonate reservoir |
| VerfasserIn |
I. Mazarrasa, N. Marbá, C. E. Lovelock, O. Serrano, P. S. Lavery, J. W. Fourqurean, H. Kennedy, M. A. Mateo, D. Krause-Jensen, A. D. L. Steven, C. M. Duarte |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 16 ; Nr. 12, no. 16 (2015-08-24), S.4993-5003 |
| Datensatznummer |
250118071
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| Publikation (Nr.) |
 copernicus.org/bg-12-4993-2015.pdf |
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| Zusammenfassung |
| There has been growing interest in quantifying the capacity of seagrass
ecosystems to act as carbon sinks as a natural way of offsetting
anthropogenic carbon emissions to the atmosphere. However, most of the
efforts have focused on the particulate organic carbon (POC) stocks and accumulation
rates and ignored the particulate inorganic carbon (PIC) fraction, despite important
carbonate pools associated with calcifying organisms inhabiting the meadows,
such as epiphytes and benthic invertebrates, and despite the relevance that carbonate
precipitation and dissolution processes have in the global carbon cycle. This
study offers the first assessment of the global PIC stocks in seagrass
sediments using a synthesis of published and unpublished data on sediment
carbonate concentration from 403 vegetated and 34 adjacent un-vegetated
sites. PIC stocks in the top 1 m of sediment ranged between 3 and
1660 Mg PIC ha−1, with an average of 654 ± 24 Mg PIC ha−1,
exceeding those of POC reported in previous studies by about a factor of 5. Sedimentary
carbonate stocks varied across seagrass communities, with meadows dominated
by Halodule, Thalassia or Cymodocea supporting the
highest PIC stocks, and tended to decrease polewards at a rate of
−8 ± 2 Mg PIC ha−1 per degree of latitude (general linear
model, GLM; p < 0.0003).
Using PIC concentrations and estimates of sediment accretion in seagrass
meadows, the mean PIC accumulation rate in seagrass sediments is found to be
126.3 ± 31.05 g PIC m−2 yr−1. Based on the global extent
of seagrass meadows (177 000 to 600 000 km2), these ecosystems
globally store between 11 and 39 Pg of PIC in the top metre of sediment and
accumulate between 22 and 75 Tg PIC yr−1, representing a significant
contribution to the carbonate dynamics of coastal areas. Despite the fact that these
high rates of carbonate accumulation imply CO2 emissions from
precipitation, seagrass meadows are still strong CO2 sinks as
demonstrated by the comparison of carbon (PIC and POC) stocks between vegetated
and adjacent un-vegetated sediments. |
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