Comparison of Three Methods for the Quantification of Sediment Organic Carbon in Salt Marshes of the Rubicon Estuary, Tasmania, Australia

Abstract. Coastal ecosystems are typically highly productive, and the sediments in these systems receive organic matter from a variety of local and imported sources. To assess if general patterns are present in the origin of carbon sources for sedimentary bacteria and their relation to the origin of the sediment organic carbon pool, we compiled both literature and new data on δ13C of bacterial biomarkers (the phospholipid derived fatty acids i+a15:0), along with δ13C data on sediment organic carbon (δ13CTOC) and macrophyte biomass from a variety of typical near-coastal systems. These systems included mangroves, salt marshes (both C3 and C4-dominated sites), seagrass beds, and macroalgae-based systems, as well as unvegetated sediments. First, our δ13Ci+a15:0 data showed large variability over the entire range of δ13CTOC, indicating that in many settings, bacteria may depend on carbon derived from various origins. Secondly, systems where local macrophyte production is the major supplier of organic carbon for in situ decomposition are generally limited to organic carbon-rich, peaty sites (TOC>10 wt%), which are likely to make up only a small part of the global area of vegetated coastal systems. These carbon-rich sediments also provided a field based estimate of isotopic fractionation between bacterial carbon sources and biomarkers (-3.7±2.1), which is similar to the expected value of about -3 associated with the biosynthesis of fatty acids. Thirdly, only in systems with low TOC (below ~1 wt%), we consistently found that bacteria were selectively utilizing an isotopically enriched carbon source, which may be root exudates but more likely is derived from microphytobenthos. In other systems with between ~1 and 10 wt% TOC, bacteria appear to show on average little selectivity and δ13Ci+a15:0 data generally follow the δ13CTOC, even in systems where the TOC is a mixture of algal and macrophyte sources that generally are believed to have a very different degradability.

Download Full-text

Seasonal Species Variation of Sediment Organic Carbon Stocks in Salt Marshes of Tuticorin Area, Southern India

Wetlands ◽

10.1007/s13157-018-1094-6 ◽

2018 ◽

Vol 39 (3) ◽

pp. 483-494 ◽

Cited By ~ 1

Author(s):

Thanamegam Kaviarasan ◽

Hans Uwe Dahms ◽

Murugaiah Santhosh Gokul ◽

Santhaseelan Henciya ◽

Krishnan Muthukumar ◽

...

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Carbon Stocks ◽

Southern India ◽

Species Variation ◽

Sediment Organic Carbon

Download Full-text

Sediment Organic Carbon Accumulation and Erosion-induced CO 2 Emissions in the Delaware Bay Estuarine Salt Marshes

10.1002/essoar.10500786.1 ◽

2019 ◽

Author(s):

Beatrice OHara ◽

Daria Nikitina ◽

Alan Geyer ◽

Daniel Jennings

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Delaware Bay ◽

Carbon Accumulation ◽

Sediment Organic Carbon

Download Full-text

Bacterial carbon sources in coastal sediments: a review based on stable isotope data of biomarkers

Biogeosciences Discussions ◽

10.5194/bgd-2-1617-2005 ◽

2005 ◽

Vol 2 (5) ◽

pp. 1617-1644 ◽

Cited By ~ 2

Author(s):

S. Bouillon ◽

H. T. S. Boschker

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Carbon Sources ◽

Isotopic Fractionation ◽

Lipid Synthesis ◽

Coastal Sediments ◽

Large Variability ◽

Coastal Systems ◽

Sediment Organic Carbon ◽

Bacterial Lipid

Abstract. Coastal ecosystems are typically highly productive, and recieve organic matter from a variety of local and imported sources. To assess if general patterns are present in the origin of carbon sources for sedimentary bacteria and their relation to the origin of the sediment organic carbon pool, we compiled both literature and new data on δ13C of bacterial biomarker PLFA (the phospholipid derived fatty acids i+a15:0) along with δ13C data on sediment organic carbon δ13CTOC and macrophyte biomass. Such data were collected from a variety of typical near-coastal systems, including mangroves, salt marshes (both C3 and C4-dominated sites), seagrass beds, and macroalgae-based systems, as well as unvegetated sediments. First, our δ13Ci+a15:0 data showed a large variability over the entire range of δ13CTOC, indicating that in many settings, bacteria may depend on carbon derived from various origins. Secondly, systems where local macrophyte production is the major supplier of organic carbon for in situ decomposition are generally limited to organic carbon-rich, peaty sites (TOC>10 wt%) which are likely to make up only a small part of the global area of vegetated coastal systems. These carbon-rich sediments also provided a field based estimate of isotopic fractionation in bacterial lipid synthesis (-3.7±2.1), that is similar to the expected value. Thirdly, only in systems with low TOC (below ~1 wt%), we consistently found that bacteria were on average selectively utilizing an isotopically enriched carbon source, which may be root exudates but more likely is derived from microphytobenthos. In other systems with between ~1 and 10 wt% TOC, bacteria appear to show on average little selectivity and δ13Ci+a15:0 data generally follow the δ13CTOC, even in systems where the TOC is a mixture of algal and macrophyte sources that generally are believed to have a very different degradability.

Download Full-text

Effects of marine pollution, climate, and tidal range on biomass and sediment organic carbon in Chinese mangrove forests

CATENA ◽

10.1016/j.catena.2021.105270 ◽

2021 ◽

Vol 202 ◽

pp. 105270

Author(s):

Gang Wang ◽

Minerva Singh ◽

Jiaqiu Wang ◽

Ling Xiao ◽

Dongsheng Guan

Keyword(s):

Organic Carbon ◽

Marine Pollution ◽

Tidal Range ◽

Mangrove Forests ◽

Sediment Organic Carbon

Download Full-text

Soil-Aggregate-Associated Organic Carbon Along Vegetation Zones in Tidal Salt Marshes in the Liaohe Delta

CLEAN - Soil Air Water ◽

10.1002/clen.201800049 ◽

2018 ◽

Vol 46 (4) ◽

pp. 1800049 ◽

Cited By ~ 1

Author(s):

Rong Mao ◽

Si-Yuan Ye ◽

Xin-Hou Zhang

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Soil Aggregate ◽

Vegetation Zones ◽

Liaohe Delta

Download Full-text

Blooms of cyanobacteria in a temperate Australian lagoon system post and prior to European settlement

Biogeosciences ◽

10.5194/bg-13-3677-2016 ◽

2016 ◽

Vol 13 (12) ◽

pp. 3677-3686 ◽

Cited By ~ 6

Author(s):

Perran L. M. Cook ◽

Miles Jennings ◽

Daryl P. Holland ◽

John Beardall ◽

Christy Briles ◽

...

Keyword(s):

Organic Carbon ◽

Carbon Content ◽

Phosphorus Release ◽

Cyanobacterial Blooms ◽

Organic Carbon Content ◽

Lagoon System ◽

European Settlement ◽

Current Period ◽

Sediment Organic Carbon ◽

Nitrogen Inputs

Abstract. Blooms of noxious N2 fixing cyanobacteria such as Nodularia spumigena are a recurring problem in some estuaries; however, the historic occurrence of such blooms in unclear in many cases. Here we report the results of a palaeoecological study on a temperate Australian lagoon system (the Gippsland Lakes) where we used stable isotopes and pigment biomarkers in dated cores as proxies for eutrophication and blooms of cyanobacteria. Pigment proxies show a clear signal, with an increase in cyanobacterial pigments (echinenone, canthaxanthin and zeaxanthin) in the period coinciding with recent blooms. Another excursion in these proxies was observed prior to the opening of an artificial entrance to the lakes in 1889, which markedly increased the salinity of the Gippsland Lakes. A coincident increase in the sediment organic-carbon content in the period prior to the opening of the artificial entrance suggests that the bottom waters of the lakes were more stratified and hypoxic, which would have led to an increase in the recycling of phosphorus. After the opening of the artificial entrance, there was a ∼  60-year period with low values for the cyanobacterial proxies as well as a low sediment organic-carbon content suggesting a period of low bloom activity associated with the increased salinity of the lakes. During the 1940s, the current period of re-eutrophication commenced, as indicated by a steadily increasing sediment organic-carbon content and cyanobacterial pigments. We suggest that increasing nitrogen inputs from the catchment led to the return of hypoxia and increased phosphorus release from the sediment, which drove the re-emergence of cyanobacterial blooms.

Download Full-text