Coastal Sediment Nutrient Enrichment Alters Seagrass Blue Carbon Sink Capacity

Abstract. Although seagrasses cover only a minor fraction of the ocean seafloor, their carbon sink capacity accounts for nearly one-fifth of the total oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. We sampled 10 eelgrass (Zostera marina) meadows in Finland and 10 in Denmark to explore seagrass carbon stocks (Corg stock) and carbon accumulation rates (Corg accumulation) in the Baltic Sea area. The study sites represent a gradient from sheltered to exposed locations in both regions to reflect expected minimum and maximum stocks and accumulation. The Corg stock integrated over the top 25 cm of the sediment averaged 627 g C m−2 in Finland, while in Denmark the average Corg stock was over 6 times higher (4324 g C m−2). A conservative estimate of the total organic carbon pool in the regions ranged between 6.98 and 44.9 t C ha−1. Our results suggest that the Finnish eelgrass meadows are minor carbon sinks compared to the Danish meadows, and that majority of the Corg produced in the Finnish meadows is exported. Our analysis further showed that > 40 % of the variation in the Corg stocks was explained by sediment characteristics, i.e. dry density, porosity and silt content. In addition, our analysis show that the root : shoot ratio of Z. marina explained > 12 % and the contribution of Z. marina detritus to the sediment surface Corg pool explained > 10 % of the variation in the Corg stocks. The mean monetary value for the present carbon storage and carbon sink capacity of eelgrass meadows in Finland and Denmark, were 281 and 1809 EUR ha−1, respectively. For a more comprehensive picture of seagrass carbon storage capacity, we conclude that future blue carbon studies should, in a more integrative way, investigate the interactions between sediment biogeochemistry, seascape structure, plant species architecture and the hydrodynamic regime.

Download Full-text

Faculty Opinions recommendation of Seagrass community metabolism: Assessing the carbon sink capacity of seagrass meadows.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.7665956.7978054 ◽

2011 ◽

Author(s):

Scott Doney

Keyword(s):

Carbon Sink ◽

Community Metabolism ◽

Seagrass Meadows ◽

Seagrass Community ◽

Sink Capacity

Download Full-text

Αλλαγές στις θαλάσσιες βακτηριακές κοινότητες σε συνθήκες εμπλουτισμού με θρεπτικά

10.12681/eadd/40875 ◽

2014 ◽

Author(s):

Στυλιανός Φοδελιανάκης

Keyword(s):

Organic Matter ◽

Water Column ◽

Nutrient Enrichment ◽

Eastern Mediterranean ◽

Community Diversity ◽

Coastal Sediment ◽

Common Source ◽

Composition And Structure ◽

Taxonomic Groups ◽

Bacterioplankton Communities

Nutrient enrichment is a common source of disturbance for marineecosystems. A prerequisite for the prediction of the effects of nutrient enrichment atthe ecosystem level is the understanding of the ecological mechanisms governingbacterioplankton communities, due to their high affinity with nutrients. The aim ofthis thesis was to examine changes in the composition and structure ofbacterioplankton communities of the water column and coastal sediment undernutrient enrichment. Three studies were conducted for that purpose: two in closedexperimental conditions and one examining changes in situ. In the first two studies,changes in the water column bacterioplankton communities were examined after Paddition and in nutrient enriched habitats, respectively. In the third study, changes inthe communities of coastal sediment were examined with and without the additionof organic matter and aeration of the water column. The main conclusions from theresults of this thesis were:a) Bacterioplankton communities of the Eastern Mediterranean show a high degreeof resistance to short-term P addition, although their biomass and production islimited by P.b) Five abundant taxonomic groups showed a similar pattern of change across threedifferent nutrient enriched habitats. These groups could be potentially used asindicators for monitoring nutrient enrichment at the water column.c) After incubation under presence or absence of organic enrichment, sedimentbacterial communities originating from different habitats clustered based on theincubation conditions rather than on the area of origin. That occurred faster for twoout of the three areas, where the amount of organic matter in the sediment wasinitially higher and bacterial community diversity was lower. These results indirectlysupport the theory of Baas-Becking that "everything is everywhere but theenvironment selects" and the positive correlation between diversity and communitystability.

Download Full-text

Analysis of the marine carbon sink capacity in China

Sustainable Marine Resource Utilization in China ◽

10.1016/b978-0-12-819911-4.00004-7 ◽

2020 ◽

pp. 103-144

Author(s):

Malin Song ◽

Xiongfeng Pan ◽

Xianyou Pan

Keyword(s):

Carbon Sink ◽

Sink Capacity

Download Full-text

Beyond burial: lateral exchange is a significant atmospheric carbon sink in mangrove forests

Biology Letters ◽

10.1098/rsbl.2018.0200 ◽

2018 ◽

Vol 14 (7) ◽

pp. 20180200 ◽

Cited By ~ 35

Author(s):

Damien T. Maher ◽

Mitchell Call ◽

Isaac R. Santos ◽

Christian J. Sanders

Keyword(s):

Organic Carbon ◽

Dissolved Inorganic Carbon ◽

Carbon Sink ◽

Blue Carbon ◽

Mangrove Forests ◽

Carbon Framework ◽

Sequestration Potential ◽

Seagrass Ecosystems ◽

Atmospheric Carbon

The blue carbon paradigm has evolved in recognition of the high carbon storage and sequestration potential of mangrove, saltmarsh and seagrass ecosystems. However, fluxes of the potent greenhouse gases CH 4 and N 2 O, and lateral export of carbon are often overlooked within the blue carbon framework. Here, we show that the export of dissolved inorganic carbon (DIC) and alkalinity is approximately 1.7 times higher than burial as a long-term carbon sink in a subtropical mangrove system. Fluxes of methane offset burial by approximately 6%, while the nitrous oxide sink was approximately 0.5% of burial. Export of dissolved organic carbon and particulate organic carbon to the coastal zone is also significant and combined may account for an atmospheric carbon sink similar to burial. Our results indicate that the export of DIC and alkalinity results in a long-term atmospheric carbon sink and should be incorporated into the blue carbon paradigm when assessing the role of these habitats in sequestering carbon and mitigating climate change.

Download Full-text

Low Carbon sink capacity of Red Sea mangroves

Scientific Reports ◽

10.1038/s41598-017-10424-9 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 43

Author(s):

Hanan Almahasheer ◽

Oscar Serrano ◽

Carlos M. Duarte ◽

Ariane Arias-Ortiz ◽

Pere Masque ◽

...

Keyword(s):

Red Sea ◽

Carbon Sink ◽

Low Carbon ◽

Sink Capacity

Download Full-text

CO2 and nutrient-driven changes across multiple levels of organization in Zostera noltii ecosystems

Biogeosciences Discussions ◽

10.5194/bgd-11-5239-2014 ◽

2014 ◽

Vol 11 (4) ◽

pp. 5239-5274 ◽

Cited By ~ 3

Author(s):

B. Martínez-Crego ◽

I. Olivé ◽

R. Santos

Keyword(s):

Organic Matter ◽

Carbon Sink ◽

Co2 Enrichment ◽

Population Level ◽

Zostera Noltii ◽

Biological Organization ◽

Seagrass Meadows ◽

Plant Biochemistry ◽

Sink Capacity ◽

High Nutrient

Abstract. Increasing evidence emphasizes that the effects of human impacts on ecosystems must be investigated using designs that incorporate the responses across levels of biological organization as well as the effects of multiple stressors. Here we implemented a mesocosm experiment to investigate how the effects of CO2 enrichment and its interaction with eutrophication, scale-up from changes in primary producers at the individual- (biochemistry) or population-level (production, reproduction, and/or abundance) to higher levels of community (macroalgae abundance, herbivory, and global metabolism) and ecosystem organization (detritus release and carbon sink capacity). The responses of Zostera noltii seagrass meadows growing in low- and high- nutrient field conditions were compared. In both meadows, the effect of elevated CO2 levels was mediated by epiphyte proliferation (mostly the cyanobacterium Microcoleus spp.), but not through changes in plant biochemistry or population-level traits. In the low-nutrient meadow, epiphyte proliferation suppressed the CO2 benefits on Z. noltii leaf production and led to increased detritus and decreased organic matter in sediment. Faster and stronger responses to nutrients than to CO2 were observed. Nutrient addition enhanced the nutritional quality of Z. noltii (high N, low C : N and phenolics) and the loss of leaves and shoots, while promoted the proliferation of pennate diatoms and purple bacteria. These changes led to a reduced sediment organic matter, but had no significant effects on herbivory nor on community metabolism. Interestingly, the interaction with CO2 attenuated eutrophication effects. In the high-nutrient meadow, a striking shoot decline caused by amphipod overgrazing was observed, with no response to CO2 and nutrient additions. Our results reveal that under future scenarios of CO2, the responses of seagrass ecosystems will be complex, being mediated by epiphyte proliferation rather than by effects on plant biochemistry. The multi-level responses of the system to nutrients overwhelmed those to CO2 enrichment, but the interaction between stressors reduced the effects of eutrophication. Both, CO2 and nutrient enrichments can reduce the carbon sink capacity of seagrass meadows.

Download Full-text

Sequestration of macroalgal carbon: the elephant in the Blue Carbon room

Biology Letters ◽

10.1098/rsbl.2018.0236 ◽

2018 ◽

Vol 14 (6) ◽

pp. 20180236 ◽

Cited By ~ 45

Author(s):

Dorte Krause-Jensen ◽

Paul Lavery ◽

Oscar Serrano ◽

Núria Marbà ◽

Pere Masque ◽

...

Keyword(s):

Paradigm Shift ◽

Carbon Sink ◽

Blue Carbon ◽

Coastal Habitats ◽

Management Actions ◽

Carbon Burial

Macroalgae form the most extensive and productive benthic marine vegetated habitats globally but their inclusion in Blue Carbon (BC) strategies remains controversial. We review the arguments offered to reject or include macroalgae in the BC framework, and identify the challenges that have precluded macroalgae from being incorporated so far. Evidence that macroalgae support significant carbon burial is compelling. The carbon they supply to sediment stocks in angiosperm BC habitats is already included in current assessments, so that macroalgae are de facto recognized as important donors of BC. The key challenges are (i) documenting macroalgal carbon sequestered beyond BC habitat, (ii) tracing it back to source habitats, and (iii) showing that management actions at the habitat lead to increased sequestration at the sink site. These challenges apply equally to carbon exported from BC coastal habitats. Because of the large carbon sink they support, incorporation of macroalgae into BC accounting and actions is an imperative. This requires a paradigm shift in accounting procedures as well as developing methods to enable the capacity to trace carbon from donor to sink habitats in the ocean.

Download Full-text