Life Sciences Commons^™

Methane Emissions In Seagrass Meadows As A Small Offset To Carbon Sequestration, Yvonne Y. Y. Yau, Gloria Reithmaier, Caludia Majtényi-Hill, Oscar Serrano, Nerea Piñeiro-Juncal, Martin Dahl, Miguel A. Mateo, Stefano Bonaglia, Isaac R. Santos

Research outputs 2022 to 2026

Seagrass meadows are effective carbon sinks due to high primary production and sequestration in sediments. However, methane (CH4) emissions can partially counteract their carbon sink capacity. Here, we measured diffusive sediment-water and sea-air CO2 and CH4 fluxes in a coastal embayment dominated by Posidonia oceanica in the Mediterranean Sea. High-resolution timeseries observations revealed large spatial and temporal variability in CH4 concentrations (2–36 nM). Lower sea-air CH4 emissions were observed in an area with dense seagrass meadows compared to patchy seagrass. A 6%−40% decrease of CH4 concentration in the surface water around noon indicates that photosynthesis likely limits CH4 fluxes. Sediments …

Sinking Seaweed In The Deep Ocean For Carbon Neutrality Is Ahead Of Science And Beyond The Ethics, Aurora M. Ricart, Dorte Krause-Jensen, Kasper Hancke, Nichole N. Price, Pere Masqué, Carlos M. Duarte

Research outputs 2022 to 2026

Sinking vast amounts of seaweed in the deep ocean is currently being proposed as a promising ocean carbon dioxide removal strategy as well as a natural-based solution to mitigate climate change. Still, marketable carbon offsets through large-scale seaweed sinking in the deep ocean lack documentation and could involve unintended environmental and social consequences. Managing the risks requires a number of urgent actions.

The Renaissance Of Odum's Outwelling Hypothesis In 'Blue Carbon' Science, Isaac R. Santos, David J. Burdige, Tim C. Jennerjahn, Steven Bouillon, Alex Cabral, Oscar Serrano, Thomas Wernberg, Karen Filbee-Dexter, Julia A. Guimond, Joseph J. Tamborski

Research outputs 2014 to 2021

The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal vegetated ecosystems. The term has paved the way for the development of programs and policies that preserve and restore these threatened coastal ecosystems for climate change mitigation. Blue carbon research has focused on quantifying carbon stocks and burial rates in sediments or accumulating as biomass. This focus on habitat-bound carbon led us to losing sight of the mobile blue carbon fraction. Oceans, the largest active reservoir of carbon, have become somewhat of a blind spot. Multiple recent investigations have revealed high …

Organic Chemistry Insights For The Exceptional Soil Carbon Storage Of The Seagrass Posidonia Australis, Oscar Serrano, Mohammad Rozaimi, Paul Lavery, Ronald J. Smernik

Research outputs 2014 to 2021

The high organic carbon (OC) stores in seagrass meadows have led to their recognition as significant Blue Carbon sinks, though the diagenetic conditions that enable OC retention in seagrass soils remain poorly understood. In this study, seagrass soils were sampled from a Posidonia australis meadow in Oyster Harbour (Albany; south-western Australia) to investigate the preservation of sedimentary OC. We analysed soil characteristics (colour, grain size and redox potential), radiocarbon age, and characterised the soil organic matter (OM) using solid state CP/MAS 13C NMR spectroscopy to examine the preservation of OM down the soil profile. There was minimal change in organic …

Comment On 'Geoengineering With Seagrasses: Is Credit Due Where Credit Is Given?', Peter I. Macreadie, Carolyn J. Ewers-Lewis, Ashley A. Whitt, Quinn Ollivier, Stacey M. Trevathan-Tackett, Paul Carnell, Oscar Serrano

Research outputs 2014 to 2021

Over the past decade scientists around the world have sought to estimate the capacity of seagrass meadows to sequester carbon, and thereby understand their role in climate change mitigation. The number of studies reporting on seagrass carbon accumulation rates is still limited, but growing scientific evidence supports the hypothesis that seagrasses have been efficiently locking away CO2 for decades to millennia (e.g. Macreadie et al 2014, Mateo et al 1997, Serrano et al 2012). Johannessen and Macdonald (2016), however, challenge the role of seagrasses as carbon traps, claiming that gains in carbon storage by seagrasses …

Sequestration Of Macroalgal Carbon: The Elephant In The Blue Carbon Room, Dorte Krause-Jensen, Paul Lavery, Oscar Serrano, Nu´Ria Marba, Pere Masque´, Carlos M. Duarte

Research outputs 2014 to 2021

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) …

Effects Of Small-Scale, Shading-Induced Seagrass Loss On Blue Carbon Storage: Implications For Management Of Degraded Seagrass Ecosystems [Dataset], Stacey M. Trevathan-Tackett, Caitlin Wessel, Just Cebrian, Peter J. Ralph, Pere Masque´, Peter I. Macreadie

Research Datasets

1. Seagrass meadows are important global ‘blue carbon’ sinks. Despite a 30% loss of seagrasses globally during the last century, there is limited empirical research investigating the effects of disturbance and loss of seagrass on blue carbon stocks.

2. In this study, we hypothesised that seagrass loss would reduce blue carbon stocks. Using shading cloth, we simulated small-scale die-offs of two subtropical seagrass species, Halodule wrightii and Thalassia testudinum, in a dynamic northern Gulf of Mexico lagoon. The change in quantity and quality of sediment organic matter and organic carbon were compared among kill, control and bare plots before the …

Low Carbon Sink Capacity Of Red Sea Mangroves, Hanan Almahasheer, Óscar Serrano, Carlos M. Duarte, Ariane Arias-Ortiz, Pere Masqué, Xabier Irigoien

Research outputs 2014 to 2021

Mangroves forests of Avicennia marina occupy about 135 km² in the Red Sea and represent one of the most important vegetated communities in this otherwise arid and oligotrophic region. We assessed the soil organic carbon (C_org) stocks, soil accretion rates (SAR; mm y^-1) and soil C_org sequestration rates (g C_org m^-2 yr^-1) in 10 mangrove sites within four locations along the Saudi coast of the Central Red Sea. Soil C_org density and stock in Red Sea mangroves were among the lowest reported globally, with an average of 4 ± …