Vulnerability of seagrass blue carbon to microbial attack following exposure to warming and oxygen

Macreadie, Peter I.; Atwood, Trisha B.; Seymour, Justin R.; Fontes, Maria Luiza Schmitz; Sanderman, Jonathan; Nielsen, Daniel A.; Connolly, Rod M.

doi:10.1016/j.scitotenv.2019.05.462

Cited by 51 publications

(21 citation statements)

References 73 publications

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“…In general, organic-rich coastal sediments along the continental shelf that experience high sedimentation rates and rapid oxygen depletion with depth are hypothesized to be the most sensitive to disturbances. Disturbances that physically disrupt these organicrich coastal sediments can enhance oxygen exposure and mix fresh C pools with degraded ones, priming microbial activity, and the breakdown of C (Bianchi, 2011;Lovelock et al, 2017;Macreadie et al, 2019). Conversely, recent estimates have suggested that a large portion of deep-sea sediment C occurs in oxygenated sediments, but that physical and chemical protections make that C inaccessible to heterotrophic metabolism (Keil and Hedges, 1993;Hedges and Keil, 1995;Estes et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Global Patterns in Marine Sediment Carbon Stocks

et al. 2020

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To develop more accurate global carbon (C) budgets and to better inform management of human activities in the ocean, we need high-resolution estimates of marine C stocks. Here we quantify global marine sedimentary C stocks at a 1-km resolution, and find that marine sediments store 2322 (2239–2391) Pg C in the top 1 m (nearly twice that of terrestrial soils). Sediments in abyss/basin zones account for 79% of the global marine sediment C stock, and 49% of that stock is within the 200-mile Exclusive Economic Zones of countries. Currently, only ∼2% of sediment C stocks are located in highly to fully protected areas that prevent the disturbance of the seafloor. Our results show that marine sediments represent a large and globally important C sink. However, the lack of protection for marine C stocks makes them highly vulnerable to human disturbances that can lead to their remineralization to CO2, further aggravating climate change impacts.

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Section: Discussionmentioning

confidence: 99%

Global Patterns in Marine Sediment Carbon Stocks

et al. 2020

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“…There are a variety of other factors to consider when examining the overall carbon budget in seagrass meadows, and when determining whether a given area is a net sink or source of CO 2 . For example, anthropogenic disturbances such as coastal development, shading, clam harvesting, and dredging can expose sediments to oxygen, thereby facilitating microbial remineralization of carbon stocks and diminished carbon storage capacity (Barañano et al, 2017; Trevathan‐Tackett et al, ; Macreadie et al, ). Furthermore, even natural disturbances such as wave action and bioturbation by infaunal organisms can result in favorable conditions for microbial degradation of sediment carbon by changing oxygen penetration depths (Thomson, ).…”

Section: Discussionmentioning

confidence: 99%

A Synthesis of Blue Carbon Stocks, Sources, and Accumulation Rates in Eelgrass (Zostera marina) Meadows in the Northeast Pacific

Prentice

Poppe

Lutz

et al. 2020

Global Biogeochemical Cycles

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There is increasing urgency to implement climate change mitigation strategies that enhance greenhouse gas removal from the atmosphere and reduce carbon dioxide (CO2) emissions. Recently, coastal “blue carbon” habitats⁠—mangroves, salt marshes, and seagrass meadows—have received attention for their ability to capture CO2 and store organic carbon (OC), primarily in their sediments. Across habitat types and regions, however, information about the sequestration rates and sources of carbon to local sediments remains sparse. Here we compiled recently obtained estimates of sediment OC stocks and sequestration rates from 139 cores collected from temperate seagrass (Zostera marina) meadows in Alaska, British Columbia, Washington, and Oregon. Across all cores sediment OC content averaged 0.75%. Organic carbon stocks in the top 25 cm and 1 m of the sediment averaged 1,846 and 7,168 g OC m−2, respectively. Carbon sequestration rates ranged from 4.6 to 93.0 g OC m−2 yr−1 and averaged 24.8 g OC m−2 yr−1. Isotopic data from this region suggest that OC in the sediments is largely from noneelgrass sources. In general, these values are comparable to those from other temperate Z. marina meadows, but significantly lower than previously reported values for seagrasses globally. These results further highlight the need for local and species‐level quantification of blue carbon parameters. While temperate eelgrass meadows may not sequester and store as much carbon as seagrass meadows elsewhere, climate policy incentives should still be implemented to protect existing sediment carbon stocks and the other critical ecosystem services associated with eelgrass habitats.

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“…These results suggest the co-occurrence of other factors that are able to drive the microbial response to increased nutrient availability [131]. On the contrary, rising temperatures seem to have a significant effect on the aerobic mineralization of organic carbon, but a negligible effect on both the anaerobic mineralization and the recalcitrant seagrass dead tissue mineralization, as debris of rhizomes and roots [126,[131][132][133][134]. Thus, the aerobic mineralization of exposed buried carbon (as in the case of sediment resuspension by trawling) may reduce the carbon sink capacity of seagrass dead organic matter, through increased microbial abundance and speed-up of the mineralization process [133,134].…”

Section: The Seagrass Holobiontmentioning

confidence: 90%

“…Looking at the ecosystem level, interactions among seagrasses and microorganisms can directly influence large-scale biogeochemical processes, including coastal carbon sequestration [123][124][125][126][127][128][129][130][131][132][133], the so-called blue carbon [124]. Seagrass ecosystems are significant carbon sinks, as both living plant biomass and recalcitrant dead organic matter, and the degradative activity of the sediment microbial communities control the amount of sequestered carbon [128,131].…”

Section: The Seagrass Holobiontmentioning

confidence: 99%

“…Recent studies showed an increased mineralization rate of organic carbon in sediments as a response to eutrophication and warming seawater temperatures. In fact, both eutrophication and warming seawater temperatures may stimulate microbial metabolism and speed-up the mineralization processes, enhancing CO 2 release within the water column [126,129,131,132,134]. Contrasting results were found by investigating whether the nutrient input stimulates the mineralization process in vegetated sediments [129,131].…”

Section: The Seagrass Holobiontmentioning

confidence: 99%

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The Seagrass Holobiont: What We Know and What We Still Need to Disclose for Its Possible Use as an Ecological Indicator

Conte

Rotini

Manfra

et al. 2021

Water

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Microbes and seagrass establish symbiotic relationships constituting a functional unit called the holobiont that reacts as a whole to environmental changes. Recent studies have shown that the seagrass microbial associated community varies according to host species, environmental conditions and the host’s health status, suggesting that the microbial communities respond rapidly to environmental disturbances and changes. These changes, dynamics of which are still far from being clear, could represent a sensitive monitoring tool and ecological indicator to detect early stages of seagrass stress. In this review, the state of art on seagrass holobiont is discussed in this perspective, with the aim of disentangling the influence of different factors in shaping it. As an example, we expand on the widely studied Halophila stipulacea’s associated microbial community, highlighting the changing and the constant components of the associated microbes, in different environmental conditions. These studies represent a pivotal contribution to understanding the holobiont’s dynamics and variability pattern, and to the potential development of ecological/ecotoxicological indices. The influences of the host’s physiological and environmental status in changing the seagrass holobiont, alongside the bioinformatic tools for data analysis, are key topics that need to be deepened, in order to use the seagrass-microbial interactions as a source of ecological information.

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Vulnerability of seagrass blue carbon to microbial attack following exposure to warming and oxygen

Cited by 51 publications

References 73 publications

Global Patterns in Marine Sediment Carbon Stocks

Global Patterns in Marine Sediment Carbon Stocks

A Synthesis of Blue Carbon Stocks, Sources, and Accumulation Rates in Eelgrass (Zostera marina) Meadows in the Northeast Pacific

The Seagrass Holobiont: What We Know and What We Still Need to Disclose for Its Possible Use as an Ecological Indicator

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