scholarly journals Variation of carbon contents in eelgrass ( Zostera marina ) sediments implied from depth profiles

2019 ◽  
Vol 15 (6) ◽  
pp. 20180831 ◽  
Author(s):  
Theodor Kindeberg ◽  
Emilia Röhr ◽  
Per-Olav Moksnes ◽  
Christoffer Boström ◽  
Marianne Holmer
Keyword(s):  
Organic Carbon ◽  
Zostera Marina ◽  
Large Scale ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Depth Profiles ◽  
Seagrass Meadows ◽  
Spatio Temporal ◽  
Organic Carbon Storage ◽  
Eelgrass Beds

Seagrass meadows are able to store significant amounts of organic carbon in their underlying sediment, but global estimates are uncertain partly owing to spatio-temporal heterogeneity between and within areas and species. In order to provide robust estimates, there is a need to better understand the fate of, and mechanisms behind, organic carbon storage. In this observational study, we analyse a suite of biotic and abiotic parameters in sediment cores from 47 different eelgrass ( Zostera marina ) beds spanning the distributional range of the Northern Hemisphere. Depth profiles of particulate organic carbon (POC) revealed three patterns of vertical distribution where POC either increased, decreased or showed no pattern with sediment depth. These categories exhibited distinct profiles of δ 13 C and C:N ratios, where high POC profiles had a proportionally larger storage of eelgrass-derived material whereas low POC profiles were dominated by phytoplanktonic and macroalgal material. However, high POC did not always translate into high carbon density. Nevertheless, this large-scale dataset provides evidence that the variability in organic matter source in response to natural and anthropogenic environmental changes affects the potential role of eelgrass beds as POC sinks, particularly where eelgrass decline is observed.

scholarly journals Seagrass community-level controls over organic carbon storage are constrained by geophysical attributes within meadows of Zanzibar, Tanzania

2018 ◽  
Vol 15 (14) ◽  
pp. 4609-4626 ◽  
Author(s):  
Elizabeth Fay Belshe ◽  
Dieuwke Hoeijmakers ◽  
Natalia Herran ◽  
Matern Mtolera ◽  
Mirta Teichberg
Keyword(s):  
Organic Carbon ◽  
Plant Traits ◽  
Sediment Cores ◽  
Belowground Biomass ◽  
Shoot Density ◽  
Seagrass Meadows ◽  
Seagrass Community ◽  
Seagrass Ecosystems ◽  
Organic Carbon Storage ◽  
Thalassodendron Ciliatum

Abstract. The aim of this work was to explore the feasibility of using plant functional traits to identify differences in sediment organic carbon (OC) storage within seagrass meadows. At 19 sites within three seagrass meadows in the coastal waters of Zanzibar, Tanzania, species cover was estimated along with three community traits hypothesized to influence sediment OC storage (above and belowground biomass, seagrass tissue nitrogen content, and shoot density). Sediments within four biogeographic zones (fore reef, reef flat, tidal channel, and seagrass meadow) of the landscape were characterized, and sediment cores were collected within seagrass meadows to quantify OC storage in the top 25 cm and top meter of the sediment. We identified five distinct seagrass communities that had notable differences in the plant traits, which were all residing within a thin veneer (ranging from 19 to 78 cm thick) of poorly sorted, medium to coarsely grained carbonate sands on top of carbonate rock. One community (B), dominated by Thalassodendron ciliatum, contained high amounts of above (972±74 g DW m−2) and belowground (682±392 g DW m−2) biomass composed of low-elemental-quality tissues (leaf C : N = 24.5; rhizome C : N = 97). While another community (C), dominated by small-bodied ephemeral seagrass species, had significantly higher shoot density (4178 shoots m−2). However, these traits did not translate into differences in sediment OC storage and across all communities the percentage of OC within sediments was similar and low (ranging from 0.15 % to 0.75 %), as was the estimated OC storage in the top 25 cm (14.1±2.2 Mg C ha−1) and top meter (33.9±7.7 Mg C ha−1) of sediment. These stock estimates are considerably lower than the global average (194.2±20.2 Mg C ha−1) reported for other seagrass ecosystems and are on the lower end of the range of estimates reported for the tropical Indo-Pacific bioregion (1.9 to 293 Mg C ha−1). The uniformly low OC storage across communities, despite large inputs of low-quality belowground tissues in community B, indicates that the geophysical conditions of the coarse, shallow sediments at our sites were not conducive to OC stabilization and outweighed any variation in the quantity or quality of seagrass litter inputs. These results add to a growing body of evidence showing that geophysical conditions of the sediment modulate the importance of plant traits in regards to retention of OC within blue carbon ecosystems and cautions against the use of plant traits as a proxy for sediment OC storage across all seagrass ecosystems.

scholarly journals Late Quaternary paleoenvironment of the Ross Sea continental shelf, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 275-280 ◽  
Author(s):  
Akira Nishimura ◽  
Toru Nakasone ◽  
Chikara Hiramatsu ◽  
Manabu Tanahashi
Keyword(s):  
Organic Carbon ◽  
Marine Environment ◽  
Environmental Changes ◽  
Ross Sea ◽  
Late Quaternary ◽  
Sedimentary Environment ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Accelerator Mass Spectrometer

Based on sedimenlological and micropaleontological work on three sediment cores collected at about 167° Ε in the western Ross Sea, Antarctica, and accelerator mass spectrometer l4C ages of organic carbon, we have reconstructed environmental changes in the area during the late Quaternary. Since 38 ka BP at latest, this area was a marine environment with low productivity. A grounded ice sheet advanced and loaded the sediments before about 30-25 ka BP. After 25 ka BP, the southernmost site (76°46'S) was covered by floating ice (shelf ice), preventing deposition of coarse terrigenous materials and maintaining a supply of diatom tests and organic carbon until 20 ka BP. The northernmost site (74°33'S) was in a marine environment with a moderate productivity influenced by shelf ice/ice sheet after about 20 ka BP. Since about 10 ka BP, a sedimentary environment similar to the present-day one has prevailed over this area.

Ten years of conservation efforts enhance seagrass cover and carbon storage in Thailand

2018 ◽  
Vol 61 (5) ◽  
pp. 441-451 ◽  
Author(s):  
Ekkalak Rattanachot ◽  
Milica Stankovic ◽  
Supaphon Aongsara ◽  
Anchana Prathep
Keyword(s):  
Organic Carbon ◽  
Carbon Storage ◽  
Seagrass Meadow ◽  
Seagrass Meadows ◽  
Rate Of Increase ◽  
Southern Thailand ◽  
Seagrass Cover ◽  
Conservation Projects ◽  
Organic Carbon Storage ◽  
Total Coverage

Abstract Seagrasses are known as engineering ecosystems that play important roles in coastal environments. Globally, seagrass areas have been declining, and many conservation projects have been carried out to prevent further decline. The goal of this work was to determine how successful conservation efforts have been in a seagrass meadow at Koh Tha Rai in the Nakhon Si Thammarat Province of southern Thailand in terms of meadow extent, coverage and organic carbon storage. A study was conducted in 2017 and compared to a previous study from 2006 to determine the effects of the various conservation efforts devoted to this area. The results show that the total seagrass area increased by 0.7 ha with a rate of increase of approximately 0.06 ha year−1. The total coverage of seagrass increased by approximately 3 times. The organic carbon in existing seagrass meadows (2006) was 53.35 Mg ha−1, while growth was 32.34 Mg ha−1 in the areas of new seagrass. Moreover, the total organic carbon storage in the sediment increased by 26.86 MgC from 2006 to 2017 (from 211.60 MgC to 235.46 MgC). In conclusion, this study demonstrated the importance of successful conservation efforts in terms of increasing seagrass meadow areas, seagrass coverage and carbon storage within the meadow.

scholarly journals Blue Carbon stock in Zostera noltei meadows at Ria de Aveiro coastal lagoon (Portugal) over a decade

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ana I. Sousa ◽  
José Figueiredo da Silva ◽  
Ana Azevedo ◽  
Ana I. Lillebø
Keyword(s):  
Coastal Lagoon ◽  
Large Scale ◽  
Management Plan ◽  
Blue Carbon ◽  
Temporal Shift ◽  
Ria De Aveiro ◽  
Seagrass Meadows ◽  
Zostera Noltei ◽  
C Stock ◽  
Spatio Temporal

Abstract This work assessed the Blue Carbon (C) stock in the seagrass meadows (Zostera noltei) of Ria de Aveiro coastal lagoon (Portugal), and evaluated its spatio-temporal trend over the 2003–2005 to 2013–2014 period. Zostera noltei spatial distribution, restricted to intertidal areas in 2014, was mapped by remote sensing using an unmanned aerial vehicle (UAV) and aerial photography. Zostera noltei biomass was also monitored in situ over a year and its Blue C stock was estimated. By 2014, intertidal meadows covered an area of 226 ± 4 ha and their Blue C stock ranged from 227 ± 6 to 453 ± 13 Mg C. Overall, Ria de Aveiro Z. noltei intertidal meadows increased in extent over the 2003–2005 to 2013–2014 period, corroborating the recent declining trend reversal observed in Europe and contrary to the global decline trend. This spatio-temporal shift might be related to a natural adjustment of the intertidal meadows to past human intervention in Ria de Aveiro, namely large-scale dredging activities, particularly in the 1996–1998 period, combined with the more accurate assessment performed in 2014 using the UAV. This recovery contributes to the effective increase of the Blue C stock in Ria de Aveiro and, ultimately, to supporting climate regulation and improving ecosystem health. However, major dredging activities are foreseen in the system’s management plan, which can again endanger the recovery trend of Z. noltei intertidal meadows in Ria de Aveiro.

scholarly journals Geophysical constraints for organic carbon sequestration capacity of Zostera marina seagrass meadows and surrounding habitats

2017 ◽  
Vol 62 (3) ◽  
pp. 954-972 ◽  
Author(s):  
Toshihiro Miyajima ◽  
Masakazu Hori ◽  
Masami Hamaguchi ◽  
Hiromori Shimabukuro ◽  
Goro Yoshida
Keyword(s):  
Carbon Sequestration ◽  
Organic Carbon ◽  
Zostera Marina ◽  
Seagrass Meadows ◽  
Organic Carbon Sequestration

A field-scale laboratory to study particulate transport from river source to marine sink: Bute Inlet (Canada)

2021 ◽  
Author(s):  
Sophie Hage ◽  
Sanem Acikalin ◽  
Lewis Bailey ◽  
Matthieu Cartigny ◽  
Michael Clare ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Large Scale ◽  
Sediment Cores ◽  
Past Research ◽  
Transport Processes ◽  
Small Scale ◽  
Turbidity Currents ◽  
Upstream Migration ◽  
Submarine Channel ◽  
The Impact

<p>It is often assumed that particles produced on land (e.g., sediment, pollutants and organic matter) are transported through watersheds to a terminal sediment sink at the seashore. However, terrestrial particles can continue their journey offshore via submarine channels, accumulating in abyssal plains of the oceans. Offshore sediment transport processes are key controls on the burial of organic carbon and the distribution of benthic food, yet they are challenging to study due to the difficulty of capturing usually short duration events within large-scale systems at great ocean depths. Fjords are sufficiently small scale to enable their submarine channel systems to be studied from river source to terminal sink on seafloor fans. Bute Inlet is an up to 650 m deep fjord in British Columbia, Canada. The Homathko and Southgate rivers both feed Bute Inlet with freshwater and terrestrial sediment. A large landslide occurred on 28<sup>th</sup> November 2020, which caused a Glacial-Lake Outburst Flood (GLOF) which breached a moraine-dam and transported huge volumes of material through the Southgate valley and into Bute Inlet. The impact of this recent event on the submarine system in Bute is, for now, poorly constrained but ongoing work is exploring the impact of this major event on the Inlet. Bute Inlet is one of the most studied fjords worldwide, with a range of offshore campaigns that have been conducted during the last seventy years, providing an unprecedented background dataset and thus opportunity to explore what impact a large magnitude, low frequency terrestrial event had on the submarine system. This presentation will provide an overview of the past research conducted on the Bute submarine channel system, under more usual river discharge conditions and compare this background context to the recent GLOF event.</p><p>Previous studies have revealed that the floor of the Inlet is characterized by a 40 km long submarine channel formed by submarine avalanches of sediment (turbidity currents) that can be up to 30 m thick and reach velocities of up to 6.5 m/s. Based on time-lapse bathymetric mapping over 10 years, the evolution of this channel is known to be controlled by the fast (100 to 450 m/yr) upstream migration of 5 to 30 m high steps (called knickpoints) in the channel floor. Sediment cores reveal that the channel floor and proximal lobe are dominated by sand and up to 3 % of total organic carbon in the form of young woody debris. Research in Bute Inlet has thus allowed submarine flow processes, seafloor morphology and deposits to be linked in unprecedented detail. Using those past results as a baseline, new data collected after the GLOF will be crucial for testing the impact of high-magnitude catastrophic events on a marine system and the ultimate sink for the terrestrial material. Understanding what impact the GLOF had on the usual seafloor processes has direct implications for the preservation of benthic communities living in the fjord and for the global carbon cycle.</p>

The distribution of large floating seagrass (Zostera marina) clumps in northern temperate zones of Bohai Bay in the Bohai Sea, China

2018 ◽  
Author(s):  
Xu Min ◽  
Zhou Yi ◽  
Zhang Tao ◽  
Zhang Yun-Ling
Keyword(s):  
Zostera Marina ◽  
Large Scale ◽  
Bohai Sea ◽  
Atlantic Cod ◽  
Marine Organisms ◽  
Future Research ◽  
Bohai Bay ◽  
Strombus Gigas ◽  
The Bohai Sea ◽  
Seagrass Meadows

AbstractSeagrass meadows (Zostera marina) are important coastal ecosystems with high levels of productivity and biodiversity. They are subject to considerable natural and anthropogenic threats in China, such as oyster and snail aquaculture, wastewater discharge, electro-fishing, shellfish collection, typhoons and floods. When seagrass communities are disturbed, they can become removed from the sediment and converted into floating clumps, which then serve as marine hot spots attracting a variety of marine organisms that then inhabit them. They are important nursery habitats for many economic fish such as red drum (Sciaenops ocellatus), Atlantic cod (Gadus morhua), queen conch (Strombus gigas), and blue crab (Callinectes sapidus). Thus, it is necessary to study the distribution and biological characteristics of these floating seagrass clumps. In September 2016 we observed large scale floating Z. marina clumps in the northernmost area of Bohai Bay (38°57’1.14”−39° 0’41.28” N, 118°45’23.22”−118°47’6.96” E), in the Bohai Sea, China. We observed characteristics that precluded their origination from the nearby Caofeidian seagrass meadows. Two research cruises were undertaken, during which we did not observe other marine organisms accompanying these floating Z. marina clumps. The dominant frond lengths were 40–50 cm, with less than 5% of the total number of fronds found in larger size categories (80–90 and 90–100 cm). We aim to pursue future research into the breakdown and dislodgement characteristics of Z. marina clumps and the processes whereby they sink and integrate with the sediment.

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