Damage to seagrass and seaweed beds in Matsushima Bay, Japan, caused by the huge tsunami of the Great East Japan Earthquake on 11 March 2011

Tsujimoto, Ryo; Terauchi, Genki; Sasaki, Hiroyuki; Sakamoto, Shingo; Sawayama, Shuhei; Sasa, Shuji; Yagi, Hiroshi; Komatsu, Toshimitsu

doi:10.1080/01431161.2016.1249300

Cited by 17 publications

(14 citation statements)

References 27 publications

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“…At a lower spatial resolution, a large-scale mapping is preferred to measure the effects of the natural hazards (in Indian [128] and Japan [144], for instance) or to provide more data for resource inventory with typical works in the lower Alaska Peninsula [136] and Landsat-5 TM in the Eastern Africa coast [165]. Other works involve seagrass mapping from Landsat-8 OLI [145] and [147]; ASTER, SPOT–4, and KOMPSAT–2 [138]; ALOS AVNIR–2 [120] and [152]; ALOS AVNIR–2 and ASTER using leaf area index [132]; Indian remote sensing (IRS) [125] and THEOSdata [135].…”

Section: Background and Methodsmentioning

confidence: 99%

A Review of Remote Sensing Approaches for Monitoring Blue Carbon Ecosystems: Mangroves, Seagrassesand Salt Marshes during 2010–2018

Pham

Xia

et al. 2019

Sensors

113

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Blue carbon (BC) ecosystems are an important coastal resource, as they provide a range of goods and services to the environment. They play a vital role in the global carbon cycle by reducing greenhouse gas emissions and mitigating the impacts of climate change. However, there has been a large reduction in the global BC ecosystems due to their conversion to agriculture and aquaculture, overexploitation, and removal for human settlements. Effectively monitoring BC ecosystems at large scales remains a challenge owing to practical difficulties in monitoring and the time-consuming field measurement approaches used. As a result, sensible policies and actions for the sustainability and conservation of BC ecosystems can be hard to implement. In this context, remote sensing provides a useful tool for mapping and monitoring BC ecosystems faster and at larger scales. Numerous studies have been carried out on various sensors based on optical imagery, synthetic aperture radar (SAR), light detection and ranging (LiDAR), aerial photographs (APs), and multispectral data. Remote sensing-based approaches have been proven effective for mapping and monitoring BC ecosystems by a large number of studies. However, to the best of our knowledge, this is the first comprehensive review on the applications of remote sensing techniques for mapping and monitoring BC ecosystems. The main goal of this review is to provide an overview and summary of the key studies undertaken from 2010 onwards on remote sensing applications for mapping and monitoring BC ecosystems. Our review showed that optical imagery, such as multispectral and hyper-spectral data, is the most common for mapping BC ecosystems, while the Landsat time-series are the most widely-used data for monitoring their changes on larger scales. We investigate the limitations of current studies and suggest several key aspects for future applications of remote sensing combined with state-of-the-art machine learning techniques for mapping coastal vegetation and monitoring their extents and changes.

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Section: Background and Methodsmentioning

confidence: 99%

A Review of Remote Sensing Approaches for Monitoring Blue Carbon Ecosystems: Mangroves, Seagrassesand Salt Marshes during 2010–2018

Pham

Xia

et al. 2019

Sensors

113

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“…The core length was 41 cm. The sampling site MC2 is near an area where Zostera beds flourished before the 2011 tsunami but had not yet recovered in 2016 (Nishimura, ; Sakamaki & Nishimura, ; Tsujimoto et al, ). According to Irizuki et al (), lithofacies of the core MC2‐2 was classified into four units in ascending order, which are Unit I (core depth >15 cm): brownish‐gray sandy mud bed with burrows and shell fragments, Unit II (9–15 cm): dark‐gray to black sandy mud bed (the 2011 tsunami deposits), Unit III (1–9 cm): dark‐gray to black mud bed, and Unit IV (<1 cm): yellowish‐brown mud layer.…”

Section: Methodsmentioning

confidence: 99%

“…Oysters and seaweed have been cultivated in the area since the 1920s (Sakamaki & Nishimura, ). The aquaculture facilities in the bay were seriously damaged by the 2011 tsunami, and they had not yet recovered in 2016 (Nishimura, ; Sakamaki & Nishimura, ; Tsujimoto et al, ). Takagi River discharges into the northern part of Matsushima Bay, and the catchment area is 118.2 km 2 .…”

Section: Geologic and Oceanographic Settingsmentioning

confidence: 99%

Sediments of Matsushima Bay, Northeastern Japan: Insights Gained From 5 Years of Sedimentological Analysis Following the 2011 Tohoku Earthquake‐Tsunami

Ota

Suzuki

Yamaoka

et al. 2019

Geochem Geophys Geosyst

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Matsushima Bay was less affected by the 2011 Tohoku Earthquake Tsunami than other Pacific coastal areas of northeast Japan because of the sheltering effects of islands in the bay mouth. To understand the recovery from the 2011 tsunami of benthic environments in Matsushima Bay, we conducted surveys of the geochemical properties of surface sediments over 5 years following the earthquake and compared them to sedimentary data before the earthquake. Before the tsunami, the mud fraction (<63‐μm size) proportion of the surface sediments varied over a wide range, whereas after the tsunami, the mud content range was relatively narrow. During 2012–2015, the mud content was linearly correlated with the total organic carbon (TOC) content, but the slope of the relationship differed from that before the tsunami. The tightly coupled mud‐TOC relationship and the almost constant C/N ratios in the surface sediments suggest that the bay sediments were resuspended and transported by the tsunami. In addition, loss of some organic matter sources in the bay may partly account for the uniform C/N ratios. By 2016, the slope of the mud‐TOC relationship was almost the same as the pretsunami value, but the C/N ratios remained constant. These results suggest that ecosystems and biogeochemical cycles in the bay had not yet fully recovered their pretsunami state. Trace element compositions of core samples indicated that sediment sources were little changed by the tsunami, probably because islands in the mouth of the bay reduced sediment transport into the bay from distant sources.

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“…The Biodiversity Center of Japan (2015) reported that the area of seagrass along the Sanriku Coast before the tsunami had decreased during the 2012–2014 monitoring period. Consequently, mapping seagrass meadows is a very practical method to monitor the recovery process in coastal ecosystems after tsunamis, although only a few studies have attempted this monitoring (e.g., Komatsu et al, 2018b ; Tsujimoto et al, 2016 ). Since bottom depths were changed by co-seismic land subsidence and post-seismic uplift after the tsunami ( Geospatial Information Authority of Japan, 2020 ), the lower depth limits of seagrass meadows limited by light availability enough for survivals of seagrasses ( Duarte, 1991 ; Komatsu & Tatsukawa, 1998 ; Sakanishi & Komatsu, 2017 ) are also influenced by a height of water column above the bottom depending on the bottom depth.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Roelfsema et al (2014) used a semi-automated object-based image analysis on WorldView-2, IKONOS, and Quickbird-2 multispectral satellite images at 2.4–4.0 m resolutions to map seagrass cover, species, and biomass in the Eastern Banks of Moreton Bay, Australia. Tsujimoto et al (2016) used GeoEye-1 and WorldView-2 multispectral satellite images at 2.0 m resolution to map seagrass meadows before and after the 2011 tsunami in Matsushima Bay on the Sanriku Coast. Aquaculture facilities have also been mapped via high-resolution satellite remote sensing.…”

Section: Introductionmentioning

confidence: 99%

Monitoring oyster culture rafts and seagrass meadows in Nagatsura-ura Lagoon, Sanriku Coast, Japan before and after the 2011 tsunami by remote sensing: their recoveries implying the sustainable development of coastal waters

Murata

Hara

Yonezawa

et al. 2021

PeerJ

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Background Coastal ecosystems are blue infrastructures that support coastal resources and also aquaculture. Seagrass meadows, one of coastal ecosystems, provide substrates for epiphytic diatoms, which are food resources for cultured filter feeder organisms. Highly intensive coastal aquaculture degrades coastal environments to decrease seagrass meadows. Therefore, efficient aquaculture management and conservation of seagrass meadows are necessary for the sustainable development of coastal waters. In ria-type bays, non-feeding aquaculture of filter feeders such as oysters, scallops, and ascidians are actively practiced along the Sanriku Coast, Japan. Before the 2011 Great East Japan Earthquake, the over-deployment of oyster culture facilities polluted the bottom environment and formed an hypoxic bottom water layer due to the organic excrements from cultured oysters. The tsunami in 2011 devastated the aquaculture facilities and seagrass meadows along the Sanriku Coast. We mapped the oyster culture rafts and seagrass meadows in Nagatsura-ura Lagoon, Sanriku Coast before and after the tsunami and monitored those and environments after the tsunami by field surveys. Methods We conducted field surveys and monitored the environmental parameters in Nagatsura-ura Lagoon every month since 2014. We used high-resolution satellite remote sensing images to map oyster culture rafts and seagrass meadows at irregular time intervals from 2006 to 2019 in order to assess their distribution. In 2019, we also used an unmanned aerial vehicle to analyze the spatial variability of the position and the number of ropes suspending oyster clumps beneath the rafts. Results In 2013, the number and distribution of the oyster culture rafts had been completely restored to the pre-tsunami conditions. The mean area of culture raft increased after the tsunami, and ropes suspending oyster clumps attached to a raft in wider space. Experienced local fishermen also developed a method to attach less ropes to a raft, which was applied to half of the oyster culture rafts to improve oyster growth. The area of seagrass meadows has been expanding since 2013. Although the lagoon had experienced frequent oyster mass mortality events in summer before the tsunami, these events have not occurred since 2011. The 2011 earthquake and tsunami deepened the sill depth and widened the entrance to enhance water exchange and improve water quality in the lagoon. These changes brought the expansion of seagrass meadows and reduction of mass mortality events to allow sustainable oyster culture in the lagoon. Mapping and monitoring of seagrass meadows and aquaculture facilities via satellite remote sensing can provide clear visualization of their temporal changes. This can in turn facilitate effective aquaculture management and conservation of coastal ecosystems, which are crucial for the sustainable development of coastal waters.

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Damage to seagrass and seaweed beds in Matsushima Bay, Japan, caused by the huge tsunami of the Great East Japan Earthquake on 11 March 2011

Cited by 17 publications

References 27 publications

A Review of Remote Sensing Approaches for Monitoring Blue Carbon Ecosystems: Mangroves, Seagrassesand Salt Marshes during 2010–2018

A Review of Remote Sensing Approaches for Monitoring Blue Carbon Ecosystems: Mangroves, Seagrassesand Salt Marshes during 2010–2018

Sediments of Matsushima Bay, Northeastern Japan: Insights Gained From 5 Years of Sedimentological Analysis Following the 2011 Tohoku Earthquake‐Tsunami

Monitoring oyster culture rafts and seagrass meadows in Nagatsura-ura Lagoon, Sanriku Coast, Japan before and after the 2011 tsunami by remote sensing: their recoveries implying the sustainable development of coastal waters

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