scholarly journals Long-Term Changes in the Unique and Largest Seagrass Meadows in the Bohai Sea (China) Using Satellite (1974–2019) and Sonar Data: Implication for Conservation and Restorationc

2021 ◽  
Vol 13 (5) ◽  
pp. 856
Author(s):  
Shaochun Xu ◽  
Shuai Xu ◽  
Yi Zhou ◽  
Shidong Yue ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Bohai Sea ◽  
Land Reclamation ◽  
Landsat Imagery ◽  
Northern China ◽  
Physical Damage ◽  
Error Matrix ◽  
The Bohai Sea ◽  
Seagrass Meadows ◽  
Sea Reclamation

Seagrass meadows play critical roles in supporting a high level of biodiversity but are continuously threatened by human activities, such as sea reclamation. In this study, we reported on a large seagrass (Zostera marina L.) meadow in Caofeidian shoal harbor in the Bohai Sea of northern China. We evaluated the environmental impact of sea reclamation activities using Landsat imagery (1974–2019) by mapping seagrass meadow distribution changes. ISODATA was adopted for the unsupervised classification and mapping of seagrass beds. The error matrix developed using the in situ data obtained from acoustic surveys for Landsat 8OLI image classification was 87.20% accurate. The maps showed rapidly increasing changes in seagrass meadows as the amount of reclaimed land increased. Some seagrass meadows experienced large-scale changes, and sea reclamation has been suggested as the main factor responsible for habitat loss, which results from physical damage, excessive sedimentation, and increased turbidity caused by reclamation. In addition, habitat degradation may have resulted from three storm surges induced by typhoons in 1992–1998. Fortunately, land reclamation, forming an artificial “longshore bar”, buffers seagrass meadows from wave actions, providing relatively sheltered conditions, which has allowed a large habitat increase since 2012. These were the largest eelgrass meadows (3,217.32 ha), with a peripheral area of ~100 km2, in the Bohai Sea of northern China in 2019. However, the existing largest eelgrass beds in China are threatened by trawling, clam harvesting (especially clam sucking), channel dredging, and culture pond construction. Our work will help coastal managers monitor the environmental impacts of reclamation activities on seagrass meadows on a large spatio-temporal scale and will also provide information for seagrass restoration using artificial “longshore bars”.

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.

Autumn Migration of Mythimna separata (Lepidoptera: Noctuidae) over the Bohai Sea in Northern China

2008 ◽  
Vol 37 (3) ◽  
pp. 774-781 ◽  
Author(s):  
Hong-Qiang Feng ◽  
Xin-Cheng Zhao ◽  
Xian-Fu Wu ◽  
Bo Wu ◽  
Kong-Ming Wu ◽  
...  
Keyword(s):  
Bohai Sea ◽  
Northern China ◽  
Autumn Migration ◽  
Mythimna Separata ◽  
The Bohai Sea ◽  
Lepidoptera Noctuidae

scholarly journals Large-scale patterns in the community structure and biodiversity of freeliving nematodes in the Bohai Sea, China

2001 ◽  
Vol 81 (5) ◽  
pp. 755-763 ◽  
Author(s):  
Y. Guo ◽  
P.J. Somerfield ◽  
R.M. Warwick ◽  
Z. Zhang
Keyword(s):  
Community Structure ◽  
Environmental Variables ◽  
Large Scale ◽  
Bohai Sea ◽  
Yellow River ◽  
River Mouth ◽  
Sediment Surface ◽  
Similar Species ◽  
Taxonomic Distinctness ◽  
The Bohai Sea

Freeliving marine nematodes were sampled on two occasions from an extensive grid of 20 stations in the Bohai Sea and its approaches. Differences within stations between sampling periods were small, resulting from small changes in abundance of dominant species. Differences between stations were significant, and were used to cluster stations into groups with similar species composition. These station groupings revealed a weak faunal gradient leading from the mouth of the Huanghe (Yellow River) to the Bohai Strait. Analyses relating faunal composition to environmental variables showed that there were significant differences in environmental variables between faunally-defined groups of stations. The variables most closely correlated with community structure were silt/clay and sand, depth, phaeopigment concentrations below the sediment surface, organic content and arsenic. These reflect natural processes within the Bohai Sea. A suite of univariate measures were related to distance from the river mouth, with a major discontinuity about 120 km into the Bohai Sea. Comparison of values of the biodiversity measures average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) suggest that the meiobenthos of the Bohai Sea as a whole is not under major pollution stress.

Sea-level changes in the Bohai Sea, northern China, constrained by coastal loess accumulation over the past 200 ka

2022 ◽  
Vol 277 ◽  
pp. 107368
Author(s):  
Shuangwen Yi ◽  
Lin Zeng ◽  
Zhiwei Xu ◽  
Yao Wang ◽  
Xianyan Wang ◽  
...  
Keyword(s):  
Sea Level ◽  
Bohai Sea ◽  
Northern China ◽  
Sea Level Changes ◽  
The Bohai Sea ◽  
The Past

Satellite image analysis reveals changes in seagrass beds at Van Phong Bay, Vietnam during the last 30 years

2020 ◽  
Vol 33 ◽  
pp. 4
Author(s):  
Trong-Thach Vo ◽  
Khin Lau ◽  
Lawrence M. Liao ◽  
Xuan-Vy Nguyen
Keyword(s):  
Image Analysis ◽  
Land Reclamation ◽  
Satellite Image ◽  
Distribution Data ◽  
Seagrass Beds ◽  
Error Matrix ◽  
Seagrass Meadows ◽  
Negative Impacts ◽  
Biological Performance ◽  
Satellite Image Analysis

Seagrass meadows are fragile ecosystems in the coastal zone. Natural disasters, land reclamation and various human activities seem to exert negative impacts on the distribution and biological performance of seagrass beds in Vietnam. In this present study, satellite Landsat TM/OLI image analysis was applied to determine changes in seagrass distribution at Van Phong Bay, Vietnam in the last 30 years. The maximum likelihood decision rule was used to extract seagrass bed distribution data. The error matrix using the in situ reference data for HLM image classification was 81–95% accurate, and Kappa coefficients were between 0.72 and 0.91. The results indicated that 186.2 ha (or 35.8%) of the original seagrass beds were lost in the last three decades at Van Phong Bay, and decline in each specific site may have been due to different causes. Typhoons may have caused the loss of seagrass beds at open-sea sites whereas aquaculture activities, excavation and terrigenous obliteration may have caused such losses in protected sites.

A new species of the genus Austinogebia Ngoc-Ho, 2001 (Crustacea, Decapoda, Gebiidea, Upogebiidae) from northern China

Zootaxa ◽  
2012 ◽  
Vol 3243 (1) ◽  
pp. 59 ◽  
Author(s):  
WENLIANG LIU ◽  
RUIYU LIU
Keyword(s):  
New Species ◽  
Bohai Sea ◽  
Northern China ◽  
Lower Margin ◽  
The Bohai Sea ◽  
A New Species

A new species of the genus Austinogebia Ngoc-Ho, 2001, A. monospina n. sp., collected from the Bohai Sea and theYellow Sea, is described and illustrated. It is closely allied to A. spinifrons (Haswell, 1881) but differs markedly in the rostral ornamentation, with one infrarostral spine and the unarmed lower margin of antennal peduncle.

Nocturnal migration of dragonflies over the Bohai Sea in northern China

2006 ◽  
Vol 31 (5) ◽  
pp. 511-520 ◽  
Author(s):  
HONG-QIANG FENG ◽  
KONG-MING WU ◽  
YUN-XIA NI ◽  
DENG-FA CHENG ◽  
YU-YUAN GUO
Keyword(s):  
Bohai Sea ◽  
Northern China ◽  
The Bohai Sea ◽  
Nocturnal Migration

Seasonal Migration of Apolygus lucorum (Hemiptera: Miridae) Over the Bohai Sea in Northern China

2014 ◽  
Vol 107 (4) ◽  
pp. 1399-1410 ◽  
Author(s):  
Xiaowei Fu ◽  
Yongqiang Liu ◽  
Chao Li ◽  
Yanhui Lu ◽  
Yunhe Li ◽  
...  
Keyword(s):  
Bohai Sea ◽  
Northern China ◽  
Seasonal Migration ◽  
The Bohai Sea ◽  
Apolygus Lucorum
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