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.

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”.

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

PLoS ONE ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. e0201574
Author(s):  
Xu Min ◽  
Zhou Yi ◽  
Song Xiao-Jing ◽  
Zhang Yun-Ling ◽  
Zhang Hai-Peng
Keyword(s):  
Zostera Marina ◽  
Bohai Sea ◽  
Bohai Bay ◽  
The Bohai Sea

scholarly journals Storm Surges in the Bohai Sea: The Role of Waves and Tides

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1509
Author(s):  
Yuanyi Li ◽  
Huan Feng ◽  
Guillaume Vigouroux ◽  
Dekui Yuan ◽  
Guangyu Zhang ◽  
...  
Keyword(s):  
Storm Surge ◽  
Bohai Sea ◽  
Storm Surges ◽  
Wave Force ◽  
Laizhou Bay ◽  
Bohai Bay ◽  
Coastal Regions ◽  
The Bohai Sea ◽  
Tidal Phase ◽  
Set Up

A storm surge is a complex phenomenon in which waves, tide and current interact. Even though wind is the predominant force driving the surge, waves and tidal phase are also important factors that influence the mass and momentum transport during the surge. Devastating storm surges often occur in the Bohai Sea, a semi-enclosed shallow sea in North China, due to extreme storms. However, the effects of waves on storm surges in the Bohai Sea have not been quantified and the mechanisms responsible for the higher surges that affect part of the Bohai Sea have not been thoroughly studied. In this study, we set up a storm surge model, considering coupled effects of tides and waves on the surges. Validation against measured data shows that the coupled model is capable of simulating storm surges in the Bohai Sea. The simulation results indicate that the longshore currents, which are induced by the large gradient of radiation stress due to wave deformation, are one of the main contributors to the higher surges occurring in some coastal regions. The gently varying bathymetry is another factor contributing to these surges. With such bathymetry, the wave force direction is nearly uniform, and pushes a large amount of water in that direction. Under these conditions, the water accumulates in some parts of the coast, leading to higher surges in nearby coastal regions such as the south coast of the Bohai Bay and the west and south coasts of the Laizhou Bay. Results analysis also shows that the tidal phase at which the surge occurs influences the wave–current interactions, and these interactions are more evident in shallow waters. Neglecting these interactions can lead to inaccurate predictions of the storm surges due to overestimation or underestimation of wave-induced set-up.

scholarly journals Spatio-temporal characteristics of the sea-ice volume of the Bohai Sea, China, in winter 2009/10

2013 ◽  
Vol 54 (62) ◽  
pp. 97-104 ◽  
Author(s):  
Chengyu Liu ◽  
Wei Gu ◽  
Jinlong Chao ◽  
Lantao Li ◽  
Shuai Yuan ◽  
...  
Keyword(s):  
Sea Ice ◽  
Bohai Sea ◽  
Shortwave Radiation ◽  
Laizhou Bay ◽  
Bohai Bay ◽  
Temporal Characteristics ◽  
The Bohai Sea ◽  
Ice Volume ◽  
Radiation Theory ◽  
Spatio Temporal

AbstractTo investigate the spatio-temporal characteristics of sea-ice resource, we used sea-ice volume to measure the amount of sea-ice resource in the Bohai Sea, China. The sea-ice area was extracted from Advanced Very High Resolution Radiometer (AVHRR) remote-sensing images using the zonal threshold method. The sea-ice thickness was estimated using a sea-ice model based on shortwave radiation theory and field measurements. The spatio-temporal characteristics of sea-ice volume were then analysed using GIS technology. The results indicate that the Bohai Sea experienced two sea-ice volume peaks in winter 2009/10. The largest sea-ice volume was in Liaodong Bay (∼80.26% of the entire sea-ice volume of the Bohai Sea). Bohai Bay had the second largest ice volume, and Laizhou Bay the smallest. The relationship between sea-ice volume and distance from shore is essentially exponential. The proportion of total sea-ice volume that is 0–10 km from shore is ∼42.43%, whereas the proportion that is 100–110 km from shore is only 0.002%.

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 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.

Estimating submarine groundwater discharges of the Bohai Sea, China using radium, hydrogen and oxygen isotopes and salinity

2020 ◽  
Author(s):  
Hailong Li ◽  
Xiaolang Zhang ◽  
Xuejing Wang ◽  
Kai Xiao ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Steady State ◽  
Mass Balance ◽  
River Water ◽  
Bohai Sea ◽  
Balance Model ◽  
Laizhou Bay ◽  
Bohai Bay ◽  
Fresh Groundwater ◽  
The Bohai Sea ◽  
Submarine Groundwater

<p>With an area of about 77,000 km<sup>2</sup>, the Bohai Sea includes three bays: Laizhou Bay, Bohai Bay and Liaodong Bay. In this study, <sup>228</sup>Ra, δD, δ<sup>18</sup>O and salinity data were collected from surface seawater in the entire Bohai Sea, river water, and groundwater along its coastline in August 2017. Based on the spatial distributions of δD, δ<sup>18</sup>O, and salinity in surface water in the entire Bohai Sea and δD-salinity relations, the marine hydrological processes were investigated and the members of river water and groundwater for δD and δ<sup>18</sup>O were determined. The steady-state mass-balance models of δD, δ<sup>18</sup>O and salinity are given and used to estimate submarine fresh groundwater discharges and the flushing times of the entire Bohai Sea and its three bays. Based on the results of the flushing times, the steady-state mass-balance model of <sup>228</sup>Ra is used to estimate submarine groundwater discharges of the entire Bohai Sea and its three bays.</p>

scholarly journals General Concerns Life-Cycle Design of Economical Ice-Resistant Structures in the Bohai Sea

2017 ◽  
Vol 24 (s2) ◽  
pp. 164-171
Author(s):  
Da-yong Zhang ◽  
Song-song Yu ◽  
Qian-jin Yue
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Design Theory ◽  
Bohai Sea ◽  
Cost Effective ◽  
Bohai Bay ◽  
Offshore Platforms ◽  
The Bohai Sea ◽  
Life Cycle Design ◽  
Whole Life Cycle

Abstract In China, the oil and natural gas resources of Bohai Bay are mainly marginal oil fields. It is necessary to build both iceresistant and economical offshore platforms. However, there are many risks during the life cycle of offshore platforms due to the imperfect preliminary design for the Bohai Sea economical ice-resistant structures. As a result, the whole life-cycle design should be considered, including plan, design, construction, management and maintenance design. Based on the demand of existing codes and research of the basic design, structural ice-resistant performance and the reasonable management and maintenance, the life-cycle design theory is discussed. It was concluded that the life-cycle cost-effective optimum design proposed will lead to a minimum risk.

scholarly journals Suitability of locations in the Bohai Sea, China, for the exploitation of sea ice as a freshwater resource

2013 ◽  
Vol 54 (62) ◽  
pp. 267-272 ◽  
Author(s):  
Lantao Li ◽  
Wei Gu ◽  
Chengyu Liu ◽  
Yingjun Xu ◽  
Jinlong Chao ◽  
...  
Keyword(s):  
Sea Ice ◽  
Bohai Sea ◽  
Mining Area ◽  
Bohai Bay ◽  
Liaodong Bay ◽  
Gis Technology ◽  
The Bohai Sea ◽  
Freshwater Resource ◽  
The Status ◽  
Technological Level

AbstractBased on recent studies on sea ice and newly developed technologies, this paper examines the requirements and environmental factors for exploitation of sea ice as a freshwater resource. Considering the ‘mining’ of sea ice, the suitability of locations in the Bohai Sea, China, for exploitation was analysed and evaluated using GIS technology. The ice must be >10 cm thick, the intertidal zone must be narrow and the ‘mining’ area must have a water depth of at least 2 m. The sea areas with feasible resources are located mainly in the nearshore area of northern Liaodong Bay and in a narrow and long area along the coast of Bohai Bay. Most coastal areas of northern Liaodong Bay have favourable conditions, while Bohai Bay is widely constrained by unsuitable conditions. According to the status of the resources and the coastal environment conditions, the eastern and western coasts of northern Liaodong Bay are the most suitable areas for exploitation at the current technological level.

scholarly journals Geosynchronous Satellite GF-4 Observations of Chlorophyll-a Distribution Details in the Bohai Sea, China

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5471
Author(s):  
Lina Cai ◽  
Juan Bu ◽  
Danling Tang ◽  
Minrui Zhou ◽  
Ru Yao ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Bohai Sea ◽  
Seawater Temperature ◽  
Remote Sensing Data ◽  
Geosynchronous Orbit ◽  
Laizhou Bay ◽  
Bohai Bay ◽  
The Bohai Sea ◽  
Dynamic Factors ◽  
Chla Concentration

We analyzed the distribution of chlorophyll-a (Chla) in the Bohai Sea area based on data from the geosynchronous orbit optical satellite Gaofen-4 (GF-4), which was launched in 2015, carrying a panchromatic multispectral sensor (PMS). This is the first time the geosynchronous orbit optical satellite GF-4 remote-sensing data has been used in China to detect the Chla change details in the Bohai Sea. A new GF-4 retrieved model was established based on the relationship between in situ Chla value and the reflectance combination of 2 and 4 bands, with the R2 of 0.9685 and the total average relative error of 37.42%. Twenty PMS images obtained from 2017 to 2019 were applied to analyze Chla in Bohai sea. The results show that: (1) the new built Chla inversion model PMS-1 for the GF-4 PMS sensor can extract Chla distribution details in the Bohai Sea well. The high Chla content in the Bohai Sea is mainly located in coastal areas, such as the top of Laizhou Bay, Bohai Bay and Liaodong Bay, with the value being around 13 µg/L. The concentration of Chla in the Bohai Strait and northern Yellow Sea is relatively low with the value being around 5 µg/L. (2). Taking full advantage of the continuous observation of geostationary orbit satellite, GF-4 with a high-resolution sensor PMS of 50 m can effectively detect short-term change (changes within 10 min) in Chla concentration. The changes mainly appear at the southwest and northeast costal area as well as in the center of Bohai Sea with the change value of around 3 µg/L. (3) The change of Chla concentration in the Bohai sea is related to the environmental factors such as seawater temperature, salinity, illumination and nutrient salts, as well as the dynamic factors such as wind, flow field and tidal current.

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