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The South China Sea (SCS), situated in southern China, at the junction of the Pacific Plate, the Eurasian Plate, and the Indian Ocean Plate, is a northeast-southwest trending semi-enclosed sea. It spans an area of approximately 3.5 million square kilometers and has an average water depth of about 1 200 m, its deepest point reaching 5 559 m. In 2021, a scientific expedition (called as U1 voyage) in the South China Sea was organized by the Innovation Research Team of Guangdong Special Key Program from March to April, this marks the first comprehensive scientific research voyage to the southern U-boundary corridor. Consisting of a total of 30 papers, this special issue is to share a portion of the research findings from this scientific expedition U1 voyage, covering six aspects: 1) characteristics of the marine ecosystem in the SCS and its response to marine dynamic processes; 2) multi-scale marine dynamic processes, sea-air interactions, and forecasting techniques in the SCS; 3) geomorphology and geological structure; 4) sedimentary processes and resource potential in the SCS; 5) geostrategy, rights and interests maintenance and strategic countermeasures in the SCS; 6) marine scientific instruments. By integrating the scientific research with the study of history, jurisprudence and international strategies, this issue presents new insights into the formation history and scope evolution of the SCS, and it also seeks to establish a new scientific framework based on the marine governance and development of the SCS. [ABSTRACT FROM AUTHOR]

The log-ratio method (LRM) proposed by Stumpf et al. has been widely used to map bathymetry from multispectral imagery for oligotrophic waters, while the selection criteria of bands for the LRM have been subject to tradeoffs between maximum detectable depth and sensitivity. In this article, we first applied a method for global sensitivity analysis to a semianalytical forward model of optically shallow waters with the WorldView-2 band-set. The results show that the sensitive wavelength band in water-leaving reflectance for water depth varies from the longer wavelength band to the shorter wavelength band with increasing water depth. Then, we developed an adaptive blended algorithm approach (ABAA) to seamlessly map bathymetry from the shallower region to the deeper region. The LRM with different band combinations was selected for the sub-algorithms of the ABAA. The subalgorithms and depth range used for each subalgorithm of the ABAA were automatically determined by the proposed applicable depth range analysis that considers logarithmic regression for the LRM. The ABAA was applied to WorldView-2 and Landsat-8 imagery of the Xisha Qundao. When the in situ bathymetry data are available, compared with the LRM with the blue and green bands, the ABAA significantly improves the accuracy of the estimated depth, especially for waters shallower than 6 m (root–mean- square error (RMSE) = 0.31 to 0.94 m for WorldView-2 data, RMSE= 0.25 to 1.42 m for Landsat-8 data). When the in situ bathymetry data are absent, the ABAA performs better than the LRM with a single band ratio and an optimization-based method overall. [ABSTRACT FROM AUTHOR]

In the South China Sea (SCS), Sthenoteuthis oualaniensis (S. oualaniensis) generally has the highest stock density in spring and occupies an important position in fisheries. The responses of S. oualaniensis to marine environments in the north-central SCS in spring (March to May) from 2006 to 2010 were analyzed using satellite and in situ observations, with generalized additive models (GAMs). A high proportion variation in catch per unit effort (CPUE) was explained by environmental variables, including sea surface temperature (SST; explaining 13.8%) and the interaction between SST and chlorophyll a (Chl-a) concentration (explaining 16.9%). SSTs within the range of 24–28°C and Chl-a concentrations within 0.10–0.35 mg/m3 had positive effects on S. oualaniensis CPUE, and SST within 28–29.5°Cand Chl-a concentrations within 0.05–0.20 mg/m3 had negative effects. In addition, the response time of the maximum standardized catch per unit effort (SCPUE) in May to the maximum Chl-a in March was approximately six ten-day time step. The higher Chl-a and smaller stock size of S. oualaniensis in early March 2008 were partly associated with climatic anomalies caused by La Niña in spring and the limitation of S. oualaniensisby low temperature in 2008. The findings in this study can help better protect and manage S. oualaniensis resources in the SCS. [ABSTRACT FROM AUTHOR]

This study investigates the processes of occasional sea surface temperature (SST) fronts and their impacts on chlorophyll-a concentration (chl-a) in the South China Sea (SCS), based on satellite remote sensing and in situ observations in 2009-2013. The SST fronts were detected by an entropy-based edge detection algorithm method from satellite-derived SST images with a 0.011° grid size. Three offshore SST front case studies (S1, S2 and S3) at the peripheries of eddies in the northern SCS were studied. In case S1 in September 2013, two SST fronts were detected with gradient magnitudes (GMs) greater than 0.06°C km-1 in the cyclonic eddy and 0.08°C km-1 in the periphery waters, and the fronts only existed for one and two days, respectively. After three and seven days, the high chl-a was found in the strong SST front waters which were about 51 and 54% higher than the concentration in the surrounding waters. The depth of the maximum chl-a elevated from the subsurface (50 m) to the surface. In case S2 in August 2013, two SST fronts were detected at the periphery of an anti-cyclonic eddy with GM stronger than 0.06°C km-1 and only existed for one day. After two days, the chl-a in the SST front waters was about 40% higher than the levels in the surrounding waters. In case S3 in June 2009, the GM of the eddy-feature SST front was stronger than 0.12°C km-1 and existed for three days, which was generated by tropical cyclone Linfa. The chl-a in the eddy-feature phytoplankton bloom was 6 times higher than in the surrounding waters. The results show that, in general, occasional offshore SST fronts at peripheries of eddies have stronger influence on surface chl-a, comparing to those seasonal coastal and permanent offshore SST fronts, via ‘Wind Pump’ effects. [ABSTRACT FROM AUTHOR]

In optically complex waters, it is important to evaluate the accuracy of the standard satellite chlorophyll-a (chl-a) concentration algorithms, and to develop accurate algorithms for monitoring the dynamics of chl-a concentration. In this study, the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remotesensing reflectance and concurrent in situ measured chl-a (2010– 2013) were used to evaluate the standard OC3M algorithm (ocean chlorophyll-a three-band algorithm for MODIS) and Graver–Siegel– Maritorena model version 1 (GSM01) algorithm for estimating chla concentration in the Bohai and Yellow Seas (BYS). The results showed that the chl-a algorithms of OC3M and GSM01 with global default parameters presented poor performance in the BYS (the mean absolute percentage difference (MAPD) and coefficient of determination (R²) of OC3M are 222.27% and 0.25, respectively; the MAPD and R² of GSM01 are 118.08% and 0.07, respectively). A novel statistical algorithm based on the generalized additive model (GAM) was developed, with the aim of improving the satellite-derived chl-a accuracy. The GAM algorithm was established using the in situ measured chl-a concentration as the output variable, and the MODIS above water remote-sensing reflectance (visible bands at 412, 443, 469, 488, 531, 547, 555, 645, 667, and 678 nm) and bathymetry (water depth) as input variables. The MAPD and R² calculated between the GAM and the in situ chl-a concentration are 39.96% and 0.67, respectively. The results suggest that the GAM algorithm can yield a superior performance in deriving chl-a concentrations relative to the standard OC3M and GSM01 algorithms in the BYS. [ABSTRACT FROM AUTHOR]

In this study, a total of 37 images of Landsat Operational Land Imager/Thematic Mapper/Enhanced Thematic Mapper plus were adopted to delineate the qualitative changes of Suspended Sediment Concentration (SSC) in Hangzhou Bay, China. Combined with in-situ SSC, remote sensing reflectance of the water (Rrs), water depth and simulated currents, the influence of both seabed topography and tidal currents on the SSC distribution was analysed. The results showed: (1) four High SSC Areas (HSA) and two Low SSC areas (LSA) in Hangzhou Bay. (2) SSC has a negative correlation with bathymetry, which is especially obvious during mid to late period of flood tide. HSAs appear in the shallow water (3–7 m depth) area, while the LSAs distribute in the deep water area (10–15 m depth). (3) The surface SSC distribution during the mid to late period of flood tide can help us estimate the topography information. The results of this paper can be used to other coastal embayments similar to Hangzhou Bay. [ABSTRACT FROM AUTHOR]

This study investigates the spatial variation of suspended sediment concentration (SSC) induced by Hangzhou Bay Bridge (HBB) in the coastal waters of the East China Sea. Based on Landsat Thematic Mapper (TM), Operational Land Imager (OLI) data and in-situ measurements, spectral characteristics of waters in Hangzhou Bay and SSC retrieved from near infrared single band have been analyzed. The results revealed significant difference of SSC in the water on two sides of HBB. SSC increases downstream of the bridge under conditions of low turbidity (SSC < 300 mg l −1 ) upstream water, while SSC decreases when high turbidity water (SSC > 400 mg l −1 ) upstream. This study shows that the interaction of bridge piers and currents has important influences on SSC distribution by inducing hydrodynamic factors and by changing suspended sediment transport. Remotely sensed data with high spatial resolution as TM and OLI can be applied to investigate SSC variations induced by a bridge in the bay area. [ABSTRACT FROM AUTHOR]

The spatial distribution of suspended sediment concentration (SSC) in spring (February–April) from 2007 to 2013 in the Yangtze (Changjiang) estuary and coastal seas was analysed using remote-sensing data. The results indicated that areas of high SSC drifted northwards along the coast about 100 km away from the Yangtze estuary. SSC increased considerably in both mass and area in 2013. The first principal component analysis (PCA) pattern explained the dominant spatial distribution pattern of SSC in the study area. This highly clustered controlling pattern may have been caused by the joint effects of Yangtze diluted water (YDW), the Taiwan Warm Current (TWC), coastal currents, northeasterly winds, and the shallow coastal shelf. The SSC dispersed and extended into a wide area, and the main range of sediment concentration was located in an area the shape of a trapezium (31.9° N–33.8° N, 122° E–125.5° E, 30.7° N–32.6° N). YDW and the TWC could be the main reason for this northward drift of SSC. The long-term sinking of suspended sediment in clustered areas may have contributed considerably to the formation of the shallow coastal shelf above the 60 m isobath. [ABSTRACT FROM AUTHOR]

Abstract: It is well known that tropical cyclones can cause upwelling, decrease of sea surface temperature, increase of chlorophyll-a (Chl-a) concentration and enhancement of primary production. But little is known about the response of dissolved oxygen (DO) concentration to a typhoon in the open ocean. This paper investigates the impact of a typhoon on DO concentration and related ecological parameters using in situ and remote sensing data. The in situ data were collected 1week after the passage of the super-typhoon Nanmadol in the northern South China Sea in 2011. An increase in DO concentration, accompanied by a decrease in water temperature and an increase in salinity and Chl-a concentration, was measured at sampling stations close to the typhoon track. At these stations, maximum DO concentration was found at a depth of around 5m and maximum Chl-a concentration at depths between 50 and 75m. The layer of high DO concentration extends from the surface to a depth of 35m and the concentrations stay almost constant down to this depth. Due to the passage of the typhoon, also a large sea level anomaly (21.6cm) and a high value of Ekman pumping velocity (4.0×10−4 ms−1) are observed, indicating upwelling phenomenon. At the same time, also intrusion of Kuroshio waters in the form of a loop current into the South China Sea (SCS) was observed. We attribute the increase of DO concentration after the passage of the typhoon to three effects: (1) entrainment of oxygen from the air into the upper water layer and strong vertical mixing of the water body due to the typhoon winds, (2) upwelling of cold nutrient-rich water which stimulates photosynthesis of phytoplankton and thus the generation of oxygen, which also increases the DO concentration due to cold water since the solubility of oxygen increase with decreasing water temperature, and, possibly, (3) transport of DO enriched waters from the Western Pacific to the SCS via the intrusion of Kuroshio waters. [Copyright &y& Elsevier]

Multi-source remote-sensing data were used to study the aftermath of the 2006 Lebanon oil spill: Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m data and advanced synthetic aperture radar (SAR) images were used to delineate the extent of the oil spill; QuikScat data were used to derive the wind field; and MODIS Ocean Colour data were used to demonstrate the variability of chlorophyll-a concentration (Chl-a) and sea surface temperature (SST). No significant changes were found in marine phytoplankton in the first few months after the oil spill. However, a big phytoplankton bloom was observed after 10 months, when Chl-a increased from 0.1 to 1.0 mg m–3. After considering the time-series variability of Chl-a and SST and the spatial variability of Chl-a and bathymetry, we concluded that this phytoplankton bloom was probably related to the Lebanon oil spill. [ABSTRACT FROM AUTHOR]

Ocean acidification, a consequence of the ocean absorbing about a third of the anthropogenic carbon dioxide (CO2) emitted into the atmosphere, is poised to affect biogeochemical cycles and the seawater chemical system. Traditional research methods, such as field and in situ sampling, are precise and reliable, but are inherently limited in spatial and temporal coverage and resolution. This article summarizes remotely sensed products, including air-sea CO2 fluxes, total alkalinity, suspended calcite (particulate inorganic carbon), particulate organic carbon and calcification rates, which can be used to observe ocean acidification indirectly. Confounding factors and limitations of algorithms are major sources of errors. This article also discusses remote-sensing algorithms and satellite technology developments. Remote sensing, considering its great advantages and successful applications in climate change, will be an important tool in future studies of ocean acidification. [ABSTRACT FROM AUTHOR]

Phytoplankton blooms often occur in the offshore region northwest of Luzon Islands in winter. Using remote sensing data, including sea-surface temperature, monthly-mean mixed layer depth (MLD), wind speed (SP), and SeaWiFS-derived chlorophyll-a (Chl-a) data from September 1997 to February 2007, we investigate the spatial and interannual variation of the winter phytoplankton in the region along with in situ GTS (the Global Telecommunications System) XBT (Expendable Bathythermograph) data and climatological nitrate and temperature observations from World Ocean Atlas 2005. The results clearly show high winter phytoplankton biomass (i.e. Chl-a) and its interannual variation in the region. The lower Chl-a concentrations (∼0.2 mg m−3) appeared often in winters (e.g. 1997 and 1998) when there was weaker wind speed, Ekman pumping velocity (EPV) and entrainment velocity (EV), and shallower MLD; conversely higher Chl-a (>0.5 mg m−3) appeared in winters (e.g. 2001 and 2003) when there was higher subsurface temperature, stronger wind speed, EPV and EV, and deeper MLD. It is thought that wind-induced upwelling (Ekman pumping) and entrainment mixing may be important factors leading to the high winter Chl-a, and the wind speed and wind stress curl were good indicators of higher Chl-a; the positive correlation between subsurface temperature (and MLD) and Chl-a represented more warm water intrusion from the Northwest Pacific Ocean into the region in the higher Chl-a years. [ABSTRACT FROM AUTHOR]

Abstract: Phytoplankton blooms appear in winter (Nov–Jan) in the southwest of Luzon Strait, South China Sea, which is an oligotrophic region in general. To understand dynamic features of the winter phytoplankton bloom southwest of Luzon Strait, this study analyzes seven years (2000–2006) of remote sensing data of Chlorophyll a, sea surface temperature, and ocean vector winds, along with in situ observations of dissolved oxygen, nutrients (nitrate, phosphate, and silicate), and physical oceanographic parameters mixed layer depth, Ekman pumping velocity, and entrainment velocity. The results demonstrate that the winter phytoplankton bloom in the southwest of Luzon Strait is primarily induced by both Ekman pumping-driven upwelling (observed at about 50m under sea surface) and upper mixed layer entrainment. The area of winter phytoplankton blooms is about 2.58×104 km2, based on Empirical Orthogonal Function analysis. The seasonal variability of the bloom is associated with monsoonal wind forcing. [ABSTRACT FROM AUTHOR]

The diurnal sea surface temperature (D-SST, which is the daytime SST minus the night-time SST) and its relationship with heavy phytoplankton blooms were observed using satellite and in situ data. Two phytoplankton bloom events covering large areas in the East China Sea (ECS) were analysed to investigate the reactions among D-SST, chlorophyll-a (chl-a) concentration, suspended sediment (SS), coloured dissolved organic matter (CDOM), wind speed (WS) and solar radiation (SR). The results showed a positive relationship between D-SST and chl-a concentration in phytoplankton bloom areas. Further analyses of 12 major phytoplankton bloom events (total area >1000 km2) occurring between 2000 and 2005 in the ECS, accompanied by in situ observation data in Daya Bay, confirmed a positive correlation between chl-a concentration and D-SST. These results showed that an increase in D-SST may be found in heavy phytoplankton bloom areas. The present study represents an important step for understanding the influence of phytoplankton on ocean conditions. [ABSTRACT FROM AUTHOR]

Analysis of satellite remote sensing data has revealed changes in distribution of chlorophyll-a (Chl-a) and sea surface temperature (SST) in the Indian Ocean during the South Asian tsunami in December 2004. Chl-a data derived from Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) images were examined for the period from 1998 to 2005. Around the epicentre of the Sumatra earthquake, the Chl-a concentration was found to increase prior to the main event on 26 December 2004 and then decrease during the tsunami event, while a high SST (∼30-31°C) was observed in and around the epicentral region. Chl-a concentrations in the coastal waters of the Southeast Asian countries were remarkably low during and after the tsunami. Similar but relatively small variations in Chl-a and SST were observed during the second earthquake on 28 March 2005. Analysis of Chl-a, SST, wind and upwelling water has provided information for understanding the changes in Chl-a concentration during the tsunami. A very large offshore phytoplankton bloom (∼300 km2) appeared to the southeast of Sri Lanka about 3 weeks after the tsunami; this might have been caused by a tropical storm that could be responsible for the enhancement of nutrients. [ABSTRACT FROM AUTHOR]

Abstract: The Sumatra tsunami on 26 December, 2004 in the Indian Ocean was generated by one of the largest earthquakes of the past 100 years. The present study investigated spatial and temporal changes of suspended sediment concentration (SSC) in North-East Indian Ocean (NEIO) after the Sumatra tsunami used satellite remote sensing data. The nLw551 products of MODIS-aqua data (using as indexing SSC) were analyzed for 5 years (2002–2006). Result shows SSC notably increased (55.6–200%) in large river estuaries along coast of the Bay of Bengal (BOB) in a short time (4 weeks) after the tsunami, especially the northwest coast of Indonesia, southeast coast of Myanmar, as well as the north offshore of BOB. Those increases were mainly caused by the re-suspension function induced by the initial surge of the tsunami. Monthly analysis indicates increases (4.26%) of SSC of the entire North-East Indian Ocean area in 2005; especially in November 2005 when increase of SSC increased by about 6.19% compared with other years; those may mainly be caused by the destruction of coastal vegetation and modifying of estuaries or wetlands by the 2004 tsunami. The increases of SSC have different mechanism in different region and period after the tsunami. [Copyright &y& Elsevier]

Abstract: Monitoring of spatial and temporal distribution of chlorophyll (Chl-a) concentrations in the aquatic milieu is always challenging and often interesting. However, the recent advancements in satellite digital data play a significant role in providing outstanding results for the marine environmental investigations. The present paper is aimed to review ‘remote sensing research in Chinese seas’ within the period of 24 years from 1978 to 2002. Owing to generalized distributional pattern, the Chl-a concentrations are recognized high towards northern Chinese seas than the southern. Moreover, the coastal waters, estuaries, and upwelling zones always exhibit relatively high Chl-a concentrations compared with offshore waters. On the basis of marine Chl-a estimates obtained from satellite and other field measured environmental parameters, we have further discussed on the applications of satellite remote sensing in the fields of harmful algal blooms (HABs), primary production and physical oceanographic currents of the regional seas. Concerned with studies of HABs, satellite remote sensing proved more advantageous than any other conventional methods for large-scale applications. Probably, it may be the only source of authentic information responsible for the evaluation of new research methodologies to detect HABs. At present, studies using remote sensing methods are mostly confined to observe algal bloom occurrences, hence, it is essential to coordinate the mechanism of marine ecological and oceanographic dynamic processes of HABs using satellite remote sensing data with in situ measurements of marine environmental parameters. The satellite remote sensing on marine environment and HABs is believed to have a great improvement with popular application of technology. [Copyright &y& Elsevier]

The 1800 MW Daya Bay Nuclear Power Station (DNPS), China''s first nuclear power station, is located on the coast of the South China Sea. DNPS discharges 29 10×105 m3 year−1 of warm water from its cooling system into Daya Bay, which could have ecological consequences. This study examines satellite sea surface temperature data and shipboard water column measurements from Daya Bay. Field observations of water temperature, salinity, and chlorophyll a data were conducted four times per year at 12 sampling stations in Daya Bay during January 1997 to January 1999. Sea surface temperatures were derived from the Advanced Very High Resolution Radiometer (AVHRR) onboard National Oceanic and Atmospheric Administration (NOAA) polar orbiting satellites during November 1997 to February 1999. A total of 2905 images with 1.1×1.1 km resolution were examined; among those images, 342 have sufficient quality for quantitative analysis. The results show a seasonal pattern of thermal plumes in Daya Bay. During the winter months (December to March), the thermal plume is localized to an area within a few km of the power plant, and the temperature difference between the plume and non-plume areas is about 1.5 °C. During the summer and fall months (May to November), there is a larger thermal plume extending 8–10 km south along the coast from DNPS, and the temperature change is about 1.0 °C. Monthly variation of SST in the thermal plume is analyzed. AVHRR SST is higher in daytime than in nighttime in the bay during the whole year. The strong seasonal difference in the thermal plume is related to vertical mixing of the water column in winter and to stratification in summer. Further investigations are needed to determine any other ecological effects of the Daya Bay thermal plume. [Copyright &y& Elsevier]

This paper uses the Argo sea surface salinity (SSSArgo) before and after the passage of 25 tropical cyclones (TCs) in the Bay of Bengal from 2015 to 2019 to evaluate the sea surface salinity (SSS) of the Soil Moisture Active Passive (SMAP) remote sensing satellite (SSSSMAP). First, SSSArgo data were used to evaluate the accuracy of the 8-day SMAP SSS data, and the correlations and biases between SSSSMAP and SSSArgo were calculated. The results show good correlations between SSSSMAP and SSSArgo before and after TCs (before: SSSSMAP = 1.09SSSArgo−3.08 (R2 = 0.69); after: SSSSMAP = 1.11SSSArgo−3.61 (R2 = 0.65)). A stronger negative bias (−0.23) and larger root-mean-square error (RMSE, 0.95) between the SSSSMAP and SSSArgo were observed before the passage of 25 TCs, which were compared to the bias (−0.13) and RMSE (0.75) after the passage of 25 TCs. Then, two specific TCs were selected from 25 TCs to analyze the impact of TCs on the SSS. The results show the significant SSS increase up to the maximum 5.92 psu after TC Kyant (2016), which was mainly owing to vertical mixing and strong Ekman pumping caused by TC and high-salinity waters in the deep layer that were transported to the sea surface. The SSSSMAP agreed well with SSSArgo in both coastal and offshore waters before and after TC Roanu (2016) and TC Kyant (2016) in the Bay of Bengal. [ABSTRACT FROM AUTHOR]

Mangrove deforestation is occurring globally at a rapid rate, and is causing serious ecological and economic losses on all scales. Monitoring mangrove changes is the first important step for mangrove management and conservation. Zonation of mangrove species (ZMS) is the predictable and discrete ordering of mangrove species caused by a unique, intertidal environment. Mapping the ZMS is critical to understanding the mangrove community at a species level. In this paper, the Standard Deviational Ellipse (SDE) was proposed as a method to evaluate mangrove species from a new dimension of directional changes. Three dominant mangrove species, Kandelia obovata (KO), Avicennia marina (AM), and Acanthus ilicifolius (AI), in Mai Po, Hong Kong were analyzed using SDEs based on the time series Système Pour l’Observation de la Terre (SPOT) and Gaofen-1 (GF-1) satellite images. The SDE results demonstrated that in the past 25 years: (1) The overall spatial extent of the mangroves in Mai Po expanded significantly, approximately from 150 to 350 Ha, and show a zonation pattern with a clear sequence of species perpendicular to the shoreline; (2) KO was the dominant species in most years, showing the strongest directional characteristic; (3) All three species zones have moved toward the north and west, as observed by the SDE centers. The SDE was proved to be a useful tool for understanding the temporal and spatial changes of mangrove zonation. [ABSTRACT FROM AUTHOR]

Fishery resources along China’s coasts have been declining. Could those decline be alleviated by deploying artificial reefs (ARs) in suitable areas? This study investigates effects of a big project conducted in December 2007 that deployed ARs in the southwestern part of Daya Bay. The ARs cover a total dimension of 966.10 × 2850.60 m 2 and surface area of 91,500 m 2 . This study analyzed the spatial and temporal variations of ecological factors, including Chlorophyll a concentrations (Chl-a), nutrients, attaching organisms and nekton resources, on and around the ARs using both satellite (Moderate Resolution Imaging Spectroradiometer, MODIS) and in situ data. Results showed that the potential affected area of ARs in Daya Bay reached a distance of 4.9 km in the water depth of 12.0–15.2 m. In the study area, Chl-a level reached 2.93 mg m −2 during the post-AR period (2008–2012), that was higher than the pre-AR period (2002–2007) (2.37 mg m −2 ). Nekton biomass increased by 4.66–16.22 times compared with that in the pre-AR survey, and the species diversity increased by 15%–23%. This parallel trend suggested that ARs might have contribution to the increase in nekton biomass. Long-term observations shall be conducted to understand the response of phytoplankton to ARs. [ABSTRACT FROM AUTHOR]

We investigated the impact of the Ningbo North Dyke (NND) built in 2012–2014 in the coastal waterway of East China Sea on local suspended sediment concentration (SSC). Several multi-spectral satellite images acquired by the Landsat Thematic Mapper (TM)/Operational Land Imager (OLI) in 2008–2017 were used. We analyzed the change of SSC and spectral curves of study area around small NND (the NND's total length less than 1 km) using a prior model proposed in our previous study. We found that SSC near NND in the Meishan Waterway decreased after the NND construction by 200–300 mg/l, so that clean blue water is now observed in the Meishan Waterway, apparently thanks to stable dynamic environment in presence of NND. Our results reveal the impact of a small coastal dyke with length less than 1 km on the movement and distribution of SSC from a remote-sensing perspective. [ABSTRACT FROM AUTHOR]