Overview on Mangrove Forest Disaster Prevention and Mitigation Functions

This paper provides a comprehensive overview on coastal protection and hazard mitigation by mangroves.Previous stud-ies have made great strides to understand the mechanisms and influencing factors of mangroves’protection function,including wave energy dissipation,storm surge damping,tsunami mitigation,adjustment to sea level rise and wind speed reduction,which are sys-tematically summarized in this study.Moreover,the study analyzes the extensive physical models,based on indoor flume experi-ments and numerical models,that consider the interaction between mangroves and hydrodynamics,to help our understanding of mangrove-hydrodynamic interactions.Additionally,quantitative approaches for valuing coastal protection services provided by man-groves,including index-based and process-resolving approaches,are introduced in detail.Finally,we point out the limitations of previous studies,indicating that efforts are still required for obtaining more long-term field observations during extreme weather events,to create more real mangrove models for physical experiments,and to develop numerical models that consider the flexible properties of mangroves to better predict wave propagation in mangroves having complex morphology and structures.

Dynamics of ecosystems and anthropogenic drivers in the Yellow Sea Large Marine Ecosystem

In the developed world,governance of marine ecological environment is the important part of the national ecological and economic outcome.The Yellow Sea is one of large marine ecosystems in the seas of East Asia,which is an extension of one of the largest continental shelf areas,and forms a huge but shallow sediment body in its south area which is geographically unique in the world.As a region with the most fragile natural environment,unparalleled global ecological significance and the most urgent protection needs,the Yellow Sea ecological zone is becoming a common concern of countries around the Yellow Sea and beyond,such as tidal flats and the staging migratory birds(Murray et al.,2015).

Eutrophication of Jiangsu Coastal Water and Its Role in the Formation of Green Tide

Since 2007,the large-scale green tide caused by Ulva prolifera(U.prolifera)have occurred as a recurrent phenomenon in the southern Yellow Sea of China.Field surveys and satellite remote sensing showed that the small scattered patches of green tide algae were first observed along the Porphyra agriculture area of the Subei Shoal in late April.In this study,we attempted to identify the role of eutrophication in the origin of the green tide in the Subei Shoal and its adjacent area.Subei Shoal and its adjacent area are characterized by rich nutrients,especially NO_(3)^(-)-N,NH_(4)^(+)-N,PO_(4)^(3-)-P,and other bioavailable components(such as urea-N and amino acids).In the spring of 2017,the average concentrations of NO_(3)^(-)-N were 19.01±11.01μmolL^(-1),accounting for 86.68%of the dis-solved inorganic nitrogen(DIN).In addition,the average concentration of NH4^(+)-N was 2.51±1.60μmolL^(-1).PO_(4)^(3-)-P had an average concentration of 0.14±0.13μmolL-1.The average concentrations of urea-N and total hydrolyzed amino acids(THAA)were 1.73±1.36μmolL^(-1)and 1.33±0.80μmolL^(-1),respectively.Rich nutritive substances play a key role in the rapid production of U.prolifera and make the Jiangsu coastal water an incubator for green tide.

Asexual Reproduction of Aurelia coerulea Polyps in situ on Settling Plates in Jiaozhou Bay,China

Jellyfish blooms are increasingly prevalent coastal phenomena,with Aurelia coerulea being a significant contributor.The complex life history of jellyfish,featuring a sessile polyp stage,is a key factor in bloom formation,yet it is challenging to study in the field.This study aimed to describe the asexual reproduction of A.coerulea polyps in Jiaozhou Bay,China,and to assess their ability to form sedentary colonies and their relationship with environmental factors.Using settling plates,we observed polyps in situ and documented three asexual reproduction modes:budding,strobilation,and podocyst formation.Environmental parameters including temperature,salinity,dissolved oxygen(DO),chlorophyll a(Chl a),and the biomass of phytoplankton and zooplankton were monitored.Budding was the predominant reproductive method,featuring stolon budding in autumn and direct budding during the winter and spring seasons.Strobilation took place in the colder months,releasing ephyrae between April and May.Polyp abundance was positively correlated with seawater temperature and negatively correlated with DO concentration.Polyps at 1.0 m depth showed higher survivorship and proliferation over 8 months,whereas those at 2.0 m depth experienced a steady decline and died within 4 months.The study enhances our understanding of the life cycle and asexual reproduction strategies of A.coerulea polyps in the field,with implications for predicting and managing jellyfish blooms.The findings underscore the importance of temperature and DO in polyp survival and suggest that initial polyp population proliferation is crucial for long-term survival.

An estimation of nutrient fluxes to the East China Sea continental shelf from the Taiwan Strait and Kuroshio subsurface waters in summer

According to historical mean ocean current data through the field observations of the Taiwan Ocean Research Institute during 1991–2005 and survey data of nutrients on the continental shelf of the East China Sea（ECS） in the summer of 2006, nutrient fluxes from the Taiwan Strait and Kuroshio subsurface waters are estimated using a grid interpolation method, which both are the sources of the Taiwan Warm Current. The nutrient fluxes of the two water masses are also compared. The results show that phosphate（PO4-P）, silicate（SiO3-Si） and nitrate（NO3-N） fluxes to the ECS continental shelf from the Kuroshio upwelling water are slightly higher than those from the Taiwan Strait water in the summer of 2006. In contrast, owing to its lower velocity, the nutrient flux density（i.e., nutrient fluxes divided by the area of the specific section） of the Kuroshio subsurface water is lower than that of the Taiwan Strait water. In addition, the Taiwan Warm Current deep water, which is mainly constituted by the Kuroshio subsurface water, might directly reach the areas of high-frequency harmful alga blooms in the ECS.

Nutrient Structure of the Taiwan Warm Current and Estimation of Vertical Nutrient Fluxes in Upwelling Areas in the East China Sea in Summer

Based on field data for nutrients collected on the continental shelf of the East China Sea(ECS) during summer 2006, the structure and variations of nutrients in every water mass related to the Taiwan Warm Current(TWC) were analyzed. The supplementary effect of nutrient of upwelling on harmful algal blooms(HABs) in the ECS was also estimated, based on upwelling data. Then the maintenance contribution of nutrient of upwelling to HABs was assessed. The results showed that N/P ratio is fairly low in both surface and deep layers of the TWC, which possibly controls nutrient structure of the HABs-frequently-occuring areas. In upwelling areas, the rate of phosphate(PO4-P) uptake exceeds that of nitrate(NO3-N) of the TWC. The TWC may relieve PO4-P limitation during the process of HABs. Furthermore, upwelling plays an important role in providing nutrients to HABs. After estimating nutrient fluxes(NO3-N, PO4-P, Si O3-Si) in the upwelling areas along a typical section(S07), the results showed that the nutrient uptake rate is the greatest at 10-20 m below euphotic zone, sustaining the ongoing presence of HABs. The uptake rate of PO4-P is the highest among dissolved inorganic nutrients. Therefore, upwelling is most likely the main source of PO4-P supply to HABs.

A Time-dependent Stochastic Grassland Fire Ignition Probability Model for Hulun Buir Grassland of China

Grassland fire is one of the most important disturbance factors in the natural ecosystems.This paper focuses on the spatial distribution of long-term grassland fire patterns in the Hulun Buir Grassland located in the northeast of Inner Mongolia Autonomous Region in China.The density or ratio of ignition can reflect the relationship between grassland fire and different ignition factors.Based on the relationship between the density or ratio of ignition in different range of each ignition factor and grassland fire events,an ignition probability model was developed by using binary logistic regression function and its overall accuracy averaged up to 81.7%.Meanwhile it was found that daily relative humidity,daily temperature,elevation,vegetation type,distance to county-level road,distance to town are more important determinants of spatial distribution of fire ignitions.Using Monte Carlo method,we developed a time-dependent stochastic ignition probability model based on the distribution of inter-annual daily relative humidity and daily temperature.Through this model,it is possible to estimate the spatial patterns of ignition probability for grassland fire,which will be helpful to the quantitative evaluation of grassland fire risk and its management in the future.

Distribution, residence time, autotrophic production, and heterotrophic removal of DOP in the Mirs Bay, northern South China Sea

The importance of dissolved organic phosphorus(DOP) as a potential nutrient source for primary producers in marine systems has been recognized for up to eight decades, but currently, the understanding of the biogeochemistry of DOP is in its infancy. In the present study, monthly data between 2000 and 2014 were used to analyze the temporal and spatial distributions of DOP in the Mir Bay, the northern South China Sea. The DOP residence time(TDOP) was also investigated using a simple regression analysis in combination with chlorophyll a(Chl a) measurements while excess DOP(ΔDOP), produced by the biogeochemical processes of autotrophic production and heterotrophic removal, was determined using a two-component mixing mass-balance model in combination with salinity measurements. The results showed that the DOP concentration was(0.017±0.010) mg/L higher in the surface-water compared with the bottom-water and higher in the inner Tolo Harbour and waters adjacent to Shatoujiao compared with the main zone of the bay. Although seasonal changes and annual variability in the DOP were small, the surface DOP concentration was higher in the wet season(April–September)than in the dry season(October–March) due to the impacts of seaward discharges and atmospheric deposition into the bay. Measurement and regression results showed that the DOP release rate from phytoplankton production was about 1.83(gP)/(gChl a) and the TDOP was about 7 d, which implied that the DOP cycle in the bay was rapid. The ΔDOP was calculated from the model to be about 0.000 mg/L in the main zone of the bay and about 0.002 mg/L in the inner Tolo Harbour and waters adjacent to Shaotoujiao, suggesting that the autotrophic production of DOP was almost balanced by the heterotrophic removal in the main zone of the bay and dominated in the inner Tolo Harbour and waters adjacent to Shaotoujiao. In conclusion, the Mirs Bay is very productive and fairly heterotrophic.

Species-specific detection and quantification of scyphomedusae in Jiaozhou Bay,China,using a quantitative real-time PCR assay

Over the past decades,jellyfish occurred increasingly and abundantly in coastal areas worldwide.Usually,biomass of jellyfish,especially when they bloom,can be determined by visual counting.However,tiny individuals of jellyfish(e.g.,planulae,polyps,and ephyrae)are difficult to detect in the field.In this study,species-specific quantitative real-time PCR assays(qPCR)(SYBR Green I)targeting the mitochondrial 16S rDNA(mt-16S rDNA)of jellyfish were developed and were used to estimate the distribution and seasonal fluctuations of four jellyfish species(Nemopilema nomurai,Cyanea nozakii,Rhopilema esculentum,and Aurelia coerulea)in Jiaozhou Bay(JZB),China in 2013.The mt-16S rDNA of A.coerulea and N.nomurai was detected in most of the survey months and it peaked in July(1.03×10^(4) copies/L)and September(1.08×10^(6) copies/L),respectively.The mt-16S rDNA of C.nozakii occurred from August to October only with monthly mean values of 7.18-46.17 copies/L and was mainly located from the middle part to the outer part of the bay.The mt-16S rDNA of R.esculentum was the least abundant among the four species and was detected in only one sample(B2 station in March),with a value of 88.49 copies/L.The Spearman correlation test revealed that phytoplankton biomass was significantly and positively correlated with the mt-16S rDNA abundance of A.coerulea(R=0.37,P<0.01)and negatively with the mt-16S rDNA of N.nomurai(R=-0.36,P<0.01).The qPCR assay will enable the identification and quantification of jellyfish species in their whole life history and can be used as an approach in combination of the traditional jellyfish survey.

Glycogen content relative to expression of glycogen phosphorylase(GPH) and hexokinase(HK) during the reproductive cycle in the Fujian Oyster, Crassostrea angulata

Glycogen, a polymer of glucose, is an important means of storing energy. It is degraded by glycogen phosphorylase （GPH） and hexokinase （HK）, glycogen phosphorylase, and hexokinase cDNAs （Ca-GPH and Ca- HK, respectively）, which encode the primary enzymes involved in glycogen use, cloned and characterized and used to investigate the regulation of glycogen metabolism at the mRNA level in Crassostrea angulata. Their expression profiles were examined in different tissues and during different reproductive stages. Full-length cDNA of GPHwas 3 078 bp in length with a 2 607 bp open reading frame （ORF） predicted to encode a protein of 868 amino acids （aa）. The full-length HK cDNA was 3 088 bp long, with an ORF of 1 433 bp, predicted to encode a protein of 505 aa. Expression levels of both genes were found to be significantly higher in the gonads and adductor muscle than in the mantle, gill, and visceral mass. They were especially high in the adductor muscle, which suggested that these oysters can use glycogen to produce a readily available supply of glucose to support adductor muscle activity. The regulation of both genes was also found to be correlated with glycogen content via qRT-PCR and in situ hybridization and was dependent upon the stage of the reproductive cycle （initiation, maturation, ripeness）. In this way, it appears that the expression of Ca-GPH and Ca-HK is driven by the reproductive cycle of the oyster, reflecting the central role played by glycogen in energy use and gametogenic development in C. angulata. It is here suggested that Ca- GPH and Ca-HK can be used as useful molecular markers for identifying the stages of glycogen metabolism and reproduction in C. angulata.

The Burial of Biogenic Silica, Organic Carbon and Organic Nitrogen in the Sediments of the East China Sea

We sampled the sediments of the East China Sea during 2005 and 2006, and analysed the contents of the biogenic matters: biogenic silica, organic carbon, and organic nitrogen. From the surface distribution we found the contents of these substances to be in the ranges of 0.72%-1.64%, 0.043%-0.82%, and 0.006%-0.11%, respectively. Their distributions were similar to each other, being high inside the Hangzhou Bay and low outside the bay. The vertical variations of the contents were also similar. In order to discuss the relation between them we analysed the variations of content with depth. They increased in the first 7 cm and then decreased with depth. The peaks were found at depths between 20 to 25 cm. The distribution of carbonate showed an opposite trend to that of biogenic matters. The content of total carbon was relatively stable with respect to depth, and the ratio of high organic carbon to carbonate showed a low burial efficiency of carbonate, which means that the main burial of carbon is organic carbon. In order to discuss the source of organic matters, the ratio of organic carbon to organic nitrogen was calculated, which was 8.01 to 9.65, indicating that the organic matter in the sediments was derived mainly from phytoplankton in the seawater.

Removal of phenol by Isochrysis galbana in seawater under varying temperature and light intensity

Phenol is a common industrial chemical produced and transported worldwide largely.Therefore,accidental spillage of phenol in the ocean causes an increasing concern.Microalgae are promising to remove phenol from marine waters.However,temperature and light intensity are two main factors that markedly influence biodegradation in marine environments.In this study,a marine golden alga Isochrysis galbana is selected to research the removal of phenol under different temperatures(10-30℃)and light intensities(0-240μmol/(m^2·s)).The results show that the most suitable temperature and light intensity for phenol removal are 20℃and 180μmol/(m2·s),respectively,and 100 mg/L of phenol can be completely removed by microalga in 24 h at these conditions.I.galbana can also remove phenol under dark and low-temperature conditions.The removal of phenol by I.galbana at diverse temperatures and light intensities conform to first-order kinetics,and the process under dark conditions conform to zero-order kinetics.Thus,I.galbana can be used in the in-situ bioremediation of polluted seawater by phenol.

Seasonal Changes in Phytoplankton Biomass and Dominant Species in the Changjiang River Estuary and Adjacent Seas:General Trends Based on Field Survey Data 1959-2009

The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 ktg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level （including the nutrient supply from the terrestrial runoffs） was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that dia- toms were the main phytoplankton in this area, and Skeletonerna costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends： 1） Skeletonema （mainly S. costatum） was dominant throughout the year; and 2） seasonal succession trends were Coscinodiscus （spring） →Chaetoceros （summer and autumn） → Coscinodiscus （winter）. The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas： average annual phytoplankton biomass and dinoflagellate proportion both presented increased trends during the 1950s - 2000s.

Definition of water exchange zone between the Bohai Sea and Yellow Sea and the effect of winter gale on it

The marine dynamic environment of the Bohai Sea and the Yellow Sea in the winter of 2006 is simulated by the Regional Ocean Modelling System（ROMS） marine numerical model. Using the simulated temperature and salinity, the water exchange zone between the Bohai Sea and Yellow Sea is defined through the Spectral Mixture Model（SMM）. The influence of winter gales on the water exchange is also discussed. It is found that the Yellow Sea water masses in winter are distributed in a ＂tongue＂ shape in the Bohai Strait region, the water exchange zone presents a zonal distribution along the margin of the ＂tongue＂, with a tendency of running from northwest to southeast, and the water exchange is intensified at the tip of the ＂tongue＂. Besides, the coastal area in the northernmost Yellow Sea does not participate in the water exchange between the Bohai Sea and Yellow Sea. The result shows that the winter gale events play a role in enhancing the water exchange. It is specifically shown by the facts： the Yellow Sea warm current is enhanced to intrude the Bohai Sea by the gale process; the water exchange zone extends into the Bohai Sea; the water exchange belt in the southern part becomes wider; the mixture zone of river runoff with the Bohai Sea water upon its entry is enlarged and shifts northwards. Within two days after the gale process, the exchange zone retreats toward the Yellow Sea and the exchange zone resulted from the Huanghe River（Yellow River） runoff also shrinks back shoreward.

The Change Features of the West Boundary Bifurcation Line of the North Equatorial Current in the Pacific

The equatorial Current in the North Pacific(NEC) is an upper layer westward ocean current, which flows to the west boundary of the ocean, east of the Philippines, and bifurcates into the northerly Kuroshio and the main body of the southerly Mindanao current. Thus, NEC is both the south branch of the Subtropical Circulation and the north branch of the Tropical Circulation. The junction of the two branches extends to the west boundary to connect the bifurcation points forming the bifurcation line. The position of the North Pacific Equatorial Current bifurcation line of the surface determines the exchange between and the distribution of subtropical and tropical circulations, thus affecting the local or global climate. A new identification method to track the line and the bifurcation channel was used in this study, focusing on the climatological characteristics of the western boundary of the North Equatorial Current bifurcation line. The long-term average NEC west boundary bifurcation line shifts northwards with depth. In terms of seasonal variation, the average position of the western boundary of the bifurcation line is southernmost in June and northernmost in December, while in terms of interannual variation, from spring to winter in the years when ENSO is developing, the position of the west boundary bifurcation line of NEC is relatively to the north(south) in EI Ni?o(La Ni?a) years as compared to normal years.

Development of a Single-Column Model in RegCM4 and Its Preliminary Application for Evaluating PBL Schemes in Simulating the Dry Convection Boundary Layer

A single-column model(SCM)is developed in the regional climate model RegCM4.The evolution of a dry convection boundary layer(DCBL)is used to evaluate this SCM.Moreover,four planetary boundary layer(PBL)schemes,namely the Holtslag-Boville scheme(HB),Yonsei University scheme(YSU),and two University of Washington schemes(UW01,Grenier-Bretherton-Mc Caa scheme and UW09,Bretherton-Park scheme),are compared by using the SCM approach.A large-eddy simulation(LES)of the DCBL is performed as a benchmark to examine how well a PBL parameterization scheme reproduces the LES results,and several diagnostic outputs are compared to evaluate the schemes.The results show that the SCM is properly constructed.In general,with the DCBL case,the YSU scheme performs best for reproducing the LES results,which include well-mixed features and vertical sensible heat fluxes;the simulated wind speed,turbulent kinetic energy,entrainment flux,and height of the entrainment zone are all underestimated in the UW09;the UW01 has all those biases of the UW09 but larger,and the simulated potential temperature is not well mixed;the HB is the least skillful scheme,by which the PBL height,entrainment flux,height of the entrainment zone,and the vertical gradients within the mixed layer are all overestimated,and a inversion layer near the top of the surface layer is wrongly simulated.Although more cases and further testing are required,these simulations show encouraging results towards the use of this SCM framework for evaluating the simulated physical processes by the RegCM4.

Natural attenuation characteristics and comprehensive toxicity changes of C9 aromatics under simulated marine conditions

Microcosmic experiments were performed under a simulated marine environment to investigate the natural attenuation of C9 aromatics using nine components(propylbenzene,isopropylbenzene,2-ethyltoluene,3-ethyltoluene,4-ethyltoluene,1,2,3-trimethylbenzene,1,2,4-trimethylbenzene,1,3,5-trimethylbenzene,and indene).This research aims to assess the contribution of biodegradation and abiotic activity to total attenuation of C9 aromatics and ascertain the changes in the comprehensive toxicity of seawater in the natural environment.The process of natural attenuation indicates the agreement with pseudo-first-order kinetics for all nine components in microcosmic experiments.The half-lives of the nine main compounds in C9 aromatics ranged between 0.34 day and 0.44 day under optimal conditions.The experiments showed that the natural attenuation of nine aromatic hydrocarbonsmainly occurred via abiotic processes.Seawater samples significantly inhibited the luminescence of P.phosphoreum(the luminescence inhibition ratio reached 100%)at the beginning of the experiment.In addition,the toxicity declined slowly and continued for 25 days.The attenuation kinetics and changes in toxicity could be applied to explore the natural attenuation of C9 aromatics in the marine environment.

Modeling the Adverse Impact of Rainstorms on a Regional Transport Network

Cities are centers of socioeconomic activities,and transport networks carry cargoes and passengers from one city to another. However, transport networks are influenced by meteorological hazards, such as rainstorms,hurricanes, and fog. Adverse weather impacts can easily spread over a network. Existing models evaluating such impacts usually neglect the transdisciplinary nature of approaches for dealing with this problem. In this article, a mesoscopic mathematical model is proposed to quantitatively assess the adverse impact of rainstorms on a regional transport network in northern China by measuring the reduction in traffic volume. The model considers four factors: direct and secondary impacts of rainstorms, interdependency between network components, and recovery abilities of cities. We selected the Beijing-Tianjin-Hebei region as the case study area to verify our model.Socioeconomic, precipitation, and traffic volume data in this area were used for model calibration and validation.The case study highlights the potential of the proposed model for rapid disaster loss assessment and risk reduction planning.