Mangrove forests are under the stress of sea level rise(SLR)which would affect mangrove soil biogeochemistry.Mangrove soils are important sources of soil-atmosphere greenhouse gas(GHG)emissions,including carbon dioxid...Mangrove forests are under the stress of sea level rise(SLR)which would affect mangrove soil biogeochemistry.Mangrove soils are important sources of soil-atmosphere greenhouse gas(GHG)emissions,including carbon dioxide(CO_(2)),methane(CH_(4))and nitrous oxide(N_(2)O).Understanding how SLR influences GHG emissions is critical for evaluating mangrove blue carbon capability.In this study,potential effects of SLR on the GHG emissions were quantified through static closed chamber technique among three sites under different intertidal elevations,representing tidal flooding situation of SLR values of 0 cm,40 cm and 80 cm,respectively.Compared with Site SLR 0 cm,annual CO_(2) and N_(2)O fluxes decreased by approximately 75.0%and 27.3%due to higher soil water content,lower salinity and soil nutrient environments at Site SLR 80 cm.However,CH_(4) fluxes increased by approximately 13.7%at Site SLR 40 cm and 8.8%at Site SLR 80 cm because of lower salinity,higher soil water content and soil pH.CO_(2)-equivalent fluxes were 396.61 g/(m^(2)·a),1423.29 g/(m^(2)·a)and 1420.21 g/(m^(2)·a)at Sites SLR 80 cm,SLR 40 cm and SLR 0 cm,respectively.From Site SLR 0 cm to Site SLR 80 cm,contribution rate of N_(2)O and CH_(4) increased by approximately 7.42%and 3.02%,while contribution rate of CO_(2) decreased by approximately 10.44%.The results indicated that warming potential of trace CH_(4) and N_(2)O was non-negligible with SLR.Potential effects of SLR on the mangrove blue carbon capability should warrant attention due to changes of all three greenhouse gas fluxes with SLR.展开更多
In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic a...In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic aromatic hydrocarbon(PAHs),organic carbon and nitrogen were seasonally investigated at site A(with horseshoe crab presence),sites B and C(without horseshoe crab presence)in the Crocodile Island intertidal zone in Xiamen from June 2018 to July 2019.The results showed that most of the community parameters of benthic macrofauna,population parameters of common benthic macrofauna and environmental parameters were significantly different at the sites with horseshoe crab versus non-horseshoe crab sites.A two-way ANOVA test showed that the densities of Ceratonereis erythraeensis and Sigambra hanaokai had significant site variation.Cluster and nonmetric multi-dimensional scaling(NMDS)analysis showed the community composition of benthic macrofauna was significantly different among the three sampling sites over four seasons.The mean sand content at site A(64.32%)was higher than those at site B(36.01%)and site C(18.86%).Conversely,the mean contents of silt,clay,Cr,Co,Ni,organic carbon,organic nitrogen,phenanthrene,and pyrene at site A were lower than those at site B and site C.These observations are consistent with the expected preferences of horseshoe crabs to live in areas with 60%sand content,which is associated with abundant and edible clamworms in the Crocodile Island intertidal zone,Xiamen.展开更多
In order to determine the phytoplankton community composition, the modification and optimizing of the CHEMical TAXonomy(CHEMTAX) running was carried out through samples grouping, successive run and evaluate the result...In order to determine the phytoplankton community composition, the modification and optimizing of the CHEMical TAXonomy(CHEMTAX) running was carried out through samples grouping, successive run and evaluate the results for HPLC-pigment samples in the South China Sea(SCS). The vertical distribution of the ratio of pigment to total Chl a(TChl a) exhibited three different patterns, including increasing with depth pattern(e.g., But-Fuco), decreasing with depth pattern(e.g., Zea) and increasing at deep chlorophyll maximum(DCM) pattern(e.g., Hex-Fuco). The vertical profiles for Fuco/TChl a and Pras/TChl a was higher in coast than in the shelf and basin, and the Zea and Dv-Chl a expressed conversely. So the samples in the coastal stations must be separated for the cluster analysis group procedure in the SCS. Successive run was introduced into the CHEMTAX calculation and the output results were evaluated by the convergence of pigment/TChl a ratios. Most of the ratios were well converged at the fifth running, except Zea/TChl a for Prochlorococcus and Chl b/TChl a for prasinophytes and so on. To evaluate the fifth running's results, haptophytes_8 and chlorophytes were two phytoplankton groups with much uncertainty. But the fifth estimated value was better than running once was supported by the regression evidence between the measured pigment concentration and calculation values. Synechococcus was another component with much mutability, and the CHEMTAX's result should be compared to the flow cytometry's cell abundance.展开更多
As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to det...As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to determine the resistance of K. obovata seedlings to low temperature stress by cold acclimation and to explain the mechanisms for alleviating cold injury. To understand these mechanisms, seedlings that were acclimatized and not acclimatized were exposed to 5℃/- 2℃(day/night)for 48 h.Results showed that low temperature stress reduced leaf photosynthesis of non-acclimatized seedlings by inducing oxidative stress and structural damage to chloroplasts. These phenomena were shown by increasing levels of malondialdehyde (MDA), O2-and H2O2, as well as decreasing enzyme activities in the ascorbate–glutathione (AsA-GSH) cycle. However, cold-acclimatized seedlings had improved photosynthetic rates and efficiency of photosystem II (PSII) under low temperature stress. Compared with non-acclimatized seedlings, leaves of coldacclimatized seedlings under low temperature stress for 48 h exhibited higher anti-oxidative enzyme activities, lower levels of O2^- and H2O2, less damage to chloroplast structure, and removed 33.7% of MDA at low temperature stress for 48 h. The data indicate that cold acclimation enhances photosynthetic capacity by effectively regulating activation in the PSII electron transport and the AsA–GSH cycle to scavenge excess ROS in chloroplasts, while the latter is more important.展开更多
The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the wester...The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the western and southwestern Taiwan Strait during the spring cruise of 2019,we analyze the spatial distributions of temperature(T)and salinity(S)in the investigation area.Then by using the fuzzy cluster method combined with the T-S similarity number,we classify the investigation area into 5 water masses:the Minzhe Coastal Water(MZCW),the Taiwan Strait Mixed Water(TSMW),the South China Sea Surface Water(SCSSW),the South China Sea Subsurface Water(SCSUW)and the Kuroshio Branch Water(KBW).The MZCW appears in the near surface layer along the western coast of Taiwan Strait,showing low-salinity(<32.0)tongues near the Minjiang River Estuary and the Xiamen Bay mouth.The TSMW covers most upper layer of the investigation area.The SCSSW is mainly distributed in the upper layer of the southwestern Taiwan Strait,beneath which is the SCSUW.The KBW is a high temperature(core value of 26.36℃)and high salinity(core value of 34.62)water mass located southeast of the Taiwan Bank and partially in the central Taiwan Strait.展开更多
Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixa...Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.展开更多
Based on the latest submarine topography data of the China 908 Project(China offshore marine environmental comprehensive investigation and assessment),we analyzed the general China offshore submarine topographical cha...Based on the latest submarine topography data of the China 908 Project(China offshore marine environmental comprehensive investigation and assessment),we analyzed the general China offshore submarine topographical characteristics and the factors influencing its development.The submarine topography off the coast of China follows the NW-SE trend of the land topography.The gradient of the submarine topography ranges from 0.2%to 1.6%with an average gradient of about0.8%.The depth contours run mostly parallel to the coast,and extend out to sea in estuary areas.The submarine topography is dominated by the geological structure,which shows the typical characteristics of two uplifts and two subsidence events from north to south.The geological structure combined with the different sedimentary environments and complex hydrodynamic conditions produced topography that can be characterized by three types:sedimentary basins,compressionuplift,and transition form.In the sedimentary basin and compression-uplift regions,the topographical undulation is small,sediments are fine-grained,and the currents flow in a single direction,leading to bays with sedimentary plains and underwater accumulation slopes,which are of the same tectonic origin.Transition-type topography is characterized by strong undulations and mixed-size sediment particles,terraces and scarps inshore and shelf plains and erosion-deposition landforms offshore.This is a result of incomplete fault block development and repeated transgressions.In the deposition reformation regions(transition form type),the topography has strong undulations,the sediments are coarse,tidal sand ridges are well-developed at terrigenoussupplied estuaries and convergence zones,and the Holocene sediments are thick,transformed by tides,river runoff,and currents.展开更多
Two new species of free living nematodes Tripyloides mangrovensis n.sp.and Tripyloides amoyanus n.sp.of genus Tripyloides de Man,1886 are described from mangroves of the Tong’an Bay and Haimen Island in the Xiamen Ba...Two new species of free living nematodes Tripyloides mangrovensis n.sp.and Tripyloides amoyanus n.sp.of genus Tripyloides de Man,1886 are described from mangroves of the Tong’an Bay and Haimen Island in the Xiamen Bay,China.The two species are both characterized by six stout outer labial setae,male without preanal papillae,tail conico-cylindrical without swollen terminally.Tripyloides mangrovensis n.sp.can be additionally by its buccal cavity consisting of two parts,amphid circular,distinct proximal conical and distal slender cylindrical portions,2/3 of the tail cylindrical.Tripyloides amoyanus n.sp.is distinguished by buccal cavity consisting of three parts with small tooth,amphid small,rounded,like a comma-shaped loop,1/3 of the tail cylindrical gubernaculum with four denticles.展开更多
Extensive shrimp ponds are located next to the landward edges of most of mangrove forests in China. A shrimp pond may influence mangroves by(1) routine effluent between pond and tide, and(2) dredging effluent from pon...Extensive shrimp ponds are located next to the landward edges of most of mangrove forests in China. A shrimp pond may influence mangroves by(1) routine effluent between pond and tide, and(2) dredging effluent from pond-dredging at least once a year. Our study consisted of two experiments to study the effects of these two effluents on the seedling growth of Kandelia obovata. One experiment simulated the effects of routine effluents.The other simulated four sedimentation thicknesses(0 cm, 2 cm, 4 cm, 8 cm) over mangrove soils by dredging effluent from pond-dredging, and revealed the cumulative effects of dredging effluents on K. obovata. At each of the three fixed salinities, i.e., 5, 15 and 25, routine effluent did not result in significant differences in each of the measured growth parameters of K. obovata seedlings. However, effects of dredging effluent on seedling growth of K. obovata were related with sedimentation thickness. Most growth parameters showed maximum values at sedimentation thickness 4 cm. The data indicated that K. obovata accelerated its growth under moderate sedimentation thicknesses and it was tolerant and adaptable to shrimp pond-cleaning effluent sediments up to about 8 cm in our experiment.展开更多
Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT a...Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.展开更多
Based on a hydrodynamic-ecological model, the temperature, salinity, current, phytoplankton(Chl a),zooplankton, and nutrient(dissolved inorganic nitrogen, DIN, and dissolved inorganic phosphorous, DIP)distributions in...Based on a hydrodynamic-ecological model, the temperature, salinity, current, phytoplankton(Chl a),zooplankton, and nutrient(dissolved inorganic nitrogen, DIN, and dissolved inorganic phosphorous, DIP)distributions in the Beibu Gulf were simulated and the nutrient budget of 2015 was quantitatively analyzed. The simulated results show that interface processes and monsoons significantly influence the ecological processes in the gulf. The concentrations of DIN, DIP, phytoplankton and zooplankton are generally higher in the eastern and northern gulf than that in the western and southern gulf. The key regions affected by ecological processes are the Qiongzhou Strait in winter and autumn and the estuaries along the Guangxi coast and the Red River in summer.In most of the studied domains, biochemical processes contribute more to the nutrient budget than do physical processes, and the DIN and DIP increase over the year. Phytoplankton plays an important role in the nutrient budget;phytoplankton photosynthetic uptake is the nutrient sink, phytoplankton dead cellular release is the largest source of DIN, and phytoplankton respiration is the largest source of DIP. The nutrient flux in the connected sections of the Beibu Gulf and open South China Sea(SCS) inflows from the east and outflows to the south. There are 113 709 t of DIN and 5 277 t of DIP imported from the open SCS to the gulf year-around.展开更多
Mangroves are unique in their biodiversity,but studies on their meiobenthic biodiversity in China are scarce.Despite the importance of mangroves,little work has been done on the classification of nematodes in mangrove...Mangroves are unique in their biodiversity,but studies on their meiobenthic biodiversity in China are scarce.Despite the importance of mangroves,little work has been done on the classification of nematodes in mangrove wetlands.Fujian Province is the most northern point of China’s natural mangrove distribution,and it is also one of the provinces with the earliest constructed mangrove forest.In this paper,two new free-living marine nematode species of Desmodoridae from the Xiamen mangrove wetlands in China are described.Metachromadora xiamenensis sp.nov.is characterized by a cylindrical body,and smooth head capsule set off from the rest of the body.The cuticle is finely annulated and thickened at the midbody.Lateral ridges run from the posterior end of the pharynx to the middle of the tail.The amphid foveae is loop shaped and opens at the top with a double contour amphidial,pharynx with bipartite cuticularized internal cavity.There are 18 tubular precloacal supplements and tail with three small protuberances.Molgolaimus euryformis sp.nov.is characterized by a relatively short and plump body with finely annulated cuticle,which is particularly obvious in the tail.The head is small and wide with intensive striates.The inner and outer labial sensilla are indistinct with short spicules and ventral apophysis,a gubernaculum with a block-shaped hook,a swollen conical-cylindrical tail and an absence of precloacal supplements.展开更多
To compare meiofaunal community in the two mangrove wetlands in Tong'an Bay, Xiamen, China, and probe the response of meiofauna to high organic matter, sampling was carried out in Fenglin and Xiang'an mangrove...To compare meiofaunal community in the two mangrove wetlands in Tong'an Bay, Xiamen, China, and probe the response of meiofauna to high organic matter, sampling was carried out in Fenglin and Xiang'an mangrove wetlands in the bay. The results showed that the Ne/Co ratio(nematode to benthic copepod) and organic matter in Fenglin mangrove wetland were higher than those in Xiang'an mangrove wetland. The meiofaunal abundance in Fenglin mangrove was all lower than that in Xiang'an mangrove wetland in summer, autumn and spring, while the meiofaunal abundance in Fenglin mangrove was higher than that in Xiang'an mangrove wetland in winter. Two-way ANOVA results showed that the meiofaunal abundance and nematode abundance were significantly different between regions, seasons and region×season. With all the results in the present study, we confirmed that the positive response of meiofaunal and nematode abundance were only detected for medium organic matter contents according to the Xiang'an wetland's level, and that the distribution of meiofaunal abundance would be influenced by sand content. Higher copepod abundance and lower N/C value usually suggest better environmental quality.展开更多
After the United Nations Agenda 2030 was officially launched in September 2015,governments around the world have taken actions to implement the ambitious plan.This paper summarizes the actions and policies taken in Ch...After the United Nations Agenda 2030 was officially launched in September 2015,governments around the world have taken actions to implement the ambitious plan.This paper summarizes the actions and policies taken in China for promoting the implementation of the UN’2030 Agenda for Sustainable Development,with emphasis on promoting the development of demonstration zones for delivery of the Sustainable Development Goals(SDGs).The Chinese government has taken two types of measures.One is to formulate a series of national plans and strategies and the other is to construct pilot and demonstration zones.Two approaches were presented to optimize the selection criteria for demonstration zones:a problem-based approach;and a major function-based approach.Both provided priority regions and major themes for selection and construction of demonstration zones.Suggestions for promoting the development of demonstration zones include:(1)building a monitoring system for the implementation of SDGs in each demonstration zone and establishing an open online platform to track the progress;(2)forming an effective stakeholder participation mechanism.The experiences in constructing innovation-driven demonstration zones are insightful for other countries to take practical actions in the delivery of SDGs.展开更多
The Gross growth efficiency(GGE) is defined as the amount of consumer carbon produced relative to the amount of prey ingested in a given time interval. In population ecology, it can be considered as an index for the a...The Gross growth efficiency(GGE) is defined as the amount of consumer carbon produced relative to the amount of prey ingested in a given time interval. In population ecology, it can be considered as an index for the ability of a consumer to convert the biomass of food into its population production. In this study, it was firstly applied to estimate the role of amphipods grazing in the biomass dynamics of macroalgae(Ulva lactuca) in Yundang Lagoon(a subtropical eutrophic coastal lagoon, Xiamen City, China). It was found that amphipods were the dominant group(82.2%–98.7%) in the benthic assemblage, in which five amphipod species(Corophium uenoi, Ampithoe valida, Grandidierella japonica, Grammaropsis laevipalmata and Caprella panantis) were observed in the lagoon. However, only A. valida significantly consumed U. lactuca among these amphipod species. A series of experiments were conducted to estimate the consumption of U. lactuca by A. valida. It was suggested that the monthly secondary production(P) of A. valida using size frequency method ranged from 2.39 to 13.68 g/m2. GGE of A. valida exponentially reduced with body size and was closely associated with water temperature. Therefore, GGE equation for different months using the temperature recorded during the field investigation was fitted. The monthly consumption of U. lactuca was figured out to be 86.7–1 549.0 g/m2 by the sum of consumption(P/GGE) by A. valida at different size, accounting for 2.0%–37.5% of U. lactuca production. It indicates that the grazing effect of A. valida did play a role in reducing the accumulation of U. lactuca biomass when A. valida was abundant, but it finally fails to limit the U. lactuca growth in Yundang Lagoon. Low abundance of A. valida and high nutrient loading may be two major reasons for the outbreak of U. lactuca bloom in the lagoon.展开更多
The radionuclide ^(210) Pb is suitable for century-scale dating and has been used to calculate the sedimentation rate in a variety of environments. However, two common ways to apply 210 Pb dating techniques may give m...The radionuclide ^(210) Pb is suitable for century-scale dating and has been used to calculate the sedimentation rate in a variety of environments. However, two common ways to apply 210 Pb dating techniques may give misleading results. One is "prolonging of age", i.e., using the calculated sedimentation rate to date back to 200 or 300 years.This practice must be treated with caution because the 210 Pb dating techniques do not guarantee direct dating for ages much older than 100 years. Another is "loss of age", i.e., the calculated time span between the topmost layer and the 210 Pb background layer in cores is less than 100 years when an apparent sedimentation rate is used in the calculation. Here, we propose that based on the principle of 210 Pb dating, the upper limit of age suitable for direct210 Pb dating is between 110 and 155 years. The "prolonging" application is acceptable only if the sedimentary environment in the past several hundred years was stable and the sedimentation rate was generally constant, and verification with independent evidence(such as historical records or biomarker methodology) is needed.Furthermore, after analyzing many published and collected data, we found four possible reasons for the "loss of age". First, the compaction effect of sediment should be corrected in laboratory analysis or else the calculated age will be underestimated. Second, the accuracy and uncertainty of 210 Pb activity measurement affect the judgment of the background. To be cautious, researchers are apt to choose a background activity with a younger age. Third,use of a slightly smaller value of supported 210 Pb activity in a calculation will lead to considerable underestimation of the time span. Finally, later-stage erosion and migration are common for sedimentation, which lead to loss of sedimentary records and are often reflected as a "loss of age" in cores. We believe that proper use of 210 Pb dating data may provide helpful information on our understanding of sediment records and recent environmental changes.展开更多
In order to realize the spatiotemporal variations of benthic macrofaunal communities at the"Amphioxus Sand"habitat,six surveys including four seasons and three consecutive summers(i.e.,2014,2015 and 2016)wer...In order to realize the spatiotemporal variations of benthic macrofaunal communities at the"Amphioxus Sand"habitat,six surveys including four seasons and three consecutive summers(i.e.,2014,2015 and 2016)were conducted in two core sites,i.e.,Huangcuo(HC)and Nanxian-Shibaxian(NX),in the Xiamen Amphioxus Nature Reserve in China.A total of 155 species of macrofauna were recorded,therein,polychaetes were dominant in terms of species number and density.Significant spatiotemporal variations of macrofaunal communities were observed.The density of polychaetes and the biomass of molluscs in the HC site were higher than those in the NX site.Macrofauna were more diverse and abundant in the cold seasons(winter and spring)than that in the warm seasons(summer and autumn).The annual variations of macrofaunal communities may be attributed to the changes in sediment texture among the three years of the survey.The variations in macrofaunal communities were mainly related to the proportion of polychaetes within the community.In addition,the density of amphioxus(include Branchiostoma japonicum and B.belcheri)was negatively correlated to that of polychaetes,bivalves,and crustaceans.Amphioxus was less likely to be found in the sediments with higher silt and clay content.Five biotic indices including Margaref’s richness index(d),Peilou’s evenness index(J′),Shannon-Wiener diversity index(H′),AMBI and M-AMBI were calculated in the present study.AMBI seems suitable in assessing benthic health at the"Amphioxus Sand"habitat,and a potential risk of ecological health in Xiamen Amphioxus Nature Reserve should be aware.展开更多
Mangrove forests are vulnerably threatened by sea level rise(SLR).Vegetation organic carbon(OC)stocks are important for mangrove ecosystem carbon cycle.It is critical to understand how SLR affects vegetation OC stocks...Mangrove forests are vulnerably threatened by sea level rise(SLR).Vegetation organic carbon(OC)stocks are important for mangrove ecosystem carbon cycle.It is critical to understand how SLR affects vegetation OC stocks for evaluating mangrove blue carbon budget and global climate change.In this study,biomass accumulation and OC stocks of mangrove vegetation were compared among three 10 year-old Kandelia obovata(a common species in China)mangrove forests under three intertidal elevations through species-specific allometric equations.This study simulated mangrove forests with SLR values of 0 cm,40 cm and 80 cm,respectively,representing for the current,future~100 a and future~200 a SLR of mangrove forests along the Jiulong River Estuary,China.SLR directly decreased mangrove individual density and inhibited the growth of mangrove vegetation.The total vegetation biomasses were(12.86±0.95)kg/m^2,(7.97±0.90)kg/m^2 and(3.89±0.63)kg/m^2 at Sites SLR 0 cm,SLR40 cm and SLR 80 cm,respectively.The total vegetation OC stock decreased by approximately 3.85 kg/m^2(in terms of C)from Site SLR 0 cm to Site SLR 80 cm.Significantly lower vegetation biomass and OC stock of various components(stem,branch,leaf and root)were found at Site SLR 80 cm.Annual increments of vegetation biomass and OC stock also decreased with SLR increase.Moreover,significant lower sedimentation rate was found at Site SLR 80 cm.These indicated that SLR will decrease mangrove vegetation biomass and OC stock,which may reduce global blue carbon sink by mangroves,exacerbate global warming and give positive feedback to SLR.展开更多
Background:The vulnerable Chinese Egret(Egretta eulophotes)is a long-distance migratory waterbird whose migration and wintering information is poorly understood.This study aims to identify the autumn migration routes ...Background:The vulnerable Chinese Egret(Egretta eulophotes)is a long-distance migratory waterbird whose migration and wintering information is poorly understood.This study aims to identify the autumn migration routes and wintering areas of juvenile Chinese Egrets and determine the migration movement traits of this species.Methods:Thirty-nine juvenile Chinese Egrets from the Fantuozi Island,an uninhabited offshore island with a large breeding colony of Chinese Egrets in Dalian,China,were tracked using GPS/GSM transmitters.Some feathers from each tracked juvenile were collected for molecular identification of sex in the laboratory.The GPS locations,recorded at 2-h intervals from August 2018 to May 2020,were used for the analyses.Results:Of the 39 tracked juveniles,30 individuals began their migration between September and November,and 13 successfully completed their autumn migration between October and November.The juveniles migrated southward via three migration routes,coastal,oceanic and inland,mainly during the night.The migration duration,migration distance,flight speed,and stopover duration of the 13 juvenile egrets that completed migration averaged 5.08±1.04 days,3928.18±414.27 km,57.27±5.73 km/h,and 23.08±19.28 h,respectively.These juveniles wintered in the coastal wetlands of Southeast Asia including those in the Philippines,Vietnam,and Malaysia,and only one successfully began its spring migration in June 2020.Conclusions:This study newly finds that the oceanic route taken by juvenile Chinese Egrets,suggesting that the juveniles are able to fly over the Pacific Ocean without a stopover.Moreover,our novel data indicate that coastal wetlands along the East Asian-Australasian Flyway are important areas for both autumn migration stopover and the wintering of these juveniles,suggesting that international cooperation is important to conserve the vulnerable Chinese Egret and the wetland habitats on which it depends.展开更多
Background: Noninvasive and nondestructive DNA sampling techniques are becoming more important in genetic studies because they can provide genetic material from wild animals with less or even without disturbance,which...Background: Noninvasive and nondestructive DNA sampling techniques are becoming more important in genetic studies because they can provide genetic material from wild animals with less or even without disturbance,which is particularly useful for the study of endangered species,i.e.,birds.However,nondestructively and noninvasively sampled DNA may,in some cases,be inadequate in the amount and quality of the material collected,which can lead to low amplification success rates and high genotyping errors.Methods: In this study,noninvasive(eggshell swab,shed feather and feces),nondestructive(plucked feather and buccal swab) and invasive(blood) DNA samples were collected from the vulnerable Chinese Egret(Egretta eulophotes).DNA concentrations,PCR amplification success and microsatellite genotyping errors of different sample types were evaluated and compared to determine whether noninvasive and nondestructive samples performed as well as invasive samples in our experimental procedures.Results: A total of 159 samples were collected in the field.Among the different sample types,the highest DNA concentrations(154.0–385.5 ng/μL) were obtained from blood.Those extracted from fecal samples were the lowest,ranging from 1.25 to 27.5 ng/μL.Almost all of the DNA samples,i.e.,95.59 %,were successfully amplified for mt DNA(n = 152) and 92.76 % of mt DNA samples were successfully genotyped for at least five of the nine microsatellite loci tested(n = 141).Blood samples and buccal swabs produced reliable genotypes with no genotyping errors,but in feces,allelic dropouts and false alleles occurred in all nine loci,with error rates ranging from 6.67 to 38.10 % for the dropouts and from 6.06 to 15.15 % for the false alleles.Conclusions: These results indicate that both nondestructive and noninvasive samplings are suitable for avian microsatellite genotyping,save for fecal DNA.However,we should remain cautious of the appearance of genotyping errors,especially when using noninvasive material.展开更多
基金The National Natural Science Foundation of China under contract Nos 42076142 and 41776097the Provincial Natural Science Foundation of Fujian under contract No.2020J06030the Fund of Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration under contract No.EPR2020003.
文摘Mangrove forests are under the stress of sea level rise(SLR)which would affect mangrove soil biogeochemistry.Mangrove soils are important sources of soil-atmosphere greenhouse gas(GHG)emissions,including carbon dioxide(CO_(2)),methane(CH_(4))and nitrous oxide(N_(2)O).Understanding how SLR influences GHG emissions is critical for evaluating mangrove blue carbon capability.In this study,potential effects of SLR on the GHG emissions were quantified through static closed chamber technique among three sites under different intertidal elevations,representing tidal flooding situation of SLR values of 0 cm,40 cm and 80 cm,respectively.Compared with Site SLR 0 cm,annual CO_(2) and N_(2)O fluxes decreased by approximately 75.0%and 27.3%due to higher soil water content,lower salinity and soil nutrient environments at Site SLR 80 cm.However,CH_(4) fluxes increased by approximately 13.7%at Site SLR 40 cm and 8.8%at Site SLR 80 cm because of lower salinity,higher soil water content and soil pH.CO_(2)-equivalent fluxes were 396.61 g/(m^(2)·a),1423.29 g/(m^(2)·a)and 1420.21 g/(m^(2)·a)at Sites SLR 80 cm,SLR 40 cm and SLR 0 cm,respectively.From Site SLR 0 cm to Site SLR 80 cm,contribution rate of N_(2)O and CH_(4) increased by approximately 7.42%and 3.02%,while contribution rate of CO_(2) decreased by approximately 10.44%.The results indicated that warming potential of trace CH_(4) and N_(2)O was non-negligible with SLR.Potential effects of SLR on the mangrove blue carbon capability should warrant attention due to changes of all three greenhouse gas fluxes with SLR.
基金the National Key Research and Development Program of China(No.2016YFC0502904)。
文摘In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic aromatic hydrocarbon(PAHs),organic carbon and nitrogen were seasonally investigated at site A(with horseshoe crab presence),sites B and C(without horseshoe crab presence)in the Crocodile Island intertidal zone in Xiamen from June 2018 to July 2019.The results showed that most of the community parameters of benthic macrofauna,population parameters of common benthic macrofauna and environmental parameters were significantly different at the sites with horseshoe crab versus non-horseshoe crab sites.A two-way ANOVA test showed that the densities of Ceratonereis erythraeensis and Sigambra hanaokai had significant site variation.Cluster and nonmetric multi-dimensional scaling(NMDS)analysis showed the community composition of benthic macrofauna was significantly different among the three sampling sites over four seasons.The mean sand content at site A(64.32%)was higher than those at site B(36.01%)and site C(18.86%).Conversely,the mean contents of silt,clay,Cr,Co,Ni,organic carbon,organic nitrogen,phenanthrene,and pyrene at site A were lower than those at site B and site C.These observations are consistent with the expected preferences of horseshoe crabs to live in areas with 60%sand content,which is associated with abundant and edible clamworms in the Crocodile Island intertidal zone,Xiamen.
基金The National Nature Science Foundation of China under contract Nos 40925018 and 41176112the National Basic Research Program(973 Program)of China under contract No.2009CB421203
文摘In order to determine the phytoplankton community composition, the modification and optimizing of the CHEMical TAXonomy(CHEMTAX) running was carried out through samples grouping, successive run and evaluate the results for HPLC-pigment samples in the South China Sea(SCS). The vertical distribution of the ratio of pigment to total Chl a(TChl a) exhibited three different patterns, including increasing with depth pattern(e.g., But-Fuco), decreasing with depth pattern(e.g., Zea) and increasing at deep chlorophyll maximum(DCM) pattern(e.g., Hex-Fuco). The vertical profiles for Fuco/TChl a and Pras/TChl a was higher in coast than in the shelf and basin, and the Zea and Dv-Chl a expressed conversely. So the samples in the coastal stations must be separated for the cluster analysis group procedure in the SCS. Successive run was introduced into the CHEMTAX calculation and the output results were evaluated by the convergence of pigment/TChl a ratios. Most of the ratios were well converged at the fifth running, except Zea/TChl a for Prochlorococcus and Chl b/TChl a for prasinophytes and so on. To evaluate the fifth running's results, haptophytes_8 and chlorophytes were two phytoplankton groups with much uncertainty. But the fifth estimated value was better than running once was supported by the regression evidence between the measured pigment concentration and calculation values. Synechococcus was another component with much mutability, and the CHEMTAX's result should be compared to the flow cytometry's cell abundance.
基金supported by Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LY18C030001 and LQ13C030002)National Natural Science Foundation of China(Grant No.41776097)+4 种基金Special Funding for Research of National Oceanic Public Service Industry of China(Grant No.201505028)National Science and Technology Basic Resources Survey Special of China(Grant No.2017FY100700)Zhejiang Province Science and Technology Plan Project of China(Grant Nos.2013C25096 and2014F50003)Zhejiang Province Foundation of the Nonprofit Technology Research Projects of China(Grant No.2015C33227)Wenzhou Municipal Science and Technology Plan Project of China(Grant Nos.N20140046,N20170008 and S20160004)
文摘As the most northerly mangrove species in China, Kandelia obovata may undergo extreme cold event stress. Enhancing the cold tolerance of this species is crucial to its successful afforestation. This study aimed to determine the resistance of K. obovata seedlings to low temperature stress by cold acclimation and to explain the mechanisms for alleviating cold injury. To understand these mechanisms, seedlings that were acclimatized and not acclimatized were exposed to 5℃/- 2℃(day/night)for 48 h.Results showed that low temperature stress reduced leaf photosynthesis of non-acclimatized seedlings by inducing oxidative stress and structural damage to chloroplasts. These phenomena were shown by increasing levels of malondialdehyde (MDA), O2-and H2O2, as well as decreasing enzyme activities in the ascorbate–glutathione (AsA-GSH) cycle. However, cold-acclimatized seedlings had improved photosynthetic rates and efficiency of photosystem II (PSII) under low temperature stress. Compared with non-acclimatized seedlings, leaves of coldacclimatized seedlings under low temperature stress for 48 h exhibited higher anti-oxidative enzyme activities, lower levels of O2^- and H2O2, less damage to chloroplast structure, and removed 33.7% of MDA at low temperature stress for 48 h. The data indicate that cold acclimation enhances photosynthetic capacity by effectively regulating activation in the PSII electron transport and the AsA–GSH cycle to scavenge excess ROS in chloroplasts, while the latter is more important.
基金The National Natural Science Foundation of China under contract Nos 42106005,91958203,41676131,41876155.
文摘The classification of the springtime water mass has an important influence on the hydrography,regional climate change and fishery in the Taiwan Strait.Based on 58 stations of CTD profiling data collected in the western and southwestern Taiwan Strait during the spring cruise of 2019,we analyze the spatial distributions of temperature(T)and salinity(S)in the investigation area.Then by using the fuzzy cluster method combined with the T-S similarity number,we classify the investigation area into 5 water masses:the Minzhe Coastal Water(MZCW),the Taiwan Strait Mixed Water(TSMW),the South China Sea Surface Water(SCSSW),the South China Sea Subsurface Water(SCSUW)and the Kuroshio Branch Water(KBW).The MZCW appears in the near surface layer along the western coast of Taiwan Strait,showing low-salinity(<32.0)tongues near the Minjiang River Estuary and the Xiamen Bay mouth.The TSMW covers most upper layer of the investigation area.The SCSSW is mainly distributed in the upper layer of the southwestern Taiwan Strait,beneath which is the SCSUW.The KBW is a high temperature(core value of 26.36℃)and high salinity(core value of 34.62)water mass located southeast of the Taiwan Bank and partially in the central Taiwan Strait.
基金The National Natural Science Foundation of China under contract Nos 42076042 and 41721005the Fund of Ministry of Science and Technology of China under contract No.2017FY201403the Fund of China Ocean Mineral Resources R&D Association under contract No.DY135-13-E2-03.
文摘Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.
基金granted by the National Science Foundation of China (No. 41276058)the project of integrated achievement on investigation of submarine topography and geomorphology in offshore China (No. 908-ZC-I-07)the State Oceanic Administration public welfare research project (No. 201105001, No. 2012418004)
文摘Based on the latest submarine topography data of the China 908 Project(China offshore marine environmental comprehensive investigation and assessment),we analyzed the general China offshore submarine topographical characteristics and the factors influencing its development.The submarine topography off the coast of China follows the NW-SE trend of the land topography.The gradient of the submarine topography ranges from 0.2%to 1.6%with an average gradient of about0.8%.The depth contours run mostly parallel to the coast,and extend out to sea in estuary areas.The submarine topography is dominated by the geological structure,which shows the typical characteristics of two uplifts and two subsidence events from north to south.The geological structure combined with the different sedimentary environments and complex hydrodynamic conditions produced topography that can be characterized by three types:sedimentary basins,compressionuplift,and transition form.In the sedimentary basin and compression-uplift regions,the topographical undulation is small,sediments are fine-grained,and the currents flow in a single direction,leading to bays with sedimentary plains and underwater accumulation slopes,which are of the same tectonic origin.Transition-type topography is characterized by strong undulations and mixed-size sediment particles,terraces and scarps inshore and shelf plains and erosion-deposition landforms offshore.This is a result of incomplete fault block development and repeated transgressions.In the deposition reformation regions(transition form type),the topography has strong undulations,the sediments are coarse,tidal sand ridges are well-developed at terrigenoussupplied estuaries and convergence zones,and the Holocene sediments are thick,transformed by tides,river runoff,and currents.
基金The National Natural Science Foundation of China under contract No.41376113the Public Science and Technology Research Funds Projects of Ocean under contract No.201505004the National Key Research and Development Program of China under contract No.2016YFC0502900
文摘Two new species of free living nematodes Tripyloides mangrovensis n.sp.and Tripyloides amoyanus n.sp.of genus Tripyloides de Man,1886 are described from mangroves of the Tong’an Bay and Haimen Island in the Xiamen Bay,China.The two species are both characterized by six stout outer labial setae,male without preanal papillae,tail conico-cylindrical without swollen terminally.Tripyloides mangrovensis n.sp.can be additionally by its buccal cavity consisting of two parts,amphid circular,distinct proximal conical and distal slender cylindrical portions,2/3 of the tail cylindrical.Tripyloides amoyanus n.sp.is distinguished by buccal cavity consisting of three parts with small tooth,amphid small,rounded,like a comma-shaped loop,1/3 of the tail cylindrical gubernaculum with four denticles.
基金The National Key Research and Development Program of China under contract No.2017YFC0506103the National Natural Science Foundation of China under contract Nos 41776097 and 41076049Zhejiang Provincial Natural Science Foundation of China under contract No.LY18C030001
文摘Extensive shrimp ponds are located next to the landward edges of most of mangrove forests in China. A shrimp pond may influence mangroves by(1) routine effluent between pond and tide, and(2) dredging effluent from pond-dredging at least once a year. Our study consisted of two experiments to study the effects of these two effluents on the seedling growth of Kandelia obovata. One experiment simulated the effects of routine effluents.The other simulated four sedimentation thicknesses(0 cm, 2 cm, 4 cm, 8 cm) over mangrove soils by dredging effluent from pond-dredging, and revealed the cumulative effects of dredging effluents on K. obovata. At each of the three fixed salinities, i.e., 5, 15 and 25, routine effluent did not result in significant differences in each of the measured growth parameters of K. obovata seedlings. However, effects of dredging effluent on seedling growth of K. obovata were related with sedimentation thickness. Most growth parameters showed maximum values at sedimentation thickness 4 cm. The data indicated that K. obovata accelerated its growth under moderate sedimentation thicknesses and it was tolerant and adaptable to shrimp pond-cleaning effluent sediments up to about 8 cm in our experiment.
基金Supported by the National Key Basic Research Development Program of China(973 Program)(No.2015CB453303)the National Science Foundation for Young Scientists of China(No.41606195)。
文摘Fish otolithδ^(15) N(δ^(15) N_(oto))is a demonstrated source of information of dietary history for marine fi sh as it is available iN_(oto)lith archives and sedimentary deposits unlike white muscle tissue(WMT).WMT and stomach content data are insufficient for trophic level(TL)data of past fi shes which is important for the changes of marine fi shery resources over long time scales.To determine the correlation betweenδ^(15) N_(oto) and fi sh WMTδ^(15) N(δ^(15) N_(wmt))and the feasibility of usingδ^(15) N_(oto) in characterizing the TLs of marine fi shes,we conducted nitrogen stable isotope analysis(SIA)in the otolith and WMT of 36 marine fi sh species sampled from the Yellow Sea and northern East China Sea in 2011-2014.Bothδ^(15) N_(oto) andδ^(15) N_(wmt) were analyzed using an elemental analyzer coupled with an isotope ratio mass spectrometer(EA-IRMS).Multiple otoliths were combined to make each otolith measurement and were analyzed as-is without a carbonate dissolution pre-processing step.δ^(15) N_(oto) andδ^(15) N_(wmt) comparisons for species in the Yellow Sea and northern East China Sea are currently lacking and would be helpful for both regional studies and for increasing the number of species for whichδ^(15) N_(oto) andδ^(15) N_(wmt) have been compared.Additionally,to determine the relative accuracy of trophic level calculated usingδ^(15) N_(oto),we compared TL calculated fromδ^(15) N_(oto) to traditional trophic level metrics calculated usingδ^(15) N_(wmt).The results showed a positive and highly signifi cant correlation(R=0.780,P<0.001)betweenδ^(15) N_(oto) andδ^(15) N_(wmt).Trophic level estimation using WMT(TL wmt)and otolith(TL oto)showed congruence in our study,which is not entirely surprising given thatδ^(15) N_(oto) was regressed againstδ^(15) N_(wmt) and the resulting regression coefficient was used to convertδ^(15) N_(oto) toδ^(15) N_(wmt) prior to calculating TL oto.This conversion was required in order to be consistent with previousδ^(15) N_(wmt)-based calculations of TL for comparison.TL oto calculations resulted in TL values that were largely within 5%-10%of TL values calculated withδ^(15) N_(wmt).Our fi ndings show thatδ^(15) N_(oto) is a feasible technique for characterizing the TLs of marine fi sh and can also assist in food web and marine ecosystem studies.
基金The National Key Research and Development Program of China under contract No.2017YFC1404801the Program of Xiamen Southern Oceanographic Center under contract No.15PZB009NF05。
文摘Based on a hydrodynamic-ecological model, the temperature, salinity, current, phytoplankton(Chl a),zooplankton, and nutrient(dissolved inorganic nitrogen, DIN, and dissolved inorganic phosphorous, DIP)distributions in the Beibu Gulf were simulated and the nutrient budget of 2015 was quantitatively analyzed. The simulated results show that interface processes and monsoons significantly influence the ecological processes in the gulf. The concentrations of DIN, DIP, phytoplankton and zooplankton are generally higher in the eastern and northern gulf than that in the western and southern gulf. The key regions affected by ecological processes are the Qiongzhou Strait in winter and autumn and the estuaries along the Guangxi coast and the Red River in summer.In most of the studied domains, biochemical processes contribute more to the nutrient budget than do physical processes, and the DIN and DIP increase over the year. Phytoplankton plays an important role in the nutrient budget;phytoplankton photosynthetic uptake is the nutrient sink, phytoplankton dead cellular release is the largest source of DIN, and phytoplankton respiration is the largest source of DIP. The nutrient flux in the connected sections of the Beibu Gulf and open South China Sea(SCS) inflows from the east and outflows to the south. There are 113 709 t of DIN and 5 277 t of DIP imported from the open SCS to the gulf year-around.
基金funded by the National Natural Science Foundation of China (No. 41606119)the Provincial Natural Science Foundation of Fujian (No. 2017J05068)the New Century Outstanding Talents Support Program for Institutions of Higher Learning in Fujian Province and Building Ecological Security for Urban Agglomeration and Integrating Ecological Restoration Techniques for Coastal Zones in Fujian River Deltas (No. 2016YFC0502900)
文摘Mangroves are unique in their biodiversity,but studies on their meiobenthic biodiversity in China are scarce.Despite the importance of mangroves,little work has been done on the classification of nematodes in mangrove wetlands.Fujian Province is the most northern point of China’s natural mangrove distribution,and it is also one of the provinces with the earliest constructed mangrove forest.In this paper,two new free-living marine nematode species of Desmodoridae from the Xiamen mangrove wetlands in China are described.Metachromadora xiamenensis sp.nov.is characterized by a cylindrical body,and smooth head capsule set off from the rest of the body.The cuticle is finely annulated and thickened at the midbody.Lateral ridges run from the posterior end of the pharynx to the middle of the tail.The amphid foveae is loop shaped and opens at the top with a double contour amphidial,pharynx with bipartite cuticularized internal cavity.There are 18 tubular precloacal supplements and tail with three small protuberances.Molgolaimus euryformis sp.nov.is characterized by a relatively short and plump body with finely annulated cuticle,which is particularly obvious in the tail.The head is small and wide with intensive striates.The inner and outer labial sensilla are indistinct with short spicules and ventral apophysis,a gubernaculum with a block-shaped hook,a swollen conical-cylindrical tail and an absence of precloacal supplements.
基金supported by the National Natural Science Foundation of China(Grant No.41176089)supported by WEL(abbreviation of Key Laboratory of the Coastal and Wetland Ecosystems,Ministry of Education)Visiting Fellowship Program from Xiamen University
文摘To compare meiofaunal community in the two mangrove wetlands in Tong'an Bay, Xiamen, China, and probe the response of meiofauna to high organic matter, sampling was carried out in Fenglin and Xiang'an mangrove wetlands in the bay. The results showed that the Ne/Co ratio(nematode to benthic copepod) and organic matter in Fenglin mangrove wetland were higher than those in Xiang'an mangrove wetland. The meiofaunal abundance in Fenglin mangrove was all lower than that in Xiang'an mangrove wetland in summer, autumn and spring, while the meiofaunal abundance in Fenglin mangrove was higher than that in Xiang'an mangrove wetland in winter. Two-way ANOVA results showed that the meiofaunal abundance and nematode abundance were significantly different between regions, seasons and region×season. With all the results in the present study, we confirmed that the positive response of meiofaunal and nematode abundance were only detected for medium organic matter contents according to the Xiang'an wetland's level, and that the distribution of meiofaunal abundance would be influenced by sand content. Higher copepod abundance and lower N/C value usually suggest better environmental quality.
基金supported by the National Key R&D Program of China(2019YFC0507505,2017YFC0505704)the National Natural Science Foundation of China(Grant No.71761147001).
文摘After the United Nations Agenda 2030 was officially launched in September 2015,governments around the world have taken actions to implement the ambitious plan.This paper summarizes the actions and policies taken in China for promoting the implementation of the UN’2030 Agenda for Sustainable Development,with emphasis on promoting the development of demonstration zones for delivery of the Sustainable Development Goals(SDGs).The Chinese government has taken two types of measures.One is to formulate a series of national plans and strategies and the other is to construct pilot and demonstration zones.Two approaches were presented to optimize the selection criteria for demonstration zones:a problem-based approach;and a major function-based approach.Both provided priority regions and major themes for selection and construction of demonstration zones.Suggestions for promoting the development of demonstration zones include:(1)building a monitoring system for the implementation of SDGs in each demonstration zone and establishing an open online platform to track the progress;(2)forming an effective stakeholder participation mechanism.The experiences in constructing innovation-driven demonstration zones are insightful for other countries to take practical actions in the delivery of SDGs.
基金The Natural Science Foundation of Fujian Province under contract No.2014J01127the Public Science and Technology Research Funds Projects of Ocean under contract Nos 201205009-3 and 201105012
文摘The Gross growth efficiency(GGE) is defined as the amount of consumer carbon produced relative to the amount of prey ingested in a given time interval. In population ecology, it can be considered as an index for the ability of a consumer to convert the biomass of food into its population production. In this study, it was firstly applied to estimate the role of amphipods grazing in the biomass dynamics of macroalgae(Ulva lactuca) in Yundang Lagoon(a subtropical eutrophic coastal lagoon, Xiamen City, China). It was found that amphipods were the dominant group(82.2%–98.7%) in the benthic assemblage, in which five amphipod species(Corophium uenoi, Ampithoe valida, Grandidierella japonica, Grammaropsis laevipalmata and Caprella panantis) were observed in the lagoon. However, only A. valida significantly consumed U. lactuca among these amphipod species. A series of experiments were conducted to estimate the consumption of U. lactuca by A. valida. It was suggested that the monthly secondary production(P) of A. valida using size frequency method ranged from 2.39 to 13.68 g/m2. GGE of A. valida exponentially reduced with body size and was closely associated with water temperature. Therefore, GGE equation for different months using the temperature recorded during the field investigation was fitted. The monthly consumption of U. lactuca was figured out to be 86.7–1 549.0 g/m2 by the sum of consumption(P/GGE) by A. valida at different size, accounting for 2.0%–37.5% of U. lactuca production. It indicates that the grazing effect of A. valida did play a role in reducing the accumulation of U. lactuca biomass when A. valida was abundant, but it finally fails to limit the U. lactuca growth in Yundang Lagoon. Low abundance of A. valida and high nutrient loading may be two major reasons for the outbreak of U. lactuca bloom in the lagoon.
基金The National Natural Science Foundation of China under contract Nos 41376068 and 41776068
文摘The radionuclide ^(210) Pb is suitable for century-scale dating and has been used to calculate the sedimentation rate in a variety of environments. However, two common ways to apply 210 Pb dating techniques may give misleading results. One is "prolonging of age", i.e., using the calculated sedimentation rate to date back to 200 or 300 years.This practice must be treated with caution because the 210 Pb dating techniques do not guarantee direct dating for ages much older than 100 years. Another is "loss of age", i.e., the calculated time span between the topmost layer and the 210 Pb background layer in cores is less than 100 years when an apparent sedimentation rate is used in the calculation. Here, we propose that based on the principle of 210 Pb dating, the upper limit of age suitable for direct210 Pb dating is between 110 and 155 years. The "prolonging" application is acceptable only if the sedimentary environment in the past several hundred years was stable and the sedimentation rate was generally constant, and verification with independent evidence(such as historical records or biomarker methodology) is needed.Furthermore, after analyzing many published and collected data, we found four possible reasons for the "loss of age". First, the compaction effect of sediment should be corrected in laboratory analysis or else the calculated age will be underestimated. Second, the accuracy and uncertainty of 210 Pb activity measurement affect the judgment of the background. To be cautious, researchers are apt to choose a background activity with a younger age. Third,use of a slightly smaller value of supported 210 Pb activity in a calculation will lead to considerable underestimation of the time span. Finally, later-stage erosion and migration are common for sedimentation, which lead to loss of sedimentary records and are often reflected as a "loss of age" in cores. We believe that proper use of 210 Pb dating data may provide helpful information on our understanding of sediment records and recent environmental changes.
基金The National Key Research and Development Program of China under contract No.2016YFC0502904the Public Science and Technology Research Funds Projects of Oceans under contract No.201305030。
文摘In order to realize the spatiotemporal variations of benthic macrofaunal communities at the"Amphioxus Sand"habitat,six surveys including four seasons and three consecutive summers(i.e.,2014,2015 and 2016)were conducted in two core sites,i.e.,Huangcuo(HC)and Nanxian-Shibaxian(NX),in the Xiamen Amphioxus Nature Reserve in China.A total of 155 species of macrofauna were recorded,therein,polychaetes were dominant in terms of species number and density.Significant spatiotemporal variations of macrofaunal communities were observed.The density of polychaetes and the biomass of molluscs in the HC site were higher than those in the NX site.Macrofauna were more diverse and abundant in the cold seasons(winter and spring)than that in the warm seasons(summer and autumn).The annual variations of macrofaunal communities may be attributed to the changes in sediment texture among the three years of the survey.The variations in macrofaunal communities were mainly related to the proportion of polychaetes within the community.In addition,the density of amphioxus(include Branchiostoma japonicum and B.belcheri)was negatively correlated to that of polychaetes,bivalves,and crustaceans.Amphioxus was less likely to be found in the sediments with higher silt and clay content.Five biotic indices including Margaref’s richness index(d),Peilou’s evenness index(J′),Shannon-Wiener diversity index(H′),AMBI and M-AMBI were calculated in the present study.AMBI seems suitable in assessing benthic health at the"Amphioxus Sand"habitat,and a potential risk of ecological health in Xiamen Amphioxus Nature Reserve should be aware.
基金The National Natural Science Foundation of China under contract Nos 41776097 and 42076142the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources under contract No.2019017the Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration under contract No.EPR2020003。
文摘Mangrove forests are vulnerably threatened by sea level rise(SLR).Vegetation organic carbon(OC)stocks are important for mangrove ecosystem carbon cycle.It is critical to understand how SLR affects vegetation OC stocks for evaluating mangrove blue carbon budget and global climate change.In this study,biomass accumulation and OC stocks of mangrove vegetation were compared among three 10 year-old Kandelia obovata(a common species in China)mangrove forests under three intertidal elevations through species-specific allometric equations.This study simulated mangrove forests with SLR values of 0 cm,40 cm and 80 cm,respectively,representing for the current,future~100 a and future~200 a SLR of mangrove forests along the Jiulong River Estuary,China.SLR directly decreased mangrove individual density and inhibited the growth of mangrove vegetation.The total vegetation biomasses were(12.86±0.95)kg/m^2,(7.97±0.90)kg/m^2 and(3.89±0.63)kg/m^2 at Sites SLR 0 cm,SLR40 cm and SLR 80 cm,respectively.The total vegetation OC stock decreased by approximately 3.85 kg/m^2(in terms of C)from Site SLR 0 cm to Site SLR 80 cm.Significantly lower vegetation biomass and OC stock of various components(stem,branch,leaf and root)were found at Site SLR 80 cm.Annual increments of vegetation biomass and OC stock also decreased with SLR increase.Moreover,significant lower sedimentation rate was found at Site SLR 80 cm.These indicated that SLR will decrease mangrove vegetation biomass and OC stock,which may reduce global blue carbon sink by mangroves,exacerbate global warming and give positive feedback to SLR.
基金supported by the National Natural Science Foundation of China(Grant Nos.42076107,41676123,and 41476113)。
文摘Background:The vulnerable Chinese Egret(Egretta eulophotes)is a long-distance migratory waterbird whose migration and wintering information is poorly understood.This study aims to identify the autumn migration routes and wintering areas of juvenile Chinese Egrets and determine the migration movement traits of this species.Methods:Thirty-nine juvenile Chinese Egrets from the Fantuozi Island,an uninhabited offshore island with a large breeding colony of Chinese Egrets in Dalian,China,were tracked using GPS/GSM transmitters.Some feathers from each tracked juvenile were collected for molecular identification of sex in the laboratory.The GPS locations,recorded at 2-h intervals from August 2018 to May 2020,were used for the analyses.Results:Of the 39 tracked juveniles,30 individuals began their migration between September and November,and 13 successfully completed their autumn migration between October and November.The juveniles migrated southward via three migration routes,coastal,oceanic and inland,mainly during the night.The migration duration,migration distance,flight speed,and stopover duration of the 13 juvenile egrets that completed migration averaged 5.08±1.04 days,3928.18±414.27 km,57.27±5.73 km/h,and 23.08±19.28 h,respectively.These juveniles wintered in the coastal wetlands of Southeast Asia including those in the Philippines,Vietnam,and Malaysia,and only one successfully began its spring migration in June 2020.Conclusions:This study newly finds that the oceanic route taken by juvenile Chinese Egrets,suggesting that the juveniles are able to fly over the Pacific Ocean without a stopover.Moreover,our novel data indicate that coastal wetlands along the East Asian-Australasian Flyway are important areas for both autumn migration stopover and the wintering of these juveniles,suggesting that international cooperation is important to conserve the vulnerable Chinese Egret and the wetland habitats on which it depends.
基金supported by the National Natural Science Foundation of China(Grant nos. 41476113,31000963 and 31272333)the Fujian Natural Science Foundation of China (2010Y2007)
文摘Background: Noninvasive and nondestructive DNA sampling techniques are becoming more important in genetic studies because they can provide genetic material from wild animals with less or even without disturbance,which is particularly useful for the study of endangered species,i.e.,birds.However,nondestructively and noninvasively sampled DNA may,in some cases,be inadequate in the amount and quality of the material collected,which can lead to low amplification success rates and high genotyping errors.Methods: In this study,noninvasive(eggshell swab,shed feather and feces),nondestructive(plucked feather and buccal swab) and invasive(blood) DNA samples were collected from the vulnerable Chinese Egret(Egretta eulophotes).DNA concentrations,PCR amplification success and microsatellite genotyping errors of different sample types were evaluated and compared to determine whether noninvasive and nondestructive samples performed as well as invasive samples in our experimental procedures.Results: A total of 159 samples were collected in the field.Among the different sample types,the highest DNA concentrations(154.0–385.5 ng/μL) were obtained from blood.Those extracted from fecal samples were the lowest,ranging from 1.25 to 27.5 ng/μL.Almost all of the DNA samples,i.e.,95.59 %,were successfully amplified for mt DNA(n = 152) and 92.76 % of mt DNA samples were successfully genotyped for at least five of the nine microsatellite loci tested(n = 141).Blood samples and buccal swabs produced reliable genotypes with no genotyping errors,but in feces,allelic dropouts and false alleles occurred in all nine loci,with error rates ranging from 6.67 to 38.10 % for the dropouts and from 6.06 to 15.15 % for the false alleles.Conclusions: These results indicate that both nondestructive and noninvasive samplings are suitable for avian microsatellite genotyping,save for fecal DNA.However,we should remain cautious of the appearance of genotyping errors,especially when using noninvasive material.
