Lagrangian coherent structure analysis on transport of Acetes chinensis along coast of Lianyungang,China

Spatial heterogeneity or“patchiness”of plankton distributions in the ocean has always been an attractive and challenging scientific issue to oceanographers.We focused on the accumulation and dynamic mechanism of the Acetes chinensis in the Lianyungang nearshore licensed fishing area.The Lagrangian frame approaches including the Lagrangian coherent structures theory,Lagrangian residual current,and Lagrangian particle-tracking model were applied to find the transport pathways and aggregation characteristics of Acetes chinensis.There exist some material transport pathways for Acetes chinensis passing through the licensed fishing area,and Acetes chinensis is easy to accumulate in the licensed fishing area.The main mechanism forming this distribution pattern is the local circulation induced by the nonlinear interaction of topography and tidal flow.Both the Lagrangian coherent structure analysis and the particle trajectory tracking indicate that Acetes chinensis in the licensed fishing area come from the nearshore estuary.This work contributed to the adjustment of licensed fishing area and the efficient utilization of fishery resources.

Distribution,abundance,and realized niches of meroplankton by two different mesh size nets during spring 2017 in the Southern Yellow Sea,China

Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and evaluate the influence of varying mesh sizes(505 and 160μm)on the sampling efficiency of meroplankton,we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea(SYS).Our study revealed a total of 12 meroplankton groups,with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets.The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups.Furthermore,we focused on exploring the abundance,distribution patterns,and realized niches of meroplankton collected by the two mesh size nets,and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS.Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS.This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively.A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research.Our research significantly advances our understanding of the quantification,abundance,and distribution of meroplankton,serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.

Effect of Marine Planktonic Algal Particles on the Communication Performance of Underwater Quantum Link

As one of the main application directions of quantum technology,underwater quantum communication is of great research significance.In order to study the influence of marine planktonic algal particles on the communication performance of underwater quantum links,based on the extinction characteristics of marine planktonic algal particles,the influence of changes in the chlorophyll concentration and particle number density of planktonic algal particles on the attenuation of underwater links is explored respectively,the influence of marine planktonic algal particles on the fidelity of underwater quantum links,the generation rate of the security key,and the utilization rate of the channel is analyzed,and simulation experiments are carried out.The results show that with the increase in chlorophyll concentration and particle density of aquatic planktonic algal particles,quantum communication channel link attenuation shows a gradually increasing trend.In addition,the security key generation rate,channel fidelity and utilization rate are gradually decreasing.Therefore,the performance of underwater quantum communication channel will be interfered by marine planktonic algal particles,and it is necessary to adjust the relevant parameter values in the quantum communication system according to different marine planktonic algal particle number density and chlorophyll concentration to improve the performance of quantum communication.

Comparative study on composition and abundance of major planktons and physico-chemical characteristics among two ponds and Lake Tana,Ethiopia

Objective:To evaluate the difference in physico-chemical characteristics,composition and abundance of plankton communities owing to the supplementary feed added in fish ponds as compared to Lake Tana.Methods:Physico-chemical and biological data of plankton were collected from 3 studied sites from November 2008 to October 2009.Data were compared using One-way ANOVA to see the difference among sites.Diversity indices such as Margalef's index,Shannon-Wiener index,and evenness index were employed to describe the distribution of plankton community among the studied sites.Results:The pH value was remarkably higher in ponds water.However,conductivity and total dissolved solids were the highest in lake water.Nitrate concentration was relatively high in ponds.Zooplankton species richness was higher in lake water than ponds.The lake also had the highest mean value of both Shannon-Wiener index and evenness index in phytoplankton.Conclusions:The results revealed that the supplementary feed added to each pond had influence on nutrient content which enhanced algal biomass and productivity of the ponds.However,the pond water has to be regularly refreshed to control eutrophication.

Temporal change of plankton size structure preserved by Lugol's solution:a FlowCAM study

Plankton size structure is crucial for understanding marine ecosystem dynamics and the associated biogeochemical processes.A fixation step by acid Lugol’s solution has been commonly employed to preserve plankton samples in the field.However,the acid Lugol’s solution can bias the estimation of size structure and the preserved plankton size structure can vary with time.Here,we explore the impact of sample storage time on the size-structure of the plankton community preserved by Lugol’s solution.Two short-term experiments and one long-term experiment were conducted to explore the change of plankton community size structure with the storage time:covering from a week to a month,and to nearly seven months based on particle-size data obtained by continuous Flow Cytometer and Microscope(FlowCAM)measurements.We found a linear change of plankton size with the storage time in short-term periods(less than 3 months)with a decrease of the slope but an increase of the intercept for the normalized biomass size spectrum(NBS S).However,there were opposite trends for NBSS with increasing slope but decreasing intercept after3 months.The potential causes of the distinct patterns of the NBSS parameters are addressed in terms of the interplay between particle aggregation and fragmentation.We found large changes in plankton biovolume and abundance among different size classes,which may indicate a distinct effect of acid Lugol’s solution on various plankton size classes.The mechanism driving temporal change in the size-structure of the Lugolfixed plankton community was further discussed in terms of particle aggregation and fragmentation.Finally,we emphasize that the effect of storage time should be taken into account when interpreting or comparing data of plankton community acquired from samples with various storage durations.

The Relevance of Biological and Hydrodynamic Timescale in the Growth of Plankton

The relationship between hydrodynamic mesoscale structures and plankton formation in the wake of an island, as well as its interaction with a coastal upwelling, is investigated. Our focus is on the process by which vortices create localized plankton blooms. A basic three-component model for marine ecology was utilized, as well as a coupled system of kinematic flow that mimicked the mesoscale features underlying the island. We show that the prevalence of localized plankton blooms is produced mostly by the prolonged residence times of nutrients and plankton in the island’s vicinity, as well as the confinement of plankton within vortices.

Distribution characteristic and variation trend of planktonic dinoflagellate in the Taiwan Strait from 2006 to 2007

Based on 4 cruise surveys from July 2006 to October 2007 in the Taiwan Strait, the species composition, community structure and spatio-temporal distribution of dinoflagellate were studied. A total of 131 dinoflagellates belonging to 18 genera were identified. The population was dominated by hyperthermal and hyperhaline species accounting for 72.52% of the total species. Eurythermal and euryhaline species were the second most common one accounting for 25.19% of the total species. It was only 2.29% for neritic species. The maximum species number occurred in summer, while the maximum cell density appeared in spring. The average dinoflagellate cell density was 404.96x104 cells/m3. It showed that the dinof]agellate cell density increased from the nearshore waters to the open sea and from the north to the south. Compared with the results during 1984-1985, the horizontal distribution pattern and seaeonal variation of the dinofiagellate have not changed significantly, but the dinoflagellate cell density increased by 3.01 times. Further analysis of the dinoflagellate abundance variations both in the spatial and temporal aspects, indicated that the abundance of dinoflagellate increased more significantly in cold seasons, and there was a larger increase in the north of the Taiwan Strait. Besides, the dinoflagellate community structure changed notably. It showed that the diversity and evenness index were relatively high, and the proportion of dinoflageliate cell density to the total phytoplankton increased.

Evaluation of Spatial-Temporal Variations of Water Quality and Plankton Assemblages and Its Relationship to Water Use in Kulekhani Multipurpose Reservoir, Nepal

Spatial and temporal variation in planktons and water quality parameters were investigated in order to determine the effects of seasonal water use on reservoir water quality and planktons’ diversity in Kulekhani Multipurpose Reservoir, Nepal. This study also focuses on interactions among various water quality parameters with planktons and how such interactions can affect the second major utility, the fish farming in the reservoir. The analyses of seasonal water samples collected from three different sampling locations in the reservoir showed that select water quality parameters varied significantly (P < 0.05) with sampling seasons (transparency: 30 - 250 cm, pH: 7 - 7.5, alkalinity: 30 - 120 mg/L, DO: 6 - 11.5 mg/L, CO2: 0.1 - 1.1 mg/L) and sampling locations (phosphate: 0.1 - 0.25 mg/L, nitrate 0.01 - 0.19 mg/L) in the reservoir. Three groups of zooplankton and four classes of phytoplankton, respectively with eleven and twelve genera, were identified and quantified in the reservoir. Among them, Cyclops, Asplanchana, and Keratella were most dominant zooplanktons while Synedra, Melosira and Peridinum were the most dominant phytoplankton in the reservoir water. The abundance of select zooplanktons (Cyclops, Keratella, Polyanthra), and phytoplankton (Navicula, Melosira, Amphora, Chroococcus, Staurastrum, Scendesmus) showed significant interaction between sampling sites and sampling seasons, while the other varied only with sampling seasons and/or sites. These results showed that seasonal water level fluctuations, along with the variation of water quality parameters, change the abundance and diversity of planktons’ in the reservoir. Such changes can negatively impact the fish in cage culture, affecting the livelihood of people extensively relying on these fish farming.

Multivariate Analysis of Community Structure Variation of Plankton and Zoobenthos in Municipal Polluted River

[Objective] The plankton and macrobenthos samples in municipal polluted river were analyzed by different methods, so as to explore the method suitable for biological data analysis in heavy polluted area. [Method] Shannon-Wiener diversity index, cluster analysis of multivariate statistical analysis and MDS （Non-matric Multi- dimentional Scaling）analysis were used to analyze biological data of phytoplankton, zooplankton and Zoobenthos collected from the representative municipal polluted river in Pearl River Delta. The sediment samples were also collected to determine. Pb, Cd, Hg, Cr, As, Cu, Ni, Zn, as well as CODe, and NH3-N of porewater. Hakanson potential ecological risk index method was used to evaluate the ecological risk. [Re- suit] Shannon-Wiener diversity index analysis results can not effectively reflect the difference of pollution status of various stations in heavy polluted area; despite the presence of some problems, multivariate analysis method is superior to the Shannon-Wiener diversity index method in biological monitoring of heavy polluted river in the city. [Conclusion] The paper provided theoretical basis for biological data analysis in heavy polluted area.

Study on Chironomid Larvae Recognition Based on DWT and Improved KNN

A chironomid larvae images recognition method based on wavelet energy feature and improved KNN is developed. Wavelet decomposition and color information entropy are selected to construct vectors for KNN that is used to classify of the images. The distance function is modified according to the weight determined by the correlation degree between feature and class, which effectively improves classification accuracy. The result shows the mean accuracy of classification rate is up to 95.41% for freshwater plankton images, such as chironomid larvae, cyclops and harpacticoida.

Design and Testing of an Underwater Microscope with Variable Objective Lens for the Study of Benthic Communities

Monitoring the ecology and physiology of corals,sediments,planktons,and microplastic at a suitable spatial resolution is of great importance in oceanic scientific research.To meet this requirement,an underwater microscope with an electrically controlled variable lens was designed and tested.The captured microscopic images of corals,sediments,planktons,and microplastic revealed their physical,biological,and morphological characteristics.Further studies of the images also revealed the growth,degradation,and bleaching patterns of corals;the presence of plankton communities;and the types of microplastics.The imaging performance is majorly influenced by the choice of lenses,camera selection,and lighting method.Image dehazing,global saturation masks,and image histograms were used to extract the image features.Fundamental experimental proof was obtained with micro-scale images of corals,sediments,planktons,and microplastic at different magnifications.The designed underwater microscope can provide relevant new insights into the observation and detection of the future conditions of aquatic ecosystems.

Plankton community composition in the Three Gorges Reservoir Region revealed by PCR-DGGE and its relationships with environmental factors

To explore the relationships between community composition and the environment in a reservoir ecosystem, plankton communities from the Three Gorges Reservoir Region were studied by PCR-denaturing gradient gel electrophoresis fingerprinting. Bacterial and eukaryotic operational taxonomic units （OTUs）, generated by DGGE analysis of the PCR-amplified 16S and 18S rRNA genes, were used as surrogates for the dominant ＂biodiversity units＂. OTU composition among the sites was heterogeneous; 46.7% of the total bacterial OTUs （45） and 64.1% of the eukaryotic OTUs （39） were identified in less than half of the sampling sites. Unweighted pair group method with arithmetic averages （UPGMA） clustering of the OTUs suggested that the plankton communities in the Xiangxi Rive sites were not always significantly different from those from the Yangtze River sites, despite clear differences in their environmental characterizations. Canonical correspondence analysis （CCA） was applied to further investigate the relationships between OTU composition and the environmental factors. The first two CCA ordination axes suggested that the bacterial community composition was primarily correlated with the variables of NO3^--N, dissolved oxygen （DO）, and SiO3^2--Si, whereas, the eukaryotic community was mainly correlated with the concentrations of DO, PO4^3--P, and SiO3^2--Si.

Relationship between petroleum hydrocarbon and plankton in a mesocosm experiment

A mesocosm experiment was carried out from May 26 to June 1, 1998 at the location of 30'52'N, 122'36'E, the Changjiang Estuary, in order to measure the influence of petroleum hydrocar- bon to the ecosystem, furthermore, to estimate the environmental capacity. In the experiment, it is found that the petroleum hydrocarbon can, in some degree, enhance the growth of diatom, but inhibit the growth of dinoflagellate. In general, the petroleum hydrocarbon can inhibit the growth of both Phytoplankton and zooplankton, and can the inhibit the growth of total plankton (including phytoplankton and zooplankton) as well. A kinetic model was presented to estimate the uptake/release rate constants of petroleum hydrocarbon by plankton, and thereafter, the uptake and release rate constants (k1, k2), bioconcentration factor (BCF) as well as the petroleum bydrocarbon influenced influenced uptake and release rate constants of nutrients by phytoplankton (kup, krel) were obtained. The results imply that the bioconcentration of petroleum hydrocarbon by plankton is fairly large and petroleum hydrocarbon caused no significant influence on the uptake of N- NO3, but significant influence on that of P -PO4. In addition, the application of kinetic model for the bioconcentration of volatile organic toxic compound by organism suggests that the uptake of petroleum hydrocarbon by plankton was an important process for the environmental capacity of petroleum hydrocarbon.

Improved single image dehazing using dark channel prior

An improved single image dehazing method based on dark channel prior and wavelet transform is proposed. This pro-posed method employs wavelet transform and guided filter instead of the soft matting procedure to estimate and refine the depth map of haze images. Moreover, a contrast enhancement method based on just noticeable difference （JND） and quadratic function is adopted to enhance the contrast for the dehazed image, since the scene radiance is usual y not as bright as the atmospheric light, and the dehazed image looks dim. The experimental results show that the proposed approach can effectively enhance the haze ima-ge and is wel suitable for implementing on the surveil ance and obstacle detection systems.

Spatial heterogeneity in a deep artificial lake plankton community revealed by PCR-DGGE fingerprinting

To explore the spatial heterogeneity of plankton communities in a deep artificial lake （Songhua Lake, China）, samples were collected at seven sites. Samples were investigated by denaturing gradient gel electrophoresis （DGGE） analysis of the PCR-amplified 16S and 18S rRNA genes and specific bands were sequenced. Cluster analysis of the DGGE profiles revealed that all of the samples grouped into two distinct clusters, in accordance with sampling site; while in each cluster, the divergence of sub-clusters correlated with sampling depth. Sequence analysis of selected dominant DGGE bands revealed that most sequenced phylotypes （84%） exhibited 〉97% similarity to the closest sequences in GenBank, and were affiliated with ten common freshwater plankton phyla （Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Bacillariophyta, Pyrrophyta, Cryptophyta, Ciliophora, Stramenopiles, and Rotifera）. Several of these groups are also found worldwide, indicating the cosmopolitan distribution of the phylotypes. The relationships between DGGE patterns and environmental factors were analyzed by redundancy analysis （RDA）. The results suggested that, total nitrogen, nitrate, nitrite, temperature were strongly correlated with the variation ammonia, and CODMn concentrations, and water in plankton composition.

Late Cretaceous Foraminiferal Faunas from the Saiqu“mélange”in Southern Tibet

As one of the mélanges in the southern side of the Yarlung-Zangbo suture zone, the Saiqu mélange in southern Tibet is important for understanding the evolution of the Neo-Tethys ocean. The age of the Saiqu mélange, however, has been debated due to the lack of reliable fossil evidence in matrix strata. Based on lithological similarities with platform strata in southern Tibet and limited fossils from exotic blocks, previous studies variously ascribed the Saiqu mélange to be Triassic in general, Late Triassic, or Late Cretaceous. Here we reported planktonic foraminiferal faunas from the matrix strata of the Saiqu mélange. The new fossils yield a Late Cretaceous age, which is so far the best age constraint for the mélange. Regional stratigraphic correlation indicates that the Cretaceous Oceanic Red Beds （CORBs） in Saiqu may be time equivalent to the CORBs of the Zongzhuo Formation in neighboring regions. Thus the Saiqu m^lange should be correlated to the Upper Cretaceous Zongzhuo Formation rather than the Triassic Xiukang Group, as previously suggested.

Comparison of Copepod Collection Efficiencies by Three Commonly Used Plankton Nets: A Case Study in Bohai Sea, China

Abstract Selection of net with a suitable mesh size is a key concern in the quantitative assessment of zooplankton, which is cru- cial to understand pelagic ecosystem processes. This study compared the copepod collecting efficiency of three commonly used plankton nets, namely, the China standard coarse net （505 gm mesh）, the China standard fine net （77 gin）, and the WP-2 net （200 μm） The experiment was performed at six stations in the Bohai Sea during the autumn of 2012. The coarse net substantially un- der-sampled small individuals （body widths 〈 672 gm） and led to the lowest species number in each tow, whereas the fine net col- lected all small copepod species but failed to collect rare species. The WP-2 net appeared to be a compromise of the two other nets, collecting both small copepods and rare species. The abundance of copepods collected by the coarse net （126.4±86.5 indm-3） was one to two orders of magnitude lower than that by the WP-2 net （5802.4 ± 2595.4 indm3）, and the value of the fine net （11117.0±4563.41 indm-3） was nearly twice that of the WP-2 net. The abundance of large copepods （i.e., adult Calanus sinicus） in the three nets showed no significant differences, but the abundance of small copepods declined with decreasing mesh size. The dif- ference in abundance resulted from the under-sampling of small copepods with body widths 〈 672 μm and 〈 266μm by the coarse and WP-2 nets, respectively.

Paleoceanographic events of the southern Okinawa Trough during last 20 000 years

Two hteh resolution down-cores (92-255, 92-170) are used to study the Palaxeanographic events of the southern Okinawa Trough during the last 20 000 years. Planktonic foraminifera are quantitatively analyzed and three paleoceanographic events are recognized. Glacial/post-glacial variations in sea surface temperature (SST), water masses and upper water column structure are the most important environmental changes recorded by planktonic foraminifera. There is also an abrupt climatic event (about 10 710~ 9 170 a BP) during the Termination I, planktonic foraminifera (PF) δ18 O and SST have a same return pattern, but benthic foraminifera (BF) δ18 O doesn' t have.therepancy between PF δ18 O and BF δ18 O may reflect that the sea suriace water is more sensitive to abrupt, short term environmental change than the sea bottom water. High-resolution strata aIso suggest a middle- Holocene Pulleniatina obliquifoculata minimum event.

Molecular identification of scallop planktonic larvae using species-specific microsatellites

The identification of scallop larvae is essential to understand the population structure and community dynamics and to assess the potential environmental impacts caused by scallop larvae released or escaped. However, the larvae identification by morphological characteristics is notoriously difficult, mainly due to the small size （usually being less than 150 μm） and vague morphological characteristics among different scallop species. A simple and accurate molecular method was developed to identify four economically farmed scallop species, the Zhikong scallop Chlamys farreri, the noble scallop C. nobilis, the bay scallop Argopecten irradians and the Yesso scallop Mizuhopecten yessoensis. The tests used the high degree of species-specific microsatellite markers, which was specified by transferability analyses, assessed by reference individuals and evaluated by BLAST searches. The sensitivity test indicated that the species-specific microsatellites were sensitive enough for the detection of 1% -2% larvae in mixed plankton samples. Larvae collected from scallop hatcheries and their effluents and from the artificially controlled crosses were well identified to the species/hybrid level. The results demonstrated that the one-step PCR-based assay was technically simple, inexpensive and robust in identification analyses, and also less sensitive to initial quality of template DNA extracted from the ethanol-preserved samples for several years.

Difference of planktonic ciliate communities of the tropical West Pacific, the Bering Sea and the Arctic Ocean

Ciliates are important components in planktonic food webs,but our understanding of their community structures in different oceanic water masses is limited.We report pelagic ciliate community characteristics in three seas:the tropical West Pacific,the Bering Sea and the Arctic Ocean.Planktonic ciliate abundance had"bimodal-peak","surface-peak"and"DCM(deep chlorophyll a maximum layer)-peak"vertical distribution patterns in the tropical West Pacific,the Bering Sea and the Arctic Ocean,respectively.The abundance proportion of tintinnid to total ciliate in the Bering Sea(42.6%)was higher than both the tropical West Pacific(7.8%)and the Arctic Ocean(2.0%).The abundance proportion of small aloricate ciliates(10–20μm size-fraction)in the tropical West Pacific was highest in these three seas.The Arctic Ocean had higher abundance proportion of tintinnids in larger LOD(lorica oral diameter)size-class.Proportion of redundant species increased from the Arctic Ocean to the tropical West Pacific.Our result provided useful data to further understand ecology roles of planktonic ciliates in different marine habitats.