A detection method of typical toxic mixed red tide algae in Qinhuangdao based on three-dimensional fluorescence spectroscopy.

Red tides occur every year in the Qinhuangdao sea area of China, including a variety of toxic algae and non-toxic algae. Toxic red tide algae have caused great damage to the marine aquaculture industry in China and seriously endangered human health, but most of non-toxic algae are important bait for marine plankton. Therefore, it is very important to identify the type of mixed red tide algae in Qinhuangdao sea area. In this paper, three-dimensional fluorescence spectroscopy and chemometrics were applied to the identification of typical toxic mixed red tide algae in Qinhuangdao. Firstly, the three-dimensional fluorescence spectrum data of typical mixed red tide algae in Qinhuangdao sea area were measured by f-7000 fluorescence spectrometer, and the contour map of algae samples was obtained. Secondly, the contour spectrum analysis is carried out to find the excitation wavelength of the peak position of the three-dimensional fluorescence spectrum and form the new three-dimensional fluorescence spectrum data selected by the feature interval. Then, the new three-dimensional fluorescence spectrum data are extracted by principal component analysis (PCA). Finally, the feature extraction data and the data without feature extraction are used as the input of the genetic optimization support vector machine (GA-SVM) and particle swarm optimization support vector machine (PSO-SVM) classification models, respectively, to obtain the classification model of mixed red tide algae, and the two feature extraction analysis methods and two classification algorithms are compared. The results show that the classification accuracy of the test set using the principal component feature extraction and GA-SVM classification method is 92.97 %, when the excitation wavelengths are 420 nm, 440 nm, 480 nm, 500 nm and 580 nm, and the emission wavelengths are 650-750 nm. Therefore, it is feasible and effective to apply the three-dimensional fluorescence spectrum characteristics and genetic optimization support vector machine classification method to the identification of toxic mixed red tide algae in Qinhuangdao sea area.

Identification of ichthyotoxic red tide algae based on three-dimensional fluorescence spectra and particle swarm optimization support vector machine.

Acccurate identification whether red tide has ithyotoxicity is very significant for microalgae monitoring. In order to realize the rapid and non-destructive detection of ichthyotoxic red tide algae, a detection method combining three-dimensional (3D) fluorescence spectrum and particle swarm optimization support vector machine (PSO-SVM) was developed to monitor the ichthyotoxic red tide algae with cell concentrations from 104 cells/mL to 106 cells/mL. The contour maps contracted form three-dimensional fluorescence spectra of six common species of ichthyotoxic algae and eight common species of non-ichthyotoxic algae,which are analyzed to select the optimal emission and excitation wavelength span. The new feature data are acquired by using the emission spectrum data at 480 nm and 510 nm excitation wavelengths. The new feature data are used as the input of particle swarm optimization support vector machine to establish the optimal classification model of ichthyotoxic algae, which achieves an classification accuracy of 100% for the test set. The optimal classification model is successfully applied to identify the ichthyotoxicity of different algae including Heterosigma akashiwo, Chattonella marina, Phaeocystis globosa, Prorocentrum donghaiense, Karenia dunnii, Isoscelina galbana, Isosceles globosa and Skeletonema costatum.

Identification of paralytic shellfish poison producing algae based on three-dimensional fluorescence spectra and quaternion principal component analysis.

In view of the problem of the paralytic shellfish poison producing algae on-line measurement and identification, a new feature extraction method of paralytic shellfish poison producing algae measurement and identification based on quaternion principal component analysis (QPCA) is investigated. The three-dimensional (3D) fluorescence spectra of three common species of paralytic shellfish poison producing algae and eight species common of non paralytic shellfish poison producing algae are analyzed. The quaternion parallel representation model of algae three-dimensional fluorescence spectrum data is established, then the features of quaternion principal component is extracted to use as the input of k-nearest neighbor (KNN) classifier, and the identification of paralytic shellfish poison producing algae is realized by the three-dimensional fluorescence spectra coupled with quaternion principal component analysis. The results show that under the quaternion parallel representation model, the recognition accuracy rate of multiplication feature, modulus feature and summation feature is 90%, 95% and 100% respectively. Compared with that of the principal component analysis feature extraction method, the recognition accuracy rate in pure samples by summation feature of quaternion principal component is improved by 10%. This study provides an experimental basis for the accurate monitoring technology of three-dimensional fluorescence spectrum of paralytic shellfish poison producing algae.

[Identification of ichthyotoxic microalgae species and its hemolytic activity by three-dimensional fluorescence spectra].

To identify ichthyotoxic microalgae species and its hemolytic activity by three-dimensional fluorescence spectra, the relationship between hemolytic activity and the three-dimensional fluorescence of typical ichthyotoxic algae (Karenia mikimotoi, Chattonella marina, Chattonella ovata) cultured in different Fe2+ concentrations was investigated with methods of Coif2 wavelet and Fisher discriminant analysis. The results showed that the differences of three-dimensional fluorescence spectra between ichthyotoxic algae and non-ichthyotoxic algae were within the 1 to 10 data points (wavelength lambda(em) = 650-680 nm) and 35 to 47 data points (wavelength lambda(em) = 725-750 nm, lambda(ex) = 400-425 nm). Fisher discriminant analysis showed that the correct discrimination ratios of ichthyotoxic algae and non-ichthyotoxic species are 91.7% and 100%, respectively, and the ratio of algae with medium hemolytic activity (> or = 10 HU, < 20 HU) was 70% and that of algae with low hemolytic activity (< 10 HU) and high hemolytic activity (> or = 20 HU) are both of above 80%.

[Production of peroxide hydrogen in Chattonella ovata Hong Kong strain].

The growth characteristics of Chattonellea ovata Hong Kong strain (COHK) under different salinity and nutrient conditions and production of peroxide hydrogen (H2O2) in different growth phase were investigated in laboratory unialgal culture experiment. The results showed that high concentration of H2O2 was reached during the logarithmic phase from 4th to 8th days, corresponding to the maximum value of 2.91 x 10(-4) nmo x cell(-1) on the 6th day. When the N: P ratios were 16: 1, 32:1 and 64: 1, COHK possessed the relatively high growth rate and cell concentration, however, growth rate of COHK was lower with the N: P ratios of 4: 1 and 8: 1. The H2O2 concentration reached the highest (1.26 x 10(-4) nmol x cell(-1)) with the N: P ratio of 4: 1, which suggested that production of H2O2 was reversely related to the growth of COHK. The optimum salinities for COHK were 20 and 25. When the salinities were 10, 15 and 30, the growth rate of COHK was lower, showing lower and higher salinities inhibited the growth of COHK. Salinity also influenced the production of H2O2. The highest concentration of H2O2 among the experiments, 2. 2 x 10(-4) nmol x cell(-1), was observed at the salinity of 10, while there was no significant difference of H2O2 concentration from the salinity range of 15 to 30. The optimal Fe(3+) concentration for the growth of COHK was from 0.2 x 10(-8) to 1 x 10(-8) mol x L(-1), where growth rate were relatively higher. Growth rate of COHK was depressed in absence (0 mol x L(-1)) and high concentration of Fe3+ (5 x 10(-8) mol x L(-1)), with which H2O2 concentration was 0.97 x 10(-4) and 0.95 x 10(-4) nmol x cell(-1), respectively.

[Study on hemolytic activity of Chattonella marina Hong Kong strain].

Hemolytic activity of Chattonella marina Hong Kong strain (CMHK) in different growth phase and nutrients structure was studied under laboratory conditions. According to the growth curve of CMHK, cells in culture were collected in logarithmic phase, stationary phase and decline phase, respectively, to determine hemolytic activity. Hemolytic activity of CHHK, which was cultured in different nutrients structure, was also determined. Furthermore, acute toxicity test of CMHK on Artemia salina was performed in early logarithmic phase (5 d), late logarithmic phase (13 d), stationary phase (15 d) and decline phase (17 d). The results showed that the highest hemolytic activity was detected in early logarithmic phase. After 5 d culture, the hemolytic activity reached 1.80 x 10(-7) HU/cell, then decreased gradually with culture time increasing. Hemolytic activity of total cells in culture in different growth phase coincided with the growth curve with the maximum reaching 5.32 HU/L in late logarithmic phase. Growth rate of CMHK was greatly depressed by Fe limitation while hemolytic activity per cell was enhanced to 8.37 x 10(-7) HU/cell, nearly 6.5 times higher than that with no Fe limitation (1.33 x 10(-7)HU/cell). Similarly, N, Mn and P limitation could also increase the hemolytic activity of CMHK. Acute toxicity test of CMHK on A. salina showed that the maximum toxicity of the algae appeared at late logarithmic phase. It was found that death rate of A. sinica reached to 77% in 48 h when exposed to the algal culture at late logarithmic phase with algae density being 4.0 x 10(4) cells/mL, and the lowest toxicity on A. sinica appeared in early logarithmic phase with death rate of 20%.

[Population dynamics of Alexandrium tamarense and its relations with environmental factors in Nanji Islands sea area of Zhejiang Province].

Based on the investigation in Nanji Islands sea area of Zhejiang Province from April 2006 to March 2007, the dynamics of Alexandrium tamarense and its relations with environmental factors were studied. In the study sea area, A. tamarense cells could only be found in spring (from April to June), and the cell abundance was of single peak curve, with the highest (12250 cells x L(-1)) in surface water on 8th of May. Higher cell abundance of A. tamarense was found at the water temperature of 18.5 degrees C - 19.5 degrees C, salinity of 29.5 per thousand - 31.0 per thousand, and lower PO4-P concentration, but no correlation was observed between A. tamarense cell abundance and water dissolved inorganic N concentration. Linear stepwise regression revealed that there was a significant positive correlation between the cell abundance of A. tamarense and the ratio of water dissolved inorganic N to PO4-P.

Trophic transfer of paralytic shellfish toxins from the cladoceran (Moina mongolica) to larvae of the fish (Sciaenops ocellatus).

The dynamic transmission and transformation of paralytic shellfish toxins (PSTs) from the toxic dinoflagellate Alexandrium tamarense to the cladoceran Moina mongolica and subsequently to the larvae of the fish Sciaenops ocellatus were investigated under laboratory conditions. The results showed that PSTs could be transferred to S. ocellatus when they preyed on PST-containing M. mongolica. During the experimental period, A. tamarense, M. mongolica and the digestive glands of the fish larvae contained C(1/2) toxins, and the viscera of S. ocellatus contained neoSTX. The proportion of beta toxin (C2) in C(1+2) toxins increased when PSTs were transferred from A. tamarense to M. mongolica, but in the subsequent transfer from M. mongolica to S. ocellatus the proportion of alpha toxin (C1) increased. During depuration, the contents of C1 and C2 toxins in fish larvae decreased with the duration of depuration, but neoSTX remained relatively constant. The present results indicated that, using a cladoceran as the vector, PSTs can be transferred from toxic algae to a high trophic level fish and metabolized in the fish. Future work should address the metabolic characteristics of PSTs in cladocerans and the end result when they are transferred to fishes.

[Relationships between pollutants discharge and red tide occurrence in Shenzhen eastern coast].

The study on the effects of pollutants discharge on red tide occurrence in eastern sea area of Shenzhen showed that the occurrence frequency of dinoflagellate red tide had significant positive correlations with the net discharge of total nitrogen (TN) and total phosphorous (TP) as well as the N/P ratio of the discharge. The thresholds of net discharged TN and TP were estimated to be 3.917 x 10(3) t and 2.123 x 10(4) t, respectively. No significant correlation was observed between diatom red tide and alongshore pollutants discharge. An example was given to illustrate the means of pollutants discharge control.

Transfer and metabolism of paralytic shellfish poisoning from scallop (Chlamys nobilis) to spiny lobster (Panulirus stimpsoni).

The transfer and transformation of paralytic shellfish poisoning (PSP) from scallop Chlamys nobilis to spiny lobster Panulirus stimpsoni were investigated in the present study. The results demonstrate that transfer and transformation of PSP toxins occurred when Panulirus stimpsoni were fed with toxic viscera of Chlamys nobilis, but depurated with non-toxic squids. Additionally, only the lobster hepatopancreas were found to contain PSP, and the toxin profiles were the same with those in the viscera of the scallop, including carbamate toxins (GTX(1-3)), N-sulfocarbamoyl toxins (C(1+2) and B(1)) and decarbamoyl toxins (dcGTX(2+3)). Unlike the lobster, the scallop contained more alpha than beta toxins. After being fed with toxic Chlamys nobili for 6 d, Panulirus stimpsoni selectively accumulated N-sulfocarbamoyl toxins with low toxicity. However, when they were depurated with non-toxic squid, N-sulfocarbamoyl toxins tended to transform into carbamate toxins with higher toxicity. The concentration of dcGTX(2+3) in Panulirus stimpsoni decreased significantly and wasn't detectable after depuration for 6 d, which was likely due to their initial low accumulation of toxins. These results reveal that PSP could be transferred and transformed in Crustaceans along the given food chain under the conditions of laboratory, but there are many questions remained to be solved, and the further studies should be carried out.

[Analysis of paralytic shellfish poison of bivalves in seafood market in Guangzhou].

OBJECTIVE: The investigations of the paralytic shellfish poisoning (PSP) from Huangsha seafood market of Guangzhou was performed to assess the risk of PSP in bivalves. METHODS: The concentration and profiles of PSP toxins in bivalves were determined by mouse bioassay of AOAC and high-performance liquid chromatography (HPLC). The risk assessment of PSP in bivalves was conducted with FAO and Chinese Administration Organization of Fish Culture and Seaport. RESULTS: The content of PSP detected was lower than the safe standard (4 MU/g meat) in all of the 84 samples, one of which had the highest toxicity with 1.84 MU/g muscle. These results suggested that the bivalves in seafood market was safe to feed. It was 9 samples' gland in 2 species that be detected to have PSP in the bivalves being researched, the muscles had few PSP. The concentration of PSP in one sample's gland exceeded the threshold of FAO (4 MU/g) with 14.52 MU/g meat, and the profiles of PSP in the gland were B1, GTX2/3, GTX1/4 and C according to HPLC. CONCLUSION: These results suggested that both of the concentration and detection rate of PSP of bivalves in seafood market in Guangzhou were low as a whole, but the content and discovery rate of PSP were far higher in glands than in the muscles, and the PSP content in one gland exceeded the threshold of Standard. The levels of PSP contamination in shellfish was characteristic of season. The toxins level in shellfish were the maximum in spring, but the frequency of toxins detected in shellfish was higher in summer and autumn, so the detection and risk assessment of PSP in bivalves from seafood market was essential in the future.