2018 Vol. 40, No. 8
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2018, 40(8): .
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2018, 40(8): .
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2018, 40(8): 1-9.
doi: 10.3969/j.issn.0253-4193.2018.08.001
Abstract:
Information extraction of ocean mesoscale eddies includes the eddy identification and its trajectory tracking, both of which are very important for the research on mesoscale eddies based on the massive data. The traditional methods of trajectory tracking generally need to be set the threshold of the search radius beforehand, which could introduce a certain degree of subjectivity. To improve the existing problem of the traditional methods, an automatic tracking method of the mesoscale eddies is proposed in this study based on the Clustering by Fast Search and Find of Density Peaks (CFSFDP) from clustering point of view. Then it was compared with the traditional similarity algorithm by taking the South China Sea as a testbed. Our results show that:(1) Based on the CFSFDP algorithm, the automatic tracking of mesoscale eddies is realized, and the accuracy is better than the traditional similarity method; (2) The proposed tracking algorithm is less dependent on the data integrity especially for the presence of partial missing data; (3) Our proposed tracking method has stronger adaptability, which overcomes the problem that the search radius need to be set beforehand in the traditional method.
Information extraction of ocean mesoscale eddies includes the eddy identification and its trajectory tracking, both of which are very important for the research on mesoscale eddies based on the massive data. The traditional methods of trajectory tracking generally need to be set the threshold of the search radius beforehand, which could introduce a certain degree of subjectivity. To improve the existing problem of the traditional methods, an automatic tracking method of the mesoscale eddies is proposed in this study based on the Clustering by Fast Search and Find of Density Peaks (CFSFDP) from clustering point of view. Then it was compared with the traditional similarity algorithm by taking the South China Sea as a testbed. Our results show that:(1) Based on the CFSFDP algorithm, the automatic tracking of mesoscale eddies is realized, and the accuracy is better than the traditional similarity method; (2) The proposed tracking algorithm is less dependent on the data integrity especially for the presence of partial missing data; (3) Our proposed tracking method has stronger adaptability, which overcomes the problem that the search radius need to be set beforehand in the traditional method.
2018, 40(8): 10-19.
doi: 10.3969/j.issn.0253-4193.2018.08.002
Abstract:
In this paper, the clustering distribution characteristics of light falling-net fishery vessels in the northwestern part of Luzon Island (18°-22°N, 117°-120°E) were analyzed by using the Luminous remote sensing data of 2014. Moreover, the environmental mechanism was studied, combining with the remote sensing environmental data. The results showed that:(1) During 2014, the fishing lights of the study area mainly appeared in the period from February to April, specifically, the highest number of lights was in March (3 417), followed by April (1 780) and February (573); (2) The time series results of daylight number of pixels showed that the fishing light appeared from February 23 to March 8 (T1), March 25 to April 7 (T2) and April 23 to April 27 (T3). During the period of T1, the light pixel gathered at 18.6°-20.1°N, 117.9°-118.6°E (area A); as for the T2, the light pixels gathered at 18.6°-20.1°N, 117.9°-118.6°E (area B); (3) The increased of chlorophyll a concentration in the two light-intensive areas in area A and area B may be related to the cold vortex originating in northwestern Luzon Island.
In this paper, the clustering distribution characteristics of light falling-net fishery vessels in the northwestern part of Luzon Island (18°-22°N, 117°-120°E) were analyzed by using the Luminous remote sensing data of 2014. Moreover, the environmental mechanism was studied, combining with the remote sensing environmental data. The results showed that:(1) During 2014, the fishing lights of the study area mainly appeared in the period from February to April, specifically, the highest number of lights was in March (3 417), followed by April (1 780) and February (573); (2) The time series results of daylight number of pixels showed that the fishing light appeared from February 23 to March 8 (T1), March 25 to April 7 (T2) and April 23 to April 27 (T3). During the period of T1, the light pixel gathered at 18.6°-20.1°N, 117.9°-118.6°E (area A); as for the T2, the light pixels gathered at 18.6°-20.1°N, 117.9°-118.6°E (area B); (3) The increased of chlorophyll a concentration in the two light-intensive areas in area A and area B may be related to the cold vortex originating in northwestern Luzon Island.
2018, 40(8): 20-28.
doi: 10.3969/j.issn.0253-4193.2018.08.003
Abstract:
In order to evaluate the accuracy of the measurement results scientifically, uncertainty of γ-spectrum analysis of cesium-137 in seawater was studied. According to "Guidance on Evaluating the Uncertainty in Chemical Analysis", sources of the uncertainty were analyzed and quantified individually. On this basis, the combined related standard uncertainty was finally deduced. The results showed that the main causes of the uncertainty are the peak area of 137Cs sample source, the activity of standard source, the sampling volume, the chemical recovery, the area of background in 137Cs peak as well as the peak area of the 137Cs standard source, among which the contribution from the peak area of the 137Cs sample source is predominant. The combined related standard uncertainty is deduced to be 9.78% for a water sample with cesium-137 activity concentration of 1.28 mBq/L.
In order to evaluate the accuracy of the measurement results scientifically, uncertainty of γ-spectrum analysis of cesium-137 in seawater was studied. According to "Guidance on Evaluating the Uncertainty in Chemical Analysis", sources of the uncertainty were analyzed and quantified individually. On this basis, the combined related standard uncertainty was finally deduced. The results showed that the main causes of the uncertainty are the peak area of 137Cs sample source, the activity of standard source, the sampling volume, the chemical recovery, the area of background in 137Cs peak as well as the peak area of the 137Cs standard source, among which the contribution from the peak area of the 137Cs sample source is predominant. The combined related standard uncertainty is deduced to be 9.78% for a water sample with cesium-137 activity concentration of 1.28 mBq/L.
2018, 40(8): 29-41.
doi: 10.3969/j.issn.0253-4193.2018.08.004
Abstract:
The concentrations, compositions and distributions of total hydrolysable amino acids (THAAs) were investigated in the surface sediments from the Jiaozhou Bay. Combined with the TOC/TN ratios and stable carbon isotope (δ13C), carbon/nitrogen normalized yield of amino acids (THAA-C%, THAA-N%), degradation index (DI), reactivity index (RI) and D-AA% were used to indicate the origin and degradation states of organic matters in the Jiaozhou Bay sediments. Meanwhile, the contribution of bacterial to organic matters and extracellular enzyme activity (EEA) were also used to evaluate the roles of bacterial in the migration and conversion process of organic matters. The result showed that the average content of THAAs in surface sediments of the Jiaozhou Bay was (7.60±3.64) μmol/g. Under the influence of the combination of terrestrial and marine input, the concentrations of THAAs in inner bay were higher than those in outer bay, and THAAs in the eastern area of inner bay was higher than those in western areas, demonstrating the higher contribution of terrestrial input to THAAs in the eastern inner bay. According to THAA-C%, THAA-N%, DI, RI and mol% D-AA, the organic matters in sediments of inner bay were fresher than those in outer bay, and the organic matters in western inner bay area were fresher than those in the eastern area. The sources of organic matter, microbial activity and the depth of seawater column all had impacts on the degradation states of organic matter. The average bacterial contribution to organic carbon in the sediments of Jiaozhou Bay was (29.35±18.73)%, with the higher contribution in the western inner bay and outer bay. The average value of extracellular enzyme activity (EEA) of peptidase was (0.81±1.31) nmol/(g·h), and contrary to bacterial contribution to organic carbon, the EEA had the higher values in the eastern inner bay but had lower values in western inner bay and outer bay. The sources of sedimentary organic matter determined the reactivity of organic matter, and further affected the bacterial contribution to organic matter and EEA of peptidase.
The concentrations, compositions and distributions of total hydrolysable amino acids (THAAs) were investigated in the surface sediments from the Jiaozhou Bay. Combined with the TOC/TN ratios and stable carbon isotope (δ13C), carbon/nitrogen normalized yield of amino acids (THAA-C%, THAA-N%), degradation index (DI), reactivity index (RI) and D-AA% were used to indicate the origin and degradation states of organic matters in the Jiaozhou Bay sediments. Meanwhile, the contribution of bacterial to organic matters and extracellular enzyme activity (EEA) were also used to evaluate the roles of bacterial in the migration and conversion process of organic matters. The result showed that the average content of THAAs in surface sediments of the Jiaozhou Bay was (7.60±3.64) μmol/g. Under the influence of the combination of terrestrial and marine input, the concentrations of THAAs in inner bay were higher than those in outer bay, and THAAs in the eastern area of inner bay was higher than those in western areas, demonstrating the higher contribution of terrestrial input to THAAs in the eastern inner bay. According to THAA-C%, THAA-N%, DI, RI and mol% D-AA, the organic matters in sediments of inner bay were fresher than those in outer bay, and the organic matters in western inner bay area were fresher than those in the eastern area. The sources of organic matter, microbial activity and the depth of seawater column all had impacts on the degradation states of organic matter. The average bacterial contribution to organic carbon in the sediments of Jiaozhou Bay was (29.35±18.73)%, with the higher contribution in the western inner bay and outer bay. The average value of extracellular enzyme activity (EEA) of peptidase was (0.81±1.31) nmol/(g·h), and contrary to bacterial contribution to organic carbon, the EEA had the higher values in the eastern inner bay but had lower values in western inner bay and outer bay. The sources of sedimentary organic matter determined the reactivity of organic matter, and further affected the bacterial contribution to organic matter and EEA of peptidase.
2018, 40(8): 42-52.
doi: 10.3969/j.issn.0253-4193.2018.08.005
Abstract:
The ocean net primary productivity (NPP) significantly affects spatial distribution and abundance of zooplankton and phytoplankton, determining the potential catches of the marine fisheries. In this study, we evaluated the relationship between the abundance (indicated by catch per unit effort, CPUE) and distribution (indicated by longitudinal gravity center, LONG and latitudinal gravity center, LATG) of chub mackerel Scomber japonicus in the coastal waters of China and the net primary productivity by using the fishery data from July to September during 2006-2015 obtained from the data centers of Chinese distance water fishery combined with the remote sensing environmental data. The results indicated that the catch, CPUE, LONG and LATG presented clearly seasonal and interannual variability. The NPP also exhibited different spatial distribution from July to September on the fishing ground of S. japonicus. The frequency distribution analysis suggested that the suitable range of the net primary productivity for S. japonicus was 300-500 mg/(m2·d)in July, 300-400 mg/(m2·d) in August, 300-400 mg/(m2·d) in September, respectively. Correlation analysis indicated the CPUE of S. japonicus was significantly and positively correlated with the percentage of suitable range of NPP. Similarly, significant positive relationship was found between the average latitude of the suitable NPP and the LATG of S. japonicus, suggesting that the level and spatial distribution of NPP on the fishing ground of S. japonicus dramatically impacted its abundance and spatial pattern of fishing gravity centers. Negative relationship was found between the NPP and the CPUE of S. japonicus in the region 25°-30°N, 120°-130°E. Furthermore, the NPP level was different under different anomalous climate condition. The strong La Niña years in 2007 and 2010 and the moderate El Niño year in 2009 yielded reduced NPP on the fishing ground of S. japonicus, however, the suitable range of NPP for S. japonicus enlarged, leading to increased abundance of S. japonicus. Whereas the very strong El Niño in 2015 yielded relatively increased NPP on the fishing ground of S. japonicus, however, the suitable NPP area for S. japonicus significantly decreased, resulting in low abundance of S. japonicus. Our findings suggested that the S. japonicus stock in the coastal waters in China was strongly related to the net primary productivity.
The ocean net primary productivity (NPP) significantly affects spatial distribution and abundance of zooplankton and phytoplankton, determining the potential catches of the marine fisheries. In this study, we evaluated the relationship between the abundance (indicated by catch per unit effort, CPUE) and distribution (indicated by longitudinal gravity center, LONG and latitudinal gravity center, LATG) of chub mackerel Scomber japonicus in the coastal waters of China and the net primary productivity by using the fishery data from July to September during 2006-2015 obtained from the data centers of Chinese distance water fishery combined with the remote sensing environmental data. The results indicated that the catch, CPUE, LONG and LATG presented clearly seasonal and interannual variability. The NPP also exhibited different spatial distribution from July to September on the fishing ground of S. japonicus. The frequency distribution analysis suggested that the suitable range of the net primary productivity for S. japonicus was 300-500 mg/(m2·d)in July, 300-400 mg/(m2·d) in August, 300-400 mg/(m2·d) in September, respectively. Correlation analysis indicated the CPUE of S. japonicus was significantly and positively correlated with the percentage of suitable range of NPP. Similarly, significant positive relationship was found between the average latitude of the suitable NPP and the LATG of S. japonicus, suggesting that the level and spatial distribution of NPP on the fishing ground of S. japonicus dramatically impacted its abundance and spatial pattern of fishing gravity centers. Negative relationship was found between the NPP and the CPUE of S. japonicus in the region 25°-30°N, 120°-130°E. Furthermore, the NPP level was different under different anomalous climate condition. The strong La Niña years in 2007 and 2010 and the moderate El Niño year in 2009 yielded reduced NPP on the fishing ground of S. japonicus, however, the suitable range of NPP for S. japonicus enlarged, leading to increased abundance of S. japonicus. Whereas the very strong El Niño in 2015 yielded relatively increased NPP on the fishing ground of S. japonicus, however, the suitable NPP area for S. japonicus significantly decreased, resulting in low abundance of S. japonicus. Our findings suggested that the S. japonicus stock in the coastal waters in China was strongly related to the net primary productivity.
2018, 40(8): 53-62.
doi: 10.3969/j.issn.0253-4193.2018.08.006
Abstract:
The relationship between morphological attributes on body weight and morphological differentiation of Lates calcarifer was explored, 9 morphological attributes including head length (X1), stem length (X2), body length (X3), full length (X4), body height (X5), eye diameter (X6), snout length (X7), caudal peduncle height (X8), caudal peduncle length (X9) and body weight (Y) was measured from Hainan Lingshui land-based culture and Nansha Meiji Reef offshore sea cage culture population of fifteen month old Lates calcarifer by correlation analysis, path analysis and regression analysis. The results showed that there were no significant differences in the eye diameter and snout length in the two breeding conditions, but in the body weight, head length, stem length, body length, full length, body height, caudal peduncle height, caudal peduncle length and the ratio of body height and full length was very significant difference (P<0.01). There were significant correlations or highly significant correlations (P<0.01 or P<0.05) among the 9 morphological attributes and body weight in land-based culture population, and similar results in Meiji reef's offshore sea cage culture population in addition to X6 and X7 have no significant correlation. The path analysis revealed that the direct effects of X4 and X5 on body weight were significant (P<0.01) in land-based culture population, and the direct effects of X3, X5 and X9 on body weight were significant or highly significant (P<0.01 or P<0.05) in Meiji reef's offshore sea cage culture population. The analysis results of determination coefficients showed that the total decision coefficient of morphological attributes to body weight is find to be 0.971 and 0.864 respectively, and indicating the morphological attributes are the main factor to body weight. The multiple regression equation was expressed as Y=-1 128.61+3.143 X4+6.418 X5, Y=-2 054.81+7.377 X3+9.196 X5-10.041 X9 are established by stepwise regression analysis respectively. The findings indicate that there are significant differences in the 2 rearing model of L. calcarifer, and Meiji reef's offshore sea cage aquaculture advantage the body shape of L. calcarifer.
The relationship between morphological attributes on body weight and morphological differentiation of Lates calcarifer was explored, 9 morphological attributes including head length (X1), stem length (X2), body length (X3), full length (X4), body height (X5), eye diameter (X6), snout length (X7), caudal peduncle height (X8), caudal peduncle length (X9) and body weight (Y) was measured from Hainan Lingshui land-based culture and Nansha Meiji Reef offshore sea cage culture population of fifteen month old Lates calcarifer by correlation analysis, path analysis and regression analysis. The results showed that there were no significant differences in the eye diameter and snout length in the two breeding conditions, but in the body weight, head length, stem length, body length, full length, body height, caudal peduncle height, caudal peduncle length and the ratio of body height and full length was very significant difference (P<0.01). There were significant correlations or highly significant correlations (P<0.01 or P<0.05) among the 9 morphological attributes and body weight in land-based culture population, and similar results in Meiji reef's offshore sea cage culture population in addition to X6 and X7 have no significant correlation. The path analysis revealed that the direct effects of X4 and X5 on body weight were significant (P<0.01) in land-based culture population, and the direct effects of X3, X5 and X9 on body weight were significant or highly significant (P<0.01 or P<0.05) in Meiji reef's offshore sea cage culture population. The analysis results of determination coefficients showed that the total decision coefficient of morphological attributes to body weight is find to be 0.971 and 0.864 respectively, and indicating the morphological attributes are the main factor to body weight. The multiple regression equation was expressed as Y=-1 128.61+3.143 X4+6.418 X5, Y=-2 054.81+7.377 X3+9.196 X5-10.041 X9 are established by stepwise regression analysis respectively. The findings indicate that there are significant differences in the 2 rearing model of L. calcarifer, and Meiji reef's offshore sea cage aquaculture advantage the body shape of L. calcarifer.
2018, 40(8): 63-78.
doi: 10.3969/j.issn.0253-4193.2018.08.007
Abstract:
The variation of sediment erosion and deposition in salt marsh is one of the important factors that affect the composition and distribution of the benthic macroinvertebrate functional groups. During dry season the Nanhui Dongtan in the Changjiang River Estuary was selected as the study area, with a fixed sample sites. On November 2015 and February 2016, respectively, benthic macroinvertebrates, sediment physical-chemical factors were surveyed seasonally and erosion-deposition characteristics were observed monthly during the period. The effects of sediment erosion and deposition variation on the functional groups and corresponding mechanisms were analyzed based on these. A total of 37 species of the benthic macroinvertebrates were recorded during the surveys. Among them, 25 species were omnivores, 7 species were herbivores and only 5 species happened to be carnivores. These three different feeding habit functional groups appeared to have different spatial-temporal variation characteristics in number of species, density and biomass. Between the seasonal surveys, the number of species of the three different functional groups were all slightly decreased, and the density of the herbivore was significantly increased (P<0.01),while the density of the carnivore and omnivore appeared to have no significant changes (P>0.05).The biomass of the three functional groups did not change significantly (P>0.05).Both the density and biomass of the herbivore showed extremely significant differences among the sampling sites (P<0.01), while the carnivore and omnivore only showed such kind of significant difference in density in February 2016 (P<0.05). Monthly variation characteristics of sediment erosion and deposition appeared to be different in the different sites, but all sites tended to be silted. Most of the environmental factors had significant spatial difference (P<0.05),except the median grain size of the sediments in the different depths. Sediment erosion and deposition appeared to lead the variations of the physical-chemical factors of the sediments. It was varied that the combinations of selected environmental factors which were significantly correlated with the number of species, density and biomass varied with groups. The absolute amount of sediment erosion and deposition appeared in the combinations of environmental factors which were significantly correlated with the variations of the density and biomass of the herbivores and number of species of the carnivores. In addition to the direct effect on the macrobenthos, the variation of the sediment erosion and deposition will also indirectly affect on the macrozoobenthos by changing the characteristics of sedimentary physicochemical factors. The main factors which had effects on the different feeding-habit functional groups appeared to be different. Although the species number of feeding habit functional groups decreased, the nutrient environment in sediment was more favorable to the survival of omnivores than the other two functional groups. Therefore, omnivores have an advantage in the competitive process. Further comprehensive studies should be carried out based on the systematic monitoring and the combination with the observation results of flood season.
The variation of sediment erosion and deposition in salt marsh is one of the important factors that affect the composition and distribution of the benthic macroinvertebrate functional groups. During dry season the Nanhui Dongtan in the Changjiang River Estuary was selected as the study area, with a fixed sample sites. On November 2015 and February 2016, respectively, benthic macroinvertebrates, sediment physical-chemical factors were surveyed seasonally and erosion-deposition characteristics were observed monthly during the period. The effects of sediment erosion and deposition variation on the functional groups and corresponding mechanisms were analyzed based on these. A total of 37 species of the benthic macroinvertebrates were recorded during the surveys. Among them, 25 species were omnivores, 7 species were herbivores and only 5 species happened to be carnivores. These three different feeding habit functional groups appeared to have different spatial-temporal variation characteristics in number of species, density and biomass. Between the seasonal surveys, the number of species of the three different functional groups were all slightly decreased, and the density of the herbivore was significantly increased (P<0.01),while the density of the carnivore and omnivore appeared to have no significant changes (P>0.05).The biomass of the three functional groups did not change significantly (P>0.05).Both the density and biomass of the herbivore showed extremely significant differences among the sampling sites (P<0.01), while the carnivore and omnivore only showed such kind of significant difference in density in February 2016 (P<0.05). Monthly variation characteristics of sediment erosion and deposition appeared to be different in the different sites, but all sites tended to be silted. Most of the environmental factors had significant spatial difference (P<0.05),except the median grain size of the sediments in the different depths. Sediment erosion and deposition appeared to lead the variations of the physical-chemical factors of the sediments. It was varied that the combinations of selected environmental factors which were significantly correlated with the number of species, density and biomass varied with groups. The absolute amount of sediment erosion and deposition appeared in the combinations of environmental factors which were significantly correlated with the variations of the density and biomass of the herbivores and number of species of the carnivores. In addition to the direct effect on the macrobenthos, the variation of the sediment erosion and deposition will also indirectly affect on the macrozoobenthos by changing the characteristics of sedimentary physicochemical factors. The main factors which had effects on the different feeding-habit functional groups appeared to be different. Although the species number of feeding habit functional groups decreased, the nutrient environment in sediment was more favorable to the survival of omnivores than the other two functional groups. Therefore, omnivores have an advantage in the competitive process. Further comprehensive studies should be carried out based on the systematic monitoring and the combination with the observation results of flood season.
2018, 40(8): 79-88.
doi: 10.3969/j.issn.0253-4193.2018.08.008
Abstract:
Chaetoceros muelleri, Platymonas subcordiformis and Isochrysis galbana were chosen as a representative of diatom, chlorophyta and chrysophyta for the food of Crassostrea hongkongensis, and the clearance rate, filtration rate and selection efficiency of different size Crassostrea hongkongensis feeding on these three algae were examined on the same density and biomass, to study the feeding selectivity of Crassostrea hongkongensis. The results showed that there were significant differences among the feeding selection efficiency of C. hongkongens is on the three algae in the condition of same density as well as same biomass. Selection efficiency of large-size, medium-size and small-size of the C. hongkongens on Platymonas subcordiformis were 0.32,0.35,0.48 under the circumstance of same density, respectively. C. hongkongensis had higher feeding selectivity on the large size algae than small size algae. C. hongkongensis showed feeding selectivity on Isochrysis galbana and Platymonas subcordiformis under the same biomass of algae. However, C. hongkongensis feeding on Chaetoceros muelleri showed negative selection efficiency both under the same density and biomass mixed conditions. The smaller size of the C. hongkongensis showed the higher feeding selectivity on the studied algae. And the size, shape and nutritive value of microalgae and the size of C. hongkongensis had obvious effects on the feeding selectivity of the C. hongkongensis.
Chaetoceros muelleri, Platymonas subcordiformis and Isochrysis galbana were chosen as a representative of diatom, chlorophyta and chrysophyta for the food of Crassostrea hongkongensis, and the clearance rate, filtration rate and selection efficiency of different size Crassostrea hongkongensis feeding on these three algae were examined on the same density and biomass, to study the feeding selectivity of Crassostrea hongkongensis. The results showed that there were significant differences among the feeding selection efficiency of C. hongkongens is on the three algae in the condition of same density as well as same biomass. Selection efficiency of large-size, medium-size and small-size of the C. hongkongens on Platymonas subcordiformis were 0.32,0.35,0.48 under the circumstance of same density, respectively. C. hongkongensis had higher feeding selectivity on the large size algae than small size algae. C. hongkongensis showed feeding selectivity on Isochrysis galbana and Platymonas subcordiformis under the same biomass of algae. However, C. hongkongensis feeding on Chaetoceros muelleri showed negative selection efficiency both under the same density and biomass mixed conditions. The smaller size of the C. hongkongensis showed the higher feeding selectivity on the studied algae. And the size, shape and nutritive value of microalgae and the size of C. hongkongensis had obvious effects on the feeding selectivity of the C. hongkongensis.
2018, 40(8): 89-96.
doi: 10.3969/j.issn.0253-4193.2018.08.009
Abstract:
In 2012-2013, mangrove sediment samples were collected from four stations in Jiulong River Estuary in Longhai City and Luoyang River Estuary in Quanzhou City. The individual dry weight of marine nematodes was analyzed in four seasons. Based on size measurements of the dominant nematode genera, the individual dry weight ranged from 0.14 to 4.88 μg for adults, from 0.17 to 1.87 μg for juveniles, with an average of 0.826 μg per individual. The analysis showed that the proportion of the juvenile nematodes in different seasons and the species composition were the main factors affecting the estimation of the individual biomass of marine nematodes. For better estimation of nematode biomass, it is suggested to calculate by direct measurement, while simple estimation by using 0.8 μg/ind. is practical for the estimation of nematode biomass in mangrove sediments.
In 2012-2013, mangrove sediment samples were collected from four stations in Jiulong River Estuary in Longhai City and Luoyang River Estuary in Quanzhou City. The individual dry weight of marine nematodes was analyzed in four seasons. Based on size measurements of the dominant nematode genera, the individual dry weight ranged from 0.14 to 4.88 μg for adults, from 0.17 to 1.87 μg for juveniles, with an average of 0.826 μg per individual. The analysis showed that the proportion of the juvenile nematodes in different seasons and the species composition were the main factors affecting the estimation of the individual biomass of marine nematodes. For better estimation of nematode biomass, it is suggested to calculate by direct measurement, while simple estimation by using 0.8 μg/ind. is practical for the estimation of nematode biomass in mangrove sediments.
2018, 40(8): 97-109.
doi: 10.3969/j.issn.0253-4193.2018.08.010
Abstract:
According to monitoring data of coral reefs from 2007 to 2016, there are 11 families and 113 species of hermatypic corals in Yongxing Islands and Qilianyu Islands, in which Pocillopora damicornis, P. verrucosa, Acropora humilis, Porites lutea, Galaxea fascicularis, Goniastrea pectinata and Cyphastrea serailia were common species. In nearly a decade (2007-2016), species number of hermatypic corals significantly declined in survey area, and 53.85% reduction in species number from 39 to 19 was recorded in Yongxing Island, 26.09% reduction from 23 to 17 in Bei Island, 73.91% reduction from 46 to 12 in Zhaoshu Island, and 70.59% reduction from 51 to 19 in Xishazhou Island. Analysis showed that the crusting hermatypic corals were stable in species number in nearly a decade, but other type of hermatypic corals showed a sharp decrease, 59.26% for branching corals, 75.0% for those with thin plate, 87.50% for free-living Fungiidae corals and 57.14% for massive corals. The coral ecosystem in the Xisha Sea was gradually affected by anthropogenic activities, outbreak of crown-of-thorns starfish, coral disease, typhoons and global warming, based on the analysis of the changes of coral species composition and community forms in the study area.
According to monitoring data of coral reefs from 2007 to 2016, there are 11 families and 113 species of hermatypic corals in Yongxing Islands and Qilianyu Islands, in which Pocillopora damicornis, P. verrucosa, Acropora humilis, Porites lutea, Galaxea fascicularis, Goniastrea pectinata and Cyphastrea serailia were common species. In nearly a decade (2007-2016), species number of hermatypic corals significantly declined in survey area, and 53.85% reduction in species number from 39 to 19 was recorded in Yongxing Island, 26.09% reduction from 23 to 17 in Bei Island, 73.91% reduction from 46 to 12 in Zhaoshu Island, and 70.59% reduction from 51 to 19 in Xishazhou Island. Analysis showed that the crusting hermatypic corals were stable in species number in nearly a decade, but other type of hermatypic corals showed a sharp decrease, 59.26% for branching corals, 75.0% for those with thin plate, 87.50% for free-living Fungiidae corals and 57.14% for massive corals. The coral ecosystem in the Xisha Sea was gradually affected by anthropogenic activities, outbreak of crown-of-thorns starfish, coral disease, typhoons and global warming, based on the analysis of the changes of coral species composition and community forms in the study area.
2018, 40(8): 110-119.
doi: 10.3969/j.issn.0253-4193.2018.08.011
Abstract:
Marine transparent exopolymer particles (TEP) is the core component in marine aggregation web. It is very important for gradient structure of water environment in microscale, which plays an important role in the marine food web and biogeochemical cycle, especially on the carbon sinking processes. This article firstly reports the TEP resources and its seasonal distribution along PN section in the East China Sea. Our results show that the concentration of TEP is between 28 and 376 μg Xeq./L, and the mean value was (115±67) μg Xeq./L in the East China Sea. The seasonal change of TEP is abundant in turn of in summer, winter, autumn and spring, and in surface layer is greater than bottom layer, in near shore is abundant than in open ocean. According to the distribution patterns of TEP, the diatoms and dinoflagellates, it can be concluded that the main sources of TEP in PN section of the East China Sea were mainly come from the diatoms, and in the open ocean, the TEP is major from the picophytoplankton.
Marine transparent exopolymer particles (TEP) is the core component in marine aggregation web. It is very important for gradient structure of water environment in microscale, which plays an important role in the marine food web and biogeochemical cycle, especially on the carbon sinking processes. This article firstly reports the TEP resources and its seasonal distribution along PN section in the East China Sea. Our results show that the concentration of TEP is between 28 and 376 μg Xeq./L, and the mean value was (115±67) μg Xeq./L in the East China Sea. The seasonal change of TEP is abundant in turn of in summer, winter, autumn and spring, and in surface layer is greater than bottom layer, in near shore is abundant than in open ocean. According to the distribution patterns of TEP, the diatoms and dinoflagellates, it can be concluded that the main sources of TEP in PN section of the East China Sea were mainly come from the diatoms, and in the open ocean, the TEP is major from the picophytoplankton.
2018, 40(8): 120-128.
doi: 10.3969/j.issn.0253-4193.2018.08.012
Abstract:
In order to explore the feeding characteristics of Sphaeroma retrolaeve, we analyzed the carbon and nitrogen isotopic ratios (δ13C values, δ15N values) of S. retrolaeve and its food sources which were collected from the mangrove of Lianzhou Bay, Beihai, Guangxi, in the winter of 2015 and summer of 2016, based on the stable carbon and nitrogen isotope analysis. The results showed that the average δ13C and δ15N values of S. retrolaeve were (-22.46±0.35) ‰ and (11.88±0.56)‰, in a range of -22.85‰ to -21.87‰ and 11.02‰ to 12.85‰, respectively. The range of δ13C value and the δ15N value of S. retrolaeve was small, which indicated that the food sources of S. retrolaeve were relatively simple. The results of one-way ANOVA showed that the δ13C values of S. retrolaeve were insignificantly different between winter and summer (P>0.05), while the δ15N values in summer were generally higher than those in winter, and the difference was significant (P<0.05); δ13C and δ15N values of S. retrolaeve of different growth stages significantly correlated with body size (P<0.05), which indicated that its feeding habits shift during its growth process. The δ13C values of S. retrolaeve were similar to the δ13C values of the plankton, which were far different from the δ13C values of the mangrove plants, indicating that the main food sources of S. retrolaeve was plankton. The results of SIAR mixing model analysis showed that contribution rates of plankton to different growth stages of S.retrolaeve were basically the same in winter and summer. The plankton with the fraction of 1.2-25 μm had the highest contribution to S. retrolaeve, and followed by the fraction of 25-50 μm, the fraction more than 100 μm had a lower contribution to S. retrolaeve with body length less than 5.5 mm, while the proportion of contribution would increase with increasing body length, which showed that there were something differences in the feeding habits for S. retrolaeve at different growth stages. The results of the feeding habits of S. retrolaeve could provide basic information for further studying the causes of Sphaeroma outbreak and the mechanism of damage to mangroves.
In order to explore the feeding characteristics of Sphaeroma retrolaeve, we analyzed the carbon and nitrogen isotopic ratios (δ13C values, δ15N values) of S. retrolaeve and its food sources which were collected from the mangrove of Lianzhou Bay, Beihai, Guangxi, in the winter of 2015 and summer of 2016, based on the stable carbon and nitrogen isotope analysis. The results showed that the average δ13C and δ15N values of S. retrolaeve were (-22.46±0.35) ‰ and (11.88±0.56)‰, in a range of -22.85‰ to -21.87‰ and 11.02‰ to 12.85‰, respectively. The range of δ13C value and the δ15N value of S. retrolaeve was small, which indicated that the food sources of S. retrolaeve were relatively simple. The results of one-way ANOVA showed that the δ13C values of S. retrolaeve were insignificantly different between winter and summer (P>0.05), while the δ15N values in summer were generally higher than those in winter, and the difference was significant (P<0.05); δ13C and δ15N values of S. retrolaeve of different growth stages significantly correlated with body size (P<0.05), which indicated that its feeding habits shift during its growth process. The δ13C values of S. retrolaeve were similar to the δ13C values of the plankton, which were far different from the δ13C values of the mangrove plants, indicating that the main food sources of S. retrolaeve was plankton. The results of SIAR mixing model analysis showed that contribution rates of plankton to different growth stages of S.retrolaeve were basically the same in winter and summer. The plankton with the fraction of 1.2-25 μm had the highest contribution to S. retrolaeve, and followed by the fraction of 25-50 μm, the fraction more than 100 μm had a lower contribution to S. retrolaeve with body length less than 5.5 mm, while the proportion of contribution would increase with increasing body length, which showed that there were something differences in the feeding habits for S. retrolaeve at different growth stages. The results of the feeding habits of S. retrolaeve could provide basic information for further studying the causes of Sphaeroma outbreak and the mechanism of damage to mangroves.
2018, 40(8): 129-137.
doi: 10.3969/j.issn.0253-4193.2018.08.013
Abstract:
Total antioxidant capacity (TAC), DPPH radical scavenging activity (DPPH), ferrous ion-chelating activity (FICA), reducing power (RP) were measured to evaluate the antioxidant capacity of different polarity fractions of alcohol aqueous extracts of Crypthecodinium cohnii residue, aiming to provide theoretical reference value for comprehensively utilizing C. cohnii. Folin-Ciocalteu and spectrophotometry method was used to determine total phenolic content (TPC) and total flavonoid content (TFC). The results showed that different polar fractions of the residue of C.cohnii had certain antioxidant capacity with a mass concentration-depended effect. The fraction of ethyl acetate and petroleum ether showed higher TAC and FICA than that of water and n-butanol, which showed higher DPPH and RP. Correlation analysis indicated that TPC was positively correlated with DPPH and RP, while TFC was positively with TAC and FICA. The residue of C. cohnii exhibits good antioxidant activity, while its effective active ingredients need to be further studied.
Total antioxidant capacity (TAC), DPPH radical scavenging activity (DPPH), ferrous ion-chelating activity (FICA), reducing power (RP) were measured to evaluate the antioxidant capacity of different polarity fractions of alcohol aqueous extracts of Crypthecodinium cohnii residue, aiming to provide theoretical reference value for comprehensively utilizing C. cohnii. Folin-Ciocalteu and spectrophotometry method was used to determine total phenolic content (TPC) and total flavonoid content (TFC). The results showed that different polar fractions of the residue of C.cohnii had certain antioxidant capacity with a mass concentration-depended effect. The fraction of ethyl acetate and petroleum ether showed higher TAC and FICA than that of water and n-butanol, which showed higher DPPH and RP. Correlation analysis indicated that TPC was positively correlated with DPPH and RP, while TFC was positively with TAC and FICA. The residue of C. cohnii exhibits good antioxidant activity, while its effective active ingredients need to be further studied.
2018, 40(8): 138-151.
doi: 10.3969/j.issn.0253-4193.2018.08.014
Abstract:
Distribution of culturable bacteria in the Guangxi Shankou mangrove rhizosphere sediments was investigated in this study. 25 sediment samples collected from Guangxi mangrove rhizosphere sediments were used for bacterial diversity research by using the culture dependent method. 117 isolates were selected for further study. Phylogenetic analysis based on the partial 16S rRNA sequences clustered the 117 isolates into 9 classes, 20 orders, 27 families and 35 genera. 9 classes include Alphaproteobacteria(21.37%), Betaproteobacteria(1.71%), Gammaproteobacteria(12.82%), Deltabacteria(0.85%), Cytophagia(0.85%), Sphingobacteria (0.85%), Flavobacteria(2.56%), Actinobacteria(27.35%) and Bacilli(31.62%). The dominant genus was Bacillus, in which takes a great proportion of 28.20%. Additionally, 7 potential novel species from Alphaproteobacteria, Gammaproteobacteria, Flavobacteria and Actinobacteria were obtained. The results showed that bacteria producing amylase, protease, glucanase, cellulase and chitinase were abundant in the rhizosphere sediments of Shankou mangrove. Bacilli produced the most multiple enzymes. The preliminary study indicates that population diversity of culturable bacteria was abundant in the Guangxi Shankou mangrove rhizosphere sediments, and this worth further studies.
Distribution of culturable bacteria in the Guangxi Shankou mangrove rhizosphere sediments was investigated in this study. 25 sediment samples collected from Guangxi mangrove rhizosphere sediments were used for bacterial diversity research by using the culture dependent method. 117 isolates were selected for further study. Phylogenetic analysis based on the partial 16S rRNA sequences clustered the 117 isolates into 9 classes, 20 orders, 27 families and 35 genera. 9 classes include Alphaproteobacteria(21.37%), Betaproteobacteria(1.71%), Gammaproteobacteria(12.82%), Deltabacteria(0.85%), Cytophagia(0.85%), Sphingobacteria (0.85%), Flavobacteria(2.56%), Actinobacteria(27.35%) and Bacilli(31.62%). The dominant genus was Bacillus, in which takes a great proportion of 28.20%. Additionally, 7 potential novel species from Alphaproteobacteria, Gammaproteobacteria, Flavobacteria and Actinobacteria were obtained. The results showed that bacteria producing amylase, protease, glucanase, cellulase and chitinase were abundant in the rhizosphere sediments of Shankou mangrove. Bacilli produced the most multiple enzymes. The preliminary study indicates that population diversity of culturable bacteria was abundant in the Guangxi Shankou mangrove rhizosphere sediments, and this worth further studies.
2018, 40(8): 152-164.
doi: 10.3969/j.issn.0253-4193.2018.08.015
Abstract:
To explore the cultivable microbial diversity in the Ross Sea region of Antarctica and take advantage of Antarctic recourses, we isolated bacteria and fungi from the samples of 6 stations in Ross Sea during the 33th China Antarctic scientific expedition. 16S rRNA and fungal ITS analysis suggest that a total of 36 strains of bacteria are from 5 genera and 29 fungi are from 6 genera. Among them, the Psychrobacter is the dominant bacteria, Cladosporium is the dominant fungi. The results show that the microorganisms in the sediments of Ross Sea are rich in diversity. 20 NE API test and fungi extracellular enzyme activity test showed that most of the isolated bacteria and fungi can produce different low-temperature enzymes. The results provide support for the diversity of culturable microorganisms in the Ross Sea area of Antarctica and the acquisition and development of low-temperature enzyme-producing bacteria.
To explore the cultivable microbial diversity in the Ross Sea region of Antarctica and take advantage of Antarctic recourses, we isolated bacteria and fungi from the samples of 6 stations in Ross Sea during the 33th China Antarctic scientific expedition. 16S rRNA and fungal ITS analysis suggest that a total of 36 strains of bacteria are from 5 genera and 29 fungi are from 6 genera. Among them, the Psychrobacter is the dominant bacteria, Cladosporium is the dominant fungi. The results show that the microorganisms in the sediments of Ross Sea are rich in diversity. 20 NE API test and fungi extracellular enzyme activity test showed that most of the isolated bacteria and fungi can produce different low-temperature enzymes. The results provide support for the diversity of culturable microorganisms in the Ross Sea area of Antarctica and the acquisition and development of low-temperature enzyme-producing bacteria.
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