2016 Vol. 35, No. 4
Display Method:
2016, 35(4): .
Abstract:
2016, 35(4): .
Abstract:
Evaluation of diagnostic ratios of medium and serious weathered oils from five different oil sources
2016, 35(4): 1-8.
doi: 10.1007/s13131-015-0721-9
Abstract:
Laboratory experiments were conducted to simulate oil weathering process, a medium to long term weathering process for 210-d, using samples collected from five different oil resources. Based on relative deviation and repeatability limit analysis about indexes of these samples, the results show there had been significant changes in diagnostic ratios among the initial and weathered samples of different oils during this process. Changes of selected n-alkane diagnostic ratios of all oil samples displayed more obviously than diagnostic ratios of terpanes, steranes and PAHs in this process. Almost all selected diagnostic ratios of terpanes, steranes and PAHs can be efficiently used in tracking sources of hydrocarbon pollution, differentiating from the n-alkane diagnostic ratios. In these efficient diagnostic ratios, only four ratios maintained good stability in the weathering processes and are more suitable because their relative deviation(RSD) are lower than 5%.
Laboratory experiments were conducted to simulate oil weathering process, a medium to long term weathering process for 210-d, using samples collected from five different oil resources. Based on relative deviation and repeatability limit analysis about indexes of these samples, the results show there had been significant changes in diagnostic ratios among the initial and weathered samples of different oils during this process. Changes of selected n-alkane diagnostic ratios of all oil samples displayed more obviously than diagnostic ratios of terpanes, steranes and PAHs in this process. Almost all selected diagnostic ratios of terpanes, steranes and PAHs can be efficiently used in tracking sources of hydrocarbon pollution, differentiating from the n-alkane diagnostic ratios. In these efficient diagnostic ratios, only four ratios maintained good stability in the weathering processes and are more suitable because their relative deviation(RSD) are lower than 5%.
2016, 35(4): 9-18.
doi: 10.1007/s13131-016-0840-y
Abstract:
Sediment distribution is important for morphodynamic evolution and shoreline changes in coastal zones and estuaries. In the study, the data of 230 surface sediment samples collected from the Xiamen Bay sea area in September 2008 are used to investigate the spatial distribution and sediment transport pathway. The grain size distribution of surficial sediments in the Xiamen Bay area is shown distinctly in this study. In addition, the Grain Size Transport Analysis model is used for conveying trend analysis of the sediment in this area, particularly for determining the sediment movement trend. The results indicate that eight sediment types are present for samples, with clayey silt comprising the highest percentage in the study area at 65.22%. Moreover, in the different subareas, the characteristics of grain size parameters are obviously different owing to different sediment sources and hydrodynamic conditions. Furthermore, runoff, tides, and waves are the main forces dominating sediment dynamics on the seabed and tidal flats, and the sediment movement trend is closely related to hydrodynamic conditions.
Sediment distribution is important for morphodynamic evolution and shoreline changes in coastal zones and estuaries. In the study, the data of 230 surface sediment samples collected from the Xiamen Bay sea area in September 2008 are used to investigate the spatial distribution and sediment transport pathway. The grain size distribution of surficial sediments in the Xiamen Bay area is shown distinctly in this study. In addition, the Grain Size Transport Analysis model is used for conveying trend analysis of the sediment in this area, particularly for determining the sediment movement trend. The results indicate that eight sediment types are present for samples, with clayey silt comprising the highest percentage in the study area at 65.22%. Moreover, in the different subareas, the characteristics of grain size parameters are obviously different owing to different sediment sources and hydrodynamic conditions. Furthermore, runoff, tides, and waves are the main forces dominating sediment dynamics on the seabed and tidal flats, and the sediment movement trend is closely related to hydrodynamic conditions.
2016, 35(4): 19-25.
doi: 10.1007/s13131-016-0839-4
Abstract:
The geological evolution of the Earth during the mid-Cretaceous were shown to be anomalous, e.g., the pause of the geomagnetic field, the global sea level rise, and increased intra-plate volcanic activities, which could be attributed to deep mantle processes. As the anomalous volcanic activities occurred mainly in the Cretaceous Pacific, here we use basalt chemical compositions from the oceanic drilling(DSDP/ODP/IODP) sites to investigate their mantle sources and melting conditions. Based on locations relative to the Pacific plateaus, we classified these sites as oceanic plateau basalts, normal mid-ocean ridge basalts, and near-plateau seafloor basalts. This study shows that those normal mid-ocean ridge basalts formed during mid-Cretaceous are broadly similar in average Na8, La/Sm and Sm/Yb ratios and Sr-Nd isotopic compositions to modern Pacific spreading ridge(the East Pacific Rise). The Ontong Java plateau(125-90 Ma) basalts have distinctly lower Na8 and 143Nd/144Nd, and higher La/Sm and 87Sr/86Sr than normal seafloor basalts, whereas those for the near-plateau seafloor basalts are similar to the plateau basalts, indicating influences from the Ontong Java mantle source. The super mantle plume activity that might have formed the Ontong Java plateau influenced the mantle source of the simultaneously formed large areas of seafloor basalts. Based on the chemical data from normal seafloor basalts, I propose that the mantle compositions and melting conditions of the normal mid-ocean ridges during the Cretaceous are similar to the fast spreading East Pacific Rise. Slight variations of mid-Cretaceous normal seafloor basalts in melting conditions could be related to the local mantle source and spreading rate.
The geological evolution of the Earth during the mid-Cretaceous were shown to be anomalous, e.g., the pause of the geomagnetic field, the global sea level rise, and increased intra-plate volcanic activities, which could be attributed to deep mantle processes. As the anomalous volcanic activities occurred mainly in the Cretaceous Pacific, here we use basalt chemical compositions from the oceanic drilling(DSDP/ODP/IODP) sites to investigate their mantle sources and melting conditions. Based on locations relative to the Pacific plateaus, we classified these sites as oceanic plateau basalts, normal mid-ocean ridge basalts, and near-plateau seafloor basalts. This study shows that those normal mid-ocean ridge basalts formed during mid-Cretaceous are broadly similar in average Na8, La/Sm and Sm/Yb ratios and Sr-Nd isotopic compositions to modern Pacific spreading ridge(the East Pacific Rise). The Ontong Java plateau(125-90 Ma) basalts have distinctly lower Na8 and 143Nd/144Nd, and higher La/Sm and 87Sr/86Sr than normal seafloor basalts, whereas those for the near-plateau seafloor basalts are similar to the plateau basalts, indicating influences from the Ontong Java mantle source. The super mantle plume activity that might have formed the Ontong Java plateau influenced the mantle source of the simultaneously formed large areas of seafloor basalts. Based on the chemical data from normal seafloor basalts, I propose that the mantle compositions and melting conditions of the normal mid-ocean ridges during the Cretaceous are similar to the fast spreading East Pacific Rise. Slight variations of mid-Cretaceous normal seafloor basalts in melting conditions could be related to the local mantle source and spreading rate.
2016, 35(4): 26-34.
doi: 10.1007/s13131-016-0831-z
Abstract:
The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt marsh. Since the exotic species Spartina alterniflora(S. alterniflora) was introduced in 1995, a rapid expansion has occurred at Chongming Dongtan Nature Reserve(CDNR) in the Changjiang(Yangtze) River Estuary, China. Several important vegetation-environment factors including soil elevation, tidal channels density(TCD), vegetation classification and fractional vegetation cover(FVC) were extracted by remote sensing method combined with field measurement. To ignore the details in interaction between biological and physical process, the relationship between them was discussed at a large scale of the whole saltmarsh. The results showed that Scirpus mariqueter(S. mariqueter) can endure the greatest elevation variance with 0.33 m throughout the marsh in CDNR. But it is dominant in the area less than 2.5 m with the occurrence frequency reaching 98%. S. alterniflora has usually been found on the most elevated soils higher than 3.5 m but has a narrow spatial distribution. The rapid decrease of S. mariqueter can be explained by stronger competitive capacity of S. alterniflora on the high tidal flat. FVC increases with elevation which shows significant correlation with elevation(r=0.30, p<0.001). But the frequency distribution of FVC indicates that vegetation is not well developed on both elevated banks near tidal channels from the whole scale mainly due to tidal channel lateral swing and human activities. The significant negative correlation(r=-0.20, p<0.001) was found between FVC and TCD, which shows vegetation is restricted to grow in higher TCD area corresponding to lower elevation mainly occupied by S. mariqueter communities. The maximum occurrence frequency of this species reaches to 97% at the salt marsh with TCD more than 8 m/m2.
The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt marsh. Since the exotic species Spartina alterniflora(S. alterniflora) was introduced in 1995, a rapid expansion has occurred at Chongming Dongtan Nature Reserve(CDNR) in the Changjiang(Yangtze) River Estuary, China. Several important vegetation-environment factors including soil elevation, tidal channels density(TCD), vegetation classification and fractional vegetation cover(FVC) were extracted by remote sensing method combined with field measurement. To ignore the details in interaction between biological and physical process, the relationship between them was discussed at a large scale of the whole saltmarsh. The results showed that Scirpus mariqueter(S. mariqueter) can endure the greatest elevation variance with 0.33 m throughout the marsh in CDNR. But it is dominant in the area less than 2.5 m with the occurrence frequency reaching 98%. S. alterniflora has usually been found on the most elevated soils higher than 3.5 m but has a narrow spatial distribution. The rapid decrease of S. mariqueter can be explained by stronger competitive capacity of S. alterniflora on the high tidal flat. FVC increases with elevation which shows significant correlation with elevation(r=0.30, p<0.001). But the frequency distribution of FVC indicates that vegetation is not well developed on both elevated banks near tidal channels from the whole scale mainly due to tidal channel lateral swing and human activities. The significant negative correlation(r=-0.20, p<0.001) was found between FVC and TCD, which shows vegetation is restricted to grow in higher TCD area corresponding to lower elevation mainly occupied by S. mariqueter communities. The maximum occurrence frequency of this species reaches to 97% at the salt marsh with TCD more than 8 m/m2.
2016, 35(4): 35-43.
doi: 10.1007/s13131-016-0836-7
Abstract:
Spartina alterniflora is one of exotic plants along the coastal region in China. It was introduced as an important engineering approach to ecological restoration in the later 1970s. However, owing to its good adaptability and strong reproductive capacity, the introduced species is explosively spreading along the coastal region quickly and resulting in a significant impact on the health and safety of coastal wetland ecosystems. It is imperative to quantify the spatial extent and the rate of S. alterniflora sprawl in order to assess its ecological damages and economic impacts. Remote sensing techniques have been used to address these challenges but large unsuccessful due to mixed spectral properties. In this study, a hybrid method was proposed for S. alterniflora detection using medium resolution remote sensing images by integrating both spatial and spectral features of S. alterniflora. The hybrid method consists of two phases:(1) delineation of intertidal zone as the potential area of S. alterniflora distribution and(2) extraction of S. alterniflora fraction distribution with a mixture pixel analysis. The proposed method was tested at the Xiangshan Bay on the east coastal region of Zhejiang Province, China, and mapped the spatial extent of S. alterniflora with Landsat datasets in the 2003, 2009 and 2014. The results showed that, the S. alterniflora has grown exponentially over past 10 years. In 2003, the total area of S. alterniflora was about 590 hm2, but quickly reached to 1745 hm2 in 2009, and 5715 hm2 in 2014. With a rate of approximately 10-folds growth within a decade, the invasive species almost occupied all muddy beaches to become the most dominant coastal salt vegetation in this region. It is believed that the strong biological reproductive capacity was the primary reason for such quick spread and at the same time human reclamation activities were also believed to have facilitated the environmental conditions for S. alterniflora sprawl.
Spartina alterniflora is one of exotic plants along the coastal region in China. It was introduced as an important engineering approach to ecological restoration in the later 1970s. However, owing to its good adaptability and strong reproductive capacity, the introduced species is explosively spreading along the coastal region quickly and resulting in a significant impact on the health and safety of coastal wetland ecosystems. It is imperative to quantify the spatial extent and the rate of S. alterniflora sprawl in order to assess its ecological damages and economic impacts. Remote sensing techniques have been used to address these challenges but large unsuccessful due to mixed spectral properties. In this study, a hybrid method was proposed for S. alterniflora detection using medium resolution remote sensing images by integrating both spatial and spectral features of S. alterniflora. The hybrid method consists of two phases:(1) delineation of intertidal zone as the potential area of S. alterniflora distribution and(2) extraction of S. alterniflora fraction distribution with a mixture pixel analysis. The proposed method was tested at the Xiangshan Bay on the east coastal region of Zhejiang Province, China, and mapped the spatial extent of S. alterniflora with Landsat datasets in the 2003, 2009 and 2014. The results showed that, the S. alterniflora has grown exponentially over past 10 years. In 2003, the total area of S. alterniflora was about 590 hm2, but quickly reached to 1745 hm2 in 2009, and 5715 hm2 in 2014. With a rate of approximately 10-folds growth within a decade, the invasive species almost occupied all muddy beaches to become the most dominant coastal salt vegetation in this region. It is believed that the strong biological reproductive capacity was the primary reason for such quick spread and at the same time human reclamation activities were also believed to have facilitated the environmental conditions for S. alterniflora sprawl.
2016, 35(4): 44-50.
doi: 10.1007/s13131-016-0835-8
Abstract:
β-thymosins, a family of highly conserved peptides, play a vital role in wound-healing, angiogenesis, antimicrobial process and antiviral immunity. Three novel β-thymosin-repeat proteins, named mjthm4, mjthm3 and mjthm2, were cloned from Marsupenaeus japonicus using expressed sequence tags(EST) from suppression subtractive hybridization. The mjthm4, mjthm3 and mjthm2 cDNAs possessed open reading frames that encoded 166, 128 and 90 amino acid residue polypeptides and contained four, three and two β-thymosin actin binding modules, respectively. Blast analysis demonstrated that mjthm4, mjthm3 and mjthm2 shared high homology with known invertebrate multi-repeat β-thymosins. These proteins are ubiquitously expressed in all of the examined tissues, and the transcriptional levels were highest in the intestine. Further investigation revealed that mjthm4, mjthm3 and mjthm2 were remarkably up-regulated 6 h after WSSV infection. Moreover, while mjthm4 transcriptional levels displayed no changes, mjthm3 and mjthm2 levels decreased in the virus-resistant shrimps. The results indicate that mjthm4, mjthm3 and mjthm2 are novel multi-repeat β-thymosin homologues, have a close relationship with WSSV infection, and might contribute to a better understanding of host defense and/or virus invasion interactions in shrimps.
β-thymosins, a family of highly conserved peptides, play a vital role in wound-healing, angiogenesis, antimicrobial process and antiviral immunity. Three novel β-thymosin-repeat proteins, named mjthm4, mjthm3 and mjthm2, were cloned from Marsupenaeus japonicus using expressed sequence tags(EST) from suppression subtractive hybridization. The mjthm4, mjthm3 and mjthm2 cDNAs possessed open reading frames that encoded 166, 128 and 90 amino acid residue polypeptides and contained four, three and two β-thymosin actin binding modules, respectively. Blast analysis demonstrated that mjthm4, mjthm3 and mjthm2 shared high homology with known invertebrate multi-repeat β-thymosins. These proteins are ubiquitously expressed in all of the examined tissues, and the transcriptional levels were highest in the intestine. Further investigation revealed that mjthm4, mjthm3 and mjthm2 were remarkably up-regulated 6 h after WSSV infection. Moreover, while mjthm4 transcriptional levels displayed no changes, mjthm3 and mjthm2 levels decreased in the virus-resistant shrimps. The results indicate that mjthm4, mjthm3 and mjthm2 are novel multi-repeat β-thymosin homologues, have a close relationship with WSSV infection, and might contribute to a better understanding of host defense and/or virus invasion interactions in shrimps.
2016, 35(4): 51-57.
doi: 10.1007/s13131-016-0838-5
Abstract:
Superoxide dismutase(SOD) is a crucial antioxidant enzyme playing the first defense line in antioxidant pathways against reactive oxygen species in various organisms including marine invertebrates. There exist mainly two specific forms, Cu/Zn-SOD(SOD1) and Mn-SOD(SOD2), in eukaryotes. SODs are known to be concurrently modulated by a variety of environmental stressors. By using central composite experimental design and response surface method, the joint effects of water temperature(18-34℃) and copper ion concentration(0.1-1.5 mg/L) on the total SOD activity in the digestive gland of Crassostrea ariakensis were studied. The results showed that the linear effect of temperature was highly significant(P<0.01), the quadratic effect of temperature was significant(P<0.05); the linear effect of copper ion concentration was not significant(P>0.05), while the quadratic effect of copper ion concentration was highly significant(P<0.01); the interactive effect of temperature and copper ion concentration was not significant(P>0.05); the effect of temperature was greater than that of copper ion concentration. The model equation of digestive gland SOD enzyme activity towards the two factors of interest was established, with R2 and predictive R2 as high as 0.9616 and 0.8207, respectively, suggesting that the goodness-of-fit to experimental data be very satisfactory, and could be applied to prediction of digestive gland SOD activity in C. ariakensis under the conditions of the experiment. Our results would be conducive to addressing the health of aquatic animals and/or to detecting environmental problems by taking SOD as a potential bioindicator.
Superoxide dismutase(SOD) is a crucial antioxidant enzyme playing the first defense line in antioxidant pathways against reactive oxygen species in various organisms including marine invertebrates. There exist mainly two specific forms, Cu/Zn-SOD(SOD1) and Mn-SOD(SOD2), in eukaryotes. SODs are known to be concurrently modulated by a variety of environmental stressors. By using central composite experimental design and response surface method, the joint effects of water temperature(18-34℃) and copper ion concentration(0.1-1.5 mg/L) on the total SOD activity in the digestive gland of Crassostrea ariakensis were studied. The results showed that the linear effect of temperature was highly significant(P<0.01), the quadratic effect of temperature was significant(P<0.05); the linear effect of copper ion concentration was not significant(P>0.05), while the quadratic effect of copper ion concentration was highly significant(P<0.01); the interactive effect of temperature and copper ion concentration was not significant(P>0.05); the effect of temperature was greater than that of copper ion concentration. The model equation of digestive gland SOD enzyme activity towards the two factors of interest was established, with R2 and predictive R2 as high as 0.9616 and 0.8207, respectively, suggesting that the goodness-of-fit to experimental data be very satisfactory, and could be applied to prediction of digestive gland SOD activity in C. ariakensis under the conditions of the experiment. Our results would be conducive to addressing the health of aquatic animals and/or to detecting environmental problems by taking SOD as a potential bioindicator.
2016, 35(4): 58-62.
doi: 10.1007/s13131-016-0834-9
Abstract:
The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber(A. japonicus) and prawn(Penaeus japonica) polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from(-25.47±0.20)‰ to(-16.48±0.17)‰(mean±SD), and δ15N ranged from(4.23±0.49)‰ to(12.44±0.09)‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was(2.75±0.08). P. japonica, A. japonicus, F. chinensis, Synechogobius hasta and Neomysis japonica were in the 3rd trophic level(2-3); jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level(1-2); and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level(0-1).
The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber(A. japonicus) and prawn(Penaeus japonica) polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from(-25.47±0.20)‰ to(-16.48±0.17)‰(mean±SD), and δ15N ranged from(4.23±0.49)‰ to(12.44±0.09)‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was(2.75±0.08). P. japonica, A. japonicus, F. chinensis, Synechogobius hasta and Neomysis japonica were in the 3rd trophic level(2-3); jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level(1-2); and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level(0-1).
2016, 35(4): 63-73.
doi: 10.1007/s13131-016-0822-0
Abstract:
Multispecies ecological models have been used for predicting the effects of fishing activity and evaluating the performance of management strategies. Size-spectrum models are one type of physiologically-structured ecological model that provide a feasible approach to describing fish communities in terms of individual dietary variation and ontogenetic niche shift. Despite the potential of ecological models in improving our understanding of ecosystems, their application is usually limited for data-poor fisheries. As a first step in implementing ecosystem-based fisheries management(EBFM), this study built a size-spectrum model for the fish community in the Haizhou Bay, China. We describe data collection procedures and model parameterization to facilitate the implementation of such size-spectrum models for future studies of data-poor ecosystems. The effects of fishing on the ecosystem were exemplified with a range of fishing effort and were monitored with a set of ecological indicators. Total community biomass, biodiversity index, W-statistic, LFI(Large fish index), MeanW(mean body weight) and Slope(slope of community size spectra) showed a strong non-linear pattern in response to fishing pressure, and largest fishing effort did not generate the most drastic responses in certain scenarios. We emphasize the value and feasibility of developing size-spectrum models to capture ecological dynamics and suggest limitations as well as potential for model improvement. This study aims to promote a wide use of this type of model in support of EBFM.
Multispecies ecological models have been used for predicting the effects of fishing activity and evaluating the performance of management strategies. Size-spectrum models are one type of physiologically-structured ecological model that provide a feasible approach to describing fish communities in terms of individual dietary variation and ontogenetic niche shift. Despite the potential of ecological models in improving our understanding of ecosystems, their application is usually limited for data-poor fisheries. As a first step in implementing ecosystem-based fisheries management(EBFM), this study built a size-spectrum model for the fish community in the Haizhou Bay, China. We describe data collection procedures and model parameterization to facilitate the implementation of such size-spectrum models for future studies of data-poor ecosystems. The effects of fishing on the ecosystem were exemplified with a range of fishing effort and were monitored with a set of ecological indicators. Total community biomass, biodiversity index, W-statistic, LFI(Large fish index), MeanW(mean body weight) and Slope(slope of community size spectra) showed a strong non-linear pattern in response to fishing pressure, and largest fishing effort did not generate the most drastic responses in certain scenarios. We emphasize the value and feasibility of developing size-spectrum models to capture ecological dynamics and suggest limitations as well as potential for model improvement. This study aims to promote a wide use of this type of model in support of EBFM.
2016, 35(4): 74-81.
doi: 10.1007/s13131-015-0767-8
Abstract:
The pelagic species is closely related to the marine environmental factors, and establishment of forecasting model of fishing ground with high accuracy is an important content for pelagic fishery. The chub mackerel(Scomber japonicus) in the Yellow Sea and East China Sea is an important fishing target for Chinese lighting purse seine fishery. Based on the fishery data from China's mainland large-type lighting purse seine fishery for chub mackerel during the period of 2003 to 2010 and the environmental data including sea surface temperature(SST), gradient of the sea surface temperature(GSST), sea surface height(SSH) and geostrophic velocity(GV), we attempt to establish one new forecasting model of fishing ground based on boosted regression trees. In this study, the fishing areas with fishing effort is considered as one fishing ground, and the areas with no fishing ground are randomly selected from a background field, in which the fishing areas have no records in the logbooks. The performance of the forecasting model of fishing ground is evaluated with the testing data from the actual fishing data in 2011. The results show that the forecasting model of fishing ground has a high prediction performance, and the area under receiver operating curve(AUC) attains 0.897. The predicted fishing grounds are coincided with the actual fishing locations in 2011, and the movement route is also the same as the shift of fishing vessels, which indicates that this forecasting model based on the boosted regression trees can be used to effectively forecast the fishing ground of chub mackerel in the Yellow Sea and East China Sea.
The pelagic species is closely related to the marine environmental factors, and establishment of forecasting model of fishing ground with high accuracy is an important content for pelagic fishery. The chub mackerel(Scomber japonicus) in the Yellow Sea and East China Sea is an important fishing target for Chinese lighting purse seine fishery. Based on the fishery data from China's mainland large-type lighting purse seine fishery for chub mackerel during the period of 2003 to 2010 and the environmental data including sea surface temperature(SST), gradient of the sea surface temperature(GSST), sea surface height(SSH) and geostrophic velocity(GV), we attempt to establish one new forecasting model of fishing ground based on boosted regression trees. In this study, the fishing areas with fishing effort is considered as one fishing ground, and the areas with no fishing ground are randomly selected from a background field, in which the fishing areas have no records in the logbooks. The performance of the forecasting model of fishing ground is evaluated with the testing data from the actual fishing data in 2011. The results show that the forecasting model of fishing ground has a high prediction performance, and the area under receiver operating curve(AUC) attains 0.897. The predicted fishing grounds are coincided with the actual fishing locations in 2011, and the movement route is also the same as the shift of fishing vessels, which indicates that this forecasting model based on the boosted regression trees can be used to effectively forecast the fishing ground of chub mackerel in the Yellow Sea and East China Sea.
2016, 35(4): 82-88.
doi: 10.1007/s13131-015-0728-2
Abstract:
The relationship between spatial patterns of macrobenthos community characteristics and environmental conditions(salinity, temperature, dissolved oxygen, organic matter content, sand, silt and clay) was investigated throughout the Gorgan Bay in June 2010. Principal components analysis(PCA) based on environmental data separated eastern and western stations. The maximum(4500 ind./m2) and minimum(411 ind./m2) densities were observed at Stas 1 and 6, respectively. Polychaeta was the major group and Streblospio gynobranchiata was dominant species in the bay. According to Distance Based Linear Models results, macrofaunal total density was correlated with silt percentage and salinity and these two factors explaining 64% of the variability while macrofaunal community structure just correlated with salinity(22% total variation). In general, western part of the bay showed the highest number of species and biodiversity while, the highest density was found at Sta. 1 and in the middle part of the bay. Furthermore, relationship between diversity indices and macrobenthic species with measured factors is also discussed. Our results confirm the effect of salinity as an important factor on distribution of macrobenthic fauna in south Caspian brackish waters.
The relationship between spatial patterns of macrobenthos community characteristics and environmental conditions(salinity, temperature, dissolved oxygen, organic matter content, sand, silt and clay) was investigated throughout the Gorgan Bay in June 2010. Principal components analysis(PCA) based on environmental data separated eastern and western stations. The maximum(4500 ind./m2) and minimum(411 ind./m2) densities were observed at Stas 1 and 6, respectively. Polychaeta was the major group and Streblospio gynobranchiata was dominant species in the bay. According to Distance Based Linear Models results, macrofaunal total density was correlated with silt percentage and salinity and these two factors explaining 64% of the variability while macrofaunal community structure just correlated with salinity(22% total variation). In general, western part of the bay showed the highest number of species and biodiversity while, the highest density was found at Sta. 1 and in the middle part of the bay. Furthermore, relationship between diversity indices and macrobenthic species with measured factors is also discussed. Our results confirm the effect of salinity as an important factor on distribution of macrobenthic fauna in south Caspian brackish waters.
2016, 35(4): 89-98.
doi: 10.1007/s13131-016-0832-y
Abstract:
Maturity index(MI), based on nematode life strategies, has been proposed in 1990 to assess the possible variations of the terrestrial and freshwater nematode assemblages induced by anthropogenic activities. It was subsequently applied also to marine ecosystems and, even if comparatively not yet very popular, it offers a good method to assess the ecological quality in relation to a wide range of anthropogenic drivers. However, few data are available on its response to physical stress, a key factor especially in the coastal areas. In this study, marine nematode genera from two study cases carried out in Maldives are used to test both MI and life strategy traits(i.e., c-p classes) for detecting the effects of physical disturbance. The results confirm that nematodes are well adapted to physical stress showing a general high rate of recovery. C-p scaling and MI did not seem to be appropriate for revealing this disturbance type probably because there are no empirical evidences on the life strategy of several genera, and a possible differential response to various disturbance types may be hypothesized.
Maturity index(MI), based on nematode life strategies, has been proposed in 1990 to assess the possible variations of the terrestrial and freshwater nematode assemblages induced by anthropogenic activities. It was subsequently applied also to marine ecosystems and, even if comparatively not yet very popular, it offers a good method to assess the ecological quality in relation to a wide range of anthropogenic drivers. However, few data are available on its response to physical stress, a key factor especially in the coastal areas. In this study, marine nematode genera from two study cases carried out in Maldives are used to test both MI and life strategy traits(i.e., c-p classes) for detecting the effects of physical disturbance. The results confirm that nematodes are well adapted to physical stress showing a general high rate of recovery. C-p scaling and MI did not seem to be appropriate for revealing this disturbance type probably because there are no empirical evidences on the life strategy of several genera, and a possible differential response to various disturbance types may be hypothesized.
Community structure and spatial-temporal variation of netz-phytoplankton in the Bering Sea in summer
2016, 35(4): 99-107.
doi: 10.1007/s13131-016-0833-x
Abstract:
Marine biodiversity is changing in response to altered physical environment, subsequent ecological changes as well as anthropogenic disturbances. In this study, phytoplankton samples in situ collected in the Bering Sea in July of 1999 and 2010 were analyzed to obtain phytoplankton community structure and spatial-temporal variation between the beginning and end of this decade, and the correlation of phytoplankton community dynamics and environmental factors was investigated. A total of 5 divisions, 58 genera and 153 species of phytoplankton belonging to 3 ecological groups were identified. The vast majority of phytoplankton consisted of diatoms accounting for 66.7% of the total species and 95.2% of the total abundance. Considering differentiation in spatial extent and phytoplankton sample types, there were subtle changes in species composition, large altering in abundance and significant variation in spatial distribution between two surveys. The abundance peak area was located at the Bering Strait while sub peak was found at the Bering Sea Basin. The boreal-temperate diatom was the dominant flora, which was subsequently replaced by eurythermal and frigid-water diatom. Phytoplankton community in the Bering Sea was not a simplex uniform community but composed of deep-ocean assemblage and neritic assemblage. The deep-ocean assemblage was located in the northwestern Pacific Ocean and Bering Sea Basin, dominated by boreal-temperate species(Neodenticula seminae, Thalassiothrix longissima, Amphiprora hyperborean, Chaetoceros atlanticus, Thalassiosira trifulta, etc.) and eurychoric species(Thalassionema nitzschioides, Ch. compressus, Rhizosolenia styliformis, etc.), and characterized by low abundance, even inter-species abundance allocations, diverse dominant species and high species diversity. The neritic assemblage was distributed on the continental shelf and slope of Bering Sea and was mainly composed of frigid-water species(Th. nordenskiöldii, Ch. furcellatus, Ch. socialis, Bacteriosira fragilis, etc.) and eurythermal and euryhaline species(L. danicus, Ch. curvisetus, Coscinodiscus curvatulus, etc.), and it was characterized by high abundance, uneven inter-species allocations, prominent dominant species and low species diversity. Spatial-temporal variation of species composition and abundance of phytoplankton in the Bering Sea was directly controlled by surface circulation, nutrient supply and ice edge.
Marine biodiversity is changing in response to altered physical environment, subsequent ecological changes as well as anthropogenic disturbances. In this study, phytoplankton samples in situ collected in the Bering Sea in July of 1999 and 2010 were analyzed to obtain phytoplankton community structure and spatial-temporal variation between the beginning and end of this decade, and the correlation of phytoplankton community dynamics and environmental factors was investigated. A total of 5 divisions, 58 genera and 153 species of phytoplankton belonging to 3 ecological groups were identified. The vast majority of phytoplankton consisted of diatoms accounting for 66.7% of the total species and 95.2% of the total abundance. Considering differentiation in spatial extent and phytoplankton sample types, there were subtle changes in species composition, large altering in abundance and significant variation in spatial distribution between two surveys. The abundance peak area was located at the Bering Strait while sub peak was found at the Bering Sea Basin. The boreal-temperate diatom was the dominant flora, which was subsequently replaced by eurythermal and frigid-water diatom. Phytoplankton community in the Bering Sea was not a simplex uniform community but composed of deep-ocean assemblage and neritic assemblage. The deep-ocean assemblage was located in the northwestern Pacific Ocean and Bering Sea Basin, dominated by boreal-temperate species(Neodenticula seminae, Thalassiothrix longissima, Amphiprora hyperborean, Chaetoceros atlanticus, Thalassiosira trifulta, etc.) and eurychoric species(Thalassionema nitzschioides, Ch. compressus, Rhizosolenia styliformis, etc.), and characterized by low abundance, even inter-species abundance allocations, diverse dominant species and high species diversity. The neritic assemblage was distributed on the continental shelf and slope of Bering Sea and was mainly composed of frigid-water species(Th. nordenskiöldii, Ch. furcellatus, Ch. socialis, Bacteriosira fragilis, etc.) and eurythermal and euryhaline species(L. danicus, Ch. curvisetus, Coscinodiscus curvatulus, etc.), and it was characterized by high abundance, uneven inter-species allocations, prominent dominant species and low species diversity. Spatial-temporal variation of species composition and abundance of phytoplankton in the Bering Sea was directly controlled by surface circulation, nutrient supply and ice edge.
2016, 35(4): 108-117.
doi: 10.1007/s13131-016-0823-z
Abstract:
The classification and identification for Protoperidinium species are the most difficult work during its taxonomic study. In this research, taxonomic status of Protoperidinium was clarified by tracing its taxonomic history, 23 species belong to genus Protoperidinium on the coasts of China were preliminarily identified, and morphological description and plate patterns were given for each species. The key differences of similar species were also discussed in this study, we believe that P. oceanicum and P. murry, P. tumidum and P. fatulipes, P. globules and P. majus are separate species; P. diabolum should be treated as the valid name instead of the reported names Peridinium globosum or Peridinium longipes; the taxonomic relationship between P. punctulatum and P. subinerme requires further study.
The classification and identification for Protoperidinium species are the most difficult work during its taxonomic study. In this research, taxonomic status of Protoperidinium was clarified by tracing its taxonomic history, 23 species belong to genus Protoperidinium on the coasts of China were preliminarily identified, and morphological description and plate patterns were given for each species. The key differences of similar species were also discussed in this study, we believe that P. oceanicum and P. murry, P. tumidum and P. fatulipes, P. globules and P. majus are separate species; P. diabolum should be treated as the valid name instead of the reported names Peridinium globosum or Peridinium longipes; the taxonomic relationship between P. punctulatum and P. subinerme requires further study.
2016, 35(4): 118-123.
doi: 10.1007/s13131-016-0841-x
Abstract:
Green macroalgae Chaetomorpha aerea and C. linum are taxonomically confused. In this paper, we tried morphological and molecular analyses to separate these two species. C. aerea and C. linum can be distinguished from morphological characteritics, such as frond dimension, cells size and shape, their mean length/width ratios(LWR), and cell walls constriction. Thalli of C. aerea attenuate basipetally, with diameter 270-500μm at upper portion, 160-360μm at middle portion, 100-160μm at basal portion. For the upper part, the length of cells is less than their diameter. Cell walls usually constrict at the dissepiments, which are pellucid or colorless and give the filament beaded appearance. In contrast, thalli of C. linum often have a constant diameter of 90-300μm within the same individual, cell walls usually do not constrict and cells are cylindrical or barrel shaped. The LWR is larger than that of C. aerea. Results show that the pairwise distance between two species is 3.6%-3.7% for 18S rRNA gene and 53.5%-54.3% for ITS region. In phylogeny, they distribute at distant clades, which confirms a genetic divergence at molecular level. In addition, morphological data indicates that filament diameter of C. linum samples is highly variable, ranging from 90μm to 300μm. Then these two species can be considered as separate species.
Green macroalgae Chaetomorpha aerea and C. linum are taxonomically confused. In this paper, we tried morphological and molecular analyses to separate these two species. C. aerea and C. linum can be distinguished from morphological characteritics, such as frond dimension, cells size and shape, their mean length/width ratios(LWR), and cell walls constriction. Thalli of C. aerea attenuate basipetally, with diameter 270-500μm at upper portion, 160-360μm at middle portion, 100-160μm at basal portion. For the upper part, the length of cells is less than their diameter. Cell walls usually constrict at the dissepiments, which are pellucid or colorless and give the filament beaded appearance. In contrast, thalli of C. linum often have a constant diameter of 90-300μm within the same individual, cell walls usually do not constrict and cells are cylindrical or barrel shaped. The LWR is larger than that of C. aerea. Results show that the pairwise distance between two species is 3.6%-3.7% for 18S rRNA gene and 53.5%-54.3% for ITS region. In phylogeny, they distribute at distant clades, which confirms a genetic divergence at molecular level. In addition, morphological data indicates that filament diameter of C. linum samples is highly variable, ranging from 90μm to 300μm. Then these two species can be considered as separate species.
2016, 35(4): 124-132.
doi: 10.1007/s13131-016-0809-x
Abstract:
The predictability of marine ecosystem dynamics models is one of the most vital factors to limit their practical applications, of which the stability is the fundamental condition. In order to discuss the stability and Hopf bifurcation of marine ecosystem dynamics models, an approach based on a theorem termed dimension reduction was proposed and further applied in the mass-conservative nutrient-phytoplankton-zooplankton-detritus(NPZD) model in this paper. Results showed that the nonsingular equilibrium point of NPZD model was analytically stable in use of the dimension reduction theorem and the Hopf bifurcation might occur when model parameters changed along the threshold values. The analytical results of the NPZD model were further verified by numerical simulation in this study. It can be concluded that this approach based on the dimension reduction theorem is well applicable to the theoretical analysis of a kind of stability problems and Hopf bifurcation of mass-conservative systems.
The predictability of marine ecosystem dynamics models is one of the most vital factors to limit their practical applications, of which the stability is the fundamental condition. In order to discuss the stability and Hopf bifurcation of marine ecosystem dynamics models, an approach based on a theorem termed dimension reduction was proposed and further applied in the mass-conservative nutrient-phytoplankton-zooplankton-detritus(NPZD) model in this paper. Results showed that the nonsingular equilibrium point of NPZD model was analytically stable in use of the dimension reduction theorem and the Hopf bifurcation might occur when model parameters changed along the threshold values. The analytical results of the NPZD model were further verified by numerical simulation in this study. It can be concluded that this approach based on the dimension reduction theorem is well applicable to the theoretical analysis of a kind of stability problems and Hopf bifurcation of mass-conservative systems.
