2017 Vol. 39, No. 6
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2017, 39(6): .
Abstract:
2017, 39(6): 1-9.
doi: 10.3969/j.issn.0253-4193.2017.06.001
Abstract:
Based on the SeaWiFS and MODIS chlorophyll a (Chl a) concentration data from 1998 to 2013, the interannual variability of the high Chl a concentration strip in the western South China Sea(SCS) during summer is investigated. In summer,under the effect of the eastward current, the Chl a and the nutrients are advected offshore into the open SCS, which contributes to forming the high Chl a concentration strip, whose distribution pattern seems in accord with the direction of the eastward current. Our analysis shows that in the study region,monsoon in the south of 13°N plays a significant role in determining the distribution of the chlorophyll with 1 week delay, and the interannual variability of wind anomaly results in the variability of the high chlorophyll concentration strip. When the area is controlled by anomalous northeast (southwest) monsoon, the strip moves northward (southward).
Based on the SeaWiFS and MODIS chlorophyll a (Chl a) concentration data from 1998 to 2013, the interannual variability of the high Chl a concentration strip in the western South China Sea(SCS) during summer is investigated. In summer,under the effect of the eastward current, the Chl a and the nutrients are advected offshore into the open SCS, which contributes to forming the high Chl a concentration strip, whose distribution pattern seems in accord with the direction of the eastward current. Our analysis shows that in the study region,monsoon in the south of 13°N plays a significant role in determining the distribution of the chlorophyll with 1 week delay, and the interannual variability of wind anomaly results in the variability of the high chlorophyll concentration strip. When the area is controlled by anomalous northeast (southwest) monsoon, the strip moves northward (southward).
2017, 39(6): 10-20.
doi: 10.3969/j.issn.0253-4193.2017.06.002
Abstract:
By analyzing 25 stations' sea level data, this paper preliminarily investigate the characteristics of residual water level variation along China coast and its relation to sea level change during 1980-2012. The results show: (1) Residual water level along China coast has significant seasonal variation. As the weather condition is the same in the adjacent stations, the procedure of residual water level variation is similar. From spatial distribution, residual water level variation along China coast presents obviously regional characteristics, and the amplitude of variation is big in middle, small in south and north. From Yangtze River to the coastal region of Guangdong, the amplitude of residual water level variation is largest, and the average annual range is 5.0-7.5 cm. From the coast of Hainan to the coast of Beibu Gulf, the amplitude of residual water level variation is larger, and the average annual range is 4.0-5.5 cm. From the coast of Bohai Sea to the coast of Yellow Sea, the amplitude of residual water level variation is small, and the average annual range is 3.3-3.5 cm. (2) From temporal variation, average annual residual water level basically has no tendency change during 1980-2012, but it has a 2-5 a periodic signal. The oscillation amplitude is 0.1 cm. Correlation coefficient between the monthly residual water level time sequence and Niño3.4 index is -0.5, which passed the significance test. It shows that the monthly residual water level is associated with ENSO. (3) Residual water level time variation and spatial distribution characteristic along China coast are all different from sea level. 1980-2012, the rise rate of China coast sea level is 2.9 mm/a, but there is almost no long-term tendency change in residual water level. In addition, the seasonal variation of residual water level and sea level is inconsistent in time and area. (4) Residual water level has an impact on short-term sea level change, and the magnitude of the impact is based on its residual water level. The long time increasing water make the sea level higher, and its maximum contribution rate is 65%. On the contrary, the long time decreasing water make the sea level lower.
By analyzing 25 stations' sea level data, this paper preliminarily investigate the characteristics of residual water level variation along China coast and its relation to sea level change during 1980-2012. The results show: (1) Residual water level along China coast has significant seasonal variation. As the weather condition is the same in the adjacent stations, the procedure of residual water level variation is similar. From spatial distribution, residual water level variation along China coast presents obviously regional characteristics, and the amplitude of variation is big in middle, small in south and north. From Yangtze River to the coastal region of Guangdong, the amplitude of residual water level variation is largest, and the average annual range is 5.0-7.5 cm. From the coast of Hainan to the coast of Beibu Gulf, the amplitude of residual water level variation is larger, and the average annual range is 4.0-5.5 cm. From the coast of Bohai Sea to the coast of Yellow Sea, the amplitude of residual water level variation is small, and the average annual range is 3.3-3.5 cm. (2) From temporal variation, average annual residual water level basically has no tendency change during 1980-2012, but it has a 2-5 a periodic signal. The oscillation amplitude is 0.1 cm. Correlation coefficient between the monthly residual water level time sequence and Niño3.4 index is -0.5, which passed the significance test. It shows that the monthly residual water level is associated with ENSO. (3) Residual water level time variation and spatial distribution characteristic along China coast are all different from sea level. 1980-2012, the rise rate of China coast sea level is 2.9 mm/a, but there is almost no long-term tendency change in residual water level. In addition, the seasonal variation of residual water level and sea level is inconsistent in time and area. (4) Residual water level has an impact on short-term sea level change, and the magnitude of the impact is based on its residual water level. The long time increasing water make the sea level higher, and its maximum contribution rate is 65%. On the contrary, the long time decreasing water make the sea level lower.
2017, 39(6): 21-32.
doi: 10.3969/j.issn.0253-4193.2017.06.003
Abstract:
Absorption and fluorescence spectroscopies were used to examine the distribution, composition, sources and mixing behavior of colored dissolved organic matter (CDOM) in the Changjiang estuary in March and July 2015. The characteristics of fluorescent components of CDOM in the Changjiang Estuary were determined by fluorescence excitation emission matrix spectroscopy (EEMs) combined with parallel factor analysis (PARAFAC).Three humic-like components, i.e., C1(260,375/490 nm), C2(365/440 nm) and C3(330/400 nm) and one protein-like component C4 (295/345 nm) were identified by EEMs-PARAFAC. The distribution and non-conservative mixing behavior of these four components were consistent with the total fluorescence intensity (TFI) both in March and July 2015, first increasing and then gradually decreasing from the inner estuary to outside the estuary, with the additional behavior and highest value observed at Turbidity Maximum Zone and removal process outside the estuary. Ranging from 1.12 to 7.19 in March and 0.87 to 6.71 in July, the humification index (HIX) values showed that CDOM in March had a higher degree of humification than that in July. The biological index (BIX) values ranged from 0.76 to 1.11 and 0.62 to 1.15 in March and July respectively, suggesting a greater contribution of biological activities to CDOM in July. In March, The average value of α(355) was 0.55 m-1, lower than that in July (0.61 m-1), reflecting higher content of CDOM in summer. The seasonal variation of SR was not obvious, increasing along the salinity in both seasons, which indicated that the average molecular weight of CDOM increased from the inside to the outside of the Changjiang Estuary.
Absorption and fluorescence spectroscopies were used to examine the distribution, composition, sources and mixing behavior of colored dissolved organic matter (CDOM) in the Changjiang estuary in March and July 2015. The characteristics of fluorescent components of CDOM in the Changjiang Estuary were determined by fluorescence excitation emission matrix spectroscopy (EEMs) combined with parallel factor analysis (PARAFAC).Three humic-like components, i.e., C1(260,375/490 nm), C2(365/440 nm) and C3(330/400 nm) and one protein-like component C4 (295/345 nm) were identified by EEMs-PARAFAC. The distribution and non-conservative mixing behavior of these four components were consistent with the total fluorescence intensity (TFI) both in March and July 2015, first increasing and then gradually decreasing from the inner estuary to outside the estuary, with the additional behavior and highest value observed at Turbidity Maximum Zone and removal process outside the estuary. Ranging from 1.12 to 7.19 in March and 0.87 to 6.71 in July, the humification index (HIX) values showed that CDOM in March had a higher degree of humification than that in July. The biological index (BIX) values ranged from 0.76 to 1.11 and 0.62 to 1.15 in March and July respectively, suggesting a greater contribution of biological activities to CDOM in July. In March, The average value of α(355) was 0.55 m-1, lower than that in July (0.61 m-1), reflecting higher content of CDOM in summer. The seasonal variation of SR was not obvious, increasing along the salinity in both seasons, which indicated that the average molecular weight of CDOM increased from the inside to the outside of the Changjiang Estuary.
2017, 39(6): 33-42.
doi: 10.3969/j.issn.0253-4193.2017.06.004
Abstract:
The morphological attributes of aggregate particles formed by modified clays (MCs) with algae can theoretically guide the dosage and usage of the MCs in the red tide treatment. In this study, we discussed the feasibility of particle morphological measurement on evaluating the algal removal efficiency of MCs. We measured surface electricity, sizes and structures of the aggregate particles using laser technique and electron microscopy. Results showed that current methods reliably detect the reversion of clay particles surface electricity after being modified, the variation of particles grade when various clays were dispersed in different solvents, and the fine microscopic structures of aggregates formed between MCs and algae. However, the bigger particles which did not carry a corresponding ratio of cells to sediment had a great impact in system on the present morphological measurements. There were no significant correlations between the particle sizes and the algal removal efficiencies. Our observations suggest that the current methods were not sensitive enough to reveal the morphological variation of MCs particles and the present resolved characteristics could not denote the algal removal efficiency. Thus it's in urgent need of new methods to analyze the characteristics of aggregates formed by MCs and algal cells.
The morphological attributes of aggregate particles formed by modified clays (MCs) with algae can theoretically guide the dosage and usage of the MCs in the red tide treatment. In this study, we discussed the feasibility of particle morphological measurement on evaluating the algal removal efficiency of MCs. We measured surface electricity, sizes and structures of the aggregate particles using laser technique and electron microscopy. Results showed that current methods reliably detect the reversion of clay particles surface electricity after being modified, the variation of particles grade when various clays were dispersed in different solvents, and the fine microscopic structures of aggregates formed between MCs and algae. However, the bigger particles which did not carry a corresponding ratio of cells to sediment had a great impact in system on the present morphological measurements. There were no significant correlations between the particle sizes and the algal removal efficiencies. Our observations suggest that the current methods were not sensitive enough to reveal the morphological variation of MCs particles and the present resolved characteristics could not denote the algal removal efficiency. Thus it's in urgent need of new methods to analyze the characteristics of aggregates formed by MCs and algal cells.
2017, 39(6): 43-54.
doi: 10.3969/j.issn.0253-4193.2017.06.005
Abstract:
A sediment core, DD-01, was collected from Cattle Pond, on Dongdao Island in the Xisha Islands. Measurements of grain size, C and N elemental geochemistry, δ13C and biological remains were taken, and a 210Pb chronology established, to study the evolution of the sedimentary environment of Dongdao Island. The results indicate that 4 depositional units can be distinguished between the bottom and the surface layers. The sediment unit below 34 cm was more influenced by guano than the others; its TN and TOC contents are between 0.15%-0.27% and 1.78%-2.8% respectively, δ13C ranges from -24.86‰ to -23.84‰, and there is a large amount of guano sediment, caryopses, and fresh Ostracodes residues. At a depth of 28-34 cm (about 132 a BP), the guano sediment, caryopses and fresh Ostracodes residues disappear, and the number of foraminifers and sea urchin spines increases sharply. The TOC values in this unit are between 1.25% and 2.28%, and TN ranges from 0.11% to 0.29%. δ13C values vary in the range of -25.95‰ to -25.45‰, which is much lower than those in the top 28 cm and those in the bottom 34 cm. A larger mean grain size was also observed, with a stable value of 1.3 Φ, and TIC values were higher at between 10.95% and 11.26%. All of this data shows that this sediment unit may have been influenced by marine dynamic events, which changed the environment of Cattle Pond over a long period. At a depth of 19-28 cm, TN and TOC show increasing trends, and the caryopses reappear. The sediment is more affected by cow-dung and the δ13C remains at a low level. Above 19 cm (about 90 a BP), the TN and TOC values increase rapidly but with fluctuations, suggesting an increasing source of organic matter. An increasing trend in δ13C is related to the input of guano, which was caused by recovery of the sea bird population.
A sediment core, DD-01, was collected from Cattle Pond, on Dongdao Island in the Xisha Islands. Measurements of grain size, C and N elemental geochemistry, δ13C and biological remains were taken, and a 210Pb chronology established, to study the evolution of the sedimentary environment of Dongdao Island. The results indicate that 4 depositional units can be distinguished between the bottom and the surface layers. The sediment unit below 34 cm was more influenced by guano than the others; its TN and TOC contents are between 0.15%-0.27% and 1.78%-2.8% respectively, δ13C ranges from -24.86‰ to -23.84‰, and there is a large amount of guano sediment, caryopses, and fresh Ostracodes residues. At a depth of 28-34 cm (about 132 a BP), the guano sediment, caryopses and fresh Ostracodes residues disappear, and the number of foraminifers and sea urchin spines increases sharply. The TOC values in this unit are between 1.25% and 2.28%, and TN ranges from 0.11% to 0.29%. δ13C values vary in the range of -25.95‰ to -25.45‰, which is much lower than those in the top 28 cm and those in the bottom 34 cm. A larger mean grain size was also observed, with a stable value of 1.3 Φ, and TIC values were higher at between 10.95% and 11.26%. All of this data shows that this sediment unit may have been influenced by marine dynamic events, which changed the environment of Cattle Pond over a long period. At a depth of 19-28 cm, TN and TOC show increasing trends, and the caryopses reappear. The sediment is more affected by cow-dung and the δ13C remains at a low level. Above 19 cm (about 90 a BP), the TN and TOC values increase rapidly but with fluctuations, suggesting an increasing source of organic matter. An increasing trend in δ13C is related to the input of guano, which was caused by recovery of the sea bird population.
2017, 39(6): 55-61.
doi: 10.3969/j.issn.0253-4193.2017.06.006
Abstract:
Neon flying squid (Ommastrephes bartramii) is one of the most important economic cephalopods in the Northwest Pacific Ocean. Building scientific forecast model of abundance index to this squid is beneficial for its exploitation and utilization. In this study, based on the fishing data of this squid in Northwest Pacific Ocena from 1998 to 2008, we analyzed the relationship between the environmental and climatic factors and the catch per unit effort (CPUE) of the winter-spring cohort in its spawning grounds. Therefore, a CPUE forecast model of winter-spring cohort of neon flying squid was built. The grey correlation analysis showed that the most important factors affecting this squid CPUE included average sea surface temperature (SST) in March, Pacific Decadal Oscillatio index (PDO) in January, Niño3.4 index in April and average chlorophyll a concentration (Chl a) in April. Results suggested that the GM (1,4) model which did not include the Niño3.4 anomaly had the best model effects. And its average absolute error was 19.2%. Therefore, we suggested that this model can be used to forecast the CPUE of winter-spring cohort of neon flying squid.
Neon flying squid (Ommastrephes bartramii) is one of the most important economic cephalopods in the Northwest Pacific Ocean. Building scientific forecast model of abundance index to this squid is beneficial for its exploitation and utilization. In this study, based on the fishing data of this squid in Northwest Pacific Ocena from 1998 to 2008, we analyzed the relationship between the environmental and climatic factors and the catch per unit effort (CPUE) of the winter-spring cohort in its spawning grounds. Therefore, a CPUE forecast model of winter-spring cohort of neon flying squid was built. The grey correlation analysis showed that the most important factors affecting this squid CPUE included average sea surface temperature (SST) in March, Pacific Decadal Oscillatio index (PDO) in January, Niño3.4 index in April and average chlorophyll a concentration (Chl a) in April. Results suggested that the GM (1,4) model which did not include the Niño3.4 anomaly had the best model effects. And its average absolute error was 19.2%. Therefore, we suggested that this model can be used to forecast the CPUE of winter-spring cohort of neon flying squid.
2017, 39(6): 62-73.
doi: 10.3969/j.issn.0253-4193.2017.06.007
Abstract:
Variations of Symplectoteuthis oualaniensis resource was studied in Xisha-Zhongsha waters in spring (March to May) during 2006-2010, using standardize catch per unit effort (CPUE) based on Generalized Linear Models (GLM). The relationship between Symplectoteuthis oualaniensis abundance and environmental factors,including satellite remote sensing sea surface wind (SSW), sea surface temperature (SST) and chlorophyll a concentration (Chl a) were analyzed. Results showed that Symplectoteuthis oualaniensis resource increased as while as SST raised in the range of 25-28.5 ℃ and Chl a decreased in the range of 0.1-0.16 mg/m3. The maximum CPUE of Symplectoteuthis oualaniensis appeared when SST varied in the range of 27-28.5℃ and Chl a changed between 0.1-0.13 mg/m3. The peak value of Chl a in Xisha-Zhongsha waters appeared in March, which was one of the breeding months of Symplectoteuthis oualaniensis. The peak value of the Symplectoteuthis oualaniensis resource appeared in May. Response of Symplectoteuthis oualaniensis to Chl a delayed for about two months. In addition, resource abundance of Symplectoteuthis oualaniensis in spring of 2008 fluctuated in wider range, partly connected with climate change induced by La Niña in 2007-2008. Results of this study were meaningful to understand variations of Symplectoteuthis oualaniensis, to guide for scientifically fishing, and to develop fishery resources in deep sea in Xisha-Zhongsha waters, South China Sea.
Variations of Symplectoteuthis oualaniensis resource was studied in Xisha-Zhongsha waters in spring (March to May) during 2006-2010, using standardize catch per unit effort (CPUE) based on Generalized Linear Models (GLM). The relationship between Symplectoteuthis oualaniensis abundance and environmental factors,including satellite remote sensing sea surface wind (SSW), sea surface temperature (SST) and chlorophyll a concentration (Chl a) were analyzed. Results showed that Symplectoteuthis oualaniensis resource increased as while as SST raised in the range of 25-28.5 ℃ and Chl a decreased in the range of 0.1-0.16 mg/m3. The maximum CPUE of Symplectoteuthis oualaniensis appeared when SST varied in the range of 27-28.5℃ and Chl a changed between 0.1-0.13 mg/m3. The peak value of Chl a in Xisha-Zhongsha waters appeared in March, which was one of the breeding months of Symplectoteuthis oualaniensis. The peak value of the Symplectoteuthis oualaniensis resource appeared in May. Response of Symplectoteuthis oualaniensis to Chl a delayed for about two months. In addition, resource abundance of Symplectoteuthis oualaniensis in spring of 2008 fluctuated in wider range, partly connected with climate change induced by La Niña in 2007-2008. Results of this study were meaningful to understand variations of Symplectoteuthis oualaniensis, to guide for scientifically fishing, and to develop fishery resources in deep sea in Xisha-Zhongsha waters, South China Sea.
2017, 39(6): 74-83.
doi: 10.3969/j.issn.0253-4193.2017.06.008
Abstract:
The aim of this study was to investigate the spatio-temporal distribution of Sagitta crassa density and its relationship with environmental factors in the Yellow River estuary and its adjacent waters. The spatial distribution pattern of S. crassa was analyzed by several indices of aggregated intensity based on the data collected in six cruises in 2013 and 2014, and the spatio-temporal distributions of S. crassa density in relation to environmental factors was revealed by generalized additive model (GAM). The results showed that the spatial distribution of S. crassa was in twice aggregation and twice spread, the density of S. crassa was relatively high in the estuary area and low in the offshore waters. The average monthly density of S. crassa was 21.85 ind/m3, and the density in spring and autumn was larger than those in winter and summer. GAM analysis indicated that depth, SST and density of Copepoda were the main affecting factors, which accounted for 55.11% of the residual deviance. The density of S. crassa decreased with the increase of depth, and rose with the increase of Copepoda density, and increased at first then decreased later with the SST increasing in the Yellow River Estuary. The overall results revealed an obvious seasonal variation and regular spatial pattern of S. crassa distribution in the Yellow River Estuary and its adjacent waters, which would contribute a better understanding of the effects of environment on zooplankton, providing useful information for further studies on Chaetognatha.
The aim of this study was to investigate the spatio-temporal distribution of Sagitta crassa density and its relationship with environmental factors in the Yellow River estuary and its adjacent waters. The spatial distribution pattern of S. crassa was analyzed by several indices of aggregated intensity based on the data collected in six cruises in 2013 and 2014, and the spatio-temporal distributions of S. crassa density in relation to environmental factors was revealed by generalized additive model (GAM). The results showed that the spatial distribution of S. crassa was in twice aggregation and twice spread, the density of S. crassa was relatively high in the estuary area and low in the offshore waters. The average monthly density of S. crassa was 21.85 ind/m3, and the density in spring and autumn was larger than those in winter and summer. GAM analysis indicated that depth, SST and density of Copepoda were the main affecting factors, which accounted for 55.11% of the residual deviance. The density of S. crassa decreased with the increase of depth, and rose with the increase of Copepoda density, and increased at first then decreased later with the SST increasing in the Yellow River Estuary. The overall results revealed an obvious seasonal variation and regular spatial pattern of S. crassa distribution in the Yellow River Estuary and its adjacent waters, which would contribute a better understanding of the effects of environment on zooplankton, providing useful information for further studies on Chaetognatha.
2017, 39(6): 84-94.
doi: 10.3969/j.issn.0253-4193.2017.06.009
Abstract:
To clarify whether Phaeodactylum tricornutum had allelopathy effect on Aureococcus anophagefferens, we studied the interaction between P. tricornutum and A. anophagefferens and the impacts of P. tricornutum culture media filtrate on A. anophagefferens growth and on chlorophyll fluorescence under laboratory conditions. The results show that, P. tricornutum has allelopathy effect on A. anophagefferens. In the mono-culture, the proliferation of A. anophagefferens followed the Logistic model, and its initial cell density affected significantly the environmental-carrying capacity (K) of algal populations; and K values decreased gradually with the increase of initial cell densities.In the co-culture, the growth of A. anophagefferens was inhibited significantly (P<0.05) by P. tricornutum of different algal initial cell densities, but the inhibitory effect changed indistinctively with the increase of P. tricornutum proportion. In the filtrate cultivation experiment of A. anophagefferens, we found that: P. tricornutum filtrate at 10 mL or 15 mL could remarkably inhibite the growth of A. anophagefferens (P<0.05) with no effect on its chlorophyll fluorescence; P. tricornutum filtrate at 25 mL and 35 mL could cause PSⅡ irreversible damage (Fv/Fm, ΦPSⅡ, alpha, NPQ values reduced) and death of A. anophagefferens.
To clarify whether Phaeodactylum tricornutum had allelopathy effect on Aureococcus anophagefferens, we studied the interaction between P. tricornutum and A. anophagefferens and the impacts of P. tricornutum culture media filtrate on A. anophagefferens growth and on chlorophyll fluorescence under laboratory conditions. The results show that, P. tricornutum has allelopathy effect on A. anophagefferens. In the mono-culture, the proliferation of A. anophagefferens followed the Logistic model, and its initial cell density affected significantly the environmental-carrying capacity (K) of algal populations; and K values decreased gradually with the increase of initial cell densities.In the co-culture, the growth of A. anophagefferens was inhibited significantly (P<0.05) by P. tricornutum of different algal initial cell densities, but the inhibitory effect changed indistinctively with the increase of P. tricornutum proportion. In the filtrate cultivation experiment of A. anophagefferens, we found that: P. tricornutum filtrate at 10 mL or 15 mL could remarkably inhibite the growth of A. anophagefferens (P<0.05) with no effect on its chlorophyll fluorescence; P. tricornutum filtrate at 25 mL and 35 mL could cause PSⅡ irreversible damage (Fv/Fm, ΦPSⅡ, alpha, NPQ values reduced) and death of A. anophagefferens.
2017, 39(6): 95-113.
doi: 10.3969/j.issn.0253-4193.2017.06.010
Abstract:
Benthic diatom is an important biological community in ecosystems of estuaries and mud flats. The abundance and distribution of the benthic diatom could affect the food supply of marine organism and the survival and migration of sea birds. In this study, the community structure and spatial distribution of benthic diatoms in the surface sediments were investigated at the 14 intertidal zones along the Chinese coastline. 153 diatom species were identified from the samples, and diversity index (Shannon-Weaver index from 1.61 to 4.39) and biomass (from 0.09×103 to 10×103 valves/g DW; DW means dry sediment weight) are significantly different in the spatial distribution. Cluster analysis and ANOSIM (r=0.738, P=0.1%< 0.01) indicated that the 14 sampling sites can classify 4 geological groups, according to their diversity and biomass, and the geological groups are in response to the geographical distribution of phytoplankton in the Bohai, Yellow, East and South China Seas, respectively. The correlation analysis indicated that the sediment types and salinity had significant effects on diatom diversity and biomass. Muddy sediments were better for diatom preservation, and species diversity was higher at sites with sandy mud and low salinity. The contents of organic carbon and the biomasses of benthic diatoms in the surface sediments showed significant positive correlation, and the carbon stable isotope ratio (δ13C) values (from -25‰ to -20‰) indicated that organic matters were a mixture of terrestrial and sea sources at most sites. Lower δ13C values in tidal flats of Jian River, Yellow River, Dagu River and Subei coast indicated the significant contribution of benthic diatoms on the organic carbon.
Benthic diatom is an important biological community in ecosystems of estuaries and mud flats. The abundance and distribution of the benthic diatom could affect the food supply of marine organism and the survival and migration of sea birds. In this study, the community structure and spatial distribution of benthic diatoms in the surface sediments were investigated at the 14 intertidal zones along the Chinese coastline. 153 diatom species were identified from the samples, and diversity index (Shannon-Weaver index from 1.61 to 4.39) and biomass (from 0.09×103 to 10×103 valves/g DW; DW means dry sediment weight) are significantly different in the spatial distribution. Cluster analysis and ANOSIM (r=0.738, P=0.1%< 0.01) indicated that the 14 sampling sites can classify 4 geological groups, according to their diversity and biomass, and the geological groups are in response to the geographical distribution of phytoplankton in the Bohai, Yellow, East and South China Seas, respectively. The correlation analysis indicated that the sediment types and salinity had significant effects on diatom diversity and biomass. Muddy sediments were better for diatom preservation, and species diversity was higher at sites with sandy mud and low salinity. The contents of organic carbon and the biomasses of benthic diatoms in the surface sediments showed significant positive correlation, and the carbon stable isotope ratio (δ13C) values (from -25‰ to -20‰) indicated that organic matters were a mixture of terrestrial and sea sources at most sites. Lower δ13C values in tidal flats of Jian River, Yellow River, Dagu River and Subei coast indicated the significant contribution of benthic diatoms on the organic carbon.
2017, 39(6): 114-128.
doi: 10.3969/j.issn.0253-4193.2017.06.011
Abstract:
Observations were carried out to analyse nutrient dynamics in the lower reaches of Huanghe River from February 2012 to March 2014, including monthly and seasonal variations of nutrient and the effects of water-sediment regulation and rainstorm events freshwater discharge and on nutrient transports. NO3-, DIP and PIP were the major species of TDN, TDP and TPP, respectively. The different forms of N were lower in flood season than in dry season but the DSi and particulate phosphate concentrations were the opposite. The Huanghe River is characterized by high DIN/DIP and DSi/DIP but low DSi/DIN ratios, far from the Redfield ratio. Nutrient transport fluxes show seasonal variations with high values during high freshwater discharge and sediment load season fluxes. From 2002 to 2012, nutrient fluxes during water-sediment regulation and rainstorm periods accounted for 23%—68% and 5%—59% of annual nutrient fluxes, respectively, 38% and 24% of annual nutrient fluxes averages, respectively. Both water-sediment regulation and rainstorm events would result in more water, sediment and nutrients discharged to the coastal water and affect Huanghe River estuary and Bohai Sea ecosystem.
Observations were carried out to analyse nutrient dynamics in the lower reaches of Huanghe River from February 2012 to March 2014, including monthly and seasonal variations of nutrient and the effects of water-sediment regulation and rainstorm events freshwater discharge and on nutrient transports. NO3-, DIP and PIP were the major species of TDN, TDP and TPP, respectively. The different forms of N were lower in flood season than in dry season but the DSi and particulate phosphate concentrations were the opposite. The Huanghe River is characterized by high DIN/DIP and DSi/DIP but low DSi/DIN ratios, far from the Redfield ratio. Nutrient transport fluxes show seasonal variations with high values during high freshwater discharge and sediment load season fluxes. From 2002 to 2012, nutrient fluxes during water-sediment regulation and rainstorm periods accounted for 23%—68% and 5%—59% of annual nutrient fluxes, respectively, 38% and 24% of annual nutrient fluxes averages, respectively. Both water-sediment regulation and rainstorm events would result in more water, sediment and nutrients discharged to the coastal water and affect Huanghe River estuary and Bohai Sea ecosystem.
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