2023 Vol. 42, No. 4
Display Method:
2023, 42(4): 1-15.
doi: 10.1007/s13131-022-2099-9
Abstract:
Taking the advantage of sun glitter (SG) observed from high-resolution satellites Gaofen-1 (GF-1) and Gaofen-6 (GF-6), a new method named Shield and Vortex 1-2 (SAV1-2) for extracting spatial texture information from sun glitter was established. Sea surface texture detail information around Diaoyu Dao and its affiliated islands was extracted using SAV1-2. Meanwhile, the dynamic characteristics of the water environment were analyzed by combining the water color, temperature and dynamic data. The results show the following information. (1) Stable westward shield effect and eastward Karman vortex streets, extracted from SG, appear upstream (westward) and downstream (eastward) of the Diaoyu Dao and its affiliated islands respectively. (2) The dominant direction of the Kuroshio Current in the Diaoyu Dao and its affiliated islands area is east, the Diaoyu Dao and its affiliated islands interacting with Kuroshio, inducing western shield and eastern shelter and wake. Furthermore, wave intervals of the shield in front of the island range from hundreds to thousands of metres, and extend wider than the island itself. (3) Combining with high-resolution sea surface temperature (SST) and chlorophyll a (Chl a) concentration, the directional changes of water color elements are mutually supported and proved with the stable shield (wave packet) effect in the west and vortex street effect in the east. The change of SST upstream of the island (western shield area) is not significant, the temperature in the downstream shelter area decreases slightly, and the SST in the downstream wake area shows a general trend of obvious decrease. The wake area is dominated by Karman vortex streets in shape, supplementing by vortices. The concentration of Chl a in the west shield of island is as low as that in downstream shelter area, while it increases significantly in the downstream wake area with shape in eddy or ribbon. (4) The SAV methods of extracting sea surface texture detail using SG can be widely used in different sea areas and water quality. This paper can provide reference for the protection and development of Diaoyu Dao and its affiliated islands and its surrounding waters. It is suggested that some kind of current buffer, such as marine wind farm, should be established in the western waters of Diaoyu Dao and its affiliated islands to protect the islands, and marine pasture should be developed in the downstream of eastern waters of Diaoyu Dao and its affiliated islands.
Taking the advantage of sun glitter (SG) observed from high-resolution satellites Gaofen-1 (GF-1) and Gaofen-6 (GF-6), a new method named Shield and Vortex 1-2 (SAV1-2) for extracting spatial texture information from sun glitter was established. Sea surface texture detail information around Diaoyu Dao and its affiliated islands was extracted using SAV1-2. Meanwhile, the dynamic characteristics of the water environment were analyzed by combining the water color, temperature and dynamic data. The results show the following information. (1) Stable westward shield effect and eastward Karman vortex streets, extracted from SG, appear upstream (westward) and downstream (eastward) of the Diaoyu Dao and its affiliated islands respectively. (2) The dominant direction of the Kuroshio Current in the Diaoyu Dao and its affiliated islands area is east, the Diaoyu Dao and its affiliated islands interacting with Kuroshio, inducing western shield and eastern shelter and wake. Furthermore, wave intervals of the shield in front of the island range from hundreds to thousands of metres, and extend wider than the island itself. (3) Combining with high-resolution sea surface temperature (SST) and chlorophyll a (Chl a) concentration, the directional changes of water color elements are mutually supported and proved with the stable shield (wave packet) effect in the west and vortex street effect in the east. The change of SST upstream of the island (western shield area) is not significant, the temperature in the downstream shelter area decreases slightly, and the SST in the downstream wake area shows a general trend of obvious decrease. The wake area is dominated by Karman vortex streets in shape, supplementing by vortices. The concentration of Chl a in the west shield of island is as low as that in downstream shelter area, while it increases significantly in the downstream wake area with shape in eddy or ribbon. (4) The SAV methods of extracting sea surface texture detail using SG can be widely used in different sea areas and water quality. This paper can provide reference for the protection and development of Diaoyu Dao and its affiliated islands and its surrounding waters. It is suggested that some kind of current buffer, such as marine wind farm, should be established in the western waters of Diaoyu Dao and its affiliated islands to protect the islands, and marine pasture should be developed in the downstream of eastern waters of Diaoyu Dao and its affiliated islands.
2023, 42(4): 16-24.
doi: 10.1007/s13131-022-2111-4
Abstract:
In this study, the nitrogen and oxygen isotope compositions of nitrite in the upper 150 m water column of the Amundsen Sea in the summer of 2019 and 2020 were measured to reveal the distribution and transformation of nitrite in the euphotic zone of the Southern Ocean. We found that primary nitrite maxima (PNMs) are widely present in the Amundsen Sea, where the depth of occurrence deepens from east to west and nitrite concentrations increases. Evidence from dual isotopes suggests that the formation of PNMs in all regions of the Amundsen Sea is dominated by ammonia oxidation. More importantly, the nitrogen and oxygen isotope compositions of nitrite in the Amundsen Sea mixed layer are abnormal, and their depth profiles are mirror symmetrical. Isotopic anomalies exhibit spatial variations, with central surface water having the lowest nitrogen isotope composition (−89.9‰±0.2‰) and western surface water having the highest oxygen isotope composition (63.3‰±0.3‰). Isotopic exchange reaction between nitrate and nitrite is responsible for these isotope anomalies, as both nitrogen and oxygen isotopes have large isotopic fractionation and opposite enrichment effects. This proves that isotopic exchange reaction operates extensively in different regions of the Amundsen Sea. Our study highlights the unique role of dual isotopes of nitrite in deepening the understanding of nitrogen cycle. Further studies on ammonia oxidation and isotopic exchange between nitrate and nitrite are warranted in the future to understand their roles in the nitrogen cycle in the Southern Ocean.
In this study, the nitrogen and oxygen isotope compositions of nitrite in the upper 150 m water column of the Amundsen Sea in the summer of 2019 and 2020 were measured to reveal the distribution and transformation of nitrite in the euphotic zone of the Southern Ocean. We found that primary nitrite maxima (PNMs) are widely present in the Amundsen Sea, where the depth of occurrence deepens from east to west and nitrite concentrations increases. Evidence from dual isotopes suggests that the formation of PNMs in all regions of the Amundsen Sea is dominated by ammonia oxidation. More importantly, the nitrogen and oxygen isotope compositions of nitrite in the Amundsen Sea mixed layer are abnormal, and their depth profiles are mirror symmetrical. Isotopic anomalies exhibit spatial variations, with central surface water having the lowest nitrogen isotope composition (−89.9‰±0.2‰) and western surface water having the highest oxygen isotope composition (63.3‰±0.3‰). Isotopic exchange reaction between nitrate and nitrite is responsible for these isotope anomalies, as both nitrogen and oxygen isotopes have large isotopic fractionation and opposite enrichment effects. This proves that isotopic exchange reaction operates extensively in different regions of the Amundsen Sea. Our study highlights the unique role of dual isotopes of nitrite in deepening the understanding of nitrogen cycle. Further studies on ammonia oxidation and isotopic exchange between nitrate and nitrite are warranted in the future to understand their roles in the nitrogen cycle in the Southern Ocean.
2023, 42(4): 25-32.
doi: 10.1007/s13131-022-2087-0
Abstract:
Mangrove forests are under the stress of sea level rise (SLR) which would affect mangrove soil biogeochemistry. Mangrove soils are important sources of soil-atmosphere greenhouse gas (GHG) emissions, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Understanding how SLR influences GHG emissions is critical for evaluating mangrove blue carbon capability. In this study, potential effects of SLR on the GHG emissions were quantified through static closed chamber technique among three sites under different intertidal elevations, representing tidal flooding situation of SLR values of 0 cm, 40 cm and 80 cm, respectively. Compared with Site SLR 0 cm, annual CO2 and N2O fluxes decreased by approximately 75.0% and 27.3% due to higher soil water content, lower salinity and soil nutrient environments at Site SLR 80 cm. However, CH4 fluxes increased by approximately 13.7% at Site SLR 40 cm and 8.8% at Site SLR 80 cm because of lower salinity, higher soil water content and soil pH. CO2-equivalent fluxes were 396.61 g/(m2·a), 1423.29 g/(m2·a) and 1420.21 g/(m2·a) at Sites SLR 80 cm, SLR 40 cm and SLR 0 cm, respectively. From Site SLR 0 cm to Site SLR 80 cm, contribution rate of N2O and CH4 increased by approximately 7.42% and 3.02%, while contribution rate of CO2 decreased by approximately 10.44%. The results indicated that warming potential of trace CH4 and N2O was non-negligible with SLR. Potential effects of SLR on the mangrove blue carbon capability should warrant attention due to changes of all three greenhouse gas fluxes with SLR.
Mangrove forests are under the stress of sea level rise (SLR) which would affect mangrove soil biogeochemistry. Mangrove soils are important sources of soil-atmosphere greenhouse gas (GHG) emissions, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Understanding how SLR influences GHG emissions is critical for evaluating mangrove blue carbon capability. In this study, potential effects of SLR on the GHG emissions were quantified through static closed chamber technique among three sites under different intertidal elevations, representing tidal flooding situation of SLR values of 0 cm, 40 cm and 80 cm, respectively. Compared with Site SLR 0 cm, annual CO2 and N2O fluxes decreased by approximately 75.0% and 27.3% due to higher soil water content, lower salinity and soil nutrient environments at Site SLR 80 cm. However, CH4 fluxes increased by approximately 13.7% at Site SLR 40 cm and 8.8% at Site SLR 80 cm because of lower salinity, higher soil water content and soil pH. CO2-equivalent fluxes were 396.61 g/(m2·a), 1423.29 g/(m2·a) and 1420.21 g/(m2·a) at Sites SLR 80 cm, SLR 40 cm and SLR 0 cm, respectively. From Site SLR 0 cm to Site SLR 80 cm, contribution rate of N2O and CH4 increased by approximately 7.42% and 3.02%, while contribution rate of CO2 decreased by approximately 10.44%. The results indicated that warming potential of trace CH4 and N2O was non-negligible with SLR. Potential effects of SLR on the mangrove blue carbon capability should warrant attention due to changes of all three greenhouse gas fluxes with SLR.
2023, 42(4): 33-40.
doi: 10.1007/s13131-022-2088-z
Abstract:
The migration and transformation of nitrogen (N) in sediments play an important role in regulating the N concentration and nutrient structures in shallow seas. However, studies of sedimentary N dynamics are rarely focused on carbonate sediments, although these account for about 40% of the continental shelf area. Thus, the regulation mechanisms of the N dynamics in the carbonate sands of coral reefs are not clear. Taking the coral reef area of Weizhou Island, which has a relatively high N concentration, as the research object, we conducted a series of flow-through reactor experiments to investigate the fluxes of different N forms at the interface of sediment and seawater and their regulation mechanism by environmental factors. The fluxes of dissolved inorganic and organic N (DIN and DON) at different stations were −0.39–0.12 mmol/(m2·h) and −0.18–0.39 mmol/(m2·h), respectively. Denitrification (0.11–0.25 mmol/(m2·h)) was closely coupled to nitrification, which was limited by the availability of organic matter and its degradation product (i.e.,\begin{document}${\rm{NH}}_4^+ $\end{document} ![]()
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The migration and transformation of nitrogen (N) in sediments play an important role in regulating the N concentration and nutrient structures in shallow seas. However, studies of sedimentary N dynamics are rarely focused on carbonate sediments, although these account for about 40% of the continental shelf area. Thus, the regulation mechanisms of the N dynamics in the carbonate sands of coral reefs are not clear. Taking the coral reef area of Weizhou Island, which has a relatively high N concentration, as the research object, we conducted a series of flow-through reactor experiments to investigate the fluxes of different N forms at the interface of sediment and seawater and their regulation mechanism by environmental factors. The fluxes of dissolved inorganic and organic N (DIN and DON) at different stations were −0.39–0.12 mmol/(m2·h) and −0.18–0.39 mmol/(m2·h), respectively. Denitrification (0.11–0.25 mmol/(m2·h)) was closely coupled to nitrification, which was limited by the availability of organic matter and its degradation product (i.e.,
2023, 42(4): 41-49.
doi: 10.1007/s13131-022-2035-z
Abstract:
Total dissolved nitrogen (TDN) is an important parameter for assessing the nutrient cycling and status of natural waters. The accurate determination of TDN in natural waters is essential for assessing its contents and distinguishing different forms of nitrogen in the water. The TDN in various systems has been largely documented, and the concentrations of TDN are usually obtained using high-temperature catalytic (HTC) or persulfate oxidation (PO). However, the accuracy of these methods and their suitability for all types of natural waters are still unclear. To explore both methods in-depth, assorted samples were tested, including eight solutions composed of nitrogen-containing compounds (3 dissolved inorganic nitrogen fractions:\begin{document}${{\rm {NO}}_3^-}$\end{document} ![]()
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\begin{document}${{\rm {NH}}_4^+} $\end{document} ![]()
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Total dissolved nitrogen (TDN) is an important parameter for assessing the nutrient cycling and status of natural waters. The accurate determination of TDN in natural waters is essential for assessing its contents and distinguishing different forms of nitrogen in the water. The TDN in various systems has been largely documented, and the concentrations of TDN are usually obtained using high-temperature catalytic (HTC) or persulfate oxidation (PO). However, the accuracy of these methods and their suitability for all types of natural waters are still unclear. To explore both methods in-depth, assorted samples were tested, including eight solutions composed of nitrogen-containing compounds (3 dissolved inorganic nitrogen fractions:
2023, 42(4): 50-58.
doi: 10.1007/s13131-023-2182-x
Abstract:
The quantification of transparent exopolymer particles (TEP) by colorimetric method is of large error and low repeatability, one major reason of which is related to the absence of clear definition and evaluation for part steps of the original method. It is obscure that the 80% sulfuric acid solution, acted as the extraction solution in the determination of TEP, is prepared based on a volume ratio or mass ratio. Furthermore, the change of solubility of recently available Gum Xanthan (GX) from the market means that the original protocol is no longer applicable, and the grinding of GX stock solution with a tissue grinder is replaced by shaking with a rotating shaker in the study to prevent the excessive dissolution of GX. We found that different preparation techniques could result in the varied concentrations of 80% H2SO4. The duration of shaking during the preparation of standard solution significantly affected the slope of the calibration curve, which caused different correction results of TEP. The impacts of different extraction solution concentrations and shaking time of GX solution on the quantification of TEP were investigated based on the field sampling and laboratory analysis. The extraction capacities of H2SO4 with different concentrations for Alcian Blue were distinct, but had limited effect on the final measuring result of TEP. The change of the standard curve slope came along with the variation of shaking time, which markedly altered the detection limit and calibration result, and the extended shaking time was in favor of the determination of low-concentration TEP. It was suggested that the extraction solution concentration, shaking time and filtration volume of standard solution are required to be well controlled and selected to obtain more accurate results for TEP with different concentrations.
The quantification of transparent exopolymer particles (TEP) by colorimetric method is of large error and low repeatability, one major reason of which is related to the absence of clear definition and evaluation for part steps of the original method. It is obscure that the 80% sulfuric acid solution, acted as the extraction solution in the determination of TEP, is prepared based on a volume ratio or mass ratio. Furthermore, the change of solubility of recently available Gum Xanthan (GX) from the market means that the original protocol is no longer applicable, and the grinding of GX stock solution with a tissue grinder is replaced by shaking with a rotating shaker in the study to prevent the excessive dissolution of GX. We found that different preparation techniques could result in the varied concentrations of 80% H2SO4. The duration of shaking during the preparation of standard solution significantly affected the slope of the calibration curve, which caused different correction results of TEP. The impacts of different extraction solution concentrations and shaking time of GX solution on the quantification of TEP were investigated based on the field sampling and laboratory analysis. The extraction capacities of H2SO4 with different concentrations for Alcian Blue were distinct, but had limited effect on the final measuring result of TEP. The change of the standard curve slope came along with the variation of shaking time, which markedly altered the detection limit and calibration result, and the extended shaking time was in favor of the determination of low-concentration TEP. It was suggested that the extraction solution concentration, shaking time and filtration volume of standard solution are required to be well controlled and selected to obtain more accurate results for TEP with different concentrations.
2023, 42(4): 59-71.
doi: 10.1007/s13131-022-2053-x
Abstract:
Climate change has affected and will continue to affect the spatial distribution patterns of marine organisms. To understand the impact of climate change on the distribution patterns and species richness of the Sciaenidae in China’s coastal waters, the maximum entropy model was used to combine six environmental factors and predict the potential distribution of 12 major species of Sciaenidae by 2050s under Representative Concentration Pathways (RCPs) 2.6 and 8.5. The results showed that the average area under the receiver operating characteristic curve of the model was 0.917, indicating that the model predictions were accurate and reliable. The main driving factors affecting the potential distribution of these fishes were dissolved oxygen, salinity, and sea surface temperature (SST). There was an overall northward shift in the potential habitat areas of these fishes under the two climate scenarios. The total potential habitat areas of Larimichthys polyactis, Pennahia argentata, and Pennahia pawak decreased under both climate scenarios, while the total habitat area of Johnius belengerii, Pennahia anea, Miichthys miiuy, Collichthys lucidus, and Collichthys niveatus increased, suggesting that these might be loser and winner species, respectively. The expansion rate, contraction rate, degree of centroid change, and species richness in the potential habitats were generally more significant under RCP8.5 than RCP2.6. The mean shift rates of the potential distribution were 41.50 km/(10 a) and 29.20 km/(10 a) under RCP8.5 and RCP2.6, respectively. The changes in Sciaenidae species richness under climate change were bounded by the Changjiang River Estuary waters, with obvious north-south differences. Some waters with increased species richness may become refuges for Sciaenidae fishes under climate change. The richness and habitat area change rate of some aquatic germplasm resources will decrease, meanings that these reserves are more sensitive to climate change, and more attention should be paid to the potential challenges and opportunities for fishery managers. This study may provide a scientific basis for the management and conservation of Sciaenidae in China under climate change.
Climate change has affected and will continue to affect the spatial distribution patterns of marine organisms. To understand the impact of climate change on the distribution patterns and species richness of the Sciaenidae in China’s coastal waters, the maximum entropy model was used to combine six environmental factors and predict the potential distribution of 12 major species of Sciaenidae by 2050s under Representative Concentration Pathways (RCPs) 2.6 and 8.5. The results showed that the average area under the receiver operating characteristic curve of the model was 0.917, indicating that the model predictions were accurate and reliable. The main driving factors affecting the potential distribution of these fishes were dissolved oxygen, salinity, and sea surface temperature (SST). There was an overall northward shift in the potential habitat areas of these fishes under the two climate scenarios. The total potential habitat areas of Larimichthys polyactis, Pennahia argentata, and Pennahia pawak decreased under both climate scenarios, while the total habitat area of Johnius belengerii, Pennahia anea, Miichthys miiuy, Collichthys lucidus, and Collichthys niveatus increased, suggesting that these might be loser and winner species, respectively. The expansion rate, contraction rate, degree of centroid change, and species richness in the potential habitats were generally more significant under RCP8.5 than RCP2.6. The mean shift rates of the potential distribution were 41.50 km/(10 a) and 29.20 km/(10 a) under RCP8.5 and RCP2.6, respectively. The changes in Sciaenidae species richness under climate change were bounded by the Changjiang River Estuary waters, with obvious north-south differences. Some waters with increased species richness may become refuges for Sciaenidae fishes under climate change. The richness and habitat area change rate of some aquatic germplasm resources will decrease, meanings that these reserves are more sensitive to climate change, and more attention should be paid to the potential challenges and opportunities for fishery managers. This study may provide a scientific basis for the management and conservation of Sciaenidae in China under climate change.
2023, 42(4): 72-80.
doi: 10.1007/s13131-022-2042-0
Abstract:
Acanthogobius ommaturus, which belongs to the family Gobiidae, is a euryhaline and demersal fish that is widely distributed in the coastal areas, harbors, and estuaries of China, D. P. R. Korea and Japan. In this study, the genetic diversity and genetic structure of five geographical populations of A. ommaturus was assessed using the mitochondrial hypervariable region gene and microsatellite markers. The results of the two genetic markers indicated that the A. ommaturus populations had a high level of genetic diversity. The mitochondrial marker detected weak genetic differentiation among populations, and the Neighbor-Joining tree showed that there was no obvious pedigree branches and geographic structure as well. However, population of Zhoushan showed significant genetic differentiation with other populations by microsatellite markers. The population of A. ommaturus has not experienced bottleneck effect recently. We speculated that the Pleistocene climate change and juvenile fish dispersal played an important role in the population differentiation of A. ommaturus.
Acanthogobius ommaturus, which belongs to the family Gobiidae, is a euryhaline and demersal fish that is widely distributed in the coastal areas, harbors, and estuaries of China, D. P. R. Korea and Japan. In this study, the genetic diversity and genetic structure of five geographical populations of A. ommaturus was assessed using the mitochondrial hypervariable region gene and microsatellite markers. The results of the two genetic markers indicated that the A. ommaturus populations had a high level of genetic diversity. The mitochondrial marker detected weak genetic differentiation among populations, and the Neighbor-Joining tree showed that there was no obvious pedigree branches and geographic structure as well. However, population of Zhoushan showed significant genetic differentiation with other populations by microsatellite markers. The population of A. ommaturus has not experienced bottleneck effect recently. We speculated that the Pleistocene climate change and juvenile fish dispersal played an important role in the population differentiation of A. ommaturus.
2023, 42(4): 81-92.
doi: 10.1007/s13131-022-2054-9
Abstract:
Complete mitochondrial genomes (mitogenomes) can provide useful information for phylogenetic relationships, gene rearrangement, and molecular evolution. In the present study, two newly sequenced mitogenomes of Ocypodoidea (Cleistostoma dilatatum and Euplax sp.) were reported for the first time, which are 15 444 bp and 16 129 bp in length, respectively. Cleistostoma dilatatum is the first species in the family Camptandriidae whose complete mitogenome was sequenced. Each mitogenome contains an entire set of 37 genes and a putative control region, but their gene arrangements are largely different. Tandem duplication and random loss model is proposed to account for their gene arrangements. Comparative genomic analyses of 19 mitogenomes clustering in one branch reveal that 18 of them shared the same gene rearrangement, while that of C. dilatatum mitogenome was consistent with the ancestral gene arrangement of Brachyura. The dN/dS ratio analysis shows that all PCGs are evolving under purifying selection. Phylogenetic analyses show that all Macrophalmidae species cluster together as a group, and then form a sister clade with Camptandriidae. Moreover, the polyphyly of three superfamilies (Ocypodoidea, Eriphioidea, and Grapsoidea) is reconfirmed. These findings help to confirm the phylogenetic position of Camptandriidae, as well as provide new insights into the phylogeny of Brachyura.
Complete mitochondrial genomes (mitogenomes) can provide useful information for phylogenetic relationships, gene rearrangement, and molecular evolution. In the present study, two newly sequenced mitogenomes of Ocypodoidea (Cleistostoma dilatatum and Euplax sp.) were reported for the first time, which are 15 444 bp and 16 129 bp in length, respectively. Cleistostoma dilatatum is the first species in the family Camptandriidae whose complete mitogenome was sequenced. Each mitogenome contains an entire set of 37 genes and a putative control region, but their gene arrangements are largely different. Tandem duplication and random loss model is proposed to account for their gene arrangements. Comparative genomic analyses of 19 mitogenomes clustering in one branch reveal that 18 of them shared the same gene rearrangement, while that of C. dilatatum mitogenome was consistent with the ancestral gene arrangement of Brachyura. The dN/dS ratio analysis shows that all PCGs are evolving under purifying selection. Phylogenetic analyses show that all Macrophalmidae species cluster together as a group, and then form a sister clade with Camptandriidae. Moreover, the polyphyly of three superfamilies (Ocypodoidea, Eriphioidea, and Grapsoidea) is reconfirmed. These findings help to confirm the phylogenetic position of Camptandriidae, as well as provide new insights into the phylogeny of Brachyura.
2023, 42(4): 93-102.
doi: 10.1007/s13131-022-2051-z
Abstract:
Stomatopods are better known as mantis shrimp with considerable ecological importance in wide coastal waters globally. Some stomatopod species are exploited commercially, including Oratosquilla oratoria in the Northwest Pacific. Yet, few studies have published to promote accurate habitat identification of stomatopods, obstructing scientific management and conservation of these valuable organisms. This study provides an ensemble modeling framework for habitat suitability modeling of stomatopods, utilizing the O. oratoria stock in the Bohai Sea as an example. Two modeling techniques (i.e., generalized additive model (GAM) and geographical weighted regression (GWR)) were applied to select environmental predictors (especially the selection between two types of sediment metrics) that better characterize O. oratoria distribution and build separate habitat suitability models (HSM). The performance of the individual HSMs were compared on interpolation accuracy and transferability. Then, they were integrated to check whether the ensemble model outperforms either individual model, according to fishers’ knowledge and scientific survey data. As a result, grain-size metrics of sediment outperformed sediment content metrics in modeling O. oratoria habitat, possibly because grain-size metrics not only reflect the effect of substrates on burrow development, but also link to sediment heat capacity which influences individual thermoregulation. Moreover, the GWR-based HSM outperformed the GAM-based HSM in interpolation accuracy, while the latter one displayed better transferability. On balance, the ensemble HSM appeared to improve the predictive performance overall, as it could avoid dependence on a single model type and successfully identified fisher-recognized and survey-indicated suitable habitats in either sparsely sampled or well investigated areas.
Stomatopods are better known as mantis shrimp with considerable ecological importance in wide coastal waters globally. Some stomatopod species are exploited commercially, including Oratosquilla oratoria in the Northwest Pacific. Yet, few studies have published to promote accurate habitat identification of stomatopods, obstructing scientific management and conservation of these valuable organisms. This study provides an ensemble modeling framework for habitat suitability modeling of stomatopods, utilizing the O. oratoria stock in the Bohai Sea as an example. Two modeling techniques (i.e., generalized additive model (GAM) and geographical weighted regression (GWR)) were applied to select environmental predictors (especially the selection between two types of sediment metrics) that better characterize O. oratoria distribution and build separate habitat suitability models (HSM). The performance of the individual HSMs were compared on interpolation accuracy and transferability. Then, they were integrated to check whether the ensemble model outperforms either individual model, according to fishers’ knowledge and scientific survey data. As a result, grain-size metrics of sediment outperformed sediment content metrics in modeling O. oratoria habitat, possibly because grain-size metrics not only reflect the effect of substrates on burrow development, but also link to sediment heat capacity which influences individual thermoregulation. Moreover, the GWR-based HSM outperformed the GAM-based HSM in interpolation accuracy, while the latter one displayed better transferability. On balance, the ensemble HSM appeared to improve the predictive performance overall, as it could avoid dependence on a single model type and successfully identified fisher-recognized and survey-indicated suitable habitats in either sparsely sampled or well investigated areas.
2023, 42(4): 103-113.
doi: 10.1007/s13131-022-2086-1
Abstract:
Understanding the relative roles of local environmental effects and spatial effects on phytoplankton community is of essential importance to study the biogeography of them at regional scale. However, the determinants that driving the biogeography of phytoplankton communities in the coastal area of northern Zhejiang still remained unclear. We surveyed phytoplankton community compositions in water columns associated with environmental and spatial influences across five subzones that geographically covering this region over four seasons. Diatoms and dinoflagellates were recorded as the main dominant groups and Coscinodiscus oculs-iridis, Coscinodiscus jonesianus, and Skeletonema costatum, were identified as the major abundant species existing in all seasons. Spatially structured environmental conditions, rather than pure spatial or environmental factors, substantially shaped the biogeography of phytoplankton community, with the former mainly comprised of water temperature, dissolved oxygen, phosphate, pH, and salinity, and the latter referring to a non-negligible factor. This study was the first integrated research that combining environmental filtering with spatial factors in structuring phytoplankton communities at a complete tempo-spatial scale. Our results may facilitate to the further study of harmful algal blooms early-warning in this region.
Understanding the relative roles of local environmental effects and spatial effects on phytoplankton community is of essential importance to study the biogeography of them at regional scale. However, the determinants that driving the biogeography of phytoplankton communities in the coastal area of northern Zhejiang still remained unclear. We surveyed phytoplankton community compositions in water columns associated with environmental and spatial influences across five subzones that geographically covering this region over four seasons. Diatoms and dinoflagellates were recorded as the main dominant groups and Coscinodiscus oculs-iridis, Coscinodiscus jonesianus, and Skeletonema costatum, were identified as the major abundant species existing in all seasons. Spatially structured environmental conditions, rather than pure spatial or environmental factors, substantially shaped the biogeography of phytoplankton community, with the former mainly comprised of water temperature, dissolved oxygen, phosphate, pH, and salinity, and the latter referring to a non-negligible factor. This study was the first integrated research that combining environmental filtering with spatial factors in structuring phytoplankton communities at a complete tempo-spatial scale. Our results may facilitate to the further study of harmful algal blooms early-warning in this region.
2023, 42(4): 114-123.
doi: 10.1007/s13131-022-2100-7
Abstract:
Since 2015, green tides have been blooming in offshore waters of Qinhuangdao, with serious impacts on the local ecological environment and tourism. Ulva australis, Bryopsis plumosa, and U. prolifera are the dominant species of Qinhuangdao green tides, following a sequential succession pattern. Ulva prolifera is the dominant species, with the highest biomass and the greatest influence on the local ecological environment. To study the reason of green tide dominant species succession and U. profilera became the dominant species with the largest biomass, we compared and analyzed the growth and nutrient uptake capacity of the three algae. The results showed that temperature significantly affects the growth of the three species. Within the temperature range of the experimental setup, the optimum temperature for the growth of U. australis, B. plumosa andU. profilera is 10℃, 15℃, and 20–25℃, respectively. Combined with the temperature variation trend during green tide bloom development, we believe that temperature is the key environmental factor for the succession of the dominant species. Ulva prolifera has a higher growth rate than U. australisand B. plumosa under the same nitrate, ammonium, and phosphate levels. Significant differences in the maximum absorption rate (Rmax) and Rmax/Ks (the relationship between uptake rate and substrate concentration) values indicated that U. prolifera had an apparent competitive advantage over U. australis and B. plumosa regarding nutrient uptake. Therefore, the strong growth and nutrient uptake capacities of U. prolifera might be the main reason for becoming the dominant species with the largest biomass in Qinhuangdao green tides.
Since 2015, green tides have been blooming in offshore waters of Qinhuangdao, with serious impacts on the local ecological environment and tourism. Ulva australis, Bryopsis plumosa, and U. prolifera are the dominant species of Qinhuangdao green tides, following a sequential succession pattern. Ulva prolifera is the dominant species, with the highest biomass and the greatest influence on the local ecological environment. To study the reason of green tide dominant species succession and U. profilera became the dominant species with the largest biomass, we compared and analyzed the growth and nutrient uptake capacity of the three algae. The results showed that temperature significantly affects the growth of the three species. Within the temperature range of the experimental setup, the optimum temperature for the growth of U. australis, B. plumosa andU. profilera is 10℃, 15℃, and 20–25℃, respectively. Combined with the temperature variation trend during green tide bloom development, we believe that temperature is the key environmental factor for the succession of the dominant species. Ulva prolifera has a higher growth rate than U. australisand B. plumosa under the same nitrate, ammonium, and phosphate levels. Significant differences in the maximum absorption rate (Rmax) and Rmax/Ks (the relationship between uptake rate and substrate concentration) values indicated that U. prolifera had an apparent competitive advantage over U. australis and B. plumosa regarding nutrient uptake. Therefore, the strong growth and nutrient uptake capacities of U. prolifera might be the main reason for becoming the dominant species with the largest biomass in Qinhuangdao green tides.
