Xiangshan Bay Research Articles

Sediment Properties and Benthic Fauna Associated with Stock Enhancement and Farming of Marine Bivalve Populations in Xiangshan Bay, China

This study was designed to examine the impacts of ark shell Scapharca subcrenata enhancement and suspended oyster Crassostrea sikamea farming on sediment properties and fauna communities in the benthic zone of Xiangshan Bay, China. Ark shell enhancement took place over 319 days, after which sediment samples were collected from each of the three treatment sites: the enhancement area, an oyster farm, and a control area. Sediments from the oyster farming area had significantly higher moisture and acid volatile sulfide content, and the highest Cu, Zn, Pb, and Cd concentrations in all three treatment areas. The ark shell enhancement area has the lowest total organic carbon. No significant difference was found between the mean grain size in each of the three areas. Benthic fauna communities in the ark shell enhancement area were similar to those in the control area. Among the 16 faunal taxa identified, Ruditapes philippinarum was the most abundant species, followed by Glycera onomichiensis and Musculus senhousia. Suspension feeders were not found in the sediment beneath the oyster rafts. Cluster analysis showed a distinct separation between the benthic fauna communities in the oyster farming area and the other two treatment areas. Ark shell enhancement was thus shown to have minimal impact on the benthic environment, while the raft-farmed oysters had significant effects on the sediment structure and the benthic fauna after more than ten years of farming. The differences between the impacts of ark shell enhancement and oyster farming could be attributed to the slowing of water flow caused by oyster rafts.

Influence of biodeposition by suspended cultured oyster on the distributions of trace elements in multiple media in a semi-enclosed bay of China

It remains unclear how the suspended non-fed bivalve mariculture will alter the coastal transfer and cleaning process of trace elements, the non-degradable contaminants, which have been reported to accumulate in sediment from bivalve mariculture areas. Herein, we set up a field in situ comparative test in the suspended oyster (Crassostrea plicatula) farming area (OF) and reference area (RA) of Xiangshan Bay to verify our hypothesis that the biodepositon of suspended oysters would consolidate trace elements from the water column and transport them to the sediment. Distribution of trace elements in multiple media of biodeposits (BDs), settling particles (SPs), sediments (SEs), and seawater demonstrate that the accelerated deposition of BDs which enriched trace elements from the water column by oysters filtering suspended particles led to trace elements accumulation in SEs from OF. Additionally, As, Cd, Co, Cr, Cu, Ni, V, and Zn were strongly regulated by this process with significant (p<0.05) higher concentrations in SEs from OF (10.96, 0.20, 13.98, 82.40, 38.47, 38.22, 108.57, and 111.20μg/g, repectively) than those from RA (9.43, 0.13, 11.76, 63.30, 30.34, 29.55, 86.59, and 100.24μg/g, repectively), but the extent was different for Mn, Mo, Pb, and W with concentrations in SEs from OF (737.37, 0.81, 30.98, and 3.96μg/g, repectively) and RA (765.25, 0.69, 31.27, and 3.34μg/g, repectively), especially for Rb and Sr with concentrations in SEs from OF (131.13 and 96.24μg/g, repectively) and RA (142.21 and 161.10μg/g, repectively), due to their geochemical and geophysical properties. Moreover, the harvest of hyper-accumulated oysters as a sink for removing trace elements from water column cannot hide the impact of this process.

Hydrodynamics in the tidal flat in semi-enclosed Xiangshan Bay

Tidal flats provide a foundation for biological diversity and marine economy. Xiangshan Bay is a semi-enclosed bay that shelters large areas of tidal flats, and is known for its aquaculture. In this study, field trips were conducted in late autumn to measure the water level, current, water temperature, tidal flat temperature, and turbidity data of the tidal flat in the bay during Typhoon Lingling. The field data were well calibrated and used to investigate the hydrodynamics, temperature, and turbidity of the tidal flat. The results showed that the spring-neap tidal cycles at the sea surface level were well captured at both stations. The maximum tidal range was 5.5 m and 1.5 m during spring and neap tides, respectively. The tidal flat was occasionally exposed to air occasionally (30 min). The current velocity (&amp;lt;0.2 m/s) and waves (&amp;lt;0.15 m) at the field stations were weak, and the direction of flow was controlled by the geomorphology, even during Typhoon Lingling. Water was more turbid at station S2 (&amp;lt;0.8 kg/m3) than at station S1 (&amp;lt;0.2 kg/m3). The sea water temperature and tidal flat temperature were affected by tidal cycles, with larger variations occurring during spring tides than during neap tides. The maximum value of seawater temperature at S1 station was greater than that at station S2 during spring tides. The intrinsic mode functions (IMFs) of sea water temperature and surface tidal flat temperature were similar, as they are both subject to sea-air-tidal flat interactions. The IMFs of the middle and bottom layers in the tidal flat were less correlated. Temperature fluctuations in seawater and tidal flats were mainly affected by air temperature and tides. Small-scale features (&amp;gt;0.5 Hz) were important for water and tidal flat temperatures, particularly during typhoons. These findings provide field data for future studies on eco-hydrology and coastal engineering in tidal flats.

Comparative metabarcoding analysis of phytoplankton community composition and diversity in aquaculture water and the stomach contents of Tegillarca granosa during months of growth

Filter-feeder bivalves and phytoplankton are interdependent. Their interaction plays important role in estuarine and coastal ecosystem. The correlation between bivalve feeding and phytoplankton is highly species specificity and environment dependent. In the background of miniature and nondiatom trend of phytoplankton in coastal seawaters, how bivalve respond and how the response play roles in the phytoplankton community are poorly known. In the present study, by applying DNA metabarcoding approach based on plastid 23S rDNA, this question was addressed by comparing the phytoplankton composition in the seston and the stomach content of blood clam Tegillarca granosa sampled during the growth period from March to November 2020 in an experimental farm on tidal flat in Xiangshan Bay, East China Sea. The result showed that, a total of seven phyla, 55 genera and 73 species of phytoplankton were identified for all samples. Chlorophyta, Bacillariophyta, and Cyanobacteria were found to be three dominant phyla both in the stomach contents and seston. High diversity of pico-sized phytoplankton, which was easy overlooked by microscopy, was revealed both in seston and stomach contents. This result indicated that the clam was able to feed on the pico-sized algae. At the genus level, the most abundant genera were the pico-sized green alga Ostreococcus (6.12 %–67.88 %) in seston and Picochlorum (4.07 %–35.33 %) in the stomach contents. In addition, microalgae of high nutritional value showed trend of higher proportion in stomach contents than that in seston, especially in July and September when significant growth of T. granosa was observed during this period (the body size increased 155 %). Biodiversity of phytoplankton in the seston was totally higher than that in stomach content, however, the changes among the months showed respective trend. Especially in July when the biodiversity was the lowest in seston, that in the stomach content showed the highest. The results indicated that blood clam farming might influence the phytoplankton composition, including those of pico-sized level, although the particular species in seston were mainly correlating with the dominant environmental factors such as temperature, salinity, pH respectively. These results extend the understanding of roles that bivalve aquaculture may play in the changing of coastal phytoplankton community.

Coastal Wetlands Play an Important Role in the Ecological Security Pattern of the Coastal Zone

The construction of an ecological security pattern can effectively overcome the contradiction between regional human exploitation and ecological protection in the coastal zone. Taking the Xiangshan Bay (XSB) basin as an example, this study identified ecological source areas from three aspects, namely ecosystem services’ importance, ecological sensitivity, and landscape connectivity, and then constructed ecological resistance surfaces, identified ecological corridors, and constructed an ecological security pattern. The results show that the natural reserves in the XSB basin were all located in the identified primary ecological source areas, thus indicating the feasibility and reliability of the “importance–connectivity–sensitivity” ecological source identification mechanism in this study. The ecological corridor in the coastal wetland area accounts for about 40% of the total corridor length, which is the link connecting other ecological sources, revealing the important role of coastal wetlands in the coastal ecosystem. Through the ecological security pattern of the XSB basin and field investigation, we put forward suggestions such as clearing Spartina alterniflora, restoring salt marsh wetland vegetation, and strengthening follow-up monitoring for the restoration of coastal wetlands. This study is expected to provide reference and guidance for the improvement of coastal zone ecological protection and restoration.

Bilateral asymmetry of otoliths from Collichthys lucidus of different sizes in Haizhou Bay and Xiangshan Bay.

In recent years, the frequent occurrence of most human activities has seriously affected the structure and functioning of coastal ecosystems. The asymmetric relationship between the left and right otoliths of fish is often used to test the difference in fluctuating asymmetry (FA) reflected by the square of the coefficient of asymmetric variation (CV2 a ), which can be regarded as an important step in the study of marine environmental pressure and implementation of offshore ecological restoration. In this study, the authors tested the bilateral FA of Collichthys lucidus in the coastal waters of Haizhou Bay, Jiangsu, and Xiangshan Bay, Zhejiang, China, using four sagittal otolith characters (length, width, perimeter and area) as biological characters. The results showed that the value of CV2 a in otolith width (more sensitive to environmental pressure) of C. lucidus in Xiangshan Bay was higher than that in Haizhou Bay, indicating that the environmental pressure on Xiangshan Bay was relatively high. The authors did not find any significant differences in the FA of otoliths between different body sizes of C. lucidus, which may be related to the short-distance migration in different regions and the dietary shifts in the life history of this species. The results have conservation and management implications for this population.

Path analysis of desirable traits and evaluation of reproductive performance of Crassostrea sikamea in different ages

Kumamoto oysters (Crassostrea sikamea) are important marine aquaculture shellfish because of their taste and round shell shape. Due to its small size, selective breeding is required to improve its market size, but there are no reports on traits suitable for direction selection and reproductive productivity of Kumamoto oysters of different ages. In this study, path analysis and one-way ANOVA were used to explore the influential indices of oyster body weight and fecundity. The results showed that shell height was the main factor affecting the body weight of Kumamoto oysters at one-year-old and two-year-old, followed by shell length. Body weight was the main factor influencing fecundity, and shell height showed a significant correlation with fecundity. Therefore, shell height should be considered the first parameter for selection when selecting Kumamoto oysters for body weight as the direct selection target. When one-year-old and two-year-old Kumamoto oysters were selected as parents from Xiangshan Bay, hatching parameters and growth parameters of F1 generation larvae were measured. The fecundity and egg diameters were 1.72 × 106 and 46.60 ± 3.62 μm, respectively, which were significantly greater than one-aged oysters (5.86 × 105, 40.26 ± 3.52 μm). The hatching parameters (fertilized egg size, fertilization rate, and hatching rate) and larval growth performance (D-stage veliger and veliger) were similar and did not differ significantly (P > 0.05), and after metamorphosis, there was also no significant difference in shell height size at 40 days of age (P > 0.05). Therefore, there was no significant effect of age on reproduction, larval development, and the early growth of Kumamoto oysters. These results could provide a basis for parental sources and proper traits for Kumamoto oyster selection, which is beneficial to developing and utilizing this excellent germplasm resource.

Modeling Lagrangian residual velocity in a tide-dominated long-narrow bay: case study of the inner Xiangshan Bay

Many tide-dominated long-narrow bays worldwide face marine pollution because of their semi-enclosed nature. The Lagrangian residual velocity (LRV) characterizes the mass transport in shallow seas. Therefore, studying LRV is helpful for solving marine environmental problems. In this study, the inner Xiangshan Bay along the coast of the East China Sea was used as an example to study 3D LRVs in a tide-dominated long-narrow bay. The LRV pattern and its dynamic mechanism were analyzed. The LRV flowed outward in the deep central area and inward in the shallow areas along the bank, with no apparent variation in the vertical direction. Study results indicated that the main controlling dynamics of the LRV were the balance of the tidal-averaged barotropic gradient force and the tidal body force. Additionally, the LRV showed good correspondence with mass transport and previous study in an ideal tide-dominated long-narrow model bay, which provides a reference for pollution control.

Tide-induced Lagrangian residual velocity and dynamic analysis based on field observations in the inner Xiangshan Bay, China

Tide-induced Lagrangian residual velocity and dynamic analysis based on field observations in the inner Xiangshan Bay, China

Metabarcoding of harmful algal bloom species in sediments from four coastal areas of the southeast China.

In the past three decades, harmful algal blooms (HAB) have become more frequent and widespread in southeast Chinese sea areas. Resting stages are regarded as the “seed bank” of algal blooms, and play an important role in initiating HABs. The distribution of resting stages in sediments especially those of HAB species can make good predictions about the potential risk of future blooms, however with limited reports. In this study, surface sediment samples were collected in the four sea areas along the southeast Chinese coasts, including Dafeng Port (DF) in the southern Yellow Sea, Xiangshan Bay (XS), Funing Bay (FN), and Dongshan Bay (DS) in the East China Sea. Diversity and community structure of eukaryotic microalgae in surface sediments were assessed by metabarcoding V4 region of the 18S rDNA, focusing on the distribution of HAB species. Biogenic elements including total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), biogenic silicon (BSi), and moisture content (MC) were analyzed. A total of 454 eukaryotic algal OTUs were detected, which belonged to 31 classes of 9 phyla. Altogether 149 algal species were detected in this study, and 59 taxa have been reported to form resting stages. Eukaryotic algal community was similar in XS, FN and DS of the East China Sea, which were predominated by dinoflagellates. However, algal community was different in DF of the Yellow Sea, and characterized by the dominance of chrysophytes and low OTU richness. The distribution of most abundant HAB species showed positive correlations with TN, BSi, and TOC, suggesting that eutrophication and consequent increase in diatom productivity may have a significant influence on the distribution of HAB species and facilitate the occurrence of HABs. Furthermore, HAB species occurred more abundantly and widely in FN. Our results suggest high potential risks of HABs in the southeast Chinese coast especially in Funing Bay.

Tide-driven microplastics transport in an elongated semi-closed bay: A case study in Xiangshan Bay, China

Coastal bays are important containers for plastic wastes before they enter the ocean. Based on field samples, this study presents the main characteristics of microplastics and uses a numerical model to study the distribution and movement of microplastics as they are driven by tidal flows in an extended semi-closed bay in Xiangshan Bay, China. The laboratory analyses of microplastic samples from 27 pollutant source samples collected in three batches provided fundamental data on microplastics. Our results show that the local microplastics are prevalent (mean abundance: 890.6 ± 419.4 particles/m3) in the water. A higher quantity of fibre- and fragment-type microplastics was identified and compared to other plastic types. The detected microplastics varied in colour and composition. The simulation suggests that the bay can trap microplastics inside it, with only 16.92 % discharged into the open ocean. A series of single-source numerical tests at nine typical observation sites were conducted to examine tide-driven microplastic transport. Our results suggest that the release location is crucial to microplastic distribution. Specifically, the microplastics tended to accumulate near the bay mouth and the Tie inlet; the microplastics released from the north shore generally evacuated the bay more easily; and the inner harbour tended to accumulate microplastics during spring tide, as opposed to the departure of microplastics at the outer bay, while the effect was reversed during neap tide. We further considered the deposit effect, which significantly reduces the discharging rate to 0.04 % with a settling velocity of 0.05 mm/s. These results may have great importance to decision-making, management, and control of microplastic pollution.

Synchronous Assimilation of Tidal Current-Related Data Obtained Using Coastal Acoustic Tomography and High-Frequency Radar in the Xiangshan Bay, China

To accurately reconstruct large-area three-dimensional current fields in coastal regions, simultaneous observations with ten coastal acoustic tomography (CAT) stations and two high-frequency radar (HFR) stations were performed in the Xiangshan Bay (XSB) on 4–5 December 2020. The section-averaged velocity that was observed by CAT and the radial velocity that was observed by HFR were, for the first time, synchronously assimilated into a three-dimensional barotropic ocean model. Compared with acoustic Doppler current profile data, the velocities of the model assimilating both CAT and HFR data had the highest accuracy according to root mean square differences (RMSDs), ranging from 0.05 to 0.08 m/s for all the vertical layers. For the models individually assimilating CAT and HFR, the values in the vertical layers ranged from 0.07 to 0.12 m/s and 0.08 to 0.13 m/s, respectively. A harmonic analysis of the model grid data showed that the spatial mean amplitudes of the M2, M4, and residual currents were 0.66, 0.14, and 0.09 m/s, respectively. Furthermore, the standing wave characteristics of the M2 current and M4 associated-oscillation in the inner XSB, mouth of the Xiangshan fjord, were better captured by the model assimilating both CAT and HFR. Our study demonstrates the advances in three-dimensional tidal current analysis using a model that assimilates both CAT and HFR data, especially in regions with complex coastal geography.

Larval Ecology of Gobiid Fishes in a Subtropical Embayment: Environmental Preferences and Spatiotemporal Habitat Partitioning

Larval ecology of gobiid fishes in Xiangshan Bay of the east coast of China was examined from ichthyoplanktonic data collected during 10 weekly cruises in spring–early summer of 2015. Particular attention was given to their environmental preferences and spatiotemporal habitat partitioning. A total of 87, 007 gobiid larval individuals, distributed in 9 species, were collected. The thermal and salinity preferences of 6 of the 9 gobiid larvae have been determined using a quotient-rule analysis. This work filled some gaps in larval ecology of these poorly studied gobiids. Temporal succession in gobiid larvae composition was strongly evident. The bay ecosystem was mainly occupied by Asian freshwater goby Acanthogobius ommaturus, branded goby Chaeturichthys stigmatias and tank goby Glossogobius giuris, with preferences for temperature bellow 19°C during April to early May, while striped sand goby Amoya pflaumi and burrowing goby Trypauchen vagina, which preferred water temperature above 22°C, predominated the larval assemblage in early June. With respect to spatial distribution, relatively little variation was detected among species. Most of gobiid larvae exhibited little obvious habitat preference except pinkgray goby Amblychaeturichthys hexanema and A. ommaturus, which distributed preferably in the inner zone and mouth of the bay ecosystem, respectively. Water temperature was the major structuring factor of gobiid larvae assemblage structure in the bay. The gobiid larvae exhibited to be particularly susceptible to the rapid rising temperature shocks. Sharp decline in the total abundance of gobiid larvae was detected with each rapid heating process. In addition, significant shift in larval fish composition occurred following the process. The results suggest that pattern of temperature increase in spring and early summer plays a vital role in recruitment success of the gobiid larvae.

Quantifying the Contribution of Each Driving Force to the Lagrangian Residual Velocity in Xiangshan Bay

A three-dimensional numerical model is used to quantitatively evaluate the contribution of each driving force to the Lagrangian residual velocity (LRV) in Xiangshan Bay under conditions of constant buoyancy gradient in time and multi-frequency tide. Each component of the LRV from various processes is derived by tracking each driving force in a tidal period along the particle trajectory. For a comparison of the results, the driving force in the momentum equations is averaged at the fixed points to obtain six components of the Eulerian residual velocity (ERV). A quantitative evaluation of the contribution of each component to the total ERV and total LRV is performed. The sum of the acceleration component, nonlinear advection component, and barotropic pressure gradient component of ERV determines the structure of the total ERV. The LRV is influenced by different dynamic mechanisms. The barotropic pressure gradient component of LRV determines the outflow pattern of the total longitudinal LRV at the surface of the inner Xiangshan Bay, and the density gradient component of LRV is the main determinant of the structure of the total longitudinal LRV at the bottom of the inner Xiangshan Bay. The eddy viscosity component causes the total longitudinal LRV to flow seaward in the Niubi Channel. The sum of the acceleration component and nonlinear advection component of LRV is the main contributor to the inward total longitudinal LRV in the Fodu Channel. The barotropic pressure gradient component leads to total lateral flow in the outer Xiangshan Bay. The collective effect of the components induced by all of the forces determines the structure of the lateral LRV in the inner Xiangshan Bay.

Assessment of submarine groundwater discharge (SGD) and associated nutrient subsidies to Xiangshan Bay (China), an aquaculture area

Submarine groundwater discharge (SGD) is a predominant component of chemical fluxes in the solute budgets in coastal ecosystems because of its large flux and the corresponding concentrated constituents. A quantitative study regarding the mass balance model of 226Ra and 228Ra was performed to assess SGD and associated nutrient inputs in Xiangshan Bay (XSB), a typical Chinese aquaculture bay. Based on these mass balance models, the SGD rates in the XSB Channel were 8.9–13.2 cm d−1. The SGD rates in the three corresponding embayments were 3.5–3.7 cm d−1 in Embayment I, 5.6–5.8 cm d−1 in Embayment II, and 4.5–5.8 cm d−1 in Embayment III. Significant spatial variabilities in SGD rates were observed in the different XSB districts, reflecting that ocean dynamics and anthropogenic activities play significant roles at different scales. SGD-derived nutrient fluxes in XSB were the dominant sources of nutrient loading, and their magnitudes were approximately 1–2 orders larger than those of riverine input. SGD rates in the XSB Channel were approximately three times higher than those in the three embayments, but the SGD-derived nutrient rates in the XSB Channel were comparable with those in the three embayments, even significantly lower than that for NO3-N in the inner regions of the embayment. These results imply that aquaculture activities and urbanization jointly influence SGD. When combined with the results of other studies, our observations demonstrate the significant comprehensive effects of multiple factors on SGD, a critical but overlooked nutrient source.

Influences of Tidal Flat and Thermal Discharge on Heat Dynamics in Xiangshan Bay

Water temperature in estuaries is sensitive to thermal discharges and expansive tidal flats; as such, this parameter is essential in maintaining estuarine ecosystem. Semi-enclosed water bodies with poor water exchange easily accumulate heat. This is especially true for Xiangshan Bay, which contains two power plants and a large area of tidal flats. This bay was used as an example to study water temperature and heat dynamics, considering the thermal discharge and tidal flats. This study developed and validated a three-dimensional hydro-heat flux numerical model using field data on tidal elevation, currents, water temperature, and tidal flat temperature. The Finite Volume Community Ocean Model combines an accurate thermal discharge model with the air-water-tidal flat heat flux model. The findings showed that thermal discharge provides heat to the bay in summer and winter, and increases the water temperature of the entire bay by 0.7°C in summer, while maintaining water temperature at 0.52°C in winter. The atmosphere and open seas had greater impacts on heat in the bay in winter and summer. The atmosphere and tidal flats provided heat to the bay in summer and absorbed heat from the bay during winter; the opposite was true for the open sea. The effect of tidal flats in summer is less than that in winter, and provides 1.31 × 1013 J of heat to the bay in summer, while taking 8.63 × 1013 J of heat from the bay in winter. This study provides a comprehensive understanding of the effects of tidal flats and thermal discharge on water temperature and heat in macro-tidal bays and estuaries; its results are applicable to similar bays around the world.

Investigation the Effect of the Main Land-Based Pollutants in Xiangshan Bay

Abstract This paper analyses and discusses the monthly and annual changes of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) concentrations from main sewage discharge ports in Xiangshan Bay. Using monitoring data obtained from 2010 to 2019, it systematically examines the monthly variation characteristics of the sewage discharge ports and the interannual changes in the fluxes of major pollutants into the sea. The concentrations of COD, TN, and TP, which were relatively high in November and January-March, generally declined. The annual and monthly changes fluctuated, but the flux into the sea generally decreased. The ecological environment of the nearby sea area is adversely affected, chiefly by land-based pollutants. During the five-year period, COD mainly came from soil erosion and domestic pollution, while TN and TP mainly came from agricultural activities and soil erosion. Hence, it is both necessary and urgent to improve the management of the sewage outfalls from land sources into the sea.

Microplastic pollution in the environment and organisms of Xiangshan Bay, East China Sea: An area of intensive mariculture

Microplastic (MP) pollution in oceans is an emerging environmental problem that poses ecological risks for marine ecosystems. Based on the abundance, distribution, and characteristics of microplastics (MPs) in surface water, sediment, and organisms, MP sources, pollution, trophic transfer, and ecological risk in Xiangshan Bay, an area of intensive mariculture in East China Sea, were assessed in this study. MPs were prevalent in the environment and organisms, with overall abundances at a low–medium level compared with the levels in the coastal areas. In water, MPs were more abundant in the inner bay (0.32 items m–3), which is a more significant source of MPs with intensive mariculture than the central (0.09 items m–3) and outer bays (0.07 items m–3). The narrow and land-enclosed inner bay, with weak hydrodynamics for water exchange, retained MPs, thus increasing their abundance. The ecological risk of MPs in water was at a low–moderate level. The MP abundance in sediment did not vary significantly among the three regions of the bay. The morphological characteristics and polymers of the MPs differed in sediment from those in water, which was related to their diverse environmental redistribution routes. MP abundance ingested by organisms were related to their biological features and foraging habits. Overall, fish ingested more MPs than crustaceans, bivalves, and cephalopods, while zooplankton ingested the minimal MPs. Filter feeders ingested less MPs, with a preference for smaller particles than predators. MPs did not show trophic transfer behavior in organisms. Additionally, MPs ingested by infauna showed similar morphological and chemical characteristics compared to sediment at the point of organism residence, whereas MPs ingested by pelagic species were dissimilar to those in surface water. Our findings provide information for understanding MP pollution, source tracing, trophic transfer, and ecological risk assessment in coastal ecosystems.

Evaluation of Multi-Source High-Resolution Remote Sensing Image Fusion in Aquaculture Areas

Image fusion of satellite sensors can generate a high-resolution multi-spectral image from inputs of a high spatial resolution panchromatic image and a low spatial resolution multi-spectral image for feature extraction and target recognition, such as enclosure seines and floating rafts. However, there is currently no clear and definite method of image fusion for different aquaculture areas distribution extraction from high-resolution satellite images. This study uses three types of high-resolution remote sensing images, GF-1 (Gaofen-1), GF-2 (Gaofen-2), and WV-2 (WorldView-2), covering the raft and enclosure seines aquacultures in the Xiangshan Bay, China, to evaluate panchromatic and multispectral image fusion techniques to determine which is the best. This study applied PCA (principal component analysis), GS (Gram-Schmidt), and NNDiffuse (nearest neighbor diffusion) algorithms to panchromatic and multispectral images fusion of GF-1, GF-2, and WV-2. Two quantitative methods are used to evaluate the fusion effect. The first used seven statistical parameters, including gray mean value, standard deviation, information entropy, average gradient, correlation coefficient, deviation index, and spectral distortion. The second is the CQmax index. Comparing the evaluation results by these seven common statistical indicators with the results of the image fusion evaluation by index CQmax, the results prove that the CQmax index can be applied to the evaluation of image fusion effects in different aquaculture areas. For the floating raft cultured area, the conclusion is consentaneous; NNDiffuse was also optimal for GF-1 and GF-2 data, and PCA was optimal for WV-2 data. For the enclosure seines culture area, the conclusion of quantitative evaluations is not consistent and it shows that there is no definite good method that can be applied to all areas; therefore, careful evaluation and selection of the best applicable image fusion method are required according to the study area and sensor images.

流域空间结构指标与药物污染水平的关系研究

PDF HTML阅读 XML下载 导出引用 引用提醒 流域空间结构指标与药物污染水平的关系研究 DOI: 10.5846/stxb202111123174 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31971489） Quantifying relationships between watershed characteristics and pharmaceutical pollution in aquatic environment Author: Affiliation: Fund Project: the National Natural Science Foundation of China (31971489) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:流域地表特征与土地利用结构同流域水环境质量关系密切。流域空间结构指标能够表征流域空间结构特征和生态功能，主要包括流域特征指标和景观格局指数等。为探讨海湾流域生态系统结构与药物污染特征之间的关系，以浙江象山湾为研究区域，采用固相萃取、超高效液相色谱质谱联用等分析手段，研究流域水环境中药物的污染水平、分析其分布特征与流域特征指标和景观结构的关系。结果表明，象山湾22个流域共有22种药物检出，总检出浓度范围为n.d.-220.2 ng/L，主要包括林可霉素、大环内酯类、喹诺酮类、抗癫痫药物、β受体阻滞剂、抗抑郁药物，其中林可霉素、大环内酯类和抗癫痫药物的检出率高达100%，检出浓度分别为2.36-29.1 ng/L、n.d.-35.8 ng/L和n.d.-37.5 ng/L。流域地貌结构指标与水环境药物污染关系密切，其中平均坡度（MS）与药物总浓度、面积高程曲线斜率（SAEC）与β受体阻滞剂都呈显著负相关关系（P<0.01）；流域景观结构也与水环境药物污染紧密相关，其中景观蔓延度指数（CONTAG）、城镇用地面积加权平均形状因子（IsSHAPE-AM）、林地最大斑块景观面积比（fLPI）与药物总浓度呈显著负相关关系（P<0.05），Shannon均匀度指数（SHEI）与药物总浓度呈显著正相关关系（P<0.05）。通过明确药物与流域空间结构指标的关系，可为应用景观生态措施进行流域管理提供科学依据。 Abstract:Watershed characteristics play a significant role in improving water pollution at watershed scale. Understanding the relationships between watershed characteristics and water quality is of great significance for watershed management. Pharmaceuticals are of increasing concern for their ubiquitous detection and potential threat to aquatic environment. However, little is known about the relationships between watershed characteristics and pharmaceutical pollution in the aquatic environment. To study the relationships between watershed characteristics and pharmaceutical pollution in the aquatic environment, we investigated the occurrence of 29 pharmaceuticals and their quantifying relationships with watershed characteristics in Xiangshan Bay, Eastern China. Pharmaceuticals were extracted by using solid-phase extraction (SPE) and analyzed by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The redundancy analysis and regression modeling were used to explore the correlation between watershed characteristics and pharmaceutical concentrations. The results showed that 22 target pharmaceuticals were detected in the surface water samples, with the detected concentrations ranged from not detected (n.d.) to 220.20 ng/L. Lincomycin (100% of samples), macrolides (100% of samples), antiepileptic drugs (100% of samples), beta-blockers (95% of samples), antidepressant drugs (77% of samples) were the predominant compounds with concentration of 2.36-29.1 ng/L, n.d. -35.8 ng/L, n.d. -37.5 ng/L, n.d.-15.0 ng/L, and n.d.-3.49 ng/L, respectively. Redundancy analysis revealed that the concentrations of pharmaceuticals in the watersheds were positively correlated to topographical features of watersheds. Correlation analysis also showed that the total pharmaceutical concentrations had a significantly negative correlation with mean slope (MS) (P<0.01), and beta-blockers had a significantly negative correlation with slope of area elevation curve (SAEC) (P<0.01). The landscape pattern is also a crucial factor for determining pharmaceutical pollution in the aquatic environment. We have also found that the total pharmaceutical concentrations were negatively correlated with contagion (CONTAG) (P<0.05) and positively correlated with Shannon's evenness index (SHEI) (P<0.05). Furthermore, the area-weighted mean shape index of urban land (IsSHAPE-AM) and the largest patch index of forest (fLPI) had significantly negative correlation with total pharmaceutical concentrations (P<0.05). Overall, the watershed characteristics had significant influences on the pharmaceutical pollution. According to pharmaceutical pollution in the watersheds, the study of the watershed characteristics' correlation to water pollution will help better understanding the influences of the surrounding characteristics on the water quality of surface water at watershed scale. These findings can provide scientific support for improving the water pollution control in surface water at watershed scale from the perspective of sustainable landscape management. 参考文献 相似文献 引证文献