The ecological risk and fate of microplastics in the environmental matrices of marine ranching area in coastal water.

The debate surrounding "source" and "sink" of microplastics (MPs) in coastal water has persisted for decades. While the transportation of MPs is influenced by surface runoff and currents, the precise transport patterns remain inadequately defined. In this study, the typical coastal habitat - marine ranching in Haizhou Bay (Jiangsu Province, China) were selected as a case study to assess the ecological risk of MPs. An enhanced framework was employed to assess the entire community characteristics of MPs in various environmental compartments, including surface water (SW), middle water (MW), bottom water (BW), sea bottom sediment (SS), and intertidal sediment (IS). The results of the assessment showed a low risk in the water column and a high risk in the sediment. PERMANOVA based on size and polymer of MPs revealed significant differences between IS and other compartments (SW, MW, BW, and SS) (P < 0.001). The co-occurrence network analysis for MP size indicated that most sites occupied central positions, while the analysis for MP polymer suggested that sites near the marine ranching area held more central positions, with sites in MW, BW, and SS being somewhat related to IS. Generalized additive model (GAM) demonstrated that MP concentration in the water correlated with Chla and nutrients, whereas MPs in sediment exhibited greater susceptibility to dissolved oxygen (DO) and salinity. We believe that except for the natural sedimentation and re-suspension of MPs in the vertical direction, MPs in bottom water may migrate to the surface water due to upwelling mediated by artificial reefs. Additionally, under the combined influence of surface runoff, currents, and tides, MPs may migrate horizontally, primarily occurring between middle and bottom water and sediments. The study recommends limiting and reducing wastewater and sewage discharge, as well as regulating fishing and aquaculture activities to control the sources and sinks of MPs in coastal water. Moreover, it advocates the implementation and strengthening of marine monitoring activities to gain a better understanding of the factors driving MP pollution in marine ranching area.

Trophic transfer and biomagnification of microplastics through food webs in coastal waters: A new perspective from a mass balance model.

Since the 1950s, plastic pollution and its risk have been recognized as irreversible and nonnegligible problems as global plastic production has increased. In recent years, the transport and trophic transfer of microplastics (MPs) in biotic and abiotic environment have attracted extensive attention from researchers. In this study, based on the Ecotracer module from Ecopath with Ecosim (EwE) model, the marine ranching area of Haizhou Bay, Jiangsu Province, China, was taken as a case study by linking the environmental plastic inflow with MPs in organisms to simulate the variation of MPs in the marine food web for 20 years, as well as its potential trophic transfer and biomagnification. We found that the concentration of MPs in top consumers first increased when the concentration of MPs in the environment increased, while that in primary consumers first decreased when the concentration of MPs in the environment decreased. Moreover, high TL consumers had a stronger ability to accumulate MPs, and pelagic prey fishes was the opposite. From the perspective of the food web, all functional groups showed significant trophic magnification along with the trophic level and no biodilution. Generally, there is a direct relationship between the MPs in marine organisms and environmental inflow. If the pollutants flowing into the environment can be reduced, the MP pollution problem in coastal waters will be effectively alleviated. Our research can further provide a scientific basis for ecological risk assessment and management of MPs and biodiversity protection in marine ecosystems.

Distribution characteristics and ecological risk assessment of microplastics in intertidal sediments near coastal water.

Plastic products are widely distributed worldwide and continue to have a negative impact on the environment and organisms. Intertidal regions, which interface between upland and marine ecosystems, are regions of high ecological importance and serve as repositories for a variety of plastic wastes. However, ecological risk assessments of microplastics (MPs) in these transitional environments are still scarce. In this study, the morphological characteristics and spatial distribution of MPs in the intertidal surface sediments of Haizhou Bay were analyzed, and an ecological risk assessment framework for MPs was developed. Overall, the average abundance of MPs in the sediments was 2.31 ± 1.35 pieces/g dw. The size of the MPs was mainly less than 1 mm, and the main shape, color and polymer type of the MPs were mainly fibrous (58%), blue (30%), and PVC (22%), respectively. Cluster analyses showed that the sites could be well distinguished by size and polymer type but not by MP shape and color. According to the hazard scores, most of the sites in this area belonged to a risk level of IV, while the pollution loading index (PLI) showed that most of the sites belonged to a risk level of II. The ecological toxicity risk from the species-sensitive distribution (SSD) model showed that one-third of the sites had ecological MPs toxicity risks to marine organisms. We believe that normalized and standardized assessment methods should be implemented to monitor and manage the risk of MPs in the intertidal sediments. Particularly, the multiple dimensions, standard abundance of MPs, as well as MPs ingestion in the intertidal organisms, should be fully considered in the next step.

Occurrence and accumulation of microplastics in commercial fish in the coastal waters of the Lvsi fishing ground in China.

In recent years, there has been an exponential increase in the research popularity of microplastics (MPs) in offshore marine environments. However, there is still a gap in the research on the accumulation of MPs in different tissues of aquatic organisms and the trophic transfer of MPs between aquatic organisms. The common occurrence of MPs in the gills and guts of 11 species of commercial fishes was examined in the coastal waters of the Lvsi fishing ground (LSFG). The obtained results showed that >85 % of MPs existed in the gills and guts of these fish, and the abundance was 2.39 ± 1.38 pieces/fish and 2.56 ± 1.42 pieces/fish, respectively. Fibrous and blue are the most common colors and shapes of MPs, and PET is the main polymer type. At the species level, the abundance of MPs in the gills and guts of a few fishes (e.g., Larimichthys polyactis, Setipinna tenuifilis, Collichthys lucidus) decreased with increasing body length and body weight (P < 0.05). At the community level, this situation was not significant (P > 0.05). With increasing trophic level (TL), MPs tended to decrease in the gills (trophic magnification factor, TMF = 0.86) but did not significantly vary in the gut. We believe that MPs are multidimensional pollutants, and their accumulation in tissues/organs of organisms has not been accurately and qualitatively determined. To establish the relationship of MP transport and trophic transfer among water, sediments and organisms, we suggest that more efforts should be made to investigate MPs in aquatic organisms in the coastal waters of LSFG and to increase the examination of MPs in the water column and sediments. This study will help us improve our understanding of MPs pollution, and provide a good reference and basis for the management, monitoring and implementation of pollutants in marine organism of coastal water.

Spatial distribution characteristics of microplastics in the seawater column and sediments of the artificial reef area and adjacent water in Haizhou Bay.

Recently, scholars have been increasing concerned about microplastics (MPs). Unfortunately, information is lacking on the spatial distribution patterns of MPs in coastal seas; therefore, our understanding of the extent of offshore MP contamination remains incomplete. MP distribution in the seawater and surface sediments of an aquaculture area (AA), artificial reef area (AR), and comprehensive effect area (CEA) in Haizhou Bay were investigated in this study. The results showed that the mean abundances of MPs in the surface, middle and bottom seawater were 6.98 ± 3.01 n/m3, 9.12 ± 3.07 n/m3 and 10.20 ± 2.41 n/m3, respectively, and that the abundance in the sediment was 3.09 ± 1.16 n/g. The MP abundance in the bottom seawater was significantly higher than that in the surface seawater (P < 0.05). The correlation among MPs at different depths was not significant, but MPs in most habitats showed a significant correlation. We discovered a significant correlation between the abundance of MPs in the CEA seawater and AR sediments, but not between that in the CEA sediments and AR sediments. MPs can be transported from surface seawater to deeper layers by natural deposition processes. The horizontal transport of MPs due to the coastal gulf current and regular semidiurnal tides lead to the correlations observed in of MP abundance among the AA, CEA, and AR. Migration of MPs from the CEA to the AR was primarily caused by the southern eddies in Haizhou Bay, while migration of MPs from the sediment to the seawater could be due to upwelling in the AR. This was also the main reason there was a lack of a correlation between the sediment from the AR and the seawater from the CEA. This work provides a theoretical and empirical foundation for MP transport and source tracking.

Transfer pattern of microplastics at an individual level: A case study of two typical Sciaenidae fish in coastal waters.

Microplastics (MPs) are recognized as global pollutants. The occurrence and distribution of MP transfer at the species level have been reported, but few studies have focused on the individual level. In this study, two typical migratory demersal species (Collichthys lucidus and Larimichthys polyactis, family Sciaenidae) from the coastal waters of the Lvsi fishing ground were selected to analyze the distribution characteristics of MPs in their gastrointestinal tracts and to explore the potential biomagnification of MPs in different body lengths. The results showed that the main MP color found in both species was blue (>80 %), while the main MP shape was fiber (>90 %), and the main MP polymer type was polyethylene terephthalate (PET) (>70 %). Overall, the abundance of MPs in C. lucidus (3.24 ± 1.57 pieces/fish) was higher than that in L. polyactis (2.24 ± 0.56 pieces/fish). The abundance of MPs in C. lucidus with a body length >90 mm was significantly higher than that with a body length <90 mm, and no significant difference was found in L. polyactis. We believe that the shift in feeding habits during the life history of the two species is an important factor that affects the variation in MPs between body lengths. Additionally, there was a significant positive correlation between MPs and the length (weight) of C. lucidus but no correlation in L. polyactis. There was no significant correlation between trophic level and MPs in either species. This indicated that MP bioaccumulation only occurred in C. lucidus, and MP biomagnification did not occur in either species. We suggest that further research be conducted on MPs ingested by more species at an individual level regarding the biomagnification/bioaccumulation phenomenon. This will help further elucidate the characteristics of MP transfer in the food webs of ecosystems and provide theoretical support for understanding MP pollution in coastal waters.

Bilateral fluctuation asymmetry of otoliths of Collichthys lucidus in different functional areas of Haizhou Bay.

The fluctuating asymmetry (FA) of fish otoliths can reflect the difference in the growth and development of fish in sea areas greatly affected by environmental pressure, thus enabling the assessment of different habitats. In this study, using 113 Collichthys lucidus samples collected from different functional areas (estuary area, aquaculture area, artificial reef area and natural area) in Haizhou Bay, the square coefficient of asymmetry variation (CV2 a ) of four characters (length, width, perimeter and area) of the left and right sagittal otoliths was calculated. The results showed that the CV2 a value of otolith width was the lowest and that of otolith length was the highest. The CV2 a value had no obvious regularity with increasing fish body length. In addition, the CV2 a values of the four characteristics reached their lowest values in the artificial reef area, indicating that the construction of marine ranching dominated by artificial reefs may partly improve the aquatic environment in this functional area. We consider that the otolith FA of C. lucidus can be used as a characteristic of environmental stress between different areas/regions/habitats.

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.

The different ways microplastics from the water column and sediment accumulate in fish in Haizhou Bay.

Global microplastic (MP) pollution is a serious environmental problem that has been found in various ecosystems, especially marine ecosystems. In this study, the water (surface, middle and bottom water), sediment and fish (pelagic, demersal and benthic fish) in the artificial reef area and adjacent waters in Haizhou Bay were collected, and the mechanism of MP transmission among the three media was analyzed. The results showed that >96 % of the plastics in the region were MPs. The shape of MPs was mainly fibrous (water (73.3 %), sediment (56 %), fish (95.3 %)), color was mainly blue (water (49.3 %), sediment (47 %), fish (72.3 %)), and the material was mainly PET (water (39.6 %), sediment (33 %), fish (86.6 %)). We found that, except for the natural deposition of MPs, MPs could be ingested by pelagic fish and transmitted through vertical movement in the water, while there was an interaction between MPs in benthic fishes and the middle-bottom waters. In addition, as relevant variables, body length and body weight were more likely to explain the number of MPs ingested by fishes than were δ13C and δ15N. Therefore, based on the linear relationship between δ15N and body length, we concluded that there was a weak trophic magnification effect of MPs ingested by fish in this region. This study provides unique information for further exploring the factors influencing the spatial distribution of MPs and the transmission mechanism of MPs in fish.

The patterns of trophic transfer of microplastic ingestion by fish in the artificial reef area and adjacent waters of Haizhou Bay.

Plastic pollution has become a threat to the global marine environment. Many studies have shown that marine organisms are at risk of plastic ingestion, but there is still a lack of relevant research in the artificial reef area and adjacent waters of Haizhou Bay, located in the western Yellow Sea. The study of MPs will provide useful information for MPs pollution in the artificial reef food webs, as well as the understanding of MPs trophic transfer by reef fish. In this study, we quantified plastic ingestion by marine fish in artificial reef areas and adjacent waters (Natural area, NA; Aquaculture area, AA; Estuary area, EA; Artificial reefs area, AR and Comprehensive effective area, CEA) and analysed the related possible influencing factors. Of the 146 fish samples examined, 100% of fish ingested plastics, and 98.9% of these particles were microplastics (MPs) (<5 mm), with 3.00 ± 2.63 pieces/fish. The main types and colours of MPs were fibre (95.9%) and blue (84%). The MP quantity of AR and AA were significantly higher than that of CEA (P < 0.05) and there is no significant difference among other habitats. The MP ingestion by pelagic fishes was significantly lower than that of demersal fishes (P < 0.05). MP ingestion by omnivores was significantly higher than that by carnivores and planktivores (P < 0.05). The body length (body weight) of four species (Larimichthys polyactis: 17.7-16.7 cm (16.01-59.41 g); Collichthys lucidus: 8.1-14.3 cm (19.65-56.92 g); Tridentiger barbatus: 5.9-9.2 cm (3.37-19.1 g); Cynoglossus joyneri: 10.1-18.7 cm (5-45 g)) had no significant correlation with MP ingestion (P > 0.05). Our results showed that MPs in this region are ubiquitous (i.e., the MP ingestion rate was as high as 100%). We infer that there is a transfer mechanism in MPs from pelagic to benthic fish in this area, and there is weak biomagnification with the trophic transfer of the food chain (TMF = 1.62). However, more practical studies still need to verify whether MPs are actually transferred to humans through trophic transfer from the marine food web.

Microplastics in different tissues of caught fish in the artificial reef area and adjacent waters of Haizhou Bay.

In recent years, the microplastics (MPs) pollution in the offshore of microplastics has gradually become a concerning topic, and the understanding the accumulation of MPs in different tissues of organisms is also an important aspect. MPs can easily affect target tissues and transport related chemicals to humans through the food chain. MPs in the gills and guts of fish in the artificial reef area of Haizhou Bay and adjacent waters were detected in this study. The results showed that MPs were ubiquitous in the gills and guts of 26 species, with average quantities of 3.54 ± 2.14 pieces/fish and 3.00 ± 2.63 pieces/fish, respectively. More than 99% of the plastics were MPs that were less than 5 mm in diameter, with blue fiber being the most common. The number and quantity of MPs in gills were higher than those in guts in different habitat types, living water layers and feeding habits of fish. At the community level, as the body length and body weight increased, the quantity of MPs in the gills and guts showed a slight decreasing trend, and the correlation was not strong (P > 0.05). With increasing trophic levels (TLs), MPs were biomagnified in the guts (Trophic magnification factor, TMF = 1.37), but no change occurred in the gills (TMF = 1.00). We believe that biomagnification of MPs should be obtained by comparing the quantity of MPs in whole organisms rather than only in specific tissues before such conclusions can be defined. We recommend that periodic marine monitoring programs be implemented, as well as research into smaller MPs and even nanoplastics, to assess from the perspective of water, sediments, organisms and ecotoxicology, which will provide useful information for MPs pollution in artificial reefs and help to improve the MPs pollution database in China.

The seasonal variation in heavy metal accumulation in the food web in the coastal waters of Jiangsu based on carbon and nitrogen isotope technology.

Research on food web structures in marine ecosystems is an important field in ecology where the interaction of structure and function contributes to understanding biodiversity. The coastal waters of Jiangsu are one of the important fishing bases in China. In recent years, with the development of industry in the coastal waters of Jiangsu, heavy metal (HM) pollution in this region has become more serious. In this study, all samples (including macroalgae, bivalves, cephalopods, gastropods, crustaceans and fish) were collected in the coastal waters of Jiangsu in spring, summer and autumn. Based on the construction of the food web structure using carbon and nitrogen isotope technology, the main methods of material circulation and energy flow were quantified, and the accumulation regularity and seasonal variation characteristics of HMs in the food web were analysed. The results showed that (1) among all the trophic groups, bivalves had the highest enrichment level of HMs, while fish had the lowest. However, fish have a strong ability to enrich Hg, and the main source of Hg enrichment in the human body is edible fish, so more attention should be given to Hg concentrations in fish. (2) In spring, the mean HM concentrations of marine organisms in the coastal waters of Jiangsu were Zn > Cu > As > Cd > Cr > Pb > Ni > Hg, and they were Zn > Cu > As > Pb > Cd > Ni > Cr > Hg in summer and Zn > Cu > As > Pb > Cd > Cr > Ni > Hg in autumn. In total, the concentrations of Zn, Cu and As were the highest, while the mean concentration of Hg in organisms was the lowest. (3) No significant biomagnification of HMs was found in the three seasons. We speculated that overfishing leads to miniaturization and a younger age of organisms, which makes the concentration of highly enriched HMs in organisms with high trophic levels (TLs) lower.

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We measured the ratio of δ13C and δ15N values to estimate the trophic level of main organisms based on a fisheries resource survey in coastal water of Lyusi fishing ground carried out in September 2018. The results showed that δ13C values of the main organisms ranged from -24.27‰ to -13.24‰, with an average of (-17.15±1.85)‰. The δ15N values ranged from 4.30‰ to 14.61‰, with an average of (11.21±1.90)‰. Results from cluster analysis demonstrated that the main organisms in the coastal water of Lyusi fishery ground could be divided into four trophic groups. The first group was consisted mainly by middle and small fishes, shrimps and other invertebrates. The second group included the small-sized fishes like Konosirus punctatus, Mugil cephalus, etc. and shrimps like Exopalaemon annandalei, Exopalamon carincauda, etc. The phytoplankton belonged to the third group. The fourth group was zooplankton. In the trophic spectrum, the trophic levels of fish, shrimps and crabs, shellfish were 3.2-4.7, 3.2-4.2 and 2.0-4.1, respectively. Most species belonged to the category of middle and high-level consumers. In this survey, the average trophic level of the same species in the coastal waters of Lyusi fishing ground was 0.6, which was higher than that in the East China Sea and Yellow Sea. There was niche overlap of most fish, shrimps and crabs. Those results indicated the growth environment and nutrient structure of most living organisms in this area were generally similar.